The assessment comes as record-breaking heat waves, devasting floods and drought struck across three continents in recent weeks. “This report has been prepared in exceptional circumstances, and this is an unprecedented IPCC approval session,” Intergovernmental Panel on Climate Change (IPCC) Chair, Hoesung Lee, told the opening session of the meeting.

The report, Climate Change 2021: the Physical Science Basis, by IPCC Working Group I brings together the latest advances in climate science and multiple lines of evidence to provide an up-to-date physical understanding of the climate system and climate change.

‘Climate crossroads’

“Assessments and special reports have been foundational to our understanding of climate change, the severe and growing risks it poses throughout the world and the urgent need for action to address it,” said UN Climate Change Executive Secretary Patricia Espinosa, on Monday.

But she warned that the world is at a “climate crossroads” and decisions taken this year would determine whether it will be possible to limit global warming to 1.5°C above the pre-industrial era by the end of the century.

3 degrees looming

“The world is currently on the opposite track, heading for a 3°C rise,” she said. “We need to change course urgently.”

Following the recent deadly flooding in several western European countries, the World Meteorological Organization (WMO) called for all nations to do more to hold back climate change-induced disasters.

“Climate change is already very visible. We don’t have to tell people that it exists,” WMO Secretary-General Petteri Taalas told the opening session. “We are seeing more extreme events. Heatwaves, drought and the flooding events in Europe and China,” he said. 

“Massive heating” in the Arctic is affecting the atmospheric dynamics in the northern hemisphere, as evidenced by stagnant weather systems and changes in the behaviour of the jet stream, added the WMO chief.

‘Science has spoken’

Some 234 authors have contributed to the assessment, which will provide the latest detailed assessment on past warming and future warming projections; show how and why the climate has changed and include an improved understanding of human influence on the climate.

There will also be a greater focus on regional information that can be used for climate risk assessments.

Time for action

“We have been telling the world that science has spoken and it’s now up to the policymakers for action”, said IPCC Chair Hoesung Lee.

The meeting is being held remotely from 26 July to 6 August, with the aim of ensuring that the summary for policymakers is accurate, well-balanced and presents the scientific findings clearly.

Subject to the decisions of the panel, the report will be released on 9 August, just weeks ahead of the UN General Assembly opening, a G20 summit, and the 197-nation COP26 climate summit in Glasgow. The document is the first part of the Sixth Assessment Report, which will be will be finalised in 2022​​.