It is known that the water on Earth is rising due to global warming. But scientists now believe they have a more accurate picture of how high global sea levels are.
The Antarctic Ice Sheet and the Greenland Ice Sheet, the two largest sources of ice melt, contain about 99% of the fresh water on Earth.
In the worst case scenario, meltwater from the Antarctic Ice Sheet to the south and the Greenland Ice Sheet to the north will add another 4.6 feet (1.4 meters) to sea levels by 2150, according to a new study.
While this may be of concern, it does not take into account other sources of sea level rise, such as ice caps and floating ice platforms, which have also melted.
Researchers say global mean sea levels have risen by about 7.8 inches (20 centimeters) over the past century, a trend likely to accelerate with global warming.
The new study was led by Jun Young Park of Busan National University in South Korea and Fabian Schlosser of the University of Hawaii.
“Because most of the world’s population lives near coasts, it is important to provide accurate predictions of future global and regional sea level trends,” the researchers say in their paper published in Nature Communications.
Our results show that estimates of future sea level rise depend primarily on complex interactions between ice sheets, icebergs, the ocean and the atmosphere.
The new study focused on water coming from melting ice sheets — vast stretches of land covered in ice over 19,000 square miles (those below are called ice sheets). The ice sheets are very lumpy – the Antarctic layer is about 1.9 miles thick – but previous studies have shown that both are losing mass due to climate change as air and ocean waters warm.
While the melting of ice from the two ice sheets is not the only cause of sea level rise, they are thought to be the biggest sources.
Others include ice caps and floating ice platforms, as well as thermal expansion, Earth runoff, and more.
For the new study, experts ran climate simulations based on state-of-the-art socio-economic shared pathways (SSPs).
These simulation scenarios from the Intergovernmental Panel on Climate Change (IPCC) show different ways the world is changing and are often used by researchers.
The five scenarios range from SSP1-1.9, in which carbon dioxide emissions are “very low” and go to zero by around 2050, to the frightening worst-case scenario SSP5-8.5, in which greenhouse gas emissions triple by 2075.
The researchers found that if SSP5-8.5 occurs, the contribution of just two ice sheets to global sea level rise would be 4.6 feet (1.4 meters) by 2150.
In the other two SSP scenarios, sea level rise was less significant – 0.6 feet (0.2 meters) for SSP1 and 4.6 feet (1.4 meters) by 2150.
Unfortunately, researchers have found that limiting global warming to 3.6 degrees Fahrenheit (2 degrees Celsius) above pre-industrial levels — a key goal of the Paris Agreement — is not enough to slow the pace of global sea level rise.
Achieving this goal will not prevent the irreversible loss of large areas of the western Antarctic ice sheet, which is smaller in mass than its eastern counterpart.
Another group of experts have already warned that the melting of the West Antarctic ice sheet could lead to a 10-foot rise in global sea levels.
A new study warns that only by limiting the rise in global temperatures to below 3.2 degrees Fahrenheit (1.8 degrees Celsius) compared to pre-industrial levels by the end of this century can accelerated sea level rise be prevented.
The researchers say their study explains “the complex interactions between ice sheets, icebergs, oceans and the atmosphere” in ways that other studies haven’t done before and are therefore more subtle.
At present, the Antarctic ice sheet’s response to global warming provides the “greatest uncertainty” in estimating future sea levels, they say.
Finding more meltwater on Earth’s ice sheets will be key to understanding the risks associated with “catastrophic” climate events, says Dr. Robin Smith of the University of Reading’s National Center for Atmospheric Science. While more work is needed to reduce the uncertainty in such projections, this study clearly shows the importance of taking immediate action to reduce anthropogenic greenhouse gas emissions as quickly as possible to mitigate the risks associated with the loss of large ice sheets.
Source: Daily Mail
You must log in to post a comment.