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Greenland is the largest island in the world and has the largest mass of ice in the Northern Hemisphere. When all that ice has melted, the sea will rise over 7 meters.
But it won’t happen, will it? Well, not anytime soon, but understanding how much ice will melt in the next century is an important and pressing question, how are scientists trying to tackle ice using sophisticated numerical models? It interacts with the rest of the climate system.
The problem is that the specimens are not very good at reproducing recent observations, and are limited by our poor knowledge of the snowy terrain and the extensive terrain of the Fjords, which flow on and into the ice.
One way around this problem is to observe how ice has responded to climate change in the past and compare it to future models for similar temperature changes. This is exactly what my colleagues and I did in a new study published in the journal Now Nature Communications.
To reconstruct how the size of these glaciers changed between 1880 and 2012, we examined three large glaciers in Greenland and used historical aerial photographs along with measurements made directly by scientists over the years.
The approach is established not only in science but also in all aspects of life based on the idea that it can help predict the future.
But like other “classes” in history, the climate and the earth system in the future will not be a carbon copy of the past. However, if we find out how sensitive ice is to changes in temperature over the past century, it will provide useful guidance on how it will respond in the next century.
We found that three large glaciers caused a sea level rise of 8.1 mm, which represents about 15% of the glacier’s total contribution.
At the time of our study, sea level had risen by about 20 cm worldwide, about the height of manual A5, about the width of a finger, thanks in full to the melting of the ice of those three Greenlandic glaciers.
It usually melts
So what does it tell us about the future behavior of ice? In 2013, a modeling studio Foge Nick and colleagues saw the same “big three” glaciers (Jakobshawn Ispray to the west of the island and Hellheim and Kangarluzwak to the east) and predicted how they would respond to future weather conditions.
These scenes are called the most intense. RCP8.5 It assumes that economic growth will continue unabated into the 21st century, with warmer temperatures of around 3.7 degrees Celsius (pre-industrial or 1850 – 4.8 degrees Celsius).
This scenario is sometimes referred to as Business as Usual (PAU), and there is an active discussion on the reliability of RCP8.5 among climate researchers. However, according to a recent study by a group of American scientists, it is worth noting that this may be the most favorable situation. At least until 2050.
Since something is called polar multiplication, Arctic warming twice the global average, climate models indicate warming of about 8.3 ° C in Greenland, under the most extreme conditions, RCP8.5.
Despite this dramatic and terrifying rise in temperature, the “Big Three” predict a 9 to 15 mm sea level rise by 2100, slightly more than we received from the 1.5C warming of the 20th century. How can it be?
Our conclusion is that the models are also wrong. More recent and sophisticated available They are used to estimate how the whole iceberg will respond in the next decade. Climate change.
These models appear to have a relatively weak correlation between climate change and ice melt. Our results suggest it is very strong.
Predictions based on these models are therefore likely to predict how much ice will be affected. Other sources support this conclusion.
What does all this mean? If we continue on the dreaded RCP8.5 path of rising greenhouse gas emissions, Greenland’s ice sheet will begin melting at a rate we haven’t seen in at least 130,000 years, with sea levels and negative effects Millions of people Inhabitants of the coastal areas.
Jonathan Bomber, Professor of Physics and Geography, University of Bristol.
This article was republished Conversation under the Creative Commons license. Read the original article.
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