“We decided to incorporate the known physiological effects of leaf thickening into climate models to find out what effect, if any, this would have on a global scale.”Ī 2009 paper by researchers in Europe and Australia collected and catalogued data from years of experiments on how plant leaves change in response to different environmental conditions. ![]() “Plant biologists have gathered large amounts of data about the leaf-thickening response to high carbon dioxide levels, including atmospheric carbon dioxide levels that we will see later this century,” said Kovenock. Plants are crucial modulators of their environment - without them, Earth’s atmosphere wouldn’t contain the oxygen that we breathe - and Kovenock and Swann believed that this critical and predictable leaf-thickening response was an ideal starting point to try to understand how widespread changes to plant physiology will affect Earth’s climate. Leaves can thicken by as much as a third, which changes the ratio of surface area to mass in the leaf and alters plant activities like photosynthesis, gas exchange, evaporative cooling and sugar storage. But the response has been documented across many different types of plant species, such as woody trees staple crops like wheat, rice and potatoes and other plants that undergo C 3 carbon fixation, the form of photosynthesis that accounts for about 95 percent of photosynthetic activity on Earth.īoreal forest scene near Fairbanks, Alaska. Scientists don’t know why plants thicken their leaves when carbon dioxide levels rise in the atmosphere. “If this single trait - leaf thickness - in high carbon dioxide levels has such a significant impact on the course of future climate change, we believe that global climate models should take other aspects of plant physiology and plant behavior into account when trying to forecast what the climate will look like later this century,” said Kovenock, who is lead author on the paper. ![]() In addition to a weakening plant carbon sink, the simulations run by Swann and Marlies Kovenock, a UW doctoral student in biology, indicated that global temperatures could rise an extra 0.3 to 1.4 degrees Celsius beyond what has already been projected to occur by scientists studying climate change. Scene near the Wayqecha Cloud Forest Biological Station in Peru’s Manú National Park. ![]() “But until now, no one had tried to quantify how this type of response to climate change will alter the impact that plants have on our planet.” “Plants are flexible and respond to different environmental conditions,” said senior author Abigail Swann, a UW assistant professor of atmospheric sciences and biology. Those levels are similar to the amount of carbon released into the atmosphere each year due to human-generated fossil fuel emissions - 8 petagrams, or 8.8 billion tons. 1 by the journal Global Biogeochemical Cycles, the researchers report that, when they incorporated this information into global climate models under the high atmospheric carbon dioxide levels expected later this century, the global “ carbon sink” contributed by plants was less productive - leaving about 5.8 extra petagrams, or 6.39 billion tons, of carbon in the atmosphere per year. Two University of Washington scientists have discovered that plants with thicker leaves may exacerbate the effects of climate change because they would be less efficient in sequestering atmospheric carbon, a fact that climate change models to date have not taken into account. Plant scientists have observed that when levels of carbon dioxide in the atmosphere rise, most plants do something unusual: They thicken their leaves.Īnd since human activity is raising atmospheric carbon dioxide levels, thick-leafed plants appear to be in our future.īut the consequences of this physiological response go far beyond heftier leaves on many plants. Tropical forest canopy in Caxiuanã, Brazil.
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