The United Nations will release on Monday its most comprehensive assessment yet of global warming. The report includes estimates on how greenhouse gas emissions will drive extreme weather in near future. Compiled by 200 scientists (all experts in their fields), the report is also expected to emphasize that humans are responsible for climate change and are severely altering the way the planet works.

The report, which covers the latest advances in climate science, comes at a key moment: three months before the UN climate summit COP26 in the United Kingdom, where world leaders are expected to make new commitments to curb emissions. Climate experts hope the new findings will accelerate climate action to meet the targets of the Paris Agreement. 

In 2015, countries agreed to limit the temperature increase to 2ºC above pre-industrial times, ideally aiming at 1.5ºC. But the global average temperature has already increased 1ºC and is on track to reach at least 3ºC by the end of the century — that’s if countries keep their climate promises (which they are currently not).

Elaborated by the Intergovernmental Panel on Climate Change (IPCC), a global group of leading climate experts, the report takes place as extreme weather events shake up most of the world. North America and several parts of Europe, for example, have seen record-breaking temperatures, leading to forest fires, deaths, and hospitalizations. 

So what can we expect from the report?

“I think it’s going to be a wake-up call, there’s no doubt about that,” Richard Black, an honorary research fellow at the Grantham Institute at Imperial College London, told BBC News. “But then again, so are some of the real-world events that we’re seeing around us at the moment.”

Why the IPCC is so important

The IPCC was formed in 1988 to provide politicians with assessments every six or seven years on the science, impacts and potential options for dealing with climate change. Its reports have become more strongly worded over the years, as evidence has mounted. The IPCC doesn’t do its own research but assesses already published academic work.

In 2013, the climate experts stated in a report that humans were the “dominant cause” of global working since the 1950s — a strong assessment that helped to set the scene for the Paris climate agreement — the first realistic climate agreement signed by virtually all countries.

For its studies, the IPCC divides the work in three areas:  physical science, the one now being published, impacts, and mitigation – both to come out next year. As well as its six- or seven-year assessments, the IPCC has also published special studies looking at specific questions. In 2018, for example, it released a report on the importance of keeping global temperature rise under 1.5ºC. The findings triggered a massive reaction from young people, taking the streets to demand a political response.

“The 1.5C report was really kind of instrumental for young people to use that science to marshal their efforts towards action,” Ko Barrett, a vice chair of the IPCC, told BBC News. “I think maybe the report surprised us all, that the report had such an impact in getting people to think, wow, this is not some big future problem. This is like right now.”

Expectations for the report

For the new report, more than 200 climate researchers from around the world have been working together in groups over the past four years to review existing peer-reviewed literature. The final draft was subject to discussions and comments (over 75,000) from fellow researchers and from governments, leading to many rewrites. 

“The scientists come in with a proposal document that line by line gets challenged by the representative of the United Nations there, and the scientists defend their lines,” said Prof Corinne Le Quéré, from the University of East Anglia, told BBC News. “Nothing gets written that is not scientifically correct. So, scientists have the right to just say this is wrong.”

The report will likely have a strong focus on mankind’s role in causing the climate crisis. In the last report in 2013, the authors said that global warming since the 1950s was “extremely likely” because of human activities, such as fossil fuels extraction. This wording is likely to be further strengthened, despite objections from a few countries. 

The IPCC report will also likely warn that we are dangerously close to breaching the Paris Goals of limiting average global temperature rise to 1.5ºC already — although that 1.5C is still within reach. Back in May, leaders of the G7 reaffirmed their commitment to the 1.5º target, while a similar sign is expected from the G20 leaders when they meet in October. Whether or not those commitments will be respected though, is a different thing.

There will also be a chapter on weather and extreme events in a changing climate. Governments asked the IPCC to look at low probability events that can be very damaging, such as the storms, floods, and droughts seen around the world recently. It will be the first time for the IPCC to provide explicit information on extreme climate events. 

With just a few months left before the COP26 climate conference, the stakes are perhaps higher than at any time in recent history. All of us are more familiarized with the issue of climate change than ever before, given the scale of the weather-related disasters, and the new IPCC report will provide new insight on the need to scale up climate action.