Hey, we haven’t checked in on the Greenland in a while, let’s see what’s hap… Oh. Oh no.
New research published on Wednesday in Nature shows the Greenland ice sheet is already pushing the boundaries of mass loss seen over the past 12,000 years. Even under the best-case climate scenario, where humanity rapidly draws down emissions starting ASAP, the ice sheet is set to hit unprecedented levels of loss over the course of the century.
The Greenland ice sheet has been really beat up in recent years. Wildfire smoke, dust, heat waves, and even sunny skies have all contributed to massive annual meltdowns. It’s losing ice at a quickening rate, and the new study adds up those year-over-year losses and puts them in the context of both the past and the future. To do that, the researchers used computer simulations of the past and then compared them to ice core samples and other data based on the geology around Greenland. Those geologic and ice core proxies allowed the researchers to reconstruct growth and loss of ice over the past 12,000 years for an area of western Greenland that mirrors the rest of the ice sheet. The timeframe is significant, since it represents the end of the Ice Age and a period known as the Holocene.
Over that time, natural fluctuations in the climate have affected the ice sheet, including a big period of loss roughly 8,000 years ago, when an estimated 6,000 gigatons of ice melted into the sea each century. That’s 6 trillion tons of ice, which I could try to find a comparison for, but let’s just call it an assload of ice. Since then, there have been much smaller perturbations in the ice sheet. That is, until now.
Humans have started to overwhelm that system by pumping carbon pollution into the atmosphere. The planet has warmed by about 1.8 degrees Fahrenheit (1 degree Celsius) since the late 19th century, but the warming has become more acute in recent decades. That’s led to all sorts of problems, including more rapid declines in the mass of Greenland ice sheet. The new findings suggest if the rate of loss over the past two decades stayed the same throughout this century, Greenland would shed 6,100 gigatons of ice, or slightly more than an assload.
Unfortunately, climate change has other plans. The study’s future modelling shows that an extremely optimistic climate scenario, where the world starts reducing emissions right now and zeroes them out by century’s end, would still result in a minimum of 8,800 gigatons of ice melting this century. If the world goes wild and keeps burning carbon with reckless abandon this century, up to 35,900 gigatons (nearly 6 assloads) of ice could end up in the sea. In a cheerily titled commentary accompanying the piece, “The Worst is Yet to Come for the Greenland Ice Sheet,” University of Alaska, Fairbanks ice researcher Andy Aschwanden notes that it’s “increasingly certain that we are about to experience unprecedented rates of ice loss from Greenland.”
That has huge ramifications for coastal communities as well as ecosystems. The melting ice sheet is responsible for roughly 30% of all sea level rise, and its contribution is set to rise this century on top of increasingly unstable ice in Antarctica. The findings show that, regardless of action humanity takes to curb emissions, countries will also need to adapt to a world with higher seas. That could mean building out natural or manmade flood defences or retreating from the coast altogether.
At the same time, all the ice melt from Greenland is leading to a pocket of cold, fresher water sitting off the coast. That’s slowing down the current that runs up the East Coast and traverses from there to the other side of the Atlantic. How that impacts the ecosystem there as well as ocean circulation elsewhere is still an area of active but disconcerting research. Scientists will also continue to scrutinise the fate of the ice sheet itself under different emissions scenarios, and I just want to put it out there that world leaders should work to ensure we don’t get a chance to check their work on the high-end one.