A grid-point analysis dates regional warming speedups from the 1980s through the 2010s

Thirty years separate the earliest wave from the latest. Take the middle of the 1980s and the middle of the 2010s and the gap is 30 years ^[17], inside a record that runs 55 years, from 1970 to 2024 ^[16][2]. Two grid cells can both be flagged as accelerating and disagree about the start date by more than half the length of the window being analyzed. Earlier work by members of the same team asked one question of the global mean: is an acceleration detectable at all ^[15].

The team fit models separately at each location in several observational surface-temperature data sets, then looked for coherent spatial and temporal patterns in where warming rates shifted ^[2]. "Fitting our models at each grid point allows us to identify regions with similar warming behavior," said co-author Rebecca Killick, a professor of statistics at Clemson University ^[7].

The detected timings are consistent with declining sulfur dioxide emissions from coal-fired power plants in China ^[9], and the authors note that localized drivers such as regional aerosol pollution reductions may play a role in some of the speedups but not all ^[8]. Beaulieu and her co-authors say pinpointing the physical mechanisms behind every regional speedup requires further study ^[10]. For a planner that gap is the difference between a speedup that will persist and one that was a one-time step, and the paper reports when and where rates changed ^[18].

The onset date matters for planning. Steady warming on its own shifts the baseline for the frequency and severity of heat waves, and an increase in the rate of warming can raise the likelihood of record-breaking events disproportionately ^[11]. Ecosystems are often more sensitive to rapid temperature shifts than to gradual ones ^[13]. The authors single out regions with large populations and low socioeconomic development as especially vulnerable to accelerated warming and the temperature extremes that come with it ^[12].

The most recent accelerations show up in Northern Hemisphere midlatitudes, southeast China and the Gulf of Mexico among them ^[3], with the eastern Mediterranean, Bolivia, the North Pacific and New Zealand also flagged ^[4]. Beaulieu, the lead author and an associate professor of ocean sciences at UC Santa Cruz ^[6], said she hopes the work, "along with an interactive public dashboard to enable the public to continue monitoring local rates of warming by clicking on a map," will help target efforts where they are most needed ^[14]. The paper is "Space-time signatures of surface warming accelerations since 1970," in Nature Communications ^[19].