Summer 2015 set to be world's hottest ever as US temperatures again soar

US had its 12-hottest summer but seven of the warmer seasons were in last 15 years. With ocean temperatures rising, scientists warn: 'It's definitely not good'

New data showing that the US had its 12th-hottest summer on record may not, at first glance, appear particularly significant or alarming.

But in announcing the news, climate scientists have pointed out that, of the 11 American summers that were recorded as warmer than 2015's, seven have occurred in the last 15 years; the other four were all during the "Dustbowl" 1930s heatwaves that plagued the US during the Great Depression.