Sea surface temperatures across the tropical Atlantic Ocean were higher in March 2010 than any other time in the past 160 years – the UK’s Hadley Center has data going back to 1850. When temperatures in this region are warmer than average, very active hurricane seasons usually occur. There are some complex interactions between Atlantic SSTs and other phenomena across the globe, most notably El Niño, so the relationship isn’t exact or direct. 2005 was the last year Atlantic SSTs north of the equator were also significantly warmer than usual.
How much above average were SSTs? 1.26°C above average during March. That might not sound like it’s too much warmer than usual until you realize the previous record, set back in 1969, was 1.06°C. This year’s record handily beat that value. For additional context, the temperatures observed in March are closer to what are normally observed around June. Finally, the record tied with June 2005 as the biggest positive departure from average in the dataset.
Read on for a more detailed explanation of why this has happened.