I'm a little behind reading my National Geographic magazines. But I recently read an article in the December 2012 issue called "Searching for Doggerland" that really grabbed my attention. It stated that during the last ice age some 18,000 years ago, the seas around northern Europe were about 400 feet lower than they are today because so much water was tied up in glaciers.

Interestingly, England and Ireland then were actually part of the European continent. A large area now under water between England and Ireland and the continental Europe of today was dry land covered by ice. In recent years, archeologists studying the area gave it the name, Doggerland.

As the glaciers began to recede as a result of global warming (it's called climate change), people began to migrate to the area in search of food, places to live, and whatever else nomadic people do.

But guess what?

As the glaciers continued to melt, the sea level rose and by about 8000 years ago, Doggerland was mostly under water and England and Ireland had become islands. The inhabitants were forced to migrate to England, Ireland, or the European continent. Archeologists searching the reasonably shallow waters of the North Sea and the English Channel (Doggerland) have found animal bones and artifacts of a fishing culture that includes human burial grounds.

Let's do the numbers. A sea level rise of 400 feet in 10,000 years is about one-half inch per year. That doesn't seem like much. But look what happened in 10,000 years. A large area of land slowly became submerged. The earth may seem static to those of us whose life spans average 75 years. But in geologic time the earth is very dynamic. The submergence of Doggerland is an example of climate change that took place over a long period of real time but that is more like a snap of the fingers in geologic time.

Fast forward to the present. Sea level rose eight inches in the 20th century. That's only one-sixth as fast as the average seal level rise that submerged Doggerland.

However, estimates of sea level rise for the 21st century vary from 23 inches to 73 inches. The U. S. Army Corps of Engineers recommends that urban planners look at the possibility of a 60-inch rise. This is greater than the Doggerland average and would be catastrophic for large cities around the world that are built at or near existing sea levels.

Why are these estimates so high for the 21st century? An article titled "Rising Seas" in the September 2013 issue of National Geographic states the obvious. Our planet is being warmed by the release of carbon dioxide and other "greenhouse" gases from fossil fuels. According to the scientists, this global warming impacts sea levels in two ways, by thermal expansion – water increases in volume as it warms – and by the melting of glacial ice.

Nearly all prominent climate scientists believe sea levels will rise significantly this century. As a hydrologist, I agree.

There are those who believe the climate scientists are not correct and choose to deny global warming for political or financial reasons. I believe they are wrong.

That said, I don't believe global warming will seriously impact earth during the rest of my time here. It's my grandchildren that I worry about.

Unless something is done, they will see population migration from coastal areas because of the threat of inundation from rising sea levels just like what happened to Doggerland.

Do we want this for our grandchildren? No we don't.

Then let's get serious. Let's at least try to find solutions for greenhouse gas emissions and for sea level rise.

We owe our grandkids that much.