Thread by @washingtonpost

How much warming can the world bear? That question is one of the fundamental issues in dispute at the U.N. climate change summit, known as #COP26.

Here’s what different levels of warming would look like, and how global temperature targets have been set. wapo.st/3H9Q5BX

A preliminary draft of the COP26 agreement “reaffirms” the Paris agreement’s goal: limiting warming to well below 2C and pursuing a target of 1.5C.

But it does not commit to meeting the 1.5C threshold.
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The difference between 1.5 and 2 degrees Celsius may seem small, but they represent vastly different levels of effort for countries seeking to limit their carbon footprints, and strikingly divergent outcomes for the planet. wapo.st/3H9Q5BX

Evidence shows that the two targets also represent different scenarios for the climate’s impact on human life.

A study found that 1 billion people could face heat stress, a potentially fatal combination of heat and humidity, if temperatures rise by 2C. wapo.st/3H9Q5BX

The IPCC found an extreme heat event that would have occurred once per decade in a climate without human influence, would happen 4.1 times a decade at 1.5C of warming and 5.6 times at 2C.

Events such as heavy precipitation or drought would also increase. wapo.st/3H9Q5BX

If temperatures are confined to an increase of 1.5C, over the next 2000 years, sea levels could rise by as much as 10 feet.

But it could be double that if temperatures grow by 2C, and potentially worse if ice sheets in Antarctica become destabilized. wapo.st/3H9Q5BX

Under the current scenario, the world would likely hit the 1.5C threshold by 2040, the IPCC estimated.

Under the worst scenario, the world will likely see a rise of 4.4C by the end of the century — with an extreme impact on life on Earth. wapo.st/3H9Q5BX