‘Humanity is in charge of its own destiny’

‘This grim report confirms what last year’s unprecedented storms, floods and wildfires made obvious: world leaders are failing to tackle the climate crisis and hold fossil fuel companies to account. While millions around the world – including here in the UK – faced displacement and devastation by extreme weather, the fossil fuel giants driving the crisis continued banking billions while derailing global climate talks and obstructing change.
 
‘As the world’s most powerful climate denier returns to the White House, others must take up the mantle of global climate leadership. The majority of Brits want our leaders to stand up to the oil bosses and force them to stop drilling and start paying for the damage they are causing to our planet and everyone living on it.’

PHILIP EVANS
Campaigner at Greenpeace UK

Around Antarctica, after reaching record-low values for the time of year during eight months of 2023, the sea ice extent reached record or near-record low values again during a large part of 2024.

From June to October, the monthly extent ranked second lowest, behind 2023, and lowest in November. At its annual minimum in February, the monthly extent ranked third lowest in the satellite record.

In the Arctic, the sea ice extent was relatively close to its 1991–2020 average until July but fell well below average in the following months. At its annual minimum in September, the monthly extent ranked fifth lowest in the satellite record.

How 2024 became hottest year

Monthly temperature patterns provide a crucial clue to understanding some of the factors leading to 2024 becoming the hottest year on record.

The first half of the year was particularly warm, with each month recording higher global temperatures than the same month in any previous year. This contributed to a 13-month streak of record-breaking monthly temperatures, which ended in June.

From July onwards, global temperature anomalies remained significantly above average. August 2024 was as warm as August 2023, and the other months from July to December ranked as the second warmest on record, behind 2023. Notably, 22 July marked the hottest day ever recorded, with the global temperature reaching 17.16°C, according to ERA5.

The persistence of exceptionally high monthly global average temperatures during the first half of 2024 made it likely from late summer that it would surpass 2023 as the hottest year on record.

Furthermore, 2024 became the first year to register an annual temperature anomaly exceeding the 1.5°C threshold above the pre-industrial level.

The two-year average for 2023-2024 also exceeds this threshold. While this does not mean we have breached the limit set by the Paris Agreement — this refers to temperature anomalies averaged over at least 20 years — it underscores that global temperatures are rising beyond what modern humans have ever experienced.

‘Each year in the last decade is one of the 10 warmest on record. We are now teetering on the edge of passing the 1.5ºC level defined in the Paris Agreement and the average of the last two years is already above this level. These high global temperatures, coupled with record global atmospheric water vapour levels in 2024, meant unprecedented heatwaves and heavy rainfall events, causing misery for millions of people.’

SAMANTHA BURGESS
Strategic lead for climate, ECMWF

El Niño ands sea temperatures

High sea surface temperatures (SSTs) have been one of the most significant drivers behind the prevalence of high global temperatures in 2023 and 2024.

One of the factors behind these high SSTs was the evolution of the El Niño Southern Oscillation (ENSO). This ENSO peaked in December 2023 and continued to influence global temperatures in the first half of 2024.

Even as the El Niño event ended and the transition towards more neutral conditions in the equatorial eastern Pacific took place, many regions continued to experience unusually high SSTs, resulting in the global SST remaining higher than average. In 2024, annual average SST across the extra-polar ocean were at a record high.

Climate and extreme weather

In 2024, extreme weather events were observed worldwide, ranging from severe storms and floods to heatwaves, droughts and wildfires.

The increasing frequency and intensity of such events pose a significant risk to the livelihoods of people across the globe.

The total amount of water vapour in the atmosphere reached a record high in 2024, at about 5% above the 1991–2020 average — significantly higher than in 2023.

This abundant supply of moisture amplified the potential for extreme rainfall events.

In addition, combined with high sea surface temperatures, it contributed to the development of major storms, including tropical cyclones.

High temperatures can lead to situations where the body is under stress from overheating. As well as temperature, other environmental factors such as humidity can also impact heat stress.

In 2024, much of the globe experienced more days than average with at least ‘strong heat stress’. Some regions also saw more days than average with ‘extreme heat stress’, at which level it is imperative to take action to avoid heat stroke.

Prolonged dry periods in several regions created conditions conducive to wildfires. Large-scale and persistent wildfires were recorded across the Americas.

In terms of wildfire carbon emissions, Bolivia and Venezuela recorded their highest levels on record, while Canada saw its second highest levels, based on data from the Copernicus Atmosphere Monitoring Service (CAMS).