Title Image Credit: Chris Yarzab/CC BY 2.0
You just experienced the World’s Hottest Day (So far)
On July 22, 2024, the world reached its highest global daily average temperature ever recorded, a stunning 17.16°C (62.87°F). In fact, the previous record of 17.08°C, set on July 6, 2023, was surpassed in 2024 by four days in succession, from July 21 through July 24.
To put this into perspective, it is likely that these were the hottest days in the last 120,000 years.
Before July 2023, the previous record was 16.8°C, set on August 13, 2016—a record that lasted for nearly seven years. As an indicator of how rapidly the climate is warming, from July 3, 2023 to July 23, 2024 there were 59 days that exceeded that earlier record.
At face value, these temperatures may seem too low to be “records,” but remember that the daily average encompasses hourly average temperatures, day and night, over the entire globe, including the oceans (70% of the earth’s surface), the Arctic and the ice-covered Antarctic.
Figure 1: Setting an all-time global daily temperature record. Likely the hottest day in over 1,000 years.
Analysis of the highest annual maximum daily global temperatures in preceding years (Fig. 2), shows that the last 10 years (2015 – 2024) recorded the highest annual maximum temperatures in the last 50 years. The difference in the annual maximum temperature from 2015 to 2024 is 0.56°C (1.01°F) — a remarkable change in just 10 years.
Figure 2: Annual maximum temperatures since 1974
On a monthly global basis, June 2024 was the thirteenth consecutive month to set a new monthly record, and the twelfth consecutive month at least 1.5°C warmer than the corresponding preindustrial monthly average. The period from July 2023 through June 2024 was the hottest 12 month period ever recorded for 138 countries. While a modest El Niño boosted temperatures in 2023 and early 2024, that uplift was on top of the steady increase of global warming. The transition to cooler La Niña conditions in the last half of 2024 will likely break the remarkable string of monthly temperature records. Nonetheless, the last thirteen months were remarkable. In the words of Carlo Buontempo, the Director of Europe’s Copernicus Climate Change Service: “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.”
While the 13-month chain of records may be at an end, Berkeley Earth reports that the 12-month moving average of global mean temperature is now 1.68°C (3.02F) above the preindustrial average (Fig. 3).
Figure 3. 12-month moving average global mean temperature. The trend in the data is shown in red.
Taking all this into account, it will come as no surprise that the scientists at Carbon Brief believe that there is a 95% chance that 2024 will be the warmest year on record. Given a likely cooling under the coming La Niña, their current best estimate for the 2024 average is 1.57°C (2.83°F) above the preindustrial average. Note that this will not indicate that we have crossed the Paris Agreement limit of 1.5°C, which refers to a 20-year average. However, we will reach that point soon enough — likely in the late 2020s or early 2030s.
Meanwhile, we are suffering the consequences of a warming planet, notably extreme heat waves.
Heat Waves
The same week that the global average daily temperature set a new record high, UN Secretary-General António Guterres issued a Call to Action on Extreme Heat. Warning that we are suffering from an “extreme heat epidemic,” Guterres called for action to limit the impacts of heat waves intensified by climate change.
Announcing the Call to Action, Gutteres said “But let’s face facts: extreme temperatures are no longer a one day, one week or one month phenomenon. If there is one thing that unites our divided world, it’s that we are all increasingly feeling the heat. Earth is becoming hotter and more dangerous for everyone, everywhere. Billions of people are facing an extreme heat epidemic—wilting under increasingly deadly heatwaves, with temperatures topping 50 degrees Celsius around the world. That’s 122 degrees Fahrenheit. And halfway to boiling.”
Intense heat is often less visible than other climate change impacts such as storms or floods, but it is more deadly. This “silent killer” caused about 489,000 deaths per year between 2000 and 2019, while storms and hurricanes averaged 16,000 deaths per year.
Heat waves have certainly been in the news over the last few months — too many to list. A few striking examples:
- this year’s Hajj pilgrimage to Mecca turned tragic when more than 1,300 died in a heat wave
- during the July 2024 week that set a daily global average temperature record, 30 million people in the western US were under National Weather Service heat warnings, with forecast temperatures over 110°F (43°C)
- mid-July 2024 also saw a severe heatwave spanning southern and central Europe, bringing temperatures of up to 44ºC (111.2ºF) to parts of Spain, while spawning forest fires in Greece and Croatia
- Climatologist and Weather Historian Maximiliano Herrara posted in July 2024 (@extremetemps) “Record heat is sweeping all the world, except [a] few European countries and a couple in the Southern Hemisphere, all countries have broken records this month”
- July 19, 2024, Daily Express US reported that Iran and Dubai were particularly hard-hit, with temperatures at the Persian Gulf International Airport in Iran reaching as high as 42ºC (108ºF) with a heat index of 65ºC (149ºF). Dubai saw temperatures reaching as high as 45ºC (113ºF) and a heat index of 62ºC (144ºF)
As a result of climate warming, temperatures well above 40°C are becoming increasingly common. Over the past 12 months, even the 50°C threshold has been exceeded in at least 10 places, from Death Valley in the US (53.9°C/129.2ºF on July 7) to Agadir in Morocco (50.4ºC/122.7ºF), Sanbao in China (52.2ºC/126ºF) and Churu in India (52.3ºC/123ºF). An earlier BBC analysis found that the number of extremely hot days every year when the temperature reaches 50ºC doubled from the 1980s to 2021.
Figure 4. Daily temperatures exceeding 50C from July 2023 to July 2024 Image Credit: WMO
Climate Change is Driving Deadly Heatwaves
Heat stress is the leading cause of death from extreme weather events. One such event ravaged the US Southwest, Mexico, and northeastern Central America with extreme, persistent heat in May and June 2024. Mexico reported at least 125 deaths directly caused by the heat wave. even though the death toll from heat in this sort of event is typically under-reported.
An international study, led by the World Weather Attribution (WWA) team, analyzed the event to assess the extent to which human-induced climate change altered the likelihood and intensity of the extreme heat. The results show that climate warming is making these events hotter and more frequent, as shown in the following graphics.
Figure 5: The increase in the frequency of heatwaves in a warming climate.
As illustrated in Fig. 5, in the pre-industrial period, before anthropogenic climate change, heatwaves similar to the 2024 event were rare—a 1 in 525-year occurrence. By 2024, with long-term average climate warming at 1.2°C, similar heatwaves have become a 1 in 15-year event. At projected levels of climate warming, we should reach 2°C of warming by about 2060, by which time an extreme heatwave in this part of the world will be a 1 in 4-year event. Similarly, 5-day heatwaves in this region are becoming progressively hotter under climate change, as shown in Figure 6, below.
Figure 6: Increase in severity of extreme heat events due to climate change
Social and Economic Impacts
A new report by the International Labor Organization (ILO) finds that over 70 per cent of the global workforce (2.4 billion people) are already at high risk of extreme heat, resulting in 22.85 million injuries and 18,970 deaths annually. In addition, as daily temperatures rise above 34°C (93.2°F), labor productivity drops by 50 percent.
But we know that it will continue to get hotter still. As climate warming continues in the coming decades, some regions of the world will become literally uninhabitable as temperatures exceed human limits. Based on projected warming by 2100, IPCC Assessment Report 6 predicts that Central and South America, southern Europe, Southern and Southeast Asia, and Africa will feel the greatest impact on heat-related mortality. Crucially, the IPCC finds that peak temperatures in heatwaves will increase significantly faster than global mean and local average temperatures. As the WWA analysis of the 2024 heatwave in the US Southwest, Mexico, and Central America showed, both the likelihood and intensity of extreme heat events will increase alongside future climate warming.
Half the world’s population lives in cities, and cities are growing faster than the rest of the world.
Figure 7: Cairo, Egypt Image Credit: Simon Matzinger CC-BY-3.0
Extreme heat is also having devastating impacts on the global economy. One key impact is decreased worker productivity. When temperatures rise above 24-26°C (upper 70’s F), labor productivity begins to fall. By 35°C (95°F), productivity drops by 50 per cent. By 2030, economic loss due to heat stress at work in a warmer climate is estimated to reach $2.4 trillion, up from $280 billion in 1995.
Naturally, hotter weather increases demand for cooling—air conditioners, refrigerators, freezers. A 2023 UN Environment Programme (UNEP) report found that cooling accounts for about 20% of global electricity consumption. and it’s a major driver of additional generation capacity to meet peak demand. The UNEP report forecasts that the global installed capacity of cooling equipment will nearly triple by 2050, doubling electricity consumption. Greenhouse gas emissions from cooling are predicted to increase, accounting for more than 10% of projected global emissions in 2050.
The key takeaway from our quick overview of extreme heat is that it will get much worse than it is today.
We are locked in to at least another 1.5°C of global warming (to a total of 2.7°C above preindustrial levels)—if we meet our current commitments to the Paris Agreement. That’s a big “if.” We need to recognize that tomorrow’s extreme heat will be worse and take the actions necessary to adapt to that hotter world now, before it’s too late.