A major report finding the window is fast closing – but not closed – to limiting global warming to 1.5°C, was released Sunday by the Intergovernmental Panel on Climate Change.
A key message of the report was the stark difference between 1.5°C of warming, and 2°C or more (the planet has already warmed about 1°C). The difference would be measured largely in human suffering, especially by poor and vulnerable populations. Past 1.5ºC, the report found the planet increasingly besieged by extreme weather events, food shortages, flooding and wildfires.
“Every extra bit of warming matters, especially since warming of 1.5ºC or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems,” said Hans-Otto Pörtner, Co-Chair of IPCC Working Group II.
Holding below warming of 1.5°C would also “give people and ecosystems more room to adapt and remain below relevant risk thresholds,” added Pörtner.
At 2°C or more, sea levels would rise another 10cm (exposing 10 million more people to flooding risk), the Arctic Ocean would be free of summer ice on average once a decade, and coral reefs worldwide would be gone.
“The good news is that some of the kinds of actions that would be needed to limit global warming to 1.5ºC are already underway around the world, but they would need to accelerate,” said Valerie Masson-Delmotte, Co-Chair of Working Group I.
The report found “rapid and far reaching” transitions would be needed across sectors to make 1.5°C work, requiring carbon dioxide emissions to drop 45% from 2010 levels by 2030, and falling to net zero emissions by around 2050.
Failing to keep below 1.5°C would also increase reliance on negative emission technologies unproven at scale and with “significant risks for sustainable development.”
“The decisions we make today are critical in ensuring a safe and sustainable world for everyone both now and in the future .… The next few years are probably the most important in our history,” said Debra Roberts, Co-Chair of IPCC Working Group II.
The IPCC is regarded as the leading world body for assessing climate change science and risk. The report cited over 6000 scientific references and involved thousands of experts.