Greenland is the largest island in the world and has the largest ice cap in the Northern Hemisphere. If that ice melts, the sea will rise more than 7 meters.
But it’s not going to happen, is it? Well, not soon, but understanding how much of a sheet of ice can melt is an important and urgent question that scientists are trying to use sophisticated statistical models of how an ice sheet interacts with the rest of the climate system. .
The problem is that the models are not so good at reproducing recent observations and are limited by our poor knowledge of detailed topography of subglacial terrain and phages flowing over ice.
One way around this problem is to see how the ice sheet has reacted to weather changes in the past and compare it with future sample estimates for similar changes in temperature. Now in a new study published in the journal and I colleagues have done exactly the same Nature Communications.
We looked at three of Greenland’s largest glaciers and used historical historical aerial photographs with criteria taken directly from scientists over the years to reconstruct how the amount of these glaciers changed between 1880 and 2012.
The approach is based on the idea that the past can help inform the future not only in science but in all aspects of life.
But like other “classes” of history, future climate and earth systems will not be carbon copies of the past. However, if we know how sensitive an ice sheet is to temperature changes in a century, it can provide useful guidance on how it will respond in the next century.
We found that three large glaciers were responsible for the 8.1 mm rise in sea level, which is about 15 percent of the contribution of ice sheets.
During the period of our study, the global sea level was about 20 cm. Has increased, which is about the height of the A5 booklet and from it, the width of the finger is almost due to the melting of ice from those three Greenland glaciers.
Melting as usual
So what does that tell us about the future behavior of the ice sheet? In 2013, a modeling study by Fa Fa Zick and colleagues also looked at similar “big three” glaciers (Jacobswan Isbre in the west of the island to the east and Hellham and Kangarlusuak in the east) and estimated how they would react in different scenarios of the future. .
The most extreme in these circumstances is RCP.5. called and assumes that economic growth will remain the same in the 21st century, resulting in a global average global temperature of about 7.5C. ).
This scenario is sometimes referred to as Business General (BAU), and there is active discussion among meteorologists about how rational RCP8.5 is. It is interesting to note, however, that the U.S. According to a recent study by a group of scientists, at least until 2050 it may be the most appropriate scenario.
Due to something called polar amplification, the Arctic will probably have temperatures more than twice the global average, climate models RCP8 in the extreme view over Greenland. about 3 in over. 8˚s.
Despite this dramatic and alarming rise in temperature, Fejeh’s modeling study estimates that the “big three” will contribute between 9 and 15 mm to sea level rise by 2100, slightly less than what we gained from 1.5 degree centimeter warming in the 20th century. Is higher. . How could that be?
Our conclusion is that the models have drawbacks, including the latest and sophisticated ones available, which are used to assess how the entire ice sheet will respond to climate change in the next century.
While our results suggest it is stronger, these models have a relatively weak link between climate change and ice melting.
Estimates based on these models are therefore likely to predict how much the ice sheet will be affected. Other lines of evidence support this conclusion.
What does it all mean? If we continue on the path to the very scary RCP 8.5 of rising greenhouse gas emissions, Greenland is likely to start melting ice sheet rates that we have not seen for at least 130,000 years, with sea levels and its dire consequences for millions of people who Live in areas. 
Jonathan Bamber, Professor of Physical Geography at the University of Bristol.
This article is republished from a talk under the Creative Commons license. Read the original article.
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