. 24/7 Space News .
Calibrating The Human Impact Within Earth's Climate Record

"Tthe countervailing effects of greenhouse gases and sulfur emissions undercut comments by climate change skeptics, who argue that the rapid increase in atmospheric concentrations of greenhouse gases between the end of World War II and the early 1970s had little effect on temperature," says Dr. Robert K. Kaufmann of Boston University's Center for Energy and Environmental Studies.
 Washington - Jan 29, 2002
Human activity has affected Earth's surface temperature during the last 130 years, according to a study published this month by the Journal of Geophysical Research.

Dr. Robert K. Kaufmann of Boston University's Center for Energy and Environmental Studies and Dr. David I. Stern of the Australian National University's Centre for Resource and Environmental Study analyzed historical data for greenhouse gas concentrations, human sulfur emissions, and variations in solar activity between 1865 and 1990.

The greenhouse gases studied included carbon dioxide, methane, nitrous oxide, and chloroflurocarbons 11 and 12.

Using the statistical technique of cointegration, the scientists compared these factors over time with global surface temperature in both the northern and southern hemispheres.

Cointegration techniques are not confused by variables that tend to increase or decrease over time or contain some poorly measured observations. As such this is the first study to make a statistically meaningful link between human activity and temperature, independent of climate models, Kaufmann notes.

They found that eliminating any one variable -- greenhouse gases, human sulfur emissions, or solar activity -- made the errors larger; that is, all of those factors taken together are needed to explain changes in Earth's surface temperature.

They found also that the impact of human activity has been different in the two hemispheres. In the north, the warming effect of greenhouse gases was almost exactly offset by the cooling effect of sulfur emissions, making the temperature effects difficult to observe. In the southern hemisphere, where human sulfur emissions are lower, the effects are easier to see, they write.

Kaufmann says, "the countervailing effects of greenhouse gases and sulfur emissions undercut comments by climate change skeptics, who argue that the rapid increase in atmospheric concentrations of greenhouse gases between the end of World War II and the early 1970s had little effect on temperature."

During this period, he says, "the warming effect of greenhouse gases was hidden by a simultaneous increase in sulfur emissions. But, since then, sulfur emissions have slowed, due to laws aimed at reducing acid rain, and this has allowed the warming effects of greenhouse gases to become more apparent."

Analysis of the data indicates that doubling the atmospheric concentration of carbon dioxide from its preindustrial level will increase will increase northern hemispheric temperature by 2.3 to 3.5 degrees Celsius [4.1 to 6.3 degrees Fahrenheit].

In the southern hemisphere, the increase will be between 1.7 and 2.2 degrees Celsius [3.1 and 4 degrees Fahrenheit], the scientists say, noting that this doubling is expected to be achieved over the next century.

Kaufmann observes that while to some, these projected changes may seem small, during the last ice age, more than 15,000 years ago, Earth's global temperature was only 3 to 5 degrees Celsius [5 to 9 degrees Fahrenheit] cooler than it is now.

The paper by Robert K. Kaufmann and David I. Stern, "Cointegration analysis of hemispheric temperature relations," appears in the Journal of Geophysical Research (Atmospheres) in January 2002. Its citation, which is to the online version, is Volume 107, Number D2, 10.1029JD000174, 2002.

Related Links
Centre For Resource and Environmental Studies
Boston University
American Geophysical Union
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

Study Shows Early Signals Of Climate Change In Earth's Cold Regions
Boulder CO - Dec 10, 2001
Global mean temperatures have risen one degree Fahrenheit over the past 100 years, with more than half of the increase occurring in the last 25 years, according to University of Colorado at Boulder Senior Researcher Richard Armstrong.



Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only














The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.