Latest IPCC report predicts an increased risk of heatwaves

On 28 February 2022, the Intergovernmental Panel on Climate Change (IPCC) released a report on the impacts of climate change, adaptation, and vulnerability. [1] The report highlights several risks posed by rising temperatures, including the fact that climate change will increase the number of people exposed to heat waves as well as amplify the risks of heat extremes in cities. For instance, models indicate that between 2°C and 3°C of warming, 16 times as many people would be exposed to heat waves, rising to 36 times as many people at 4°C, causing severe risk of heat-related mortality. 

 

Africa 

 

In Africa, the risks associated with extreme heat will have severe costs for economic development and lives lost. With 1.6°C of global warming, West Africa will experience between 50 and 150 days of potentially lethal heat thresholds each year.  

Under relatively low population growth scenarios, the vulnerable population (people under 5 or over 64 years old) exposed to heat waves of at least 15 days above 42°C in African cities is projected to increase from around 27 million in 2010 to 360 million by 2100 for 1.8°C global warming and to 440 million for >4°C of global warming. [3] 

 

Asia 

 

Asian countries are experiencing a hotter summer climate, resulting in increased energy demand for cooling. [4] In Asia, the urban poor will suffer the most from extreme heat. For example, at 1.5°C of global warming, the city of Kolkata, India will experience heat equivalent to the 2015 record heat waves every year. At 2°C of global warming, Karachi, Pakistan will experience the same annual heat events. 

The IPCC noted that the occurrence of extreme heat is very likely to increase across the region. Under a scenario of 4℃ global warming in 2100, daily maximum wet-bulb temperatures are projected to exceed the limits of human survivability across most of South Asian countries. 

 

Central and South America 

 

In Central and South America, heat stress is already a concern. Most countries have already experienced between 0.8 and 15.2 additional days of exposure to heat waves in 2016-2020 compared to the past. Heat extremes are set to increase in frequency, intensity, and duration. With a global warming of 2°C, the longest annual heat wave will last more than 60 days longer than in a 1.5°C scenario. 

 

North America 

 

In North America, heat waves over land and in the ocean as well as wildfire activity are projected to intensify, and heat-related mortality and morbidity are also projected to increase. [6] According to a study published in American Geophysical Union, the demand for air conditioning in US households is projected to increase by 8% at 1.5°C of global warming, and by 13% after the 2.0°C threshold, compared to the baseline (2005–2019). [7] 

 

Europe ^[5] 

 

Heat waves are likely to become a major threat in Southern Europe, but also for Western Central Europe and Eastern Europe cities. With a global warming of 2°C, half of the European population will be at very high risk of heat stress in summer. 

Unless adequate adaptation measures are applied, highly insulated buildings that meet present building standards, will be vulnerable to overheating. In Southern Europe, cooling energy demand is projected to increase by 81-104% by 2035 and by 91-244% after 2065 compared to the period 1961-1990. In Northern Europe, of the increase is estimated to be 31-73% by 2050 and 165-323% by 2100 compared to 1996-2005. 

 

 

Sources 

[1] IPCC Sixth Assessment Report, Climate Change 2022: Impacts, Adaptation and Vulnerability. https://www.ipcc.ch/report/sixth-assessment-report-working-group-ii/ 

[2] Latest IPCC report highlights urgent need for sustainable cooling. https://www.seforall.org/news/latest-ipcc-report-highlights-urgent-need-for-sustainable-cooling 

[3] IPCC Sixth Assessment Report. Fact sheets. Africa. https://www.ipcc.ch/report/ar6/wg2/downloads/outreach/IPCC_AR6_WGII_FactSheet_Africa.pdf 

[4] IPCC Sixth Assessment Report. Chapter 10 Asia. https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_FinalDraft_Chapter10.pdf 

[5] IPCC Sixth Assessment Report. Chapter 13. Europe. https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_FinalDraft_Chapter13.pdf 

[6] IPCC Sixth Assessment Report. Chapter 13. North America. https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_FinalDraft_Chapter14.pdf 

[7] Obringer, R., Nateghi, R., Maia‐Silva, D., Mukherjee, S., Cr, V., McRoberts, D. B., & Kumar, R. (2022). Implications of increasing household air conditioning use across the United States under a warming climate. Earth's Future, 10(1), e2021EF002434. https://doi.org/10.1029/2021EF002434