• Print friendly
• E-mail a friend
• Contact Us
• Social Networks
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
  • 
• Stock Market
  • Weather
  • Gas Prices
  • Flight Info
  • Lottery
  • Recipes
  • Soccer

Global Warming, Global Cooling,

Time Cover Story Offers No Evidence Of Human-Driven Warming

By Dennis Avery

Thursday, March 30, 2006

Time devotes its latest cover to the "near-certainty" that humans are causing dangerous global warming. However, Time offers evidence only of a warming, which could be either man-made or natural.

Based on historic and geophysical evidence, Time's new cover story is likely to be as wrong as its 1974 cover story touting global cooling! Newsweek did one the next year.

Neither magazine understands the moderate; natural climate cycle that history tells us has dominated the last 2000 years of Earth's temperature variations:

• The Romans grew wine grapes in England in the 1^st century, during the Roman Warming. Then, during the Dark Ages, Britain was too cold for grapes.

• The Britons themselves grew wine grapes in England in the 11^th and 12^th centuries, during the Medieval Warming. The Domesday Book, compiled right after the Norman Invasion of 1066, records more than 70 vineyards. During the following Little Ice Age, London held ice festivals instead of wine tastings.

• It's not warm enough yet during the Modern Warming for a British wine industry, but the grape growers are succeeding two years out of ten–and hopeful.

• That makes three global warmings in 2000 years right from our history books.

In the 1980s, we were surprised by the first long ice cores from both Greenland and the Antarctic, which gave us 400,000 years of the Earth's detailed temperature history in their ice layers. We had expected to find the big Ice Ages and the warm interglacial periods like our own. We had not expected to find a moderate, natural 1500-year cycle running through it all, even through the big Ice Ages.

The natural warmings raise Earth's temperatures 1 to 2 degrees C at the latitude of New York for 400—800 years. The coolings that follow drop our temperatures 1—2 degrees below the mean for a similar length of time.

Since then, scientists have found the 1500-year cycle in tree rings; cave stalagmites and the microfossils of seabed sediments. Prehistoric villages moved up and down the Alps and Andes mountainsides while glaciers worldwide advanced and retreated, all in time with the cycle.

The North American pollen database shows nine complete reorganizations of our trees and plants in the past 14,000 years, or a cycle every 1,650 years. In my home state of Michigan, pollen shows that the numbers of warmth-loving beech trees yielding first to the cold-tolerant oaks and then to cold-adapted pine trees. Currently, with the world 150 years into the Modern Warming, the pine trees are being discouraged, the oaks are proliferating, and the beech trees are waiting another turn.

The solar-created carbon and beryllium isotopes in the ice tell us the cycle is linked to a similar cycle in the sun's irradiance. We had known for centuries that the coldest parts of the Little Ice Age occurred when there were virtually no sunspots. Now, space satellites are documenting small variations in what we used to think was an unchanging sun.

Time magazine has no such hard evidence to support human-induced warming. Theory says more CO₂ will mean warmer temperatures, but no one knows whether the CO₂ "X-factor" is tiny or huge. The modest net warming since 1940 argues against a big CO₂ factor. So does the erratic warming pattern, with a cooling from 1940 to 1979 and then a spurt of warming.

A warming driven by industrial CO₂ should have started after 1940, and increased strongly and steadily. The climate models all assume a big CO₂ factor, without evidence.

The UN Intergovernmental Panel on Climate Change claims to have found a "human fingerprint", but has offered no evidence to support the claim.

The evidence is all on the side of the natural cycle.

Time's cover story seems overheated. The UN panel's widely publicized scenario of an 11-degree C warming driven by CO₂ seems frantic.

Dennis T. Avery, is a senior fellow with the Hudson Institute in Washington, DC and the Director for Global Food Issues (www.cgfi.org). He was formerly a senior analyst for the Department of State. Dennis can be reached at: cgfi@hughes.net Opinion 2007 2006