2023 warmest year on record, 2014-23 warmest decade ever, confirms WMO

The decadal average of the global mean surface temperature between 2014 and 2023 was 1.2 degrees Celsius higher than the pre-industrial average, making it the warmest 10-year period on record.

The WMO report noted that the observed concentrations of three main greenhouse gases — carbon dioxide, methane and nitrous oxide — also touched new records in 2022, the last year for which consolidated global figures were available. Carbon dioxide concentrations in 2022 had reached 417.9 parts per million, 150 per cent of the levels seen in the pre-industrial times, while methane concentrations were 1,923 parts per billion, which was 264 per cent of pre-industrial levels. Nitrous oxide concentrations in 2022 were observed at 335.8 parts per billion, which was 124 per cent of pre-industrial level, the report said.

Much of this information had been released in November last year, using data till October, in a provisional report that WMO brings out to coincide with the annual climate change conference. The data till October was so strong that none of the trends were expected to change during the remaining two months of the year.

“Concentrations of greenhouse gases continued to rise (in 2022). Ocean heat content and sea level reached record observed highs and the rate of increase is accelerating. Antarctic sea ice extent hit record observed lows. Key glaciers suffered record losses. The climate crisis is the defining challenge that humanity faces,” said Celeste Saulo, Secretary-General, WMO, in a statement.

With 70 per cent of Earth’s area covered by water, the rising greenhouse gases generate excess energy, which remains accumulated in the form of heat and is absorbed by oceans. In addition to this heat, oceans absorb carbon dioxide, which together with warming of the sea waters result in ocean acidification, rising sea level and more.

The ocean heat content in 2023 exceeded the 2022 value, thus reaching a 65-year high record, the WMO said.

“Though the rate of warming is not the same everywhere, the upper 2,000 metres of the ocean continued to warm last year. The strongest warming was recorded along the Southern, North Atlantic and the South Atlantic Oceans in 2023,” the report said.

The Mediterranean Sea and Atlantic Ocean remained unusually warm, besides the Pacific Ocean warming owing to the El Nino conditions that commenced in June last year.

As like heatwave and coldwave on land, there are ocean-equivalent components in the oceans known as marine heat wave and marine cold wave. 2023 being an El Nino year — when there prevails higher than normal sea surface temperatures along the equatorial Pacific Ocean — marine heat wave persisted along the North Atlantic Ocean.

According to WMO, at least 32 per cent area of the total global oceans suffered from marine heatwave everyday last year (23 per cent area during the 2016 El Nino episode). On the contrary, just under 4 per cent oceanic area experienced marine cold wave, underlining the extent of ocean warming in 2023.

High temperatures combined with warm oceans led to an unprecedented rate of melting of ice sheets and glaciers last year, resulting in a significant rise in the sea levels during 2023. “The rapid rise in sea level is likely due to El Nino,” the WMO report categorically stated.

During April and June, when El Nino conditions were setting-in, the sea level along the tropical Pacific Ocean surged above the long-term mean values. During July-September, the rising trend spread to central and South America regions. El Nino coupled with the positive Indian Ocean Dipole, the WMO said, contributed to the higher-than-average sea level along the Western Indian Ocean region last year.

Both the Arctic and Antarctic witnessed dramatic rates of sea-ice extent reduction during 2023. Antarctic sea-ice extent remained at rock bottom between June and early November corresponded also by slow ice growth rate owing to the warming Southern Ocean. The lowest ever sea-ice extent (since 1979 satellite data) here, measuring 1.79 million square km, was during February.

El Nino influences rainfall and is known to suppress rainfall over the Amazon basin, central America, southwest Europe, major parts of Africa and central Asia, southeast Asia and northern Australia, which was realised last year.

However over India, though there was a delayed onset of the southwest monsoon, the season ended up with 94 per cent of the seasonal long period average besides higher than usual rainfall recorded over central India region.

El Nino also triggered high intensity heatwaves, strong cyclones and hurricanes, including Cyclone Mocha in May last year that barrelled into Bangladesh wreaking havoc and displacing over two lakh people. A deadly wildfire raged through Hawaii, destroying 2,200 structures in Lahaina.

Heatwaves, floods, droughts, wildfires and intense tropical cyclones wreaked havoc on every continent and caused huge socio-economic losses.

“There were particularly devastating consequences for vulnerable populations who suffer disproportionate impacts. Extreme climate conditions exacerbated humanitarian crises, with millions experiencing acute food insecurity and hundreds of thousands displaced from their homes,” Saulo added.