September 19, 2003
by Dennis T. Avery
Dr. Jan Veizer, a geologist at the University of Ottawa, has reconstructed the earth's temperature record for the last 500 million years, using the fossilized remains of seashells. He was surprised to find a major global warming-cooling cycle every 135 million years, a time period that coincides with no other earthly phenomenon.
Then Dr. Nir Shaviv, an astrophysicist at the University of Toronto, told him that cosmic rays striking the earth cycle up and down over 135 million years as our solar system passes through one of the bright arms of the Milky Way. The Milky Way has intense levels of cosmic rays that tend to cool the earth, stimulating the formation of low-level clouds that reflect heat back into space. (High-level clouds tend to trap heat and warm the planet.)
Dr. Shaviv says the changes in cosmic ray intensity, due to passing through the Milky Way, are much greater than the variations in the activity of the sun.
In a unique, cross-disciplinary study recently published by the Geophysical Society of America, Veizer and Shaviv conclude that 75 percent of the earth's temperature variability in the past 500 million years is due to changes in our bombardment by cosmic rays as we pass in and out of galactic spiral arms. (They note that the sun continued to brighten during the 20th century. It may have accounted for about one-third of the observed warming since 1900.)
Veizer and Shaviv conclude that a doubling of today's CO2 levels would only increase global temperatures a modest 1.4 degree Fahrenheit. The UN's Intergovernmental Panel on Climate Change, in dramatic contrast, estimates two to seven times as much warming from such a CO2 increase (2.7 to 9.9F).
The two scientists warn that the billion-dollar Global Circulation computer models that predict dangerous global warming from CO2 increases are particularly weak at modeling changes in clouds that matter vitally to Earth's temperatures. Cosmic rays stimulate low-lying clouds, by electrically charging tiny particles (aerosols) so they collect more water droplets from the atmosphere. More low clouds mean a cooler planet.
Increased solar activity, in contrast, tends to reduce cloud cover and stimulate heating. In addition, a more active sun also emits more solar wind. Dr. Tim Patterson, a paleoclimatologist at Canada's Carleton University, says solar wind is a stream of very high-speed charged particles that deflect the galactic cosmic rays that would otherwise strike the earth and cool it. Thus, says Dr. Patterson, the warming from the sun and the cooling from galactic cosmic rays are in a constant competition to dominate Earth's temperature.
Veizer and Shaviv found only modest linkage between the earth's temperatures and CO2 levels. In fact, CO2 levels have been as much as 18 times higher than today during the Veizer temperature record. The earth's CO2 levels were 10 times higher than today's during the frigid Ordovician glacial period about 440 million years ago. Human CO2 releases, moreover, make up only about 3 percent of the natural carbon cycle.
For those of us who value information derived from the planet itself more than we value theories and computer models, Veizer/Shaviv projection from seashells matches the modest rate of global temperature change recorded by weather satellites and high-altitude balloons over the past 22 years. (The satellites and balloons are the most accurate measurements ever taken of the temperatures in the bulk of the atmosphere, far from urban heat islands.)
Iceberg debris from the floor of the North Atlantic says we've had nine moderate global warmings and coolings over the last 12,000 years, in a 1,500 year cycle that coincides exactly with a cycle in the magnetic activity of the sun. Veizer and Shaviv say three-fourths of the earth's temperature change is driven by cosmic rays from around the galaxy. Neither study finds much impact on the earth's temperatures from CO2 changes.
Meanwhile, the computer modelers and "researchers" willing to scare us about CO2 now divvy up more than $4 billion per year in government grants. The eco-activist organizations probably reap at least that much per year from CO2 scaring in memberships, subscriptions, and foundation grants from the frightened.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.
Home | Learn About Hudson | Hudson Scholars | Find an Expert | Support Hudson | Contact Information | Site Map
Policy Centers | Research Areas | Publications & Op-Eds | Hudson Bookstore
Hudson Institute, Inc. 1015 15th Street, N.W. 6th Floor Washington, DC 20005
Phone: 202.974.2400 Fax: 202.974.2410 Email the Webmaster
© Copyright 2013 Hudson Institute, Inc.