Plant scientists have observed that when levels of carbon dioxide in the atmosphere rise, most plants do something unusual:They thicken their leaves.
And since human activity is raising atmospheric carbon dioxide levels, thick-leafed plants appear to be in our future.
But the consequences of this physiological response go far beyond heftier leaves on many plants. 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.
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 million tons, of carbon in the atmosphere per year. 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 million tons.
"Plants are flexible and respond to different environmental conditions,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."
High CO2 levels cause plants to thicken their leaves, could worsen climate change effects
"If this single trait—leaf thickness—in high carbon dioxide levels has such a significant impact on the course of future climate change, so 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.
Scientists don't know why plants thicken their leaves when carbon dioxide levels rise in the atmosphere. But the response has been documented across many different types of plant species, such as woody trees; field crops like wheat, rice and potatoes; and other plants that undergo C3 carbon fixation, the form of photosynthesis that accounts for about 95 percent of photosynthetic activity on Earth.
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. Plants are crucial modulators of their environment—without them, Earth's atmosphere wouldn't contain the oxygen that we breathe 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.