What’s happening? There is a 66% likelihood of the world seeing temperatures rise by over 1.5C above pre-industrial levels in at least one year between 2023 and 2027, according to a report from the World Meteorological Organization (WMO). Under the 2015 Paris Agreement, countries pledged to try to keep global temperatures below this threshold. Breaching this level could cause a series of potentially irreversible impacts, scientists have warned. Although any rise above 1.5C before 2027 should only be temporary, it would still indicate an acceleration of humanity’s impact on the climate, while also moving the planet into “unchartered territory,” the WMO said. (The Guardian)

Why does this matter? Exceeding the 1.5C threshold means that four specific climate tipping points will become “likely”, while a further six will be “possible”, according to a 2022 study published in Science. Such tipping points include the collapse of Greenland’s ice sheet, coral reef die-offs ice loss in the Barents Sea, abrupt permafrost thawing and the collapse of the Atlantic Ocean conveyor belt, which could result in more extreme heat and cold on both sides of the ocean.

Increasing probability – Scientists believe that the world has already warmed by 1.1C. The hottest global average surface temperature previously recorded was 1.28C above pre-industrial levels, which occurred in 2016. The likelihood of exceeding 1.5C has risen from “close to zero” in 2015, to approximately 48% in 2022, to the newly revised 66%.

The latest WMO report warns that, even if the initial 1.5C breach is temporary, such short-term breaches could occur with “increasing frequency”. Such an argument has also been put forward by Dr Oliver Geden, a core writer on the synthesis report published by the Intergovernmental Panel on Climate Change (IPCC) in March. Geden claimed that the IPCC analysis made it clear that it was now unlikely that global warming “always will stay below 1.5C”. Global efforts should focus on returning to the 1.5C threshold as soon as possible after overshooting the target, Geden argued.

Warming planet – The new WMO analysis also confirms that the planet is set to experience record-high temperatures over the next five years. The organisation said that the highs registered over the past year, including in Europe which saw its hottest-ever summer, could be just the beginning of a new period of heatwaves. Such heatwaves will be driven by both climate change and a developing El Niño weather system, which is set to replace the cooling impact of the La Niña that has been in place for the past three years.

El Niño – In May, the WMO warned that there was a 60% chance that El Niño would develop by the end of July and an 80% chance of it forming by the end of September. The WMO’s latest report suggests that the emergence of a new El Niño means there is now a 98% likelihood that at least one of the next five years will be the hottest ever recorded. Such high temperatures will have “far-reaching repercussions for health, food security, water management and the environment”, according to WMO Secretary General, Professor Petteri Taalas.

Global weather disruption – What’s more, the global effects of El Niño are not limited to warming. The Americas, northern US and Canada typically experience colder winters. The US Gulf Coast, Ecuador and Peru experience increased rainfall, leading to coastal flooding and erosion. Southern Europe gets wetter weather while northern Europe experiences dryer and colder winters. Australia, India, and Indonesia generally have less rainfall which leads to droughts and wildfires and sea levels can rise by up to 0.5m in Indonesia due to hotter trade winds and expanding warm water. Adapting to this weather phenomena will be increasingly difficult as climate change continues to intensify.