U. S. researchers have analyzed field data from the Antarctic Peninsula and the adjacent Scotia Sea area and found that since the 1970s, local temperatures have risen by 5 to 6 degrees Celsius, and the increase in mammals from other seas has led to predator competition among Antarctic mammals. As a result, the density of krill, which is the main food source for mammals in the above areas, has decreased by 80%. At the same time, the number of Adelie penguins and hooded penguins living in the area, which are based on krill, has also decreased sharply. From this we can infer:. ['Rising temperatures have increased competition for predators in Antarctic marine mammals.', 'If the density of krill continues to decrease, both Adelie penguins and hooded penguins will become extinct.', 'Warming and increased competition for mammalian predators threaten hooded penguin production.', 'Temperature rise has greatly damaged the ecological environment in Antarctica.']