Today’s email brought this from someone recently returned from a cruise along the coasts of New England and Canada:
I think I heard at least two, maybe three, of the Canadian tour guides make comments regarding global warming. They are fully convinced that it is happening and that it is having a drastic effect on sea levels. They commented about eighteenth-century ship-tying rings that are now three feet underwater. They mentioned storm surges that are higher lately than they have ever seen before. They talked about winters being milder recently. Then they would say something like, “Global warming is not a theory; it’s a fact.” Not wishing to cause controversy nor having a lot of facts at my disposal, I did not say anything. I thought I would let you know this. Do you get regular feedback from Canada? Do the people there generally think that global warming is a reality?
Thinking it might be helpful to more than just my correspondent, I decided to share that response here.
We do hear fairly regularly from various people in Canada, and the range of thinking there fairly closely reflects that here in the States, though perhaps leaning a bit more to the alarmist side. Appropriate responses to some of the things they mentioned about global warming:
- “it is happening”—yes, it certainly is. And it has been since about the late 1700s (coming out of the Little Ice Age). And almost all the “global warming skeptics” I know even agree that, since around 1960 anyway, human emissions of greenhouse gases might have contributed significantly, maybe even majority, to the warming. But pre-1960 it’s extremely unlikely that human activity contributed, and even post-1960 it’s impossible to determine the balance of human versus natural warming.
- “eighteenth-century ship-tying rings that are now three feet underwater”—entirely consistent with the long-term sea-level rise rate of a little over a foot per century, stretching back thousands of years, showing no acceleration since human emissions of greenhouse gases reached rates that could conceivably contribute significantly to global warming.
- “storm surges that are higher lately”—That’s probably an overwhelmingly subjective notion, because hard data on storm surges before about the last 60 to 80 years, and surely before 1900, are extremely difficult to come by. But, yes, of course, as SL rises, storm surges will rise with it. But the added height of storm surge attributable to SLR since about 1960 (about 2.4 inches of SLR) is probably on the order of a few percent—10% would be generous. So that means that a storm surge that would have been, before 1960, 20 feet, rises to 20 feet plus about 10% of 2.4 inches, or 20 feet plus 0.24 inches, which frankly isn’t going to make a hill of beans of difference in damage done.
- “winters being milder recently”—in some places, yes, in others, no; in some years, yes, in others no. Such hand-waving claims aren’t at all scientific. Science is about numbers, clear measurements.
This month we’re offering just the resource to respond to claims like these, Roger Pielke Jr.’s The Rightful Place of Science: Disasters and Climate Change. I hope you’ll get it. We’ll send it free as our thanks for a donation of any size, while supplies last—just click “Donate,” make your donation of any size, and request it, mentioning Promo Code 1911.
Featured photo by frank mckenna on Unsplash.
E. Calvin Beisner says
A marine geologist who read this article replied to me helpfully by email:
“Your statement that sea level has been rising for thousands of years is not exactly correct. There have been reversals at least since 1500, twice. The oldest sea level records I know of are from the western European coast, from Sweden to Portugal. There are only four records prior to 1800, and the oldest is from Amsterdam. Clearly there was a half-century reversal in the Holocene sea level rise. This is also reflected in Florida maps dating back to 1502. A clear rise occurred between ca. 1710 and 1750, then a drop from 1775 to 1820. Not all of us geologists recognize this fact, but the evidence is quite convincing. The Little Ice Age actually occurred over and over again from the 1300s to the 1800s, each one in the last half of the century, with a warming trend in the early half.”
My thanks to him for the clarification. My point wasn’t that the rise had been uninterrupted but that it’s been the long-term (technically secular–from start to end of a given period) trend. I should have made that explicit.