Extreme temperature

Over the past decades, population exposure to heat stress has increased significantly. This is alarming for at least two reasons: the potential impact this will have on human health and the economic costs involved in dealing with it.

The share of IPAC population exposed to hot summer days has grown every year, with an estimated 17% more people exposed to hot summer days in 2021 compared to 1979 (see Figure 14). Countries whose population was most exposed to heat stress include: Saudi Arabia (90.9%), India (69.7%) and Türkiye (10.3%).2

Southern Europe is also significantly affected, with Greece, Italy and Spain experiencing more than 60 days of exposure per year to strong (or worse) heat stress between 2017 and 2021 and these countries are also experiencing more than 10 additional days per year of strong (or worse) heat stress exposure compared to the reference period 1981-2010. The hot European summers are here to stay, with the recent wave in France and England in 2022 highlighting once more the urgency of taking appropriate measures to tackle extreme heat.

Similarly, Indonesia, India and Saudi Arabia are experiencing increasing exposure to heat stress of more than 250 days of strong (or worse) exposure per year. For example, in Saudi Arabia, there have been an additional 11 days per year of strong (or worse) heat stress exposure compared to the reference period 1981-2010. In India alone, heat stress exposure between 2017 and 2021 affected approximately 1.35 billion people, highlighting the serious risks associated with heat stress in certain countries.

Moreover, in 21 countries ‑ of countries covered under IPAC ‑ more than 10% of their populations were exposed to an increasing number of tropical nights over 2017‑21. This included extreme examples, such as India and Saudi Arabia, where more than 95% of its population is being exposed to tropical nights highlighting the urgency to adapt to climate change and increase mitigation efforts.3

 

Figure 14. Over 60% and increasingly the population is exposed to hot summer days across IPAC countries

Percentage of population exposed to hot summer days (Tmax > 35°C) across the IPAC region, 1979 – 2021

Source: (Maes et al., 2022[37]).

 Extreme precipitation

Increasing temperatures combined with extreme rainfall means countries dependent on agriculture production may be extremely vulnerable. A majority of IPAC countries are experiencing a substantial number of days with extreme precipitation events (compared to the reference period 1981-2010). In 2021, croplands were especially exposed in several western and northern European countries, such as Belgium, Latvia, the Netherlands, Sweden and Switzerland. IPAC countries with the highest share of croplands exposed to extreme precipitation4 include Indonesia (25.5%), Peru (11.9%) and Colombia (11.1%).

The economy of countries dependent on the agricultural sector is highly vulnerable to extreme precipitation. Six out of ten countries considered most dependent on the agriculture, forestry and fishing sector are also among the most exposed to extreme precipitation of more than one week per year. For example, the GDP share of the agriculture, forestry and fishing sector in Indonesia and Colombia is approximately 13.3% and 7.1%, respectively, highlighting that some countries’ GDP may be more exposed to extreme precipitation events than others (Figure 15). This could lead not only to lower incomes and risks to food security but also to possible dramatic changes in migration flows.

 

Figure 15. Some countries’ GDP is more exposed to extreme precipitation than other countries

Average annual percentage of cropland exposed to extreme precipitation events and share of GDP from Agriculture, forestry and fishing sector, 2017-21.

Note: Gross Domestic Product (GDP) values represent the average GDP value from Agriculture, forestry, and fishing over the period 2017‑ 2021 (OECD, 2022). These GDP values may overestimate agricultural GDP since it includes forestry and fishing. GDP values for Peru are derived from the World Bank national accounts.

Source: (Maes et al., 2022[37]).

 Extreme droughts

Croplands are also increasingly affected by extreme droughts. Across the IPAC region, there has been a significant decrease in soil moisture on croplands over the last four decades. Countries most affected by agricultural droughts include Argentina and South Africa, which experienced a decline of more than 6% on average in cropland soil moisture in the past five years. (Figure 16).

Drought on croplands also differs widely across regions within countries. There are increasing drought conditions on croplands for almost 70% of OECD large regions, such as the United States and Europe, where cropland soil moisture has been lower in the past five years.5 In three OECD countries, certain subnational regions recorded a drop in soil moisture of more than 10% on average over the past five years compared to the reference period 1981‑2021, including Chile, Portugal and the United States.

 

Figure 16. Worsening drought conditions on croplands across the IPAC region

Cropland soil moisture anomaly over the period 2017-21 compared to the climate normal period 1981-2010

Note: Iceland is not included in the IPAC aggregate because of data unavailability.

Source: (Maes et al., 2022[37]).

 Wildfires

Wildfires are also increasing and concentrating in specific countries and regions, with disastrous results. For example, 20% of global burned land occurred in ten IPAC countries between 2017 and 2021. This poses a problem for those countries and affects global mitigation efforts. Of the ten countries identified, three are high-income economies (Australia, Canada and the United States), six are upper‑middle‑income economies (Argentina, Brazil, China, Colombia, Mexico and South Africa), and one is a lower‑middle-income economy (India), suggesting wide disparities in terms of labour constraints, financing needs, wildfire policy implementation and coping capacity.

On average, approximately 1.2 million square km, which is roughly equivalent to the size of South Africa was burned per year between 2017 and 2021 in the most affected countries -Argentina, Australia, Brazil, Colombia, India, Portugal and South Africa.

Exposure to wildfire is significant and widespread. It risks the destruction of ecosystem services, notably biodiversity and carbon capture, as well as human life. Approximately 10% of the population in India, Mexico and South Africa, and 5‑10% of the population in Chile, Costa Rica and Israel live in areas with a very high wildfire danger. An annual average of 62% of the population in South Africa and 44% of the population in Australia were exposed to very high wildfire danger between 2017 and 2021. India’s population is the most exposed: in 2021 alone, 160 million people were living in areas with a very high wildfire danger (see Figure 17).

Across the IPAC countries, there is an overall increase in forest exposure to very high or extreme wildfire danger (Figure 17). For example, Brazilian forests have around 2 million km2 exposed to wildfire danger over the past five years. Other countries such as the United States, Australia and Mexico also have considerable amounts of forest exposed, with 894 000 km2, 701 000 km2 and 632 000 km2 of forest areas exposed to very high or extreme fire risk, respectively. The high amounts of forest exposure highlight the considerable wildfire risk forests face and should be treated with urgency given the key role forests play in climate change mitigation measures around the world.

 

Figure 17. Meteorological changes increase forest exposure to wildfire danger

Annual percentage of forested areas exposed to very high and extreme fire danger for more than three consecutive days, 2000-21.

Source: (Maes et al., 2022[37]).

 Wind threats

Climate change can also cause extreme events such as storms, which not only lead to the loss of human life, but can destroy economic infrastructure, increasing the costs of loss and damage, as well as future replacement and construction. Over the past two decades, built-up area exposure to violent storms remains consistent across the IPAC region (Figure 18). Countries most exposed to violent storms are located principally in northwestern Europe and eastern Asia. Countries such as Belgium, Iceland, Ireland, the Netherlands and the United Kingdom had more than 80% of their population and built-up areas exposed to violent storms in 2020, highlighting the importance of accounting for wind threats as a climate‑related natural hazard (Figure 18).

Meanwhile, exposure to tropical cyclones is limited to a subset of IPAC countries due to their geographic position. The most exposed IPAC countries are Japan, Korea and Mexico, where more than 60% of their populations and built-up areas are exposed to tropical cyclones (with wind speeds higher than 119 km/h or 33 m/s). Japan is the country most exposed to violent storms, with almost 80% of its population exposed to cyclones of Category 3 or higher (with wind speeds higher than 178 km/h).

 

Figure 18. Wind threats due to violent storms or cyclones vary widely between IPAC countries

Share of built-up area exposed to (a) violent storms or worse for the IPAC region, 2000-21, (b) cyclone categories in 2020 with a 100-year return period

Note: Wind gust (km/h) data with a 100-year return period were first converted to sustained wind speed and separated into cyclone categories using the Saffir-Simpson scale.

Source: (Maes et al., 2022[37]).

 River flooding

The recent floods in Pakistan in September 2022 were dramatic. Early estimates suggest that one‑third of the country was under water and at least two-thirds of the country was affected, displacing 33 million people and causing more than 1 200 causalities (Mallapaty, 2022[47]). These events are a reminder of how river flooding can affect people’s lives directly and cause substantial economic losses by damaging infrastructure, settlements and agricultural lands. Of the 51 IPAC countries under review, the Netherlands and Hungary have around 20% of total land area exposed to extreme river flooding. Meanwhile, 18.6% of China’s built-up area is exposed, followed by Latvia (16.1%), and Croatia (12.7%) (Figure 19). In terms of agricultural land exposure, the most affected IPAC countries are Hungary, the Netherlands, and the Slovak Republic with more than 17% of their cropland exposed to possible extreme events.6

River flooding can also cause significant human losses. Among the IPAC countries, populations in Latvia and the Netherlands are the most exposed, with more than 24% of people potentially affected, followed closely by China (21%) and India (17%). These last two countries also experienced the largest increase in population exposure to river flooding, with an additional 3 million and 5.3 million people exposed, respectively, in 2015 compared to 2000.

 

Figure 19. Built-up area exposure to river flooding varies between IPAC countries

Top 10 IPAC countries with share of built-up area exposed to river flooding with a 10-year return period in 20201

Note: Grey line is the IPAC average built-up area exposure to river flooding. A return period is the average or estimated time that a specific climate-related hazard is likely to recur.

1.

10-year period refers to the period of a statistically likely event of 10 years.

Source: (Maes et al., 2022[37]).

 Coastal flooding

Low-lying coastal communities face a range of coastal flooding hazards, such as storm surges and erosion. These hazards are expected to increase as climate change increases the frequency and severity of coastal floods. The most exposed countries are the Netherlands, Belgium and Denmark: approximately 51% of the Netherlands land area is potentially exposed to coastal flooding with a ten-year return period, followed by 6.3% for Belgium and 5.6% for Denmark. These figures should, however, be interpreted with caution as they do not account for existing flood protection measures. Nevertheless, they underscore the importance of maintaining existing protections to prevent future exposures.

With respect to the exposure of built-up areas, of the IPAC countries, the Netherlands has 48.1% of its built-up area exposed to coastal flooding, followed by Belgium (7.1%) and China (4.3%). This reflects the fact that much of the land along the North Sea coast is either below sea level or just slightly above it, exposing a sizeable amount of the land and its built-up areas to coastal flooding hazards.

 Compound effects

Although there are differences across countries, most experience one or more climate-related hazards with varying degrees of intensity. Moreover, countries are not only vulnerable if they are exposed to a specific hazard, but also how these hazards may be interconnected, reinforcing or undermining one another. Future analysis could investigate the interconnectedness between climate-related hazards to develop a composite indicator that identifies which climate-related hazards are more, or less, impactful for a given country.

Climate-related hazards may be reinforced by others and could exacerbate socio-economic impacts, or alternatively be undermined by adaptation policies. The effects of climate hazards are reflected in how countries are affected by losses and damages associated with climate related events. This assessment is essential for adaptation policies and emergency preparedness.