Up to 94% of World Regions Already Warmed Past 1.5°C, Study Finds
A Nature Climate Change study finds up to 94% of regions have passed 1.5°C of warming, with the Russian Arctic at 3.3°C. Here is how the estimate was made.
Up to 94% of the regions assessed in a new study have already warmed more than 1.5°C (2.7°F) since preindustrial times, according to research published in Nature Climate Change and reported by Eos, the news outlet of the American Geophysical Union. Some places have gone much further: Canada and large parts of Europe are past 2°C (3.6°F), and the Russian Arctic has warmed 3.3°C (5.9°F).
The global average, by comparison, stands at about 1.44°C (2.60°F). The study is the first to estimate warming at regional scale by filling in gaps where historical climate records are thin or missing, Eos reported.
How the researchers filled in the gaps
The authors worked with dozens of regions defined in the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). For each, they combined observations made within the region, global climate observations and simulations of past climate change. The goal was to estimate warming where long, complete records do not exist.
That problem is common. Francis Zwiers, a climate scientist at the University of Victoria and a coauthor, said adequate observations in Canada reach back only to 1948, and that the same holds in many other countries. Coauthor Xuebin Zhang, also at the University of Victoria, said that in some parts of the world records are sparse or nonexistent.
What the regional numbers show
- Up to 94% of regions have already passed 1.5°C of warming since preindustrial times.
- Canada and large portions of Europe have warmed more than 2°C.
- Some very high-latitude regions have warmed more than 2.5°C (4.5°F).
- The Russian Arctic has warmed 3.3°C.
Projected dates under a high-emissions scenario
The authors also projected when global average temperature would cross the Paris Agreement thresholds. Under the high-emissions scenario SSP5-8.5, they found 1.5°C would be reached in 2029 and 2°C in 2042. “That’s only 16 years from now,” Zwiers said at a press conference. Eos noted that the IPCC appears set to drop this scenario in its next assessment, and the paper did not include projections for other scenarios, so the dates apply only to that high-emissions pathway.
Why it matters
The Paris Agreement, signed in 2016, set 1.5°C as a warming limit. Eos reported that scientists are confident the world has likely already entered the 20-year period in which that limit will be breached, and that a September United Nations report said the world has virtually no chance of staying below it.
Zwiers said today’s global mean climate is already statistically indistinguishable from a world warmed by 1.5°C. Peter Stott, a climate scientist at the University of Exeter who was not involved in the study, wrote in a commentary in Nature Climate Change that the world is effectively already in a 1.5°C world. He added that impacts policymakers in Paris hoped to avoid are beginning to appear.
Zwiers said it is still possible to limit warming to no more than 2°C, but that this would require very rapid cuts in emissions from current levels.
What is still uncertain
The regional figures for places with poor records are estimates built from a method that combines sparse data with simulations, which is why the study gives the share of regions as “up to” 94%. Zhang called for more climate observations, saying sustained monitoring and high-quality data are needed to track regional change, understand effects on people and ecosystems, and support decisions on adaptation.
The paper is titled “All IPCC AR6 regions are close to their 1.5 °C- and 2 °C-equivalent warming limits.” Stott’s commentary is titled “Regional climate change approaches Paris limits.”
Source: Eos (AGU)
