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World climate on the brink of large-scale change, says international study

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By NewsGram Staff Writer

The global climate is on the verge of broad-scale change that could last for a number of decades, shows a study by British scientists.

The change is linked to cooling of the Atlantic, and is likely to bring drier summers in Britain and Ireland.

The study, which appeared in the journal Nature, is based on observational evidence of the link between ocean circulation and the decadal variability of sea surface temperatures called the Atlantic Multi-decadal Oscillation (AMO).

“Sea-surface temperatures in the Atlantic vary between warm and cold over time-scales of many decades. These variations have been shown to influence temperature, rainfall, drought and even the frequency of hurricanes in many regions of the world,” said lead author Gerard McCarthy from the National Oceanography Centre (NOC).

These climatic phases are the result of the movement of heat northwards by a system of ocean currents. This movement of heat changes the temperature of the sea surface, which has a profound impact on climate on time-scales of 20-30 years.

The strength of ocean currents has been measured by a network of sensors, called the RAPID array, which have been collecting data on the flow rate of the Atlantic meridonal overturning circulation (AMOC) for a decade. The authors used 100 years of sea level data, maintained by the National Oceanography Centre’s permanent service for mean sea level.

“By reconstructing ocean circulation over the last 100 years from tide gauges that measure sea level at the coast, we have been able to show, for the first time, observational evidence of the link between ocean circulation and the AMO,” said co-author Ivan Haigh, lecturer in coastal oceanography at the University of Southampton.

 

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Ice Loss in Antarctica and Greenland Increasing at an Alarming Rate: Scientists

Greenland, Antarctica ice loss accelerating

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Ice loss
Earth's great ice sheets, Greenland and Antarctica, were now losing mass six times faster than they were in the 1990s due to warming conditions. Pixabay

Earth’s great ice sheets, Greenland and Antarctica, were now losing mass six times faster than they were in the 1990s due to warming conditions, the media reported on Thursday citing scientists as saying.

A comprehensive review of satellite data acquired at both poles was unequivocal in its assessment of accelerating trends, the BBC quoted the scientists as saying.

Between them, Greenland and Antarctica lost 6.4 trillion tonnes of ice in the period from 1992 to 2017.

Ice loss
The combined rate of ice loss for Greenland and Antarctica was running at about 81 billion tonnes per year in the 1990s. Pixabay

This was sufficient to push up global sea-levels up by 17.8 mm, the scientists added. “That’s not a good news story,” said Professor Andrew Shepherd from the University of Leeds.

“Today, the ice sheets contribute about a third of all sea-level rise, whereas in the 1990s, their contribution was actually pretty small at about 5 per cent. This has important implications for the future, for coastal flooding and erosion,” he told BBC News.

The researcher co-leads a project called the Ice Sheet Mass Balance Intercomparison Exercise, or Imbie, which is a team of experts who have reviewed polar measurements acquired by observational spacecraft over nearly three decades.

The Imbie team’s studies have revealed that ice losses from Antarctica and Greenland were actually heading to much more pessimistic outcomes, and will likely add another 17 cm to those end-of-century forecasts.

“If that holds true it would put 400 million people at risk of annual coastal flooding by 2100,” Professor Shepherd told the BBC.

Also Read- People of All Generation Can Feel Lonely for Different Reasons: Research

The combined rate of loss for Greenland and Antarctica was running at about 81 billion tonnes per year in the 1990s.

By the 2010s, it had climbed to 475 billion tonnes per year. (IANS)