The Cost of Inaction: Failing to Act on Climate Change Threatens Asia and the Pacific

Global warming is a function of the stock of greenhouse gas in the atmosphere. That stock takes time to respond to changes in the flow of emissions. For this reason, addressing most impacts of climate change in the coming decades depends on adaptation, even if mitigation is critical in the longer term.

As of mid-2024, the world’s atmospheric concentration of carbon dioxide (CO2) had reached 422 parts per million, which is 50% higher than the preindustrial level of around 280. Two-thirds of the increase has taken place since 1970 and the rate of increase has only accelerated over time. The world has not had the current level of CO2 concentrations for millions of years.

Since the middle of the 18th century, the world has emitted 1.5 trillion tons of CO2. Future CO2 emissions must be a small fraction of current levels to meet Paris Agreement climate goals, even with record global population and economic growth.

The year 2023 was already 1.46°C above preindustrial averages, and the World Meteorological Organization recently announced that 1.5 degrees of warming had been exceeded. The rate of temperature increase is also accelerating, with warming per year since 1982 three times faster than prior to that year. The 10 years from 2014–2023 were the 10 hottest years on record, and

February 2024 was the hottest month ever reported.

Over longer timeframes, the impacts of climate change are conditioned by whether the world acts in line with Paris Agreement goals of limiting warming to well below 2°C above preindustrial levels and to pursue efforts to limit it to 1.5°C. Yet, even if strong action were taken, the climate will continue to warm for decades.

Under currently implemented policies, warming of around 3°C is expected by 2100, not accounting for natural processes like thawing permafrost or warming oceans that could release more greenhouse gases and further increase temperatures.

Signs are emerging that the world could be reaching tipping points that can trigger these feedbacks. Tropical forests and peatlands have historically been major carbon sinks. However, increasing forest fires are releasing the stocks of CO2 that forests have stored and peatlands are emitting methane, turning them into emissions sources.

In 2023, ecosystem sequestration of carbon slowed substantially. If natural emissions sinks continue to transform to emissions sources, high levels of warming may become impossible to avoid, and the world may end up on track to warming similar to what modelers have termed a high-end emissions scenario, rather than only 3°C of warming.

The evidence is clear that even current levels of greenhouse gases are already transforming our world in drastic and irreversible ways.

Were that to happen, the most dramatic changes will be heat waves. Historically, each year, Southeast Asia has had 20 days or fewer with the regional temperature at more than 35°C. Under 4.7°C of mean global warming, such days would exceed half a year by 2100. South Asia would have days exceeding 35°C rise from around 100 to about 200 days annually by 2100, East Asia from around 7 to nearly 50, and Central and West Asia from 10 to around 50. This would diminish labor productivity by up to 30% in high exposure sectors, while driving large increases in energy consumption for cooling.

Extreme storm events across Asia and the Pacific would increase in severity. From 1979 to 2016, cyclones in East Asia and Southeast Asia had a duration that grew by two hours to nine hours after making landfall, and they traveled around 100 kilometers further inland. Under a high-emissions climate scenario, continuation of this pattern would lead to a doubling of the destructive power of cyclones in Asia and the Pacific by 2100, which is much higher than the change expected globally.

Sea level would rise by about 0.8 meters globally by 2100 under a high-end emissions scenario. Observed sea-level gauges show rates of relative sea-level rise in certain areas of Asia and the Pacific that are about double the global average, and internal climate variability is expected to amplify climate change effects in the region to well above those experienced globally.

Instability at the Arctic and Antarctic creates additional uncertainty about the degree of sea-level increase, as accelerated melt of polar icecaps can increase this further. Under scenarios of sea ice instability, around 300 million people in Asia and the Pacific live in areas threatened by coastal inundation.

Models reveal trillions of dollars in capital damage each year by sea-level rise, storm surges, and coastal flooding in Asia and the Pacific by 2070 under a high-end emissions scenario. The largest long-term damages are expected in the largest economies, while affected populations are concentrated in the People’s Republic of China, India, Bangladesh and Viet Nam. Affected populations triple by 2050 and reach over 50 million annually by 2070. Damages rise by many times to reach a median value of $3 trillion annually by 2070.

Intensified and more variable rainfall, along with more extreme storms, would bring increasing landslides and floods. This will be caused by overflow of rivers and from intense rainfall leading to water stagnation. Leading models also show trillions of dollars of annual capital damage from riverine flooding in Asia and the Pacific by 2070, with 110 million people potentially affected on average each year under a high-end emission scenario.

Climate effects on agriculture, fisheries, and forestry will disproportionately affect poor and vulnerable communities. Most poor people in the Asia and Pacific region depend on agriculture for livelihoods, and food accounts for most of their consumption, so climate-related impacts on the sector will disproportionately harm the most vulnerable.

The effects on the economies of Asia and the Pacific could be profound.  We find in our recent modeling that impacts of climate change under a high emissions scenario, counting from a 2020 base would lead to 17% GDP loss in the region by 2070. The overall number masks heterogeneity in the region, as vulnerable countries could lose up to 30% of GDP. By 2100, those relationships suggest that 41% of GDP could be lost at the regional level, with vulnerable countries losing up to 78% of GDP.

These are only the more understood risks. The unknown risks of climate change to ecosystem integrity, ecosystem services, and climatic stability could cause losses to be far higher. The evidence is clear that even current levels of greenhouse gases are already transforming our world in drastic and irreversible ways.

Ignoring this reality not only accelerates warming but also deepens the vulnerability of billions of people, especially in regions like Asia and the Pacific, where rising seas, extreme weather, and agricultural impacts could devastate lives and economies.

Every day that we do not act will only make these impacts worse.

This blog post is based on research for the 2024 Asia-Pacific Climate Report.