Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

’No doubt’ human activity is affecting global climate

03.12.2003


Two of the nation’s premier atmospheric scientists, after reviewing extensive research by their colleagues, say there is no longer any doubt that human activities are having measurable-and increasing-impacts on global climate. Their study cites atmospheric observations and multiple computer models to paint a detailed picture of climate changes likely to buffet Earth in coming decades, including rising temperatures and an increase in extreme weather events, such as flooding and drought. The study appears December 5 in Science as part of the journal’s "State of the Planet" series.


Drought and other extreme climate events may become more likely in the future because of global climate change. (Photo by Carlye Calvin)


Motor vehicles are a significant source of carbon dioxide. Two of the nation’s premier atmospheric scientists now say there is "no doubt" that carbon dioxide emissions, along with other human-related activities, are impacting global climate. (Photo by Carlye Calvin)



The coauthors-Thomas Karl, director of NOAA’s National Climatic Data Center, and Kevin Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research (NCAR)-conclude that industrial emissions have been the dominant influence on climate change for the past 50 years, overwhelming natural forces. The most important of these emissions is carbon dioxide, a greenhouse gas that traps solar radiation and warms the planet.

"There is no doubt that the composition of the atmosphere is changing because of human activities, and today greenhouse gases are the largest human influence on global climate," they write. "The likely result is more frequent heat waves, droughts, extreme precipitation events, and related impacts, e.g., wildfires, heat stress, vegetation changes, and sea-level rise which will be regionally dependent."


Karl and Trenberth estimate that, between 1990 and 2100, there is a 90 percent probability that global temperatures will rise by 1.7 to 4.9 degrees Celsius (3.1 to 8.9 degrees Fahrenheit), because of human influences on climate. Such warming would have widespread impacts on society and the environment, including continued melting of glaciers and the great ice sheets of Greenland, inundating the world’s coasts. The authors base their estimate on computer model experiments by climate scientists, observations of atmospheric changes, and recorded climate changes over the past century.

However, there is still large uncertainty in understanding the global climate and how it will change, says Karl. If temperatures rise 1.7 degrees, the expected changes would be relatively small, whereas a 4.9-degree increase could bring drastic impacts, some of which may be unforeseen.

Carbon dioxide levels in the atmosphere have risen by 31 percent since preindustrial times, from 280 parts per million by volume (ppmv) to over 370 ppmv today. Other human activities, such as emissions of sulfate and soot particles and the development of urban areas, have significant but more localized climate impacts. Such activities may enhance or mask the larger-scale warming from greenhouse gases, but not offset it, according to the authors.

If societies could successfully cut emissions and stabilize carbon dioxide levels in the atmosphere, temperatures would still increase by an estimated 0.5 degree C (0.9 degree F) over a period of decades, Karl and Trenberth warn. This is because greenhouse gases are slow to cycle out of the atmosphere. "Given what has happened to date and is projected in the future, significant further climate change is guaranteed," the authors state.

If current emissions continue, the world would face the fastest rate of climate change in at least the last 10,000 years. This could potentially alter ocean current circulations and radically change existing climate patterns. Moreover, certain natural processes would tend to accelerate the warming. For example, as snow cover melts away, the darker land and water surface would absorb more solar radiation, further increasing temperatures.

Karl and Trenberth say more research is needed to pin down both the global and regional impacts of climate change. Scientists, for example, have yet to determine the temperature impacts of increased cloud cover or how changes in the atmosphere will influence El Niño, the periodic warming of Pacific Ocean waters that affects weather patterns throughout much of the world. The authors call for multiple computer model studies to address the complex aspects of weather and climate. The models must be able to integrate all components of Earth’s climate system-physical, chemical, and biological. This, in turn, will require considerable international cooperation and the establishment of a global climate monitoring system to collect and analyze data.

Because of the broad range of potential change in temperature, it’s extremely important to ensure that we have a comprehensive observing system to track unforeseen changes and variations, says Karl.

"Climate change is truly a global issue, one that may prove to be humanity’s greatest challenge," the authors conclude. "It is very unlikely to be adequately addressed without greatly improved international cooperation and action."


To subscribe via e-mail send name, title, affiliation, postal address, fax, and phone number to yvonnem@ucar.edu.

Anatta | UCAR
Further information:
http://www.ucar.edu/communications/newsreleases/2003

More articles from Earth Sciences:

nachricht New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz

nachricht Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Behavior-influencing policies are critical for mass market success of low carbon vehicles

17.07.2018 | Power and Electrical Engineering

Plant mothers talk to their embryos via the hormone auxin

17.07.2018 | Life Sciences

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>