First it was January, then May, and now September.
New data by the European Union’s Earth Observation Programme showed on Wednesday that last month was the world’s hottest September on record, with unusually high temperatures recorded off Siberia, in the Middle East and in parts of South America and Australia.
It means that this year has now seen three months of record warmth, while June and April were virtually tied for first, according to the programme’s Copernicus Climate Change Service (C3S).
Globally, September was 0.05 degrees Celsius warmer than the same month in 2019 and 0.08C warmer than in 2016, previously the warmest and second warmest Septembers on record, C3S said.
Over the final three months of 2020, climate events such as the La Nina phenomenon and projected low levels of autumn Arctic sea ice will influence whether the year as a whole will become the warmest on record.
“As we go into an even warmer world, certain extremes are likely to happen more often and be more intense,” Copernicus’s senior scientist Freja Vamborg told Reuters news agency, pointing to heat waves and periods of intense rain as examples of this.
Extending a long-term warming trend caused by emissions of heat-trapping gases, high temperatures this year have played a major role in disasters from fires in California and the Arctic to floods in Asia, scientists say.
Since the late 1970s, the global thermometer has crept up 0.2 degrees Celcius every decade, according to EU data.
Under the landmark Paris climate agreement signed in 2015, countries agreed to attempt to cap warming at 1.5 degrees Celsius (34.7 Fahrenheit), which scientists say would avoid the most catastrophic effects of climate change.
But even though large emitters, including China and EU nations, have pledged to slash their emissions in the coming decades, overall, current policies would see temperatures rise far beyond the 1.5 degree level.
“The Earth has warmed a lot, and it will carry on warming if greenhouse gas emissions continue at the rate they are at the moment,” Vamborg said.
Across California, five of the state’s six biggest wildfires in history were still burning at the end of September [Noah Berger/AP] Global warming
Arctic sea ice, meanwhile, shrank to its second lowest extent last month, slipping below four million square kilometres (1.5 million square miles) for only the second time since satellite records began in 1978, according to C3S.
The Arctic ice cap floats on ocean water around the North Pole, and thus does not contribute directly to sea level rise when it melts. But it does accelerate global warming.
Climate change has also disrupted regional weather patterns, resulting in more sunshine beating down on the Greenland ice sheet, which is melting – and shedding mass into the ocean – more quickly than at any time in the last 12,000 years, according to a study last week.
In 2019, the ice sheet – which holds enough frozen water to lift global oceans seven metres (23 feet) – shed more than half-a-trillion tonnes, roughly equivalent to three million tonnes of water every day, or six Olympic-size pools every second.