Ocean heatwaves have become far more frequent

Additional annual heatwave days

in 1987-2016 compared with 1925-1954

6

12

18

24

30

Additional annual heatwave days in 1987-2016 compared with 1925-1954

6

12

18

24

30

Source: Smale et al, Nature Climate Change, 2019. Note: Map divided into one-degree squares of ocean