Tiny pores in plant leaves, poorly understood until now, are integral to creating accurate climate change forecasts.
The tiny pores on leaves influence vast areas of Earth's climate.
Current climate models only approximate how plants influence weather and climate.
New research is finally getting to just how those pores, called stomata, work.
New research on how microscopic leaf pores respond to sunlight reveals some of the first universal relationships between plants and climate.
Understanding these relationships could vastly improve climate and weather models so they properly represent atmospheric changes over forests, grasslands and other areas where plants dominate.
"If you took a (climate) model and wiped out all the plants in the world, it would be a lot hotter and drier," explained Joseph Berry of Stanford University and Carnegie Science.
That's because plants transpire water via pores called stomata in response to such things as how much sunlight is shining on them, how much photosynthesis is under way and how much carbon dioxide is in the air.
For years now, climate models have included information about plants based on measurements collected by Berry and others from actual plants transpiring.
That data has been used, for instance, to argue that higher CO2 levels are causing plants to close down stomata, reduce transpiration of water, and therefore increase stream flows as plants take up less water from the ground.
The problem is, that early plant data just covers of a few species of plants and is not based on any deeper understanding of how plants -- or more specifically, their stomata -- respond to changes in light, heat and CO2.
"I felt really uneasy and wanted more information on stomatal behavior, rather than just empirical plant data," Berry told Discovery News.
So he and his colleagues conducted meticulous laboratory research on how stomata, and therefore transpiration and the water balance inside leaves, respond to light absorbed by leaves. They discovered that stomata are not just simple pores in leaves, but also solar energy meters that control the rates of transpiration in leaves.
"This observation is at odds with current concepts of how stomata sense and control transpiration," report Berry, Roland Pieruschka and Gregor Huber in a paper in the July 12 issue of Proceedings of the National Academy of Science.
It's long been thought that photosynthesis is driven by how much light there is. But it's a lot more complicated and subtle than that.
"The guard cells that operate the stomata must be getting information from the leaf," Berry said.
Stomata seem to be picking up and responding to signals about not only sunlight, but CO2 and other important changes in the leaves.
"The importance as I see it is this gives us a starting point to make a model," said Berry.
That model can then be incorporated into climate models to better represent reality. "It's not complete because there are other things going on -- like drought stress and CO2 concentrations," he said.
As for just how universal plant stomata behavior is, Berry is pretty confident.
"Stomata have been around for 300 million years," said Berry. "Fossil stomata look pretty much like current stomata."
"It's a very elegant piece of work," said Dennis Baldocchi, professor of biometeorology at the University of California, Berkeley. "It's quite profound work. In the past people looked at gross drivers... . This will help us develop models."
