Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Geoengineering the climate would reduce vital rains

04.11.2013
Although a significant build-up in greenhouse gases in the atmosphere would alter worldwide precipitation patterns, a widely discussed technological approach to reducing future global warming would also interfere with rainfall and snowfall, new research shows.

The international study finds that a massive increase in greenhouse gases and warming of the planet would spur a nearly 7 percent global increase in precipitation, on average, compared to preindustrial conditions.


Monsoon rainfall wets Beijing streets and passersby in 2011. New research indicates geoengineering to reduce global warming would also reduce average global precipitation. Credit: Sierra F.

But, trying to resolve the problem through “geoengineering” could result in important seasonal rainfalls, known as monsoonal rains, in North America, East Asia, and other regions dropping by 5-7 percent compared to preindustrial conditions. Globally, average precipitation could decrease by about 4.5 percent.

“Geoengineering the planet doesn’t cure the problem,” said Simone Tilmes of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., and lead author of the new study. “Even if one of these techniques could keep global temperatures approximately balanced, precipitation would not return to normal conditions.”

As concerns have mounted about climate change, scientists have studied geoengineering approaches to reduce future warming. Some of these would capture carbon dioxide before it enters the atmosphere. Others would attempt to shade the atmosphere by injecting sulfate particles into the stratosphere or even launching mirrors into orbit with the goal of reducing global surface temperatures.

The new study focuses on the second set of approaches, those that would shade the planet. It warns however, that Earth’s climate would not return to its preindustrial state even if the warming itself were successfully mitigated.

“It’s very much a pick-your-poison type of problem,” said John Fasullo, also of NCAR and a study co-author. “If you don’t like warming, you can reduce the amount of sunlight reaching the surface and cool climate. But if you do that, large reductions in rainfall are unavoidable. There’s no win-win option here.”

The study appears in an online issue of the Journal of Geophysical Research: Atmospheres, published this week by the American Geophysical Union. It was written by an international team of scientists from NCAR and 14 other organizations, and was funded in part by the National Science Foundation (NSF), which sponsors NCAR. The team used, among other tools, the NCAR-based Community Earth System Model, which is funded by NSF and the Department of Energy.

Future carbon dioxide, with or without geoengineering

The research team turned to 12 of the world’s leading climate models to simulate global precipitation patterns if the atmospheric level of carbon dioxide, a leading greenhouse gas, reached four times the level of the preindustrial era. They then simulated the effect of reduced incoming solar radiation on the global precipitation patterns.

The scientists chose the artificial scenario of a quadrupling of carbon dioxide levels, which is on the high side of projections for the end of this century, in order to clearly draw out the potential impacts of geoengineering.

In line with other research, they found that an increase in carbon dioxide levels would significantly increase global average precipitation, although there would likely be significant regional variations and even prolonged droughts in some areas.

Much of the reason for the increased rainfall and snowfall has to do with greater evaporation, pumping more moisture into the atmosphere as a result of more heat being trapped near the surface.

The team then took the research one step further, examining what would happen if a geoengineering approach partially reflected incoming solar radiation high in the atmosphere.

The researchers found that precipitation amount and frequency, especially for heavy rain events, would decrease significantly. The effects were greater over land than over the ocean, and particularly pronounced during months of heavy, monsoonal rains. Monsoonal rains in the model simulations dropped by an average of 7 percent in North America, 6 percent in East Asia and South America, and 5 percent in South Africa. In India, however, the decrease was just 2 percent. Heavy precipitation further dropped in Western Europe and North America in summer.

A drier atmosphere

The researchers found two primary reasons for the reduced precipitation.

One reason has to do with evaporation. As Earth is shaded and less solar heat reaches the surface, less water vapor is pumped into the atmosphere through evaporation.

The other reason has to do with plants. With more carbon dioxide in the atmosphere, plants partially close their stomata, the openings that allow them to take in carbon dioxide while releasing oxygen and water into the atmosphere. Partially shut stomata release less water, so the cooled atmosphere would also become even drier over land.

Tilmes stressed that the authors did not address such questions as how certain crops would respond to a combination of higher carbon dioxide and reduced rainfall.

“More research could show both the positive and negative consequences for society of such changes in the environment,” she said. “What we do know is that our climate system is very complex, that human activity is making Earth warmer, and that any technological fix we might try to shade the planet could have unforeseen consequences.”

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this early view article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50868/abstract

Or, you may order a copy of the final paper by emailing your request to Thomas Sumner at tsumner@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release is under embargo.

Title

“The hydrological impact of geoengineering in the Geoengineering Model Intercomparison Project”

Authors:

Olivier Boucher and Michael Schulz
Laboratoire de Météorologie Dynamique, IPSL, CNRS/UPMC, Paris, France
Jason N. S. Cole
Canadian Centre for Climate Modeling and Analysis, Environment Canada, Toronto, Ontario, Canada
Charles L. Curry
School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada
Andy Jones and Jim Haywood
Met Office Hadley Centre, Exeter, UK
Peter J. Irvine
Institute for Advanced Sustainability Studies, Potsdam, Germany;
Duoying Ji and John C. Moore
State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal University, Beijing, China.
Diana B. Karam
Laboratoire des Sciences du Climat et l’Environnement, CEA, CNRS, UVSQ, Gif-sur-Yvette, France;
Ben Kravitz, Philip J. Rasch, Balwinder Singh and Jin-Ho Yoon
Pacific Northwest National Laboratory, Richland, Washington, USA
Ulrike Niemeier and Hauke Schmidt
Max Planck Institute for Meteorology, Hamburg, Germany
Alan Robock
Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey, USA
Shuting Yang
Danish Meteorological Institute, Copenhagen, Denmark
Shingo Watanabe
Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
Contact information for the authors:
Simone Tilmes, Phone: +1 (303) 497-1445, Email: tilmes@ucar.edu
John Fasullo, Phone: +1 (303) 497-1712, Email: fasullo@ucar.edu
AGU Contact:
Thomas Sumner
+1 (202) 777-7516
tsumner@agu.org
NCAR/UCAR Contacts:
David Hosansky,
+1 (303) 497-8611
hosansky@ucar.edu
Zhenya Gallon
+1 (303) 497-8607
zhenya@ucar.edu

Peter Weiss | American Geophysical Union
Further information:
http://www.agu.org

More articles from Earth Sciences:

nachricht Mountain glaciers shrinking across the West
23.10.2017 | University of Washington

nachricht Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Salmonella as a tumour medication

HZI researchers developed a bacterial strain that can be used in cancer therapy

Salmonellae are dangerous pathogens that enter the body via contaminated food and can cause severe infections. But these bacteria are also known to target...

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Microfluidics probe 'cholesterol' of the oil industry

23.10.2017 | Life Sciences

Gamma rays will reach beyond the limits of light

23.10.2017 | Physics and Astronomy

The end of pneumonia? New vaccine offers hope

23.10.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>