The World Meteorological Organisation has released its Statement on the State of the Global Climate for 2019, warning that 2019 was 1.1 °C warmer than the pre-industrial era and climate change is already 'very visible', and that more ambitious efforts are needed to keep the warming below 2 °C by the end of the century.
In his introduction, the United Nations Secretary-General, Antonio Guterres called on governments, civil society and business to heed the facts set out in the Statement and take urgent action to halt the worst effects of climate change.
“We are currently way off track to meeting either the 1.5 °C or 2 °C targets that the Paris Agreement calls for. We need to reduce greenhouse gas emissions by 45% from 2010 levels by 2030 and reach net zero emissions by 2050. And for that, we need political will and urgent action to set a different path.
“We need more ambition on mitigation, adaptation and finance in time for the climate conference (COP26) to be held in Glasgow in November. That is the only way to ensure a safer, more prosperous and sustainable future for all people on a healthy planet.”
The Statement was compiled by the WMO with input from national meteorological and hydrological services, leading international experts, scientific institutions and United Nations agencies. It documents impacts of weather and climate events on socio-economic development, human health, migration and displacement, food security and land and marine ecosystems.
Key messages of the Statement were:
The global mean temperature for 2019 was 1.1±0.1 °C above pre-industrial levels. The year 2019 is likely to have been the second warmest in instrumental records. The past five years are the five warmest on record, and the past decade, 2010–2019, is also the warmest on record. Since the 1980s, each successive decade has been warmer than any preceding one since 1850.
Global atmospheric mole fractions of greenhouse gases reached record levels in 2018 with carbon dioxide (CO2 ) at 407.8±0.1 parts per million (ppm), methane (CH4 ) at 1869±2 parts per billion (ppb) and nitrous oxide (N2 O) at 331.1±0.1 ppb. These values constitute, respectively, 147%, 259% and 123% of pre-industrial levels. Early indications show that the rise in all three – CO2, CH4 and N2 O – continued in 2019.
The year 2019 saw low sea-ice extent in both the Arctic and the Antarctic. The daily Arctic sea-ice extent minimum in September 2019 was the second lowest in the satellite record. In Antarctica, variability in recent years has been high with the long-term increase offset by a large drop in extent in late 2016. Extents have since remained low, and 2019 saw record-low extents in some months.
The ocean absorbs around 90% of the heat that is trapped in the Earth system by rising concentrations of greenhouse gases. Ocean heat content, which is a measure of this heat accumulation, reached recordhigh levels again in 2019
Over the decade 2009–2018, the ocean absorbed around 23% of the annual CO2 emissions, lessening the increase in atmospheric concentrations. However, CO2 absorbed in sea water decreases its pH, a process called ocean acidification. Observations from openocean sources over the last 20 to 30 years show a clear decrease in average pH at a rate of 0.017–0.027 pH units per decade since the late 1980s.
As the ocean warms it expands and sea levels rise. This rise is further increased by the melting of ice on land, which then flows into the sea. Sea level has increased throughout the altimeter record, but recently sea level has risen at a higher rate due partly to increased melting of ice sheets in Greenland and Antarctica. In 2019, the global mean sea level reached its highest value since the beginning of the high-precision altimetry record (January 1993).