Letter: Don't ignore human effect on globe
Melting ice in the Ilulissat fjord on the western coast of Greenland. Credit: Getty Images, 2008
The letter addressing the causes of sea-level rise ["Global warming: the long, long view," March 26] is correct that the sea level has been rising naturally since the end of the last Ice Age, but it misses the point about the human impact from industrialization.
Sea level rise is driven by melting glacial ice. Measurements made by scientists over the last several decades show clearly that most glaciers are melting and that oceans are warming at an ever-increasing rate, which correlates with the rise in carbon dioxide and other greenhouse gases produced by human activities.
Besides the warming between ice ages triggered by changes in the Earth's orbit, geologists have identified many episodes of rapid climate warming in the past caused by the release of carbon dioxide during times of extreme volcanic activity (the last of which occurred millions of years before humans were on the Earth). A recent study published by the Geological Society of America estimates that the amount of carbon dioxide that will be released from the burning of fossil fuels by the end of the 21st Century will equal in volume the amount of greenhouse gas released during one of these extreme, climate-altering volcanic events.
What's the difference? It takes massive volcanic eruptions tens of thousand of years to produce the same amount of greenhouse gas that humans will produce in just 200 years. The acceleration of climate change and resulting sea level rise caused directly by human activity may be unprecedented in the history of the Earth. In this case, Hummers do trump Mother Nature!
J. Bret Bennington, West Hempstead
Editor's note: The writer is a geology professor at Hofstra University.
