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Over the millennia, these abrupt changes — which can happen "faster than a political cycle" and certainly within a matter of decades, he said — have at times coincided with the fall of empires.
There's complex science behind how this happens. For purposes of current ice-melt trends, one crux is that glaciers are made of fresh water, which thins the salty seas as it melts into them. Less dense water doesn't sink the way it should, slowing the flow of warmer surface water across the Atlantic.
This affects the weather in the short term while leaving longer-term marks on the oceans: more melting of sea ice, warmer lands and waters at the edges of glaciers, and more melting of the glaciers in turn. This causes rising seas and myriad other effects. Mayewski said one change that has arrived in force in Maine, thanks to our especially fast-warming ocean, is worsening coastal storms.
An abrupt climatic shift — perhaps caused by the collapse of an ice sheet or a pulse of methane from thawing permafrost — might appear in hindsight as a climate tipping point.
This will not look like The Day After Tomorrow. It will be protracted and diffuse, even if only spread over a matter of a few years. It will likely manifest in massive droughts, fires and floods that lead to unprecedented mass migration and increased instability and struggle across the world.
"If you suddenly tell people that 10 years from now, the tipping point occurs and we're toast, nobody's going to do anything," Mayewski said.
Instead, he frames it this way: "These things will occur. They can be moderated dramatically by our behavior, but we also need to be prepared for them, and we need to be planning."
Exchange and empathy
Eco-tourism, like what I did in Iceland last week, of course has serious environmental impacts of its own. The air travel industry, if it were a country, would be the world's sixth-biggest emitter.
There was an acute irony in staring down the visible signs of rapid human-caused climate change from amid a carbon-fueled throng of tourists, even in the most renewable-powered nation on Earth.
But Mayewski said he's all for eco-tourism done responsibly. It shows people the power and scale of these changes firsthand, he said, and that helps their family and friends appreciate it too.
I watched this happen for my mom in Iceland: As she realized just how quickly those glaciers were melting and understood humans' effect on that speed, she was horrified. She's already very climate conscious, and yet the firsthand experience of something so clear-cut made a harsh impression.
“It's critical for people to think beyond their own small borders and worlds," Mayewski said. "The more exchange we have — the more we can empathize with situations which we are fortunate enough not to experience — the better off we are.”
ICYMI
Catch up on the latest installments in Climate Monitor co-author and Monitor editor Kate Cough's series on the future of Maine's salt marshes, Sinking in Saltwater, and stay tuned for more. Plus: Derrick Z. Jackson went to see the puffins on Seal Island.
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