2C or 1.5C? How global climate targets are set and what they mean

How much warming can the world bear?

That question is one of the fundamental issues in dispute at the ongoing U.N. climate change summit, known as COP26, in Glasgow, Scotland.

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

Six years ago, when countries came together in Paris for the COP21 summit, at which the Paris climate accord was shaped, they committed to limit the global average temperature rise to well below 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels. However, while the 2015 agreement set 2C as the minimum, it included language that suggested countries should push for a more ambitious goal: 1.5C.

A preliminary draft of the COP26 agreement released Wednesday “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.

The difference between the two targets 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.

Some experts doubt that 1.5C remains achievable. Limiting warming to 1.5C “will be very difficult,” Microsoft founder and philanthropist Bill Gates told U.K. lawmaker Jeremy Hunt in a conversation hosted by the think tank Policy Exchange last week.

Evidence shows that the two targets also represent different scenarios for the climate’s impact on human life. A study released Tuesday by the U.K. Met Office, Britain’s national weather service, found that 1 billion people could face heat stress, a potentially fatal combination of heat and humidity, if temperatures rise by 2C.

“The higher the level of warming, the more severe and widespread the risks to people’s lives, but it is still possible to avoid these higher risks if we act now,” said Richard Betts, one of the leaders of the project.

Tuvalu's foreign minister gave a speech to COP26 on Nov. 8, standing in the ocean to show how his Pacific island nation is on the front line of climate change. (Video: Reuters)

More on climate change

Understanding our climate: Global warming is a real phenomenon, and weather disasters are undeniably linked to it. As temperatures rise, heat waves are more often sweeping the globe — and parts of the world are becoming too hot to survive.

What can be done? The Post is tracking a variety of climate solutions, as well as the Biden administration’s actions on environmental issues. It can feel overwhelming facing the impacts of climate change, but there are ways to cope with climate anxiety.

Inventive solutions: Some people have built off-the-grid homes from trash to stand up to a changing climate. As seas rise, others are exploring how to harness marine energy.

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