Climate Change–Induced Impacts on PM2.5 in Taiwan Under 2 °C and 4 °C Global Warming

 

1. Meaning

“Climate change–induced impacts on PM2.5 in Taiwan under 2 °C and 4 °C global warming” refers to how future climate conditions caused by global temperature increases will change the levels, patterns, and behaviour of PM2.5 pollution in Taiwan.
PM2.5 (fine particulate matter ≤ 2.5 micrometers) is dangerous because it penetrates deep into the lungs and bloodstream.

The study investigates:

• How PM2.5 will change when global temperatures rise by 2°C and 4°C.

• Which seasons and regions in Taiwan will be more affected.

• How climate-driven changes in wind, rainfall, humidity, and atmospheric stability influence PM2.5.

2. Introduction

Taiwan faces persistent air-quality challenges due to its topography, dense population, industrial zones, and seasonal monsoon patterns. PM2.5 pollution is especially harmful because it causes cardiovascular, respiratory, and developmental health issues.

With global warming progressing, climate conditions such as temperature, rainfall, wind speed, boundary-layer height, and long-range transport are changing. These changes can either worsen or reduce air pollution depending on the season and region.

To prepare for the future, scientists model how PM2.5 might behave under 2 °C (Paris Agreement upper limit) and 4 °C (high-emission pathway) global warming. These findings help Taiwan design climate-resilient air-quality policies.

3. Advantages (Positive Outcomes / Potential Benefits)

Although climate change mostly worsens PM2.5, some potential advantages exist:

3.1 Improved PM2.5 in Some Warm Seasons

• Increased rainfall and strong convection during summer may help wash out pollutants, lowering PM2.5 in some regions.

3.2 Stronger Scientific Understanding

• Modeling under different warming levels improves predictions and guides data-driven environmental planning.

3.3 Better Policy Preparation

• Understanding climate–pollution interactions helps Taiwan develop early warning systems, targeted control measures, and winter-season strategies.

3.4 Integration of Climate and Air-Quality Planning

• Encourages coordinated climate mitigation and air-pollution control policies.

4. Disadvantages (Negative Impacts)

4.1 Increased PM2.5 in Winter

• Taiwan is projected to see higher winter PM2.5 levels, especially under the 4 °C scenario.

• Stagnant weather, weak northeastern monsoon winds, and lower atmospheric mixing worsen pollution.

4.2 Higher Health Risks

• Increases in cardiopulmonary disease, asthma, lung cancer, and premature deaths.

4.3 Regional Inequality

• Western and southern Taiwan (Taichung, Changhua, Yunlin, Kaohsiung, Pingtung) experience more severe deterioration.

4.4 More Frequent High-Pollution Episodes

• Longer periods of stagnant air and fewer rain events increase smog episodes.

4.5 Greater Energy Demand

• Hotter weather increases electricity usage (AC demand), indirectly increasing emissions if fossil fuels remain dominant.

5. Challenges

5.1 Complex Weather–Pollution Interactions

Climate effects on PM2.5 depend on many changing factors:

• Wind direction & speed

• Humidity

• Cloud cover

• Temperature

• Regional transport from China

5.2 Difficulty in Predicting Local Emission Changes

• Taiwan’s future industrial policies, energy transition, and vehicle electrification rates also affect PM2.5.

5.3 Uncertainty in Climate Models

• Different global climate models predict slightly different warming patterns.

5.4 Cross-Border Pollution

• China’s pollution transported during winter monsoon will interact with climate conditions, making impacts harder to isolate.

5.5 Policy Implementation

• Taiwan must coordinate central and local governments to respond to climate-driven pollution increases.

6. In-Depth Analysis

6.1 Winter Deterioration

Both 2°C and 4°C warming increase winter PM2.5 due to:

• Lower boundary-layer height → pollutants trapped near the ground

• Weaker monsoon winds → less dispersion

• More stagnant days

• Reduced rainfall → fewer clean-out events

• More stable atmosphere → pollution accumulates easily

This effect is stronger under 4°C warming.

6.2 Seasonal Differences

• Summer: Higher rainfall and stronger convection may lower PM2.5.

• Winter: Significant increases due to stagnant air.

6.3 Regional Impacts

• Most affected: Western Taiwan, especially Taichung, Yunlin, Chiayi, Tainan, Kaohsiung.

• Reason: Basin-like geography, industrial zones, and wind shadows of the Central Mountain Range.

6.4 Chemical Formation Changes

Climate change can alter:

• Secondary aerosol formation

• Chemical reactions influenced by humidity and temperature

• Organic aerosol production

6.5 Climate Mitigation Benefits

Limiting global warming to 2°C instead of 4°C significantly reduces the climate-driven rise in PM2.5.

6.6 Health Burden Increase

Higher winter PM2.5 will lead to increases in:

• Cardiovascular mortality

• Respiratory diseases

• Hospital admissions

• Early mortality among the elderly and children

7. Conclusion

Climate change will significantly influence Taiwan’s air quality. Under 2°C and especially under 4°C global warming, Taiwan is expected to experience higher PM2.5 levels, particularly in winter and in western/southern urban regions. While summer may see slight improvements due to more rainfall, the overall effect is negative.

This highlights the urgent need for:

• Climate mitigation (limit global warming)

• Winter-focused air quality strategies

• Stronger emission-control policies

• Advanced forecasting systems

Understanding these impacts allows Taiwan to better protect public health, improve air-quality management, and plan climate-resilient policies.

8. Summary 

Climate change is projected to worsen PM2.5 pollution in Taiwan, especially during winter, due to stagnant air, weaker monsoon winds, and reduced atmospheric mixing. Western and southern regions will face the most severe impacts. While some summer improvements may occur, the overall effect is negative. Limiting global warming and strengthening winter emission controls are essential to reduce future health and environmental risks.