Plants may run out of time to grow under ongoing climate change

A key potential ‘benefit’ of global warming–namely, that plants at northern latitudes will thrive in a warmer world–is challenged by a new study released by University of Hawai’i scientists today.

The prevailing assumption ignores the fact that plants in the North will remain limited by solar radiation, curbing positive effects of warming and additional CO2 availability. In addition, that same warming could surpass plant temperature tolerances in tropical areas around the world, and further be accompanied by drought.

“Those that think climate change will benefit plants need to see the light, literally and figuratively,” says Camilo Mora, professor at the University of Hawai’i at Mānoa’s College of Social Sciences and lead author of the new study. “A narrow focus on the factors that influence plant growth has led to major underestimations of the potential impacts of climate change on plants, not only at higher latitudes but more severely in the tropics, exposing the world to dire consequences,” he adds.

The new study published in the peer-reviewed journal PLOS Biology shows that ongoing climate change will lead to overall declines in plant growing days by 2100 due to a mixture of warming, drought, and limited solar radiation.

Using satellite-derived data, the study identified the ranges of temperatures, soil moisture (water availability) and light (solar radiation) within which 95% of the world’s plant growth occurs today. The researchers then used climate projections to count the number of days in a year that will fall within these suitable climate ranges for plant growth in the future.

Although the study did find that warming trends will increase the number of days above freezing at higher latitudes by 7%, these same locations will remain limited by light, a trend that has been missed by previous studies that focused on temperature alone. “Regions at higher latitudes will likely have less frost and snow on the ground in the future, but many plants will not be able to take advantage of those warmer temperatures because there will not be enough sunlight to sustain their growth,” says Iain Caldwell, post-doctoral fellow at the Hawai’i Institute of Marine Biology and co-author of the study.

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