FALSE: Global warming is not caused by urban heat islands

A claim that urban heat islands are the cause of global warming is FALSE.

A post on X (formerly Twitter) linked to a video that claimed that global warming is caused by the sun and urban heat islands.

PesaCheck has previously shown that neither the sun, sun spots, nor anything to do with the Earth’s orbit is the cause of global warming and climate change.

Contrary to the claim, urban heat islands do not cause global warming but contribute to it.

The urban heat island effect is a phenomenon where dense urban areas are hotter than surrounding areas. This effect can be 5–10℃ hotter. The causes of this heat include buildings trapping heat, darker surfaces and concentrated emissions absorbing heat at the surface, a lack of cooling natural vegetation, and less wind.

The effect persists at night, which causes cities to be hotter than rural areas and exacerbates heatwaves in urban areas.

A study found that urban heat islands could add half the temperature increase caused by global warming on top of it as climate change gets worse.

Urban heat islands also increase the risk of heat-related mortality associated with global climate change. The intensity of the effect depends on population size and precipitation.

African cities are also sweltering because of the urban heat island effect. In East African towns, temperature contribution to regional climate from 2000 to 2020 was 0.64℃ by day and 0.34℃ at night, an average 0.25℃ increase per decade.

This means cities are hotter: Dodoma is 1℃ hotter, Kampala up to 4℃, and Khartoum 8℃.

Africa’s rapidly increasing urban populations and development mean the continent’s cities are particularly vulnerable to the urban heat island effect.

This study showed the relationship between urban density and temperature in four African cities: Lagos, Addis Ababa, Nairobi, and Lusaka.

According to the Intergovernmental Panel on Climate Change (IPCC), humans are “unequivocally” the cause of the observed global warming of 1.1°C above 1850–1900 in 2011–2020, which continues to break temperature records and is currently behind devastating heatwaves in the Northern Hemisphere.

PesaCheck has previously shown how climate change impacts extreme weather events and heatwaves.

Almost all peer-reviewed scientific literature agrees that global warming is caused by humans, principally through the emission of greenhouse gases like carbon dioxide and methane.

The world’s science academies, including those in Africa, agree about the human origins of global warming.

Climate change is already affecting human life in a variety of negative ways, such as wildfires, floods, ocean acidification, and severe weather, among others.

PesaCheck has examined a claim that urban heat islands are responsible for global warming and finds it to be FALSE.