In Chicago, officials warned about the risk of almost instant frostbite on what could be the city’s coldest day ever. Warming centers opened around the Midwest. And schools and universities closed throughout region as rare polar winds streamed down from the Arctic.
At the same time, on the other side of the planet, wildfires raged in Australia’s record-breaking heat. Soaring air-conditioner use overloaded electrical grids and caused widespread power failures. The authorities slowed and canceled trams to save power. Labor leaders called for laws that would require businesses to close when temperatures reached hazardous levels: nearly 116 degrees Fahrenheit, as was the case last week in Adelaide, the capital of South Australia.
This is weather in the age of extremes. It comes on top of multiple extremes, all kinds, in all kinds of places.
“When something happens — whether it’s a cold snap, a wildfire, a hurricane, any of those things — we need to think beyond what we have seen in the past and assume there’s a high probability that it will be worse than anything we’ve ever seen,” said Crystal A. Kolden, an associate professor at the University of Idaho, who specializes in wildfires and who is currently working in Tasmania during one of the state’s worst fire seasons.
Consider these recent examples: Heat records were toppled from Norway to Algeria last year. In Australia, a drought has gone on so long that a child in kindergarten will hardly have seen rain in her lifetime. And California saw its most ruinous wildfires ever in 2018, triggering a bankruptcy filing this week by the state’s largest utility, Pacific Gas and Electric.
Is it climate change?
Heat and drought extremes are consistent with scientific consensus: More greenhouse gas emissions in the atmosphere bring a greater likelihood of abnormally high temperatures. Also, broadly speaking, scientists say, a hotter planet makes extreme weather more frequent and more intense.
The real-life numbers bear out the climate models. Concentrations of carbon dioxide in the atmosphere are higher than they have been in 800,000 years, and average global temperatures have risen. The last four years have been the hottest on record, according to the World Meteorological Organization,and the 20 warmest years on record have all come in the past 22 years. Ocean temperatures have broken records several straight years.
在芝加哥，官员们警告说，这可能是该市有史以来最冷的一天，有发生几乎瞬间冻伤的危险。暖化中心在中西部地区开放。由于罕见的极地风从北极吹来，整个地区的学校和大学都关闭了。
与此同时，在地球的另一边，澳大利亚创纪录的高温引发了野火。高耸入云的空调使用了超负荷的电网，导致了广泛的电力故障。为了节约电力，当局减速并取消了电车。劳工领袖呼吁，当气温达到危险水平（接近116华氏度）时，需要关闭企业的法律，正如上周在南澳大利亚首都阿德莱德的情况一样。
这是极端时期的天气。它出现在多种极端之上，各种各样，各种各样的地方。
爱达荷大学的副教授Crystal A.Kolden说：“当有什么事情发生时，不管是寒流、野火、飓风，还是其他任何事情，我们都需要超越过去的想象，并假设这种情况很有可能比我们见过的任何事情都更糟。”他目前在塔斯马尼亚州的一个火灾最严重的季节工作。
考虑一下最近的例子：去年从挪威到阿尔及利亚的热记录都被打破了。在澳大利亚，干旱持续了这么久，幼儿园的孩子在她有生之年几乎看不到下雨。加州在2018年发生了有史以来最具破坏性的野火，本周，加州最大的公用事业公司太平洋天然气和电力公司（PacificGas and Electric）提出了破产申请。
是气候变化吗？
极端的热和干旱符合科学共识：大气中的温室气体排放越多，异常高温的可能性就越大。此外，科学家们说，从广义上讲，一个更热的行星使极端天气更加频繁和强烈。
这些真实的数字显示了气候模型。大气中二氧化碳的浓度比80万年前高，全球平均气温也在上升。根据世界气象组织的数据，过去四年是有记录以来最热的四年，有记录以来最热的20年都是在过去的22年。海洋温度连续几年打破记录。
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