Greenland has more than two trillion tonnes of water, locked in a huge ice blanket that stifles 80% of its land. If they were to disappear, it would have led to an increase in the sea level around the world by seven meters on average, leaving very low shores and sunken islands.
And as the rise in Arctic temperatures has led to the sea ice that covers much of the ocean of the region, to withdraw even more, scientists nervously study the Greenland ice sheet to see how it is affected.
They fear that without the insulating effect of sea ice – along with its ability to reflect summer sunlight – Greenland could suffer accelerated meltdowns in the coming decades. In fact, with global temperatures, which are currently warmest in over 11,000 years, there are fears that the world may have engaged in melting in Greenland in the coming decades.
Now studies that use sophisticated computer models to simulate the link between the Arctic and the ice in Greenland suggest that this is not the case.
Researchers working on the Ice2Ice project have shown that changes in Greenland's sea ice and ice sheet appear to be largely independent of one another. Sea ice is prone to temperature changes in the water layers in the ocean below it, while most of Greenland responds to the rise in atmospheric temperature.
The simulation of Greenland's ice sheet and climate change, showing that its melting is largely independent of sea ice. Video credits – DMI, CSC (J. Hokkanen, visualization)
The intention is that, although Arctic ice is declining, Greenland's ice can remain for centuries. This implies that efforts to reduce greenhouse gas emissions and to limit global warming below 2 ° C above pre-industrial levels, as set out in the Paris Climate Change Agreement, can allow the world to prevent the melting, which would lead to a catastrophic level of sea level.
"This means we do not have to worry about any side effects of losing sea ice on the surface melting in Greenland, which is due to the greenhouse effect," said Professor Jens Hesselbjerg Christensen, Climate Change at the Niels Bohr Institute in Copenhagen, Denmark and one of the leading coordinators of the Ice2Ice project.
"Still, the loss of Arctic sea ice is still worrying because it has a major impact on the ecosystems in the region."
The Ice2Ice project restores the way ice-ice in the Arctic and the ice of Greenland has responded to climate change in the past by analyzing Greenland's ice cores and Arctic Ocean sediments. They used this information to build a simulation of what could happen if the world still warmed up.
"We conducted an experiment in which we had 15 ° C global warming, which is too high to make the entire sea ice disappear," said Professor Hesselberg Christensen. "Even this, the Greenland reaction only seems to be due to the overall strong greenhouse effect that has remained stable for hundreds of years and we have not been able to see much of the impact of losing sea ice." He said the ice sheet had begun to change its shape in a few hundred years.
While the simulation of such extreme warming may seem unrealistic, some parts of the Arctic already experience a sharp change in temperature at a local level that can mimic this in the coming decades.
"If you look at Svalbard (on the Arctic Ocean), over the last 40 years, we have witnessed very large temperature changes, something like 2 ° C per decade," said Professor Hesselberg Christensen. "If it lasts more than 100 years, then warming (locally) will be very strong."
While global temperatures are expected to have increased by about 1 ° C compared to pre-industrial times, this is an average increase worldwide. Some areas will get more warmth – like the Arctic – while others will not.
"One of the problems we have is that the Arctic is still not well understood."
Professor Gary Petersen, Center for Resilience in Stockholm, Sweden
This has led many people to think that the Arctic is something like a canary in the coal mine for what may be in the store as the world continues to warm up. Stockholm's Sustainability Center in Sweden has recently identified 19 regime shifts, which are considered as markers of how climate change is transforming the Arctic.
He found that there are already data that 15 of these regime shifts are taking place in the Arctic, as weather conditions cause irreversible changes in the vegetation of drought and ocean ecosystems.
"The Arctic is the forerunner of climate change around the world, as it generally warms twice as fast as the world average," said Professor Gary Peterson, an ecologist at the Stockholm Center for Sustainability. "There is growing concern about how sea ice loss is changing in global climate patterns."
A recent publication, published last year in Nature, found evidence that Arctic ice loss may affect patterns of precipitation around the world, leading to droughts and fires in places like California, which this year saw devastating flames,
"One of the problems we have is that the Arctic is still not well understood," said Professor Peterson. "The Arctic has relatively little observation compared to other parts of the world, so we will probably see more surprises as the Arctic continues to change.
Most of our knowledge of the changes that are currently taking place in the Arctic come from satellite images that show declines in summer ice in the last 40 years. Unfortunately, we really understand whether this is due to mankind's influence on climate or natural variations in the environment needs data that goes back to the past.
The IceDynamO project is attempting to build a high-resolution reconstruction of the Arctic Ocean seabed off the coast of the northern Greenland ice sheet. Using the information stored in the sediment at the bottom of the ocean, project researchers have linked how sea ice varies over the last few millennia and how the ocean and weather conditions may have affected it.
"If we can see what has happened over the past 2000 years, we can see what natural variations in sea ice are before people start to influence it," said Dr. Teodóra Pados, a geoscientist at the Aarhus University in Denmark, project researcher. – We need to understand what is the natural diversity of sea ice in the recent past and what has caused it.
Although the project began only earlier this year, the results should help scientists' attempts to build patterns on how the Arctic is likely to change over the coming years. The fate of the region can have profound consequences not only for those living there but also elsewhere in the world.
"(The variation in) sea ice influences large-scale climatic phenomena that affect elsewhere in the world," said Dr. Patos. "A recent study has shown that it may, for example, influence weather in Europe's mid-range latitudes and is also known to affect the deep water transport belt that transports water around the world (the system) is very complex and we still do not know what will be the effect if we lose sea ice.
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