Plants may boost temperatures by 5 degrees Celsius: study

Variations in how plants respond to carbon dioxide may result in temperatures that are 3 to 5 degrees Celsius warmer by the middle of the century than previously estimated, researchers, including one of Indian-origin, say.
The projected temperature increase is more than half the change forecast by the Intergovernmental Panel on Climate Change (IPCC) under the business-as-usual model, researchers said.
The biggest temperature changes were projected to occur over needleleaf forests, tundra and agricultural land used to grow crops.
"We often underestimate the role of vegetation in extreme temperature events as it has not been included in enough detail in climate models up until this point," said Jatin Kala from Murdoch University in Australia.

"These more detailed results are confronting but they help explain why many climate models have consistently underestimated the increase in the intensity of heatwaves and the rise in maximum temperatures when compared to observations," said Kala.
Researchers looked at data from 314 plant species across 56 field sites. In particular, they studied stomata, small pores on plant leaves that take in carbon dioxide and lose water to the atmosphere.

Previously, most climate models assumed all plants trade water for carbon in the exactly same way, ignoring experimental evidence showing considerable variation among plant types, researchers said.
By not accounting for these differences, models have likely over-estimated the amount of water lost to the atmosphere in some regions, they said.

If plants release less water there is more warming and a consequent increase in heat wave intensity.
The study is unique because, for the first time, it used the best available observations to characterise different plants water-use strategies within a global climate model, researchers said.
"These world-first results will have significant impact on the development of climate models around the world," said Andy Pitman from University of New South Wales in Australia.
"This is a fantastic example of STEM-based science bringing together the ecological and climate modelling communities; two sectors which rarely work hand-in-hand," said Pitman.
The findings were published in the journal Nature Scientific Reports.