The global climate 2011-2015

Description

This report analyses the global climate 2011-2015 – the hottest five-year period on record  - and the increasingly visible human footprint on extreme weather and climate events with dangerous and costly impacts. The record temperatures were accompanied by rising sea levels and declines in Arctic sea-ice extent, continental glaciers and northern hemisphere snow cover. All these climate change indicators confirmed the long-term warming trend caused by greenhouse gases. Carbon dioxide reached the significant milestone of 400 parts per million in the atmosphere for the first time in 2015, according to the WMO report which was submitted to U.N. climate change conference.

Highlights:

• The warmest year on record to date was 2015, during which temperatures were 0.76 °C (1.37 °F) above the 1961–1990 average, followed by 2014. The year 2015 was also the first year in which global temperatures were more than 1 °C above the pre-industrial era.
• A strong La Niña event (2011) and powerful El Niño (2015/2016) influenced the temperatures of individual years without changing the underlying warming trend.
• Arctic sea ice continued its decline. Averaged over 2011-2015, the mean Arctic sea-ice extent in September was 4.70 million km2, 28% below the 1981–2010 average. The minimum summer sea-ice extent of 3.39 million km2 in 2012 was the lowest on record.
• During the satellite record from 1993 to present, sea levels have risen approximately 3 mm per year, compared to the average 1900–2010 trend (based on tide gauges) of 1.7 mm per year.

• Many individual extreme weather and climate events recorded during 2011–2015 were made more likely as a result of human-induced (anthropogenic) climate change.  In the case of some extreme high temperatures, the probability increased by a factor of ten or more. Examples include the record high seasonal and annual temperatures in the United States in 2012 and in Australia in 2013, hot summers in eastern Asia and western Europe in 2013, heatwaves in spring and autumn 2014 in Australia, record annual warmth in Europe in 2014, and a heatwave in Argentina in December 2013.

Reference information