Every month, climate scientists make new discoveries that advance our understanding of climate change's causes and impacts. The research gives a clearer picture of the threats we already face and explores what's to come if we don't reduce emissions at a quicker pace.

我们的博客系列This Month in Climate Science, offers a snapshot of recent research, compiled from some of the leading peer-reviewed scientific journals. This edition explores studies published inJune and July 2020。(To get these updates delivered right to your inbox,sign up对于我们的热科学新闻通讯。）

最近的极端事件

在过去的两个月中，人们带来了令人震惊的气候变化的迹象，许多迹象符合温暖世界的预测。必威官网是真的吗

For example, this summer in the Arctic has beenone of extremes：

  • In only two days at the end of July, thelast fully intact ice shelfin the Canadian Arctic, the Milne Ice Shelf on Ellesmere Island, lost 40% of its area.
  • 在6月发生创纪录的热浪之后，西伯利亚爆发了大火，烧毁了一个地区比希腊大。Notably俄罗斯北极大约一半的大火在泥炭土中燃烧，不仅可以比其他土壤类型燃烧更长，而且在燃烧时释放大量的碳和甲烷。
  • Svalbard set an all-time热记录at 21.7 degrees C (71.1 degrees F). In Nunavut Canada, the temperature reached 21.9 degrees C (71.4 degrees F), which may be the highest everrecorded so far north。
  • 七月的北极海冰范围是当月卫星记录中最低的。
  • 这Northern Sea Route’s opening date – when it became ice-free — was theearliest on recordthis year.

北极并不孤单。在里面Middle Eastseveral countries experienced record highs. Baghdad reached 51.7 degrees C (125 degrees F). And aptly named Death Valley, California, may have reached the hottest temperature曾经记录过at 130 degrees F.

温度

  • 促进对气候敏感性的理解：必威官网是真的吗一种seminal paper使用多种证据来缩小平衡气候灵敏度的范围 - 随着工业前二氧化碳水平增加一倍，地球会变暖多少 - 这对于理解可能未来的温度变化至关重要。必威官网是真的吗大约40年前，科学家已经确定了C范围为1.5至4.5摄氏度（2.7至8.1摄氏度），但新研究发现它很可能在2.6至4.1摄氏度（4.7至7.4摄氏度）之间，与best estimate略高于3度C（5.4度F）。值得注意的是，科学家发现，变暖的最低和上层不太可能。
  • South Pole’s exceptional warming:研究人员have found that the South Pole has experienced record warming of roughly 0.61 degrees C (1.1 degrees F) per decade, three times the global average. They find that the warming wasdrivenby increasing sea surface temperatures in the western tropical Pacific.
  • 新的models running hot likely due to clouds:Some of the newest generation of earth systems models show更温暖associated with carbon dioxide concentrations, and are therefore running hotter than previous models. Areviewof various possible explanations finds that the models are likely doing so because of cloud feedbacks and cloud-aerosol interactions.

Emissions

  • 甲烷排放始终高：甲烷的全球排放量是一种比二氧化碳高28倍的温室气体，其记录在记录下达到最高水平。研究人员描述了他们从2000年至2017年全球甲烷预算的发现二文件。Since 2012, methane emissions have tracked the worst scenario of the Intergovernmental Panel on Climate Change.
  • Slow response of climate system to halting emissions:If one were to remove human-induced greenhouse gas emissions altogether, a新研究发现我们仍然可能不会在本世纪中叶之前看到明显的影响。这是因为气候系统的惯性和可变性。必威官网是真的吗温室气体排放的积累决定了我们目前的气候。必威官网是真的吗这意味着即使在进行了重大缓解工作之后，直到几十年来，表面温度也不会发生。即使完全消除了像黑碳这样的短暂气候刺激，十年来也不会有明显的影响必威官网是真的吗。作者指出，本文的发现可以帮助“管理我们的期望”。
  • Carbon removal via enhanced rock weathering:一种新研究finds significant potential for the application of enhanced silicate rock weathering on croplands. Enhanced weathering is a process which crushes rocks, in this case adding it to soil, and thereby accelerating rocks’ natural sequestration of carbon dioxide. They find the greatest potential in China, India and the US and the method could sequester 0.5-2 gigatonnes of carbon dioxide a year (equivalent to the排放量of Germany and Japan) at $80-180 per tonne of carbon dioxide.
  • 估计化石燃料排放的新方法：一个独立评估of emissions through NOAA’s air sampling network reveals higher fossil fuel emissions than estimated in the US national inventory, but within the bounds of error of another government estimation. The study demonstrates the feasibility of independent observations directly from atmospheric air samples, as opposed to accounting methods based on economic relationships and emissions factors, which are used in national inventories.

海洋Behavior

  • 一种rctic Ocean acidification worse than anticipated:一个新studyestimates20%more acidification in the Arctic Ocean over the century than previous studies. Ocean acidification can haveserious consequencesfor calcifying organisms, like mussels, as the shells break down in acidic waters.
  • 人类信号在北极海洋清新中：It has been established that the surface waters of the Arctic Ocean are fresher – less salty – than other oceans. This is due to freshwater runoff entering the oceans.研究人员have now demonstrated that this phenomenon is being driven by human-induced climate change and that we can soon expect to see changes beyond those experienced with past natural variability, with implications for ocean behavior.
  • Weaker ocean circulation could delay ice-free Arctic:Scientists对大西洋子午倾覆循环放缓的影响有了深入的了解，由于融化冰的淡水输入，它可能会减慢和减弱的海流。值得注意的是，他们发现这将使无冰的北极延迟六年，并在2061-2080到2061 - 2080年将无冰的平均表面温度降低0.2度C（0.36摄氏度）。

Extremes

  • Delayed monsoons:More than two-thirds of people on Earth live in areas impacted by monsoons. A new modelingstudyfinds that monsoons in nine regions across the Americas, Asia, Africa and Australia will be delayed up to a month by the end of the century, with the strongest delay over South America. For those regions with substantial delays, pre-monsoon precipitation will also decline. At the same time, more沉淀is more likely over a shorter period, which could exacerbate flooding. Many communities depend on the seasonality of monsoon rains for critical activities such as agriculture and hydropower.
  • 随着变暖的洪水显着增加：一种studyof the impacts of a high-emissions scenario (RCP 8.5) finds that without further adaptation or coastal protection, there would be 52% more of the global population (totally 2.5-4.1% of the population), 46% more global assets (totaling 10-20% of global GDP), and 48% more land at risk of flooding by the end of the century, compared to today’s risks of flooding. More than two-thirds of thefloodingis due to tide and storm events. Northwestern Europe and Asia are at greatest risk.
  • Unprecedented flooding in Europe:Using a new database,scientists现在发现，在过去500年中，欧洲的最后30年洪水是该地区洪水最高的时期之一。最近的洪水是exceptionalin terms of its extent, timing and associated air temperature.
  • 南美空前的极端降水：数据from tree rings were used to reconstruct hydroclimatic conditions since 1400 and show that the frequency of widespread severe droughts and extreme rainfall since the 1960s is unprecedented in South America. The researchers suggest that increased greenhouse gas emissions may cause more extreme rainfall and droughts in the region over the course of the century.
  • 一种cceleration of heatwaves:一种comprehensive assessmentof heatwaves finds that since the 1950s, the frequency, duration and cumulative heat of heatwaves has accelerated over many regions.
  • Human footprint in North American extreme rainfall:Scientistshave now established that human-induced climate change has contributed to extreme precipitation in North America. They further state that warming will lead to more frequent and intense precipitation extremes in the future.
  • 密苏里州上河干旱：新的researchhas established that the drought experienced in the Upper Missouri River Basin from 2000 to 2010 was potentially unprecedented in 1200 years and warming likely played a role in altering streamflow.
  • 北大西洋气候比我们想象的要可预必威官网是真的吗测：一种新文章finds that uncertainty in models related to North Atlantic wind patterns can be reduced significantly, increasing置信度in projections.

影响

  • Whales on the move:一个新studyof a decade’s worth of acoustic observations finds that the range of baleen whales in the North Atlantic Oceans has shifted, mirroring climatic shifts in the ocean and prey distribution. This has implications for protection plans as whales move into new areas known for shipping and fisheries.
  • 一种mphibians left vulnerable to changes in temperature and precipitation:水availability is critical for amphibians. Given changes in temperature and precipitation, a new paper suggests that water- and shade-seeking amphibians may be left with few ideal habitats. In areas where water may be available for amphibians,scientistshave found that future temperatures may be above what they can tolerate. On the other hand, where temperatures are more tolerable in the shade, these areas may be too dry.
  • 较早的弹簧为狼蜘蛛提供了时间额外的离合器：Spring is coming earlier to the high Arctic and snowmelt is advancing.Scientistshave now found that high-Arctic wolf spiders now have time to have a second clutch of eggs, like their neighbors at lower latitudes. This is the first evidence of invertebrates having additional clutches in response to warming. Given that wolf spiders are distributed widely, the authors posit that this could have implications for the broader food web.
  • 水温太热而无法容忍许多鱼类：一种studyof almost 700 species of marine and freshwater fish globally find that the stage during which fish species are mostvulnerable温度变化是当它们产卵或胚胎时。研究人员认为，到本世纪末，根据变暖的水平，有10％-60％的鱼类可能受到水温的影响，这些水温超出了它们可以忍受的生殖。
  • Decline of phytoplankton due to warming in the Northeast:研究人员在美国东北部的过去六十年中，发现了称为copepods的小水生甲壳类动物的丰度下降了50％，他们发现夏季天气的变化改变了对地表水的营养供应，这些养分无法维持这些更大，更营养的浮游植物。他们认为这可能有knock on impactsto the food web.
  • On the other hand, in the Arctic, more phytoplankton:In另一项研究，科学家发现，海冰损失增加了浮游植物，支持海洋食品网的微小生物，在1998年至2018年之间，主要产量增加了57％。未来的北极海可能更有生产力。
  • 红树林未能随着海平面上升而蓬勃发展：一种新研究发现红树林不可能随着海平面上升速度而增长，这在高排放局情况下可能会在30年内导致。红树林provide critical habitat to a wide range of species, provide storm surge protection and are an important carbon sink.
  • More crabs:由于海平面上升，在美国东南部，盐沼被淹没了更长的时间。最近studyfinds that a previously inconspicuous marsh crab is now reshaping the salt marsh ecosystem.
  • Too warm for tropical plant germination:一种recent study在1,312种来自锡花园的热带植物物种中，到2070年，所研究的一半以上的物种可能会经历高于其发芽的最佳温度，而有20％的物种的风险超过了其最高发芽温度。最接近赤道的人最脆弱。
  • Near extinction of polar bears by the end of the century:Polar bears depend on sea ice to hunt.研究人员have now identified the number of days that polar bear subpopulations can fast and coupled this information with model projections of sea ice loss. They find that between 1979 and 2016 such thresholds may already have been exceeded in some populations, meaning that the number of days that the bears were forced to fast was more than what they were capable of. With high greenhouse gas emissions, by the end of the century “all but a few” high-Arctic subpopulations will no longer be able to繁殖或生存。
  • Ice-free conditions allow for Adelie penguin success:Researchhas now found that Adelie penguins are taking advantage of ice-free environments, which allow them to swim rather than walk, cutting down the time and energy spent on foraging. Their dive durations have declined and they capture more krill with each dive. As a result, their adult body mass, growth rates of chicks and breeding success have increased.
  • 更多黄热病：黄热病是由蚊子传播的，目前每年在非洲造成近80,000人丧生。一个新studyof climate impacts to yellow fever transmission finds that even in the least severe warming scenario, there is a high likelihood that annual deaths would increase due to warming by mid-century. The projections increase yellow fever for most African countries. The Central African Republic is one of the countries most likely to see an increase in transmission.
  • Expanded range of zika:Modelersstudied future transmissions risk of zika, which is carried by mosquitoes, and find risk beyond the current observed range. Specifically, new transmission risk could occur over southern and eastern Europe, the northern U.S., northern China and southern Japan in future climate scenarios.
  • 海狸进入北极苔原：Scientistshave documented that beavers are colonizing low Arctic tundra areas in Alaska and Canada and, as a result of their dams on lakes and streams, are creating expanded waterbodies, which could worsen permafrostthawing.
  • Central European forests left vulnerable by drought:In 2018, Central Europe witnessed one of its most severe summer drought and heat waves.新研究发现森林的持久干旱压力。作者认为，包括生态和经济上关键物种在内的森林容易受到昆虫和病原体攻击的影响，并且比以前认为的更容易受到伤害。
  • 热带亚洲森林更加常绿：一个新的建模studyhas found that by the end of the century, vegetation in tropical Asia will increasingly transition from deciduous to evergreen and grow in height. Their projections suggest that the vegetation will remain a carbon sink, although conversion of ecosystems poses a risk to the carbon sink.

Ice and Permafrost

  • 更多的降雨会导致更湿，更脆弱的多年冻土：一种新研究assessed rain-induced thaw in permafrost in the interior of Alaska, and found evidence of deeper thaw. The authors suggest that the projected increase in summer precipitation across most of the Arctic could lead to substantial permafrost thaw.
  • 永久冻土的二氧化碳被低估：研究人员have found that thawing permafrost soils can be flushed into water bodies, such as lakes and rivers, and subsequentlyrelease carbon dioxidewhen exposed to sunlight. This pathway for release of carbon dioxide can lead to 14% more emissions than current estimates, and models currently fail to incorporate such a feedback.
  • 格陵兰和南极洲最近的重大冰损失：新的estimatesfrom NASA’s ICESat and ICESat-2 satellites show that between 2003 and 2019, 320 gigatons (Gt) of ice per year (200 Gt from Greenland; 118 Gt from Antarctica) was lost, contributing to 14 mm (0.55 inches) of sea level rise. Losses surpassed any gains.
  • “令人震惊”的北极海冰覆盖范围：Scientistshave quantified the loss of Arctic sea-ice cover since 1979, finding that the twelve lowest extents of sea-ice cover on record occurred during the last twelve years and that sea-ice volume in September 2018 was three times lower than that of September 1979.
  • Decline of summer sea ice in the Weddell Sea, Antarctica:在2016 - 17年度，Weddell Sea Antarctica的夏季海冰几乎创下了纪录的低谷。Scientistsattribute the loss to the reappearance of an area of open water – called the Maud Rise polynya – which allowed for more absorption of solar radiation, which in turn increased ocean temperatures and slowed down the creation of new ice. At the same time, westerly winds carried sea ice from the area. The researchers estimate that the extent of summer sea ice in the Weddell Sea is now 1 million square kilometers less (twice thesize of Spain) than in 2013-14. Many species depend on sea ice for breeding and food, including penguins and seals.
  • 在过去的温暖时期，南极洲东部的冰撤退：先前的研究表明，东南极洲的冰盖在地球历史的前几个时期相对稳定。新的research, however, has found evidence of significant ice loss in East Antarctica during an interglacial period about 400,000 years ago, raising new questions about its stability. This finding could have majorimplications鉴于冰盖有多少冰，对于海平面上升。
  • Greenland’s warming rate signals abrupt climate change:一个新studyuses observations and climate models to place the current rate of warming in Greenland in the context of past changes in the paleoclimate record. The authors find that warming rates that were similar to today’s were accompanied by abrupt glacial episodes. They conclude by arguing that the abrupt rate of temperature change in the Arctic is comparable only to that of thelast ice age, and that models are underestimating the rapid rate of change in the region.