By Tracy Gregg
Buffalo, NY – Dan Lenard's commentary of Dec. 8 gave me chills. His statements that global warming is a "theory" and that the end of the Ice Age "shreds the paradigm of technology causing global climate change" are both completely, irrevocably wrong. Mr. Lenard is either filled with misunderstanding of how science works, or is intentionally trying to mislead the listening audience. Either possibility fills me with dread.
Global warming is not a "theory." It is a fact. According to UB's expert on climate change, Prof. Jason Briner, of the warmest years ever on record, 8 of them have been in the last decade. We can indeed accurately measure Earth's temperatures over the last half-a-million years, and the time frame gets longer every year. How? By measuring bubbles trapped in ice that formed in Antarctica hundreds of thousands of years ago.
Antarctica hosts the largest continental ice cap in the world, and that ice cap is ancient. Drill cores have recovered ice older than 720,000 years. Within that ice are tiny bubbles, trapped when the ice formed. The process is simple, and easy to observe in a Buffalo winter. Snow falls, and between the snowflakes are little pockets of air. More snow falls, and more, and more, and eventually the weight of the overlying snow presses the snow at the bottom into water or ice, if it's cold enough. The air pockets between the snowflakes become bubbles, trapped in the ice.
So we can directly measure the composition of Earth's atmosphere from over 700,000 years ago, up to the present, using these Antarctic ice cores. The ice itself provides a direct measure of global average temperatures, obtained by looking at the oxygen atoms locked within the ice molecules. And from those ancient atmospheric bubbles, we can measure the amount of carbon dioxide in the atmosphere when the snow originally fell comparing it with today's global temperatures and atmospheric composition.
What do these measurements reveal? That the global average temperatures today are, in fact, higher than they've been for at least 6000 years a time frame encompassing the legendary crumbling of the walls of Jericho mentioned by Mr. Lenard. That the Earth's atmosphere contains more carbon dioxide and methane today than it has at any time since Homo sapiens appeared on the planet. Both are greenhouse gases known to raise the global temperature. The ice cores show that as carbon dioxide content goes up, so does the temperature.
These are facts. One can choose to disbelieve them, but that would put one in the company of those who choose to believe the Earth is flat, in spite of all the evidence to the contrary.
Mr. Lenard asked that someone explain to him why the last Ice Age ended, before anyone ever lit a match. I'd be happy to. But first I'd like to inform him that, during the last Ice Age, the temperatures of the tropical oceans were only about 3 degrees Fahrenheit less than their temperatures today. Today, global average temperatures are 1.3 degrees higher than they've been since the last Ice Age ended. Earth's climate systems perform a delicate dance, and it doesn't take much of a sidestep to throw the whole thing out of whack.
So why did the Ice Age end? Earth goes through variations in its orbit over thousands of years similar to the way a child's top wobbles as it spins. This is fact, not theory. Because of these wobbles, sometimes the Earth receives more energy from the Sun, sometimes less. The last Ice Age ended because Earth went through a simple, subtle, and regular variation in its orbit: no matches required. The difference between now and then is that now, human beings billions of us are lighting matches, generating more greenhouse gases than Earth's atmosphere has contained in millennia.
We're forcing the temperature up, at a time and rate well outside of Earth's natural, normal cycles. As Mr. Lenard says, we are responsible for the protection of our "precious little blue sphere" and, as every child will tell you, playing with matches is not a responsible act.
Listener-Commentator Tracy Gregg is an associate professor of Geology at the University at Buffalo. She was assisted by two colleagues in the Geology Department, Jason Briner and Chuck Mitchell.