Greenland Ice Has Passed the Tipping Point

How sea level rise will make rivers catastrophically change course and how to make veg attractive: It’s time for the Haaretz climate change briefs!

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Greenland glaciers calving
Greenland glaciers calvingCredit: Michalea King

Greenland ice has reached the point of no return, scientists warned last week. What does that mean? Under normal conditions, ice flows into the sea during the short summer, and is replenished by snow during the rest of the year. Now the ice sheet has shrunk so much that even if global warming were to stop in its tracks, which it isn’t about to do – the ice sheet can’t get enough snow to recover, scientists explain in Nature Communications Earth and Environment.

Not there yet? “The ice that’s discharging into the ocean is far surpassing the snow that’s accumulating on the surface of the ice sheet,” explains lead author Michalea King, of Ohio State University. The melt rate surged in about 2000: In the current climate, the ice sheet will gain mass in only one out of every 100 years, Science Daily elaborates.

Sea-level rise to drive catastrophic river course changes

Naturally, as the Greenland and other ice sheets melt, seas are rising. One consequence one doesn’t immediately think about is river avulsion, which means they change course, scientists at the California Institute of Technology warned in PNAS. Why would rivers do that? “Avulsions are the earthquakes of rivers,” says Prof. Michael Lamb, a geologist at the University of California, Santa Barbara. “They are sudden and sometimes catastrophic natural events that occur with statistical regularity, shifting the direction of major rivers.” How? When the sea rises, rivers deposit more sediment into their own channel, raising the riverbed relative to the neighboring land, making the river unstable. Ta-da! And if the sea level rises faster than rivers deposit sediment, the zone of deposition and avulsion will shift upstream, the team warns.

Satellite view of a river avulsion, whereby the river abruptly and catastrophically changed its course to the ocean: East Aceh, SumatraCredit: Sentinel 2/ Vamsi Ganti/ Sam Bro

Why turtle dove populations are down 95%

Climate change and habitat loss were expected to affect migratory birds. Well, they do, according to a study led by Durham University, U.K., as mapped for 100 species in the journal of Diversity and Distributions. In the U.K., major declines have been observed in many bird species that migrate from wintering in Africa to breed the summer. "For example, the turtle dove has declined by 95 percent between 1992-2017, and the nightingale has declined by 56 percent between 1995-2018,” the team writes. The researchers estimate that the combined effects of changes in climate and land cover in Europe and Africa are responsible for 40 percent of the variation in avian population trends; that in turn implies that habitat quality also has a substantial impact.

Swallows migrate between South Africa and Europe every yearCredit: Philip Stephens

Yes, do restore degraded forests, study says

Here is an upside story. Deforestation is massively adding carbon to the atmosphere and transforming degraded forest into cropland isn’t helpful. Now an international study published in Science says restoring degraded forests is much better, carbon-wise, than letting them rebound naturally. Restoration lifts carbon storage recovery by more than 50 percent compared to natural regeneration, researchers write in Science. A degraded forest is not a lost cause.

Seeds being grown for large-scale forest restoration effortsCredit: Michael O'Brien / SEARRP

Way found to make people eat vegetables

We know that livestock farming is inhumane and bad for the planet, but getting people to eschew burgers for beans is tricky. A vast study at the cafeterias of two Cambridge colleges showed that it’s all about the location, location, location of the vegetarian options. Analyzing data from a whopping 105,143 meal selections over two years, alternating the placement of meat and veg dishes weekly and monthly – they found that placing veg options before meat did nothing at one college but at the other, sales of plant-based dishes shot up 40 percent, according to the monthly analysis.

What – did they put the meat in the basement? No: They put the veg first and the meat an extra distance away. One meter at one college didn’t do the trick but an extra 1.81 meters at the second college did, according to a report in Nature Food. Holy cow, people are lazy. Last year the same team showed that adding an extra veg option depressed meat sales.

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