The Climate Action Monitor 2024

2. How are climate-related hazards and disasters affecting the world?

In 2024, the world once again witnessed the dramatic consequences of climate change – from record-high temperatures, storms and unprecedented rainfall to droughts, wildfires, and other intense and unexpected climate-related hazards. These impacts continue to pose serious threats to ecosystems and communities worldwide.

Extreme weather events are becoming the norm, leading to significant damages and loss of life. These effects can manifest as slow onset events (such as gradual sea-level rise) or sudden extreme events (such as flash floods or intense storms) (IPCC, 2022[1]). Between 2021 and 2023, annual economic losses due to climate-related disasters were estimated at USD 250-280 billion (Munich RE, 2024[2]; 2023[3]; 2022[4]),1 while around 24 000 lives were lost globally as a result of these disasters (CRED, 2024[5]).

The dramatic extreme weather events changes observed in 2024 are isolated events but consistent with long-term trends that can only be understood by tracking hazards and disasters over decades. Drawing on global Earth Observation and other geospatial data sources, the International Programme for Action on Climate (IPAC) has developed indicators for a variety of climate-related hazards. The indicators focus on seven key climate hazards and four exposure domains, providing a time series that goes back as far as 44 years for all countries globally (Maes et al., 2022[6]).

This chapter explores the impacts and risks of climate change using historical observation data and introduces some key underlying data on future climate-related hazards. It shows how climate-related hazard exposures can vary across and within countries due to diverse geography, environment and weather patterns that affect each area in both OECD and OECD partner countries.

The indicators follow national and international guidelines and are based on the conceptualisation of climate risk of the Intergovernmental Panel on Climate Change (IPCC). These consider climate-related hazard, exposure and vulnerability as the key dimensions of disaster risk (IPCC, 2022[1]). The indicators have recently been updated and some key results are discussed below.

IPAC aims to further enhance this indicator set through forward-looking indicators for three key climate hazards and two exposure domains to 2100 (Box 2.1). Assessing future exposure of climate-related hazards is increasingly important. If the world continues on its emissions trajectory and does not meet the Paris Agreement temperature goals, estimates suggest that global gross domestic product (GDP) could fall by 7-10% by 2050 (Swiss Re, 2021[7]). If no action is taken, and temperatures continue to rise to 3.2°C by 2050, global GDP could drop even further – by 18% (Swiss Re, 2021[7]).

Box 2.1. Assessing future impacts and risks of climate-related hazards using IPCC Shared Socioeconomic Pathways

The Intergovernmental Panel on Climate Change (IPCC) uses and synthesises the scientific findings from climate models worldwide for its Assessment Reports. In work under development, IPAC uses the same projections from the latest generation of climate models that participated in the sixth phase of the Coupled Model Intercomparison Project (CMIP). The CMIP initiative serves as an experimental framework that harmonises climate modelling efforts across different research institutions worldwide. By using a multi-model perspective, it enables a more nuanced and reliable view of climate projections and captures the uncertainty inherent to climate models (Tebaldi and Knutti, 2007[8]).

Ongoing IPAC work uses CMIP6 Shared Socioeconomic Pathways (SSPs) that quantify and define the socio-economic circumstances - such as population growth, economic activity, energy intensity and land-use change - under which emissions, atmospheric concentrations and resulting radiative forcings can (or cannot) be changed (Riahi et al., 2017[9]).

Four climate scenarios are proposed (Figure 2.1Figure 2.1. Climate scenarios cover a broad range of CO2 emissions and economic development pathways). SSP1-1.9, the most optimistic scenario, represents a climate response to the Paris Agreement temperature goal to limit global average temperature rise to 1.5 °C by 2100. SSP1-2.6 also builds on sustainable development with substantial emissions cuts, but net-zero emissions are only reached after 2050.

SSP2-4.5 is a “middle-of-the-road” scenario. It offers differing levels of economic growth and sustainable development among countries that prevent reaching net-zero emissions by 2100. SSP3-7.0 presents a pathway where strong competition among countries and concerns over energy and food security hamper both mitigation and economic growth, causing emissions to roughly double by 2100.

Figure 2.1. Climate scenarios cover a broad range of CO2 emissions and economic development pathways

Global CO₂ emissions for CMIP6 climate scenarios

Note: This figure uses three Tier-1 SSP scenarios SSP1-2.6, SSP2-4.5 and SSP3-7.0 and one Tier-2 SSP scenario SSP1-1.9, while excluding SSP5-8.5 that is considered worse than the business-as-usual scenario.

Source: Data obtained from (Riahi et al., 2017[9]), (Rogelj et al., 2018[10]) and (Gidden et al., 2019[11]).

Rising extreme temperatures are affecting billions of people worldwide

Dangerous temperature levels are increasingly common around the world. IPAC data reveal a significant rise in the number of days with above-average temperatures across all countries (Figure 2.2. On average OECD and OECD partner countries experience an additional 30 days with above-average temperatures). On average, there were an additional 30 days per year with above-average temperatures across OECD and OECD partner countries in 2019-23 compared to 1981-2010. This corroborates recent findings that Earth experienced its warmest day in recent history with global average temperatures peaking at 17.16°C on 22 July 2024 (C3S, 2024[12]).

Changes to extreme heat events involve determining a relative or absolute threshold beyond which conditions are considered extreme. In this analysis, which follows IPCC AR6 (IPCC, 2021[13])2, a hot day exceeds 35°C (Maes et al., 2022[6]), while a tropical night does not go below 20°C. OECD indicators highlight that more and more people are increasingly exposed to extreme heat events. Since 1979, the population in all IPAC countries, both OECD and partner countries, has been increasingly exposed to hot days.3 An estimated 12% more people in OECD and partner countries were exposed to such conditions in 2019-23 compared to the reference period 1981-2010 (Figure 2.3).

Countries whose population was most exposed to hot days (more than 2 weeks) in 2019-23 comprise Saudi Arabia (96.5%), India (89.3%), Spain (35.4%) and Israel (32.4%), an estimated 1.5 billion people in total. Although historical exposure to extreme temperatures in countries such as Saudi Arabia and Israel was already notably high, exposure is lasting longer.

Reports on the ground corroborate OECD indicators, indicating 15 broken national heat records and an additional 130 monthly national temperature records shattered in the first half of 2024 (The Guardian, 2024[14]). For example, New Delhi experienced more than 40 days with temperatures above 40°C between May and June 2024, with one part of Delhi reaching 49.9°C. To make matters worse, hotter nights deprive people of the time needed to recover from the extreme heat experienced during the day. A report from the Centre for Science and Environment Analysis illustrates how heightened humidity and the urban heat island, driven by climate change, exacerbate heat stress conditions in Delhi (CSE, 2024[15]). Moreover, extreme heat is experienced differently across groups who do not have resources to protect themselves. Low-income people and environment systems are especially vulnerable to extreme heat (Page, 2024[16]).4

Climate scenarios also project that extreme heat will increasingly affect parts of Central and South America. Under a high-emissions scenario,5 large parts of Central and South America are projected to face an escalating exposure to hot days by 2100, including countries such as Brazil, Colombia, El Salvador and Venezuela (Figure 2.4). This indicates that extreme heat exposure is likely to intensify, even in tropical areas that traditionally encounter high levels of extreme heat during certain times of the year.

Figure 2.4. By 2100, extreme heat is projected to intensify in parts of Central and South America

Additional yearly number of hot days under a high-emissions scenario, Central and South America, 2080-2099, compared to the reference period 1995-2014.

Note: More information on a high-emissions scenario can be found in Box 2.1. No robust change is illustrated as dashed area.

Robust change of values in a multi-model ensemble are defined as where ≥ 66% of climate models show a significant change (i.e. change greater than the variability threshold) and where ≥ 80% of all climate models agree on the sign of change (IPCC, 2021[13]).

Source: OECD visualisation using data from (Climate Change Knowledge Portal, 2024[17]).

Tropical nights, associated with high night-time temperatures, generate risks to human health due to sleep disturbances and inability to cool down at night (Seltenrich, 2023[18]), as well as increased economic costs. In the 44 years between 1979-83 and 2019-23, OECD and partner countries experienced an estimated increase in nine additional tropical nights. Of the 50 countries and the EU covered, 21 had more than an additional 10% of their population exposed to tropical nights6 over 2019-23 compared to 1981‑2010. Meanwhile, countries such as Korea (28.9%), Italy (19.6%) and Greece (17%) had the highest increase in population exposed to more than 8 weeks of tropical nights7 (Figure 2.5).

In line with the increasing average temperature trend, the exposure to extreme cold is decreasing. The share of global population exposed to icing days is decreasing year by year. An estimated 6.9% fewer people faced such conditions during 2019-23 compared to 1981-2010.

Worsening droughts threaten food supplies

Rising temperatures have adverse effects on food systems, with croplands increasingly more vulnerable to agricultural droughts. Across the OECD and OECD partner countries, there was a significant decrease in soil moisture levels on croplands (2.9%) during 2019-23 compared to the reference period 1981-2010. The countries most affected by agricultural droughts include Argentina, Brazil, Mexico, and Romania, that witnessed average declines exceeding 6% in cropland soil moisture over the past five years (Figure 2.6). In fact, Argentina, Brazil and Mexico recorded their highest decline in cropland soil moisture in 2023 since the starting period of this indicator (1981).

National averages hide large differences and changes at the subnational level, where recorded drops in soil moisture are greater (Figure 2.7). In Europe, for example, OECD data show that South East, North East and South Muntenia in Romania have experienced severe soil moisture declines of 9.2%, 8.5% and 7.2%, respectively (Figure 2.7). Similarly, the Bulgarian regions of North East, North Central and South East experienced soil moisture declines of 8%, 7.6% and 5.4%, respectively.

These findings are concerning, especially since these regions have more than 50% cropland cover, and since agriculture plays an important socio-economic role in people’s lives and livelihoods. Most of Romania’s poor live in rural areas, for example, and depend on agriculture-related activities for their livelihoods (World Bank, 2018[19]). As 2024 unfolded, Romanian farmers faced another difficult year due to lack of rain.

Worsening drought conditions in these regions underscore a grim reality: climate change is intensifying the frequency and severity of such impacts. With each passing year, the effects of climate change are becoming more pronounced. Already, fragile agricultural sectors in regions of Romania, Bulgaria and elsewhere are increasingly at risk. Dwindling soil moisture makes it harder to sustain crops and, by extension, livelihoods. Substantial efforts are needed to address the root causes of climate change and build resilience in these vulnerable areas.

Figure 2.7. Regions in southern and eastern Europe are experiencing the most severe drought impacts in Europe

Land soil moisture anomaly (%), 2019-23 average compared to the reference period 1981-2010 across Europe

Note: <Negative values indicate increasing drought conditions in the topsoil layer, while positive values indicate wetter conditions in the topsoil layer compared to the reference period 1981-2010.

Source: (Maes et al., 2022[6]).

Record wildfires were experienced in 2023

Wildfires have continued to devastate regions around the world in 2024. This is consistent with global trends and OECD data highlighting that 24.5% of globally burned area between 2019 and 2023 was located in OECD and OECD partner countries. In countries such as Argentina, Australia, Brazil, Colombia, India and South Africa, more than 1% of land area burned each year during this period. This represented more than 660 000 km² – roughly equivalent to the size of France. Burning land, whether from wildfires, controlled burning or uncontrolled biomass fires, has far-reaching consequences that hinder efforts to combat climate change and undermine initiatives aimed at mitigating global warming.

In the southern hemisphere, the Brazilian Amazon has experienced its worst six months of wildfires in over 20 years due to historic drought, with 13 489 wildfires recorded (Genot, 2024[20]). Similarly, a record number of fires occurred in the state of São Paulo in August, primarily caused by human activities according to the National Secretary of Protection and Civil Defence (Salati, 2024[21]). It reported significant financial losses, an estimated USD 179 million (R$ 1 billion) for rural producers in the region (Salati, 2024[21]).

In the northern hemisphere, Canada experienced a record-breaking number of wildfires in 2023, with more than 150 000 km² of land burned by the end of August. Some fires even continued to smoulder over winter and re-ignited as early as February. Larger wildfires were recorded in Alberta, British Columbia and Manitoba as early as May 2024 (Faguy, 2024[22]). The 2024 wildfire season is now set to have the second-highest carbon emissions on record, following last year’s destructive season (CAMS, 2024[23]). Many more wildfires were recorded in Chile, Colombia, Greece, New Zealand, Portugal, Türkiye and the United States.

Wildfires are becoming more widespread, increasing ecosystem damage, notably biodiversity and carbon sinks, and harm to human life. Between 2018 and 2022, about 3.2% of the population in IPAC countries, covering both OECD and OECD partner countries lived in areas with very high or extreme wildfire danger, representing over 160 million people. Countries with the highest population exposure to very high and extreme wildfire danger include South Africa (41.2%), Australia (19%), Costa Rica (12.4%), Brazil (9%) and Chile (8.7%), exposing a combined population of more than 51 million people. In absolute terms, India's population faces the highest overall exposure to wildfires during this period: more than 38 million people live in areas with very high and extreme wildfire danger.

Overall, forests in OECD and partner countries have been more exposed to very high or extreme wildfire danger. For example, in the last five years, Brazil has faced the largest area of forest exposed (~1.9 million km²) to wildfire danger. Other countries, such as the United States, Australia and Mexico, also have elevated levels of wildfire, with 516 000 km², 622 000 km² and 614 000 km², respectively, exposed to very high or extreme fire risk. Within OECD countries, Israel, Mexico and Portugal have some of the highest percentages, with more than 74% of forest exposed to wildfire danger between 2018 and 2022 (OECD, 2023[24]). These large areas of exposure highlight the considerable risk to forests. Consequently, they should be a policy priority given both human risk and the key role forests play as carbon sinks globally.

Extreme rainfall events continue to cause havoc, resulting in devastating floods and landslides

Heavy rainfall poses significant dangers to countries by causing flash floods, triggering landslides, and potentially affecting both people and economic infrastructure. OECD and partner countries are increasingly exposed to extreme precipitation events for longer periods, with OECD partner countries having a much higher share of land exposed compared to OECD countries (Figure 2.9).

Although most countries monitored by IPAC are exposed to some level of extreme precipitation events, the duration of exposure varies considerably between countries. The OECD and partner countries with the highest share of land exposed to extreme precipitation events between 2019 and 2023 included Indonesia (37.3%), Colombia (28.2%), Peru (22.4%) and Brazil (15.8%).8 These countries experience higher precipitation due to their location in the tropical region with its warmer temperatures and abundant moisture, among other factors.

Between April and May 2024, large regions in central Asia experienced heavy rainfalls and subsequent flash flooding (Zachariah et al., 2024[25]). This extreme rainfall event was highly unusual, occurring in a so-called hyper-arid region. It was likely worsened due to a combination of human-induced climate change and the El Niño Southern Oscillation in 2023-24 (Zachariah et al., 2024[26]). However, it is difficult to attribute human-induced climate change to specific hazard and disaster events such as this one.

In India, an extreme monsoon rainfall killed hundreds of people due to massive landslides, with the mountainous western Ghats district the worst affected (Zachariah et al., 2024[27]). Across northern Kerala, bridges were washed away, homes and roads were flooded, and power outages occurred. With over 140 mm of rain falling in a single day on already saturated soils, deadly landslides followed (Zachariah et al., 2024[27]). While extreme rainfall events often have localised or regional impacts, they may also have broader national consequences due to the loss of life and economic damage.

In Europe, land exposure to extreme precipitation events remains low (< 2%). However, the wetter-than-average spring of 2024 offered the opportunity to replenish groundwater levels and replenish aquifers over much of western Europe. Record seasonal precipitation was recorded in parts of France, Italy, the Netherlands, Belgium and Ireland (C3S, 2024[28]).

Although dependent on crop types, extreme precipitation events can pose dangers to agriculture by causing flooding, eroding and/or saturating soils, damaging crops, and threatening food production and livelihoods. This can be especially problematic for countries dependent on agriculture. It can make them overly vulnerable to precipitation changes due to climate change.

On average, Indonesia (32.7%), Colombia (12.3%), Peru (10%), Costa Rica (9.8%) and Brazil (3.3%) had the highest share of cropland exposed to extreme precipitation events over 2019-23. The share of cropland exposed to extreme precipitation events has increased for several countries. In Indonesia, for example, such events increased from about 3.4% to 25.2% between 2000-23.

Six of ten countries whose cropland area is most exposed to extreme precipitation events also depend more on agriculture as a share of GDP. For example, Indonesia and Colombia have, on average, about 33% and 12% of cropland, respectively, exposed to extreme precipitation events. Meanwhile, their GDP share of the agriculture, forestry and fishing sector is 12.7% and 6.4%, respectively, which is significantly higher than the average in OECD and OECD partner countries (3.2%).

Flooding is caused by a combination of factors, including extreme precipitation, storm surges, river overflow and more artificial surfaces, and threatens people’s lives, livelihoods and economic infrastructure. Among the 51 OECD and OECD partners covered by IPAC, the Netherlands and Hungary have the highest percentage (~20%) of total land area exposed to extreme river flooding. Meanwhile, China is the most exposed country with 22% of its built-up area exposed. China is followed by Latvia (20%) and the Netherlands (18%). In terms of agricultural land, the most affected are Hungary, the Netherlands, and the Slovak Republic with more than 17% of their cropland exposed to possible extreme events.9

River flooding can also cause human losses. However, because extreme rainfall and subsequent flooding often have highly localised impacts on populations and infrastructure, many national and subnational indicators may fail to detect these events. In 2023, Europe experienced severe flooding, affecting 1.6 million people across the continent. For example, floods in Italy displaced an estimated 36 000 people and led to 15 fatalities in May. Meanwhile, two-thirds of Slovenia was inundated in August 2023, resulting in six fatalities. Furthermore, record rainfall in Greece, Bulgaria and Türkiye in September 2023, led to 29 deaths and extensive damage, including 700 km² of flooded land in Greece (C3S and WMO, 2023[29]). Among the countries monitored, populations in Latvia, the Slovak Republic and the Netherlands are the most exposed, with more than 30% of people potentially affected. Due to the sheer size of China (26%) and India (20%), the total number of people exposed in these two countries to river flooding is about 670 million (Figure 2.10).

Low-lying coastal communities face a range of coastal flooding hazards such as storm surges and erosion. These hazards are expected to worsen as climate change increases the frequency and severity of coastal floods. The most exposed countries are the Netherlands, Belgium and Denmark. In the Netherlands, 51% of land area is potentially exposed to coastal flooding with a ten-year return period, followed by 6.4% for Belgium and 5.6% for Denmark. However, these figures should be interpreted with caution as they do not consider existing flood protection measures or sea-level rise. Nevertheless, they underscore the importance of maintaining protections to prevent future impacts and the potential economic costs of damage caused by climate change.

Built-up area exposure to coastal flooding is increasing. Across the countries covered by IPAC, the percentage of built-up area exposed to coastal flooding increased from 1.8% in 2000 to 2.6% in 2020.This suggests that additional investment in infrastructure will be necessary, particularly if built‑up areas continue to expand in coastal zones. The most affected is the Netherlands that has 52% of its built‑up area exposed to coastal flooding, followed by Belgium (10%) and China (6.6%). Much of the land along the North Sea coast is either below sea level or just slightly above it. This exposes a sizeable amount of the land and its built‑up areas to coastal flooding hazards.

The hurricane season of 2024 will likely break records due to climate change and La Niña

Storms and cyclones affect all countries covered by IPAC with varying degrees of intensity and occurrence, and at times worsen the effects of other hazards. According to the National Oceanic and Atmospheric Administration, the 2024 hurricane season (1 June to 30 November) will be exceptionally active due to a combination of warmer ocean temperature and a La Niña climate pattern (Jones, 2024[30]). Hurricane Beryl became the earliest forming a Category 5 Atlantic hurricane in recorded history, and the second such storm in July (WMO, 2024[31]). This highlights how warmer ocean temperatures due to climate change risks facilitating cyclogenesis (Knutson et al., 2021[32]).

Countries most exposed to violent storms are located principally in northwest Europe and East Asia. In countries such as Belgium, Iceland, Ireland and the Netherlands, more than 40% of the population and built-up areas were exposed to violent storms in 2019-23 (Figure 2.12). Meanwhile, exposure to tropical cyclones is limited to a subset of countries covered by IPAC due to their geographic position. The most exposed of these countries are Japan and Korea (90%) where more than 90% of their populations and built-up areas are exposed to tropical cyclones (with wind speeds higher than 119 km/h or 33 m/s). These two countries are followed by Mexico and China with 25%.

Economic losses and deaths due to climate disasters

Extreme weather events exacerbate social, political and economic stressors, such as food insecurity. The trajectory of future changes in climate remains uncertain. However, increasing severity of extreme weather events, along with increasing population density in hazard-prone locations, is likely to lead to rising climate-related catastrophic losses (OECD, 2021[33]).

Annual economic losses due to climate-related disasters change from year to year. However, economic losses have tended to increase across IPAC countries since the 1990s (Figure 2.13). Similarly, economic losses due to weather, climate and water extremes have reportedly increased sevenfold from the 1970s to the 2010s (WMO, 2021[34]). Storms are responsible for the largest economic damages (more than USD 2.3 trillion between 1990 and 2023), followed by damages from floods, droughts, wildfires and extreme temperatures (Figure 2.13). Hurricane Harvey in 2017 and Hurricane Ian in 2022 caused estimated economic losses of more than USD 118 billion and USD 104 billion, respectively, in the United States, making them some of the costliest storms on record.

Loss of life due to climate-related disasters is spread differently than economic losses. Extreme temperatures cause a vast majority of deaths related to climate-related disasters. In 2022, for example, a heatwave event in Italy and Spain caused more than 29 000 deaths (Figure 2.14). This illustrates that climate-related disasters with high economic losses are not necessarily the same ones with the highest loss of life.

Developing countries, including Least Developed Countries and Small Island Developing States, are disproportionately affected by the impacts of extreme weather events. This is due to their lower levels of development and economic diversification, fiscal constraints and physical characteristics, among other reasons (OECD, 2021[33]). Due to limited spatial coverage of disasters databases and the under reporting of damages and lives lost, many of these countries have a significant reporting gap (Moriyama, Sasaki and Ono, 2018[35]). The African continent, for example, saw 35% of deaths related to weather, climate and water extremes but just 1% of reported global economic losses (WMO, 2021[36]). These disparities highlight the urgent need for improved data collection and reporting mechanisms to accurately assess the impact of extreme weather events in developing countries and to inform effective climate adaptation strategies.

Evidence in many countries monitored by IPAC confirms that accelerated action on adaptation is needed to contain future loss and damage. Investments in climate adaptation measures are usually significantly less expensive than addressing loss and damage from extreme weather events. For example, one study shows that investing USD 1.8 trillion globally in five areas from 2020 to 2030 could generate USD 7.1 trillion in total net benefits (GCA, 2019[37]). However, government funding is usually only made available after a disaster. This gives rise to important considerations for adaptation finance (OECD, 2023[38]).

Box 2.2. Fund for responding to loss and damage

The 28th session of the Conference of the Parties (COP28), held in Dubai in November and December 2023, led to the formal establishment and operationalisation of the Fund for responding to Loss and Damage. This Fund is set to provide assistance to those countries most vulnerable to, and affected by, the effects of climate change.

Several countries have pledged money to the Fund, including the United Arab Emirates, France, Germany, the United Kingdom and the United States, among others. At its first Board Meeting in April 2024, the Board decided the Philippines would be the host country of the Fund.

To kick start the new funding arrangements, a transitional committee was convened to prepare recommendations for adoption at COP28 in November 2023. It considered the following elements:

• establishing institutional arrangements, modalities, structure, governance and terms of reference for the Fund

• defining the elements of the new funding arrangements

• identifying and expanding sources of funding

• ensuring co-ordination and complementarity with existing funding arrangements.

The Loss and Damage Fund should fill gaps left by current climate finance institutions such as the Green Climate Fund and Adaptation Fund. Campaigners argue that the Loss and Damage Fund must be accountable to the most vulnerable, drawing on the experience of community-based organisations, and favouring grants rather than loans. Financing instruments that could be used to provide a buffer and rapid pay-outs after disasters include social protection, contingency finance, catastrophe risk insurance and catastrophe bonds. However, a broadened donor base and innovative finance tools would be needed to respond to the magnitude of loss and damage.

Source: (UNFCCC, 2023[39]).

Strong climate mitigation efforts are needed to avoid triggering climate tipping points that risk fundamentally changing regional and global climate

The pace of climate change increases the intensity and occurrence of extreme weather events. Climate change risks also further accelerating climate tipping points that disrupt stable climate patterns and amplify climate disturbances on a continental and global scale. Climate tipping points are reached when a change in part of the climate system goes beyond a certain threshold that results in an abrupt and potentially irreversible impact (OECD, 2022[40]).

The risks of climate tipping points, the disintegration of the Greenland Ice sheet, the melting of the Arctic Permafrost or the weakening of ocean circulations cannot be overstated. Evidence shows that under current pledges the world is heading towards 2-3°C of global warming and will likely trigger multiple climate tipping points (Figure 2.15). Climate tipping points interact with each other and can influence the likelihood of triggering another tipping point, creating an unstoppable climate tipping cascade. Allowing for a climate tipping cascade to occur puts the planet in a “state of planetary emergency” (Lenton et al., 2019[41]). Limiting global warming to 1.5°C is crucial to avoid the possibility of accelerating more catastrophic impacts of combined climate tipping points (OECD, 2022[40]).

Figure 2.15. Current global warming may already trigger certain climate tipping points, and become increasingly likely with further warming

Location of climate tipping elements in the cryosphere (blue), biosphere (green) and ocean/atmosphere (orange), and global warming levels at which these tipping points will likely be triggered.

Source: Illustration from (Armstrong McKay et al., 2022[42]).

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Notes

← 1.  Including non-climate related disasters such as earthquakes.

← 2.  Absolute thresholds used to determine hot days can vary from 30 °C to 50 °C, depending on their use. More complex indicators, such as the Universal Thermal Climate Index, can describe extreme heat, combining other factors such as moisture, wind and solar radiation to account for a more thorough analysis to heat exposure for individual countries.

← 3.  Hot days are defined as those during which daily maximum temperature surpasses 35 °C. Due to the resolution of the raw data, extreme heat for small islands may be slightly under-estimated. There are also several additional indicators to describe extreme heat (such as the Universal Thermal Climate Index, which also considers moisture, wind and solar radiation); these should be considered for a more thorough analysis of exposure to heat for single countries.

← 4.  For example, in June 2024, more than 1 300 Muslims died during the annual pilgrimage to Mecca, as temperatures soared above 50 °C. Reportedly, 83% of these fatalities involved unregistered pilgrims, who sought to avoid high pilgrimage costs. In the case of wildlife a strong high pressure system in May 2024 over the southern Gulf of Mexico caused a heat dome, where howler monkeys and other wildlife died due to dehydration (Euronews Green, 2024[43]).

← 5.  By using a multi-model perspective consisting of up to 30 climate models, reliable climate projections that capture uncertainty provide insights on future changes of key hazards such as hot days.

← 6.  Tropical nights are defined as nights where the minimum temperature does not fall below 20 °C. Due to the resolution of the raw data, extreme heat exposure for small islands may be slightly over- or under-estimated. There are also several additional indicators to describe extreme heat (such as the UTCI), which also takes moisture, wind and solar radiation into account); these should be considered for a more thorough analysis of exposure to heat for single countries.

← 7.  Annual population exposure to more than eight weeks of tropical nights.

← 8.  Extreme precipitation is defined here as precipitation of more than one week.

← 9.  River flooding events are defined in terms of a 100-year flooding event.