Today we have three stories that are absolutely horrifying in juxtaposition.
The first is a paper that came out a couple of days ago in Nature, describing a study by Jade Bowling (of Lancaster University) et al. It is an analysis of a strange and sudden change in the topography of the Greenland Ice Sheet that happened in 2014 -- a two-square-kilometer part of the sheet dropped by as much as eighty-five meters. The question, of course, is what happened to all the ice that used to be underneath it. And what Bowling et al. found was that it had melted -- that the underside of the Greenland Ice Sheet is riddled with subglacial lakes and rivers. In this case, downstream of the collapsed region, a flood burst through the surface, and within ten days ninety million cubic meters of fresh water gushed out as the cavity emptied.
We usually think of the melting of the polar ice sheets as a gradual process, something like the way ice cubes slowly melt in your glass of tea in summer. But what this study shows is that the process proceeds quietly -- until it doesn't. The tipping point between a gentle trickle and a massive flood can occur suddenly, and be due to factors that are largely out of sight.
The second came out in the same issue of Nature, and has to do with a study of the paleoclimate by a team led by Pedro DiNezio of Colorado University - Boulder. DiNezio and his collaborators looked at the Atlantic Meridional Overturning Circulation (AMOC), sometimes called the "Atlantic Conveyor." The AMOC is an enormous ocean current, of which the Gulf Stream is only a part, moving a greater volume of water per second than all of the rivers of the world put together. It is driven by the combined effects of evaporation (making the water saltier) and cooling as the current flows northward; both of these result in the water becoming denser, and south of Iceland it becomes dense enough to sink. This draws more warm water northward -- and is why Ireland and the United Kingdom, which are on the same latitude as Alberta, have mild climates.
But freshwater intrusion, like the one the prior study considered, lowers the density of the surface water, eventually making it too fresh to sink. This can slow down -- or halt entirely -- the AMOC.
The focus of the effects has usually been on northeastern North America and northwestern Europe, where that heat transfer slowdown would be expected to trigger a dramatic cooling similar to the sudden crash that initiated the Younger Dryas 12,900 years ago, during which a warming climate was plunged back into the freezer for over a thousand years. But what the DiNezio et al. study considered was what happens to all that excess heat. Just because we here in upstate New York would probably be freezing our asses off doesn't mean the rest of the world would be. The heat energy, of course, doesn't just go away.
And what they found is that when the AMOC slows down, that heat remains in the tropics -- triggering a spike in temperature and a drop in rainfall near the equator. "This is bad news, because we have these very important ecosystems in the Amazon," said DiNezio. "The Amazon rainforest contains almost two years of global carbon emissions, making it a major carbon sink on Earth. Drought in this region could release vast amounts of carbon back into the atmosphere, forming a vicious loop that could make climate change worse."
But of course, no story about climate change would be complete without some breaking news describing how the Trump administration is determined to make it worse. Lee Zeldin, head of the Environmental Protection Agency (which should have its name changed to the Big Oil Protection Agency, because under his leadership they couldn't give a flying rat's ass about protecting the environment), has just announced the overturning of a 2009 declaration stating that carbon dioxide and other greenhouse gases endanger human health and welfare.
His justification? What do you think it was?
"It cost Americans a lot of money," Zeldin said.
The declaration was the foundation of climate change regulation in this country, and the impetus for rules limiting emissions from cars, airplanes, and power plants. If the "endangerment finding," as the declaration is called, is overturned. it gives corporations carte blanche to ignore previous guidelines and mandates.
Zeldin, of course, thinks this is just hunky-dory. "This will be the largest deregulatory action in the history of America," he crowed.
Because short-term profit is apparently more in need of attention than the long-term habitability of the planet.
I wish I had a hopeful note to end on, but I don't. The whole thing puts me in mind of a comment from a student in my Environmental Science class, maybe fifteen years ago. The question I put to them was, "At what point do you think that the majority of Americans will be motivated to address climate change in a meaningful way?"
Her answer was, "It won't happen until average Americans are directly and harshly impacted by it. When there's no food on the shelves in the grocery stores. When the rivers dry up. When the sea level rises enough to flood major coastal cities. Until then, it's easier to pretend nothing's wrong."
Another student, aghast, said, "But won't it be too late at that point?"
She responded simply, "Of course it will."
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