Just when I thought things couldn’t get much more depressing as far as the melting of the Greenland ice was concerned, my Twitter feed gave me this from Greenland guru Professor Jason Box @climate_ice:
The corresponding headline in a BBC article of 14. September by Jonathan Amos, which includes an interview with Box from the Geological Survey of Denmark and Greenland (GEUS): Climate change: Warmth shatters section of Greenland ice shelf
The giant chunk of ice that has broken away from what is described as the “Arctic’s largest remaining ice shelf” is at 79N, or Nioghalvfjerdsfjorden in north-east Greenland. It is just the latest in a string of – forgive me – shattering developments on and about the “ice island” this summer following hard on the heels of the scorching summer of 2019.
“The atmosphere in this region has warmed by about 3C since 1980,” Dr Jenny Turton told BBC News. “And in 2019 and 2020, it saw record summer temperatures.”
Turton is a polar researcher at Friedrich-Alexander University in Germany
Melting from above and below
The ice which has broken away is Spalte Glacier, an offshoot of “the floating front end of the Northeast Greenland Ice Stream”. The Ice Stream drains around fifteen percent of Greenland’s interior ice sheet. Where the ice stream flows off the massive inland ice sheet and into the ocean, it becomes a floating platform. Higher atmospheric temperatures this year and last year have melted the ice from above, leaving melt ponds on top of it and seeping into crevasses. At the same time warmer sea temperatures are melting the shelf ice from beneath.
“79N became ‘the largest remaining Arctic ice shelf’ only fairly recently, after the Petermann Glacier in northwest Greenland lost a lot of area in 2020 and 2010,” Box told the BBC.
“What makes 79N so important is the way it’s attached to the interior ice sheet, and that means that one day – if the climate warms as we expect – this region will probably become one of the major centres of action for the deglaciation of Greenland,” he went on.
Not happy reading. I find it hard to be optimistic, considering what has been happening in Greenland these last two summers.
Ice claims life of key scientist
In early August, I was shocked and deeply saddened to hear that Konrad Steffen, one of the most renowned and charismatic Greenland experts, whom I had interviewed and taken advice from in the past, had died when he fell into a crevasse on the ice sheet, not far from the camp where he had been studying the impacts of climate change on the ice sheet for the last 30 years.
The New York Times quoted Ryan R. Neely III, a climate scientist at the University of Leeds who studied under Dr. Steffen, as saying not long ago crevasses in the area where Dr. Steffen was working “were unheard-of,” but that they had begun emerging with the stresses on the ice sheet created by warming.
“In the end,” he said, “it looks like climate change actually claimed him as a victim.”
The same article also notes that the crevasse was “a known hazard”. Whatever the circumstances – for me, the death of Konrad Steffen has taken on a special meaning, as a loss for science, humanity – and as symbol of the danger of climate change.
Understanding the planet: a never-ending story
I first interviewed Konrad Steffen in the autumn of 2012, the year which marked the biggest ever melt to that date of the Greenland ice sheet. At that time, he told me we had never experienced so much melt on the Greenland ice sheet since satellite records began in 1979. The image the Swiss scientist used was of three to four times the volume of all the ice in the alps being lost every years from the Greenland ice sheet into the ocean. That hit home to me, a regular hiker in the Swiss alps.
When I asked him at that time if Greenland had reached a tipping point, he told me “we don’t understand the system well enough to say that”. He told me the scientists would keep on making important discoveries, recognising other developments. “This is an ongoing process. We will be surprised in future as well.”
His colleagues continue his essential work – and the shocks and surprises keep on coming.
Is there no going back?
On August 13, Dynamic ice loss from the Greenland Ice Sheet driven by sustained glacier retreat was published in Communications Earth & Environment volume 1, Article number: 1 (2020) . The study, analysing nearly 40 years of satellite data from Greenland, was given the headline: “Warming Greenland ice sheet passes point of no return”.
The headline understandably grabbed media attention and sparked off a lively debate between scientists in the social media and elsewhere.
Michaela King, a researcher at the Ohio State University’s Byrd Polar and Climate Research Centre, is the lead author of the study. She and her colleagues conclude that Greenland’s glaciers have already shrunk so much that “even if global warming were to stop today, the ice sheet would continue shrinking”. They argue that the Greenland glaciers have passed “a tipping point of sorts, where the snowfall that replenishes the ice sheet each year cannot keep up with the ice that is flowing into the ocean from glaciers.”
Their conclusion is based on monthly satellite data from more than 200 large glaciers draining into the ocean around Greenland. This shows both how much ice breaks off into icebergs or melts from the glaciers into the ocean, and the amount of snowfall which replenishes them from above.
The researchers found that the amount of ice being lost each year started to increase steadily around 2000, so that the glaciers were losing about 500 gigatons each year. Since there was no increase in snowfall at the same time, the ice sheet has been losing ice more rapidly than it is being topped up.
Once in a hundred years
Before 2000, King says the ice sheet would have had more or less a fifty-fifty chance to gain or to lose mass each year. “In the current climate, the ice sheet will gain mass in only one out of every 100 years”, she said. Many of Greenland’s big glaciers are now sitting in deeper water, so that more ice is in contact with ocean water, which is getting warmer and melts it.
Ian Howat, a co-author of the paper, professor of earth sciences at Ohio State, says the dynamics of the whole ice sheet are now in “a constant state of loss. Even if the climate were to stay the same or even get a little colder, the ice sheet would still be losing mass,” he says.
Reuters headlined its news item: ‘Canary in the coalmine’: Greenland ice has shrunk beyond return, study finds. The quote is from Howat:
“Greenland is going to be the canary in the coal mine, and the canary is already pretty much dead at this point”.
Other scientists take issue with the idea that a “point of no return” has been reached. I followed an interesting thread on twitter, involving other renowned experts on the subject.
Harry Zekollari from Delft University of Technology suggests the “point of no return” idea may be “somewhat misleading”, although the study on the whole is “excellent and very important”.
Ruth Mottram, an ice scientist at the Danish Meteorological Institute, welcomes his comments, saying “the Greenland Ice Sheet is not (yet) unavoidably lost, choices we make in terms of greenhouse gas emissions can still change future ice loss patterns.”
The fault of the media?
I am not a glaciologist or a climate scientist, but rather a member of the media which, once again, in the course of the debate, get the blame for a “misleading” message. “In a nutshell: amazing and very important work, but the message out in the media (which authors often don’t have full control of) can be seen as somewhat misleading. The situation for the ice sheet is really bad, but it’s (luckily) not yet a ‘lost cause’”, Zekollari tweeted.
Well, let’s be thankful the media are not controlled by authors. I will never tire of reminding everybody that “the media” consist of a wide spectrum of people and organisations. Some of them are frequently guilty of twisting the science for sensation, gloom and doom. But there are plenty of others who work hard to research, understand, and pass a balanced version of events on to their audience.
In this case, the media quoted appear to me to be reporting in line with the conclusions drawn by the authors of the study, quoted above. The “point of no return” headline, incidentally, is used by The Ohio State University.
Balancing realism and optimism
Be that as it may. I understand the concern that a widespread acceptance that we have reached a point of no return could serve the interests of those who would halt climate action and the switch to renewable energies.
There has to be a balance between telling the deeply unsettling truth and creating panic or resignation.
Lead author Michaela King also wrote a blog post of her own, published on August 18, in which she seems to take this into account.
“As is true for many important components of our climate system, our actions now are determining how the ice sheet behaves decades and even centuries into the future”, King concludes.
Zekollari makes some interesting arguments. He acknowledges that “the ice that discharges into the ocean (calving) and frontal melting are indeed too large to be compensated by the mass gain at the surface. So even if temperatures would stabilize at present-day levels, the ice sheet would lose mass for quite some time”.
But he also notes that once the Greenland glaciers retreat to the extent where they have less contact with the ocean, “the total discharge and frontal melt will decrease”.
Grounds for hope?
I will leave the details to the scientists. There has been enough evidence emerging this summer to confirm that Greenland is losing ice at an unprecedented rate and the consequences for the world as a whole will be significant – to put it mildly.
Sea level rise
A study published in the International Journal of Climatology on August 17 , analysing almost 30 years’ worth of scientific data on the melting of the Greenland Ice Sheet, predicts global sea level rise of at least 10 centimetres by the end of this century if global warming trends continue.
Professor Edward Hanna of the University of Lincoln, UK, led the international team for the study “that quantifies the response of the Greenland Ice Sheet to climate change. The scientists say their worrying estimates are “conservative”.
The team analysed Greenland surface air temperature data for the last three decades through to 2019 and combined it with computer models of ice-sheet mass balance for 1972 to 2018. They worked out that under a “business as usual” emissions scenario, Greenland is likely to warm by a staggering 4 to 6.6 degrees Celsius by the year 2100.
“These recent and projected future Greenland warmings are considerably greater than global temperature changes for equivalent time periods, reflecting a high sensitivity of the polar regions to climate change”, they conclude.
They calculated that the temperature rises would result in a 10 to 12.5 centimetre increase in global sea level rise by 2100 arising from increased Greenland ice melt and surface mass loss.
The team also explored the relation between Greenland air temperature changes and what is known as “atmospheric high pressure blocking”. As I discussed in an earlier post, this phenomenon strengthened in spring and summer in recent decades and played a crucial role in the dramatic Greenland melt in the summer of 2019. Hanna and his colleagues stress that this needs to be better considered in computer climate models for the future.
2019: record-breaking ice loss
If there was still any doubt left in our mind, a study published in Communications Earth and Environment on August 20, using data from NASA’s Grace satellites, confirmed that the Greenland ice sheet lost a record amount of ice in 2019.
It shrank by 532 billion tonnes. If you find that hard to imagine, Damian Carrington in the Guardian, says it would have filled seven Olympic-sized swimming pools per second. Vincent Wood in the Independent said Greenland lost enough ice to cover the US state of California in more than four feet of water in 2019. I’ll let you decide which image moves you more.
The researchers described the loss as “shocking and depressing in terms of the numbers” and said it was likely to be “the biggest in centuries or even millennia”. Ingo Sasgen of the Alfred Wegener Institute in Bremerhaven Germany, who led the analysis, also said it was not very surprising, “because we had other strong melt years in 2010 and 2012, and I expect we will see more and more.”
This time, though, the researchers said it was not certain that the sheet has passed the point of no return and that cutting carbon emissions would slow the melting, which will happen over centuries.
They attribute the extreme ice loss to the “blocking patterns” mentioned above and in my earlier post, with warm air sitting over Greenland for long periods. These seem set to increase in our warming world.
You might wonder whether cold years might compensate for the hot ones. But the researchers found that in 2017 and 2018, although there was an unusually low loss of ice because these blocking patterns were reversed, the sheet still lost ice.
“If we reduce CO2, we will reduce Arctic warming and we will therefore also reduce the sea level rise contribution from the Greenland ice sheet,” said lead author Sasgen.
“So even though it might eventually disappear in large part, it happens much slower, which would be better as it would allow more time for the 600 million people living near coasts to move away.”
On track for the worst-case scenario
On the impact on sea levels, Ruth Mottram, Tom Slater and Anna Hogg also released a paper on August 31, which compare the ice sheet losses both in Greenland and Antarctica and their impact on sea level to the predictions made by the IPCC Fifth Assessment Report (AR5): Ice sheet losses track high-end sea-level rise projections.
(You can read the article shared here.)
The title says it all. We are moving along a trajectory which would lead to sea level rise in line with the most extreme predictions of that 2013 report.
“During 2007- 2017 satellite observations show total ice-sheet losses increased the global sea level by 12.3mm +- 2.3 mm and track closest to the AR5 upper range (13.7-14.1mm for all emissions pathways), the scientists find.They say the average rate of sea level rise is 45 percent above central prediction, and closes to the upper range.
“These upper estimates predict an additional 145 -230 mm of SLR (sea level rise) from the ice sheets ABOVE the central predictions by 2100. SLR of 150mm would double storm-related flooding frequency across the west coasts of North America and Europe and in many of the world’s largest coastal cities. Ice sheet losses at the upper end of the AR5 predictions would expose 44-66 million people to annual coastal flooding worldwide.”
They also note that the AR5 projections do not cover some important variables, suggesting the situation could get even worse. (For Greenland, they mention changes in atmospheric-circulation-induced extreme melting and substantial variability in meltwater runoff are not captured in the predictions. The role of clouds is another complicating factor.)
Where do we go from here?
So all in all, from this Iceblogger’s point of view, 2020 has been a pretty disastrous summer.
While the Covid19 pandemic has demonstrated our vulnerability, with life disrupted the world over, it has shifted attention away from the crisis of our times with such potentially disastrous implications for coming generations and the future of the planet we live on.
So have we reached a point of no return?
I have just watched a short video on the Greenland Ice Sheet group on Facebook. It was made for the Unu Mondo expedition, a “4 months sailing expedition into the Arctic aimed to gather scientific data and testimonies from local communities to better anticipate climate change and promote concrete actions”. In the film, glaciologist Jason Box, quoted earlier in this post, explains the extent of the crisis and the effects of climate warming on the Greenland ice sheet, the largest body of frozen water in the northern hemisphere, what we once thought of as permanent frozenness.
The figures he gives are staggering. And shivers run down my spine when he says he cannot imagine any scenario that would cool the planet.
There is no point in glossing over it. Humankind has gone too far to reverse much of the damage we have put in motion. The task for us communicators – the media-savvy scientists, the journalists, the bloggers, the educators – is to get the message across that this is not a carte blanche to carry on with business as usual. We have to reduce greenhouse gas emissions and move very rapidly towards a carbon-neutral world to avert even worse consequences, protect the nature we are a part of and keep the planet liveable for future generations.