Planet crossed 1.5 degrees in 2024: A global climate wakeup call
At a time when Los Angeles wildfires are leaving a trail of mass destruction charring thousands of homes and forcing tens of thousands to evacuate, in what President Joe Biden called the most catastrophic fires in California’s history, the Copernicus Climate Change Service has confirmed 2024 as the hottest year on record, with global average temperatures reaching 1.6°C above pre-industrial levels. This marked the first time humanity surpassed the critical 1.5°C warming threshold for a full calendar year, a stark warning about the planet’s escalating climate crisis.
The year’s extraordinary heat extended a streak of record-breaking temperatures that began in 2023. Over the two years, average global temperatures exceeded the 1.5°C benchmark, a limit set under the Paris Agreement to avoid the most catastrophic impacts of climate change. While not yet permanently breached, this temporary surpassing of the threshold is a dire indication of the rapid warming driven by human activity. Samantha Burgess, Copernicus’ climate deputy director, said data “should alarm us all”, while Britain’s Energy Security Minister Ed Miliband described the worsening climate crisis as a betrayal of future generations if left unaddressed.
Each month from January to June 2024 set new records for the warmest corresponding month globally, with the period from July to December ranking as the second warmest, following 2023. The 13-month streak of record-breaking monthly global average temperatures ended in June. Notably, 22 July 2024 became the hottest day ever recorded. Dr Friederike Otto from Imperial College London said there is an urgent need to transition away from fossil fuels, halt deforestation, and bolster societal resilience.
Sea surface temperatures (SSTs) also reached record highs in 2024. The annual average SST for the extra-polar ocean was 20.87°C, surpassing the 1991-2020 average by 0.51°C. This streak of record SSTs extended from January to June, following a similar pattern from the latter half of 2023. Despite the end of the El Niño event that began in 2023, SSTs remained unusually high due to persistent warming conditions. The elevated SSTs, along with increased atmospheric moisture, contributed to a surge in extreme weather events, including major storms and tropical cyclones.
In South Asia, 2024’s unprecedented temperatures exacerbated the region’s vulnerabilities. Intensified heatwaves, floods, and agricultural disruptions became alarmingly common. Anjal Prakash of the Indian School of Business said, “These climatic changes disproportionately affect vulnerable communities, magnifying existing socio-economic disparities. Immediate, evidence-based action is essential to mitigate these effects, embracing sustainable practices and policies prioritizing climate resilience.”
India, in particular, experienced its hottest year on record, with extreme weather events causing thousands of deaths and significant crop damage. Akshay Deoras from the University of Reading likened humanity’s treatment of the planet to using a limitless credit card, cautioning, “We are on track to see new warming records getting broken unless we immediately cut down the emission of greenhouse gases.”
In 2024, the total atmospheric water vapour reached record levels, about 5% higher than the 1991-2020 average. This contributed to increased heat stress worldwide, with approximately 44% of the globe experiencing at least “strong heat stress” on July 10, a new record annual maximum. Sea ice extent also reached new lows.
Around Antarctica, eight months of 2023 saw record-low sea ice levels, and this pattern persisted through much of 2024. Antarctic sea ice extent ranked second lowest for June to October and hit record lows in November. In the Arctic, sea ice extent was near average until July but fell significantly below average in the latter months.
Greenhouse gas concentrations in 2024 continued to rise, reaching record annual levels. Carbon dioxide levels climbed to 422 parts per million (ppm), a 2.9 ppm increase from 2023, while methane levels reached 1897 parts per billion (ppb), rising by 3 ppb.
Despite the grim statistics, there are opportunities to address the crisis. The falling costs of renewable energy, such as solar and wind power, offer a viable pathway to transition away from fossil fuels. Governments are now positioned to build healthy economies by accelerating the shift to clean energy.
Carlo Buontempo, Director of C3S, stressed that humanity’s future remains within its control. The year’s unprecedented conditions, while alarming, also serve as a clarion call for decisive global action. As Florence Rabier, ECMWF’s Director-General, pointed out, the data provided by climate monitoring services like C3S is critical to supporting international climate adaptation efforts.
As 2025 unfolds, climate scientists caution against interpreting potential temperature fluctuations as a pause in climate change. Paulo Ceppi from Imperial College London noted that natural processes like El Niño could cause short-term dips, but these do not alter the clear upward trajectory of global temperatures. “The recent heat was exacerbated by a decrease in the amount of cloud and sea ice. This confirms climate model predictions of melting sea ice and shrinking cloud cover,” he explained.