Climatologists find it difficult to find the right words for very bad news

In South Korea, in Incheon, this week, representatives from more than 130 countries and some 50 scientists gathered in a major conference center incorporating all the lines of a report of utmost importance: What are the chances of the planet moderately limiting climate change, controllable level?

When they can not get along, they form "contact groups" outside the lobby to try to reach an agreement and move the process forward. They are trying to reach a consensus on what this would mean and what should be done to limit global warming to only 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, while a Celsius degree is already produced and that greenhouse gas emissions remain at an all time high. highs.

"This is the largest peer review exercise," said Jonathan Lynn, Communications Officer, United Nations Intergovernmental Panel on Climate Change. "It involves hundreds or even thousands of people watching it."

The IPCC, the world's foremost scientific body in the fight against climate change, was awarded the Nobel Peace Prize ten years ago and has been entrusted with what might be its most difficult task.

This must not only tell governments what we know about climate change, but also how much they have brought us to the brink. And, implicitly, how these governments fail in achieving their goals for the planet, as defined in the 2015 Paris climate agreement.

The most ambitious and ambitious goal of this agreement is 1.5 degrees. It originated at the request of small island states and other highly vulnerable countries. But it is increasingly viewed by all as a critical safety net, as serious impacts of climate change have been felt over the past five years, raising concerns about the impact of further warming.

"Half a degree does not seem to help you put it in the right context," said Durwood Zaelke, president of the Institute for Governance and Sustainable Development. "It's 50% more than what we have now."

The idea of ​​letting the warming approach 2 degrees Celsius seems more and more disastrous in this context.

Parts of the planet, such as the Arctic, have already warmed by more than 1.5 degrees and are experiencing alarming changes. Antarctica and Greenland, containing several feet of sea level rise, flicker. Significant deaths have affected coral reefs around the world, suggesting that an irreplaceable planetary feature may soon be lost.

It is universally recognized that the promises made in Paris would lead to a warming well beyond 1.5 degrees – closer to 2.5 or 3 degrees Celsius or more. And that was before the United States, the second largest transmitter in the world, decided to try to backtrack.

"The commitments made by countries during the Paris Climate Agreement do not bring us closer to what we need to do," said Drew Shindell, climate expert at Duke University and one of the authors of the IPCC report. "They have not really engaged in actions to reduce their emissions to match what they claim to aim for."

The new 1.5 C report will fuel a process called "Talanoa Dialogue", in which the parties to the Paris Agreement begin to look at the big divide between what they claim to achieve and what they say. they are doing. The dialogue will take place in December at an annual United Nations climate meeting in Katowice, Poland.

But we do not know what concrete commitments can be made.

The challenge is what scientists call the "carbon footprint": as carbon dioxide lives in the atmosphere for a long time, there is little emission that can be emitted before it becomes impossible to avoid a temperature. given, such as 1.5 degrees Celsius. And as the world emits about 41 billion tons of carbon dioxide a year, if the remaining budget is 410 billion tons (for example), scientists can say that we are 10 years old until the budget has elapsed and 1,5 C is blocked.

Unless emissions begin to decline – giving more time. This is why the scenarios of maintaining warming at 1.5 ° C require rapid and profound changes in the way we get energy.

The window can now be as narrow as about 15 years of current programming, but as we do not know for sure, it really depends on the margin of error we are willing to concede.

And if we can not reduce other gases, such as methane, or if Arctic permafrost begins to emit large amounts of additional gas, the budget shrinks further.

"It would be a huge challenge to stay below a threshold of 1.5 degrees Celsius," says Shindell. "It would be a really huge elevator."

So huge, he said, that would require a monumental shift towards decarbonization. By 2030, in just a decade, global emissions are expected to fall by about 40%. By mid-century, companies would no longer need to issue net issues. What can it look like? This includes things such as the lack of gas-powered vehicles, the phasing out of coal-fired power plants and biofuel-powered aircraft, he said.

"It's a radical change," he said. "These are huge, huge changes … that would really be a rate and magnitude of unprecedented change."

And this is only the essential: 1.5 degrees is still possible, but only if the world undergoes a stunning transformation.

A first version (published and published by the Climate Home News website) suggests that future scenarios of a 1.5 C warming limit would require massive deployment of technologies to remove carbon dioxide from the environment. air and bury it underground. Such technologies do not exist at a level close to that which would be required.

"There are now a very small number of trails [to 1.5C] it does not involve the elimination of carbon, "said Jim Skea, chairman of IPCC Working Group III and professor at Imperial College London.

It is unclear how scientists can best convey this message to governments around the world – nor how ready they are to hear it.

A draft leaked report indicated that there was a "very high risk" that the world would warm up by more than 1.5 degrees. But a subsequent project, also leaked in Climate Home News, seemed to back down, saying that "there is no simple answer to the question of whether it is possible to limit global warming". at 1.5 ° C. . the feasibility has several dimensions that must be considered simultaneously and systematically ".

None of these languages ​​are final. This is the subject of this week in Incheon – to prepare the report for an official publication Monday -.

"I think a lot of people would be happy if we went further than us," IPCC's Lynn said Wednesday morning in Incheon. "But in all the approval sessions I've seen, I've seen five now, that has always been the case, and it ends up happening there."