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Name: Cindi
Status: Educator
Grade: 4-5
Location: MI
Country: United States
Date: April 2007

I have been teaching/studying the geo-history of Michigan recently and came across the fact that there have been a number of Ice Ages in the history of our world. Here is what I am pondering: could this current phase of Global Warming just be a stage in the melting of icebergs, just as there was a meltdown of the glaciers that formerly covered Michigan?

Put another way: I realize that are currently gases, due to man's industry, put into the atmosphere that trap heat and give us the Global Warming effect. Could there have been some (albeit more natural) sort of gases during the melt down of previous Ice Ages?

Very good observations.

Scientists believe we are in an interglacial period---a time between ice ages. There probably is a certain amount of global warming happening as part of this natural cycle, and the giant ice sheets currently over Canada may very well be the retreating glaciers that covered Michigan several thousand years ago.

There are many factors that affect the cycle, including gases in the atmosphere, ocean circulation, particulate matter in the atmosphere, etc.

Many scientists are very concerned that the current rate of warming is so much greater than can be explained naturally. It is likely that human beings have accelerated the rate of global warming, possibly so much so that the earth is having trouble keeping up with the changes.

In other words, it is entirely possible that there is both a natural warming component and a human-caused component to the current global warming situation.

Patricia Rowe

You ask a question that will elicit responses as dogmatic as scientific. Since we were not around during the previous Ice Ages, it is difficult know exactly what happened then. It is not possible (my opinion) to say definitively that human activity alone is the cause climate changes observed in the last century. I may be wrong.

In the 1960's Paul Erlich proposed an argument that there would be mass starvation due to the large increase in population vs. food production. His model was generally accepted as true by the scientific community -- but it did not happen.

The problem with the global warming issue, (my opinion), is that there may be other equally devastating, shorter term, threats to our environment and existence that produce fewer headlines in the media. Some examples: anti-biotic resistant TB (and other) microbes, wheat and corn diseases that have made existing strains of seeds highly vulnerable and for which there are no controls.

This is not meant to minimize the importance of "global warming" but focusing on a single issue at the expense of other threats to the health and welfare of our planet is a narrow focused, dangerous strategy (my opinion).

Vince Calder

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