New York (dpa) - Between mid-2015 and early 2016, tens of thousands of dead birds were washed up on the coasts of the US west coast and Alaska. Now researchers have found the reason for the mass extinction among the guillotine lumens: lack of food due to high sea temperatures.
From 2014 to 2016, there was a large accumulation of unusually warm sea water in the Pacific off the coast, which was nicknamed the "blob" (roughly: blob), the researchers report in the journal "PLOS ONE".
The team led by John Piatt from the Alaska Science Center of the US Geological Survey in Anchorage used numerous sources to determine the extent of the mass extinction in detail, as well as the reproductive rate in the breeding colonies of the black and white seabirds.
According to this, more than 60,000 dummies or dead guillotines were washed up on the coast during the mass extinction. In total, around a million of the birds in the region were probably killed. In Alaska, the number of carcasses found was up to 1000 times higher than usual. Never before had a higher number of colonies been recorded in which there were no offspring between 2015 and 2017.
The sea heat wave had reduced the quantity and quality of the plankton, as a result the number of live fish had decreased, which in turn had been prey to the guillotine sums, and the metabolism of fish in the warmer water had run faster - predator fish had more prey due to the higher energy consumption needed and thus further reduces the number of fish available for the seabirds.
Other creatures were also affected, said Kevin Trenberth of the National Center for Atmospheric Research in the United States, whose team has just published a study on global warming. Among other things, around 100 million cod had died and whales had also suffered from the "blob".
Ocean heat waves caused by global warming have already occurred in the Tasman Sea and in other regions. "These effects of climate change have important consequences," said Trenberth. The mass extinction observed off Alaska and the US west coast could be a foretaste of what threatens with the rising sea water temperatures in the course of climate change, the researchers around Piatt fear.
The scientists around Trenberth and Cheng Lijing from China's Academy of Sciences (CAS) had calculated that the world's oceans were warmer than ever since global data collection began last year. The warming of the oceans due to climate change is also accelerating, they warned in the specialist magazine “Advances in Atmospheric Sciences”. The past ten years have seen the highest temperatures in the sea since the 1950s, with the youngest five years being the warmest.
The ocean temperature to a depth of two kilometers last year was about 0.075 degrees above the average from 1981 to 2010, the article said. The enormous amount of energy in the form of heat that man has brought to the oceans via climate change in the past 25 years corresponds to 3.6 billion atomic bomb explosions of the same magnitude as in Hiroshima, Japan.