A new study finds that tropical areas often thought to be safe from the effects of climate change are actually experiencing significant changes in rainfall and extreme temperature events.
Researchers studied climate events at the La Selva research station in Costa Rica and the El Verde field station in Puerto Rico. They found that, while average temperatures were not changing much over time, the two locations did experience significantly more days of extreme heat in 2024 compared to long-term data stretching back to 1992.
"In La Selva prior to 2024, you had an average of eight hot days - days where the temperature exceeded the 95th percentile of temperatures at that site - per year," said Alonso Ramirez, lead author of the study and a professor in the Department of Applied Ecology at North Carolina State University. "Now that number is up to 30. These spikes in temperature are becoming more severe and more common."
Notably, the two locations also experienced contrasting precipitation patterns, despite being relatively close to each other. La Selva experienced more heavy-rain events and fewer zero-rain days, while El Verde experienced more dry days. At La Selva, instances where rainfall exceeded the 99th percentile rose from around one event per year between 1983 and 1985 to six per year in 2024. El Verde showed no significant increase in heavy-precipitation events, but saw an increase in dry extremes from 152 to 170 days per year.
"That was surprising, that one is getting wetter and one is getting drier," said Marcelo Ardon, co-author of the paper and a professor in the Department of Forestry and Environmental Resources and the Center for Geospatial Analytics at NC State. "Given how close they are to each other, we expected to find similar trends across the two sites. This shows how climate change is happening right now, and we can demonstrate that with data that doesn't stretch that far back."
These findings demonstrate how climate change is affecting even areas typically thought of as having stable climates.
"A lot of people tend to think of the tropics as being stable and unchanging, especially in protected areas like the ones we're studying," said Ramirez. "Conventional wisdom would say that these places should not show much of a change from anthropogenic impacts. Instead, these two sites that are hotspots for research are showing clear changes in climate and in the environment, which then affects the functioning of the ecosystem."
The paper, "Shifting climate in Caribbean tropical forests: Long-term trends at La Selva (Costa Rica) and El Verde (Puerto Rico)" is published in PLOS Climate. Co-authors include Pavel Garcia of Universidad de San Carlos de Guatemala, Nicholas S. Marzolf of The Jones Center at Ichauway and David Genereux of NC State University.
-pitchford-
