Understanding Climate

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.

In 2012—for the 23rd consecutive year—mountain glaciers worldwide lost more mass through melting than they gained through new snow accumulation. The retreat of the majority of mountain glaciers worldwide is one of the clearest signs that climate is warming over the long term.

Upper ocean heat content has increased significantly over the past two decades. An estimated 70 percent of the excess heat has accumulated in the top 2,000 feet of the ocean, and the rest has flowed into deeper ocean layers.

In 2013, global average sea level was 1.5 inches above the 1993-2010 average, which is the highest yearly average in the satellite record (1993-present). Overall, sea level continues to rise at a rate of one-eighth of an inch per year.

The globally averaged sea surface temperature in 2013 was among the 10 highest on record, with the North Pacific reaching an historic high temperature. ENSO-neutral conditions and a negative Pacific Decadal Oscillation pattern had the largest impacts on global sea surface temperature in 2013.

Observing temperature patterns in the lower stratosphere gives scientists clues about our planet's changing climate. Global average temperatures in the lower stratosphere for 2013 were slightly below the 1981–2010 average.

From the strongest typhoon ever observed to historically high atmospheric carbon dioxide levels, the State of the Climate in 2013 report provides a complete rundown on the state of Earth's climate and how it is changing.

From reindeer to regional temperature patterns, from sea ice age to Greenland surface melt, the Arctic Report Card is a yearly assessment of the Arctic's physical and biological systems and how they are changing. This collection of visual highlights from the 2013 report is a story of the Arctic in pictures.

Since the mid-1960s, the Arctic has warmed about 3.6°F (2.0°C)—more than double the amount of warming in lower latitudes. In 2012 (the last complete calendar year available at the time scientists began working on the 2013 Arctic Report Card), the annual average temperature was the sixth warmest on record.

To be consistent with NOAA's use of 30-year periods for the official "climate normals," the National Snow and Ice Data Center switched its baseline period for sea ice analyses from 1979-2000 to 1981-2010.  Compared to the new normal, the low ice conditions of the recent past will appear less abnormal than they used to.