According to recent research, severe droughts are becoming common in the American Southwest and Mexico, while the Northeast is experiencing more intense wet years. The study suggests that these seasonal weather patterns will likely become more extreme in the future.
The central United States is projected to see more significant fluctuations between wet periods, referred to as pluvials, and drier summers throughout this century, according to the study’s predictions.
Researchers from The Ohio State University based their findings on contemporary precipitation data, historical tree ring analysis, and climate models covering the years 850 to 2100. They conclude that climate change has resulted in precipitation patterns across North America experiencing extremes that were not present before industrialization began in the mid-1800s.
James Stagge, an assistant professor of civil, environmental, and geodetic engineering at Ohio State and senior author of the paper, noted, “It’s essentially a contrast between the Southwest and the Northeast across most seasons.” He explained that the Southwest and Mexico are seeing drier conditions in nearly every season, while the Northeast, including Ohio, is trending towards wetter conditions, particularly in winter and early spring.
The interplay of dry conditions and wet pluvials in much of the U.S. midsection will not follow a predictable pattern.
Stagge elaborated, “For example, we might be experiencing severe drought this year, but in five years we could see an exceptionally wet pluvial. This variability raises concerns as it alters how we need to manage water resources to adapt to these extremes. Preparing for this is quite challenging.”
“This is a reflection of a broader trend that will continue to worsen in the future,” he added.
Kyungmin Sung, a former graduate student at Ohio State and now a research fellow at the Korea Environment Institute, is the lead author of this research paper, which was published on September 6, 2024, in Geophysical Research Letters.
Unlike studies that focus on how climate change affects specific extreme weather events, this research documents long-term trends of droughts and pluvials across North America, both before and after industrialization.
The team compared the climate patterns of the past 20 years with those from the pre-industrial era and projected the trends in low and high precipitation until 2100.
“We can say: ‘This is the extent of change we’ve noticed in the last century due to rising greenhouse gas levels compared to the previous 700 years,'” Sung explained. “The current and projected changes are significantly greater in many regions than any previous natural climate variation.”
To support their findings, researchers compiled data from five sources: two modern precipitation observation sets, historical tree ring reconstructions, and two climate models that cover the same historical period and continue to predict future extremes influenced by increasing greenhouse gases.
Stagge emphasized the strength of their findings, stating, “Combining diverse data types enhances credibility, as they can fill in each other’s gaps. We deem a trend significant only if it appears consistently across multiple datasets, thereby bolstering our confidence.”
The maps illustrating changing climate patterns indicate that the methodology successfully produced clear spatial transitions and defined boundaries, reinforcing the idea that the observed changes are genuine.
While the ongoing drying trend in the West is well-documented, the team was taken aback by the extent of precipitation increases, especially in the Northeast, and the stark variability predicted for the central United States between droughts and pluvials.
These alternating water availability patterns may impact various sectors, including agriculture, construction, and urban planning, while also challenging efforts to maintain optimal household water reservoirs.
“Planners, government agencies, and engineers aim to prepare for a potentially changing climate but often lack the detailed information needed to understand forthcoming conditions,” Stagge explained. “This research serves as a warning. In the Southwest, expect less water availability, and in the Midwest, anticipate larger fluctuations between droughts and pluvials.”
“While we hope to mitigate ongoing climate change, it takes considerable time to effect change,” he concluded. “In the meantime, we should plan for the future to minimize impacts on people, the economy, and the environment.”
This research was funded by the National Science Foundation, the Byrd Polar and Climate Research Center at Ohio State, and the Ohio Supercomputer Center. Gil Bohrer from Ohio State also contributed as a co-author of the paper.
