A report from the World Meteorological Organization shows that the global mean temperature in 2023 was 1.45 degrees Celsius above pre-industrial levels. It has never been this high since measurements began.
“Never before have we been so close – even temporarily – to the lower 1.5 degree threshold of the Paris Agreement on climate change,” said Celeste Saulo, secretary general of the World Meteorological Organization (WMO). What particularly worries researchers, in addition to the unusually high deviation in the air temperature measured at a height of two meters, is the unprecedented warming of the oceans, the retreat of glaciers and the loss of Antarctic sea ice, says Saulo.
António Guterres became even clearer: “The sirens are sounding on all indicators,” said the UN Secretary General. “Some records are not just chart-toppers, but chart-busters. And the changes are accelerating.”
Records not only in terms of temperature
On an average day in 2023, around a third of the world’s oceans were in the grip of marine heat waves, with damaging effects on ecosystems and food chains. By the end of the year, heat waves had occurred in 90 percent of all marine areas.
The reference glaciers monitored worldwide suffered the greatest ice loss since measurements began in 1950 and the extent of sea ice around Antarctica was by far the lowest ever recorded. The area of maximum expansion in September, i.e. in the southern winter, was one million square kilometers smaller than the previous record, which is roughly equivalent to the area of Germany and France combined.
Sea levels also reached record highs, reflecting both the increasing heat content of the oceans and the continued melting of glaciers and ice sheets. The rate of increase has more than doubled over the past ten years (2014 to 2023) compared to the first ten years since satellite measurements began (1993 to 2002).
Greenhouse gases continued to rise
Observed concentrations of the three major greenhouse gases – carbon dioxide, methane and nitrous oxide – reached record levels in 2022 and continued to rise in 2023. The carbon dioxide concentration is now 50 percent higher than in pre-industrial times. Due to the long residence time of carbon dioxide, the temperature increase is likely to continue for many years.
More extreme Temperature rise
In 2023, the global mean temperature was 1.45 degrees Celsius above the average for the years between 1850 and 1900. This eclipses the previous records from 2016 (+1.29) and 2020 (+1.27). From June to December, every month broke the previous record. September was even 0.46 to 0.54 degrees Celsius warmer than the warmest September to date.
The increase is primarily due to rising greenhouse gas concentrations. From the middle of the year, El Niño began in the Pacific, a warm water event, as a result of which large amounts of heat were released from the ocean into the atmosphere.
World’s oceans unusually warm
But it wasn’t just in the Pacific that the temperature of the water near the surface was unusually high. The sea water was also very warm in the North Atlantic, the Gulf of Mexico and the Caribbean, the North Pacific and large areas of the Southern Ocean and widespread marine heat waves occurred.
Heat content in the oceans reached record levels in 2023. Warming rates have shown a particularly sharp increase in the past two decades. This trend is expected to continue and remain irreversible for centuries to millennia.
Also noteworthy are the extensive marine heat waves in the North Atlantic that began in spring, peaked in September and lasted until the end of the year. Severe marine heatwaves were observed in the Mediterranean for the twelfth year in a row.
In addition, the further absorption of carbon dioxide has increased the acidification of the world’s oceans.
Sea ice decline in Antarctica
From February to November, the extent of Antarctic sea ice was lower than ever since satellite measurements began in 1979. The greatest extent in September was around 1.5 million square kilometers below the average for the years 1991 to 2020. The extent was in the Arctic of sea ice is also below average.
The Swiss Alpine glaciers have lost around ten percent of their remaining volume in the past two years. In western North America, glacier mass loss was around nine percent in 2023, five times faster than between 2000 and 2019.
Extreme events worldwide
Extreme weather and climate events such as floods, tropical cyclones, extreme heat and droughts had significant socio-economic impacts on all inhabited continents in 2023.
In September, depression “Daniel” caused extreme heavy rain in the eastern Mediterranean and claimed numerous lives, especially in Libya. Cyclone Freddy was one of the longest-lasting tropical cyclones and struck Madagascar, Mozambique and Malawi.
Cyclone Mocha, one of the strongest tropical cyclones ever observed, raged in the Bay of Bengal and Hurricane Otis intensified to the highest Category 5 within just five hours before reaching the Mexican Pacific coast near Acapulco on October 24th. Such rapid strengthening of a tropical storm has never been observed.
Extreme heat waves occurred primarily in southern Europe and North Africa. A new heat record of 48.2 degrees was registered in Italy, and in Agadir in Morocco it was even 50.4 degrees Celsius.
In Canada, 14.9 million hectares of forest burned down, clouds of smoke darkened the sky all the way to the US east coast. A forest fire in Hawaii killed at least 100 people. There were also severe floods in the Horn of Africa, which left around 1.8 million people homeless. In contrast, long-lasting droughts continued in northwest Africa and on the Iberian Peninsula as well as in parts of central and southwest Asia.
Energy transition is underway
In 2023, the capacity of renewable energy worldwide will have increased by 50 percent compared to the previous year, to a total of 510 gigawatts. This is the largest increase in two decades. The goal, formulated at the World Climate Conference in Dubai in November 2023, aims for a global capacity of 11,000 gigawatts by 2030.
Climate-related financial flows almost doubled in 2021/22 compared to 2019/20, reaching $1.3 trillion worldwide. However, in order to meet the 1.5 degree target, annual financing would have to increase to nine trillion US dollars by 2030 and ten trillion US dollars annually by 2050.
But doing nothing is even more expensive: the costs of the climate crisis between 2025 and 2100 could be an estimated $1,266 trillion – but could possibly be dramatically higher.
Kathrin Hondl, ARD Geneva, tagesschau, March 19, 2024 2:05 p.m