亚开行-极端高温_新兴科学及其对亚太地区的影响（英）-2025.12_82页_2mb

Summary of "Extreme Heat: The Emerging Science and Its Implications for Asia and the Pacific"

Core Content

This working paper explores the increasing frequency and severity of extreme heat events in Asia and the Pacific, highlighting the scientific developments and implications for policy and investment. It emphasizes the need for improved understanding, monitoring, and adaptation strategies to address the growing risks associated with extreme heat.

Main Points

1. Context and Definitions

• Focus of the Paper: The paper addresses the need for policymakers and stakeholders to understand and respond to extreme heat, which is becoming more frequent and severe.
• Definitions:
  • Heat: A form of energy transfer, often measured as high temperatures.
  • Extreme Heat: Refers to heat at the upper end of the distribution, either in relative or absolute terms.
  • Heatwave: A period of abnormally hot weather lasting from 2 days to months.
  • Marine Heatwave: A period of abnormally warm ocean temperatures relative to historical norms.
  • Heat Stress: The condition where the body accumulates heat and cannot release it effectively, leading to health risks and reduced productivity.
  • Uncompensable Heat: A severe form of heat stress where internal heat production exceeds heat loss, causing uncontrollable core body temperature rise.
  • Urban Heat Island (UHI): Urban areas experience higher temperatures than surrounding rural areas due to infrastructure and limited green spaces.
  • Wet-Bulb Globe Temperature (WBGT): An index that measures heat stress by combining air temperature, humidity, radiative heat, and air movement.
  • Heat Index: A measure of how hot it feels to humans, combining temperature and humidity.

2. Recent Heat Extremes and Climate Projections

• Recent Events: Extreme heat has caused significant health and economic impacts, such as heat-related injuries and illnesses, school closures, and disruptions to livelihoods.
• Climate Projections:
  • Humid heat extremes are expected to increase in tropical and subtropical coastal areas.
  • At 1.5°C global warming, Shanghai's climate could resemble Karachi's from 1989–2005.
  • At 4°C global warming, many regions could see annual temperatures above 35°C for over 40 days.
  • Urban heat islands and land cover changes will exacerbate heat extremes.
  • Marine heatwaves will impact terrestrial temperatures in Pacific islands.

3. Forecasting

• Current Capabilities: Forecasts can range from short-term (hours to days) to seasonal (up to 6 months).
• Technological Advances: Machine learning, artificial intelligence, and the Internet of Things are enhancing forecast accuracy and speed.
• Challenges:
  • High-altitude areas, valleys, and small islands require tailored monitoring and modeling.
  • Real-time heat-health surveillance systems and data on worker productivity during extreme heat are needed.
• Impact-Oriented Forecasts: These can warn of critical thresholds for vulnerable groups, agriculture, energy, and water supplies.

4. Compound Extreme Heat Hazards

• Definition: Compound hazards occur when extreme heat interacts with other climate-related events (e.g., droughts, floods, cyclones).
• Examples:
  • The 2022 South Asian pre-monsoon heatwave had wide spatial impacts.
  • In Pakistan, extreme heat combined with meltwater and precipitation to cause floods.
• Implications:
  • Understanding and predicting compound events is essential for effective response.
  • Investments in regional forecasting hubs and observational networks are recommended to improve predictability and preparedness.

5. Socioeconomic and Sector Impacts

• Health: Increased risks of heat exhaustion, heatstroke, and mental and physical illness.
• Education: Heatwaves disrupt schooling, particularly affecting children from low-income families.
• Work: Outdoor worker productivity is projected to decline by over 50% in some parts of Asia by 2030.
• Food Security: Simultaneous maize crop failures in major breadbasket regions could rise from 6% to 54% with 2°C warming.
• Energy: Heat increases energy demand, particularly for cooling, and may strain power systems.
• Water and Infrastructure: Heat stress threatens water, transport, IT, and energy systems, especially in urban areas.

Key Recommendations

1. Upgrade Risk Assessment Tools: Integrate emerging science into climate risk assessments and diagnostic tools to enhance heat-resilient adaptation measures.
2. Improve Forecasts for Better Early Warnings: Develop and implement advanced forecasting techniques to provide timely warnings for extreme heat and compound hazards.
3. Invest in the Resilience of Public Services: Prioritize heat-aware adaptation measures in public services and infrastructure to protect vulnerable populations.
4. Implement Measures to Protect Workers: Ensure that institutional safeguards and investments consider worker exposure to extreme heat and promote protective measures.
5. Support Knowledge Sharing and Collaboration: Foster regional collaboration and knowledge sharing to advance heat research and support adaptation policies and investments.

Conclusion

Extreme heat is a growing threat to Asia and the Pacific, with severe implications for health, livelihoods, infrastructure, and economies. The integration of emerging science into policy and investment decisions is critical to building a heat-resilient future. The paper highlights the importance of improving forecasting, risk assessment, and adaptive measures, particularly in vulnerable sectors and populations.