Environment

Weird weather pushes Greenland to worst ice loss on record

Weird weather pushes Greenland...
The Greenland ice sheet, which lost a record-breaking amount of ice in 2019
The Greenland ice sheet, which lost a record-breaking amount of ice in 2019
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The Greenland ice sheet, which lost a record-breaking amount of ice in 2019
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The Greenland ice sheet, which lost a record-breaking amount of ice in 2019
Charts highlighting anomalies in Greenland in 2019
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Charts highlighting anomalies in Greenland in 2019
The average pressure over Greenland in 2019 was much higher than usual
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The average pressure over Greenland in 2019 was much higher than usual
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A new study has calculated that the Greenland ice sheet lost hundreds of billions of tons of ice last year, marking the biggest drop in its ice mass since records began in 1948. And warm weather alone wasn’t to blame – the team found that unusual pressure patterns had the most devastating impact.

The study, led by researchers from Columbia University’s Lamont-Doherty Earth Observatory, analyzed summer changes in the Greenland ice sheet by examining satellite data, climate models, and measurements taken from the ground.

And the results weren’t pretty. Overall, the team estimated that as much as 600 billion tons of Greenland’s ice was lost in 2019. That means the ice sheet’s surface mass balance plunged about 320 billion tons below the annual average for 1981 to 2010.

When conditions are stable, natural ice loss is offset by gains from snowfall. But in this case, only 50 billion tons were gained in 2019, barely making a dent in the record-breaking loss.

The reason for this devastating year isn’t as clear-cut as just rising temperatures. The previous worst year on record was 2012, when ice mass dipped 310 billion tons below the average. But temperatures were warmer in 2012 than 2019, so the team figured there must be other factors at play.

On closer examination, the researchers discovered that high-pressure conditions lingered over Greenland for much longer than usual last year. This triggered several mechanisms that all added up to increased ice loss.

These conditions prevented clouds forming over southern Greenland, which let in more sunlight, melting more surface ice. At the same time, fewer clouds meant less snowfall so less ice was being replenished. Snow’s brightness also helps reflect some sunlight away, and without it more ice absorbed the heat, accelerating melting.

Other parts of the country didn’t fare much better. The high-pressure conditions over the south pulled warmer air into the north, where they formed more clouds. Unfortunately, these weren’t the snow-producing kind – instead, they just trapped heat and increased melting further.

Charts highlighting anomalies in Greenland in 2019
Charts highlighting anomalies in Greenland in 2019

The team says a similar pattern was likely at play in 2012, and with the climate continuing to change at such a rapid pace, these kinds of conditions are probably going to become the new normal.

Unfortunately, the researchers say that current climate models don’t account for this kind of mechanism. That means that future melting may be twice as bad as is currently predicted.

It looks like Greenland’s weird weather is just another symptom of climate change, which began making itself even more apparent in 2019. The year was one of the warmest on record, with July the individual hottest month humans have ever recorded. Ocean temperatures reached new heights, and Australia saw its hottest year ever, punctuated with devastating bushfires.

The new study was published in the journal The Cryosphere.

Source: Columbia University

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7 comments
Signguy
So we're coming out of the ice phase BACK INTO a warming phase...like they used to be.
bwana4swahili
Sounds like it won't be long before Greenland will be a nice place to holiday!?
ljaques
Yeah, buddy. And if you think that's bad, you ought to see what happens in SUMMER!
JeffK
In twenty or thirty years they'll be producing some fine Riesling, hope I'm still around to enjoy it!
aksdad
From the study: "The average mass loss values in Greenland over the extended time period (April 2002-September 2019) agree well... Over that time period, the acceleration in mass loss in Greenland is not significant." Also this: "In Greenland, the ice sheet experienced back to back cold summers in 2017 and 2018, but 2019 saw a return of warm conditions, with a high summer loss and one of the lowest SMB on record." And this: "The fluctuations in mass loss are dominated by the interannual variability in SMB, but the long term signal remains a widespread, steady mass loss from all corners of the ice sheet". And lastly, this important bit: "Key factors for the exceptional loss of 2019 were the persistence of anticyclonic conditions over the summer, promoting high snow and ice melt,combined with low precipitation of snow in the previous winter." Nowhere in the study did the authors make any claim related to climate change. None. This bit in the article above "with the climate continuing to change at such a rapid pace, these kinds of conditions are probably going to become the new normal" is the author's opinion, not supported by anything in the study. And this claim "That means that future melting may be twice as bad as is currently predicted" is also the author's opinion, not supported by anything in the study. Mr. Irving, could you provide us with evidence to support you opinion? You seem to be reading a lot into one annual anomaly dominated by natural variation while ignoring the long term trend which shows general but modest warming (over the last 40 years, from global satellite measurements, about 1.3° C per century). Perhaps sticking to science instead of hyperbole would better inform the readers.
Michael Irving
@aksdad: From the press release, “Because climate models that project the future melting of the Greenland ice sheet do not currently account for these atmospheric patterns, they may be underestimating future melting by about half, said lead author Marco Tedesco from Columbia University’s Lamont-Doherty Earth Observatory.” He goes on to say “simulations of future impacts are very likely underestimating the mass loss due to climate change.”
aksdad
Thank you, Mr. Irving, for pointing out that Marco Tedesco made the claim that "they may be underestimating future melting by about half". I was wrong to say that you inserted that yourself. Tedesco's speculation, however, is not based on data and it's exactly in the wrong direction. The climate models project warming that is 200% to 370% higher than actually measured. RCP8.5 assumes essentially no global mitigation of carbon dioxide levels (which is exactly what's happening) and predicts a warming trend of 2.6 to 4.8° C (mean of 3.7° C) by 2100. And sea level rise of 0.45 to 0.82 meters. It's the scenario most referenced in all the studies related to climate change. The measured average global warming trend over the last 40 years (by satellite) is 1.3° C per century (from UAH; RSS puts it slightly higher but they haven't corrected for orbital drift like UAH has). Average rate of sea level rise since 1993 is ~0.2 to 0.31 meters (measured by tide gauges and satellites, respectively). The measured rate of warming and sea level rise puts us squarely in the RCP2.6 scenario, the one that supposedly requires drastic, global, coordinated action to reduce CO2 emissions so that they peak and decline starting this decade, even though nations are doing very little to curb emissions and certainly nothing to counter the rapidly growing emissions from China and India. The exaggeration of climate models suggests that the future rate of Greenland glacier melt predicted by computer models would be much less, not more, than predicted; contrary to Tedesco's musings.