Photo: Alexander Kesselaar - BY-NC-ND

State of the global climate

The World Metrological Organization (WMO) reports on a number of worrying climate-related records for 2017.

2013-2017 warmest five-year period

2017 is set to be in the top three hottest years, with record-breaking extreme weather. The World Meteorological Organization’s (WMO) provisional statement on the State of the Climate says the average global temperature from January to September 2017 was approximately 1.1°C above the pre-industrial era. As a result of a powerful El Niño event, 2016 is likely to remain the warmest year on record, with 2017 and 2015 being second and/or third. 2013–2017 is set to be the warmest five-year period on record.

GHG emission increase

The rate of increase in CO2 from 2015 to 2016 was the highest on record, 3.3 parts per million/year, reaching 403.3 parts per million. Global average figures for 2017 will not be available until late 2018. Real-time data from a number of specific locations indicate that levels of CO2, methane and nitrous oxide continued to increase in 2017.

Millions displaced

In 2016, 23.5 million people were displaced during weather-related disasters. Consistent with previous years, the majority of these internal displacements were associated with floods or storms and occurred in the Asia-Pacific region. In Somalia, more than 760,000 internal displacements have been reported, according to the UN High Commissioner for Refugees and the International Organization for Migration (IOM).

Arctic sea ice at record-low levels

The extent of Arctic sea ice was well below average throughout 2017 and was at record-low levels for the first four months of the year, according to the National Snow and Ice Data Center and the Copernicus Climate Change Service. The Arctic annual maximum extent in early March was among the five lowest in the 1979–2017satellite record, and according to NSIDC data was at a record low. The five lowest maximum extents have occurred since 2006. A strong and persistent low-pressure system over the central Arctic helped to inhibit ice loss during the summer months. The Arctic sea ice reached its minimum in mid-September  2017, with an area 25–31 per cent below the 1981–2010 average for that time of year, and was among the eight smallest minimum extents on record. The ten smallest minimum extents have all occurred since 2007. The Antarctic sea ice extent was also well below average. The annual minimum extent in early March was record low, and the annual maximum extent in mid-October was at or near record-low levels. Sea ice conditions in the Antarctic have been highly variable over the past several years, with the record-high sea ice extents occurring as recently as 2015. The Greenland ice sheet saw an increase of more than 40 billion tons of ice due to above-average snowfall and a short melt season. Despite the gain in overall ice mass this year, it is only a small departure from the declining trend, with the Greenland ice sheet having lost approximately 3,600 billion tons of ice mass since 2002.

Ocean heat highest

Global sea surface temperatures are on track to be among the three highest on record says WMO. Global ocean heat content in 2017 to date has been at or near record-high levels. Elevated tropical sea surface temperatures which contribute to coral bleaching were not as widespread as during the 2015–16 El Niño. But some significant coral bleaching did still occur, including Australia’s Great Barrier Reef. UNESCO reported in June that all but three of the 29 coral reefs with World Heritage listing had experienced temperatures consistent with bleaching at some point in the 2014–2017 period.

Heatwaves increasing

According to the World Health Organization (WHO), the global health impacts of heatwaves depend not only on the overall warming trend, but on how heatwaves are distributed across regions where people live. Recent research shows that the overall risk of heat-related illness or death has climbed steadily since 1980, with around 30 per cent of the world’s population now living in climatic conditions that deliver prolonged extreme heatwaves. Between 2000 and 2016, the number of vulnerable people exposed to heatwave events has increased by approximately 125 million.

Source: WMO, 6 November 2017


In this issue