Intense Heatwaves Make April 2024 the Hottest on Record

Millions across South and Southeast Asia grappled with weekslong heat waves in April that continued until May. The suffocating high temperatures closed hundreds of schools in the Philippines, as the heat index reached 42°C. In Thailand, temperatures have broken record nonstop for 13 months, and Vietnam heatwaves have brought intense droughts in the south (Chen, 2024).

April and May are usually the hottest months in the Philippines and other Southeast Asian countries. Still, this year, the El Niño event has worsened the situation, bringing hotter, drier conditions to the region.

In Thailand, at least 30 people have died due to heatstroke, while electricity demands have soared as people turn to their air conditioners. Bangkok’s temperatures reach 40.1°C, but the heat index, or what the temperatures feel like, could reach 52°C when accounting for humidity. High heat coupled with high humidity can be fatal because sweating would make it harder for the body to regulate its temperature. In Bangladesh, temperatures soared between 40°C to 42°C, forcing schools to close (Waves of exceptionally, 2024).

April 2024 is the warmest month on record

As South and Southeast Asian countries sweltered in extraordinary heat this year, new data from the Copernicus Climate Change Service (C3S) says that April 2024 is the hottest April on record. According to the European Union’s climate change monitoring service, April 2024 was 1.58°C warmer than the average temperatures in April compared to the pre-industrial period, or from 1850 to 1900.

This year’s April record temperatures mark 11 consecutive months of unprecedented temperatures from May 2023 to April 2024, with global average temperatures of 1.61°C above pre-industrial levels and 0.73°C above the 1991-2020 average.

World’s Oceans record-breaking temperature this year

A BBC analysis based on the C3S data revealed stunning information—it says the world’s oceans have broken temperature records daily over the past year. They blame this heating mostly on GHG emissions and partly on this year’s El Niño event, which worsened the warming. The BBC analysis states that the super-heated oceans have hit marine life hard and driven a new wave of coral bleaching.

The ocean is a significant buffer of climate change’s effects and a key regulator of the earth’s climate. The ocean absorbs a quarter of the carbon dioxide emissions from human activities and 90% of the excess heat from solar radiation and distributes this heat around the globe.

However, over the past year, the oceans have shown concerning evidence that they are struggling to cope with the rising sea surface temperatures (SST). Since March 2023, sea surface temperatures have been on an upward trend, reaching a new record high in August. In February and March 2024, data from the C3S shows that SST reached a global average of 21.09°C.

Human influence on sea surface temperatures

A 2023 study, “The emerging human influence on the seasonal cycle of sea surface temperature,” published in Nature Climate Change, provides direct evidence that human activities are affecting the seasonal cycle of sea surface temperature (SST), and this ocean warming is linked to carbon dioxide emission.

“This is breakthrough evidence that there is a human-caused climate change signal in ocean temperatures associated with CO2 increases,” says the study’s co-author Benjamin Santer, an adjunct scientist and distinguished scholar in the Physical Oceanography Department at Woods Hole Oceanographic Institute (WHOI) (Sea surface temperatures, 2024).

“We show that a human-caused signal in the seasonal cycle of sea surface temperature (SST) has emerged from the noise of natural variability. Geographical patterns of changes in SST seasonal cycle amplitude (SSTAC) reveal two distinctive features: an increase at Northern Hemisphere mid-latitudes related to mixed-layer depth changes and a robust dipole pattern between 40˚S and 55˚S which is mainly driven by surface wind changes,” the journal article notes (Sea surface temperatures, 2024).

The authors claim their finding disproves claims that recent temperatures are natural but point out the human influence on the changes in the ocean’s seasonal temperatures, which has a “wide-ranging impact on marine ecosystems,” says co-author Dr Jia-Rui Shi, a Postdoc with Woods Hole Oceanographic Institute (WHOI). Shi adds, “Gaining insight into the anthropogenic influence on seasonality is of scientific, economic, and societal importance” (Sea Surface Temperatures, 2024).

Impacts of ocean warming

The BBC article highlights the impacts of ocean warming, from sea life to accelerating sea level rise and fuelling extreme weather events.

Warming of the oceans will considerably impact global sea life, such as the mass bleaching of coral globally. Corals serve as ocean nurseries to a quarter of all marine species and are a critical element in the ocean ecosystem.

Sea ice collapse due to ocean warming seriously affects the emperor penguins. Prof Mike Meredith from the British Antarctic Survey says, “There have been examples of the sea ice collapsing before emperor chicks have properly fledged, and there have been mass drowning events” (McGrath et al., 2024).  

Warmer seas give tropical storms extra energy, which could help fuel a potentially damaging hurricane season.

Warming oceans accelerate ice sheet melt, fuelling sea level rise for centuries. Deep ocean warming is also one of the aspects of global warming that is committing us to centuries and millennia of climate change, says Angélique Melet, a researcher with Mercator Ocean International.