Exposure, Vulnerability, and Adaptation to Climate Hazards

Climate change affects natural and human systems as temperatures rise, rainfall patterns shift, and extreme weather events—such as heatwaves, floods, droughts, and storms—become more frequent and intense.[reference: IPCC2023] These changes disrupt ecosystems and economies alike. Prolonged droughts reduce agricultural yields,[reference: FAO1] floods destroy homes and infrastructure, and heat stress threatens health and productivity.[reference: ILO1]

These impacts are not felt equally. People in different locations face different levels of exposure to climate hazards. But even when faced with the same hazard, some people are more likely to be adversely affected or unable to cope with its impacts— for example, if they live in poverty or lack access to social protection.[reference: WB3]

Let’s see which climate hazards the world’s population is exposed to and what makes people vulnerable.

Not all places are equally exposed to climate-related hazards, and the number of people living in affected areas differs substantially. So, to estimate the number of exposed people per country, we need to overlay the geographical location of the hazards with the number of people living there.

Around 4.5 billion people were exposed to certain climate-related hazards in 2024.[reference: WB1] Exposed population means the people living in an area affected by a given climate-related hazard. An area is considered exposed if the probability that a hazard strikes in a given year is more than 1 percent. This translates into a[emphasis: ]probability of slightly over 50 percent[footnote: To estimate exposure, we consider a 100-year return period, which is the same as a 1 percent probability that the hazard occurs in a given year. Average global life expectancy is 72 years. An event with a probability of annual occurrence of 0.01 has a probability of 1-(1-0.01)^72=0.515 or 52 percent of occurring in a 72-year period. ] that a person faces the hazard over their lifespan. Weather events are considered hazards when their intensity is high enough to significantly impact lives, assets, and livelihoods.[footnote: We use hazard-specific thresholds to determine whether a climate-related hazard has a significant impact. For instance, for floods, we use a threshold for inundation depth, and for cyclones, a threshold for wind speed.]

While there are many climate-related hazards, we focus on [emphasis: floods],[emphasis: ][emphasis: agricultural droughts], [emphasis: cyclones][emphasis: ]and [emphasis: heatwaves]. Let’s explore the number of people exposed to each of these climate-related hazards.

[emphasis: Floods] occur because of heavy rain, overflowing rivers, and rising sea levels. Climate change affects precipitation patterns, snow and ice melt, and sea level rise, leading to more frequent and heavier floods.[reference: UNEP1]

[emphasis: Agricultural droughts] occur when there is not enough soil moisture and water availability to meet the needs of crops and livestock, reducing agricultural production and undermining both food security and rural livelihoods. Climate change is intensifying such droughts by increasing their frequency, severity, and duration, placing growing pressure on already vulnerable farming systems.

[emphasis: ]

[emphasis: Cyclones], also known as hurricanes or typhoons, are large revolving storms that form over tropical oceans.[footnote: These are known by different names, depending on their location. Over the Atlantic and East Pacific Oceans, they are commonly called hurricanes; in the West Pacific Ocean, they are referred to as typhoons; and in the Indian Ocean and around Australia, they are called cyclones.] Climate change causes ocean water temperatures to rise, increasing the strength of cyclones and resulting in heavier rainfall.

[emphasis: Heatwaves] are prolonged periods of unusually high temperatures. Heatwaves can impact human health through an increase in the risk of dehydration, heat exhaustion and heatstroke, and worsen cardiovascular and respiratory diseases. This significantly raises mortality, especially among older adults and people with pre-existing conditions.[reference: WHO1] Heatwaves can also reduce economic output, as labor productivity becomes more strenuous, particularly in outdoor activities such as agriculture, construction, and manufacturing. They also increase demand for electricity, and put additional stress on infrastructure and health care systems.[reference: ILO1]

If we overlay exposures to [emphasis: floods],[emphasis: ][emphasis: agricultural droughts], [emphasis: cyclones][emphasis: ]or [emphasis: heatwaves] with population density, 4.5 billion people—or around 57 percent of the world’s population—is exposed to at least one climate hazard. No country has no people exposed to one of the four hazards, but the share of people exposed varies from <1–100 percent of a country’s population.

Mapping climate-related hazards is only half the task; the other half is understanding people’s vulnerability to such climate hazards. The loss of income or damage to property caused by a [emphasis: cyclone], [emphasis: heatwave], [emphasis: drought], or [emphasis: flood ]may be a small inconvenience for some, but a long‑term livelihood shock for others. The impact depends on people’s ability and capacity to cope, adapt, and recover. In other words, climate risk is shaped not just by exposure, but also by vulnerability.

The World Bank has identified seven dimensions to assess a person’s general level of vulnerability, grouped into physical and economic vulnerability: physical vulnerability is measured by people’s access to [emphasis: clean water],[emphasis: electricity],[emphasis: services and markets];[emphasis: ]economic vulnerability is measured by [emphasis: income],[footnote: See also the chapter on extreme poverty.] [emphasis: education level], and access to [emphasis: social protection ]and financial services ([emphasis: financial inclusion]).[reference: WB2] Individuals are considered to live in highly vulnerable conditions if they score below specific thresholds on at least one of these seven dimensions—for example, if their income falls below the extreme poverty line of $3 a day.[reference: WB2]

More than 1-in-3 people globally are considered highly vulnerable in at least one dimension, and many experience vulnerability across several dimensions. Let’s look at how many people are in vulnerable conditions in each country and which dimensions of vulnerability they are experiencing.[footnote: In this graphic, we restrict ourselves to the six dimensions of vulnerability that come from household surveys. The seventh dimension is [emphasis: access to services and markets], which is measured using spatial data. As it is not possible to combine the spatial data with the survey data, we could not assess the overlap of this dimension with the six others. But spatial vulnerability affects only 44 million of the world’s 2.8 billion vulnerable people.]

When we combine exposure to climate-related hazards with vulnerabilities, we can identify people who are [emphasis: at high risk from climate-related hazards]. People are considered at high risk when they are exposed to any of the four climate-related hazards and are considered highly vulnerable.

Almost 20 percent of the global population is at high risk from climate-related hazards. Across countries, the population at high risk can differ widely due to differences in either exposure or vulnerability.

Climate-related hazards can threaten people’s health, livelihoods, food security, and safety, deepening existing inequalities. People at high risk are those who are exposed to climate-related hazards—such as floods, agricultural droughts, cyclones and heatwaves—and also live in vulnerable conditions. In 2024, 4.5 billion people were exposed to climate-related hazards and 2.8 billion lived in highly vulnerable conditions. Looking at the overlap between these two groups, 1.5 billion people were at high risk from climate-related hazards.

To reduce the number of people at high risk, governments need to pursue both climate mitigation and adaptation. Taking measures to reduce greenhouse gas emissions and limit future warming can help slow the growth of climate-related hazards and exposure to them. Governments are also working to reduce people’s vulnerabilities and increase their resilience towards climate-related hazards. The World Bank’s [emphasis: Adaptation and Resilience Readiness Assessment Tool] assesses how well countries are positioned to design and implement effective climate change adaptation and resilience strategies by evaluating key policies, institutions, and actions across multiple pillars and indicators.[reference: WB1]

This tool, first applied in 17 Caribbean economies, has guided adaptation efforts elsewhere, too. For example, World Bank–supported programs have helped [emphasis: Zambia ]and [emphasis: Brazil ]shift from reactive to proactive resilience building, contributing to substantial declines in vulnerability and the number of people at high risk from climate-related hazards. Experiences like these show that reducing climate risk is possible, even as exposure increases. Continued investments in adaptation, resilience, and inclusive development can further reduce vulnerabilities and protect lives and livelihoods from shocks, including climate‑related shocks.