这个故事是德赢提款‘s Climate Change Survival Plan package. As time runs out to prevent climate catastrophe, we’re looking at what we need to do now to safeguard our future. Clickhere阅读整个系列。
We’re at a turning point: The choices that the world makes now will determine how livable the planet is later this century. We know what climate change looks like in 2021. This summer was the hottest on record; hundreds died in unprecedented heat in the Pacific Northwest, and there were widespread power outages in the Middle East, where temperatures topped 125 degrees Fahrenheit. In basements in New York City and subways in China, people were trapped by floods. Massive wildfires burned in Canada and Siberia and Greece. In Madagascar, after four years without rain, the country is facing the first famine caused entirely by climate change.
But this isn’t the “new normal.” As emissions keep growing, things can get much, much worse. The planet has heated up so far a little more than 1 degree Celsius. By the end of the century, we may have managed to limit warming to 1.5 degrees Celsius, the most ambitious goal in the Paris climate agreement. Or, if we’re slower to act, the average temperature may have soared up to 2 or 3 degrees Celsius, or more—differences that sound small, but in reality, will shape very different futures. (Consider the fact that 3 million years ago when the planet was hotter by 3 degrees Celsius, sea levels were as much as高50英尺，和giant camels lived in Arctic forests—not things that are going to happen this century but that illustrate the scale of what’s possible with a change of only a few degrees.)
Everything depends on how quickly businesses and governments and the rest of society change course this decade, and the next, and the next. “If we work around the edges of emissions reductions, kind of what we’re doing right now, let’s face it—we’ll definitely be into a 3-to-4-degree Celsius warming level [by the end of the century],” says Kim Cobb, a climate scientist at Georgia Tech. “If not more.” In a recent report, the United Nations警告各国必须减少排放的计划使地球步入正轨，到2100年的摄氏2.7摄氏度超过2.7摄氏度，报告强调这将是灾难性的 -和这是只有国家真正成功满足这些承诺的情况。这些数字似乎似乎是抽象的，但是以下是它们如何转化为影响。
一个三级摄氏摄氏度世界
想象一下3度变暖后的星球，以澳大利亚的榜样为例，灾难性的野火受到持续干旱和热量的燃烧，燃烧了比佛罗里达州大于佛罗里达州和2020年初大的地区 - 在烟雾中散布城市，杀人或杀害或杀害或取代30亿只动物。气候变化已经增加了该国极端火灾风险天数的数量。如果全球温度加热3度，那么在当前路径下是合理的，那么极端火灾风险天数的数量可能会翻倍甚至四倍。
最近报告详细说明该国可能会改变的其他方式。在3度全球变暖的情况下，沿海多达25万度的物业将风险洪水泛滥。澳大利亚还将面临更多的极端热量。在墨尔本，华氏95度的天数比11到24次，在该国北部领土的达尔文，高达95华氏度的天数可能从11升至平均265天。
热量会影响日常生活：例如，户外运动可能不得不搬进去。户外工作将变得更多dangerous。但这也会影响较大的系统。在海洋中，珊瑚礁可能会消失。热量已经杀死了大约一半的大堡礁。更热，更酸性的海洋会影响捕鱼。由于热，干旱和害虫数量的增加，种植食物将更加困难。关键作物的产量可能在5％至50％之间。
世界其他地方将面临类似的挑战，每个位置的特定问题集有所不同。在低洼的孟加拉国，随着海平面的提高，数以百万计的人可能被迫搬迁。从上海（可能被流离失所的1,750万人）到埃及的亚历山大到迈阿密，将洪水泛滥，从上海（可能有1,750万人流离失所）；在全球范围内，数亿人可能不得不搬迁。
In some tropical countries, the combined levels of heat and humidity may grow so high during heat waves that it surpasses the limit of what human bodies can survive. (In India, this type of extreme heat stressmay happen even at lower levels of climate change。) Droughts that are currently considered once-in-a-century events could happen every two to five years in much of the world, including parts of the U.S. As farms struggle with droughts, heat, and sometimes extreme rain, food prices will rise. The Amazon rainforest may not survive. Antarctic冰盖会更快地融化, pushing sea levels higher.
世界可能会更加升温，这取决于我们的行为速度和自然世界的变化方式，例如，在吸收碳中发挥了关键作用，开始发射的碳多于吸收。如果地球经过4摄氏度的变暖，生命将变得震撼。极端热量，飓风，火灾和其他影响的风险将增加。许多喂食亚洲河流的冰川将丢失。欧洲大部分地区可能成为沙漠。人们可以居住的地区（并可行地种植食物）将大大收缩。“一个[4度摄氏度]更温暖的世界很可能会生存，但它比我们目前喜欢的世界差得多，”记者盖亚·文斯（Gaia Vince）写入守护者。
一个二级摄氏世界
在全球变暖的2度下，世界将经历的影响仍然是极端的。像今年太平洋西北地区那样的热浪将比历史上的频率高14倍。过去十年一次发生的严重干旱将经常发生两到三倍。极端降雨的频率将高70％。珊瑚礁可能下降了99％。
The Arctic Ocean, once a decade, could become ice free in the summer. The number of days with a high risk of wildfire will grow. “Compound” events, like heat waves that happen at the same time as droughts, will become more frequent. Yields of key crops, such as rice and wheat, are likely to decline, especially in sub-Saharan Africa, Southeast Asia, and South America.
For years, limiting global warming to 2 degrees Celsius was considered an important goal—though the number was suggested somewhat arbitrarily in the 1970s by an economist; and the more scientists study the likely impacts, the worse it appears. At the negotiations for the Paris climate agreement, island nations at high risk from rising sea levels lobbied for countries to push for a more ambitious goal of limiting warming to 1.5 degrees Celsius. Countries eventually agreed to limit warming to “well below” 2 degrees Celsius, and to aim for 1.5 degrees.
A 1.5 degree Celsius world
将变暖限制为1.5度仍然不是“安全的”。但是它比2度要好得多。例如，数亿人可能会暴露于极端热浪。尽管如此，热量仍将是一个主要问题：至少每五年至少每五年一次暴露一次，超过十亿人可能会暴露于严重的热浪中。Coral reefs are likely to decline by 70% to 90%—better than the scenario at 2 degrees of warming, when reefs aren’t likely to survive at all, but still a major problem both for marine life and for people who rely on seafood to eat. The global annual catch from marine fisheries may drop by 1.5 million metric tons. The sea level may rise, on average, as much as 2.5 feet. Around 4% of the land area on the planet—more than a billion acres—will transform into a different type of ecosystem (forests, for example, may change into shrublands). Many animals, including pollinators that are critical for the food system, could lose more than half of their range. (But, by comparison, the number of insects losing habitat would triple at 2 degrees Celsius of warming.)
在1.5摄氏度以下保持温暖，到2050年将需要达到“净零”，这意味着大多数排放都被消除了，并且必须通过种植树木和使用新技术（如吸吮）吸吮的机器来同时从气氛中同时拉出大量二氧化碳巨型粉丝中的碳。当我们达到零净并变暖稳定时，我们可以走得更远。Cobb说：“我们认为，天空中大气二氧化碳浓度的周转与全球温度下降的开始之间并没有太大的滞后。”
And the changes that are needed to reach the goal have other benefits. Shifting away from fossil fuels will also dramatically improve air quality and save lives. Planting trees in cities, which in turn will makes neighborhoods more walkable, will simultaneously cut CO2 and make cities better places to live. Installing new solar and wind plants and retrofitting houses for climate change will create jobs. The transition is necessary to be able to avoid the worst-case scenario—and it also can help now.