07-25-2024

Earth just experienced its hottest day ever recorded

Earth.com staff writer

According to the Copernicus Climate Change Service (C3S), our planet has just experienced its hottest day in recorded history.

On July 22, 2024, the daily global average temperature reached a new record high of 17.15°C. This exceeded the previous records of 17.09°C set just one day before on July 21, 2024, and 17.08°C set a year earlier on July 6, 2023.

Hottest day on record

Based on preliminary data released by C3S on July 24, 2024, Monday, July 22, marked the hottest day in the ERA5 dataset, which has records dating back to 1940.

While the temperature on July 21, 2024 (17.09ºC) was nearly indistinguishable from the previous record of 17.08ºC reached on July 6, 2023, the new record temperature of 17.15°C on July 22 represents a more significant deviation than typical day-to-day variations.

What stands out even more is the significant difference between the temperatures recorded since July 2023 and those of all previous years. The data can be explored in Climate Pulse, the C3S application that provides historical and near-real-time temperature data from the ERA5 reanalysis dataset.

Global temperature record

Before July 2023, the previous daily global average temperature record was 16.8°C, set on August 13, 2016. Since July 3, 2023, there have been 58 days that have exceeded that previous record, spread between July and August 2023, and during June and July so far in 2024.

“On July 21st, C3S recorded a new record for the daily global mean temperature. What is truly staggering is how large the difference is between the temperature of the last 13 months and the previous temperature records. We are now in truly uncharted territory and as the climate keeps warming, we are bound to see new records being broken in future months and years,” said C3S Director Carlo Buontempo, commenting on the record set on July 21, 2024.

“We now have a new record, and its value is sufficiently large to indicate with some confidence that this has exceeded the record set only last year. The event is still ongoing and it is possible the date of the peak may still change, but our data suggest we may see slightly lower temperatures in the next few days,” he added, following the new record on July 22, 2024

Signs of the times

Analysis of the years with the highest annual maximum daily global temperatures shows that both 2023 and 2024 have seen annual highs substantially above those recorded in previous years.

Another sign of the global warming trend is the fact that the ten years with the highest annual maximum daily average temperatures are the last ten years, from 2015 to 2024.

The difference between the lowest-ranked of those ten years (2015) and the previous record prior to 2023 (August 13, 2016) was 0.2°C. The jump from the 2016 record to 2023 is 0.28°C, and to the new 2024 record is 0.35°C, highlighting how substantial the warmth of 2023 and 2024 is.

Forces behind the hottest day

But what caused this new record global average temperature? The global average temperature tends to reach its annual peak between late June and early August, coinciding with the Northern Hemisphere summer. This is because the seasonal patterns of the Northern Hemisphere drive the overall global temperatures.

The large land masses of the Northern Hemisphere warm up faster than the oceans of the Southern Hemisphere can cool down during the Northern summer months.

The global average temperature was already at near-record levels in recent days, slightly below the levels of 2023, after being at record levels for the time of year for more than a year.

The analysis suggests that the sudden rise in daily global average temperature is related to much above-average temperatures over large parts of Antarctica. Such large anomalies are not unusual during the Antarctic winter months and also contributed to the record global temperatures in early July 2023.

What’s more, Antarctic sea ice extent is almost as low as it was at this time last year, leading to much above-average temperatures over parts of the Southern Ocean.

Record global temperatures

As the global average temperature was already at near-record levels during the first half of July, close to the temperatures seen at this time of year in 2023, and the global average temperature typically reaches its peak at this time of year, it is not completely unexpected that we are seeing global average temperatures of this magnitude.

We expect the daily global average temperature to peak around July 22 or 23, 2024, and then decrease, but with possible further fluctuations in the coming weeks.

As the annual maximum global average temperature typically occurs between late June and early August, these conclusions are preliminary as scientists follow the evolution of the climate in near-real time.

In 2023, there was a second peak in the daily global average temperature on August 4 (reaching 17.05°C) that came close to the record set on July 6, 2023.

Hottest year on record?

Whether 2024 will likely be the warmest year on record will largely depend on the development and intensity of the next phase of the El Niño Southern Oscillation (ENSO) (i.e., when and how strongly La Niña develops).

To date, 2024 has been sufficiently warm for it to be quite possible that the full year will be warmer than 2023, but the exceptional warmth of the last four months of 2023 makes it too early to predict with confidence which year will be the warmer.