The signs and impacts of global warming are speeding up, the latest report on climate change published ahead of key UN talks in New York said, warning that the 2015-2019 period is set to be the warmest five years on record.
The United in Science report compiles the latest information about climate change from leading science experts in cooperation with the World Meteorological Organization.
It found that accelerating climate impacts were to blame for the five-year temperature record, as the global average temperature increased by 1.1°C above pre-industrial (1850-1900) times and 0.2°C warmer than 2011-2015.
“For the four year period, average temperatures were the highest on record for large areas of the United States, eastern parts of South American, most of Europe and the Middle East, northern Eurasia, Australia, and areas of Africa south of the Sahara,” said the report, adding that July 2019 was the hottest month on record globally.
Main consequences
The report said that the main consequences of the temperature increase have been a rise in sea levels, the shrinking of polar ice and glaciers, rising acidity of ocean water, extreme weather events, and wildfires.
Between May 2014 and 2019, sea-level rose at a rate of 5 mm per year, compared to 4 mm/year in the 2007-2016 period and 3.2 mm/year since 1993. One of the key factors was the rapidity of melting ice sheets and glaciers in the last couple of years as well as the rapid rate of ocean warming.
Arctic summer sea-ice extent — the area of sea with a specified amount of ice — has declined at a rate of approximately 12% per decade during 1979-2018. The four lowest values for winter sea-ice extent occurred between 2015 and 2019.
Overall, the amount of ice lost annually from the Antarctic ice sheet increased at least six-fold between 1979 and 2017. Glacier mass loss for 2015-2019 is the highest for any five-year period on record.
The report also said 90% of extreme weather events such as storms, floodings, and heatwaves are related to weather. In the studied five-year period, heatwaves were the deadliest extreme weather event that affected all continents and resulted in various new temperature records.
Wildfires are also influenced by climate change, the report showed, and they lead to major releases of carbon dioxide to the atmosphere. During the summer of 2019, unprecedented wildfires ravaged the Arctic region. Fifty megatons of carbon dioxide were emitted into the atmosphere in June as a result, which was more than was released by Arctic fires in the same month from 2010 to 2019 put together.