Most U.S. states are warming but not in the way you think

Although climate change is a global problem, its impacts are not evenly distributed. Local conditions shape how warming is experienced, which means policies and adaptation strategies must be tailored to specific areas. Compared to topics like public health or economic inequality, these regional climate differences have not been studied in as much detail.

To address this gap, the researchers developed a framework to examine temperature changes across the contiguous 48 United States, allowing for a more precise comparison of how warming unfolds in different locations.

Data Reveals Hidden Warming Trends

The study analyzed average temperatures from 1950 to 2021, along with more than 26,000 daily temperature readings per state. This approach captured not just average changes but the full range of temperatures experienced locally.

The findings show a more complex picture than simple averages suggest. Only 27 states (55%) recorded a rise in average temperatures. However, 41 states (84%) showed increases in at least part of their temperature range. In some places, this means hotter peak temperatures, while in others it reflects milder lows. For instance, states along the West Coast are seeing higher annual temperature extremes, while many northern states are experiencing warmer minimum temperatures.

Impacts on Health, Agriculture, and Policy

These differences could have significant consequences. Shifts in temperature extremes can affect crop growth, strain public health systems, and influence how communities perceive climate risks. All of these factors play an important role in shaping local climate policies and responses.

The researchers note that their method could also be used to study other climate-related changes, including shifts in precipitation patterns and rising sea levels.

Looking Beyond Averages

The authors summarize: "Looking beyond average temperatures, we show that most U.S. states are warming in specific parts of the temperature distribution, even when average warming is not statistically significant. This reveals strong regional inequalities in how climate change is experienced across the United States."

Funding: Gobierno de Aragón and European Regional Development Fund (ERDF, EU), grant LMP71-18 -- received by MDG. Agencia Española de Investigación (MCIN/AEI/10.13039/501100011033) and ERDF, grants PID2020-114646RB-C44 (MDG), PID2023-147593NB-I00 (JG), PID2023-150095NB-C44 (MDG), RED2022-134122-T (LG, JG). MCIN/AEI and European Union NextGenerationEU/PRTR, grant TED2021-129784B-I00 -- received by MDG and JG. MCIN/AEI, grant CEX2021-001181 (María de Maeztu) -- received by JG. Comunidad de Madrid, grants EPUC3M11 and V PRICIT -- received by JG. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.