Source: Science and Technology Daily
Science and Technology Daily Beijing, January 28 (Reporter Zhang Mengran) A zoological study published in the British magazine Nature on the 28th pointed out that some species in the ocean are facing a crisis of "population collapse" - since 1970, the number of marine plate gills (that is, well-known sharks, rays, rays, rays) in the world has decreased by 71%, and more than 3/4 of these marine species are in a state of imminent extinction; while another study published at the same time pointed out the "climate crisis" of the ocean. Global surface temperatures have been rising for the past 12,000 years.
The oceans face multiple pressures, with climate change, rising sea temperatures, pollution, overfishing and acidification affecting their health. Scientists currently believe that the risk of extinction of marine species should come mainly from overfishing, but the decline of individual species has always been difficult to measure, and although declines in marine and coastal gill populations in different parts of the world have been previously recorded, no global analysis has been conducted.
This time, the team at Simon Fraser University in Canada estimated the relative abundance of 18 marine plate gill species from 1970 to 2018, assessing the extinction risk of all 31 marine plate gill species. They found that from 1970 to 2018, global marine plate gill abundance declined by 71.1 percent. Of these 31 species, 24 are on the brink of extinction, and three shark species (marine whitetip shark, Luxe shark, grooveless hammerhead shark) have declined to a particularly high degree and are now classified as critically endangered – the most threatened level on the IUCN list.
The researchers blamed the decline in these species on fishing pressure, which increased 18 times during this period. The research team noted that immediate action should be taken to prevent "stock collapse" and specifically called on governments to impose fishing restrictions to help promote species recovery.
In a climate report published the same day in the journal Nature, the Rutgers University team in New Jersey pointed out the "climate crisis" of the oceans. Global average annual sea surface temperatures have been rising over the past 12,000 years, the report said.
The researchers reinterpreted two of the latest climate models and devised a method to assess the seasonal bias of individual records to calculate the average annual sea surface temperature. They found that the warming between 12,000 and 6,500 years ago was caused by the retreat of the ice sheet, while the recent warming was caused by increased greenhouse gas emissions, and the current temperature is the highest temperature in the past 12,000 years, similar to the temperature of the last interglacial period about 125,000 years ago.
In addition to proposing that emissions continue to rise in sea surface temperatures, the study fills a long-standing gap between climate models and data previously used to reconstruct historical climate change in the Holocene.