新报告from the Intergovernmental Panel on Climate Change (IPCC) shows that half a degree of warming matters—a lot.

作为历史的一部分Paris Agreementon climate change, countries committed to keep global warming well below 2˚C (3.6˚F) above pre-industrial levels while trying to limit temperature increase to 1.5˚C (2.7˚F). Based on a request by governments, the IPCC, a collection of world’s leading climate scientists, took stock of how the impacts of a 1.5˚C temperature limit differ from 2˚C, as well as the differences between emissions pathways for achieving these two temperature goals.他们的发现表明即使有1.5度的变暖，世界也会面临严重的气候影响，并且随着2度的必威官网是真的吗影响，这种影响会变得明显恶化。世界已经目睹了大约1°C的温度升高，并有望耗尽碳预算到2030年，与1.5°C相关。

Here’s a breakdown of the differences between a 1.5˚C and a 2˚C world:

极端温度

Average and extreme temperatures will be higher in all inhabited areas under 2°C of warming versus 1.5°C. Forexample，在1.5°C的温暖下，世界上近14％的人口将在五年内至少暴露一次严重的热浪。相反，在2°C的温暖下，世界人口中有37％的人口将在五年内至少暴露于一次严重的热浪。

Drought

如果变暖仅限于1.5°C，干旱的可能性和水的风险可能会大大降低。例如，在地中海和南部非洲的2°C下，干旱幅度和频率增加的风险明显大于1.5°C。

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大量降水和洪水

High latitude and mountainous regions, as well as Eastern Asia and Eastern North America, are projected to experience heavier precipitation under 2°C of warming than under 1.5°C. While 1.5°C can lead to increased runoff and floods in some regions compared to today’s conditions, 2°C could lead to even more.

Ice-Free Arctic

With 1.5°C, the reportfinds很可能每100年一次有一个无海冰的夏天。在2°C，频率increases至少每10年一次。这个可导致为了吸收更多的热量，会影响海洋循环，并对北半球的冬季天气产生影响。

海平面上升

随着1.5°C的变暖，与1986 - 2005年的水平相比，2100的海平面上升将为2100米（1.3英尺）。在2°C下，在2100中为0.46 m（1.5 ft）。

随着温度升高，洪水的风险也更大。在2100年的1.5°C变暖时，最多可容纳6900万人的洪水（假设没有适应和当前人口）。在2°C的温暖下，最多可以暴露于7900万。

Also, if the rate of sea level rise is slower, there can be more opportunities for communities to adapt.

物种损失

在2ºC变暖时，全球18％的昆虫，16％的植物和8％的脊椎动物预计将损失一半以上的范围。使用1.5°C的变暖，昆虫的三分之二减少了，植物和脊椎动物的一半减少了。

Other factors that lead to losses of species, such as forest fires and the spread of pests and diseases, also decrease if warming stays at 1.5°C.

陆地生态系统

预计生态系统将随着更大的变暖而变化。为了example，在2°C的温暖下，预计地球的13％的土地面积被预测见证了生物群落的转变（例如从苔原变为森林）或转变。使用1.5°C的变暖，这种风险降低到地球土地面积的4％。

Under higher temperatures, permafrost is at a much更大的融化风险，这将导致其存储的碳释放到大气中。

With warming of 2°C, 35-47 percent of the Arctic’s permafrost would thaw by 2100, an area of land that is three-quarters the size of Australia. If warming is limited to 1.5°C, the extent of thawing permafrost drops to 4.8 million km2. or about 21-37 percent of the total permafrost area..

海洋

Ocean ecosystems are already transforming and will change dramatically with just 1.5°C of warming. However, limiting warming to 1.5°C can stave off many of the impacts that higher temperatures would bring.

例如，珊瑚礁预计将下降70-90％，变暖大于1.5°C。随着一半的变暖，预期损失超过99％。低纬度，酸化，死区和其他危险条件下的渔业生产率丧失预计会更明显，而变暖高于1.5°C。例如，报告中引用的一项研究发现，海洋渔业的全球年度捕捞量下降了150万吨，低于1.5°C。在2°C以下。损失增加到300万吨。

Food Security

在萨赫勒，南部非洲，地中海和亚马逊地区，粮食短缺的风险预计会低于1.5°C的变暖，而不是在变暖的2°C下。如果变暖保持在1.5°C，渔业和水产养殖的风险也较低。

健康

Risks to human health, including heat-related morbidity and mortality in urban areas, are lower with 1.5°C of warming than 2°C.

经济增长

Economic losses are greater as temperatures rise, with middle income countries (Africa, southeast Asia, India, Brazil, Mexico) projected to be affected the most. For example, if warming is limited to 1.5°C, global GDP losses will be 0.3 percent by 2100. With 2°C of warming, losses would be 0.5 percent.

How much harder is it to limit warming to 1.5˚C vs. 2˚C ?

Meeting both the 1.5°C and 2°C limit will require unprecedented transformation across all economies, industries and geographies.

为了limiting warming to 1.5°C with no or limited overshoot, the world will need to reduce its annual emissions to 25-30 GtCO2e on average in 2030. The world is currently on track to emit more than double this amount by 2030 (52-58 GtCO2e). Limiting warming to 2°C would require reducing annual emissions by about 20 percent below 2010 levels in 2030; for 1.5°C, emissions will need to drop by 40-50 percent. Carbon dioxide emissions will need to reach net-zero around 2050 to limit warming to 1.5°C and around 2075 for 2°C.

在1.5°C上瞄准景点

达到2°C将避免气候变化带来许多灾难性影响，但是与我们将全球变暖限制在1.5°C的情况下，后果将明显差。必威官网是真的吗随着温度的升高，适应需求也会增加。节省这一半学位将需要巨大的努力。但是，正如今天的报告所示，这项努力将非常值得更加安全的社区，生态系统和经济体的回报。