Annual State of the Climate Report for 2014 published
July 2015 - During 2014, the majority of climate indicators continued to reflect a warming planet, with several setting new records.
'State of the Climate in 2014' is the 25th consecutive instalment to the annual State of the Climate reports produced by the American Meteorological Society. These comprehensive reports are lead by scientists from NOAA , along with 413 scientists from 58 countries. Met Office scientist Kate Willett leads the Global Climate chapter and several other Met Office scientists contribute. The report provides a detailed update on global and regional Essential Climate Variables (ECVs) using all available climate monitoring records, including several produced by the Met Office Hadley Centre's HadOBS data portal. Patterns, trends and changes are tracked across the global climate system. All reports are freely available online.
The year 2014 was by all accounts a very warm year. The warmth was against the backdrop of an El Niño-Southern Oscillation (ENSO) that although often approached El Niño thresholds, at the time was considered officially neutral. The year's final months were since revised to 'marginal' El Niño. Long-lived greenhouse gases continued to increase, primarily owing to rising carbon dioxide (CO2) concentrations, in addition to methane (CH4), nitrous oxide (N2O) and other minor trace gases.
Over land surfaces, record level warmth was observed in Europe along with 24 other countries. The frequency of warm extremes were above average for all regions apart from North America. Similar spatial patterns were observed in the troposphere. Over oceans, global sea surface temperatures and ocean heat content were also observed to be exceptionally warm and sea level exceptionally high, keeping pace with the trend over the past two decades of 3.2 ± 0.4 mm per year.
Snow and Ice
In the cryosphere, the regions of the world containing snow and ice, the effect of increased warming continued to be visible in the decline of glacier volume. With the addition of seven more reference glaciers compared to 2013, preliminary results for 2014 make it the 31st consecutive year of negative glacier mass balance. Northern Hemisphere snow cover was near average. Arctic sea ice was well below average but above the exceptional lows seen in 2007, 2011 and 2012.
Global precipitation over oceans was above average, contrasting with below-average precipitation over land. This was also reflected in hemispheric soil moisture: the Southern Hemisphere, which is mostly ocean, was wetter compared to 2013 while the Northern Hemisphere, which is mostly land, was drier. These large-scale averages mask strong opposing (dry verses wet) features, often within close proximity. Water availability also dominated the FAPAR (Fraction of Absorbed Photosynthetically Active Radiation) variability which is a measure of the amount of vegetation covering the land surface. Over central Europe, high seasonal precipitation in combination with above average temperature created very favourable growing conditions. Humidity at surface level was above average in terms of the amount of water vapour, consistent with the high surface and tropospheric temperatures. However, relative humidity, a measure of how saturated the air is, remained below average, continuing a trend from around 2000.
Atmospheric Chemical Composition
The atmospheric concentration of long-lived greenhouse gases (CO2, CH4 and N2O) continued to increase bringing total radiative forcing to 36% above 1990 values. Atmospheric CO2 concentrations reached 397.2 ppm for the global average. Stratospheric ozone is very variable year-to-year but there is now evidence of a significant increase in the upper stratosphere since 2000. Global mean anomalies in stratospheric water vapour were positive (wet) due to warmer-than-average tropical tropopause layer temperatures, in stark contrast to the strongly negative (dry) global anomalies in 2013. Positive anomalies of carbonaceous aerosols, CO, and to some extent tropospheric column ozone, were correlated with regions of seasonal biomass burning.
The comprehensiveness of this report permits an increased portrayal of the interconnectedness of many facets of the climate system. This year upper tropospheric wind and upper tropospheric humidity are included for the first time. The former helps highlight, for example, the influence of the quasi-biennial oscillation on stratospheric water vapour and the latter plays a key feedback role in climate. Also included are three sidebars discussing uncertainty in temperature rankings, drought indices, and the Copernicus Atmospheric Monitoring System (CAMS).