98% chance 2023-27 will be hottest 5-yr period ever, 1 of those warmest: UN
The United Nations (UN) warned on Wednesday (May 17) that it is 98% likely 2023-2027 will be the warmest five-year period ever recorded and one of those years will the hottest ever as greenhouse gases and El Nino together push up temperatures globally.
The years from 2015 to 2022 were the hottest eight ever recorded, with 2016 being the warmest. But temperatures are forecast to rise further as climate change intensifies. “There is a 98% likelihood that at least one of the next five years, and the five-year period as a whole, will be the warmest on record,” the World Meteorological Organization (WMO) said.
Temporary breach
At the 2015 Paris Agreement, countries agreed to restrict global warming to “well below” 2 degrees Celsius above the average levels measured between 1850 and 1900 — and 1.5 degrees Celsius if possible. The global mean temperature in 2022 was 1.15 degrees Celsius above the 1850-1900 average.
According to the WMO, there is a 66% chance that annual global surface temperatures will exceed 1.5 degrees Celsius above pre-industrial levels in at least one of the years between 2023 and 2027, with a range of 1.1 degrees to 1.8 degrees Celsius forecast for each of those five years.
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WMO Secretary-General Petteri Taalas has explained that this breach of the target is not likely to be permanent. “WMO is sounding the alarm that we will breach the 1.5 degrees Celsius level on a temporary basis with increasing frequency,” he added.
The El Nino factor
El Nino — the large-scale warming of surface temperatures in the central and eastern equatorial Pacific Ocean, a phenomenon that occurs every two to seven years — will worsen the situation in 2024. The chances of El Nino developing are 60% by end-July and 80% by end-September, the WMO said earlier this month. Typically, El Nino increases global temperatures in the year after it develops.
“A warming El Nino is expected to develop in the coming months, and it will combine with human-induced climate change to push global temperatures into uncharted territory. This will have far-reaching repercussions for health, food security, water management and the environment. We need to be prepared,” Taalas has said.
Incidentally, much of the past three years enjoyed the cooling influence of La Nina conditions — the opposite of El Nino. Yet, some of hottest years were recorded in that time, thanks to greenhouse gases such as carbon dioxide, methane, and nitrous oxide being at a record high and trapping the heat in the atmosphere.
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Rising global mean temperatures
Mean near-surface temperatures of both land and sea have increased globally since the 1960s. The chances of temperatures temporarily exceeding 1.5 degrees Celsius above the 1850-1990 average have increased steadily since 2015, a year when they were considered close to zero.
“Global mean temperatures are predicted to continue increasing, moving us away further and further away from the climate we are used to,” said Britain’s Met Office scientist Leon Hermanson who headed the report. There is a 32% chance that the entire five-year mean between 2023 and 2027 will exceed the 1.5C threshold, said the Met Office.
According to the WMO, temperatures in 2023 are likely to exceed the 1991-2020 average in almost all regions except for Alaska, South Africa, South Asia, and parts of Australia. Parts of the South Pacific Ocean are likely to be cooler than average.
(With agency inputs)
