Climate change: the message is clear

Today, Working Group 1 of the Intergovernmental Panel on Climate Change (IPCC) released its latest report on the physical basis of climate change. The group’s Co-Chair, Valérie Masson-Delmotte, has described the report as a ‘reality check’, and the central message is stark: anthropogenic climate change is progressing at an ‘unprecedented’ pace, and many of its impacts are now irreversible. The ambitious goal of the 2015 Paris Agreement- to limit global average temperature rise to 1.5 degrees C above pre-industrial levels- is fast moving out of reach. According to the report, the melting of the Arctic, sea level rise and changes to ocean chemistry are among the effects of climate change that cannot now be fully undone.

The report, whose hundreds of international expert contributors include members of PLOS Climate’s editorial board, comes at a time when the devastating impacts of rapid climate change around the world are plain to see. Right now, vast wildfires are sweeping through parts of the Mediterranean and California, just weeks after catastrophic flooding hit Western Europe and China and heatwaves caused spikes in deaths and illness in North America. Such instances form part of a worrying pattern of increasingly extreme weather events that the IPCC WG1 report ‘unequivocally’ attributes to human impacts on the climate system. In 2020, the Caribbean region suffered from a record-breaking number of tropical storms, and droughts are predicted in the 2021 dry season. In Amazonia, climatic drying is interacting with deforestation activity to stoke numerous destructive fires. Meanwhile, in Madagascar over a million people are currently without reliable access to food in a fourth consecutive year of intense drought.

Whilst parts of the report make for bleak reading, it also places emphasis on steps that can- and must- be taken to minimise the extent of future climate change. Above all, deep reductions in greenhouse gas emissions are desperately needed, including at least global net zero CO₂ emissions. COP26, the global climate summit scheduled for November this year, is seen by many as a last-ditch opportunity for concerted political action in the face of overwhelming evidence for the damage that has already been done and the dangerous future that lies ahead. The President of COP26 has said that the IPCC WG1 report shows that ‘the lights are flashing red on the climate dashboard’ and that ‘ambitious emission reduction targets that lead us to net zero by 2050’ must be agreed at the summit in Glasgow.

The process of collecting, synthesising and communicating a huge corpus of scientific evidence is a monumental undertaking, and all involved in this report must be congratulated for their contributions. Through their collective efforts and expertise, and drawing on the crucial work of the wider scientific community, the report’s authors have distilled a sobering and compelling message that must be heeded and acted upon with urgency. The IPCC’s Working Groups 2 (impacts, adaptation and vulnerabilities) and 3 (mitigation of climate change) will report in 2022, and their findings will be combined with WG1’s to form the IPCC’s overarching Sixth Assessment Report (AR6).

Jamie Males, Executive Editor, PLOS Climate