气候反馈

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文件:20200118 Global warming and climate change - vertical block diagram - causes effects feedback.svg
The primary causes[1] and the wide-ranging effects[2][3] of global warming and resulting climate change. Some effects constitute feedback mechanisms that intensify climate change and move it toward climate tipping points.[4]

Climate change feedbacks are important in the understanding of global warming because feedback processes amplify or diminish the effect of each climate forcing, and so play an important part in determining the climate sensitivity and future climate state. Feedback in general is the process in which changing one quantity changes a second quantity, and the change in the second quantity in turn changes the first. Positive (or reinforcing) feedback amplifies the change in the first quantity while negative (or balancing) feedback reduces it.[5]

Climate change feedbacks are important in the understanding of global warming because feedback processes amplify or diminish the effect of each climate forcing, and so play an important part in determining the climate sensitivity and future climate state. Feedback in general is the process in which changing one quantity changes a second quantity, and the change in the second quantity in turn changes the first. Positive (or reinforcing) feedback amplifies the change in the first quantity while negative (or balancing) feedback reduces it.

气候变化的反馈对于理解全球变暖非常重要,因为反馈过程放大或减弱了每个气候强迫力的影响,因此在决定气候敏感性和未来气候状态方面发挥着重要作用。一般来说,反馈是这样一个过程,即改变一个量变化为第二个量,而第二个量的变化又依次改变第一个量。正反馈(或强化反馈)放大了第一个量的变化,而负反馈(或平衡反馈)减小了变化。

The term "forcing" means a change which may "push" the climate system in the direction of warming or cooling.[6] An example of a climate forcing is increased atmospheric concentrations of greenhouse gases. By definition, forcings are external to the climate system while feedbacks are internal; in essence, feedbacks represent the internal processes of the system. Some feedbacks may act in relative isolation to the rest of the climate system; others may be tightly coupled;[7] hence it may be difficult to tell just how much a particular process contributes.[8]

The term "forcing" means a change which may "push" the climate system in the direction of warming or cooling. , p.9. Also available as PDF

An example of a climate forcing is increased atmospheric concentrations of greenhouse gases. By definition, forcings are external to the climate system while feedbacks are internal; in essence, feedbacks represent the internal processes of the system. Some feedbacks may act in relative isolation to the rest of the climate system; others may be tightly coupled; hence it may be difficult to tell just how much a particular process contributes.

“强迫”一词是指可能使气候系统朝着变暖或变冷方向“推动”的变化。,p. 9.气候强迫的一个例子是大气中温室气体浓度的增加。根据定义,强迫是外部的气候系统,而反馈是内部的; 本质上,反馈代表系统的内部过程。一些反馈可能相对孤立地作用于气候系统的其余部分; 其他的可能是紧密耦合的; 因此,很难确定一个特定的过程究竟贡献了多少。

Forcings and feedbacks together determine how much and how fast the climate changes. The main positive feedback in global warming is the tendency of warming to increase the amount of water vapor in the atmosphere, which in turn leads to further warming.[9] The main cooling response comes from the Stefan–Boltzmann law, the amount of heat radiated from the Earth into space changes with the fourth power of the temperature of Earth's surface and atmosphere. It is typically not considered a feedback. Observations and modelling studies indicate that there is a net positive feedback to warming.[10] Large positive feedbacks can lead to effects that are abrupt or irreversible, depending upon the rate and magnitude of the climate change.[11][7]

Forcings and feedbacks together determine how much and how fast the climate changes. The main positive feedback in global warming is the tendency of warming to increase the amount of water vapor in the atmosphere, which in turn leads to further warming. The main cooling response comes from the Stefan–Boltzmann law, the amount of heat radiated from the Earth into space changes with the fourth power of the temperature of Earth's surface and atmosphere. It is typically not considered a feedback. Observations and modelling studies indicate that there is a net positive feedback to warming. Large positive feedbacks can lead to effects that are abrupt or irreversible, depending upon the rate and magnitude of the climate change.

强迫和反馈共同决定了气候变化的程度和速度。全球变暖的主要正反馈是变暖趋势增加了大气中的水汽量,进而导致进一步变暖。冷却的主要反应来自斯蒂芬-波尔兹曼定律,从地球辐射到太空的热量随着地球表面和大气温度的四次方的变化而变化。它通常不被认为是一个反馈。观测和模拟研究表明,气候变暖存在净正反馈。大规模的正反馈可能导致突然或不可逆转的影响,这取决于气候变化的速度和程度。

Positive

Carbon cycle feedbacks

There have been predictions, and some evidence, that global warming might cause loss of carbon from terrestrial ecosystems, leading to an increase of [[atmospheric CO2|atmospheric 模板:CO2]] levels. Several climate models indicate that global warming through the 21st century could be accelerated by the response of the terrestrial carbon cycle to such warming.[12] All 11 models in the C4MIP study found that a larger fraction of anthropogenic CO2 will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO2 varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO2 levels led to an additional climate warming ranging between 0.1° and 1.5 °C. However, there was still a large uncertainty on the magnitude of these sensitivities. Eight models attributed most of the changes to the land, while three attributed it to the ocean.[13] The strongest feedbacks in these cases are due to increased respiration of carbon from soils throughout the high latitude boreal forests of the Northern Hemisphere. One model in particular (HadCM3) indicates a secondary carbon cycle feedback due to the loss of much of the Amazon Rainforest in response to significantly reduced precipitation over tropical South America.[14] While models disagree on the strength of any terrestrial carbon cycle feedback, they each suggest any such feedback would accelerate global warming.


There have been predictions, and some evidence, that global warming might cause loss of carbon from terrestrial ecosystems, leading to an increase of atmospheric levels. Several climate models indicate that global warming through the 21st century could be accelerated by the response of the terrestrial carbon cycle to such warming. All 11 models in the C4MIP study found that a larger fraction of anthropogenic CO2 will stay airborne if climate change is accounted for. By the end of the twenty-first century, this additional CO2 varied between 20 and 200 ppm for the two extreme models, the majority of the models lying between 50 and 100 ppm. The higher CO2 levels led to an additional climate warming ranging between 0.1° and 1.5 °C. However, there was still a large uncertainty on the magnitude of these sensitivities. Eight models attributed most of the changes to the land, while three attributed it to the ocean. The strongest feedbacks in these cases are due to increased respiration of carbon from soils throughout the high latitude boreal forests of the Northern Hemisphere. One model in particular (HadCM3) indicates a secondary carbon cycle feedback due to the loss of much of the Amazon Rainforest in response to significantly reduced precipitation over tropical South America. While models disagree on the strength of any terrestrial carbon cycle feedback, they each suggest any such feedback would accelerate global warming.

有预测和一些证据表明,全球变暖可能导致陆地生态系统中碳的丧失,从而导致大气层水平的上升。一些气候模型表明,21世纪全球变暖可能会因陆地碳循环对这种变暖的反应而加速。C4MIP 研究中的所有11个模型都发现,如果考虑到气候变化,更大比例的人为二氧化碳将停留在空气中。到二十一世纪末,两种极端模型的额外二氧化碳含量在20至200ppm 之间变化,大多数模型的二氧化碳含量在50至100ppm 之间。较高的二氧化碳水平导致了额外的气候变暖,变暖幅度在0.1 ° c 到1.5 ° c 之间。然而,这些敏感性的程度仍然存在很大的不确定性。八个模型将大部分变化归因于陆地,而三个模型将其归因于海洋。在这些情况下,最强烈的反馈是由于整个高纬度北方森林北半球土壤中的碳呼吸增加。其中一个模式(HadCM3)指出了次级碳循环反馈,这是由于热带南美洲降水量显著减少而导致大部分亚马孙雨林减少所致。虽然模型不同意任何陆地碳循环反馈的强度,但它们都表明任何这样的反馈都会加速全球变暖。

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[15] 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).[16]

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 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).

根据 Bellamy 等人在《自然》杂志上发表的一篇论文,观察表明,在过去的25年里,英国的土壤正以每年400万吨的速度失去碳。他们指出,这些结果不太可能用土地用途的变化来解释。这样的结果依赖于密集的抽样网络,因此无法在全球范围内获得。他们推算整个联合王国,估计每年损失1300万吨。这相当于联合王国根据《京都议定书》每年减少的二氧化碳排放量(每年1270万吨碳)。

It has also been suggested (by Chris Freeman) that the release of dissolved organic carbon (DOC) from peat bogs into water courses (from which it would in turn enter the atmosphere) constitutes a positive feedback for global warming. The carbon currently stored in peatlands (390–455 gigatonnes, one-third of the total land-based carbon store) is over half the amount of carbon already in the atmosphere.[17] DOC levels in water courses are observably rising; Freeman's hypothesis is that, not elevated temperatures, but elevated levels of atmospheric CO2 are responsible, through stimulation of primary productivity.[18][19]

It has also been suggested (by Chris Freeman) that the release of dissolved organic carbon (DOC) from peat bogs into water courses (from which it would in turn enter the atmosphere) constitutes a positive feedback for global warming. The carbon currently stored in peatlands (390–455 gigatonnes, one-third of the total land-based carbon store) is over half the amount of carbon already in the atmosphere. DOC levels in water courses are observably rising; Freeman's hypothesis is that, not elevated temperatures, but elevated levels of atmospheric CO2 are responsible, through stimulation of primary productivity.

另外,Chris Freeman 认为,溶解有机碳从泥炭沼泽中释放到水体中(进而进入大气层)对全球变暖是一个积极的反馈。目前在泥炭地中储存的碳(3900-4550亿吨,占陆地碳储存总量的三分之一)超过大气中碳含量的一半。水体中的 DOC 水平显著上升; 弗里曼的假设是,不是温度升高,而是大气中二氧化碳水平升高,通过刺激初级生产力。

Tree deaths are believed to be increasing as a result of climate change, which is a positive feedback effect.[20]

文件:The methane climate feedback loop for natural ecosystems.jpg
Methane climate feedbacks in natural ecosystems.

Wetlands and freshwater ecosystems are predicted to be the largest potential contributor to a global methane climate feedback.[21] 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.[22]

Tree deaths are believed to be increasing as a result of climate change, which is a positive feedback effect. thumb|upright=1.5|Methane climate feedbacks in natural ecosystems. Wetlands and freshwater ecosystems are predicted to be the largest potential contributor to a global methane climate feedback. 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.

树木的死亡被认为是气候变化的结果,这是一个积极的反馈效应。自然生态系统中的甲烷气候反馈。预计湿地和淡水生态系统是全球甲烷气候反馈的最大潜在贡献者。长期变暖改变了淡水生态系统中与甲烷有关的微生物群落的平衡,因此它们产生更多的甲烷,而氧化成二氧化碳的比例相对较小。

Arctic methane release

文件:Permafrost thaw ponds in Hudson Bay Canada near Greenland.jpg
Photo shows what appears to be permafrost thaw ponds in Hudson Bay, Canada, near Greenland. (2008) Global warming will increase permafrost and peatland thaw, which can result in collapse of plateau surfaces.[23]

Warming is also the triggering variable for the release of carbon (potentially as methane) in the arctic.[24] Methane released from thawing permafrost such as the frozen peat bogs in Siberia, and from methane clathrate on the sea floor, creates a positive feedback.[25][26][27] In April 2019, Turetsky et al. reported permafrost was thawing quicker than predicted.[28][27] Recently the understanding of the climate feedback from permafrost improved, but potential emissions from the subsea permafrost remain unknown and are - like many other soil carbon feedbacks[29] - still absent from most climate models.[30]

thumb|upright=1.5|Photo shows what appears to be permafrost thaw ponds in Hudson Bay, Canada, near Greenland. (2008) Global warming will increase permafrost and peatland thaw, which can result in collapse of plateau surfaces.

Warming is also the triggering variable for the release of carbon (potentially as methane) in the arctic. Methane released from thawing permafrost such as the frozen peat bogs in Siberia, and from methane clathrate on the sea floor, creates a positive feedback. In April 2019, Turetsky et al. reported permafrost was thawing quicker than predicted. Recently the understanding of the climate feedback from permafrost improved, but potential emissions from the subsea permafrost remain unknown and are - like many other soil carbon feedbacks - still absent from most climate models.

= = = = 北极甲烷释放 = = = = 拇指 | 直立 = 1.5 | 照片显示了加拿大哈德逊湾附近格陵兰岛的冻土融化池。(2008)全球变暖将增加永久冻土和泥炭地融化,导致高原地表塌陷。变暖也是北极释放碳(可能是甲烷)的触发变量。西伯利亚冻土融化释放出的甲烷和海底甲烷气水包合物释放出的甲烷产生了正反馈。2019年4月,Turetsky 等人。报道的永冻层融化速度比预计的要快。近年来,对来自永久冻土的气候反馈的理解有所改善,但是来自海底永久冻土的潜在排放仍然是未知的,就像许多其他土壤碳反馈一样,在大多数气候模型中仍然缺乏。

Thawing permafrost peat bogs

Western Siberia is the world's largest peat bog, a one million square kilometer region of permafrost peat bog that was formed 11,000 years ago at the end of the last ice age. The melting of its permafrost is likely to lead to the release, over decades, of large quantities of methane. As much as 70,000 million tonnes of methane, an extremely effective greenhouse gas, might be released over the next few decades, creating an additional source of greenhouse gas emissions.[31] Similar melting has been observed in eastern Siberia.[32] Lawrence et al. (2008) suggest that a rapid melting of Arctic sea ice may start a feedback loop that rapidly melts Arctic permafrost, triggering further warming.[33][34] May 31, 2010. NASA published that globally "Greenhouse gases are escaping the permafrost and entering the atmosphere at an increasing rate - up to 50 billion tons each year of methane, for example - due to a global thawing trend. This is particularly troublesome because methane heats the atmosphere with 25 times the efficiency of carbon dioxide" (the equivalent of 1250 billion tons of 模板:CO2 per year).[35]


Western Siberia is the world's largest peat bog, a one million square kilometer region of permafrost peat bog that was formed 11,000 years ago at the end of the last ice age. The melting of its permafrost is likely to lead to the release, over decades, of large quantities of methane. As much as 70,000 million tonnes of methane, an extremely effective greenhouse gas, might be released over the next few decades, creating an additional source of greenhouse gas emissions. Similar melting has been observed in eastern Siberia. Lawrence et al. (2008) suggest that a rapid melting of Arctic sea ice may start a feedback loop that rapidly melts Arctic permafrost, triggering further warming. May 31, 2010. NASA published that globally "Greenhouse gases are escaping the permafrost and entering the atmosphere at an increasing rate - up to 50 billion tons each year of methane, for example - due to a global thawing trend. This is particularly troublesome because methane heats the atmosphere with 25 times the efficiency of carbon dioxide" (the equivalent of 1250 billion tons of per year).

西西伯利亚正在融化的永久冻土泥炭沼泽是世界上最大的泥炭沼泽,是一百万年前最后一个冰河时代末期形成的平方千米地区的永久冻土泥炭沼泽。几十年来,其永久冻土层的融化很可能导致大量甲烷的释放。在接下来的几十年里,可能会有多达700亿吨的甲烷被释放出来,这是一种极其有效的温室气体,从而产生额外的温室气体排放源。在东西伯利亚也发现了类似的融化现象。劳伦斯等人。(2008年)表明,北极海冰的快速融化可能会启动一个反馈循环,使北极永久冻土快速融化,引发进一步变暖。2010年5月31日。美国宇航局在全球范围内发表了这样一篇文章: “由于全球变暖的趋势,温室气体正在从永久冻土层中逸出,并以每年高达500亿吨的速度进入大气层。这是特别麻烦的,因为甲烷加热大气的效率是二氧化碳的25倍”(相当于每年12500亿吨)。

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 fossil fuels.[36]

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 fossil fuels.

2019年,一份名为“北极成绩单”的报告估计,目前北极永久冻土带的温室气体排放量几乎相当于俄罗斯或日本的排放量,或不到全球化石燃料排放量的10% 。

Hydrates
Hydrates

= = = = 水合物 = = =

Methane clathrate, also called methane hydrate, is a form of water ice that contains a large amount of methane within its crystal structure. Extremely large deposits of methane clathrate have been found under sediments on the sea and ocean floors of Earth. The sudden release of large amounts of natural gas from methane clathrate deposits, in a runaway global warming event, has been hypothesized as a cause of past and possibly future climate changes. The release of this trapped methane is a potential major outcome of a rise in temperature; it is thought that this might increase the global temperature by an additional 5° in itself, as methane is much more powerful as a greenhouse gas than carbon dioxide. The theory also predicts this will greatly affect available oxygen content of the atmosphere. This theory has been proposed to explain the most severe mass extinction event on earth known as the Permian–Triassic extinction event, and also the Paleocene-Eocene Thermal Maximum climate change event. In 2008, a research expedition for the American Geophysical Union detected levels of methane up to 100 times above normal in the Siberian Arctic, likely being released by methane clathrates being released by holes in a frozen 'lid' of seabed permafrost, around the outfall of the Lena River and the area between the Laptev Sea and East Siberian Sea.[37][38][39]

Methane clathrate, also called methane hydrate, is a form of water ice that contains a large amount of methane within its crystal structure. Extremely large deposits of methane clathrate have been found under sediments on the sea and ocean floors of Earth. The sudden release of large amounts of natural gas from methane clathrate deposits, in a runaway global warming event, has been hypothesized as a cause of past and possibly future climate changes. The release of this trapped methane is a potential major outcome of a rise in temperature; it is thought that this might increase the global temperature by an additional 5° in itself, as methane is much more powerful as a greenhouse gas than carbon dioxide. The theory also predicts this will greatly affect available oxygen content of the atmosphere. This theory has been proposed to explain the most severe mass extinction event on earth known as the Permian–Triassic extinction event, and also the Paleocene-Eocene Thermal Maximum climate change event. In 2008, a research expedition for the American Geophysical Union detected levels of methane up to 100 times above normal in the Siberian Arctic, likely being released by methane clathrates being released by holes in a frozen 'lid' of seabed permafrost, around the outfall of the Lena River and the area between the Laptev Sea and East Siberian Sea.

甲烷气水包合物,也被称为甲烷水合物,是一种在其晶体结构中含有大量甲烷的水冰。在地球海洋和海底的沉积物下发现了极大的甲烷气水包合物沉积物。在失控的全球变暖事件中,甲烷气水包合物沉积物突然释放出大量的天然气,这被假设为过去和可能的未来气候变化的原因。被困甲烷的释放是气温上升的一个潜在的主要结果; 据认为,这本身可能使全球气温增加5 ° ,因为甲烷作为一种温室气体的作用比二氧化碳强大得多。该理论还预测,这将极大地影响大气中的可用氧含量。这一理论被提出来解释地球上最严重的大规模灭绝事件,即二叠纪-三叠纪大灭绝事件,以及古新世-始新世最大气候变化事件。2008年,美国美国地球物理联盟海洋和大气管理局的一支研究探险队在西伯利亚北极地区探测到的甲烷含量高达正常水平的100倍,很可能是由海床永久冻土盖上的孔洞释放的甲烷包合物释放出来的,这些孔洞位于勒拿河的排水口附近,以及 Laptev Sea 和东西伯利亚海之间的地区。

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, eat the methane much fewer that 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.[40] A quarter of all marine methane is found in the region of Antarctica[41]

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, eat the methane much fewer that 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. A quarter of all marine methane is found in the region of Antarctica

2020年,在南极洲发现了第一次海底甲烷泄漏。科学家们还不确定是什么引起的。发现它的地区还没有明显变暖。它位于一座火山的侧面,但似乎不是从那里来的。食用甲烷的微生物,吃掉的甲烷比想象中少得多,研究人员认为这应该包括在气候模型中。他们还声称,关于南极洲的这个问题,还有更多的东西有待发现。南极洲地区发现了四分之一的海洋甲烷

Abrupt increases in atmospheric methane

Abrupt increases in atmospheric methane

= = = 大气中甲烷突然增加 = =

Literature assessments by the Intergovernmental Panel on Climate Change (IPCC) and the US Climate Change Science Program (CCSP) have considered the possibility of future projected climate change leading to a rapid increase in atmospheric methane. The IPCC Third Assessment Report, published in 2001, looked at possible rapid increases in methane due either to reductions in the atmospheric chemical sink or from the release of buried methane reservoirs. In both cases, it was judged that such a release would be "exceptionally unlikely"[42] (less than a 1% chance, based on expert judgement).[43] The CCSP assessment, published in 2008, concluded that an abrupt release of methane into the atmosphere appeared "very unlikely"[44] (less than 10% probability, based on expert judgement).[45] The CCSP assessment, however, noted that climate change would "very likely" (greater than 90% probability, based on expert judgement) accelerate the pace of persistent emissions from both hydrate sources and wetlands.[44]

Literature assessments by the Intergovernmental Panel on Climate Change (IPCC) and the US Climate Change Science Program (CCSP) have considered the possibility of future projected climate change leading to a rapid increase in atmospheric methane. The IPCC Third Assessment Report, published in 2001, looked at possible rapid increases in methane due either to reductions in the atmospheric chemical sink or from the release of buried methane reservoirs. In both cases, it was judged that such a release would be "exceptionally unlikely" (less than a 1% chance, based on expert judgement). The CCSP assessment, published in 2008, concluded that an abrupt release of methane into the atmosphere appeared "very unlikely" (less than 10% probability, based on expert judgement). The CCSP assessment, however, noted that climate change would "very likely" (greater than 90% probability, based on expert judgement) accelerate the pace of persistent emissions from both hydrate sources and wetlands.

政府间气候变化专门委员会政府间气候变化专门委员会(IPCC)和美国气候变化科学计划(CCSP)的文献评估已经考虑了未来预测的气候变化导致大气中甲烷迅速增加的可能性。2001年发表的政府间气候变化专门委员会第三次评估报告研究了由于大气化学汇减少或地下甲烷库释放而可能导致甲烷迅速增加的情况。在这两种情况下,人们都认为这样的释放是“极不可能的”(根据专家的判断,可能性小于1%)。2008年公布的 CCSP 评估得出结论认为,突然向大气中释放甲烷的可能性“非常小”(根据专家判断,可能性小于10%)。然而,CCSP 的评估指出,气候变化“很有可能”(根据专家判断,超过90% 的可能性)将加快水合物来源和湿地的持续排放速度。

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."[46] 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.[47]

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." 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.

2019年6月10日,Louise m. Farquharson 和她的团队报告说,他们对加拿大永久冻土层进行了为期12年的研究,”在我们的地点观测到的最大融化深度已经超过了预计到2090年发生的深度。在1990年至2016年期间,在陆地永久冻土中观测到高达4 ° c 的增长,随着北极年平均气温的增长速度是低纬度地区的两倍,这一趋势预计将继续下去确定新的热岩溶发育程度是困难的,但毫无疑问,这个问题是普遍存在的。Farquharson 和她的团队猜测,大约231,000平方英里(600,000平方公里)的永久冻土,或者说是永久冻土带的5.5% ,很容易受到地表快速融化的影响。

Decomposition

Organic matter stored in permafrost generates heat as it decomposes in response to the permafrost melting.[48] 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.[49]


Organic matter stored in permafrost generates heat as it decomposes in response to the permafrost melting. 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.

= = = 分解 = = = 存储在永久冻土中的有机物随着永久冻土的融化分解而产生热量。正如许多气候模型所预测的那样,随着热带地区变得越来越湿润,土壤可能会经历更大的呼吸和分解速率,从而限制了热带土壤的碳储存能力。

Peat decomposition

Peat decomposition

= = 泥炭分解 = =

Peat, occurring naturally in peat bogs, is a store of carbon significant on a global scale.[50] When peat dries it decomposes, and may additionally burn.[51] Water table adjustment due to global warming may cause significant excursions of carbon from peat bogs.[52] This may be released as methane, which can exacerbate the feedback effect, due to its high global warming potential.

Peat, occurring naturally in peat bogs, is a store of carbon significant on a global scale. When peat dries it decomposes, and may additionally burn. Water table adjustment due to global warming may cause significant excursions of carbon from peat bogs. This may be released as methane, which can exacerbate the feedback effect, due to its high global warming potential.

自然产生于泥炭沼泽中的泥炭,在全球范围内是一种重要的碳储存器。泥炭干了以后就会分解,并可能进一步燃烧。由于全球变暖引起的地下水位调整可能会导致泥炭沼泽中碳的显著迁移。由于甲烷具有较高的全球变暖潜能,它可能以甲烷的形式释放出来,从而加剧反馈效应。

Rainforest drying

Rainforest drying

= 雨林干涸 =

Rainforests, most notably tropical rainforests, are particularly vulnerable to global warming. There are a number of effects which may occur, but two are particularly concerning. Firstly, the drier vegetation may cause total collapse of the rainforest ecosystem.[53][54] For example, the Amazon rainforest would tend to be replaced by caatinga ecosystems. Further, even tropical rainforests ecosystems which do not collapse entirely may lose significant proportions of their stored carbon as a result of drying, due to changes in vegetation.[55][56]

Rainforests, most notably tropical rainforests, are particularly vulnerable to global warming. There are a number of effects which may occur, but two are particularly concerning. Firstly, the drier vegetation may cause total collapse of the rainforest ecosystem. For example, the Amazon rainforest would tend to be replaced by caatinga ecosystems. Further, even tropical rainforests ecosystems which do not collapse entirely may lose significant proportions of their stored carbon as a result of drying, due to changes in vegetation.

热带雨林,尤其是热带雨林,特别容易受到全球变暖的影响。有一些影响可能会发生,但其中两个特别令人担忧。首先,干燥的植被可能导致雨林生态系统的全面崩溃。例如,亚马孙雨林将会被 caatinga 生态系统所取代。此外,由于植被的变化,即使没有完全崩溃的热带雨林生态系统也可能因为干燥而失去其储存的大量碳。

Forest fires

Forest fires

= = 森林大火 = =

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.[57][58][59] Cook & Vizy also found that forest fires were likely in the Amazon Rainforest, eventually resulting in a transition to Caatinga vegetation in the Eastern Amazon region.[citation needed]

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. Cook & Vizy also found that forest fires were likely in the Amazon Rainforest, eventually resulting in a transition to Caatinga vegetation in the Eastern Amazon region.

政府间气候变化专门委员会第四次评估报告气候变化专门委员会预测,许多中纬度地区,如地中海欧洲,将经历降雨量减少和干旱风险增加,这反过来将允许森林火灾发生更大规模,更有规律。这会释放更多储存在大气中的碳,超过碳循环自然可以重新吸收的量,同时减少地球上的整个森林面积,形成一个积极的反馈循环。这种反馈回路的一部分是替代森林的更快增长和随着北纬地区变得更适合于维持森林的气候而向北迁移的森林。有一个问题是,燃烧森林等可再生燃料是否应被视为造成全球变暖的因素。库克和维齐还发现,亚马孙雨林可能发生森林火灾,最终导致亚马逊东部地区向卡廷加植被过渡。

Desertification

Desertification

= = 荒漠化 = =

Desertification is a consequence of global warming in some environments.[60] Desert soils contain little humus, and support little vegetation. As a result, transition to desert ecosystems is typically associated with excursions of carbon.

Desertification is a consequence of global warming in some environments. Desert soils contain little humus, and support little vegetation. As a result, transition to desert ecosystems is typically associated with excursions of carbon.

沙漠化是某些环境中全球变暖的结果。沙漠土壤中腐殖质含量很少,植被也很少。因此,向沙漠生态系统的转变通常伴随着碳的漂移。

Modelling results

Modelling results

= = 模拟结果 = =

The global warming projections contained in the IPCC's Fourth Assessment Report (AR4) include carbon cycle feedbacks.[61] Authors of AR4, however, noted that scientific understanding of carbon cycle feedbacks was poor.[62] 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.[61] 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.[61] The American Meteorological Society has commented that more research is needed to model the effects of carbon cycle feedbacks in climate change projections.[63]

The global warming projections contained in the IPCC's Fourth Assessment Report (AR4) include carbon cycle feedbacks. , in

Authors of AR4, however, noted that scientific understanding of carbon cycle feedbacks was poor., in . 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. 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. The American Meteorological Society has commented that more research is needed to model the effects of carbon cycle feedbacks in climate change projections.


政府间气候变化专门委员会第四次评估报告(AR4)中的全球变暖预测包括碳循环反馈。然而,在《第四次评估报告》的作者中指出,对碳循环反馈的科学理解在《第四次评估报告》中并不充分。第四次评估报告中的预测基于一系列温室气体排放情景,并表明20世纪末至21世纪末气温升高1.1至6.4摄氏度。这是“可能”的范围(大于66% 的概率) ,基于 IPCC 作者的专家判断。作者指出,“可能”范围的下端似乎比“可能”范围的上端受到更好的约束,部分原因是碳循环反馈。美国气象学会评论说,需要更多的研究来模拟气候变化预测中碳循环反馈的影响。

Isaken et al. (2010)[64] considered how future methane release from the Arctic might contribute to global warming. Their study suggested that if global methane emissions were to increase by a factor of 2.5 to 5.2 above (then) current emissions, 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.

Isaken et al. (2010) considered how future methane release from the Arctic might contribute to global warming. Their study suggested that if global methane emissions were to increase by a factor of 2.5 to 5.2 above (then) current emissions, 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.

伊斯肯等人。(2010年)考虑了未来北极甲烷的释放如何可能导致全球变暖。他们的研究表明,如果全球甲烷排放量比目前的排放量增加2.5到5.2倍,那么对辐射效应的间接贡献将分别为甲烷直接作用力的250% 和400% 。甲烷变暖的这种放大是由于大气化学的预计变化。

Schaefer et al. (2011)[65] considered how carbon released from permafrost might contribute to global warming. Their study 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. Schaefer et al. (2011) commented that this estimate may be low.

Schaefer et al. (2011)

considered how carbon released from permafrost might contribute to global warming. Their study 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. Schaefer et al. (2011) commented that this estimate may be low.

等人。(2011)考虑永久冻土释放的碳是如何导致全球变暖的。他们的研究基于中等温室气体排放情景(SRES A1B)预测永久冻土的变化。根据这项研究,到2200年,永久冻土反馈可能累计向大气中排放190(+/-64)亿吨碳。等人。(2011)评论说,这个估计可能偏低。

Implications for climate policy
Implications for climate policy

= = = 对气候政策的影响 = =

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.[66] 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 melting permafrost), then they may also underestimate the extent of emissions reductions necessary to meet a concentration or temperature target.

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. , in

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 melting permafrost), then they may also underestimate the extent of emissions reductions necessary to meet a concentration or temperature target.

气候变化反馈的不确定性对气候政策有影响。例如,碳循环反馈的不确定性可能会影响减少温室气体排放的目标。在排放目标中,排放目标往往基于大气温室气体浓度的目标稳定水平,或基于将全球变暖限制在特定程度的目标。这两个目标(浓度或温度)都需要了解未来碳循环的变化。如果模型不正确地预测未来碳循环的变化,那么浓度或温度目标可能会被错过。例如,如果模型低估了由于正反馈(例如,由于永久冻土融化)而释放到大气中的碳量,那么它们也可能低估了达到浓度或温度目标所必需的减排程度。

Cloud feedback

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 tend to trap more heat at the surface and therefore have a positive feedback, while high clouds normally reflect more sunlight from the top so they have a negative feedback. These details were poorly observed before the advent of satellite data and are difficult to represent in climate models.[67] 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.[68][69][70]


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 tend to trap more heat at the surface and therefore have a positive feedback, while high clouds normally reflect more sunlight from the top so they have a negative feedback. These details were poorly observed before the advent of satellite data and are difficult to represent in climate models. 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.

预计气候变暖将改变云的分布和类型。从下往上看,云层向地表释放红外线,从而产生升温效应; 从上往下看,云层反射阳光,向太空释放红外线,从而产生降温效应。净效应是升温还是降温取决于云的类型和高度等细节。低云倾向于在地表吸收更多的热量,因此具有正反馈,而高云通常反射更多来自顶部的阳光,因此具有负反馈。在卫星数据出现之前,这些细节观测不到,因此难以用气候模型来表示。全球气候模式显示出接近于零到中等强度的正净云反馈,但在最新一代全球气候模式中,有效的气候敏感性大大增加。相对于上一代模型,模型中云的物理表现的差异导致了气候敏感性的增强。

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.[71]

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.

2019年的一项模拟预测,如果温室气体达到目前大气二氧化碳水平的三倍,层积云可能会突然扩散,从而导致额外的全球变暖。

Gas release

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.[72][73] Others, such as dimethyl sulfide released from oceans, have indirect effects.[74]


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. Others, such as dimethyl sulfide released from oceans, have indirect effects.

气体释放可能受到全球变暖的影响,但对这种影响的研究还处于早期阶段。其中一些气体,如从泥炭或永久冻土融化释放的一氧化二氮,直接影响气候。其他的,比如从海洋中释放的二甲硫醚,有间接的影响。

Ice–albedo feedback

文件:Sea Ice MeltPonds.png
Aerial photograph showing a section of sea ice. The lighter blue areas are melt ponds and the darkest areas are open water; both have a lower albedo than the white sea ice. The melting ice contributes to 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.[77]


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.  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.  This is considered a faster feedback mechanism.Hansen, J., "2008: Tipping point: Perspective of a climatologist." , Wildlife Conservation Society/Island Press, 2008. Retrieved 2010.

当冰融化时,陆地或开阔水域取而代之。陆地和开阔水域的平均反射率都低于冰,因此吸收了更多的太阳辐射。这导致了更多的变暖,反过来又导致了更多的冰雪融化,这种循环还在继续。在全球变冷期间,额外的冰增加了反射率,从而减少了对太阳辐射的吸收,导致更多的冷却通过一个持续的循环。这被认为是一种更快的反馈机制,野生动物保护学会/岛屿出版社,2008。2010年。

文件:Seaice-1870-part-2009.png
1870–2009 Northern hemisphere sea ice extent in million square kilometers. Blue shading indicates the pre-satellite era; data then is less reliable. In particular, the near-constant level extent in Autumn up to 1940 reflects lack of data rather than a real lack of variation.

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.[78][79] 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.[80] The record losses of 2007 and 2008 may, however, be temporary.[81] 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.[82] The polar amplification of global warming is not predicted to occur in the southern hemisphere.[83] The Antarctic sea ice reached its greatest extent on record since the beginning of observation in 1979,[84] 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.[85]

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.. 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. The record losses of 2007 and 2008 may, however, be temporary. 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. The polar amplification of global warming is not predicted to occur in the southern hemisphere. The Antarctic sea ice reached its greatest extent on record since the beginning of observation in 1979, 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.

反照率的变化也是 IPCC 预测中东北半球极地气温将上升两倍于世界其他地区的主要原因,这一过程被称为极地放大。2007年9月,北极海冰面积达到1979年至2000年夏季平均最小面积的一半左右。.同样在2007年9月,北冰洋的冰层退缩到足够远的程度,使得北冰洋在有记载的历史上第一次成为可以通航的西北水道。然而,2007年和2008年的创纪录亏损可能只是暂时的。美国国家冰雪数据中心的 Mark Serreze 认为,2030年是对夏季北极冰盖可能无冰的“合理估计”。全球变暖的极地放大效应不会发生在中东南半球。自1979年开始观测以来,南极海冰达到了有记录以来的最大范围,但是南极海冰的增加超过了北极海冰的减少。全球海冰---- 北半球冰和南半球冰---- 的总和显然在减少。

Ice loss may have internal feedback processes, as melting of ice over land can cause eustatic sea level rise, potentially causing instability of ice shelves and inundating coastal ice masses, such as glacier tongues. Further, a potential feedback cycle exists due to earthquakes caused by isostatic rebound further destabilising ice shelves, glaciers and ice caps.

Ice loss may have internal feedback processes, as melting of ice over land can cause eustatic sea level rise, potentially causing instability of ice shelves and inundating coastal ice masses, such as glacier tongues. Further, a potential feedback cycle exists due to earthquakes caused by isostatic rebound further destabilising ice shelves, glaciers and ice caps.

冰的流失可能有内部反馈过程,因为陆地上冰的融化可能导致海平面升高,可能造成冰架的不稳定,并淹没沿海冰块,例如冰舌。此外,由于均衡反弹引起的地震进一步破坏冰架、冰川和冰盖的稳定,潜在的反馈周期存在。

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).[86]

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).

一些亚北极森林的冰反照率也在发生变化,落叶松林(它们在冬季脱落针叶,让阳光在春季和秋季反射到雪上)正在被云杉树(它们全年保留着黑色针叶)所取代。

Water vapor feedback

If the atmospheres are warmed, the saturation vapor pressure increases, and the amount 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.[67] Climate models incorporate this feedback. Water vapor feedback is strongly positive, with most evidence supporting a magnitude of 1.5 to 2.0 W/m2/K, sufficient to roughly double the warming that would otherwise occur.[87] Water vapor feedback is considered a faster feedback mechanism.[77]


If the atmospheres are warmed, the saturation vapor pressure increases, and the amount 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. Climate models incorporate this feedback. Water vapor feedback is strongly positive, with most evidence supporting a magnitude of 1.5 to 2.0 W/m2/K, sufficient to roughly double the warming that would otherwise occur. Water vapor feedback is considered a faster feedback mechanism.

如果大气层变暖,饱和蒸汽压就会增加,大气中的水蒸汽数量就会增加。由于水蒸气是一种温室气体,水蒸气含量的增加使得大气层进一步变暖; 这种变暖导致大气层保留更多的水蒸气(正反馈) ,以此类推,直到其他过程停止反馈循环。其结果是一个更大的温室效应比仅仅由于二氧化碳。虽然这种反馈过程会导致空气中绝对水分含量的增加,但由于空气变暖,相对湿度几乎保持不变,甚至略有下降。气候模型包含了这种反馈。水蒸气反馈是强烈的正反馈,大多数证据支持1.5到2.0 w/m2/k 的幅度,足以大致翻倍,否则就会发生变暖。水蒸气反馈被认为是一种更快的反馈机制。

Ocean-warming feedback

According to the U.S. National Oceanic and Atmospheric Administration:[88] Ocean warming provides a good example of a potential positive feedback mechanism. The oceans are an important sink for 模板:CO2 through absorption of the gas into the water surface. As 模板:CO2 increases, it increases the warming potential of the atmosphere. If air temperatures warm, it should warm the oceans. The ability of the ocean to remove 模板:CO2 from the atmosphere decreases with increasing temperature. Because of this, increasing 模板:CO2 in the atmosphere could have effects that actually intensify the increase in 模板:CO2 in the atmosphere.

According to the U.S. National Oceanic and Atmospheric Administration: Ocean warming provides a good example of a potential positive feedback mechanism. The oceans are an important sink for through absorption of the gas into the water surface. As increases, it increases the warming potential of the atmosphere. If air temperatures warm, it should warm the oceans. The ability of the ocean to remove from the atmosphere decreases with increasing temperature. Because of this, increasing in the atmosphere could have effects that actually intensify the increase in in the atmosphere.

= = = 海洋变暖反馈 = = = 根据美国美国国家海洋和大气管理局海洋和大气管理局: 海洋变暖提供了一个潜在的正反馈机制的很好的例子。海洋是通过吸收气体进入水面的一个重要的汇。随着温度的升高,它增加了大气的升温潜能。如果空气温度升高,海洋也会升温。海洋离开大气层的能力随着温度的升高而降低。正因为如此,大气层中温度的升高实际上会加剧大气层中温度的升高。

Negative

Negative

= 否定 =

Blackbody radiation

As the temperature of a black body increases, the emission of infrared radiation back into space increases with the fourth power of its absolute temperature according to Stefan–Boltzmann law.[89] This increases the amount of outgoing radiation as the Earth warms. It is called the Planck response, and sometimes considered a negative feedback (the Planck feedback).

As the temperature of a black body increases, the emission of infrared radiation back into space increases with the fourth power of its absolute temperature according to Stefan–Boltzmann law. This increases the amount of outgoing radiation as the Earth warms. It is called the Planck response, and sometimes considered a negative feedback (the Planck feedback).

= = = 黑体辐射 = = = = 黑体辐射随着黑体温度的升高,返回太空的红外线辐射根据 Stefan-Boltzmann 定律随着绝对温度的四次方而增加。随着地球变暖,辐射量也随之增加。这被称为普朗克反应,有时被认为是负反馈(普朗克反馈)。

Carbon cycle

Carbon cycle

= = 碳循环 = =

Le Chatelier's principle

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".[90] 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.

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". 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.

遵循勒夏忒列原理,地球碳循环的化学平衡将随着人类活动产生的二氧化碳排放而改变。主要的驱动因素是海洋,海洋通过所谓的溶解泵吸收人为的二氧化碳。目前,这仅占目前排放量的三分之一,但最终人类活动排放的大部分(约75%)二氧化碳将在几个世纪内溶解在海洋中: “公众讨论的化石燃料二氧化碳寿命的更好近似值可能是300年,再加上25% 的持续时间。”。然而,未来海洋上升的速度就不那么确定了,而且会受到全球变暖引起的分层现象的影响,还可能受到海洋温盐环流变化的影响。

Chemical weathering

Chemical weathering over the geological long term acts to remove CO2 from the atmosphere. With current global warming, weathering is increasing, demonstrating significant feedbacks between climate and Earth surface.[91] Biosequestration also captures and stores CO2 by biological processes. The formation of shells by organisms in the ocean, over a very long time, removes CO2 from the oceans.[92] The complete conversion of CO2 to limestone takes thousands to hundreds of thousands of years.[93]

Chemical weathering over the geological long term acts to remove CO2 from the atmosphere. With current global warming, weathering is increasing, demonstrating significant feedbacks between climate and Earth surface. Biosequestration also captures and stores CO2 by biological processes. The formation of shells by organisms in the ocean, over a very long time, removes CO2 from the oceans. The complete conversion of CO2 to limestone takes thousands to hundreds of thousands of years.

= = = = = = = = = = = = = 长期地质作用的化学风化从大气中除去二氧化碳。随着目前的全球变暖,风化作用正在加剧,显示了气候和地球表面之间的重要反馈作用。生物炭封存也通过生物过程捕获和储存二氧化碳。海洋中的生物在很长一段时间内形成的贝壳,将二氧化碳从海洋中移除。二氧化碳完全转化为石灰石需要数千到数十万年的时间。

Net primary productivity

Net primary productivity changes in response to increased CO2, as plants photosynthesis increased in response to increasing concentrations. However, this effect is swamped by other changes in the biosphere due to global warming.[94]

Net primary productivity changes in response to increased CO2, as plants photosynthesis increased in response to increasing concentrations. However, this effect is swamped by other changes in the biosphere due to global warming.

= = = = 净初级生产力 = = = = 净初级生产力随着二氧化碳浓度的增加而变化,因为植物的光合作用随着浓度的增加而增加。然而,由于全球变暖,这种影响被生物圈中的其他变化所淹没。

The climate change-exacerbated 2019–2020 Australian wildfires caused oceanic deposition of wildfire aerosols, enhancing marine productivity and thereby caused widespread phytoplankton blooms. While these increased oceanic carbon dioxide uptake, the amount likely pales in comparison to the ~715 million tons[95] of CO2 the fires emitted[96][97] and can模板:Additional citation needed contribute to ocean acidification[98] which, in turn, may induce toxic algal blooms[99] but is thought to generally closely follow future atmospheric CO2 concentrations as climate change feedbacks on ocean pH approximately cancel.[100]

The climate change-exacerbated 2019–2020 Australian wildfires caused oceanic deposition of wildfire aerosols, enhancing marine productivity and thereby caused widespread phytoplankton blooms. While these increased oceanic carbon dioxide uptake, the amount likely pales in comparison to the ~715 million tons of CO2 the fires emitted and can contribute to ocean acidification which, in turn, may induce toxic algal blooms but is thought to generally closely follow future atmospheric CO2 concentrations as climate change feedbacks on ocean pH approximately cancel.

气候变化加剧了2019-2020年澳大利亚的野火导致野火气溶胶在海洋中沉积,提高了海洋生产力,从而导致了大范围的浮游植物水华。虽然这些增加了海洋的二氧化碳吸收量,但与大火排放的大约7.15亿吨二氧化碳相比,这个数量可能相形见绌,并且可能导致海洋酸化,反过来,可能诱发有毒藻类的大量繁殖,但是由于气候变化对海洋 pH 值的反馈作用大致消失,人们普遍认为这与未来大气中的二氧化碳浓度密切相关。

Lapse rate

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.[101][citation needed] However, in regions with strong inversions, such as the polar regions, the lapse rate feedback can be positive because the surface warms faster than higher altitudes, resulting in inefficient longwave cooling.[101][102][103] 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.[104][105]


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. However, in regions with strong inversions, such as the polar regions, the lapse rate feedback can be positive because the surface warms faster than higher altitudes, resulting in inefficient longwave cooling. 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.

大气温度随着对流层高度的增加而降低。由于红外线的辐射随温度而变化,从相对寒冷的高层大气逃逸到太空的长波辐射比从低层大气向地面发射的要少。因此,温室效应的强度取决于大气温度随高度下降的速率。理论和气候模型都表明,全球变暖将降低温度随高度下降的速率,从而产生负递减率反馈,减弱温室效应。然而,在强烈反转的地区,例如极地地区,垂直速率反馈可能是正的,因为表面变暖的速度比高海拔地区快,导致长波冷却效率低下。温度随高度变化率的测量对观测中的微小误差非常敏感,因此很难确定模型是否与观测结果一致。

Impacts on humans

文件:Gore inconvenient truth loops.png
Feedback loops from the book Al Gore (2006). An inconvenient truth.

The graphic suggests that the overall effect of climate change upon human numbers and development will be negative.[106]

thumb|upright=1.55|Feedback loops from the book Al Gore (2006). An inconvenient truth. The graphic suggests that the overall effect of climate change upon human numbers and development will be negative.Gore, Al (2006). An inconvenient truth: the planetary emergency of global warming and what we can do about it. Emmaus, Pa., Melcher Media and Rodale Press.

= = 对人类的影响 = = 拇指 | 直立 = 1.55 | 来自 Al Gore (2006)一书的反馈循环。难以忽视的真相。该图表显示,气候变化对人口数量和发展的总体影响将是负面的。戈尔,艾尔(2006)。难以忽视的真相: 全球变暖的紧急情况以及我们能做些什么。埃梅厄斯,宾夕法尼亚州,梅尔彻媒体和罗代尔出版社。

See also

模板:Portal inline

  • Climate variability and change
  • Climate inertia
  • Complex system
  • Parametrization (climate)


See also

  • Climate variability and change
  • Climate inertia
  • Complex system
  • Parametrization (climate)

Notes

Notes

= 笔记 =

引用错误:Closing tag missing for <references>

}}

References

References

= 参考文献 =

  • IPCC AR4 WG1 (2007), Solomon, S.; Qin, D.; Manning, M.; Chen, Z.; Marquis, M.; Averyt, K.B.; Tignor, M.; Miller, H.L. (eds.), Climate Change 2007: The Physical Science Basis, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, ISBN 978-0-521-88009-1 (pb: 模板:ISBNT)
  • Zhou et al. (2020), Greater committed warming after accounting for the pattern effect, nature climate change.
  • (pb: )
  • Zhou et al. (2020), Greater committed warming after accounting for the pattern effect, nature climate change.


  • (pb: )
  • Zhou et al.(2020年) ,更大的承诺变暖后的模式效应,自然气候变化。

External links

  • Arctic permafrost leaking methane at record levels guardian.co.uk, Thursday 14 January 2010
  • CO2: The Thermostat that Controls Earth's Temperature by NASA, Goddard Institute for Space Studies, October, 2010
  • "Global warming 20 years later: tipping points near" (2008) PDF, address to National Press Club, and House Select Committee on Energy Independence & Global warming, Washington DC [44 pages]:
  • What are ‘climate feedbacks’? Big Picture TV video February 20, 2007, David Wasdell, Director of the Meridian Programme
  • How does climate change happen? (Part 1) Big Picture TV video February 20, 2007, David Wasdell, Director of the Meridian Programme
  • How does climate change happen? (Part 2) Big Picture TV video February 20, 2007, David Wasdell, Director of the Meridian Programme
  • 'Tipping point' risk for Arctic hotspot" BBC Jan 24, 2019

返回文章页面北极永久冻土层甲烷泄漏达到创纪录水平译者: leon921269二氧化碳: 控制地球温度的恒温器美国宇航局,戈达德太空研究所,2010年10月

  • “20年后的全球变暖: 临界点接近”(2008) PDF,致美国国家新闻俱乐部和众议院能源独立与全球变暖特别委员会,华盛顿特区[44页] :
  • 什么是‘气候反馈’?大画面电视视频2007年2月20日,大卫 · 沃斯戴尔,子午线项目主任
  • 气候变化是如何发生的?(一)大画面电视短片2007年2月20日,《子午线计划》主任 David Wasdell
  • 气候变化是如何发生的?(二)大画面电视短片2007年2月20日,子午线项目主任大卫 · 沃斯戴尔
  • 北极热点的“引爆点”风险”BBC 2019年1月24日

模板:Global Warming


Category:Climate change feedbacks Category:Effects of climate change Category:Feedback

类别: 气候变化反馈类别: 气候变化影响类别: 反馈


This page was moved from wikipedia:en:Climate change feedback. Its edit history can be viewed at 气候反馈/edithistory