The World Will Blaze Past Its 1.5 Degree Climate Goal. Now What?

This story is part Choose Eartha series that chronicles the impact of climate change and explores what is being done to address the problem.

As the United Nations Climate Conference COP27 launched this week in Egypt, UN Secretary General António Guterres proclaimed that the world is on a “highway to climate hell with the foot still on the accelerator”. To prevent the temperature from rising 1.5 degrees Celsius above pre-industrial levels by 2100, we need to curb greenhouse gas emissions. Hard.

In fact, we basically had to completely stop the runaway truck immediately.

The climate commitments made by nations at last year’s COP26 conference seemed like a positive step in the right direction, but there is no doubt that the average temperature increase on Earth will exceed the 1 mark, 5 degree over the next few decades – an “overshoot” scenario. — before potentially come down again at the end of the century. Can we limit this excess? And how could we do that?

A study, published Thursday in the scientific journal Nature Climate Change, tried to answer these questions by modeling 27 different emission reduction pathways of varying ambition. He came to an unsurprising conclusion: countries must act by increasing the ambition of their climate commitments. And they must act now.

“If countries can increase their ambition for 2030 at the COP this year, it could significantly reduce both the duration and the magnitude of the overshoot,” said Gokul Iyer, scientist at the Joint Global Change Research Institute and first author of the study.

The 1.5 degree rise has long been seen as a critical milestone in the fight against climate change. Since the signing of the Paris Agreement at COP21 seven years ago, scientists have rigorously studied how this level of warming above pre-industrial temperatures would affect the Earth. The models and simulations they have built show that we are likely to see more extreme weather events, in addition to melting ice, rising sea levels that threaten many Pacific nations with low altitude and a significant loss of biodiversity once temperatures exceed a 1.5 degree increase. .

At COP26 in November 2021, countries presented more ambitious emissions reduction pledges (known as NDCs) in an effort to curb global warming. However, research conducted last year by Iyer, Haewon McJeon and their colleagues showed that even if If these commitments are met, it is likely that temperatures will rise by around 1.8 degrees Celsius by the end of the century.

Under the Glasgow Climate Pact, signed at COP26, nations had to come up with ever more ambitious commitments to decarbonization. The new study comes at a critical time, when these discussions are taking place in giant conference halls in Egypt for COP27.

McJeon, a research fellow at the Joint Global Change Research Institute and co-author of the study, hopes the study will help highlight the “gap” between the current pledges and the primary goal of 1.5 degrees. It examines how countries can increase the ambition of pledges through three particular mechanisms: increasing short-term actions through 2030, accelerating decarbonization after 2030, and advancing net-zero pledges.

“The most important thing we find in the options menu to increase ambition is to increase ambition for 2030,” McJeon said.

Without increasing short-term ambitions, we envision a period of overshoot that could last decades and continue until 2100. However, if countries double their pledges, as envisioned in the Glasgow Climate Pact last year, then there is an opportunity to reduce the overshoot time to about half a century. This could have a significant impact on human health and the environment.

“Every tenth of a degree counts. Every year of overshoot counts,” McJeon said.

McJeon noted that there has been incremental progress over the past five years – it’s not satisfactory or enough to limit warming to 1.5 degrees – but it’s more advanced than where he seemed to be heading. about five years ago.

Although exceeding 1.5 is bad (and this is bad), 2 degrees of warming is even worse. This study goes further to show that the 1.5 degree lens is pretty much dead, but the situation is not hopeless. Today more than ever, there is a need to reduce greenhouse gas emissions by setting more ambitious targets. But, notes Iyer, ambition alone is not enough. We also need action.

As dignitaries and policy makers meet in Egypt, McJeon has a pretty simple message.

“I hope they will read our newspaper,” he said.

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