Weather Bee | Will July warming fall below the 1.5°C level?
The expectation of the 1.5°C threshold not being breached in July is not wishful thinking. Some gradual cooling in global temperatures was expected this year.
June was the 12th consecutive month when global temperature was warmer by 1.5°C or more from the pre-industrial average in at least one dataset that tracks global average temperature.
This trend is significant because limiting long-term global warming to under 1.5°C is one of the important goals of the Paris Agreement. However, an HT analysis shows that July might offer relief on this front. At least this is what the data from the month so far shows.
To be sure, the global temperature reaching or breaching the 1.5°C threshold in the past 12 months does not mean that we failed in achieving the most important goal of the Paris Agreement. While the interpretation of the goal might vary, it is commonly understood that the goal is meant for a longer-term climate and not individual months and years.
However, the 12-month streak was worrying for a reason. At least three datasets tracking global temperatures had breached the 1.5°C threshold in the 12-month running average by February. The ERA5 dataset of Copernicus Climate Change Service (C3S), from where the 12-month streak was first reported, had breached the threshold in the 12-month average in January.
This trend continuing in individual months beyond January meant that the 12-month running average continued to cross the 1.5°C threshold. This is where July temperatures so far offer some relief. The average warming in the first 15 days of the month compared to the 1850-1900 baseline (often used as a pre-industrial average) is 1.38°C. No individual day in the first half of the month breached the 1.5°C threshold either, something that has not happened in the ERA5 dataset in any month after May 2023.
To be sure, it is quite possible that the next half of the month warms up so much that July 2024 becomes the thirteenth consecutive month with a 1.5°C breach in the ERA5 data. However, if that happens, it will be a break from the trend of the past four months, when warming relative to the pre-industrial baseline has decreased every month. Since the warming in June was 1.50°C, even a small fall from that level will mean that the threshold will not be breached in July.
The expectation of the 1.5°C threshold not being breached in July is not wishful thinking. Some gradual cooling in global temperatures was expected this year since the warming in the Nino 3.4 region of the Pacific Ocean — used to track El Nino and La Nina events — was decreasing every month after December. El Nino is a periodic warming of the equatorial Pacific Ocean, which has a warming effect on global temperatures. La Nina, a periodic cooling of the equatorial Pacific, has the opposite impact. Since May, the equatorial Pacific has been “neutral”: neither El Nino nor La Nina.
Clearly, it is a breach of the 1.5°C threshold that will be surprising in July and not a fall from that level. However, this relief should not be taken as a reflection of efforts towards halting global warming. Even if July ends with a warming of 1.38°C – the level seen in the first half of the month – the 12-month average of global warming after July will be 1.63°C, well above the level it should be.
Similarly, while a part of this warming can be attributed to cyclical factors, that we have crossed the 1.5°C threshold for the first time in the past year means that factors operating every few years are not the bigger reason here.
Therefore, a gradual cooling continuing in July will be good news for the month and the rest of the year, but no guarantee that the trend will continue in the following years.
Abhishek Jha, HT’s assistant editor-data, analyses one big weather trend in the context of the ongoing climate crisis every week, using weather data from ground and satellite observations spanning decades.
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