Climate change feedbacks
Climate change feedbacks are
The main positive feedback in global warming is the tendency of warming to increase the amount of water vapor in the atmosphere (resulting in more
The main negative feedback or "cooling response" comes from the
Observations and modeling studies indicate that globally the positive feedbacks outweigh the negative feedbacks. Therefore, there is a net positive feedback to Earth's global warming.[3]: 82
Definition and terminology
In
A 2021
: 2222Here, external forcing refers to "a forcing agent outside the climate system causing a change in the climate system"[4]: 2229 that may push the climate system in the direction of warming or cooling.[12] External forcings may be human-caused (for example, greenhouse gas emissions or land use change) or natural (for example, volcanic eruptions).[4]: 2229
Positive feedbacks through the carbon cycle
The global warming projections contained in the IPCC's Fourth Assessment Report (AR4) include carbon cycle feedbacks.[13] Authors of AR4, however, noted that scientific understanding of carbon cycle feedbacks was poor.[14] Projections in AR4 were based on a range of greenhouse gas emissions scenarios, and suggested warming between the late 20th and late 21st century of 1.1 to 6.4 °C.[13] This is the "likely" range (greater than 66% probability), based on the expert judgement of the IPCC's authors. Authors noted that the lower end of the "likely" range appeared to be better constrained than the upper end of the "likely" range, in part due to carbon cycle feedbacks.[13] The American Meteorological Society has commented that more research is needed to model the effects of carbon cycle feedbacks in climate change projections.[15]
There have been predictions, and some evidence, that global warming might cause loss of carbon from
Observations show that soils in the U.K have been losing carbon at the rate of four million tonnes a year for the past 25 years[19] according to a paper in Nature by Bellamy et al. in September 2005, who note that these results are unlikely to be explained by land use changes. Results such as this rely on a dense sampling network and thus are not available on a global scale. Extrapolating to all of the United Kingdom, they estimate annual losses of 13 million tons per year. This is as much as the annual reductions in carbon dioxide emissions achieved by the UK under the Kyoto Treaty (12.7 million tons of carbon per year).[20]
It has also been suggested (by
Tree deaths are believed to be increasing as a result of climate change, which is a positive feedback effect.[24]
Wetlands and freshwater ecosystems are predicted to be the largest potential contributor to a global methane climate feedback.[25] Long-term warming changes the balance in the methane-related microbial community within freshwater ecosystems so they produce more methane while proportionately less is oxidised to carbon dioxide.[26]
Arctic methane release
Warming is also the triggering variable for the release of carbon (potentially as methane) in the arctic.
Thawing permafrost
Western Siberia is the world's largest
Researchers have also analysed how carbon released from permafrost might contribute to global warming.[40] A study from 2011 projected changes in permafrost based on a medium greenhouse gas emissions scenario (SRES A1B). According to the study, by 2200, the permafrost feedback might contribute 190 (+/- 64) gigatons of carbon cumulatively to the atmosphere.
In 2019, a report called " Arctic report card " estimated the current greenhouse gas emissions from Arctic permafrost as almost equal to the emissions of Russia or Japan or less than 10% of the global emissions from
The Sixth IPCC Assessment Report states that "projections from models of permafrost ecosystems suggest that future permafrost thaw will lead to some additional warming – enough to be important, but not enough to lead to a 'runaway warming' situation, where permafrost thaw leads to a dramatic, self-reinforcing acceleration of global warming."[42]
Hydrates
In 2020, the first leak of methane from the sea floor in Antarctica was discovered. The scientists are not sure what caused it. The area where it was found had not warmed yet significantly. It is on the side of a volcano, but it seems that it is not from there. The methane-eating microbes consume much less methane than was supposed, and the researchers think this should be included in climate models. They also claim that there is much more to discover about the issue in Antarctica.[46] A quarter of all marine methane is found in the region of Antarctica[47]
Abrupt increases in atmospheric methane
On 10 June 2019 Louise M. Farquharson and her team reported that their 12-year study into Canadian permafrost had "Observed maximum thaw depths at our sites are already exceeding those projected to occur by 2090. Between 1990 and 2016, an increase of up to 4 °C has been observed in terrestrial permafrost and this trend is expected to continue as Arctic mean annual air temperatures increase at a rate twice that of lower latitudes."[52] Determining the extent of new thermokarst development is difficult, but there is little doubt the problem is widespread. Farquharson and her team guess that about 231,000 square miles (600,000 square kilometers) of permafrost, or about 5.5% of the zone that is permafrost year-round, is vulnerable to rapid surface thawing.[53]
Decomposition
Organic matter stored in permafrost generates heat as it decomposes in response to the permafrost thawing.[54] The amount of carbon stored in the permafrost region is estimated to be around two times the amount of carbon that is in the Earth's atmosphere.[55] As the tropics get wetter, as many climate models predict, soils are likely to experience greater rates of respiration and decomposition, limiting the carbon storage abilities of tropical soils.[56]
Peat decomposition
Rainforest drying
Forest fires
The IPCC Fourth Assessment Report predicts that many mid-latitude regions, such as Mediterranean Europe, will experience decreased rainfall and an increased risk of drought, which in turn would allow forest fires to occur on larger scale, and more regularly. This releases more stored carbon into the atmosphere than the carbon cycle can naturally re-absorb, as well as reducing the overall forest area on the planet, creating a positive feedback loop. Part of that feedback loop is more rapid growth of replacement forests and a northward migration of forests as northern latitudes become more suitable climates for sustaining forests. There is a question of whether the burning of renewable fuels such as forests should be counted as contributing to global warming.
Desertification
Desertification is a consequence of global warming in some environments.[67] Desert soils contain little humus, and support little vegetation. As a result, transition to desert ecosystems is typically associated with excursions of carbon.
Positive feedbacks through other mechanisms
Water vapor feedback
If the atmospheres are warmed, the
Cloud feedback
Global warming is expected to change the distribution and type of clouds. 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. Low clouds are brighter and optically thicker, while high clouds are optically thin (transparent) in the visible and trap IR. Reduction of low clouds tends to increase incoming solar radiation and therefore have a positive feedback, while a reduction in high clouds (since they mostly just trap IR) would result in a negative feedback. These details were poorly observed before the advent of satellite data and are difficult to represent in climate models.[68] Global climate models were showing a near-zero to moderately strong positive net cloud feedback, but the effective climate sensitivity has increased substantially in the latest generation of global climate models. Differences in the physical representation of clouds in models drive this enhanced climate sensitivity relative to the previous generation of models.[71][72][73]
A 2019 simulation predicts that if greenhouse gases reach three times the current level of atmospheric carbon dioxide that stratocumulus clouds could abruptly disperse, contributing to additional global warming.[74][8]
Ice–albedo feedback
When 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.[75] During times of global cooling, additional ice increases the reflectivity, which reduces the absorption of solar radiation, resulting in more cooling through a continuing cycle.[76] This is considered a faster feedback mechanism.[70]
Albedo change is also the main reason why IPCC predict polar temperatures in the northern hemisphere to rise up to twice as much as those of the rest of the world, in a process known as polar amplification. In September 2007, the Arctic sea ice area reached about half the size of the average summer minimum area between 1979 and 2000.[77][78] Also in September 2007, Arctic sea ice retreated far enough for the Northwest Passage to become navigable to shipping for the first time in recorded history.[79] The record losses of 2007 and 2008 may, however, be temporary.[80] Mark Serreze of the US National Snow and Ice Data Center views 2030 as a "reasonable estimate" for when the summertime Arctic ice cap might be ice-free.[81] The polar amplification of global warming is not predicted to occur in the southern hemisphere.[82] The Antarctic sea ice reached its greatest extent on record since the beginning of observation in 1979,[83] but the gain in ice in the south is exceeded by the loss in the north. The trend for global sea ice, northern hemisphere and southern hemisphere combined is clearly a decline.[84]
Ice loss may have internal feedback processes, as melting of ice over land can cause
The ice–albedo in some sub-arctic forests is also changing, as stands of larch (which shed their needles in winter, allowing sunlight to reflect off the snow in spring and fall) are being replaced by spruce trees (which retain their dark needles all year).[85]
Gas release by various sources
Release of gases of biological origin may be affected by global warming, but research into such effects is at an early stage. Some of these gases, such as nitrous oxide released from peat or thawing permafrost, directly affect climate.[86][87] Others, such as dimethyl sulfide released from oceans, have indirect effects.[88]
A 2010 study suggested that if global methane emissions were to increase by a factor of 2.5 to 5.2 above (then) current emissions,[89] the indirect contribution to radiative forcing would be about 250% and 400% respectively, of the forcing that can be directly attributed to methane. This amplification of methane warming is due to projected changes in atmospheric chemistry.
Negative feedbacks
Planck feedback
As the temperature of a
The Planck feedback or
This blackbody radiation or Planck response has been identified as "the most fundamental feedback in the climate system".[93]: 19
Carbon cycle negative feedbacks
Negative climate feedbacks from Earth's carbon cycle are thought to be relatively insensitive to temperature changes. For this reason they are sometimes considered separately or disregarded in studies which aim to quantify climate sensitivity.[92] They are nevertheless significant feedbacks to anthropogenic CO2 emissions over time, and have influence on climate inertia and within more general studies of dynamic (time-dependent) climate change.[95]
Role of oceans
Following Le Chatelier's principle, the chemical equilibrium of the Earth's carbon cycle will shift in response to anthropogenic CO2 emissions. The primary driver of this is the ocean, which absorbs anthropogenic CO2 via the so-called solubility pump. At present this accounts for only about one third of the current emissions, but ultimately most (~75%) of the CO2 emitted by human activities will dissolve in the ocean over a period of centuries: "A better approximation of the lifetime of fossil fuel CO2 for public discussion might be 300 years, plus 25% that lasts forever".[96] However, the rate at which the ocean will take it up in the future is less certain, and will be affected by stratification induced by warming and, potentially, changes in the ocean's thermohaline circulation.
Chemical weathering
Primary production through photosynthesis
Mechanisms with positive or negative feedback
Lapse rate
The lapse rate is the rate at which an atmospheric variable, normally
The atmosphere's temperature decreases with height in the troposphere. Since emission of infrared radiation varies with temperature, longwave radiation escaping to space from the relatively cold upper atmosphere is less than that emitted toward the ground from the lower atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere's rate of temperature decrease with height. Both theory and climate models indicate that global warming will reduce the rate of temperature decrease with height, producing a negative lapse rate feedback that weakens the greenhouse effect.[104] 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.[93]: 25 [107]
Mathematical formulation of global energy imbalance
Earth is a
where ASR is the absorbed
In order to diagnose that behavior around a relatively stable equilibrium state, one may consider a perturbation to EEI as indicated by the symbol Δ. Such a perturbation is induced by a radiative forcing (ΔF) which can be natural or man-made. Responses within the system to either return back towards the stable state, or to move further away from the stable state are called feedbacks λΔT:
- .
Collectively the feedbacks are approximated by the linearized parameter λ and the perturbed temperature ΔT because all components of λ (assumed to be first-order to act independently and additively) are also functions of temperature, albeit to varying extents, by definition for a thermodynamic system:
- .
Some feedback components having significant influence on EEI are: = water vapor, = clouds, = surface albedo, = carbon cycle, = Planck response, and = lapse rate. All quantities are understood to be global averages, while T is usually translated to temperature at the surface because of its direct relevance to humans and much other life.[92]
The negative Planck response, being an especially strong function of temperature, is sometimes factored out to give an expression in terms of the relative feedback gains gi from other components:
- .
For example for the water vapor feedback.
Within the context of modern numerical climate modelling and analysis, the linearized formulation has limited use. One such use is to diagnose the relative strengths of different feedback mechanisms. An estimate of climate sensitivity to a forcing is then obtained for the case where the net feedback remains negative and the system reaches a new equilibrium state (ΔEEI=0) after some time has passed:[93]: 19–20
- .
Implications for climate policy
Uncertainty over climate change feedbacks has implications for climate policy. For instance, uncertainty over carbon cycle feedbacks may affect targets for reducing greenhouse gas emissions (climate change mitigation).[109] Emissions targets are often based on a target stabilization level of atmospheric greenhouse gas concentrations, or on a target for limiting global warming to a particular magnitude. Both of these targets (concentrations or temperatures) require an understanding of future changes in the carbon cycle. If models incorrectly project future changes in the carbon cycle, then concentration or temperature targets could be missed. For example, if models underestimate the amount of carbon released into the atmosphere due to positive feedbacks (e.g., due to thawing permafrost), then they may also underestimate the extent of emissions reductions necessary to meet a concentration or temperature target.[citation needed]
See also
- Climate variability and change
- Climate inertia
- Complex system
- Effects of climate change
- Parametrization (climate)
- Tipping points in the climate system
References
- ^ a b c "The Study of Earth as an Integrated System". nasa.gov. NASA. 2016. Archived from the original on November 2, 2016.
- ^ Fig. TS.17, Technical Summary, Sixth Assessment Report (AR6), Working Group I, IPCC, 2021, p. 96. Archived from the original on July 21, 2022.
- ^ a b Stocker, Thomas F.; Dahe, Qin; Plattner, Gian-Kaksper (2013). IPCC AR5 WG1. Technical Summary (PDF). Archived (PDF) from the original on 16 July 2023. See esp. TFE.6: Climate Sensitivity and Feedbacks at p. 82.
- ^ a b c d e IPCC, 2021: Annex VII: Glossary [Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V. Masson-Delmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 2215–2256, doi:10.1017/9781009157896.022.
- ISBN 978-92-9169-158-6.
- ^ IPCC. "Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Pg 53" (PDF).
- PMID 31776487.
- ^ PMID 35914185.
- ^ S2CID 252161375.
- ^ "8.6.3.1 Water Vapour and Lapse Rate – AR4 WGI Chapter 8: Climate Models and their Evaluation". ipcc.ch. Archived from the original on 2010-04-09. Retrieved 2010-04-23.
- ^ "Climate change and feedback loops" (PDF). National Oceanographic and Atmospheric Administration (NOAA). Archived (PDF) from the original on 25 July 2023.
- ^ US NRC (2012), Climate Change: Evidence, Impacts, and Choices / How much are human activities heating Earth, US National Research Council (US NRC), p.9. Also available as PDF Archived 2013-02-20 at the Wayback Machine
- ^ a b c Meehl, G.A.; et al., "Chapter 10: Global Climate Projections", Sec 10.5.4.6 Synthesis of Projected Global Temperature at Year 2100, archived from the original on 2018-11-04, retrieved 2013-02-01, in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
- ^ Solomon; et al., "Technical Summary", TS.6.4.3 Global Projections: Key uncertainties, archived from the original on 2018-11-03, retrieved 2013-02-01, in in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
- ^ AMS Council (20 August 2012), 2012 American Meteorological Society (AMS) Information Statement on Climate Change, Boston, MA, USA: AMS
- S2CID 2689847.
- S2CID 1614769.
- ^ "5.5C temperature rise in next century". The Guardian. 2003-05-29. Retrieved 2008-01-02.
- ^ Tim Radford (2005-09-08). "Loss of soil carbon 'will speed global warming'". The Guardian. Retrieved 2008-01-02.
- S2CID 4345985.
- S2CID 3152551.
- S2CID 4308328.
- ^ Connor, Steve (2004-07-08). "Peat bog gases 'accelerate global warming'". The Independent.
- ^ "Science: Global warming is killing U.S. trees, a dangerous carbon-cycle feedback". climateprogress.org.
- hdl:1874/366386.
- S2CID 220261158.
- doi:10.14430/arctic3332. Archived from the originalon 2014-08-10. Retrieved 2014-08-02.
- .
- S2CID 129667039.
- .
- ^ ISSN 0261-3077. Retrieved 2019-07-02.
- PMID 31040419.
- S2CID 227515903.
- ISSN 1748-9326.
- ^ Fred Pearce (2005-08-11). "Climate warning as Siberia melts". New Scientist. Retrieved 2007-12-30.
- ^ Ian Sample (2005-08-11). "Warming Hits 'Tipping Point'". Guardian. Archived from the original on 2005-11-06. Retrieved 2007-12-30.
- ^ "Permafrost Threatened by Rapid Retreat of Arctic Sea Ice, NCAR Study Finds" (Press release). UCAR. 10 June 2008. Archived from the original on 18 January 2010. Retrieved 2009-05-25.
- .
- ^ Cook-Anderson, Gretchen (2020-01-15). "Just 5 questions: What lies beneath". NASA Global Climate Change: Vital Signs of the Planet. Retrieved 2020-01-24.
- ^ KEVIN SCHAEFER; TINGJUN ZHANG; LORI BRUHWILER; ANDREW P. BARRETT (2011). "Amount and timing of permafrost carbon release in response to climate warming". Tellus Series B. 63 (2): 165–180. .
- ^ Freedman, Andrew (10 December 2019). "The Arctic may have crossed key threshold, emitting billions of tons of carbon into the air, in a long-dreaded climate feedback". The Washington Post. Retrieved 20 December 2019.
- ^ Canadell, J.G., P.M.S. Monteiro, M.H. Costa, L. Cotrim da Cunha, P.M. Cox, A.V. Eliseev, S. Henson, M. Ishii, S. Jaccard, C. Koven, A. Lohila, P.K. Patra, S. Piao, J. Rogelj, S. Syampungani, S. Zaehle, and K. Zickfeld, 2021: Chapter 5: Global Carbon and other Biogeochemical Cycles and Feedbacks. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 673–816, doi:10.1017/9781009157896.007., Page: FAQ 5.2
- ^ Connor, Steve (September 23, 2008). "Exclusive: The methane time bomb". The Independent. Retrieved 2008-10-03.
- ^ Connor, Steve (September 25, 2008). "Hundreds of methane 'plumes' discovered". The Independent. Retrieved 2008-10-03.
- ^ N. Shakhova; I. Semiletov; A. Salyuk; D. Kosmach; N. Bel'cheva (2007). "Methane release on the Arctic East Siberian shelf" (PDF). Geophysical Research Abstracts. 9: 01071.
- ^ Carrington, Damian (22 July 2020). "First active leak of sea-bed methane discovered in Antarctica". The Guardian. Retrieved 24 July 2020.
- ^ Cockburn, Harry (23 July 2020). "Climate crisis: First active leaks of methane found on Antarctic seabed". The Independent. Retrieved 24 July 2020.
- ^ IPCC (2001d). "4.14". In R.T. Watson; the Core Writing Team (eds.). Question 4. Climate Change 2001: Synthesis Report. A Contribution of Working Groups I, II, and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Print version: Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.. This version: GRID-Arendal website. Archived from the original on 2011-06-04. Retrieved 2011-05-18.
- ^ IPCC (2001d). "Box 2-1: Confidence and likelihood statements". In R.T. Watson; the Core Writing Team (eds.). Question 2. Climate Change 2001: Synthesis Report. A Contribution of Working Groups I, II, and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Print version: Cambridge University Press, Cambridge, U.K., and New York, N.Y., U.S.A.. This version: GRID-Arendal website. Archived from the original on 2011-06-04. Retrieved 2011-05-18.
- ^ a b Clark, P.U.; et al. (2008). "Executive Summary". Abrupt Climate Change. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research (PDF). U.S. Geological Survey, Reston, VA. p. 2. Archived from the original (PDF) on 2011-07-21. Retrieved 2011-05-18.
- ^ Clark, P.U.; et al. (2008). "Chapter 1: Introduction: Abrupt Changes in the Earth's Climate System". Abrupt Climate Change. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research (PDF). U.S. Geological Survey, Reston, VA. p. 12. Archived from the original (PDF) on 2011-07-21. Retrieved 2011-05-18.
- .
- ^ Currin, Grant (June 14, 2019). "Arctic Permafrost Is Going Through a Rapid Meltdown — 70 Years Early". news.yahoo.com. Retrieved 2020-01-24.
- PMID 18202646.
- PMID 34001617.
- ^ Hays, Brooks (2020-05-06). "Wetter climate to trigger global warming feedback loop in the tropics". UPI. Retrieved 2020-05-11.
- ^ "Peatlands and climate change". IUCN. 2017-11-06. Retrieved 2019-08-23.
- ISSN 1752-0894.
- doi:10.1038/ngeo331.
- .
- PMID 29492460.
- S2CID 83489971.
- PMID 28287104.
- ^ "Climate Change and Fire". David Suzuki Foundation. Archived from the original on 2007-12-08. Retrieved 2007-12-02.
- ^ "Global warming : Impacts: Forests". United States Environmental Protection Agency. 2000-01-07. Archived from the original on 2007-02-19. Retrieved 2007-12-02.
- Woods Hole Research Center. Archived from the originalon 2007-10-25. Retrieved 2007-12-02.
- S2CID 33033125.
- ^ .
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
- ^ "Science Magazine February 19, 2009" (PDF). Archived from the original (PDF) on 2010-07-14. Retrieved 2010-09-02.
- ^ a b Hansen, J., "2008: Tipping point: Perspective of a climatologist." Archived 2011-10-22 at the Wayback Machine, Wildlife Conservation Society/Island Press, 2008. Retrieved 2010.
- ISSN 1944-8007.
- ISSN 0261-3077. Retrieved 2020-06-19.
- PMID 32457461.
- S2CID 134307699.[verification needed]
- S2CID 197572148.
- ISBN 978-0-521-01495-3.
- ^ "The cryosphere today". University of Illinois at Urbana-Champaign Polar Research Group. Archived from the original on 2011-02-23. Retrieved 2008-01-02.
- ^ "Arctic Sea Ice News Fall 2007". National Snow and Ice Data Center. Archived from the original on 2007-12-23. Retrieved 2008-01-02..
- ^ "Arctic ice levels at record low opening Northwest Passage". Wikinews. September 16, 2007.
- ^ "Avoiding dangerous climate change" (PDF). The Met Office. 2008. p. 9. Archived from the original (PDF) on December 29, 2010. Retrieved August 29, 2008.
- ^ Adam, D. (2007-09-05). "Ice-free Arctic could be here in 23 years". The Guardian. Retrieved 2008-01-02.
- ^ Eric Steig; Gavin Schmidt (4 December 2004). "Antarctic cooling, global warming?". RealClimate. Retrieved 2008-01-20.
- ^ "Southern hemisphere sea ice area". Cryosphere Today. Archived from the original on 2008-01-13. Retrieved 2008-01-20.
- ^ "Global sea ice area". Cryosphere Today. Archived from the original on 2008-01-10. Retrieved 2008-01-20.
- ^ University of Virginia (March 25, 2011). "Russian boreal forests undergoing vegetation change, study shows". ScienceDaily.com. Retrieved March 9, 2018.
- doi:10.1038/ngeo434.
- ^ Caitlin McDermott-Murphy (2019). "No laughing matter". The Harvard Gazette. Retrieved 22 July 2019.
- S2CID 129266687.
- S2CID 17810925. Archived from the original(PDF) on 4 March 2016. Retrieved 1 February 2013.
- ^ a b Yang, Zong-Liang. "Chapter 2: The global energy balance" (PDF). University of Texas. Retrieved 2010-02-15.
- ^ .
- ^ .See Appendices A and B for a more detailed review of this and similar formulations
- ^ ISBN 978-0-309-09072-8.
- .
- .
- .
- .
- ^ "The Carbon Cycle - Earth Science - Visionlearning". Visionlearning.
- ^ "Prologue: The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate by David Archer". princeton.edu. Archived from the original on 2010-07-04. Retrieved 2010-08-09.
- S2CID 52214847.
- ISBN 978-0-521-83970-9.
- ISBN 978-0-495-01162-0.
- ^ "Introduction to climate dynamics and climate modelling - Water vapour and lapse rate feedbacks". www.climate.be. Retrieved 2023-08-28.
- ^ S2CID 2252857.
- PMID 29765038.
- S2CID 225410590.
- S2CID 10362192. Archived from the original(PDF) on 2010-07-14. Retrieved 2010-09-02.
- ^ Hansen, James; Sato, Makiko; Kharecha, Pushker; von Schuckmann, Karina (January 2012). "Earth's Energy Imbalance". NASA. Archived from the original on 2012-02-04.
- ^ Meehl, G.A., T.F. Stocker, W.D. Collins, P. Friedlingstein, A.T. Gaye, J.M. Gregory, A. Kitoh, R. Knutti, J.M. Murphy, A. Noda, S.C.B. Raper, I.G. Watterson, A.J. Weaver and Z.-C. Zhao, 2007: Chapter 10: Global Climate Projections. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. (Section 10.4.1 Carbon Cycle/Vegetation Feedbacks)
External links
- CO2: The Thermostat that Controls Earth's Temperature by NASA, Goddard Institute for Space Studies, October, 2010