Heatwaves, floods, wildfires, and droughts unleashed global mayhem in 2023, as the year broke multiple climate records, according to the World Meteorological Organization’s (WMO) State of the Global Climate Report released this week.

It was the hottest year in recorded history, with global average near-surface temperature of 1.45℃ above the pre-industrial baseline.

“Never have we been so close – albeit on a temporary basis at the moment – to the 1.5° C lower limit of the Paris Agreement on climate change,” said WMO Secretary-General Celeste Saulo at a press conference this week.

“Climate change is about much more than temperatures. What we witnessed in 2023, especially with the unprecedented ocean warmth, glacier retreat and Antarctic sea ice loss, is cause for particular concern,” she said.

‘Climate crisis is the defining challenge that humanity faces’

The WMO’s annual report offers a dire snapshot of the world’s climate, sounding a “red alert” for countries to double down on efforts to control global warming. 

For United Nations (UN) Secretary General António Guterres, the earth itself is issuing a “distress call” as 2023 saw record greenhouse gas levels, surface temperatures, ocean heat and acidification, sea level rise, and Antarctic sea ice cover and glacier retreat. 

“The impact of all this is stark, brutal and accelerating with deadly force,” said Guterres in a video message at the launch of the report.

The report confirms 2023 as the hottest year on record, noting that globally, every month from June to December broke records. 

September 2023 was particularly noteworthy, surpassing the previous global record for that month by a wide margin (0.46 to 0.54 °C).

The shift from La Nina to El Nino weather conditions have exacerbated the greenhouse gas effects on warming, and the report also warns of rapidly warming oceans. 

At any given point in 2023, close to a third of the oceans were experiencing a heatwave, by the end of the year, most of the global oceans had experienced heatwave conditions. The most affected was the North Atlantic, with marine temperatures exceeding 3°C above average. 

However, the southern ocean continues to store the largest amount of heat, accounting for around 32% of the global ocean heat content (OHC) content increase since 1958. The Atlantic Ocean accounts for approximately 31% of the global 0–2000 m OHC increase; the Pacific Ocean around 26%.

These intense marine heatwaves harm entire ecosystems and further stress coral reefs. The combination of warming oceans and increased atmospheric carbon dioxide concentrations have further acidified the global ocean. The WMO expects the warming to continue “irreversibly” on a dramatic scale of “hundreds to thousands of years.”

Ice sheets shrink, sea level rise doubles 

Heatwaves are not the only phenomenon threatening the planet’s ocean. Global mean sea level reached record highs this year, while the rate of rise in the past ten years has doubled from 2.13 mm/year between 1993 and 2002, to 4.77 mm/year. 

Several factors converge to create this alarming rise: warmer oceans, the switch from La Nina to El Nino, and melting glaciers. 

Both glacier and sea-ice melt accelerated this past year, with Antarctic sea-ice reaching “an absolute record low” not seen since 1979. 

The Greenland Ice Sheet and Antarctic Ice Sheet lost 372 gigatonnes of mass per year from 2016 to 2020, up from 105 gigatonnes/year in 1992-1996.

“Antarctic sea ice was one million square kilometres smaller than the previous record low for the time of year. That’s an area almost 25 times the size of Switzerland,” noted Guterres. 

Beyond the poles, glaciers in western Northern America and Europe suffered the largest loss of ice on record, particularly in the European Alps. The mountain range lost 10% of its remaining volume in just the past two years. 

The toll of extreme weather

Extreme weather including cyclones, rainfall-induced flooding, wildfires, and heatwaves continued to lead to severe socioeconomic impacts. 

Wildfires in Hawaii, Canada and Europe led to loss of life, the destruction of homes and large-scale air pollution. Flooding associated with extreme rainfall from Mediterranean Cyclone Daniel affected Greece, Bulgaria, Türkiye, and Libya. 

“There were particularly devastating consequences for vulnerable populations who suffer disproportionate impacts,” writes WMO Secretary-General Saulo in her forward to the report.

“Extreme climate conditions exacerbated humanitarian crises, with millions experiencing acute food insecurity and hundreds of thousands displaced from their homes.”

Food security, population displacement and impacts on vulnerable populations continue to be of mounting concern in 2023, with weather and climate hazards exacerbating the situation in many parts of the world.

The report calls attention to the fact that the number of people who are acutely food insecure worldwide has more than doubled, from 149 million people before the COVID-19 pandemic to 333 million people in 2023, citing World Food Programme (WFP) numbers.

Climate and extreme weather events are directly tied to the dire food insecurity situation in much of the world; in Southern Africa, for example, Cyclone Freddy submerged extensive agricultural areas and inflicted severe damage on crops in February 2023.

“Across the globe, millions of people, including internally displaced persons, refugees, and migrants, are on the move or have been forced to flee their homes and communities because of disasters exacerbated by climate stresses and shocks,” states the WMO.

The consequences of global inaction

“The scientific knowledge about climate change has existed for more than five decades, and yet we missed an entire generation of opportunity,” said Saulo said to media in Geneva. 

She urged the climate change response to be governed by the “welfare of future generations, but not the short-term economic interests.”

The cost of inaction is staggering, the report warns. In the next 75 years, it may reach 1.266 trillion, representing the difference in losses between a business-as-usual scenario and a 1.5° C pathway. Noting that this figure is likely a significant underestimate, the UN weather experts call for immediate climate action.  

The report emphasizes that adaptation finance continues to be “insufficient.” Though adaptation finance reached an all-time high of 63 billion in 2021 and 2022, the global adaptation financing gap is widening, falling well short of the estimated 212 billion per year needed up to 2030 in developing countries alone.

There is, however, reason for hope. Renewable energy generation and capacity surged this past year, driven by solar, wind, and hydropower. 

In 2023, renewable capacity additions increased by almost 50% from 2022, for a total of 510 gigawatts (GW) – the highest rate observed in the past two decades.

“The good news is that we can still keep our planet’s long-term temperature rise below that limit, and avoid the worst of climate chaos,” remarked Guterres. “We know how to do it.” 

“There’s still time to throw out a lifeline to people and planet. But leaders must step up and act – now.”

Image Credits: Melissa Bradley, World Meteorological Organization.