New Antarctic Ice Tipping Point Discovered as Study Says We’ve Underestimated Melting

New Antarctic Ice Tipping Point Discovered as Study Says We’ve Underestimated Melting

SUB :Environment

SEC: Climate Change

Context:

• New research by the British Antarctic Survey (BAS) has discovered a concerning way that large ice sheets can melt due to warm seawater infiltrating the underside of ground-based ice.
• This phenomenon could represent a new “climate tipping point,” where a small change in ocean temperature leads to significant increases in ice melting and ice flow towards the sea.

Mechanism of Melting:

• Warm seawater can travel long distances beneath ice sheets and infiltrate the space between the land and the ice, causing localized melting.
• This process lubricates the ice bed, influencing the rate at which ice slides towards the sea, potentially accelerating ice loss.

Implications:

• Melting in the grounding zones of ice sheets shows tipping point-like behaviour, with small temperature changes causing substantial increases in melting and ice flow.
• Previous research underestimated the sensitivity and potential instability of Antarctic ice compared to Arctic ice, but recent declines in Antarctic sea ice extent highlight its vulnerability.
• The researchers emphasize that current ice sheet models lack the ability to simulate melting beneath grounded ice, which is critical for accurate projections of sea level rise.

Recent Trends and Projections:

• Antarctic sea ice extent increased steadily from 1978 to 2015, while Arctic ice melted significantly.
• Since 2017, Antarctic Sea ice has declined, reaching record lows in 2022 and 2023.
• The new understanding of melting mechanisms suggests that projections of sea level rise due to Antarctic and Greenland ice sheet changes might be significant underestimates. Researchers are working to incorporate this new knowledge into ice sheet models.

Tipping points:

• Several studies in the past 15 years have identified different tipping points such as the disintegration of the Greenland ice sheet, a spontaneous reduction in Amazon forest cover, melting of glaciers, or softening of the permanently frozen grounds in the polar regions that have large amounts of carbon trapped in them.
• Over the years, researchers have identified at least 15 tipping points, each correlated with different levels of temperature rise.
• The latest study has identified nine global and seven regional tipping points and has re-assessed their dynamics and correlation with global warming.