Researchers at Lawrence Berkeley National Laboratory, part of the U.S. Department of Energy, note that climate change is reshaping snowfall and rain patterns in the northern hemisphere’s mountain regions. These liquid water events carry a spectrum of hazards, including floods, landslides, and soil erosion, as discussed in Nature.
Interpreting the study, lead author Mohammed Ombadi highlights that about a quarter of the world’s population lives in or near mountainous areas. This means a substantial portion of communities will face increased risk as precipitation patterns shift. Scientists have long anticipated that extreme weather events will bring more rain during intense episodes, which can last from a few hours to a day, but this study is the first to directly examine whether these events manifest as rain or snow.
The research shows that in mountainous zones, the fraction of precipitation falling as snow is declining while rain is rising, making these regions more exposed to the dangers of heavy rainfall. The researchers quantify the trend: on average, higher elevations may see about 15 percent more rain for every one degree Celsius rise in global temperature.
Ombadi emphasizes that the shift is not a distant concern. The data reveal a similar tempo from 1950 to 2019, with mountain peaks already changing and rainfall amounts increasing by roughly 15 percent in some areas. The trajectory will continue to evolve as temperatures rise.
Mountains in the northern hemisphere are increasingly becoming sources of excessive precipitation due to warming. The Pacific mountain systems of North America, including the Cascades and Sierra Nevada, along with Canadian to southern California ranges, the Himalayas, and high-latitude regions, show the greatest sensitivity to extreme precipitation. Researchers are still exploring why these ranges are more vulnerable than others such as the Rockies or the Alps.
Ombadi explains that the Pacific North American ridges appear particularly prone to heavy precipitation because much of the snowfall there occurs near the freezing point. Even a small uptick in air temperature can convert snow into rain, whereas some other ranges can continue receiving snowfall at temperatures well below freezing.
The aim is for climatologists to incorporate the distinction between snowfall and precipitation into climate models, while civil engineers and planners use the data to bolster preparation for heavy rain events in mountainous regions.
There is a clear imperative to factor these outcomes into the design and construction of infrastructure in these areas, ensuring resilience against intensified rainfall. Countries likewise pursue targets set by international climate frameworks to limit warming close to two degrees Celsius above pre-industrial levels.
One finding indicates a linear relationship between warming and excess precipitation: for example, a one-degree rise in temperature correlates with about 15 percent more precipitation, while a three-degree rise could lead to around 45 percent more. The study’s authors stress that progress in technologies to cut greenhouse gas emissions is already underway and that investing in clean solutions, along with planning for warming-driven changes, is essential.
These insights underscore the urgency of proactive adaptation alongside mitigation as the climate continues to warm.
Note: This article cites published research and related data to support its analysis.