Global Courant 2023-05-19 14:28:44
A year in the next five years will almost certainly be the hottest on record and there is a two in three chance that a single year will exceed the crucial global warming threshold of 1.5℃, an alarming new report predicted by the World Meteorological Organization.
The report, known as the Global annual to ten-year climate updatewarns that if humanity fails to reduce greenhouse gas emissions to zero, worsening heat records will tumble after this decade.
So what determines the bleak outlook for the next five years? An expected El Niño, on top of the general global warming trend, is likely to push global temperatures to record levels.
Has the Paris Agreement already failed if the global average temperature exceeds 1.5℃ in one of the next five years? No, but it will be a strong warning of what lies ahead if we don’t reduce emissions to net zero soon.
Warming makes record heat inevitable
According to the World Meteorological Organization update, there is a 98% chance that at least one of the next five years will be the hottest on record. And there is a 66% chance of going above the 1.5℃ threshold for at least one year.
There is also a 32% chance that the average temperature will exceed the 1.5℃ threshold in the next five years. The probability of a transient exceedance of 1.5℃ has steadily increased since 2015, when it was close to zero. For the years between 2017 and 2021, it was a 10% chance.
Man-made greenhouse gas emissions have already increased average global temperatures by more than 1℃ since the late 1800s. The update notes that the average global temperature in 2022 was about 1.15℃ above the 1850-1900 average, despite the cooling influence of La Niña conditions. Temperatures are now rising about 0.2℃ per decade.
Global mean surface temperatures over 1850-1900 from large datasets. The temperature is rising by about 0.2°C per decade. UK Met Office
We now have over a century of global mean temperature data. That means it should get harder, not easier, to hit new records. Were it not for a trend, we would expect fewer records to emerge over time and the data we have collected better reflect the full range of natural climate variability.
Instead, because we are warming the world so quickly, more heat records are being set worldwide and at local level. Human influence on the climate is driving temperatures to unprecedented heights with alarming frequency.
The current record global average temperature dates from 2016. An important El Nino event early that year caused the global average temperature to rise.
El Niño events are associated with warmer-than-normal seas over much of the central and eastern Pacific. This helps warm the lower atmosphere and raise the Earth’s temperature by about 0.1℃. This may not sound like much, but with rapid background warming, it is often enough to break the previous record.
In the seven years since the current global temperature record, humanity has continued to amplify global warming. This makes a new record increasingly likely.
El Niño conditions are starting to form in the Pacific and it looks increasingly likely that they will catch on in June and July. This could be the first significant El Niño since 2016. An El Niño would greatly increase the chances of breaking that year’s record high global average temperature, especially in 2024.
Does this mean that the Paris Agreement has already failed?
Almost all countries around the world have signed it Paris Agreement. The aim is to limit global warming to well below 2℃ and preferably below 1.5℃ above pre-industrial levels.
The prediction that an individual year with more than 1.5℃ of global warming is more likely than not is alarming. But that does not mean that we have failed to meet the objectives of the Paris Agreement. The agreement aims to limit long-term global warming to a level that avoids major climate impacts, including loss of ecosystems. One or two years going above the 1.5℃ level is not a failure.
A year in the next five years will almost certainly be the hottest year on record, with more heat waves like this kid in Britain around the time the latest record was set. Photo: Andy Rain/EPA via The Conversation
However, the world is getting closer to the level of 1.5℃ global warming thanks to our persistently high greenhouse gas emissions. The forecast of a likely year exceeding that level should serve as a warning.
Yet another sign of humanity’s damage to the climate
In the past, we have done nothing to reduce emissions and tackle climate change warmed the world by more than 1.2℃. Global emissions continue to rise near record highsso we continue enhance the greenhouse effect and warm the planet.
If we want to limit global warming to well below 2℃, then we must ensure that future generations do not suffer from a much less hospitable planet.
We’ve understood the solution for decades. We must reduce emissions to net zero to stop global warming. Countries such as Australia, with high historical emissions, are leading the way in decarbonising electricity supplies and reducing coal, oil and gas production in line with United Nations objectives.
Not acting should not be considered an option. Otherwise we will have more record hot years ahead and much worse consequences of climate change for the coming decades and centuries.
Andrew Kingsenior lecturer in climate science, The University of Melbourne
This article has been republished from The conversation under a Creative Commons license. Read the original article.
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