New Delhi: A new model using simulations to study the melting of Greenland Ice Sheet has determined two critical tipping points, in terms of carbon emissions, beyond each of which irreversible melting is expected to occur, according to a new study. Releasing 1000 gigatonnes of carbon would cause the southern portion of the ice to melt, scientists said in the study.
They further said that releasing 2500 gigatonnes of carbon meant a permanent loss of nearly the entire ice sheet.
Having emitted about 500 gigatonnes of carbon, we’re about halfway to the first tipping point, they said in the study published in the journal Geophysical Research Letters.
The Greenland Ice Sheet covers 1.7 million square kilometers in the Arctic. If it melts entirely, global sea level would rise about 7 metres, but scientists are not sure how quickly the ice sheet could melt.
The first tipping point is not far from today’s climate conditions, so we’re in danger of crossing it, said Dennis Honing, lead researcher and a climate scientist at the Potsdam Institute for Climate Impact Research, Germany. Once we start sliding, we will fall off this cliff and cannot climb back up, said Dennis Honing.
The Greenland Ice Sheet is known to already melt at a rate of 255 gigatonnes of ice each year, much of which happens in the southern part of the ice sheet.
The scientists said it is hard to predict how the ice sheet will respond to different climate and carbon emissions scenarios, owing to the complexity in factors such as air and water temperature, ocean currents, precipitation and others, all of which determine the rate and location of ice melting.
Previous research has identified global warming between 1 and 3 degrees Celsius to be the threshold beyond which the Greenland Ice Sheet will melt irreversibly.
To comprehensively model the ice sheet’s response to climate over time, Honing’s study used a complex model of the whole Earth system, which included key climate feedback processes, coupled with ice sheet behaviour model.
Using simulations, the team determined equilibrium states, where ice loss would equal ice gain. This was followed by running 20,000-year-long simulations with carbon emissions ranging from 0 to 4000 gigatonnes of carbon.
It is from here that the scientists derived the two aforementioned tipping points.
As the ice sheet melts, its surface will be at lower elevations, exposing it to warmer air temperatures, which accelerate melting, making it drop and warm further.
For this feedback loop to become effective, the scientists said that global air temperatures would have to remain elevated for at least hundreds of years.
However, once the threshold is crossed, they said, even pre-industrial levels of atmospheric carbon dioxide would not be enough to allow the ice sheet to regrow substantially.
We cannot continue carbon emissions at the same rate for much longer without risking crossing the tipping points, Dennis Honing said. Most of the ice sheet melting won’t occur in the next decade, but it won’t be too long before we will not be able to work against it anymore, Dennis Honing said.
(This story has not been edited by NDTV staff and is published from a syndicated feed.)
NDTV – Dettol have been working towards a clean and healthy India since 2014 via the Banega Swachh India initiative, which is helmed by Campaign Ambassador Amitabh Bachchan. The campaign aims to highlight the inter-dependency of humans and the environment, and of humans on one another with the focus on One Health, One Planet, One Future – Leaving No One Behind. It stresses on the need to take care of, and consider, everyone’s health in India – especially vulnerable communities – the LGBTQ population, indigenous people, India’s different tribes, ethnic and linguistic minorities, people with disabilities, migrants, geographically remote populations, gender and sexual minorities. In wake of the current COVID-19 pandemic, the need for WASH (Water, Sanitation and Hygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign will continue to raise awareness on the same along with focussing on the importance of nutrition and healthcare for women and children, fight malnutrition, mental wellbeing, self care, science and health, adolescent health & gender awareness. Along with the health of people, the campaign has realised the need to also take care of the health of the eco-system. Our environment is fragile due to human activity, which is not only over-exploiting available resources, but also generating immense pollution as a result of using and extracting those resources. The imbalance has also led to immense biodiversity loss that has caused one of the biggest threats to human survival – climate change. It has now been described as a “code red for humanity.” The campaign will continue to cover issues like air pollution, waste management, plastic ban, manual scavenging and sanitation workers and menstrual hygiene. Banega Swasth India will also be taking forward the dream of Swasth Bharat, the campaign feels that only a Swachh or clean India where toilets are used and open defecation free (ODF) status achieved as part of the Swachh Bharat Abhiyan launched by Prime Minister Narendra Modi in 2014, can eradicate diseases like diahorrea and the country can become a Swasth or healthy India.