Top 5 Countries in Asia Pacific Most Affected by Climate Change

There is no doubt that human-caused climate change has contributed to an increase in extreme weather events, rising temperatures and sea levels and an increase in species extinction. While climate change has affected every nation in some way, Southeast Asia has taken the brunt of the impact. But which country in particular has suffered the most from the climate changes of the 20th and 21st centuries? By looking at historical and 20-year projections of climate metrics of 12 countries in Asia Pacific, we found out which nations were impacted the most.

Study Highlights

1. Vietnam

Vietnam's relationship with climate change has been a turbulent one, which cemented its number 1 position. Looking at historical changes, Vietnam saw one of the greatest increases in average annual temperature and sea level changes. In the 100 years between 1916-2016, Vietnam's annual temperature increased by 1.27°C and continued to increase further to an average temperature of 25.21°C in 2019. The annual average sea level between 1993-2015 had a 14% greater increase than the average increase for the 12 countries analysed. Not only that, it had the second worst 10-year Climate Risk Index (CRI) (a score that calculates economic and human loss due to weather-related events) and is at above average risk for sea level changes, temperature changes and droughts in the next 20 years.

In the near future, Vietnam is projected to see an above average increase in temperature, drought likelihood and rainfall. This movement towards more extreme seasonal changes may necessitate allocating more resources to improve water supply during drought periods and flood barriers. Furthermore, Vietnam's agricultural and fishing industries—which make up 14% of its GDP—may be further disrupted and result in a significant impact on Vietnam's economy. The redistribution of economic resources towards disaster mitigation and the looming threat of agricultural loss poses a considerable threat for a country that, despite making great economic progress, still has one of the lowest GDP per capita (PPP) out of the countries analysed.

2. Thailand

Thailand came in as the 2nd country that has been most affected by climate change due to a riskier Climate Risk Index (CRI) score, above average temperature increases and projected increases in inclement weather. Its 10-year CRI was the 3rd worst on our list, indicating that Thailand suffers considerable economic and human losses due to weather-related events. Looking at historical data, Thailand's temperature increased by 1.59°C in the 100-year period between 1916 and 2016—30% more than the 12 country average. Furthermore, out of the countries that started with an average annual temperature of around 25.5°C, Thailand is the only one that topped 27°C in 2016. This increase in heat implies that Thailand will have more days per year that require the use of cooling equipment (such as AC's), which will in turn increase energy consumption costs and increase health risks associated with extreme heat.

In addition to the rising temperatures, Thailand is also at risk for an increasing number of severe weather events that can affect its delicate agricultural system. In addition to rising sea levels, Thailand is expected to have an above average increase (5mm-17.54mm) in 5-day periods of rainfall, meaning that rain showers will get more severe and increase the chance of flooding. This is coupled with a 5-6% increase in the likelihood of severe annual droughts compared to its long-term average, leading to drier dry seasons and wetter wet seasons. This increase in seasonal extremes can increase the risk of Thailand's main agricultural staple industry (rice) to suffer, which may have a deep impact on Thailand's economy and welfare.

3. Philippines

In 3rd place is the Philippines, due to having the riskiest 10-year Climate Risk Index score, above average annual temperature and sea level rises along with increased likelihood of severe weather. With temperature change accelerating worldwide, the Philippines (which is known for its tropical, rain-heavy climate and high exposure to severe weather events like cyclones, floods and droughts) will have to contend with costlier and more dangerous storms, droughts and heatwaves. Higher sea levels will cause storms to move further inland, causing more destruction and also increasing inland flooding. In 2018, the Philippines felt the effect of Typhoon Mangkhut, which was the most powerful typhoon recorded worldwide and in 2019, Philippine's 6 severe weather events resulted in at least a $3.35 million economic loss per capita, one of the highest losses recorded out of the 12 countries analysed.

Looking at the data, the Philippines had one of the highest average annual temperature increases of 1.45°C over the past century. We also found that its average annual rainfall increased the most out of our 12 countries—11% in the period from 1981-2000 to 2001-2016. Future projections also indicate that the Philippines will see increased levels of 5-day rainfall, which will work in tandem with rising sea levels to increase the chance of floods. Furthermore, despite a lower temperature increase in the next few years compared to other Asia Pacific countries, the probability of experiencing a heatwave in a given day is 10% above long-term average in the next 20 years. Overall, climate change has had a considerable impact on multiple sectors of the Philippine economy, including energy consumption, infrastructure, agriculture and healthcare.

4. India

India comes in 4th place in terms of how much it's been affected by climate change. Overall, India has one of the lowest CRI scores mostly due to the large economic and human losses sustained because of periods of extreme heat, monsoons, cyclones and flooding relative to its human development index and per capita GDP. Furthermore, with nearly 75% of India's population relying on farming or rural income, extreme weather events and changes in soil due to global temperature changes can have devastating effects on a large portion of India's population.

Looking at historical data, India experienced an average annual temperature increase of 1.15°C and a rainfall decline of 13% between 1916-2016. The increasing temperatures contrasted with a decline of annual rainfall is a worrying sign. With a projected average monthly rise in temperatures between 0.85°C-1.01°C in the next 20 years, India will be at risk of increased number of heatwaves and droughts. This increase in dry, hot conditions can be disastrous since India's drought-prone regions are also the ones that are currently used for agriculture. At the same time, India is also projected to have the highest increase in 5-day rainfall maximums in the next 20 years, indicating that multi-day rainstorms will produce more rain in India's wetter regions and increase chances of flooding.

5. Australia

Australia is the only country in the top 5 that is considered a high-income nation. However, it secured that place because it has the 5th worst 10-year CRI score, above average temperature increases and is in 1st place for drought probability in the next 20 years. In 2019, Australia saw 6 of its hottest days on record, with temperatures reaching 49.9°C. The dry heat and lack of rain contributed to fires leading to an economic loss of $5.095 billion dollars, and added to Australia having the greatest economic loss per capita due to severe weather events.

Compared to other countries on our top 5, Australia has seen comparatively small historical changes in its temperature and precipitation. Australia's historical temperature and rainfall changes were below the average of the countries analysed. However, as climate change continues, Australia may end up getting severely impacted. In the next 20 years, average temperatures are expected to increase between 0.91°C-1.07°C and the probability of a severe drought will increase by 14-15%. As we've seen in recent years, the lack of rain and severe droughts has led to increased chances of costly wildfires that create widespread damage to the nation and to Australia's at-risk ecosystem. As the country that produced the most tonnes of CO2 per capita in 2019 out of the countries we analysed, Australia is the only nation on our list whose contribution to climate change has caused significant harm not just to its neighbors, but to itself as well.

Singapore & New Zealand Were the Least Impacted, But Weren't Immune to Climate Change

Singapore was the least affected out of all 12 countries. Its lack of catastrophic weather events and high GDP per capita show that Singapore was spared the financial and societal damages other countries experienced due to climate change. Furthermore, Singapore scored below our 12 country average on most historic and projected climate-related changes like sea level rise, temperature changes and rainfall. Still, heat and rising global sea levels will be the greatest climatic threat to Singapore. There is an 11-18% increased chance of Singapore experiencing a heatwave and a 10-15% increased chance of experiencing a drought. These startling figures are what pulled Singapore's climate projection ranking to 2nd place. Thus, while Singapore may not necessarily suffer the same catastrophic weather events as other Asia Pacific nations, the nation may still have to allocate more resources towards battling rising heat and sea levels in the years to come.

New Zealand was also spared the extreme weather events other countries on our list have experienced due to protective effects of the Southern Ocean, so economic and human loss has been relatively minimal. Furthermore, New Zealand's climate hasn't changed as much as the other countries we analysed. Historical data indicates that New Zealand saw below average temperature and annual precipitation changes (both century and 30-year average). In the near future, New Zealand's rainfall, temperature, drought and heatwave changes are also expected to be below average.

Correlation Between Economic Development & Climate Change Impact

Ironically, most of the nations that have suffered the most and will continue to get the brunt of climate change's impacts are developing nations. This is evident by looking at the Climate Risk Index, which shows developing nations typically suffer greater economic and human losses due to weather-related events. These countries also have a heavier reliance on the very things that climate change is threatening, like farming and fishing. Furthermore, as these countries re-allocate their resources towards mitigating the effects of climate change, there will be less funds available for areas such as infrastructure, employment, education and healthcare—all the things that can help nations prosper. With less funds in government budgets allocated to improving the livelihoods of their citizens, large portions of the population may end up bearing the greatest burden of climate change and be forced to either migrate or attempt to make do with an increasingly changing climate.

Methodology & Limitations

We explored how climate change has affected 12 Asia Pacific nations in our lifetime by looking at historical changes and near-future projections (2020-2039). To do so, we used the 10-year Climate Risk Index (CRI) to find the average 10-year economic and human losses associated with severe weather patterns caused by climate change, historical changes and future projections of several climate measurements including temperature, sea level and rainfall changes. Because all these countries have different climates, we ranked countries based on a weighted average that was 33% CRI index (economic/human loss due to climate change), 33% historical climate changes and 33% near-future climate projections. We then looked at how each country compared to the others on our list. Please note that when we refer to averages (i.e. temperature changed above/below average), we are referring to the average of the countries analysed, not global average.

We also want to emphasize that the raw rankings were within a couple of points across the board, which shows that every country on this list has been impacted by climate change. For instance, while Singapore may have come in last on this list, that does not mean it hasn't seen its fair share of difficulties from the changing climate— it just means that other countries have had it worse. Lastly, climate change is an incredibly complex issue that takes decades to comprehensively study. Because of this, our study is not intended to advise on policy issues. For more information about the metrics we used, please find the sources linked below.

Category 1: Climate Risk Index

The Climate Risk Index is an index compiled by Germanwatch that aims to identify which countries suffered the most economic and human damage by weather-related events. To look at overall changes, we used the 10-year average score that took into account years between 1999 and 2018. Below are the scores for the countries we analysed. The lower the score, the greater the country has been impacted by weather-related loss events.

Sub-Category 1: Economic & Human Weather-related Loss

Category 2: Historical Metrics

Historical metrics included average sea level anomaly (1993-2015), historical temperature and rainfall data (1901-2016). The average sea level anomaly measures changes in the average annual sea-level compared to the long-term average (LTA). For instance, an anomaly measurement of 15mm indicates that the sea level rose 15mm compared to average levels recorded over a long period of time. In this study we measured the difference in the average annual sea level anomaly in 1993 and 2015. Historical temperature changes ranged between 1901 and 2016 and we looked at both 100-year changes and changes in periods of 20-30 years to ensure we weren't measuring temperature changes based on one-off annual changes. Since rainfall varies year to year, we measured changes in the 20-year average of the years 1901-1920 and 2001-2016. To see more recent trends, we also considered average rainfall changes between 1981-2000 vs 2001-2016.

Subcategory 2: Historical Climate Metrics

Category 3: Climate Change Projections

Near-future metrics measured annual changes for monthly temperature, probability of heat waves and drought, cooling power demand and expected 5-day rainfall maximum (25-year return level). An anomaly measures the change from the long-term average or baseline point, which for these metrics is the long-term average measured for the years 1986-2005. For instance, if the measured anomaly for the likelihood for a drought between the years of 2020-2039 is 0.14, it means that the chance for a drought is 14% greater compared to the years between 1986-2005. These metrics were used because they help predict severe weather events. For instance, sea level rise and increased rainfall usually contribute to flooding as water moves inland and rain gets more intense. More specifically, the 5-day cumulative rainfall episodes over a given period of years measure the maximum amount of rainfall in that period when rain showers last longer than a day. When this increases, there is a greater chance of flooding. Droughts and heatwaves may contribute to an increase in wildfires and a destruction of fertile, agricultural soil.

The range used was based on low-emission (RCP 2.6) and high emission (RCP 8.5) projections. These emissions are predictions based on the level of global greenhouse gas concentrations. RCP 2.6 is the peak scenario that requires CO2 emissions to start declining by 2020 and reduce to 0 by 2100, methane emissions reduce to half of the levels of 2020 and the sulphur dioxide emissions decline 10% of 1980-1990 levels. This scenario is likely to keep global temperatures from rising above the critical 2 degree threshold by 2100. RCP 8.5 projections expect emissions to continue to rise in the next 100 years. It is the worst-case scenario for climate change projections. Since there are many climate models, we used the World Bank's Ensemble (50th percentile), which returns the median values of all the climate models.