Climate Change and Extreme Heat: Comprehensive Notes

Extreme Heat Events: An Overview

  • Since June 2023, record-breaking temperatures have been observed globally.
  • The pace of these extreme heat events is unprecedented, highlighting the increasing severity of climate change.
  • Cause: Climate change exacerbates heatwaves, making them longer, more extreme, and more frequent due to the increase in greenhouse gas emissions from burning fossil fuels.
  • These emissions, such as carbon dioxide, trap heat in the atmosphere, leading to global warming and more extreme weather.

Scientific Attribution

  • Attribution Studies: 93% of 152 extreme-weather attribution studies over the past 20 years indicate that human-induced climate change has increased the likelihood or severity of extreme heat events.
  • Example: The June 2024 heatwave in the US, Mexico, and Central America was made 35 times more likely and 1.4∘C1.4^{\circ}C warmer because of climate change.

Domino Effect of Heatwaves

  • Cascading Impacts: Heatwaves trigger a series of impacts, including:
    • Droughts
    • Wildfires
    • Poor air quality
    • Water and food insecurity
    • Power shortages
  • Canada Wildfires (2023): Burned 7.8 million hectares, releasing 3 billion tonnes of carbon dioxide, which polluted air as far as Europe and China, creating a dangerous feedback loop.
  • Connection b/w Heatwaves and Flooding: Extreme heat increases the likelihood of flooding; warmer air holds more moisture, and dry ground is less able to absorb rainfall.
  • Example (2022): An early heatwave in India and Pakistan contributed to devastating floods across Pakistan, India, and Bangladesh.

Unequal Impacts

  • Disproportionate Vulnerability: Developing countries and lower-income communities are more vulnerable to heat-related sickness or death.
    • Factors include location and lack of access to air conditioning.
  • Income Disparity: A 2022 study found that lower-income populations face a 40% higher risk of heatwave exposure compared to higher-income groups.
  • This inequality is projected to worsen with increasing temperatures.

Defining Heatwaves and Heat Domes

  • Heatwave Definition: An extended period of abnormally warm weather, defined in relation to a location and its historical average temperature, lasting at least two days.
  • Heat Dome Definition: Occurs when hot air becomes trapped under an area of high pressure:
    • This system acts like a lid, preventing hot air from escaping.
    • High pressure also means little to no cloud cover, intensifying the heat from the sun.
  • Example: The June 2024 heatwave in the US, Mexico, and Central America was a heat dome, making temperatures 11∘C11^{\circ}C to 16∘C16^{\circ}C hotter than normal in parts of the US.

Impacts of Extreme Heat

  • Complex Impacts: Heatwaves cause direct, indirect, and cascading impacts.
  • Mortality: Between 2000–19, there were approximately 489,000 heat-related deaths each year.
    • Excess deaths are mainly cardiovascular-related.
  • Health Exacerbation: Heat stress exacerbates underlying illnesses, increases accident risks, spreads infectious diseases, and leads to heatstroke.
  • Wildfire Smoke: Causes or worsens heart and lung diseases, increasing the risk of dementia.
  • Vulnerable Populations: Death rates are highest among elderly people, children, those with vulnerable conditions, and low-income communities.

Economic Impacts

  • Lost Working Hours: In 2019, an estimated 302 billion working hours were lost due to higher temperatures.
  • Food Security: Heatwaves negatively impact food production by reducing crop productivity and agricultural labor capacity and also worsen drought conditions, leading to food insecurity.
  • Food Prices: Production issues often lead to increased food prices, reducing dietary diversity, disproportionately affecting lower-income populations.
  • Water Supply: Water supply and quality are compromised during heatwaves, increasing the need for water for drinking, cooling, and irrigation.
  • Economic Costs: In 2022, the economic cost was forecasted to be 4.1% GDP lost for Africa, mainly from agricultural losses.
  • Workforce Risk: 70% of the global workforce is at risk of injury or death from extreme heat; in Africa, it's 93%.

Infrastructure and Energy

  • Energy Disruptions: Surges in electricity demand during heatwaves can lead to energy shortages and blackouts, which can disrupt transport, manufacturing, and citizen safety. Heatwaves also put physical pressure on energy infrastructure and can cause pieces like transformers and cable insulation to overheat.
  • Transport Disruption: Extreme heat causes metal railway lines to expand, disrupting the flow of goods and services.
  • Boreal Forests: Wildfires in boreal forests could transform them from carbon dioxide absorbers into carbon dioxide emitters.

Government Responses

  • Heat Action Plans: Many governments have implemented heat action plans to mitigate and adapt to extreme heat risks at city or national levels.
    • These plans include issuing warnings, coordinating interagency responses, preparing government and health professionals, and initiating community outreach.
  • Early Warning Systems: Crucial for informing the public about coming heat and survival strategies via radio, text messages, TV campaigns, or internet ads.
  • Shift in Focus: Heat action plans are shifting from reactive to mitigative measures.
  • Data Collection: Governments often lack the capacity to collect and analyze extensive climatological data for a granular understanding of heatwave impacts.

International Cooperation and Leadership

  • Regional Cooperation: Increasing cooperation and information-sharing between countries, especially regarding weather and climate data.
  • Chief Heat Officers: Appointing chief heat officers (first introduced in Miami in 2021) focuses on urban heat mitigation and public education.
  • Heatwave Naming: A global heat officer has piloted categorizing and naming heatwaves (e.g., Heatwave Zoe in Seville, 2023) to raise awareness.

Legislative Initiatives

  • Spain's Law: Mandates that employers adjust working conditions during extreme heat, including reducing or modifying work hours.
  • Responsibility Challenges: Determining governmental responsibility for implementation is difficult due to the multifaceted nature of the challenges.
  • Financial Needs: There is a need for funding heat resilience measures, particularly in the Global South.
  • COP28 Pledges: Despite over $700 million pledged to the loss and damage fund at COP28, climate finance is not yet reaching those most vulnerable.
  • Long-Term Solution: Reducing emissions to reduce the intensification of heatwaves.

Opportunities for Government

  • Economic Adaptation: Adapting sectors such as transport, construction, and agriculture can create millions of green jobs, fostering economic growth.

Climate Resilience in Cities

  • Urban Heat Island Effect: Exacerbated by concentrated surfaces that absorb and retain heat, combined with poor climate planning.
  • Population Growth: By 2050, around 70% of the population will live in cities.
  • Vulnerable Cities: Rapidly urbanizing cities in developing countries are more vulnerable to climate change.
  • City Initiatives: Initiatives like C40 and the Cool Cities Network and the Resilient Cities Network help cities tackle heatwaves.
  • Resilience Building: Cities need to build both social and physical resilience, including:
    • Vulnerability mapping to identify vulnerable populations.
    • Integrating natural cooling methods like urban forests, street trees, permeable surfaces, and green roofs.
  • Examples:
    • Paris and Medellin have developed ‘cool islands’ and ‘green corridors.’
    • In Madrid, a forest planted around the city’s edge to help with cooling has been calling a ‘tree cemetery’ because so many died from drought.
    • Ahmedabad in India, painted the roofs of 17,000 homes white to lower indoor temperatures.
    • Traditional architecture in Gulf countries, like narrow alleyways and internal courtyards, can help cool urban areas.

Broader Societal Impacts

  • Existential Threats: Heatwaves are existential threats that will broadly impact societies.
  • Migration and Security: Extreme heat will cause internal and cross-border migration, increasing violent crime and political instability.
  • Education Disruption: Schools may close during extreme heat to protect children (e.g., 33 million children forced out of schools in Bangladesh in April 2024), widening the learning gap between rich and poor countries.
  • Digital Infrastructure Risks: Extreme heat can cause digital infrastructure to overheat and collapse (e.g., data center failures in London in July 2022).
  • Legal Action: Young people are using lawsuits to force actions (e.g., successful lawsuit in Montana for violating the right to a clean environment).

Conclusion

  • Call to Action: Bold and decisive policies are critical to mitigate the escalating dangers of extreme heat and protect public and economic health, and to capitalize on the opportunities presented by a heat-resilient future.