782. Global Temperatures in the Next 5 Years Likely to be 1.5°C Above Pre-industrial Level for One Year

On May 17, the World Meteorological Organization (WMO) announced that the average temperature is likely to exceed 1.5°C above pre-industrial levels in at least one year during the five-year period 2023-2027. 

The global average temperature in 2022 was 1.15°C above the 1850-1900 average. The 3-year La Niña will end in March 2023, and global temperatures are expected to rise amid forecasts of a looming El Niño. The average global temperature for each year between 2023-2027 is projected to be 1.1°C to 1.8°C higher than the 1850-1900 average. There is a 66% chance that temperatures will exceed 1.5°C above pre-industrial levels, and a 98% chance that the highest temperatures on record will exceed those of 2016. In particular, the Arctic Ocean is warming dramatically and is projected to warm three times faster than the global average.

While noting that the projections do not imply that the temperature will exceed 1.5°C permanently, the WMO expressed concern about the enormous impacts on human health, food security, water and the environment that would result from an increasing likelihood of exceeding 1.5°C, even temporarily.

The 1.5°C number was set by the Paris Agreement, but since 2015, when the likelihood of that number was close to zero, the likelihood of approaching that number has increased every year.

To review why 1.5°C warming from pre-industrial levels is a problem, there is an alarm from climate science that 1.5°C warming is inevitable and that further warming should be avoided at all costs. Many climate models show substantial differences in temperature, precipitation, and other climatic conditions in most regions of the Earth's surface and oceans between the 1.5°C and 2°C warming cases. Slowing the rate of sea-level rise will give people and ecosystems living on islands and in low-lying coastal and delta regions time to develop adaptation measures. Similarly, a warming of 1.5°C compared to 2°C will reduce the threat of biodiversity loss and extinction and the extent of ocean temperature rise and acidification. Climate-related risks to health, livelihoods, food security, water supply, human security and economic growth increase at 1.5°C, but even more so at 2°C. Adaptation to 1.5°C warming is cheaper than to 2°C.

Rapid and far-reaching systemic transitions in energy, land use, cities, infrastructure and industry will be required to ensure that 1.5°C, if ever exceeded, is not significantly exceeded in the future.

Contributor: IIYAMA Miyuki (Information Program)