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| Mon, 25th May 2020 12:07:00 |
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Climate change in deep oceans could be seven times faster by middle of century, report says |
Rates of climate change in the world's ocean depths could be seven times higher than current levels by the second half of this century even if emissions of greenhouse gases were cut dramatically, according to new research.
Different global heating at different depths could have major impacts on ocean wildlife, causing disconnects as species that rely on each other for survival are forced to move.
In the new research, scientists looked at a measure called climate velocity – the speed at which species would need to move to stay within their preferred temperature range as different ocean layers warm.
The study, published in the journal Nature Climate Change, found different parts of the ocean would change at different rates as the extra heat from increasing levels of greenhouse gases moved through the vast ocean depths.
By the second half of the century, the study found "a rapid acceleration of climate change exposure throughout the water column".
The study used climate models to first estimate the current rates of climate velocity at different ocean depths, and then future rates under three scenarios – one where emissions started to fall from now; another where they began to fall by the middle of this century; and a third where emissions continued to rise up to 2100.
Prof Jorge García Molinos, a climate ecologist at Hokkaido University and a co-author of the study, said: "Our results suggest that deep sea biodiversity is likely to be at greater risk because they are adapted to much more stable thermal environments."
At present, the world's heating was already causing species to shift in all layers of the ocean from the surface to more than 4km down, but at different speeds.
But even under a highly optimistic scenario, where emissions fell sharply from now, the ocean's mesopelagic layer – from 200m to 1km down – climate velocity would change from about 6km per decade to 50km by the second half of the century. But over the same period, climate velocity would halve at the surface.
Even at depths of between 1,000 and 4,000 metres, climate velocity would triple current rates, even if emissions dropped sharply.
Prof Anthony Richardson, of the University of Queensland and the CSIRO and one of the study's 10 authors, told Guardian Australia: "What really concerns us is that as you move down through the ocean, climate velocity moves at different speeds."
This could create a disconnect for species that rely on organisms in different layers.
Read original full article
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