COP29: Climate emergency - 2024 sets a new heat record

The World Meteorological Organization (WMO) has announced that 2024 is on the path to becoming the warmest year ever recorded, following an unprecedented series of months marked by exceptionally high global mean temperatures.

Key highlights

• From January to September 2024, the global average temperature was 1.54°C (with an uncertainty margin of ±0.13°C) above pre-industrial levels.

• Long-term warming remains under 1.5°C.

• The last decade, spanning 2015 to 2024, is confirmed as the warmest on record, with rising ocean heat and accelerating ice loss.

• Antarctic sea ice reached its second-lowest extent, and glacier loss is worsening.

• Extreme weather and climate events have led to severe economic and human consequences.

The global mean surface air temperature for January through September 2024 was recorded as 1.54°C higher than the pre-industrial average, spurred by the effects of an ongoing El Niño event. This figure is supported by an analysis that draws upon six international datasets utilised by the WMO.

UN Secretary-General António Guterres emphasised, “Climate catastrophe is hammering health, widening inequalities, harming sustainable development, and rocking the foundations of peace. The vulnerable are hardest hit.”

This report was released on the first day of the UN Climate Change Conference (COP29) in Baku, Azerbaijan, drawing attention to the significant challenges threatening the Paris Agreement targets. WMO Secretary-General Celeste Saulo stressed, “As monthly and annual warming temporarily surpass 1.5°C, it is important to emphasise that this does NOT mean that we have failed to meet [the] Paris Agreement goal to keep the long-term global average surface temperature increase to well below 2°C.”

Saulo highlighted the new normality brought by extreme weather events: “The record-breaking rainfall and flooding, rapidly intensifying tropical cyclones, deadly heat, relentless drought, and raging wildfires that we have seen in different parts of the world this year are unfortunately our new reality and a foretaste of our future... We urgently need to reduce greenhouse gas emissions and strengthen our monitoring and understanding of our changing climate. We need to step up support for climate change adaptation through climate information services and early warnings for all.”

Annual temperature overview: Projections indicate that the global mean temperature in 2024 is likely to surpass that of 2023, the current warmest year on record. This would mark 16 consecutive months, from June 2023 to September 2024, where global mean temperatures have reached unprecedented levels. According to the WMO’s integrated analysis, many of these months exceeded previous records by a substantial margin.

It is critical to understand that an individual year with temperatures exceeding the 1.5°C threshold does not imply that the goal of “pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels,” as outlined in the Paris Agreement, is no longer achievable. Instead, surpassing this threshold should be seen in the context of long-term warming, usually measured over extended periods like decades. Current estimations from experts assembled by the WMO suggest long-term global warming is about 1.3°C above the 1850-1900 baseline.

Ocean heat content: The ocean, which absorbs over 90% of the energy accumulated by the Earth’s system, recorded its highest heat content in 2023. Preliminary data indicates that 2024 has maintained these record levels. The rate of ocean warming has seen a substantial increase in the last two decades. From 2005 to 2023, the ocean absorbed an estimated 3.1 million terawatt-hours (TWh) of heat annually, which surpasses global energy consumption in 2023 by more than 18 times. Given the vast heat storage in the oceans, the warming trend is expected to persist over centuries to millennia.

Sea level rise: The acceleration in sea level rise is a direct consequence of thermal expansion from warming waters and melting ice sheets. Between 2014 and 2023, the global mean sea level rose at an average annual rate of 4.77 mm, more than double the rate observed from 1993 to 2002. The presence of El Niño in 2023 exacerbated this trend, but preliminary 2024 data suggests a return to the pre-existing upward trajectory consistent with levels observed from 2014 to 2022.

Glacier loss: 2023 marked a record year for glacier loss, with glaciers losing an average of 1.2 meters water equivalent of ice—around five times the volume of the Dead Sea. This was the most substantial annual loss since measurements began in 1953, spurred by significant melting in regions like North America and Europe. Notably, Swiss glaciers experienced around 10% volume loss over 2021/2022 and 2022/2023.

Impact of weather and climate extremes: Extreme weather events in 2024 undermined sustainable development, aggravating food insecurity and contributing to displacement and migration. Record-breaking heat waves affected millions, while intense rainfall, tropical cyclones, and widespread flooding led to considerable loss of life and damage. Persistent drought conditions, worsened by El Niño, were also significant.

The final State of the Global Climate 2024 report, scheduled for release in March 2025, will include more comprehensive details on these climate impacts, provided by UN partners.

Climate services and early warnings: Significant progress has been made over the past five years in climate services and early warnings. Initiatives like Early Warnings for All (EW4All) aim to ensure that by 2027, everyone will have access to life-saving early warning systems for hazardous weather, water, or climate events. Currently, 108 countries report having operational Multi-Hazard Early Warning Systems.

Understanding climate variability and change is essential for optimising renewable energy production, ensuring the resilience of energy systems, and analysing energy needs for heating and cooling.