Nasa described ice shelves as the 'gatekeepers' for glaciers flowing from Antarctica towards the ocean.

Cape Town - The global average land and sea surface temperature for January to April was the hottest ever recorded for this three-month period.

And scientists say the 10 000-year-old Larsen glacier in the Antarctic is cracking up and may shatter and disappear by the end of the decade.

The National Oceanic and Atmospheric Administration (NOAA) in the US, which has recorded temperatures since 1880, said the record high for the months of January to April had surpassed the previous record of 1998.

This comes after world temperatures for December to February were the hottest ever recorded for those three months.

NOAA said this week the record temperature for January to April was 0.8ºC above the 20th-century average. The global average for this period over the world’s land surface was 1.48ºC hotter than the 20th-century average – surpassing the previous record of 2007 by 0.05ºC.

The global sea surface temperature for January to April was 0.55ºC above the 20th-century average, which tied with 2010 as the second highest sea surface temperature for January to April. The highest sea surface temperature for these months was in 1998.

The eastern part of Canada and north-eastern part of the US were the only places that recorded much colder than average temperatures so far in 2015. Parts of the north Atlantic Ocean, eastern Atlantic Ocean and north-west Pacific Ocean were a bit cooler than average in the year’s first four months.

Findings of a new Nasa study have warned that the Larsen B ice shelf in the Antarctic, which partially collapsed in 2002, is weakening fast. Nasa scientist Ala Khazendar said on the agency’s website that the ice shelf was flowing faster, becoming increasingly fragmented and developing large cracks.

“This ice shelf has existed for at least 10 000 years, and soon it will be gone,” Khazendar said.

Nasa described ice shelves as the “gatekeepers” for glaciers flowing from Antarctica towards the ocean. When the ice shelves around Antarctica disappear, the glaciers from continental Antarctica are not held back and move into the ocean faster. This in turn leads to sea level rises.

Khazendar said his estimates of the Larsen glaciers’ remaining lifespan was based on the likely scenario that a huge, widening rift that had formed would eventually crack all the way across. The free-floating part of the glacier would then shatter in hundreds of icebergs and drift away on the ocean currents.

“It’s bad news for our planet. This ice shelf has existed for at least 10 000 years, and soon it will be gone,” he said on Nasa’s website.

 

The Larsen B ice shelf covers about 1 600km² and is about 500m thick.

Cape Times