From Wikipedia, the free encyclopedia
Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 100 years ending in 2005. The Intergovernmental Panel on Climate Change (IPCC) concludes that most of the temperature increase since the mid-twentieth century is "very likely" due to the increase in anthropogenic greenhouse gas concentrations. Natural phenomena such as solar variation and volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries. While a small minority have voiced disagreement with these findings, the overwhelming majority of scientists working on climate change agree with the IPCC's main conclusions. However, there is significant evidence that the climate models currently in use are unduly optimistic, as they fail generally to include non-linear effects such as the clathrate gun, which may lead to runaway climate change.
Climate model projections indicate that global surface temperature will likely rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century. The uncertainty in this estimate arises from use of differing estimates of future greenhouse gas emissions and from use of models with differing climate sensitivity. Another uncertainty is how warming and related changes will vary from region to region around the globe. Although most studies focus on the period up to 2100, warming is expected to continue for more than a thousand years even if greenhouse gas levels are stabilized unless geoengineering is used. This results from the large heat capacity of the oceans.
Increasing global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, likely including an expanse of the subtropical desert regions. Other likely effects include Arctic shrinkage and resulting Arctic methane release, increases in the intensity of extreme weather events, changes in agricultural yields, modifications of trade routes, glacier retreat, species extinctions and increases in the ranges of disease vectors.
Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions. Political and public debate continues regarding what, if any, action should be taken to reduce or reverse future warming or to adapt to its expected consequences.
Responses to global warming fall into three categories:
- Geoengineering – directly intervening in the climate using techniques such as solar radiation management
- Adaptation – dealing with the effects of global warming, such as by building flood defences
- Mitigation – reducing carbon emissions, such as by using renewable energy and energy efficiency measures.
The causes of the recent warming are an active field of research. The scientific consensus is that the increase in atmospheric greenhouse gases due to human activity has caused most of the warming observed since the start of the industrial era, and the observed warming cannot be satisfactorily explained by natural causes alone. This attribution is clearest for the most recent 50 years, which is the period when most of the increase in greenhouse gas concentrations took place and for which the most complete measurements exist.
The greenhouse effect was discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warm a planet's lower atmosphere and surface. Existence of the greenhouse effect as such is not disputed. The question is instead how the strength of the greenhouse effect changes when human activity increases the atmospheric concentrations of particular greenhouse gases.
Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F), without which Earth would be uninhabitable. On Earth the major greenhouse gases are water vapor, which causes about 36–70 percent of the greenhouse effect (not including clouds); carbon dioxide (CO2), which causes 9–26 percent; methane (CH4), which causes 4–9 percent; and ozone, which causes 3–7 percent.
Human activity since the industrial revolution has increased the atmospheric concentration of various greenhouse gases, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. The atmospheric concentrations of CO2 and methane have increased by 36% and 148% respectively since the beginning of the industrial revolution in the mid-1700s. These levels are considerably higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores. From less direct geological evidence it is believed that CO2 values this high were last seen approximately 20 million years ago. Fossil fuel burning has produced approximately three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, in particular deforestation.
CO2 concentrations are expected to continue to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological, and natural developments. The IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100. Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100 if coal, tar sands or methane clathrates are extensively exploited.
Some other hypotheses departing from the consensus view have been suggested to explain most of the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity.
A paper by Peter Stott and colleagues suggests that climate models overestimate the relative effect of greenhouse gases compared to solar forcing; they also suggest that the cooling effects of volcanic dust and sulfate aerosols have been underestimated. They nevertheless conclude that even with an enhanced climate sensitivity to solar forcing, most of the warming since the mid-20th century is likely attributable to the increases in greenhouse gases. Another paper suggests that the Sun may have contributed about 45–50 percent of the increase in the average global surface temperature over the period 1900–2000, and about 25–35 percent between 1980 and 2000.
A different hypothesis is that variations in solar output, possibly amplified by cloud seeding via galactic cosmic rays, may have contributed to recent warming. It suggests magnetic activity of the sun is a crucial factor which deflects cosmic rays that may influence the generation of cloud condensation nuclei and thereby affect the climate.
One predicted effect of an increase in solar activity would be a warming of most of the stratosphere, whereas an increase in greenhouse gases should produce cooling there. The observed trend since at least 1960 has been a cooling of the lower stratosphere. Reduction of stratospheric ozone also has a cooling influence, but substantial ozone depletion did not occur until the late 1970s. Solar variation combined with changes in volcanic activity probably did have a warming effect from pre-industrial times to 1950, but a cooling effect since. In 2006, Peter Foukal and colleagues found no net increase of solar brightness over the last 1,000 years. Solar cycles led to a small increase of 0.07 percent in brightness over the last 30 years. This effect is too small to contribute significantly to global warming. One paper by Mike Lockwood and Claus Fröhlich found no relation between global warming and solar radiation since 1985, whether through variations in solar output or variations in cosmic rays. Henrik Svensmark and Eigil Friis-Christensen, the main proponents of cloud seeding by galactic cosmic rays, disputed this criticism of their hypothesis. A 2007 paper found that in the last 20 years there has been no significant link between changes in cosmic rays coming to Earth and cloudiness and temperature.
Forcing and feedback
None of the effects of forcing are instantaneous. The thermal inertia of the Earth's oceans and slow responses of other indirect effects mean that the Earth's current climate is not in equilibrium with the forcing imposed. Climate commitment studies indicate that even if greenhouse gases were stabilized at 2000 levels, a further warming of about 0.5 °C (0.9 °F) would still occur.
The Earth's climate changes in response to external forcing, including greenhouse gases, variations in its orbit around the Sun (orbital forcing), changes in solar luminosity, and volcanic eruptions; all examples of the Earth's own variation in temperatures, for which the UNFCCC uses the term climate variability.
When a warming trend results in effects that induce further warming, the process is referred to as a positive feedback; when the effects induce cooling, the process is referred to as a negative feedback. The primary positive feedback involves water vapor. The primary negative feedback is the effect of temperature on emission of infrared radiation: as the temperature of a body increases, the emitted radiation increases with the fourth power of its absolute temperature. This provides a powerful negative feedback which stabilizes the climate system over time.
One of the most pronounced positive feedback effects relates to the evaporation of water. If the atmosphere is warmed, the saturation vapour pressure increases, and the quantity of water vapor in the atmosphere will tend to increase. Since water vapor is a greenhouse gas, the increase in water vapor content makes the atmosphere warm further; this warming causes the atmosphere to hold still more water vapor (a positive feedback), and so on until other processes stop the feedback loop. The result is a much larger greenhouse effect than that due to CO2 alone. Although this feedback process causes an increase in the absolute moisture content of the air, the relative humidity stays nearly constant or even decreases slightly because the air is warmer. This feedback effect can only be reversed slowly as CO2 has a long average atmospheric lifetime.
Feedback effects due to clouds are an area of ongoing research. Seen from below, clouds emit infrared radiation back to the surface, and so exert a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, and so exert a cooling effect. Whether the net effect is warming or cooling depends on details such as the type and altitude of the cloud. These details are difficult to represent in climate models, in part because clouds are much smaller than the spacing between points on the computational grids of climate models.
A subtler feedback process relates to changes in the lapse rate as the atmosphere warms. The atmosphere's temperature decreases with height in the troposphere. Since emission of infrared radiation varies with the fourth power of temperature, longwave radiation emitted from the upper atmosphere is less than that emitted from the lower atmosphere. Most of the radiation emitted from the upper atmosphere escapes to space, while most of the radiation emitted from the lower atmosphere is re-absorbed by the surface or the atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere's rate of temperature decrease with height: if the rate of temperature decrease is greater the greenhouse effect will be stronger, and if the rate of temperature decrease is smaller then the greenhouse effect will be weaker. Both theory and climate models indicate that with increased greenhouse gas content the rate of temperature decrease with height will be reduced, producing a negative lapse rate feedback that weakens the greenhouse effect. Measurements of the rate of temperature change with height are very sensitive to small errors in observations, making it difficult to establish whether the models agree with observations.
Another important feedback process is ice-albedo feedback. When global temperatures increase, ice near the poles melts at an increasing rate. As the ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice, and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continues.
Warming is also the triggering variable for the release of methane from sources both on land and on the deep ocean floor, making both of these possible feedback effects. Thawing permafrost, such as the frozen peat bogs in Siberia, creates a positive feedback due to release of CO2 and CH4. Methane discharge from permafrost is presently under intensive study. Warmer deep ocean temperatures, likewise, could release the greenhouse gas methane from the 'frozen' state of the vast deep ocean deposits of methane clathrate/methane hydrate, according to the Clathrate Gun Hypothesis,
Ocean ecosystems' ability to sequester carbon are expected to decline as it warms. This is because the resulting low nutrient levels of the mesopelagic zone (about 200 to 1000 m depth) limits the growth of diatoms in favor of smaller phytoplankton that are poorer biological pumps of carbon.
Global temperatures have increased by 0.75 °C (1.35 °F) relative to the period 1860–1900, according to the instrumental temperature record. This measured temperature increase is not significantly affected by the urban heat island effect. Since 1979, land temperatures have increased about twice as fast as ocean temperatures (0.25 °C per decade against 0.13 °C per decade). Temperatures in the lower troposphere have increased between 0.12 and 0.22 °C (0.22 and 0.4 °F) per decade since 1979, according to satellite temperature measurements. Temperature is believed to have been relatively stable over the one or two thousand years before 1850, with possibly regional fluctuations such as the Medieval Warm Period or the Little Ice Age.
Sea temperatures increase more slowly than those on land both because of the larger effective heat capacity of the oceans and because the ocean can lose heat by evaporation more readily than the land. The Northern Hemisphere has more land than the Southern Hemisphere, so it warms faster. The Northern Hemisphere also has extensive areas of seasonal snow and sea-ice cover subject to the ice-albedo feedback. More greenhouse gases are emitted in the Northern than Southern Hemisphere, but this does not contribute to the difference in warming because the major greenhouse gases persist long enough to mix between hemispheres.
Based on estimates by NASA's Goddard Institute for Space Studies, 2005 was the warmest year since reliable, widespread instrumental measurements became available in the late 1800s, exceeding the previous record set in 1998 by a few hundredths of a degree. Estimates prepared by the World Meteorological Organization and the Climatic Research Unit concluded that 2005 was the second warmest year, behind 1998. Temperatures in 1998 were unusually warm because the strongest El Niño-Southern Oscillation in the past century occurred during that year.
Anthropogenic emissions of other pollutants—notably sulfate aerosols—can exert a cooling effect by increasing the reflection of incoming sunlight. This partially accounts for the cooling seen in the temperature record in the middle of the twentieth century, though the cooling may also be due in part to natural variability. James Hansen and colleagues have proposed that the effects of the products of fossil fuel combustion—CO2 and aerosols—have, for the short term, largely offset one another, so that net warming in recent decades has been driven mainly by non-CO2 greenhouse gases.
Paleoclimatologist William Ruddiman has argued that human influence on the global climate began around 8,000 years ago with the start of forest clearing to provide land for agriculture and 5,000 years ago with the start of Asian rice irrigation. Ruddiman's interpretation of the historical record, with respect to the methane data, has been disputed.
Pre-human climate variations
Earth has experienced warming and cooling many times in the past. The recent Antarctic EPICA ice core spans 800,000 years, including eight glacial cycles timed by orbital variations with interglacial warm periods comparable to present temperatures.
A rapid buildup of greenhouse gases amplified warming in the early Jurassic period (about 180 million years ago), with average temperatures rising by 5 °C (9 °F). Research by the Open University indicates that the warming caused the rate of rock weathering to increase by 400%. As such weathering locks away carbon in calcite and dolomite, CO2 levels dropped back to normal over roughly the next 150,000 years.
Sudden releases of methane from clathrate compounds (the clathrate gun hypothesis) have been hypothesized as both a cause for and an effect of other warming events in the distant past, including the Permian–Triassic extinction event (about 251 million years ago) and the Paleocene–Eocene Thermal Maximum (about 55 million years ago).
Scientists have studied global warming with computer models of the climate. These models are based on physical principles of fluid dynamics, radiative transfer, and other processes, with simplifications being necessary because of limitations in computer power and the complexity of the climate system. All modern climate models include an atmospheric model that is coupled to an ocean model and models for ice cover on land and sea. Some models also include treatments of chemical and biological processes. These models project a warmer climate due to increasing levels of greenhouse gases. However, even when the same assumptions of future greenhouse gas levels are used, there still remains a considerable range of climate sensitivity.
Including uncertainties in future greenhouse gas concentrations and climate modeling, the IPCC anticipates a warming of 1.1 °C to 6.4 °C (2.0 °F to 11.5 °F) by the end of the 21st century, relative to 1980–1999. Models have also been used to help investigate the causes of recent climate change by comparing the observed changes to those that the models project from various natural and human-derived causes.
Current climate models produce a good match to observations of global temperature changes over the last century, but do not simulate all aspects of climate. These models do not unambiguously attribute the warming that occurred from approximately 1910 to 1945 to either natural variation or human effects; however, they suggest that the warming since 1975 is dominated by man-made greenhouse gas emissions.
Global climate model projections of future climate are forced by imposed greenhouse gas emission scenarios, most often from the IPCC Special Report on Emissions Scenarios (SRES). Less commonly, models may also include a simulation of the carbon cycle; this generally shows a positive feedback, though this response is uncertain. Some observational studies also show a positive feedback. A recent paper has suggested that "global surface temperature may not increase over the next decade, as natural climate variations in the North Atlantic and tropical Pacific temporarily offset the projected anthropogenic warming", based on the inclusion of ocean temperature observations.
The representation of clouds is one of the main sources of uncertainty in present-generation models, though progress is being made on this problem.
A minor issue in climate modeling is the perceived mismatch between actual conditions and those projected by the models. A 2007 study by David Douglass and colleagues compared the composite output of 22 leading global climate models with actual climate data and found that the models did not accurately project observed changes to the temperature profile in the tropical troposphere. The authors note that their conclusions contrast strongly with those of recent publications based on essentially the same data. A 2008 paper published by a 17-member team led by Ben Santer of Lawrence Livermore National Laboratory noted serious mathematical errors and incorrect assumptions in the Douglass study, and found instead that deviations between the models and observations were statistically insignificant.
Attributed and expected effects
Although it is difficult to connect specific weather events to global warming, an increase in global temperatures may in turn cause broader changes, including glacial retreat, Arctic shrinkage, and worldwide sea level rise. Changes in the amount and pattern of precipitation may result in flooding and drought. There may also be changes in the frequency and intensity of extreme weather events. Other effects may include changes in agricultural yields, addition of new trade routes, reduced summer streamflows, species extinctions, and increases in the range of disease vectors.
Some effects on both the natural environment and human life are, at least in part, already being attributed to global warming. A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption such as that of the Larsen Ice Shelf, sea level rise, changes in rainfall patterns, and increased intensity and frequency of extreme weather events are attributable in part to global warming. Other expected effects include water scarcity in some regions and increased precipitation in others, changes in mountain snowpack, and adverse health effects from warmer temperatures.
Social and economic effects of global warming may be exacerbated by growing population densities in affected areas. Temperate regions are projected to experience some benefits, such as fewer deaths due to cold exposure. A summary of probable effects and recent understanding can be found in the report made for the IPCC Third Assessment Report by Working Group II. The newer IPCC Fourth Assessment Report summary reports that there is observational evidence for an increase in intense tropical cyclone activity in the North Atlantic Ocean since about 1970, in correlation with the increase in sea surface temperature (see Atlantic Multidecadal Oscillation), but that the detection of long-term trends is complicated by the quality of records prior to routine satellite observations. The summary also states that there is no clear trend in the annual worldwide number of tropical cyclones.
Additional anticipated effects include sea level rise of 0.18 to 0.59 meters (0.59 to 1.9 ft) in 2090-2100 relative to 1980-1999,  repercussions to agriculture, possible slowing of the thermohaline circulation, reductions in the ozone layer, increasingly intense (but less frequent) hurricanes and extreme weather events, lowering of ocean pH, and the spread of diseases such as malaria and dengue fever. One study predicts 18% to 35% of a sample of 1,103 animal and plant species would be extinct by 2050, based on future climate projections. However, few mechanistic studies have documented extinctions due to recent climate change and one study suggests that projected rates of extinction are uncertain.
Some economists have tried to estimate the aggregate net economic costs of damages from climate change across the globe. Such estimates have so far yielded no conclusive findings; in a survey of 100 estimates, the values ran from US$-10 per tonne of carbon (tC) (US$-3 per tonne of carbon dioxide) up to US$350/tC (US$95 per tonne of carbon dioxide), with a mean of US$43 per tonne of carbon (US$12 per tonne of carbon dioxide).
One widely publicized report on potential economic impact is the Stern Review. It suggests that extreme weather might reduce global gross domestic product by up to one percent, and that in a worst-case scenario global per capita consumption could fall 20 percent. The report's methodology, advocacy and conclusions have been criticized by many economists, primarily around the Review's assumptions of discounting and its choices of scenarios. Others have supported the general attempt to quantify economic risk, even if not the specific numbers.
Preliminary studies suggest that costs and benefits of mitigating global warming are broadly comparable in magnitude.
According to United Nations Environment Programme (UNEP), economic sectors likely to face difficulties related to climate change include banks, agriculture, transport and others. Developing countries dependent upon agriculture will be particularly harmed by global warming.
Adaptation and mitigation
The broad agreement among climate scientists that global temperatures will continue to increase has led some nations, states, corporations and individuals to implement actions to try to curtail global warming, adjust to it, or propose geoengineering to reverse it.
Many environmental groups encourage individual action against global warming, often by the consumer, but also by community and regional organizations. Others have suggested a quota on worldwide fossil fuel production, citing a direct link between fossil fuel production and CO2 emissions.
There has also been business action on climate change, including efforts at increased energy efficiency and limited moves towards use of alternative fuels. In January 2005 the European Union introduced its European Union Emission Trading Scheme, a greenhouse gas emissions trading scheme through which companies, in conjunction with government, agree to cap their emissions or to purchase credits from those below their allowances. Australia announced its Carbon Pollution Reduction Scheme in 2008. United States President Barack Obama has announced he will introduce an economy wide cap and trade scheme.
The world's primary international agreement on combating global warming is the Kyoto Protocol, an amendment to the UNFCCC negotiated in 1997. The Protocol now covers more than 160 countries globally and over 55 percent of global greenhouse gas emissions. Only the United States and Kazakhstan have not ratified the treaty, with the United States historically being the world's largest emitter of greenhouse gas. This treaty expires in 2012, and international talks began in May 2007 on a future treaty to succeed the current one. China and India, though exempt from its provisions as developing countries, have ratified the Kyoto Protocol. China may have passed the U.S. in total annual greenhouse gas emissions according to some recent studies. Chinese Premier Wen Jiabao has called on the nation to redouble its efforts to tackle pollution and global warming.
Former U.S. President George W. Bush contended that the Kyoto Protocol is an unfair and ineffective means of addressing global climate change concerns, claiming it that it "exempts 80 percent of the world, including major population centers such as China and India, from compliance, and would cause serious harm to the U.S. economy." Bush instead promoted improved energy technology as a means to combat climate change, while various state and city governments within the United States have begun their own initiatives to indicate support and compliance with the Kyoto Protocol on a local basis, such as the Regional Greenhouse Gas Initiative. The U.S. Climate Change Science Program is a joint program of over 20 U.S. federal agencies working together to investigate climate change.
The IPCC's Working Group III is responsible for crafting reports that deal with the mitigation of global warming and analyzing the costs and benefits of different approaches. In the 2007 IPCC Fourth Assessment Report, they conclude that no one technology or sector can be completely responsible for mitigating future warming. They find there are key practices and technologies in various sectors, such as energy supply, transportation, industry, and agriculture, that should be implemented to reduced global emissions. They estimate that stabilization of carbon dioxide equivalent between 445 and 710 ppm by 2030 will result in between a 0.6 percent increase and three percent decrease in global gross domestic product. According to Working Group III, to limit temperature rise to 2 degrees Celsius, "developed countries as a group would need to reduce their emissions to below 1990 levels in 2020 (on the order of –10 percent to 40 percent below 1990 levels for most of the considered regimes) and to still lower levels by 2050 (40 percent (Sic. 80 percent in Box 13.7, p776) to 95 percent below 1990 levels), even if developing countries make substantial reductions."
The slow pace of action to reduce greenhouse gas emissions have led some scientists, such as Ken Caldeira and the Nobel Prize winning Paul Crutzen to suggest geoengineering techniques, which can be employed to change the climate deliberately and thus control some of the effects of global warming.
Suggested techniques include:
- Solar radiation management - changing the Earth's albedo to alter the amount of sunlight that's reflected back into space. Techniques such as space sunshade, creating stratospheric sulfur aerosols and cool roof technology all fall into this category.
- Greenhouse gas remediation - techniques such as biomass energy with carbon capture and storage, using lasers to break up CFCs in the atmosphere and iron fertilisation of oceans to stimulate phytoplankton growth.
- Arctic geoengineering - typically seeking to preserve sea ice or adjust thermohaline circulation by using methods such as diverting rivers to keep warm water away from sea ice, or tethering icebergs to prevent them drifting into warmer waters and melting.
Economic and political debate
- See also: Scientific opinion on climate change, Climate change denial, List of countries by greenhouse gas emissions per capita, List of countries by carbon dioxide emissions per capita, List of countries by carbon dioxide emissions, and List of countries by ratio of GDP to carbon dioxide emissions
Increased publicity of the scientific findings surrounding global warming has resulted in political and economic debate. Poor regions, particularly Africa, appear at greatest risk from the projected effects of global warming, while their emissions have been small compared to the developed world. At the same time, developing country exemptions from provisions of the Kyoto Protocol have been criticized by the United States and Australia, and used as part of a rationale for continued non-ratification by the U.S. In the Western world, the idea of human influence on climate has gained wider public acceptance in Europe than in the United States.
The issue of climate change has sparked debate weighing the benefits of limiting industrial emissions of greenhouse gases against the costs that such changes would entail. There has been discussion in several countries about the cost and benefits of adopting alternative energy sources in order to reduce carbon emissions. Organizations and companies such as the Competitive Enterprise Institute and ExxonMobil have emphasized more conservative climate change scenarios while highlighting the potential economic cost of stricter controls. Likewise, various environmental lobbies and a number of public figures have launched campaigns to emphasize the potential risks of climate change and promote the implementation of stricter controls. Some fossil fuel companies have scaled back their efforts in recent years, or called for policies to reduce global warming.
Another point of contention is the degree to which emerging economies such as India and China should be expected to constrain their emissions. According to recent reports, China's gross national CO2 emissions may now exceed those of the U.S. China has contended that it has less of an obligation to reduce emissions since its per capita emissions are roughly one-fifth that of the United States. India, also exempt from Kyoto restrictions and another of the biggest sources of industrial emissions, has made similar assertions. The U.S. contends that if it must bear the cost of reducing emissions, then China should do the same.
Related climatic issues
A variety of issues are often raised in relation to global warming. One is ocean acidification. Increased atmospheric CO2 increases the amount of CO2 dissolved in the oceans. CO2 dissolved in the ocean reacts with water to form carbonic acid, resulting in acidification. Ocean surface pH is estimated to have decreased from 8.25 near the beginning of the industrial era to 8.14 by 2004, and is projected to decrease by a further 0.14 to 0.5 units by 2100 as the ocean absorbs more CO2. Since organisms and ecosystems are adapted to a narrow range of pH, this raises extinction concerns, directly driven by increased atmospheric CO2, that could disrupt food webs and impact human societies that depend on marine ecosystem services.
Global dimming, the gradual reduction in the amount of global direct irradiance at the Earth's surface, may have partially mitigated global warming in the late 20th century. From 1960 to 1990 human-caused aerosols likely precipitated this effect. Scientists have stated with 66–90% confidence that the effects of human-caused aerosols, along with volcanic activity, have offset some of the global warming, and that greenhouse gases would have resulted in more warming than observed if not for these dimming agents.
Ozone depletion, the steady decline in the total amount of ozone in Earth's stratosphere, is frequently cited in relation to global warming. Although there are areas of linkage, the relationship between the two is not strong.
Notes and references
- ^ "Summary for Policymakers" (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change (2007-02-05). Retrieved on 2007-02-02. "The updated hundred-year linear trend (1906 to 2005) of 0.74 °C [0.56 °C to 0.92 °C] is therefore larger than the corresponding trend for 1901 to 2000 given in the TAR of 0.6 °C [0.4 °C to 0.8 °C]."
- ^ a b Global surface temperature is defined in the IPCC Fourth Assessment Report as the average of near-surface air temperature over land and sea surface temperature.
- ^ a b c d e f g h i "Summary for Policymakers" (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change (2007-02-05). Retrieved on 2007-02-02.
- ^ Hegerl, Gabriele C.; et al. (2007-05-07). "Understanding and Attributing Climate Change" (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change 690. Intergovernmental Panel on Climate Change. Retrieved on 2007-05-20. "Recent estimates (Figure 9.9) indicate a relatively small combined effect of natural forcings on the global mean temperature evolution of the seconds half of the twentieth century, with a small net cooling from the combined effects of solar and volcanic forcings"
- ^ Ammann, Caspar; et al. (2007-04-06). "Solar influence on climate during the past millennium: Results from ransient simulations with the NCAR Climate Simulation Model" (PDF). Proceedings of the National Academy of Sciences of the United States of America 104 (10): 3713–3718. doi:10.1073/pnas.0605064103. PMID 17360418. http://www.pnas.org/cgi/reprint/104/10/3713.pdf. "However, because of a lack of interactive ozone, the model cannot fully simulate features discussed in (44)." "While the NH temperatures of the high-scaled experiment are often colder than the lower bound from proxy data, the modeled decadal-scale NH surface temperature for the medium-scaled case falls within the uncertainty range of the available temperature reconstructions. The medium-scaled simulation also broadly reproduces the main features seen in the proxy records." "Without anthropogenic forcing, the 20th century warming is small. The simulations with only natural forcing components included yield an early 20th century peak warming of ≈0.2 °C (≈1950 AD), which is reduced to about half by the end of the century because of increased volcanism.".
- ^ The 2001 joint statement was signed by the scientific academies of Australia, Belgium, Brazil, Canada, the Caribbean, China, France, Germany, India, Indonesia, Ireland, Italy, Malaysia, New Zealand, Sweden, and the UK. The 2005 statement added Japan, Russia, and the U.S. The 2007 statement added Mexico and South Africa. Professional societies include American Meteorological Society, American Geophysical Union, American Institute of Physics, American Astronomical Society, American Association for the Advancement of Science, Stratigraphy Commission of the Geological Society of London, Geological Society of America, American Chemical Society, and Engineers Australia.
- ^ "The Science Of Climate Change". Royal Society (May 2001). Retrieved on 2008-01-04.
- ^ "Joint science academies' statement: Global response to climate change". Royal Society (June 2005). Retrieved on 2008-01-04.
- ^ "Joint science academies' statement on growth and responsibility: sustainability, energy efficiency and climate protection" (PDF). Potsdam Institute for Climate Impact Research (May 2007). Retrieved on 2008-01-04.
- ^ "Don't fight, adapt". National Post (December 2007). Retrieved on 2007-11-18.
- ^ "A guide to facts and fictions about climate change". Royal Society (March 2005). Retrieved on 2007-11-18. ""However, the overwhelming majority of scientists who work on climate change agree on the main points""
- ^ "Beyond the Ivory Tower: The Scientific Consensus on Climate Change". Science (December 2004). Retrieved on 2008-01-04.
- ^ http://www.noaanews.noaa.gov/stories2009/20090126_climate.html
- ^ Lu, Jian; Gabriel A. Vecchi, Thomas Reichler (2007). "Expansion of the Hadley cell under global warming". Geophysical Research Letters 34: L06805. doi:10.1029/2006GL028443. http://www.atmos.berkeley.edu/~jchiang/Class/Spr07/Geog257/Week10/Lu_Hadley06.pdf. Retrieved on 6 December 2008.
- ^ "Joint science academies' statement: The science of climate change" (ASP). Royal Society (2001-05-17). Retrieved on 2007-04-01. "The work of the Intergovernmental Panel on Climate Change (IPCC) represents the consensus of the international scientific community on climate change science"
- ^ "Rising to the climate challenge". Nature 449 (7164): 755. 2007-10-18. doi:10.1038/449755a. http://www.nature.com/nature/journal/v449/n7164/full/449755a.html. Retrieved on 6 November 2007.
- ^ Gillett, Nathan P.; Dáithí A. Stone, Peter A. Stott, Toru Nozawa, Alexey Yu. Karpechko, Gabriele C. Hegerl, Michael F. Wehner & Philip D. Jones (2008). "Attribution of polar warming to human influence" (PDF). Nature Geoscience 1: 750. doi:10.1038/ngeo338. http://www.cru.uea.ac.uk/~nathan/pdf/ngeo338.pdf.
- ^ "The Discovery of Global Warming" (HTML). AIP (2008). Retrieved on 2008-10-14.
- ^ "IPCC WG1 AR4 Report — Chapter 1: Historical Overview of Climate Change Science" (PDF). IPCC WG1 AR4 Report p97 (pdf page 5 of 36). IPCC (2007). Retrieved on 2007-10-07. "To emit 240 W m–2, a surface would have to have a temperature of around –19 °C. This is much colder than the conditions that actually exist at the Earth’s surface (the global mean surface temperature is about 14 °C). Instead, the necessary –19 °C is found at an altitude about 5 km above the surface."
- ^ Note that the Greenhouse Effect produces a temperature increase of about 33 °C (59 °F) with respect to black body predictions and not a surface temperature of 33 °C (91 °F) which is 32 °F (0 °C) higher. The average surface temperature is about 14 °C (57 °F). Also note that both the Celsius and Fahrenheit temperatures are expressed to 2 significant figures even though the conversion formula produces 3.
- ^ Kiehl, J. T.; Kevin E. Trenberth (February 1997). "Earth’s Annual Global Mean Energy Budget" (PDF). Bulletin of the American Meteorological Society 78 (2): 197–208. doi:10.1175/1520-0477(1997)078<0197:EAGMEB>2.0.CO;2. http://www.atmo.arizona.edu/students/courselinks/spring04/atmo451b/pdf/RadiationBudget.pdf. Retrieved on 1 May 2006.
- ^ "Water vapour: feedback or forcing?". RealClimate (6 Apr 2005). Retrieved on 2006-05-01.
- ^ "Recent Climate Change - Atmosphere Changes, Science, Climate Change, U.S. EPA" (HTML). United States Environmental Protection Agency (2007). Retrieved on 2007-12-20.
- ^ Neftel, A., E. Moor, H. Oeschger, and B. Stauffer. (1985). "Evidence from polar ice cores for the increase in atmospheric CO2 in the past two centuries". Nature 315:45-47.
- ^ Pearson, Paul N.; Palmer, Martin R. (2000-08-17). "Atmospheric carbon dioxide concentrations over the past 60 million years" (abstract). Nature 406 (6797): 695–699. doi:10.1038/35021000. http://www.nature.com/nature/journal/v406/n6797/abs/406695a0.html.
- ^ "Summary for Policymakers". Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change (2001-01-20). Retrieved on 2007-01-18.
- ^ Prentice, I. Colin; et al. (2001-01-20). "22.214.171.124 SRES scenarios and their implications for future CO2 concentration". Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change. Retrieved on 2007-04-28.
- ^ "4.4.6. Resource Availability". IPCC Special Report on Emissions Scenarios. Intergovernmental Panel on Climate Change. Retrieved on 2007-04-28.
- ^ Svensmark, Henrik (February 2007). "Cosmoclimatology: a new theory emerges" (PDF). Astronomy & Geophysics 48 (1): 18–24. doi:10.1111/j.1468-4004.2007.48118.x. http://www.spacecenter.dk/research/sun-climate/Scientific%20work%20and%20publications/svensmark_2007cosmoClimatology.pdf.
- ^ Forster, Piers; et al. (2007-02-05). "Changes in Atmospheric Constituents and in Radiative Forcing" (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change 188-193. Intergovernmental Panel on Climate Change. Retrieved on 2007-09-17.
- ^ Bard, Edouard; Frank, Martin (2006-06-09). "Climate change and solar variability: What's new under the sun?" (PDF). Earth and Planetary Science Letters 248 (1-2): 1–14. doi:10.1016/j.epsl.2006.06.016. http://www.ifm-geomar.de/fileadmin/personal/fb1/p-oz/mfrank/Bard_and_Frank_2006.pdf. Retrieved on 17 September 2007.
- ^ Stott, Peter A.; et al. (2003-12-03). "Do Models Underestimate the Solar Contribution to Recent Climate Change?" (PDF). Journal of Climate 16 (24): 4079–4093. doi:10.1175/1520-0442(2003)016<4079:DMUTSC>2.0.CO;2. http://climate.envsci.rutgers.edu/pdf/StottEtAl.pdf. Retrieved on 16 April 2007.
- ^ Scafetta, Nicola; West, Bruce J. (2006-03-09). "Phenomenological solar contribution to the 1900–2000 global surface warming" (PDF). Geophysical Research Letters 33 (5): L05708. doi:10.1029/2005GL025539. L05708. http://www.fel.duke.edu/~scafetta/pdf/2005GL025539.pdf. Retrieved on 8 May 2007.
- ^ Marsh, Nigel; Henrik, Svensmark (November 2000). "Cosmic Rays, Clouds, and Climate" (PDF). Space Science Reviews 94 (1–2): 215–230. doi:10.1023/A:1026723423896. http://www.dsri.dk/~hsv/SSR_Paper.pdf. Retrieved on 17 April 2007.
- ^ Svensmark, Henrik (July 2000). "Cosmic Rays and Earth's Climate" (PDF). Space Science Reviews 93 (1-2): 175–185. doi:10.1023/A:1026592411634. http://winnetou.lcd.lu/physique/OSCIE2003/global_warming/Cosmic_rays_and_Earth_Climate_new_sven0606.pdf. Retrieved on 17 September 2007.
- ^ Hegerl, Gabriele C.; et al.. "Understanding and Attributing Climate Change" (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change 675. Intergovernmental Panel on Climate Change. Retrieved on 2008-02-01.
- ^ "Climate Change 2001:Working Group I: The Scientific Basis (Fig. 2.12)" (2001). Retrieved on 2007-05-08.
- ^ Ozone History
- ^ Foukal, Peter; et al. (2006-09-14). "Variations in solar luminosity and their effect on the Earth's climate." (abstract). Nature 443: 161. doi:10.1038/nature05072. http://www.nature.com/nature/journal/v443/n7108/abs/nature05072.html. Retrieved on 16 April 2007.
- ^ National Center for Atmospheric Research (2006-09-14). Changes in Solar Brightness Too Weak to Explain Global Warming. Press release. http://www.ucar.edu/news/releases/2006/brightness.shtml#. Retrieved on 2007-07-13.
- ^ Lockwood, Mike; Claus Fröhlich. "Recent oppositely directed trends in solar climate forcings and the global mean surface air temperature" (PDF). Proceedings of the Royal Society A 463: 2447. doi:10.1098/rspa.2007.1880. http://www.pubs.royalsoc.ac.uk/media/proceedings_a/rspa20071880.pdf. Retrieved on 21 July 2007. "Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified.".
- ^ Reply to Lockwood and Fröhlich - The persistent role of the Sun in climate forcing — Spacecenter
- ^ Richard Black (April 3, 2008). "'No Sun link' to climate change", BBC News Online.
- ^ T Sloan and A W Wolfendale (2008). "Testing the proposed causal link between cosmic rays and cloud cover". Environ. Res. Lett. 3: 024001. doi:10.1088/1748-9326/3/2/024001.
- ^ preprint of this paper can be found here
- ^ Meehl, Gerald A.; et al. (2005-03-18). "How Much More Global Warming and Sea Level Rise" (PDF). Science 307 (5716): 1769–1772. doi:10.1126/science.1106663. PMID 15774757. http://www.sciencemag.org/cgi/reprint/307/5716/1769.pdf. Retrieved on 11 February 2007.
- ^ Berger, A.; et al. (2005-12-10). "On the origin of the 100-kyr cycles in the astronomical forcing". Paleoceanography 20 (4): PA4019. doi:10.1029/2005PA001173. PA4019. http://www.agu.org/pubs/crossref/2005/2005PA001173.shtml. Retrieved on 5 November 2007.
- ^ Genthon, C.; et al. (1987-10-01). "Vostok Ice Core - Climatic response to CO2 and orbital forcing changes over the last climatic cycle" (abstract). Nature 329 (6138): 414–418. doi:10.1038/329414a0. http://www.nature.com/nature/journal/v329/n6138/abs/329414a0.html. Retrieved on 5 November 2007.
- ^ Alley, Richard B.; et al. (January 2002). "A northern lead in the orbital band: north-south phasing of Ice-Age events". Quaternary Science Reviews 21 (1-3): 431–441. doi:10.1016/S0277-3791(01)00072-5. http://www.ingentaconnect.com/content/els/02773791/2002/00000021/00000001/art00072. Retrieved on 5 November 2007.
- ^ Robock, Alan, and Clive Oppenheimer, Eds., 2003: Volcanism and the Earth’s Atmosphere, Geophysical Monograph 139, American Geophysical Union, Washington, DC, 360 pp.
- ^ "Stefan-Boltzmann Law", Britannica Online
- ^ a b Soden, Brian J.; Held, Isacc M. (2005-11-01). "An Assessment of Climate Feedbacks in Coupled Ocean–Atmosphere Models" (PDF). Journal of Climate 19 (14): 3354–3360. doi:10.1175/JCLI3799.1. http://www.gfdl.noaa.gov/reference/bibliography/2006/bjs0601.pdf. Retrieved on 21 April 2007. "Interestingly, the true feedback is consistently weaker than the constant relative humidity value, implying a small but robust reduction in relative humidity in all models on average" "clouds appear to provide a positive feedback in all models".
- ^ Panel on Climate Change Feedbacks, Climate Research Committee, National Research Council, 2004: Understanding Climate Change Feedbacks.
- ^ Stocker, Thomas F.; et al. (2001-01-20). "7.5.2 Sea Ice". Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change. Retrieved on 2007-02-11.
- ^ Sample, Ian (2005-08-11). "Warming Hits 'Tipping Point'", The Guardian. Retrieved on 18 January 2007.
- ^ Buesseler, Ken O.; et al. (2007-04-27). "Revisiting Carbon Flux Through the Ocean's Twilight Zone" (abstract). Science 316 (5824): 567–570. doi:10.1126/science.1137959. PMID 17463282. http://www.sciencemag.org/cgi/content/abstract/316/5824/567. Retrieved on 16 November 2007.
- ^ Working group I, section 126.96.36.199 of the 2007 IPPC page 243
- ^ Smith, Thomas M.; Reynolds, Richard W. (2005-05-15). "A Global Merged Land–Air–Sea Surface Temperature Reconstruction Based on Historical Observations (1880–1997)" (PDF). Journal of Climate 18 (12): 2021–2036. doi:10.1175/JCLI3362.1. ISSN 0894-8755. http://www.ncdc.noaa.gov/oa/climate/research/Smith-Reynolds-dataset-2005.pdf. Retrieved on 14 March 2007.
- ^ Rowan T. Sutton, Buwen Dong, Jonathan M. Gregory (2007). "Land/sea warming ratio in response to climate change: IPCC AR4 model results and comparison with observations". Geophysical Research Letters 34: L02701. doi:10.1029/2006GL028164. http://www.agu.org/pubs/crossref/2007/2006GL028164.shtml. Retrieved on 19 September 2007.
- ^ IPCC (2001). "Atmospheric Chemistry and Greenhouse Gases". Climate Change 2001: The Scientific Basis. Cambridge, UK: Cambridge University Press. http://www.grida.no/publications/other/ipcc_tar/?src=/CLIMATE/IPCC_TAR/WG1/127.htm.
- ^ Hansen, James E.; et al. (2006-01-12). "Goddard Institute for Space Studies, GISS Surface Temperature Analysis". NASA Goddard Institute for Space Studies. Retrieved on 2007-01-17.
- ^ "Global Temperature for 2005: second warmest year on record" (PDF). Climatic Research Unit, School of Environmental Sciences, University of East Anglia (2005-12-15). Retrieved on 2007-04-13.
- ^ "WMO STATEMENT ON THE STATUS OF THE GLOBAL CLIMATE IN 2005" (PDF). World Meteorological Organization (2005-12-15). Retrieved on 2007-04-13.
- ^ Changnon, Stanley A.; Bell, Gerald D. (2000). El Niño, 1997-1998: The Climate Event of the Century. London: Oxford University Press. ISBN 0195135520.
- ^ Mitchell, J. F. B.; et al. (2001-01-20). "188.8.131.52 Space-time studies". Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change. Retrieved on 2007-01-04.
- ^ Hansen J, Sato M, Ruedy R, Lacis A, Oinas V (August 2000). "Global warming in the twenty-first century: an alternative scenario". Proc. Natl. Acad. Sci. U.S.A. 97 (18): 9875–80. doi:10.1073/pnas.170278997. PMID 10944197.
- ^ Ruddiman, William F. (March 2005). "How Did Humans First Alter Global Climate?" (PDF). Scientific American 292 (3): 46–53. http://ccr.aos.wisc.edu/news/0305046.pdf. Retrieved on 5 March 2007.
- ^ Ruddiman, William F. (2005-08-01). Plows, Plagues, and Petroleum: How Humans Took Control of Climate. New Jersey: Princeton University Press. ISBN 0-691-12164-8.
- ^ Schmidt, Gavin; et al. (2004-12-10). "A note on the relationship between ice core methane concentrations and insolation" (abstract). Geophysical Research Letters 31 (23): L23206. doi:10.1029/2004GL021083. L23206. http://pubs.giss.nasa.gov/abstracts/2004/Schmidt_etal_2.html. Retrieved on 5 March 2007.
- ^ Hansen, James; et al. (2006-09-26). "Global temperature change" (PDF). PNAS 103 (39): 14288–14293. doi:10.1073/pnas.0606291103. PMID 17001018. http://www.pnas.org/cgi/reprint/103/39/14288.pdf. Retrieved on 20 April 2007.
- ^ Cohen, Anthony S.; et al. (February 2004). "Osmium isotope evidence for the regulation of atmospheric CO2 by continental weathering" (PDF). Geology 32 (2): 157–160. doi:10.1130/G20158.1. http://sheba.geo.vu.nl/~vonh/imagesanddata/data/Cohenetal2004.pdf. Retrieved on 4 March 2007.
- ^ "Chapter 7, "Couplings Between Changes in the Climate System and Biogeochemistry"" (PDF). Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change (2007-02-05). Retrieved on 2008-02-21.
- ^ Hansen, James (2000). "Climatic Change: Understanding Global Warming". One World: The Health & Survival of the Human Species in the 21st century. Health Press. Retrieved on 2007-08-18.
- ^ "Summary for Policymakers". Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change (2001-01-20). Retrieved on 2007-04-28.
- ^ Torn, Margaret; Harte, John (2006-05-26). "Missing feedbacks, asymmetric uncertainties, and the underestimation of future warming". Geophysical Research Letters 33 (10): L10703. doi:10.1029/2005GL025540. L10703. http://www.agu.org/pubs/crossref/2006/2005GL025540.shtml. Retrieved on 4 March 2007.
- ^ Harte, John; et al. (2006-10-30). "Shifts in plant dominance control carbon-cycle responses to experimental warming and widespread drought". Environmental Research Letters 1 (1): 014001. doi:10.1088/1748-9326/1/1/014001. 014001. http://www.iop.org/EJ/article/1748-9326/1/1/014001/erl6_1_014001.html. Retrieved on 2 May 2007.
- ^ Scheffer, Marten; et al. (2006-05-26). "Positive feedback between global warming and atmospheric CO2 concentration inferred from past climate change." (PDF). Geophysical Research Letters 33: L10702. doi:10.1029/2005gl025044. http://www.pik-potsdam.de/~victor/recent/scheffer_etal_T_CO2_GRL_in_press.pdf. Retrieved on 4 May 2007.
- ^ N. S. Keenlyside, M. Latif, J. Jungclaus, L. Kornblueh2, E. Roeckner (May 1, 2008). "Advancing decadal-scale climate prediction in the North Atlantic sector". Nature 453 (453): 84–88. doi:10.1038/nature06921. http://www.nature.com/nature/journal/v453/n7191/abs/nature06921.html. Retrieved on 6 July 2008.
- ^ Stocker, Thomas F.; et al. (2001-01-20). "7.2.2 Cloud Processes and Feedbacks". Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change. Retrieved on 2007-03-04.
- ^ Douglass, David H.; et al. (2007-12-05). "A comparison of tropical temperature trends with model predictions" (PDF). International Journal of Climatology 9999 (9999): 1693. doi:10.1002/joc.1651. http://icecap.us/images/uploads/DOUGLASPAPER.pdf. Retrieved on 12 May 2008.
- ^ Santer, B.D.; et al. (2008-10-10). "Consistency of modelled and observed temperature trends in the tropical troposphere" (PDF). International Journal of Climatology 28 (13): 1703. doi:10.1002/joc.1756. https://publicaffairs.llnl.gov/news/news_releases/2008/NR-08-10-05-article.pdf. Retrieved on 22 October 2008.
- ^ Macey, Jennifer (September 19, 2007). "Global warming opens up Northwest Passage", ABC News. Retrieved on 11 December 2007.
- ^ a b "Climate Change 2001: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change". Intergovernmental Panel on Climate Change (2001-02-16). Retrieved on 2007-03-14.
- ^ McMichael AJ, Woodruff RE, Hales S (2006). "Climate change and human health: present and future risks". Lancet 367 (9513): 859–69. doi:10.1016/S0140-6736(06)68079-3. PMID 16530580.
- ^ a b "Summary for Policymakers" (PDF). Climate Change 2007: Impacts, Adaptation and Vulnerability. Working Group II Contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report. Intergovernmental Panel on Climate Change (2007-04-13). Retrieved on 2007-04-28.
- ^ Knutson, Thomas R. (2008). "Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions". Nature Geoscience 1: 359. doi:10.1038/ngeo202.
- ^ edited Martin Parry ... (2007), "Chapter 8: Human Health", in Parry, M.L.; Canziani, O.F.; Palutikof, J.P. et al., Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge, United Kingdom and New York, NY, USA.: Cambridge University Press, ISBN 978 0521 88010-7, http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter8.pdf
- ^ United Nations Development Program (2008), "Summary: Fighting climate change", Human Solidarity in a divided world, Human Development Report (2007/2008 ed.), Palgrave Macmillan, ISBN 0-230-54704-4, http://hdr.undp.org/en/media/HDR_20072008_Summary_English.pdf
- ^ Thomas, Chris D.; et al. (2004-01-08). "Extinction risk from climate change" (PDF). Nature 427 (6970): 145–138. doi:10.1038/nature02121. http://www.geog.umd.edu/resac/outgoing/GEOG442%20Fall%202005/Lecture%20materials/extinctions%20and%20climate%20change.pdf. Retrieved on 18 March 2007.
- ^ McLaughlin, John F.; et al. (2002-04-30). "Climate change hastens population extinctions" (PDF). PNAS 99 (9): 6070–6074. doi:10.1073/pnas.052131199. PMID 11972020. http://www.nd.edu/~hellmann/pnas.pdf. Retrieved on 29 March 2007.
- ^ Botkin, Daniel B.; et al. (March 2007). "Forecasting the Effects of Global Warming on Biodiversity" (PDF). BioScience 57 (3): 227–236. doi:10.1641/B570306. http://www.imv.dk/Admin/Public/DWSDownload.aspx?File=%2FFiles%2FFiler%2FIMV%2FPublikationer%2FFagartikler%2F2007%2F050307_Botkin_et_al.pdf. Retrieved on 30 November 2007.
- ^ "At-a-glance: The Stern Review". BBC (2006-10-30). Retrieved on 2007-04-29.
- ^ Tol and Yohe (2006) "A Review of the Stern Review" World Economics 7(4): 233-50. See also other critiques in World Economics 7(4).
- ^ J. Bradford DeLong. "Do unto others...".
- ^ John Quiggin. "Stern and the critics on discounting".
- ^ Terry Barker (April 14, 2008). "Full quote from IPCC on costs of climate change". FT.com. Retrieved on 2008-04-14.
- ^ Dlugolecki, Andrew; et al. (2002). "Climate Risk to Global Economy" (PDF). CEO Briefing: UNEP FI Climate Change Working Group. United Nations Environment Programme. Retrieved on 2007-04-29.
- ^ "Thomas Schelling: Developing Countries Will Suffer Most from Global Warming" (PDF). Resources 164. Retrieved on 2008-03-01.
- ^ "Climate Control: a proposal for controlling global greenhouse gas emissions" (PDF). Sustento Institute. Retrieved on 2007-12-10.
- ^ Monbiot, George. "Rigged - The climate talks are a stitch-up, as no one is talking about supply." (HTML). Retrieved on 2007-12-22.
- ^ "Barack Obama and Joe Biden: New Energy for America". Retrieved on 2008-12-19.
- ^ "Kyoto Protocol Status of Ratification" (PDF). United Nations Framework Convention on Climate Change (2006-07-10). Retrieved on 2007-04-27.
- ^ Climate talks face international hurdles, by Arthur Max, Associated press, 5/14/07.
- ^ Sarah Yang, Media Relations (March 13, 2001). "New analysis finds alarming increase in expected growth of China CO2 emissions". UC Berkeley. Retrieved on 2008-03-10.
- ^ "Wen Urges Greater China Effort to Fight Pollution, July 10, 2007, Reuters, via planetark.com". Retrieved on 2007-07-27.
- ^ George W. Bush (March 13, 2001). "Text of a Letter from the President to Senators Hagel, Helms, Craig, and Roberts". Office of the Press Secretary. Retrieved on 2007-11-21.
- ^ State of the Union Address, retrieved 2008-01-28. "The United States is committed to strengthening our energy security and confronting global climate change. And the best way to meet these goals is for America to continue leading the way toward the development of cleaner and more energy-efficient technology."
- ^ "Regional Greenhouse Gas Initiative". Retrieved on 2006-11-07.
- ^ "Summary for Policymakers" (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change (2007-05-04). Retrieved on 2007-12-09.
- ^ Guptal, Sujata; et al. (2007-05-04). "Policies, Instruments and Co-operative Arrangements" (PDF). Policies, Instruments and Co-operative Arrangements. In Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change 21. Intergovernmental Panel on Climate Change. Retrieved on 2008-04-26. "..developed countries as a group would need to reduce their emissions to below 1990 levels in 2020 (on the order of –10% to 40% below 1990 levels for most of the considered regimes) and to still lower levels by 2050 (40% to 95% below 1990 levels), even if developing countries make substantial reductions."
- ^ Robert Kunzig (October 2008). "Geoengineering: How to Cool Earth--At a Price". Scientific American. Retrieved on 27 January 2009.
- ^ Gwynne Dyer (1 October 2008). "Time for geoengineering?". Japan Times. Retrieved on 27 January 2009.
- ^ Azar, Christian; Lindgren, Kristian; Larson, Eric; Möllersten, Kenneth (January 2006). "Carbon Capture and Storage From Fossil Fuels and Biomass – Costs and Potential Role in Stabilizing the Atmosphere". Climatic Change 74 (1-3): 47-79. http://www.ingentaconnect.com/content/klu/clim/2006/00000074/F0030001/00003484.
- ^ Stix, T.H. (7-9 Jun 1993). "Removal of chlorofluorocarbons from the troposphere" in Plasma Science, 1993..
- ^ Weart, Spencer (2006), "The Public and Climate Change", in Weart, Spencer, The Discovery of Global Warming, American Institute of Physics, http://www.aip.org/history/climate/Public.htm, retrieved on 14 April 2007
- ^ Revkin, Andrew (2007-04-01). "Poor Nations to Bear Brunt as World Warms", The New York Times. Retrieved on 2 May 2007.
- ^ Brahic, Catherine (2006-04-25). "China's emissions may surpass the US in 2007". New Scientist. Retrieved on 2007-05-02.
- ^ Crampton, Thomas (2007-01-04). "More in Europe worry about climate than in U.S., poll shows", International Herald Tribune. Retrieved on 14 April 2007.
- ^ "Summary of Findings". Little Consensus on Global Warming. Partisanship Drives Opinion. Pew Research Center (2006-07-12). Retrieved on 2007-04-14.
- ^ "EU agrees on carbon dioxide cuts", BBC (2007-03-09). Retrieved on 4 May 2007.
- ^ Begley, Sharon (2007-08-13). "The Truth About Denial", Newsweek. Retrieved on 13 August 2007.
- ^ Adams, David (2006-09-20). "Royal Society tells Exxon: stop funding climate change denial". The Guardian. Retrieved on 2007-08-09.
- ^ "Exxon cuts ties to global warming skeptics", MSNBC (2007-01-12). Retrieved on 2 May 2007.
- ^ Sandell, Clayton (2007-01-03). "Report: Big Money Confusing Public on Global Warming", ABC. Retrieved on 27 April 2007.
- ^ "Greenpeace: Exxon still funding climate skeptics", USA Today (2007-05-18). Retrieved on 9 July 2007.
- ^ Ceres (April 28, 2004). Global Warming Resolutions at U.S. Oil Companies Bring Policy Commitments from Leaders, and Record High Votes at Laggards. Press release. http://www.ceres.org/news/news_item.php?nid=56. Retrieved on 2007-07-27.
- ^ "China now top carbon polluter", BBC News (2008-04-14). Retrieved on 22 April 2008.
- ^ "China is biggest CO2 emitter : research", The Age (2008-04-15). Retrieved on 22 April 2008.
- ^ "Group: China tops world in CO2 emissions", Associated Press (2007-06-20). Retrieved on 16 October 2007.
- ^ "Group: China surpassed US in carbon emissions in 2006: Dutch report", Reuters (2007-06-20). Retrieved on 16 October 2007.
- ^ China: US should take lead on climate, by Michael Casey, Associated Press, via newsvine.com 12/7/07.
- ^ Glaciers in Retreat, by Somini Sengupta, 7/17/07, New York Times.
- ^ Chinese object to climate draft, BBC, 5/1/07; In Battle for U.S. Carbon Caps, Eyes and Efforts Focus on China,by Steven Mufson, Washington Post, 6/6/07.
- ^ "The Ocean and the Carbon Cycle". NASA (2005-06-21). Retrieved on 2007-03-04.
- ^ Jacobson, Mark Z. (2005-04-02). "Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry" (PDF). Journal of Geophysical Research 110 (D7): D07302. doi:10.1029/2004JD005220. D07302. http://www.stanford.edu/group/efmh/jacobson/2004JD005220.pdf. Retrieved on 28 April 2007.
- ^ Caldeira, Ken; Wickett, Michael E. (2005-09-21). "Ocean model predictions of chemistry changes from carbon dioxide emissions to the atmosphere and ocean". Journal of Geophysical Research 110 (C09S04): 1–12. doi:10.1029/2004JC002671. http://www.agu.org/pubs/crossref/2005/2004JC002671.shtml. Retrieved on 14 February 2006.
- ^ Raven, John A.; et al. (2005-06-30). "Ocean acidification due to increasing atmospheric carbon dioxide" (ASP). Royal Society. Retrieved on 2007-05-04.
- Association of British Insurers (2005-06) (PDF). Financial Risks of Climate Change. http://www.abi.org.uk/Display/File/Child/552/Financial_Risks_of_Climate_Change.pdf.
- Barnett, Tim P.; J. C. Adam, D. P. Lettenmaier (2005-11-17). "Potential impacts of a warming climate on water availability in snow-dominated regions" (abstract). Nature 438 (7066): 303–309. doi:10.1038/nature04141. http://www.nature.com/nature/journal/v438/n7066/abs/nature04141.html.
- Behrenfeld, Michael J.; Robert T. O'Malley, David A. Siegel, Charles R. McClain, Jorge L. Sarmiento, Gene C. Feldman, Allen G. Milligan, Paul G. Falkowski, Ricardo M. Letelier, Emanuel S. Boss (2006-12-07). "Climate-driven trends in contemporary ocean productivity" (PDF). Nature 444 (7120): 752–755. doi:10.1038/nature05317. http://www.icess.ucsb.edu/~davey/MyPapers/Behrenfeld_etal_2006_Nature.pdf.
- Choi, Onelack; Ann Fisher (May 2005). "The Impacts of Socioeconomic Development and Climate Change on Severe Weather Catastrophe Losses: Mid-Atlantic Region (MAR) and the U.S.". Climate Change 58 (1–2): 149–170. doi:10.1023/A:1023459216609. http://www.springerlink.com/content/m6308777613702q0/.
- Dyurgerov, Mark B.; Mark F. Meier (2005) (PDF). Glaciers and the Changing Earth System: a 2004 Snapshot. Institute of Arctic and Alpine Research Occasional Paper #58. ISSN 0069-6145. http://instaar.colorado.edu/other/download/OP58_dyurgerov_meier.pdf.
- Emanuel, Kerry A. (2005-08-04). "Increasing destructiveness of tropical cyclones over the past 30 years." (PDF). Nature 436 (7051): 686–688. doi:10.1038/nature03906. ftp://texmex.mit.edu/pub/emanuel/PAPERS/NATURE03906.pdf.
- Hansen, James; Larissa Nazarenko, Reto Ruedy, Makiko Sato, Josh Willis, Anthony Del Genio, Dorothy Koch, Andrew Lacis, Ken Lo, Surabi Menon, Tica Novakov, Judith Perlwitz, Gary Russell, Gavin A. Schmidt, Nicholas Tausnev (2005-06-03). "Earth's Energy Imbalance: Confirmation and Implications" (PDF). Science 308 (5727): 1431–1435. doi:10.1126/science.1110252. PMID 15860591. http://pangea.stanford.edu/research/Oceans/GES205/Hansen_Science_Earth's%20Energy%20Balance.pdf.
- Hinrichs, Kai-Uwe; Laura R. Hmelo, Sean P. Sylva (2003-02-21). "Molecular Fossil Record of Elevated Methane Levels in Late Pleistocene Coastal Waters". Science 299 (5610): 1214–1217. doi:10.1126/science.1079601. PMID 12595688.
- Hirsch, Tim (2006-01-11). "Plants revealed as methane source", BBC.
- Hoyt, Douglas V.; Kenneth H. Schatten (1993–11). "A discussion of plausible solar irradiance variations, 1700–1992". Journal of Geophysical Research 98 (A11): 18,895–18,906. doi:10.1029/93JA01944. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1993JGR....9818895H&db_key=AST&data_type=HTML&format=&high=448f267ff303582.
- A. V. Karnaukhov (2001). "Role of the Biosphere in the Formation of the Earth’s Climate: The Greenhouse Catastrophe" (PDF). Biophysics 46 (6). http://avturchin.narod.ru/Green.pdf.
- Kenneth, James P.; Kevin G. Cannariato, Ingrid L. Hendy, Richard J. Behl (2003-02-14). Methane Hydrates in Quaternary Climate Change: The Clathrate Gun Hypothesis. American Geophysical Union. https://www.agu.org/cgi-bin/agubooks?book=ASSP0542960.
- Keppler, Frank; Marc Brass, Jack Hamilton, Thomas Röckmann (2006-01-18). "Global Warming - The Blame Is not with the Plants", Max Planck Society.
- Lean, Judith L.; Y.M. Wang, N.R. Sheeley (2002–12). "The effect of increasing solar activity on the Sun's total and open magnetic flux during multiple cycles: Implications for solar forcing of climate" (abstract). Geophysical Research Letters 29 (24): 2224. doi:10.1029/2002GL015880. http://adsabs.harvard.edu/abs/2002GeoRL..29x..77L.
- Lerner, K. Lee; Brenda Wilmoth Lerner (2006-07-26). Environmental issues : essential primary sources.. Thomson Gale. ISBN 1414406258.
- McLaughlin, Joseph B.; Angelo DePaola, Cheryl A. Bopp, Karen A. Martinek, Nancy P. Napolilli, Christine G. Allison, Shelley L. Murray, Eric C. Thompson, Michele M. Bird, John P. Middaugh (2005-10-06). "Outbreak of Vibrio parahaemolyticus gastroenteritis associated with Alaskan oysters" (abstract). New England Journal of Medicine (New England Medical Society) 353 (14): 1463–1470. doi:10.1056/NEJMoa051594. PMID 16207848. http://content.nejm.org/cgi/content/abstract/353/14/1463. (online version requires registration)
- Muscheler, Raimund; Fortunat Joos, Simon A. Müller, Ian Snowball (2005-07-28). "Climate: How unusual is today's solar activity?" (PDF). Nature 436 (7012): 1084–1087. doi:10.1038/nature04045. http://www.cgd.ucar.edu/ccr/raimund/publications/Muscheler_et_al_Nature2005.pdf.
- Oerlemans, J. (2005-04-29). "Extracting a Climate Signal from 169 Glacier Records" (PDF). Science 308 (5722): 675–677. doi:10.1126/science.1107046. PMID 15746388. http://www.cosis.net/abstracts/EGU05/04572/EGU05-J-04572.pdf.
- Oreskes, Naomi (2004-12-03). "Beyond the Ivory Tower: The Scientific Consensus on Climate Change" (PDF). Science 306 (5702): 1686. doi:10.1126/science.1103618. http://www.sciencemag.org/cgi/reprint/306/5702/1686.pdf.
- Purse, Bethan V.; Philip S. Mellor, David J. Rogers, Alan R. Samuel, Peter P. C. Mertens, Matthew Baylis (February 2005). "Climate change and the recent emergence of bluetongue in Europe" (abstract). Nature Reviews Microbiology 3 (2): 171–181. doi:10.1038/nrmicro1090. http://www.nature.com/nrmicro/journal/v3/n2/abs/nrmicro1090_fs.html.
- Revkin, Andrew C (2005-11-05). "Rise in Gases Unmatched by a History in Ancient Ice", The New York Times.
- Ruddiman, William F. (2005-12-15). Earth's Climate Past and Future. New York: Princeton University Press. ISBN 0-7167-3741-8. http://www.whfreeman.com/ruddiman/.
- Ruddiman, William F. (2005-08-01). Plows, Plagues, and Petroleum: How Humans Took Control of Climate. New Jersey: Princeton University Press. ISBN 0-691-12164-8.
- Solanki, Sami K.; I.G. Usoskin, B. Kromer, M. Schussler, J. Beer (2004-10-23). "Unusual activity of the Sun during recent decades compared to the previous 11,000 years." (PDF). Nature 431: 1084–1087. doi:10.1038/nature02995. http://cc.oulu.fi/~usoskin/personal/nature02995.pdf.
- Solanki, Sami K.; I. G. Usoskin, B. Kromer, M. Schüssler, J. Beer (2005-07-28). "Climate: How unusual is today's solar activity? (Reply)" (PDF). Nature 436: E4–E5. doi:10.1038/nature04046. http://cc.oulu.fi/~usoskin/personal/sola_nature05.pdf.
- Sowers, Todd (2006-02-10). "Late Quaternary Atmospheric CH4 Isotope Record Suggests Marine Clathrates Are Stable". Science 311 (5762): 838–840. doi:10.1126/science.1121235. PMID 16469923.
- Svensmark, Henrik; Jens Olaf P. Pedersen, Nigel D. Marsh, Martin B. Enghoff, Ulrik I. Uuggerhøj (2007-02-08). "Experimental evidence for the role of ions in particle nucleation under atmospheric conditions". Proceedings of the Royal Society A (FirstCite Early Online Publishing) 463 (2078): 385–396. doi:10.1098/rspa.2006.1773. (online version requires registration)
- Walter, K. M.; S. A. Zimov, Jeff P. Chanton, D. Verbyla, F. S. Chapin (2006-09-07). "Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming". Nature 443 (7107): 71–75. doi:10.1038/nature05040.
- Wang, Y.-M.; J.L. Lean, N.R. Sheeley (2005-05-20). "Modeling the sun's magnetic field and irradiance since 1713" (PDF). Astrophysical Journal 625: 522–538. doi:10.1086/429689. http://climatesci.colorado.edu/publications/pdf/Wang_2005.pdf.
|Wikinews has related news: Climate change|
|Wikibooks has a book on the topic of|
- Intergovernmental Panel on Climate Change and UN Climate Panel Report's Key Findings.
- Nature Reports Climate Change
- The UK Met Office Hadley Centre site
- NOAA's Global Warming FAQ
- Discovery of Global Warming – An extensive introduction to the topic and the history of its discovery, written by Spencer R. Weart
- Caution urged on climate 'risks'
- Impact of Livestock on Global Warming (UN Report)
- Global Climate Change: NASA's Eyes on the Earth - Climate change overviews, key indicators, multimedia and current news.
- What Is Global Warming? – Shockwave presentation from National Geographic
- The EdGCM (Educational Global Climate Modelling) Project – A free research-quality simulation for students, educators, and scientists alike, with a user-friendly interface that runs on desktop computers
- DISCOVER Satellite-based ocean and climate data since 1979 from NASA
- The Pew Center on global climate change
- Global Warming Art
- Video of a talk by Warren Washington titled "The Evolution of Global Warming Science: From Ideas to Scientific Facts"
- Best Effort Global Warming Trajectories by Harvey Lam (Princeton University), The Wolfram Demonstrations Project.
- Science and Technology Sources on the Internet – Extensive commented list of Internet resources
- Union of Concerned Scientists Global Warming page
- Watch and read 'Tipping Point', Australian science documentary about effects of global warming on rare, common, and endangered wildlife
- United Nations University's 'Our World 2' Climate Change Video Briefs Accessed 22 January 2009
- Gateway to the UN System's Work on Climate Change