SNIPPETS

Gulf Stream, off Svalbard warming

In what may be an indication of global warming affecting the Arctic first, the Gulf Stream off Svalbard has been found the warmest in the last 2,000 years. In that period, temperatures in the Gulf Stream off Svalbard measured roughly 3.5 degrees Celsius.

In the past 30 years, however, a warming of roughly two degrees occurred – an unusually high increase seen from a perspective of two millennia. “This is troubling. These somewhat disquieting findings in Science are based on high-quality data,” said Morten Hald of the University of Tromso, Norway.

Published in Science, the analysis shows substantially higher temperature increase in the Arctic compared to marine temperatures worldwide. Scientists collected sediment core samples from undisturbed seabed mud in the Fram Strait to reconstruct marine temperatures of the past.

They also counted zooplankton microfossils in the cores to get an idea of the temperature shift. “The different species of foraminifer micro-fossils prefer different temperatures – so counting which type is most prevalent in a deposit tells us about the ocean temperature at the time they were alive,” he said.

“We know the same organisms exist today and the temperatures at which they thrive. So we we have a basis for comparison. We have formulas for converting species composition into ocean temperature,” Hald said, adding that the team spent years counting these organisms from over 300 samples. For 2,000 years, the proportion of zooplanktons that prefer warmer temperatures in Arctic waters was roughly 30 pc.

But in the last 100 years, this proportion has risen to nearly 70 pc – and the bulk of this increase has occurred in the past 30 years. Chemical composition of the fossils was also analysed to know about ocean temperature when the shells were formed.” The results corroborate each other.

A similar temperature increase occurred 9,000 years ago, most likely due to the fact that solar radiation at that time was 10 per cent greater than today. But in the absence of high radiation today, it was difficult to point to any obvious natural drivers to explain this increase entirely, he said.

KR

No space for industrial fisheries

These fisheries spread between 1950 and 2005. There was a nearly five-fold increase in the catch from 19 million tonnes in 1950 to 90 million tonnes in the late 1980s. It tripled in 1980-90s, but  dropped to 87 million tonnes in 2005.

Down To Earth Features

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