Global temperatures are at around 1.34°C-1.41°C above pre-industrial levels, although 2024 was likely to have breached 1.5°C, the World Meteorological Organisation (WMO) said today in its State of the Global Climate 2024 report.
The long-term 1.34°C-1.41°C range is the best estimate currently possible, but "given the uncertainty ranges, the possibility that we have already exceeded 1.5°C cannot be ruled out", the WMO said.
The Paris climate agreement seeks to limit the rise in global temperatures to "well below" 2°C above pre-industrial levels, and preferably to 1.5°C. But last year was the hottest on record, at 1.55°C above the pre-industrial average, with a margin of uncertainty of 0.13°C either above or below that figure, the WMO said in January. The organisation uses datasets from six weather and science agencies.
Individual years that exceed the 1.5°C level do not mean that the Paris agreement goals are out of reach, as the temperature limits sought by the accord work on a timeframe of at least 20 years. But "it is a wake-up call that we are increasing the risks to our lives, economies and to the planet", WMO secretary general Celeste Saulo said.
The record-high temperatures in 2023 and 2024 were owed to "the ongoing rise in greenhouse gas emissions" (GHGs) as well as "a shift from a cooling La Nina to warming El Nino event", the WMO found. Other contributing factors may include solar cycle changes, volcanic eruptions and a decline in cooling aerosols, it added.
The atmospheric concentration of CO2 in 2023 was higher "than at any time in at least 2 million years", the WMO found. Concentrations of other key GHGs methane and nitrous oxide in 2023 reached their highest in the last 800,000 years, while data show that levels of those GHGs continued to increase in 2024, it added.
The concentration of CO2 in 2023 was at 420 parts per million (ppm) — 2.3ppm more than in 2022 — and at 151pc of the pre-industrial concentration. CO2 levels correspond to 3.276 trillion t in the atmosphere, the WMO said. Concentrations of methane and nitrous oxide in 2023 stood at 265pc and 125pc of pre-industrial levels, respectively.
The majority of surplus heat goes into warming the ocean, which — along with ice loss on land — causes sea levels to rise. The "rate of sea level rise has doubled since satellite measurements began", from 2.1mm/yr between 1993 and 2002, to 4.7mm/yr between 2015-2024, the WMO said.
The organisation also flagged the number of extreme weather events in 2024, citing wildfires, hurricanes, floods, droughts and more, which led to the "highest number of new displacements recorded for the past 16 years, contributed to worsening food crises, and caused massive economic losses".
