Rising CO2 levels likely to change vegetation locally more so than globally: study

Jun 28, 2012 by Bob Yirka report
Transitions between vegetation states projected for the period 1850-2100. Image (c) Nature (2012) doi:10.1038/nature11238

(Phys.org) -- In all the talk about global warming as a result of human created CO2 emissions, it seems other impacts of higher levels of carbon dioxide on the environment tend to get overlooked. One of those impacts, argue German researchers Steven Higgins and Simon Scheiter, who have been building models showing what impact such levels might have on vegetation, is a likely shift away from deserts and grasslands to more woody areas and forests. The two have written a paper describing their findings which has been published in the journal Nature.

Everyone that’s been to grade school knows that what we breathe out, plants breath in, and vice-versa, thus more of what we breath out, i.e. (though from another source) should mean more for plants to breathe in, which should indicate better plant growth, more plant growth, or the switch from low level breathers to those that thrive on more CO2 in the air. Higgins and Scheiter suggest at least locally, that it’s the last possibility that might create the most change over the coming decades as the Earth’s vegetation slowly responds to finding more CO2 in the air.

The two restricted their area of study to the African continent and found first that because grasses that live in the savannah tend to need less CO2 to thrive than do trees, there are large swaths of the continent that favor savannah, which is demonstrated by the abundance of with the occasional stand of trees. Adding more CO2 to the mix is likely to change that balance they show, to favor tree growth over grasses, leading to more woodland. They also found that increased CO2 levels also tend to favor grasslands over , which for Africa should mean decreasing desert sizes.

Throwing a wrench into the whole works though is water, of course, in the form of rainfall. If there is no rain, a desert will always be desert. But because of changes in topography, rainfall levels can vary dramatically over short distances leading to differences in the impact of rising CO2 levels. In areas with higher CO2 and adequate rainfall, the trend will be from savannah to , whereas in similar areas with less rainfall, tress might not be able to survive even with the addition of more CO2, thus the area would remain savannah.

This all means, the two write, that Africa is likely to see significant change over the next few decades as CO2 levels in the atmosphere continue to rise, causing significant changes to local areas of vegetation growth, depending on rainfall amounts, which will of course impact wildlife and the way the land is used by the people that live there, in ways that are impossible to predict.

Explore further: Uncertainty about sea levels to last 10 more years, experts say

More information: Atmospheric CO2 forces abrupt vegetation shifts locally, but not globally, Nature (2012) doi:10.1038/nature11238

Abstract
It is possible that anthropogenic climate change will drive the Earth system into a qualitatively different state1. Although different types of uncertainty limit our capacity to assess this risk2, Earth system scientists are particularly concerned about tipping elements, large-scale components of the Earth system that can be switched into qualitatively…

Related Stories

Global warming: New study challenges carbon benchmark

Sep 28, 2011

The ability of forests, plants and soil to suck carbon dioxide (CO2) from the air has been under-estimated, according to a study on Wednesday that challenges a benchmark for calculating the greenhouse-gas ...

US rivers and streams saturated with carbon

Oct 17, 2011

Rivers and streams in the United States are releasing enough carbon into the atmosphere to fuel 3.4 million car trips to the moon, according to Yale researchers in Nature Geoscience. Their findings could ...

Araucarias gauge ancient levels of carbon dioxide

Apr 29, 2011

One way of telling how much carbon dioxide was in the atmosphere in the past is by counting pores (or stomata) in leaves – the tiny openings plants use to absorb CO2 and lose water. It may seem far-f ...

Deforestation reduces rainfall in Africa

Sep 19, 2011

Deforestation in the rainforests of West Africa reduces rainfall over the rest of the forest, according to new University of Leeds research published in Geophysical Research Letters.

Recommended for you

Researchers question emergency water treatment guidelines

13 hours ago

The Environmental Protection Agency's (EPA's) recommendations for treating water after a natural disaster or other emergencies call for more chlorine bleach than is necessary to kill disease-causing pathogens ...

European climate at the +2 C global warming threshold

15 hours ago

A global warming of 2 C relative to pre-industrial climate has been considered as a threshold which society should endeavor to remain below, in order to limit the dangerous effects of anthropogenic climate change.

User comments : 0

More news stories

Melting during cooling period

(Phys.org) —A University of Maine research team says stratification of the North Atlantic Ocean contributed to summer warming and glacial melting in Scotland during the period recognized for abrupt cooling ...