The World Meteorological Organization (WMO) has warned that the physical signs and socio-economic impacts of climate change are accelerating, driven by increasing global temperatures arising from record greenhouse gas concentrations.
The WMO Statement on the State of the Global Climate 2018 highlights key climate change indicators such as record sea level rise, as well as four consecutive years of exceptionally high land and ocean temperatures.
Petteri Taalas, WMO secretary-general, said, “Since the statement was first published, climate science has achieved an unprecedented degree of robustness, providing authoritative evidence of global temperature increase and associated features such as accelerating sea level rise, shrinking sea ice, glacier retreat, and extreme events such as heat waves.”
According to the report, these key climate change indicators are becoming more pronounced and are expected to continue. Carbon dioxide levels, which were at 357 parts per million when the statement was first published in 1994, keep rising – reaching 405.5 parts per million in 2017. For 2018 and 2019, greenhouse gas concentrations are expected to increase further.
The WMO climate statement includes input from national meteorological and hydrological services, an extensive community of scientific experts, and United Nations agencies. It details climate-related risks and impacts on human health and welfare, migration and displacement, food security, the environment, and ocean and land-based ecosystems. It also catalogs extreme weather around the world.
“Extreme weather has continued in early 2019, most recently with Tropical Cyclone Idai, which caused devastating floods and tragic loss of life in Mozambique, Zimbabwe and Malawi. It may turn out to be one of the deadliest weather-related disasters to hit the southern hemisphere,” said Taalas.
“Idai made landfall over the city of Beira: a rapidly growing, low-lying city on a coastline vulnerable to storm surges and already facing the consequences of sea level rise. Idai’s victims personify why we need a global agenda on sustainable development, climate change adaptation and disaster risk reduction.”
The start of this year has also seen record warm daily winter temperatures in Europe, unusual cold in North America and searing heatwaves in Australia. Arctic and Antarctic ice extent is again well below average.
According to WMO’s latest Global Seasonal Climate Update (March to May), above-average sea surface temperatures – partly because of a weak strength El Niño in the Pacific – are expected to lead to above-normal land temperature, particularly in tropical latitudes.
Climate impacts (based on input from UN partner agencies)
Hazards: In 2018, most of the natural hazards which affected nearly 62 million people were associated with extreme weather and climate events. Floods continued to affect the largest number of people; more than 35 million, according to an analysis of 281 events recorded by the Centre for Research on the Epidemiology of Disasters (CRED) and the UN International Strategy for Disaster Risk Reduction.
Food security: Exposure of the agriculture sector to climate extremes is threatening to reverse gains made in ending malnutrition. New evidence shows a continuing rise in world hunger after a prolonged decline, according to data compiled by United Nations agencies including the Food and Agriculture Organization and World Food Programme. In 2017, the number of undernourished people was estimated to have increased to 821 million, partly due to severe droughts associated with the strong El Niño of 2015–2016.
Displacement: Out of the 17.7 million Internally Displaced Persons (IDPs) tracked by the International Organization for Migration, over 2 million people were displaced due to disasters linked to weather and climate events as of September 2018. Drought, floods and storms (including hurricanes and cyclones) were the events that led to the most disaster-induced displacement in 2018. In all cases, the displaced populations have protection needs and vulnerabilities.
Heat, air quality and health: There are many interconnections between climate and air quality which are being exacerbated by climate change. According to the World Health Organization, between 2000 and 2016 the number of people exposed to heatwaves was estimated to have increased by around 125 million persons, as the average length of individual heatwaves was 0.37 days longer than that recorded in the period between 1986 and 2008. These trends raise alarm bells for the public health community as extreme temperature events are expected to further increase in their intensity, frequency and duration. Environmental impacts include coral bleaching and reduced levels of oxygen in the oceans. Others include loss of ‘blue carbon’ associated with coastal ecosystems such as mangroves, seagrasses and salt marshes, and with ecosystems across a range of landscapes.
Ocean heat: 2018 saw new records for ocean heat content in the upper 700m (2,300ft) and upper 2000m (6,560ft), topping the previous record set in 2017. More than 90% of the energy trapped by greenhouse gases goes into the oceans and ocean heat content provides a direct measure of this energy accumulation in the upper layers of the ocean.
Sea level: Sea level continues to rise at an accelerated rate. Global Mean Sea Level (GMSL) for 2018 was around 3.7mm higher than in 2017 and is the highest on record. Over the period from January 1993 to December 2018, the average rate of rise is 3.15 ± 0.3mm yr-1 while the estimated acceleration is 0.1mm yr-2. Increasing ice mass loss from the ice sheets is the main cause of the GMSL acceleration as revealed by satellite altimetry, according to the World Climate Research Programme Global Sea Level Budget Group, 2018.
Ocean acidification: Over the past decade, the oceans have absorbed around 30% of anthropogenic CO2 emissions. Absorbed CO2 reacts with seawater and changes the pH of the ocean. This process, known as ocean acidification, can affect the ability of marine organisms such as mollusks and reef-building corals to build and maintain shells and skeletal material.
Sea ice: Arctic sea ice extent was well below average throughout 2018 and was at record-low levels for the first two months of the year. The annual maximum occurred in mid-March and was the third lowest March extent in the 1979–2018 satellite record. The September monthly sea ice extent was the sixth smallest September extent on record. The 12 smallest September extents have all occurred since 2007. At the end of 2018, the daily ice extent was near record-low levels.
The Antarctic sea ice extent reached its annual maximum in late September and early October. After the maximum extent in early spring, Antarctic sea ice declined at a rapid rate with the monthly extents ranking among the five smallest for each month through the end of 2018.
Glacier retreat: The World Glacier Monitoring Service monitors glacier mass balance using a set of global reference glaciers with more than 30 years of observations between 1950 and 2018. The organization covers 19 mountain regions. Preliminary results for 2018, based on a subset of glaciers, indicate that the hydrological year 2017/18 was the 31st consecutive year of negative mass balance.
To download a copy of the WMO Statement on the State of the Global Climate 2018, click here. - April 2019