Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

More CO2 leads to less clouds

04.09.2012
A new feedback mechanism operating between vegetation and cloud formation could enhance the climate change

The warmer the air, the more water can evaporate: a simple relationship familiar to us from everyday life. Researchers from Germany and the Netherlands have now established that this not always the case: although an increase in the greenhouse gas CO2 makes the climate warmer, it also allows less water to evaporate.


Presumably fewer clouds will develop in the future over the grass: The increase in carbon dioxide in the atmosphere causes an evaporation decrease of plants. As a result fewer cumulus clouds form, more sunlight reaches the ground - the climate change intensifies.

Picture: Bart van Stratum

Plants, with their billions of tiny leaf pores, are the cause of this apparent contradiction. They influence the gas and moisture content of the air around them. Using new calculations of an atmospheric model, the researchers found that this sets in motion a cascade of processes, finally resulting in global warming.

“We wanted to know how the foreseeable rise in CO2 would affect cloud formation in temperate climate zones and what part the vegetation plays in this,” says Jordi Vilà-Guerau de Arellano from the University of Wageningen in the Netherlands. Working with colleagues from the Max Planck Institutes for Chemistry and Meteorology, the geophysicists made use of, for the first time, a computer model that takes account of the soil, water cycle, atmosphere and growth processes of plants. The model results highlight how local and daily variable processes, through turbulence, can influence the atmosphere on larger scales.

The scientists simulated three scenarios for their analysis: a doubling of the CO2 in the atmosphere from the current 0.038% to 0.075%, an increase in the average global temperature by two degrees Celsius and a combination of both. The calculations represent the conditions expected for the year 2100 and compared to 2003 values based on scenarios from the Intergovernmental Panel on Climate Change (IPCC).

The researchers established that some land-vegetation-atmosphere exchange processes respond more strongly to increasing CO2 and climate change than others. Doubling the CO2 in the atmosphere actually starts a cascade of processes beginning with the physiological response of plants to the higher CO2 concentration. The trigger of the chain of events is that plants regulate the exchange of water vapor and carbon dioxide with the atmosphere by the opening and closing of the leaf pores - the stomata.

At higher CO2 concentrations plants close their stomata

The cascade starts harmless: in the double CO2 scenario, the stomata close earlier since the plants can assimilate the necessary CO2 for photosynthesis more optimally. As a result, less moisture is evaporated by the plants and there is overall less water vapour introduced into the atmosphere.

Consequently, fewer cumulus clouds are formed, which means that the Earth's surface becomes warmer, as the sun's rays hit it directly and are not reflected by clouds. Then, warmer air creates more turbulence in the atmosphere near the surface, and in consequence there is more heat and less moisture transported. The earth and the atmosphere thus heat up through the plants' response to the higher CO2 levels.

The researchers have thus found another feedback mechanism in the climate system, a self-reinforcing process. This feedback mechanism did not develop in the second scenario, in which the atmosphere only warms by two degrees Celsius without the effect of higher concentrations of the greenhouse gas CO2 on plants.

Evaporation will fall by 15%

The researchers then simulated a third scenario in which they increased both the CO2 levels and the temperature. “Positive effects on cloud formation include the ability of the warmer atmosphere to hold more water or increase the growth of biomass. However, they are only partly able to compensate for the reduction in cloud formation,” according to Jordi Vilà. “Evaporation will fall by 15%. The atmospheric boundary layer dries out, and fewer clouds form,” adds Jos Lelieveld, Director at the Max Planck Institute for Chemistry in Mainz.

The study thus shows that diminished evaporation from plants has a direct impact on cloud formation. Chiel van Heerwaarden from the Max Planck Institute for Meteorology emphasizes: “The calculations show an important feedback mechanism between the vegetation and physical climate processes.” In future, the researchers want to extend their analysis to the Amazon to test the effects of increasing CO2 levels on tropical regions.

SB/NW

Original Publication

Modelled suppression of boundary-layer clouds by plants in a CO2-rich atmosphere
Jordi Vilà-Guerau de Arellano, Chiel C. van Heerwaarden und Jos Lelieveld
Nature Geoscience, 2. September 2012

Dr. Susanne Benner | Max-Planck-Institut
Further information:
http://www.mpic.de/

More articles from Earth Sciences:

nachricht NASA eyes Pineapple Express soaking California
24.02.2017 | NASA/Goddard Space Flight Center

nachricht 'Quartz' crystals at the Earth's core power its magnetic field
23.02.2017 | Tokyo Institute of Technology

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>