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article imagePlants may run out of time to grow under ongoing climate change

By Karen Graham     Jun 11, 2015 in Environment
Ongoing climate change can alter conditions for plant growth, and in turn, impact our ecological and social systems. A new study looks at the consequences of changing variables that would limit plant growth, and the impact to ecosystems and people.
An assumption that warmer temperatures would be of benefit to plants in the northern latitudes has been challenged by scientists at the University of Hawai'i, Manoa.
A key fact often overlooked is that plants in the northern latitudes will still only be receiving limited solar radiation. This would curb the effects of additional warmer temperatures and CO2 availability. And that same warming could adversely affect plants in tropical regions, surpassing the acceptable heat tolerances and creating more life-threatening droughts.
Camilo Mora, a professor at the University of Hawai'i at Mānoa's College of Social Sciences, and the lead author of the new study, says, "Those that think climate change will benefit plants need to see the light, literally and figuratively."
He added, "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."
The scientists used satellite-derived data to study 95 percent of the ranges worldwide where plant growth occurs today. They focused on temperatures, water availability, and solar radiation (light availability). They then used climate projections under mitigating scenarios to show how variables in the environment that limit plant growth could impact ecosystems and people.
What the study found was that although warming temperatures would increase growing days at higher latitudes by about seven percent, the locations would still have limited light (solar radiation). "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, a co-author of the study.
Interestingly, the study also shows that tropical regions could lose up to 200 growing days every year. The biggest impact, in this case, would be to the human population, in an area where some of the world's poorest people live. The shortened growing days in these regions would also impact the economy, as well as plant-related goods and services.
The research conclude that the decline in plant growing days, along with unsuitable variables in temperatures, light, and water availability will be "most pronounced in tropical regions and in countries that are among the poorest and most highly dependent on plant-related goods and services" according to the study.
The study does end on a positive note, suggesting "changes in suitable plant growing days were negligible under strong and moderate mitigation scenarios, suggesting that even modest reductions in emissions could prevent such drastic changes and their associated consequences for ecosystems and people."
This study was published in the peer-reviewed Open Access journal PLOS Biology on June 10th, entitled: "Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability"
More about growing days, Plants, northern hemisphere, Solar radiation, New study
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