As the assessment now known as the BAMS State of the Climate report pushes into its third decade, international participation is at an all-time high. From atmospheric chemists to tropical meteorologists, more than 420 authors from institutions in 57 countries contributed to this year’s report.

2013 continued a trend of water vapor in the surface atmosphere increasing over land and ocean relative to the 1970s, while the atmosphere over land becomes less saturated. 

While the Northern Hemisphere’s snow cover on land ranked as the 13th most extensive on record in 2013, snow cover extent at the end of the cold season has dropped by 19.9 percent per decade since 1979 relative to the 1981-2010 average.

Globally-averaged surface temperature for 2013 was 0.36 - 0.38° Fahrenheit above the 1981–2010 average, placing it among the top 10 warmest years since record-keeping began.