Tuesday, October 17, 2023

On Today's Climate Change: It Is Real No Matter The Denial by Some

Environmental & Science Education, STEM, Global Change, Climate Change, Sustainability, Science & Society, Evolutionary Biology, Biodiversity, Models

Ed Hessler

If you are a reader of the Minneapolis Star Tribune, you've likely read a recent opinion piece by climatologist Michael Mann. There it was titled "No the Climate Hasn't  'Always Changed' Like This."  It is behind a Star Tribune paywall (9-28-2023) and was republished from the Los Angeles Times where you can read it again or for the first time if you haven't. 

Mann begins with the common refrain from climate deniers "'The climate is always changing!'" We've survived before and will do it again and apparently again.

His essay calls attention to rates of carbon dioxide change which is different from the deniers reference points: Earth temperature and atmospheric carbon dioxide concentration.

Mann notes that climatologists who study deep time point out a "natural comparison for the rapid greenhouse-trend we are seeing now. It is known as the Paleocene-Eocene Thermal Maximum (PETM)," and event that happened after the extinction of the dinosaurs. It occurred 56 million years ago. (emphasis mine). The cause was the dumping of  tons of "carbon dioxide into the atmosphere from volcanic eruptions in Iceland."

In a mere 10,000 years - the atmosphere was already a steamy one at 80 degrees F it rose to  90 degrees F. The hooker is that it occurred about "10 times slower than warming today." (emphasis mine).

Now this turned out to be good for humans or our human ancestors which were small, underfoot and overhead in the trees. We were not present then. Here is an equation: Dinosaur extinction + "stifling events of the PETM warming'" =  humans not ever been here. 

Mann notes other extinctions, the recent warming period only 18,000 years ago. Mann describes the drivers but "the planet warmed by about 10 degrees F " in the following 8,000 years. How did we make it - humans and some of our relatives were present.  It was due to our big brains which allowed us to adapt. Remember, in this short period there were many extinctions, including the charismatic wooly mammoths and mastodons.

What has kept us afloat long enough to construct societies with all their respective services "was built around this period of stability." So I suppose some might use this as evidence (somehow) that we made it then and will now but "the dinosaurs and the mastodons" were caught by rapid climate change to which they were not adapted, just like today , the imminent future.

By the way and this is important, the models used in these two paleoclimate events allow climatologists today to test their models and they pass.

Mann writes "the end result is that we can trust these models to peer into our climate future. They tell us that we can avoid (such a tragedy), IF we reduce carbon emissions substantially over the  next decade."  We live in a fragile moment, one fragile enough to be referred to as a critical juncture. (Caps and underline mine).

This is an important essay backed by considerable lines of good evidence.

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