New science predicts a “chaotic climate” with bigger changes in temperatures year to year. Dr. Nicholas Golledge told Scientific American: “This unpredictability is going to prove extremely disruptive for all of us, and will make adaptation and planning much more difficult”. And the driver for all of that comes from the furthest ends of the Earth. Yes, we are going to talk about ice melt on Antarctica and Greenland, and yes this will affect you. There is also a small sliver of possibly better news. The most apocalyptic predictions for sea level rise may not happen.
Golledge is lead author of “Global environmental consequences of 21st century ice sheet melt”, just published in Nature, and 69 other peer-reviewed scientific papers. Educated in Scotland, Associate Professor Nick Golledge is currently with the Antarctic Research Centre at Victoria University of Wellington New Zealand.
Show by Radio Ecoshock, reposted under CC License. Episode details at https://www.ecoshock.org/2019/02/out-of-the-smog-into-the-sea.html
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TRANSCRIPT EXCERPT
This new paper says:
“It is likely that global temperatures in the year 2100 will exceed the 2°C target set by the Paris Agreement, because simulations indicate a likely increase of 2.6 to 4°C above pre-industrial baseline temperatures even if the pledges made by signatory countries of the Paris Agreement are honoured.”
Plus, when governments met in Katowice Poland in December 2018, the projections given to them by international scientists did not really include the impacts of ice-sheet discharge.
We need to separate two key impacts from ice melt in Greenland and Antarctica. One issue is changes in ocean currents that will destabilize weather, especially in the Northern Hemisphere. People in Eastern North America and Northern Europe are not going to like that news.
SEA LEVEL RISE—LATEST ESTIMATES
On Radio Ecoshock, at least a dozen scientists said sea level rise, not heat, will be the great game-changer emerging out a shifting climate. It’s about disappearing port cities, millions of people displaced from flooded agricultural deltas, and a lot more. But predictions for sea level rise by 2100 have been all over the place, running from a low of just 30 centimeters to as much as 7 meters. Nick talks about why there is such a difference, all coming from good scientists.
"Predictions for sea-level rise this century due to melt from Antarctica range from zero to more than one meter. The highest predictions are driven by the controversial marine ice-cliff instability (MICI) hypothesis, which assumes that coastal ice cliffs can rapidly collapse after ice shelves disintegrate, as a result of surface and sub-shelf melting caused by global warming.
"But MICI has not been observed in the modern era and it remains unclear whether it is required to reproduce sea-level variations in the geological past."
The lowest estimate of .5 meters of sea level rise by 2100 given by Gollege’s results clashes with the figure of several meters of sea level rise published by Dr. James Hansen’s team in 2016: “Ice melt, sea level rise and superstorms”. I’m doubtful about the lower estimate given by Golledge and team. I worry low estimates may lull people into complacency instead of adaptation.
The sea is not really level, and sea-level rise will not be evenly distributed. As the ice sheets melt, higher waters pile up in some places. Close to the glaciers themselves, sea levels are expected to go down, because the mass of all that ice on Greenland and Antarctica attracted so much water by the force of gravity. As that mass rapidly declines, that sea water will go elsewhere in the world.
ICE MELT = CLIMATE CHAOS
The first new paper with Nick as lead author says: “Perhaps more immediately impactful than gradual warming is the possibility of enhanced interannual temperature variability, which would result in more widespread or more frequent terrestrial and marine heat waves.”
How could the process of melting ice at the poles increase the size or frequency of heat waves in the faraway lands where we live? Nick says that is because of the mechanics of the way ice melts as it contacts warmer sea waters. One year something big can break off, like the Larsen B ice shelf collapse in 2002. That may change the weather slightly around the world. But the next year, there may be far less ice movement into the sea. So to some degree, our weather patterns may go back and forth with the irregular procession of glaciers into the sea.
ATLANTIC OCEAN OVERTURNING CIRCULATION
Many in the scientific community have been saying nothing significant will happen to the North Atlantic Overturning Circulation for centuries to come. But Golledge stirs it up, suggesting we WILL see noticeable changes to those warming currents, even during this century.
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