Climate change risk assessment 2021

The risks are compounding, and without immediate action the impacts will be devastating.

Research paper Updated 4 November 2021 ISBN: 978 1 78413 491 4

Photo shows rescue workers in boats working to evacuate a flooded hospital in Zhengzhou, China

Dr Daniel Quiggin

Senior Research Fellow, Environment and Society Centre

Dr Kris De Meyer

Research Fellow, Department of Neuroimaging, King's College London

Dr Lucy Hubble-Rose

Honorary Research Fellow, Climate Action Unit, University College London

Antony Froggatt

Former Senior Research Fellow and Deputy Director, Environment and Society Centre

At COP26, the governments of highly emitting countries will have a critical opportunity to accelerate emissions reductions through ambitious revisions of their nationally determined contributions (NDCs).

If emissions follow the trajectory set by current NDCs, there is a less than five per cent chance of keeping temperatures well below 2°C above pre-industrial levels, and less than one per cent chance of reaching the 1.5°C target set by the 2015 Paris Agreement.

Unless NDCs are dramatically increased, and policy and delivery mechanisms are revised accordingly, many of the climate change impacts described in this research paper are likely to be locked in by 2040, and become so severe they go beyond the limits of what nations can adapt to.

As well as the immediate physical and socio-economic consequences of changes in climate, the paper captures the systemic cascading risks likely to arise as these direct risks and impacts compound to affect whole systems, including people, infrastructure, the economy, societal systems and ecosystems.

A summary report of the research findings, intended for heads of government, is also available as a PDF download in English, Arabic, Chinese, French, Japanese, Portuguese and Spanish versions.

03 Direct climate impacts

Unless emissions are dramatically reduced, many of the direct impacts of climate change will likely be locked in by 2040, and could become so severe they go beyond the limits of what many countries can adapt to.

3.1 Approach: how to understand the impacts presented

This chapter presents impact indicators of the most significant global and regional direct risks of climate change, under the RCP4.5 GHG concentration trajectory, which approximately maps to the emissions trajectory identified in Chapter 2. The quantitative analysis of each direct risk and associated impact (Figures 3–18) is entirely sourced from Nigel Arnell and colleagues (2019).8 Whereas they present the major climate hazards as a function of time, with the associated climate impacts illustrated at discrete time horizons (2050 and 2100), in this paper we draw on their decadal data to present – for the first time – these climate risk impacts as function of time.9

The approach of presenting the major climate risk impacts as a function of time partially follows the approach laid out by Simon Sharpe (2019):

The risks of climate change can be understood more clearly when research starts by identifying what it is that we most wish to avoid and then assesses its likelihood as a function of time. By providing a clearer picture of the overall scale of the risks of climate change, such assessments could help inform the most important decision of all: how much effort to put into reducing emissions.10

The difference between Sharpe’s approach and the one used in this paper pertains to the thresholds applied to a given climate impact. Defining ‘what it is that we most wish to avoid’ requires geographically specific thresholds of concern/impact, as societies across different regions do not necessarily have equivalent vulnerabilities to a given climate hazard. For instance, an equivalent temperature in two regions could be defined as a severe heatwave in one while having little impact in another. As such, thresholds of concern/impact need to be defined by stakeholders in each region to enable an assessment of what it is we wish to avoid, and subsequently its likelihood over time. This bottom-up approach to assessing climate risks and impacts requires significant stakeholder engagement across all regions of the world, to then work backwards and identify the climatic conditions that would bring them about.

For this paper, a top-down approach to assessing direct climate impacts is followed, with standardized thresholds applied across all regions. For instance, the threshold for defining a major heatwave requires the temperature of a given region to exceed the 99th percentile of the reference period for four or more consecutive days in one year. As such, the direct risks and associated impacts in this chapter should be treated as indicators of impact. As highlighted by Sharpe (2019), it is integral to define what we wish to avoid in assessing the risks of climate change. The thresholds of impact for each indicator are described in the coming sections, as each impact is presented, but for fuller detail see the work of Arnell and colleagues (2019).11

The risks of climate change can be understood more clearly when research starts by identifying what it is that we most wish to avoid and then assesses its likelihood as a function of time (Sharpe, 2019).

There is a clear need for subsequent research to engage stakeholders in all regions of the globe to define geographically specific thresholds of concern/impact. However, the top-down approach used here does enable impact indicators to be assessed under a common emissions scenario (as described in Chapter 2).

Climate hazards do not translate neatly into impacts. Impacts require exposure and vulnerability to be defined in order to quantify the impact of any given hazard. Shifts in population, innovation, advances in healthcare, and infrastructure will all alter the vulnerability and exposure of societies to a given climate hazard. Exposure is represented by shared socio-economic pathway 2 (SSP2).12 While five SSPs are commonly used,13 SSP2 has been selected on the basis that: (a) it represents a similar trend in decarbonization action that the emissions trajectory indicates; (b) it represents a middle ground along the spectrum of challenges for mitigation and adaptation. Just as with the selection of RCP4.5, using SSP2 to quantify climate impacts does not represent a prediction, but rather a plausible projection. SSP2 is characterized in full by O’Neill and colleagues (2017), but is summarized as:

The world follows a path in which social, economic, and technological trends do not shift markedly from historical patterns. Development and income growth proceeds unevenly, with some countries making relatively good progress while others fall short of expectations … Even though fossil fuel dependency decreases slowly, there is no reluctance to use unconventional fossil resources. Global population growth is moderate and levels off in the second half of the century.14

While direct risk impacts are graphically represented (Figures 3–18) at a given indicator threshold of impact, plotting their likelihood as a function of time, the 2040–50 time horizon is generally used to highlight the impact within the text. This allows readers to make a comparative assessment of risks between geographies and impact types.

The uncertainty associated with the following impacts of direct climate risks (under RCP4.5) set out in this chapter has two principal sources: (1) the change in global mean temperature, which in turn is a function of equilibrium climate sensitivity, ocean diffusivity and carbon cycle feedback; and (2) the spatial pattern of change in temperature and precipitation. The total uncertainty is represented by the shaded areas in Figures 3–18, with the lower and upper bounds of that area indicating the 10th and 90th percentiles of the distribution of impacts in each year. These bounds can be regarded as the low and high estimates of the given impact, with the solid line representing the median, or central, estimate. As discussed in Box 1, the high or upper estimate represents the plausible worst-case scenario (under RCP4.5). However, these do not capture the behaviour of the tails of the probability distribution – e.g. what is the maximum plausible number of days of heatwaves – and so almost certainly under-represent the plausible worst case.

Whereas a wide range of hazards and impacts were assessed by Arnell and colleagues (2019), both at the continental and regional levels, this paper presents the impacts to which the greatest number of people or cropland are exposed. It also takes into consideration impacts with the greatest increases relative to historic baselines, and where the avoidance of climate change significantly reduces a given impact.

Box 2. Tipping points

The study by Arnell and colleagues (2019) is robust, based on current climate science, with 23 CMIP515 climate models used to characterize uncertainty in the regional patterns of climate change. However, there are growing concerns that many climate models may under-represent the influence of tipping points on global mean temperature, which climate science is increasingly indicating could be a key determinant of future temperatures even at low levels of climate forcing.16

Tipping points can be thought of as large discontinuities, or abrupt changes, occurring as a critical earth system threshold is passed. One such instance is the melting of the permafrost in the Arctic leading to the release of methane, which is 30 times more potent than CO₂. Many tipping points additionally have feedback or cascading effects on the rate of climate change. As such, passing the threshold of one tipping point can increase the risk of passing the threshold of triggering another.

Critically, certain thresholds could be reached at lower levels of temperature increase than previously thought. The latest IPCC climate models show a cluster of such abrupt shifts between 1.5°C and 2°C.17 Therefore the risk is that around this level of temperature rise, a cascade of tipping points could be triggered, vastly accelerating climate change and generating catastrophic impacts. Indeed, some initial results from the latest climate models, part of the IPCC’s ongoing Sixth Assessment Report cycle, demonstrate greater climate sensitivity (temperature response to a doubling of atmospheric CO₂) than shown in earlier models.18

Global temperatures can rise significantly beyond those described in the previous chapters. Current atmospheric CO₂ concentration is around 420 parts per million (ppm). Around 3 million years ago, atmospheric CO₂ was between 350 and 450 ppm, and global mean surface temperatures were between 1.9° and 3.6°C higher than the pre-industrial climate. However, global temperatures have been much higher: around 50 million years ago, atmospheric CO₂ exceeded 1,000 ppm, while global mean surface temperatures were 9° to 14°C.19

Ice sheets are crucial for the stability of the climate system as a whole, and are already at risk of transgressing their temperature thresholds within the Paris range of 1.5°–2°C.20 A domino-like effect has recently been identified between various tipping points, which can lead to abrupt non-linear responses. Tipping point cascades (two or more tipping points being initiated for a given temperature level) have been identified in more than 60 per cent of simulations, for which the initial trigger is likely to be polar ice sheet melting, with the Atlantic Meridional Overturning Circulation (AMOC) acting as a mediator transmitting cascades.21

The implications for this risk assessment are clear. If cascading tipping points are indeed reached at lower temperatures, for the same emissions trajectory, most of the impacts presented in chapters 3 and 4 are likely to under-represent the effects on people and cropland, with impacts occurring with a higher probability sooner in time. Furthermore, the severity and frequency of the impacts will be far more extreme, which in turn will greatly reduce the capacity of societies the world over to adapt, compounding the impacts.

Examples of tipping points include:

Greenland and West Antarctic ice sheet disintegration: Melting of ice reduces reflection of sunlight back into space, resulting in accelerated warming and increased sea level rise.
Permafrost loss: Abrupt increase in emissions of CO₂ and methane through the thawing of frozen carbon-rich soils. Methane is a more potent greenhouse gas than CO₂, resulting in accelerated warming.
AMOC breakdown: Shutdown of the AMOC caused by an increased influx of freshwater into the North Atlantic, reducing the ability of oceans to disperse heat around the globe and thus impairing oceans’ ability to provide cooling.
Boreal forest shift: Dieback of boreal forests potentially turning some regions from a carbon sink to a carbon source as pests and wildfires create large-scale disturbances.
Amazon rainforest dieback: Dieback of the rainforest and a shift towards savannah, resulting in large release of CO₂ from that stored within the forests.

3.2 Heat, productivity and health

Increased temperatures and heatwaves are increasingly limiting labour productivity and causing heat-stress-related mortality. In 2019 a potential 302 billion working hours were lost due to temperature increases globally, 52 per cent more than in 2000.22 To put this in context, COVID-19 resulted in around 580 billion lost working hours globally in 2020;23 hence temperature increases are already resulting in the equivalent of more than half of COVID-19-induced lost working hours. India’s agricultural sector accounted for 39 per cent of the heat-related lost working hours in 2019. In southern areas of the US, 15–20 per cent of daylight working hours were lost during the hottest month of 2018.24 Globally, heat-related mortality among people aged over 65 increased by nearly 54 per cent over the period 2000–18, reaching 296,000 deaths in 2018. Of heat-related deaths in the latter year, 62,000 were in China, 31,000 in India, and 104,000 across Europe.25

By the 2030s, more than 400 million people globally each year are likely to be exposed to temperatures exceeding the workability threshold.26 Also by the 2030s, the number of people exposed to heat stress exceeding the survivability threshold27 is likely to surpass 10 million each year.28, 29

Figure 2. Number of people exposed to heat stress above the risks to workability and survivability thresholds at a given change in global mean surface temperature relative to pre-industrial levels

— Source: Adapted from Andrews et al. (2018).

Globally, the central estimate indicates that over 8.2 billion people will experience a heatwave of two or more consecutive days per year by 2050 (Figure 3a), equivalent to 90 per cent of the global population.30 This climate risk impacts a far greater proportion of the global population than any other direct risk assessed.

Protecting citizens from the consequences of heatwaves will be challenging for all governments. More worryingly, some 5.2 billion people – just over half the world’s population – are expected to be subjected to major heatwaves of at least four consecutive days per year under the central estimate; this exposure extends to more than 95 per cent of the global population under the plausible worst-case scenario. Clearly, all things being equal, the larger the population size in 2050, the larger the number of people exposed to heatwaves. However, if climate change were averted completely, fewer than 0.5 billion people would experience major heatwaves, over 90 per cent below the central estimate. By 2040, 3.9 billion people are likely to experience major heatwaves, 12 times more than the historic average. While major heatwaves are defined as being at least twice as long as heatwaves, the temperatures experienced by people are also greater.31

By 2040, 3.9 billion people are likely to experience major heatwaves, 12 times more than the historic average.

As well as considering heatwaves in terms of the number of people experiencing a minimum number of consecutive days of a given severity of temperature, it is important to consider the duration of heatwaves. The central estimate indicates that 135 billion person days per year in 2050 will exceed the 98th percentile of warm season temperatures, within the reference period. Hence, the average person globally in 2050 will experience 14.6 days of heatwaves per year, compared with 1.1 days if climate change were averted.

Figure 3a. Global population experiencing a heatwave that exceeds the 98th percentile of the reference period (1981–2010) for two or more consecutive days per year

Figure 3b. Global population experiencing a major heatwave that exceeds the 99th percentile of the reference period (1981–2010) for four or more consecutive days per year

— Shaded areas represent the lower and upper estimates of the given impact. Solid lines represent the central estimate. Dashed lines represent no additional climate change. Source: Adapted from Arnell et al. (2019).

Regional heatwaves

No region will be spared. By 2040, major heatwaves will be experienced by 50 per cent or more of the populations in West, Central, East and Southern Africa, the Middle East, South and Southeast Asia, as well as Central America and Brazil (Figure 4). By 2050, more than 70 per cent of people in every region will experience heatwaves.32 Urban areas will experience the greatest challenges of workability and survivability,33 due to urban heat island effects.

Figure 4. Proportion of regional populations experiencing major heatwaves, in 2040

— Source: Adapted from Arnell et al. (2019).

Africa and the Middle East

Across Africa and the Middle East, the projection under the central estimate is that more than 2.25 billion people will likely experience at least one heatwave of two or more consecutive days per year by 2050, exceeding 90 per cent of the population in all regions illustrated in Figure 5a–f. Major heatwaves of four consecutive days or more will be experienced across these regions, impacting more than 1.5 billion people – around two thirds of the population. For all these regions, major heatwaves will likely impact at least 10 times more people than if climate change were averted. West Africa is likely to be particularly impacted, with nearly half a billion people experiencing major heatwaves, 17 times more than if climate change were averted. Heatwaves in all these regions will also be felt over an increasing number of days per year. By 2050, North Africa is projected to be the least impacted, with 13 days per year of heatwaves; and Central Africa the most impacted, with 26 days. However, by 2100 the duration of heatwaves in Central Africa increases to over two months of the year for the central estimate, and almost seven months of the year for the high range of the estimate.

Figure 5. Populations within African regions and the Middle East experiencing heatwaves and major heatwaves

— Orange lines and areas represent heatwaves; red lines and areas represent major heatwaves. Shaded areas represent the lower and upper estimates of the given impact. Solid lines represent the central estimate. Dashed lines represent no additional climate change. Source: Adapted from Arnell et al. (2019).

Asia and Australasia

Across Asia (Figure 6a–d), the central estimate indicates that in excess of 4.2 billion people will likely experience heatwaves by 2050, equivalent to 90 per cent of the population. Across the most populous regions of South and East Asia, the central estimate indicates major heatwaves will impact more than 2 billion people in aggregate, around 60 per cent and 40 per cent of the population respectively. Relative to a scenario in which climate change is averted, Southeast Asia is projected to be most impacted, with over 13 times more people likely to experience major heatwaves. The duration of heatwaves also impacts Southeast Asia most heavily, with the central estimate indicating more than 25 days of heatwaves per year.

Figure 6. Populations within Asia and Australasia experiencing heatwaves and major heatwaves

The central estimate indicates more than 40 million people in Australasia34 (Figure 6e) are likely to experience heatwaves by 2050, equivalent to 80 per cent of the population. Major heatwaves are likely to impact over 22 times more people in 2050 than if climate change were averted, with over 10 days of heatwaves per year.

Europe

In Europe, as for Australasia, the impacts of heatwaves are felt by a relatively smaller proportion of the population compared with other regions. However, the central estimate for 2050 still indicates that more than 80 per cent of the population – i.e. over 0.6 billion people – are likely to experience heatwaves. Central Europe will be the most impacted (Figure 7b), with more than 90 per cent of the 2050 population, or just over 100 million people, experiencing heatwaves. Major heatwaves are most likely to impact the population of Western Europe (Figure 7a), with the central estimate indicating over 180 million people, 11 times more than if climate change were averted. By 2100, the central estimate indicates almost 16 days of heatwaves per year, but this could extend to as many as 35 days.

Figure 7. Populations within Europe experiencing heatwaves and major heatwaves

North, Central and South America

Figure 8. Populations within North, Central and South America experiencing heatwaves and major heatwaves

In North America,35 under the central estimate, more than 350 million and 40 million people across the US and Canada, respectively, are likely to experience heatwaves by 2050, respectively (Figure 8a&b), representing more than 85 per cent of the population of each country. The US is likely to be more severely impacted by major heatwaves, with 44 per cent of the population experiencing such events, as against 36 per cent in Canada. Compared to a scenario in which climate change is averted, both countries are likely to experience around 12 times more major heatwaves in 2050, with more than 13 per days per year of heatwaves in Canada, and over 20 days per year in the US.

Central America and Brazil (Figure 8c&d) are likely to be two of the most impacted regions, with the central estimate indicating that 95 per cent and 93 per cent of their respective populations will experience heatwaves by 2050. Across the whole of Central and South America, more than 670 million people will likely experience heatwaves, and in excess of 440 million – or 60 per cent of the population – are projected to experience major heatwaves. Across South and Central America, major heatwaves are likely to impact 10 times more people than if climate change were averted. Across Central and South America, by 2050, there are likely to be in excess of 20 days of heatwaves per year.

3.3 Food security

To meet global demand, agriculture will need to produce almost 50 per cent more food by 2050. However, yields could decline by 30 per cent in the absence of dramatic reductions in emissions.36 Between 1980 and 2019, global average crop yield potentials37 for maize, winter wheat, soybeans and rice have declined, with reductions of 5.6 per cent, 2.1 per cent, 4.8 per cent and 1.8 per cent, respectively.38 In recent years, regional drought and heatwaves have caused 20–50 per cent losses in crop harvests. In Australia, severe drought caused a 50 per cent collapse of wheat harvests two years in a row (2006 and 2007).39 In Europe, the 2018 heatwave led to multiple crop failures and yield losses of up to 50 per cent in Central and Northern Europe.40 During this period, Central Europe experienced severe drought across 52 per cent of the cropland area, where the threshold of severe drought is equivalent to the threshold of severe drought used here (Figure 9a&b and Figure 12). And in China, in Liaoning Province, drought years led to 20–25 per cent reductions in maize harvests.41 The global food crisis of 2007–08, caused by a conjunction of depleted grain stores, Australian drought and regional crop failures, led to a doubling of global food prices, export bans, food insecurity for importers, social unrest, and mass protests in at least 13 countries, including Cameroon, Egypt, Indonesia, Mexico, Morocco, Nepal, Peru, Senegal and Yemen.42, 43

By 2050 the central estimate indicates that nearly 40 per cent of global cropland area will be exposed to severe drought for three months or more each year.

Agricultural drought is a major cause of crop failure. Assuming global cropland remains constant at 14.7 million square kilometres, by 2050 the central estimate indicates that nearly 40 per cent of that area will be exposed to severe drought for three months or more each year;44 however, this could reach just over 50 per cent under the plausible worst-case scenario (Figure 9a). This vast area of stressed cropland is far higher than the 9 per cent of global cropland historically exposed to drought (1981–2010). Even by 2040, the average proportion of global cropland affected by severe drought will likely rise to 32 per cent each year, more than three times higher than the historic average.

Figure 9a. Proportion of global cropland experiencing severe drought of three months or more per year

— Shaded area represents the lower and upper estimates of the given impact. Solid line represents the central estimate. Source: Adapted from Arnell et al. (2019).

Figure 9b. Proportion of regional cropland exposed to severe drought, in 2050

Farmers in the worst-affected areas (Figure 9b), including the critical breadbasket regions of southern Russia and the US, are likely to experience agricultural drought impacting 40 per cent or more of their cropland area every year. By the 2040s, the probability of a 10 per cent yield loss, or greater, within the top four maize producing countries (the US, China, Brazil and Argentina) rises to 40–70 per cent. These countries together account for some 87 per cent of the world’s maize exports. The probability of a synchronous, greater than 10 per cent crop failure across all four countries is currently near zero, but this rises to around 6.1 per cent each year in the 2040s. The probability of a synchronous crop failure of this order during the decade of the 2040s is just less than 50 per cent.45, 46

The probability of a synchronous, greater than 10 per cent crop failure across all of the top four maize producing countries is currently near zero, but this rises to around 6.1 per cent each year in the 2040s. The probability of a synchronous crop failure of this order during the decade of the 2040s is just less than 50 per cent.

Wheat and rice form a major component of people’s diets, together comprising 37 per cent of average calorific intake per head globally.47 The central 2050 estimate (Figure 10a&b) indicates that more than 35 per cent of the global cropland used to grow both these critical crops will be subject to at least five days of damaging hot spells48 over their 30-day reproductive phase; but this could exceed 40 per cent in a plausible worst-case scenario. For comparison, 20 per cent and 27 per cent of winter wheat and rice areas, respectively, are currently under the same damaging hot spells.

As well as damaging hot spells of at least five days, agricultural crops will also have to deal with a reduction in crop duration periods.49 Damaging hot spells and reductions in crop duration periods can both reduce yields. The central estimate for 2050 indicates that significant proportions of global crop areas will be impacted by reductions in crop duration periods of at least 10 days, exceeding 45 per cent for maize, 50 per cent for soybeans, 60 per cent for winter wheat, 40 per cent for spring wheat, and 30 per cent for rice. Figure 11 indicates how the proportion of these croplands is impacted over time. It is important to note that, across these critical crops, the current global cropland area subject to reductions in crop duration periods is 5 per cent or less in all but one case; the exception is soybeans, currently around 7 per cent.

Figure 10a. Proportion of global winter wheat crop area experiencing damaging hot spells

Figure 10b. Proportion of global rice crop area experiencing damaging hot spells

— Shaded areas represent the lower and upper estimates of the given impact. Solid lines represent the central estimate. Source: Adapted from Arnell et al. (2019).

Figure 11. Proportion of global crop areas with reductions in crop duration periods of at least 10 days, by crop type

Continental agricultural impacts

Crop drought

As already highlighted, by 2050 the central estimate indicates that almost 40 per cent of global cropland will likely be exposed to severe drought each year.50 However, as the Asian continent contains 37 per cent of global cropland and a relatively low proportion of Asian cropland is subject to severe drought (just less than 30 per cent by 2050), it is crucial to investigate the continental impacts (Figure 12).

Europe has the second largest cropland area (20 per cent of the global total), and is likely to experience the largest increase in area affected by agricultural drought, with the central estimate indicating that nearly half the cropland area will experience severe periods of drought by 2050. Africa and North America have similar land areas dedicated to cropland: respectively 14 per cent and 15 per cent of the global total. However, Africa is likely to be more impacted, with almost 44 per cent of cropland projected to suffer severe drought, compared with 38 per cent for North America. Australasia is likely to be impacted to a similar extent as Europe, but only represents 2 per cent of global cropland.

Figure 12. Proportion of continental cropland experiencing severe drought of three months or more

Crop heat stress and duration reductions

At the global level, to 2050, damaging hot spells increase across winter wheat and rice croplands. However, relative to historic baselines, the cropland area impacted by reductions in crop duration periods is likely to be greater than the area impacted by increases in damaging hot spells. The same is true at the continental level, and is illustrated in Figure 13a–l. Across the six continents and five crop types shown in Table 1, this section focuses on those crop–continent combinations illustrated in Figure 13a–l that (a) in aggregate represent at least 10 per cent of a given continent’s cropland area; and (b) in aggregate represent at least 70 per cent of the global total of a given crop area.

Of those crop–continent combinations selected, shown in Table 1 and illustrated in Figure 13a–l, the predominant crops, by area, in Africa and Europe are maize (10 per cent) and winter wheat (16 per cent) respectively. Under the central estimate, more than 40 per cent of African maize growing areas are likely to be subject to reductions in crop duration periods of at least 10 days by 2050, up from 0.3 per cent historically (Figure 13i), while nearly 75 per cent of European winter wheat is subject to equally yield-reducing conditions (reductions in crop duration periods), up from almost 6 per cent historically.

Table 1. Cropland areas across crop types and continents. Highlighted entries are shown in Figure 13.

	Cropland areas, in thousand km2
	Maize	Winter wheat	Spring wheat	Rice	Soybeans	Total	Selection (% continent (a))
Global	1,335	1,721	415	788	744	14,719	–
Africa	219	64	14	54	9	2,124	10%
Asia	419	818	175	667	171	5,513	38%
Europe	136	491	36	4	11	3,009	16%
North America	302	150	180	13	306	2,185	36%
South America	259	81	10	50	247	1,573	32%
Australasia	1	118	0	1	0	315	38%
Selection (% global (b))	90%	83%	86%	85%	74%	–	–

(a) In aggregate representing at least 10 per cent of continent’s cropland area. (b) In aggregate representing at least 70 per cent of the global total of crop area.

Maize, winter wheat and spring wheat make up around 38 per cent of Asian croplands. Figure 13a–d illustrates the reductions in crop duration periods across these crops. In aggregate, 40 per cent of the growing area is likely to be subject to reductions in crop duration periods of at least 10 days by 2050, with winter wheat the most impacted (over 50 per cent) under the central estimate. Similarly, in aggregate, just less than 60 per cent of North American maize, spring wheat and soybeans are likely to be subject to such yield reducing conditions (Figure 13e, g&h), with these crops making up 36 per cent of North American cropland areas.

Turning to South America, in aggregate, just less than half of maize and soybean croplands are likely to suffer reduced crop duration periods (Figure 13k&l) by 2050, with these crops accounting for 32 per cent of South American cropland areas. Finally, in Australasia, again under the central estimate, more than 90 per cent of winter wheat growing areas will be to be subject to reductions in crop duration periods (Figure 13j), with winter wheat representing 38 per cent of Australasian cropland.

Figure 13. Proportion of the largest areas, for different crops per continent (across five crop types), with reductions in crop duration periods of at least 10 days, and experiencing damaging hot spells

— Dark green lines and areas represent hot spells; bright green represent reductions in crop duration periods. Shaded areas represent the lower and upper estimates of the given impact. Solid lines represent the central estimate. Source: Adapted from Arnell et al. (2019).

Agricultural yields

Crop yields are likely to be reduced by the conditions represented by the three impact indicators of agricultural drought, shorter crop durations51 and heat stress,52 presented in the previous sections. The thresholds of impact for these crop impact indicators are set at a level where crossing these thresholds is damaging to crop yields.53 The dramatic increase in frequency and probability of these extreme events in all regions even under the central estimate – let alone under the plausible worst-case scenario – indicates that yields could be dramatically reduced. While probabilistic estimates for crop yields are not made directly here, it remains plausible that multiple breadbaskets may suffer simultaneous effects, with the potential to drive significant reduction in yields at global as well as regional levels.

It remains plausible that multiple breadbaskets may suffer simultaneous effects, with the potential to drive significant reduction in yields at global as well as regional levels.

The 2007–08 and 2010–11 food price spikes arose from relatively modest climate impacts interacting with other factors (e.g. biofuel policy diverting grain to ethanol, low stock transparency), which created a run on grain markets, in turn leading to the implementation of export bans, and thus further amplifying the price effect. The consequences for global food prices, availability and associated food riots around the world is well known. The impacts of climate change will likely compound these risks in the average year of the coming decades. It should be noted, too, that the impact indicators of the previous sections are not representative of extreme outlier events, such as megadroughts, nor of the impacts of interacting or compounding risks that are likely to occur as multiple risks interact.

3.4 Water security

Hydrological drought poses a significant risk on the global scale (Figure 14a). Long droughts are one of the most significant environmental causes of premature mortality, impacting sanitation and hygiene, increasing malnutrition, and reducing crop yields.54 Over twice the global land area was affected by drought in 2019, compared with the historic baseline. In the Sahel in 2020, some 13.4 million people in Mali, Niger and Burkina Faso were reported as being affected by drought, and in need of humanitarian assistance; and the region’s security crisis, in part driven by shocks related to climate change, has caused some 2.7 million people to flee their homes.55 In the US drought of 2012, natural disasters were declared in 71 per cent of the country’s counties, and a reduction in GDP growth of 0.5–1 percentage point was forecast.56 In China’s Yunnan Province, the 2020 drought affected 1.5 million people. 180 reservoirs in the province dried up, 100 rivers were cut off, and 140 irrigation wells lacked sufficient water supply.57

Figure 14a. Global population experiencing a drought of at least six months with 12-month accumulated Standardized Runoff Index of less than -1.5

— Shaded area represents the lower and upper estimates of the given impact. Solid line represents the central estimate. Dashed line represents no additional climate change. Source: Adapted from Arnell et al. (2019).

By 2040, the central estimate indicates almost 700 million people each year will be exposed to hydrological droughts of at least six months’ duration.58 This represents a near doubling of the historic annual average of 408 million people subjected to long periods of drought. The severity and length of these future droughts are projected to be at least as bad as the first wave (1934) of the US Midwest ‘dust bowl’ drought of the 1930s.59

It should be noted that this paper does not present a quantification of the likelihood of megadroughts. One recent study has shown such a multi-decadal drought in southwestern North America in 2000–18 was the most severe since medieval megadroughts (late 1500s), and the second driest 19-year period since 800 CE.60

Figure 14b. Proportion of regional populations experiencing drought, in 2040

Continental and regional drought

Heatwaves and increased temperatures place greater stress on the availability of water regionally. No region will be spared, but by 2040 East and South Asia will be most impacted, with 125 million and 105 million people respectively experiencing prolonged hydrological drought. In Africa, 152 million people each year will be impacted. As Figure 14b shows, more than 10 per cent of the populations of North Africa, the Middle East, Western and Central Europe, and Central America will all be impacted by prolonged drought.

Figure 15 illustrates the populations, by continent, likely to experience droughts of at least six months’ duration to the end of this century. Whereas by 2050 the population of Asia is likely to be most impacted, with more than 360 million people affected, this is a relatively low (although nonetheless troubling) 17 per cent increase relative to a scenario in which climate change is averted. Europe and South America are likely to see the greatest increase in this regard by 2050, at more than 120 per cent and nearly 90 per cent respectively. Setting Asia aside, the continent with the greatest number of people likely to be impacted by hydrological drought is Africa, exceeding 180 million by 2050 under the central estimate. Africa is also likely to suffer the greatest increase of people experiencing drought relative to the historic baseline (1981–2010), by 290 per cent from just below 63 million. This increase relative to the historic baseline is similar across all regions of the African continent. At regional level, the Middle East and Central America will each likely experience increases exceeding 300 per cent relative to the past under the central estimate, and in absolute terms affecting over 40 and 35 million people by 2050, respectively.

Figure 15. Populations experiencing a drought of at least six months with 12-month accumulated Standardized Runoff Index of less than -1.5, by continent

Drought is a relative measure of water availability, and does not necessarily relate to the absolute amount of water per person. As such, it is useful also to consider water stress. North Africa and the Middle East are likely to have the greatest proportion of their populations experiencing severe water stress (i.e. availability of less than 500 cubic metres per head per year), at 17 per cent and 14 per cent, respectively, in 2050. As Figure 16 illustrates, many regions of the world are likely to see 40 per cent or greater increases in the difference between supply and demand of water by 2040, relative to the historic baseline.

Figure 16. Regions of increasing water stress (demand relative to supply) in 2040, relative to 2019

— Source: World Resources Institute, Aqueduct Water Risk Atlas.

Regional coastal and river flooding

In 2020, there were 23 per cent more floods recorded than the annual average of 163 events in 2000–19, and 18 per cent more flood deaths than the annual average of 5,233.61 One billion people are now living on land less than 10 metres above current high tide lines, with 230 million of these on land below 1 metre.62

The impacts of coastal flooding are likely to occur over a longer time horizon than many other climate risks. The long-term central estimate of committed sea level rise is around 12 metres, if temperatures are held at 2°C. The timeframes are extremely uncertain: this could occur over 500 years or 10,000 years.63 A 1 metre rise in relative sea level increases the probability of current 100-year flood events by around 40 times in Shanghai, around 200 times in New York, and around 1,000 times in Kolkata.64

Figure 17. Committed sea level rise as a function of long-term global temperature increase

— Source: Adapted from Fig. 13.14 from IPCC (2013).65

Given current understanding, the central estimate suggests that by 2100 nearly 200 million people worldwide will be living below the 100-year flood level. However, if the rate of Antarctic ice melt continues at the accelerated rate of recent years, this is likely to be an underestimate (the rate of ice loss from Antarctica has tripled since 2012, relative to the previous two decades).66 The impacts of coastal flooding are most likely to be suffered by populations in Asia. Figure 18a–c illustrates the annual number of people likely to be impacted, where it is assumed that coastal flood defences are designed to cope with sea levels of the period 1986–2005. By 2100, 30 million per year are projected to be impacted in South Asia, 25 million in East Asia and more than 20 million in Southeast Asia. In aggregate, across these three regions, around 11 times more people will be impacted by coastal flooding than under a scenario in which climate change is averted. River flooding also poses a risk in South Asia, with the central estimate indicating around 33 million people are likely to be impacted; however, as many as 86 million could be affected in a worst-case scenario.67 It should be noted that this assumes no river flood defences are built, where the threshold of impact indicator is a river flood greater than the historic baseline (once in 50 years) flooding.

Figure 18. Populations in selected regions likely to experience coastal and river flooding

Arnell, N. W., Lowe, J. A., Bernie, D., Nicholls, R. J., Brown, S., Challinor, A. J. and Osborn, T. J. (2019), ‘The global and regional impacts of climate change under representative concentration pathway forcings and shared socioeconomic pathway socioeconomic scenarios’, Environmental Research Letters, 14(8), 084046, doi:10.1088/1748-9326/ab35a6 (accessed 13 Aug. 2021).

For greater detail on the uncertainty associated with the direct risk impacts, as well as definitions of thresholds of impact, see Arnell et al. (2019).

Sharpe, S. (2019), ‘Telling the boiling frog what he needs to know: why climate change risks should be plotted as probability over time, Geoscience Communication, 2(1), pp. 95–100, doi:10.5194/gc-2-95-2019 (accessed 13 Aug. 2021).

Arnell et al. (2019), ‘The global and regional impacts of climate change under representative concentration pathway forcings and shared socioeconomic pathway socioeconomic scenarios’.

Arnell et al. (2019) use SSP population projections downscaled to the 0.5°×0.5° resolution by Jones and O’Neill (2016), as well as country GDP projections from Dellink et al. (2017), downscaled to the same resolution in order to quantify exposure. For more details see Arnell et al. (2019).

O’Neill, B. C., Kriegler, E., Ebi, K. L., Kemp-Benedict, E., Riahi, K., Rothman, D.S., van Ruijven, B. J., van Vuuren, D. P., Birkmann, J., Kok, K., Levy, M. and Solecki, W. (2017). ‘The roads ahead: Narratives for shared socioeconomic pathways describing world futures in the 21st century’, Global Environmental Change, 42: pp. 169–180, doi:10.1016/j.gloenvcha.2015.01.004 (accessed 13 Aug. 2021).

Ibid.

Coupled Model Intercomparison Project Phase 5.

Lenton, T. M., Rockström, J., Gaffney, O., Rahmstorf, S., Richardson, K., Steffen, W. and Schellnhuber, H. J. (2019), ‘Climate tipping points – too risky to bet against’, Nature, 575(7784): pp. 592–595, doi:10.1038/d41586-019-03595-0 (accessed 13 Aug. 2021).

Drijfhout, S., Bathiany, S., Beaulieu, C., Brovkin, V., Claussen, M., Huntingford, C., Scheffer, M., Sgubin, G. and Swingedouw, D. (2015), ‘Catalogue of abrupt shifts in Intergovernmental Panel on Climate Change climate models’, Proceedings of the National Academy of Sciences, 112(43): pp. E5777–E5786, doi:10.1073/pnas.1511451112 (accessed 13 Aug. 2021).

Lenton et al. (2019), ‘Climate tipping points – too risky to bet against’.

IPCC (2013), Climate Change 2013: The Physical Science Basis, Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge and New York: Cambridge University Press.

Wunderling, N., Donges, J. F., Kurths, J. and Winkelmann, R. (2021), ‘Interacting tipping elements increase risk of climate domino effects under global warming’, Earth System Dynamics, 12(2), pp. 601–619, doi:10.5194/esd-12-601-2021 (accessed 13 Aug. 2021).

Ibid.

Watts, N. et al. (2021), ‘The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises’, The Lancet, 397(10269): pp. 129–170, doi:10.1016/S0140-6736(20)32290-X (accessed 13 Aug. 2021).

International Labour Organization (2021), ‘ILO Monitor: COVID-19 and the world of work. Seventh edition’, ILO Data Explorer, https://www.ilo.org/shinyapps/bulkexplorer39/?lang=en&segment=indicator&id=HOW_ 2LSS_NOC_RT_A (accessed 1 May 2021).

Watts, N. et al. (2019), ‘The 2019 report of The Lancet Countdown on health and climate change: ensuring that the health of a child born today is not defined by a changing climate’, The Lancet, 394(10211): pp. 1836–1878, doi:10.1016/S0140-6736(19)32596-6 (accessed 13 Aug. 2021).

Watts et al. (2021), ‘The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises’.

Workability threshold: the monthly mean of daily maximum wet-bulb globe temperature exceeds 34°C.

Survivability threshold: the maximum daily wet-bulb globe temperature exceeds 40°C for three consecutive days.

Andrews, O., Le Quéré, C., Kjellstrom, T., Lemke, B. and Haines, A. (2018), ‘Implications for workability and survivability in populations exposed to extreme heat under climate change: a modelling study’, The Lancet Planetary Health, 2(12), pp. e540–e547, doi:10.1016/s2542-5196(18)30240-7 (accessed 13 Aug. 2021).

Converted Andrews et al. (2018) temperature thresholds to timeframes, based on RCP4.5 passing relevant temperature thresholds, based on CMIP6 climate models. See https://esd.copernicus.org/articles/12/253/2021/esd-12-253-2021-discussion.html and https://www.carbonbrief.org/analysis-when-might-the-world-exceed-1-5c-and-2c-of-global-warming.

Arnell et al. (2019), ‘The global and regional impacts of climate change under representative concentration pathway forcings and shared socioeconomic pathway socioeconomic scenarios’.

By definition, a heatwave requires the temperature to exceed the 98th percentile of the historic reference period (1981–2010); a major heatwave exceeds the 99th percentile.

Arnell et al. (2019), ‘The global and regional impacts of climate change under representative concentration pathway forcings and shared socioeconomic pathway socioeconomic scenarios’.

Andrews et al. (2018), ‘Implications for workability and survivability in populations exposed to extreme heat under climate change: a modelling study’.

Australasia is defined in the source analysis (Arnell et al., 2019) as including Australia, New Zealand, Papua New Guinea and the Pacific islands.

Mexico and the Caribbean islands are included in the source analysis (Arnell et al., 2019) as part of Central America.

Global Commission on Adaptation (2019), Adapt Now: A Global Call For Leadership On Climate Resilience, Rotterdam: Global Commission on Adaptation, https://gca.org/reports/adapt-now-a-global-call-for-leadership-on-climate-resilience (accessed 13 Aug. 2021).

Crop yield potential is characterized by ‘crop growth duration’ (the time taken to reach a target sum of accumulated temperatures) over its growing season. If this sum is reached early, the crop matures too quickly and yields are lower than average, with a reduction in crop growth duration therefore representing a reduction in yield potential.

Watts et al. (2021), ‘The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises’.

Index Mundi (2021), ‘Australia Wheat Production by Year’, https://www.indexmundi.com/agriculture/ ?country=au&commodity=wheat&graph=production (accessed 13 Jun. 2021).

Beillouin, D., Schauberger, B., Bastos, A., Ciais, P. and Makowski, D. (2020), ‘Impact of extreme weather conditions on European crop production in 2018’, Philosophical Transactions of the Royal Society B: Biological Sciences, 375(1810): p.20190510, doi:10.1098/rstb.2019.0510 (accessed 13 Aug. 2021). Toreti, A., Belward, A., Perez-Dominguez, I., Naumann, G., Luterbacher, J., Cronie, O., Seguini, L., Manfron, G., Lopez-Lozano, R., Baruth, B., Berg, M., Dentener, F., Ceglar, A., Chatzopoulos, T. and Zampieri, M. (2019), ‘The Exceptional 2018 European Water Seesaw Calls for Action on Adaptation’, Earth’s Future, 7(6): pp. 652–663, doi:10.1029/2019ef001170 (accessed 13 Aug. 2021).

Chen, T., Xia, G., Liu, T., Chen, W. and Chi, D. (2016), ‘Assessment of Drought Impact on Main Cereal Crops Using a Standardized Precipitation Evapotranspiration Index in Liaoning Province, China’, Sustainability, 8(10): p. 1069, doi:10.3390/su8101069 (accessed 13 Aug. 2021).

Wright, B. D. (2011), ‘The Economics of Grain Price Volatility’, Applied Economic Perspectives and Policy, 33(1): pp. 32–58, doi:10.1093/aepp/ppq033 (accessed 13 Aug. 2021). Spiegel International (2008), ‘Global Food Crisis: The Fury of the Poor’, 14 April 2008, https://www.spiegel.de/international/world/global-food-crisis-the-fury-of- the-poor-a-547198.html (accessed 13 Jun. 2021).

United Nations (2012), Report on the World Social Situation 2011: The Global Social Crisis, New York: United Nations, pp. 61–74, https://www.un-ilibrary.org/content/books/9789210552226 (accessed 13 Aug. 2021).

A severe drought is a period of at least three months with a SPEI-6 less than -1.5. SPEI: Standardised Precipitation-Evapotranspiration Index (SPEI: Vicente-Serrano et al., 2010).

Tigchelaar, M., Battisti, D. S., Naylor, R. L. and Ray, D. K. (2018), ‘Future warming increases probability of globally synchronized maize production shocks’, Proceedings of the National Academy of Sciences, 115(26): pp. 6644–6649, doi:10.1073/pnas.1718031115 (accessed 13 Aug. 2021).

Converted Tigchelaar et al. (2018) temperature thresholds to timeframes, based on RCP4.5 passing relevant temperature thresholds, based on CMIP6 climate models. See https://esd.copernicus.org/articles/12/253/2021/esd-12-253-2021-discussion.html and https://www.carbonbrief.org/analysis-when-might-the-world-exceed-1-5c- and-2c-of-global-warming. Further, converted annual likelihood of 6.1 per cent to probability decadal probability  of occurrence.

FAO (2017), FAOSTAT data, http://www.fao.org/faostat/en/#home (accessed 14 Aug. 2021).

A hot spell consists of at least five days above a heat stress threshold (Table S1) during the 30-day reproductive phase of the crop, with the heat stress thresholds taken from Gourdji et al., 2013. The reproductive season is based on planting dates (Sacks et al., 2010) which are assumed not to change over time.

This is defined (following Challinor et al., 2016) on the basis of the accumulated thermal time (ATT) over the growing season, where the ATT is the sum of temperatures above a minimum temperature and capped at an optimum temperature.

Cropland areas are assumed to remain constant.

Challinor, A. J., Koehler, A.-K., Ramirez-Villegas, J., Whitfield, S. and Das, B. (2016), ‘Current warming will reduce yields unless maize breeding and seed systems adapt immediately’, Nature Climate Change, 6(10): pp. 954–958, doi:10.1038/nclimate3061 (accessed 13 Aug. 2021).

Gourdji, S. M., Sibley, A. M. and Lobell, D. B. (2013), ‘Global crop exposure to critical high temperatures in the reproductive period: historical trends and future projections’, Environmental Research Letters, 8(2): 024041, doi:10.1088/1748-9326/8/2/024041 (accessed 13 Aug. 2021).

See Arnell et al. (2019) for further details on these thresholds as well as the previous section descriptions of these thresholds.

Smith, K. R., Woodward, A., Campbell-Lendrum, D., Chadee, D. D., Honda, Y., Liu, Q., Olwoch, J. M., Revich, B. and Sauerborn, R. (2014), ‘Human Health: Impacts, Adaptation, and Co-Benefits’, in Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects, Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge and New York: Cambridge University Press.

Watts et al. (2021), ‘The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises’. UNHCR (2020), ‘Sahel Crisis Explained’, https://www.unrefugees.org/news/sahel-crisis-explained (accessed 11 Jun. 2021). CRED and UNDRR (2020), The Non-COVID Year in Disasters, Brussels: CRED, https://reliefweb.int/report/world/2020-non-covid-year-disasters-global-trends-and-perspectives (accessed 11 Jun. 2021).

Richter, J. (2012), ‘U.S. Drought May Cut GDP by 1 Percentage Point, Deutsche Says’, Bloomberg, 12 November 2012, https://www.bloomberg.com/news/articles/2012-11-12/u-s-drought-may-cut-gdp-by-one-percentage-point-deutsche-says (accessed 11 Jun. 2021). USDA (2013), ‘USDA Designates 597 Counties in 2013 as Disaster Areas Due to Drought’, U.S. Department of Agriculture, 9 January 2013, https://www.usda.gov/media/press-releases/2013/01/09/usda-designates-597-counties-2013-disaster-areas-due-drought (accessed 1 May 2021).

CGTN (2020), ‘Chinese plateau province sees worst drought in 10 years’, China Global Television Network, 18 April 2020, https://news.cgtn.com/news/2020-04-18/Chinese-plateau-province-sees-worst-drought-in-10-years-PMGdSN543e/index.html (accessed 1 May 2021).

Hydrological drought: a period of at least six months with 12-month accumulated Standardized Runoff Index (SRI) of less than -1.5. (SRI: Shukla and Wood 2008.)

Mishra, V., Cherkauer, K. A. and Shukla, S. (2010), ‘Assessment of Drought due to Historic Climate Variability and Projected Future Climate Change in the Midwestern United States’, Journal of Hydrometeorology, 11(1): pp. 46–68, doi:10.1175/2009jhm1156.1 (accessed 13 August 2021).

Williams, A. P., Cook, E. R., Smerdon, J. E., Cook, B. I., Abatzoglou, J. T., Bolles, K., Baek, S. H., Badger, A. M. and Livneh, B. (2020), ‘Large contribution from anthropogenic warming to an emerging North American megadrought’, Science, 368(6488): pp. 314–318, doi:10.1126/science.aaz9600 (accessed 13 Aug. 2021).

CRED (2021), ‘CRED Crunch Newsletter, Issue No. 62 (May 2021) – Disaster Year in Review 2020: Global Trends and Perspectives’, https://reliefweb.int/report/world/cred-crunch-newsletter-issue-no-62-may-2021-disaster-year-review-2020-global-trends-and (accessed 7 Jun. 2021).

Kulp, S. A. and Strauss, B. H. (2019), ‘New elevation data triple estimates of global vulnerability to sea-level rise and coastal flooding’, Nature Communications, 10(1), doi:10.1038/s41467-019-12808-z (accessed 13 Aug. 2021).

King, D. et al. (2017), Climate Change: A Risk Assessment.

Ibid.

IPCC (2013), Climate Change 2013: The Physical Science Basis.

Slater, T., Lawrence, I. R., Otosaka, I. N., Shepherd, A., Gourmelen, N., Jakob, L., Tepes, P., Gilbert, L. and Nienow, P. (2021), ‘Review article: Earth’s ice imbalance’, Cryosphere, 15(1): pp. 233–246, doi:10.5194/tc-15-233-2021 (accessed 13 Aug. 2021).

Average annual number of people exposed to a river flood greater than the reference period 50-year flood (1981–2010).

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Climate change risk assessment 2021

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03 Direct climate impacts

3.1 Approach: how to understand the impacts presented

Box 2. Tipping points

3.2 Heat, productivity and health

Figure 2. Number of people exposed to heat stress above the risks to workability and survivability thresholds at a given change in global mean surface temperature relative to pre-industrial levels

Figure 2. Number of people exposed to heat stress above the risks to workability and survivability thresholds at a given change in global mean surface temperature relative to pre-industrial levels

Figure 3a. Global population experiencing a heatwave that exceeds the 98th percentile of the reference period (1981–2010) for two or more consecutive days per year

Figure 3a. Global population experiencing a heatwave that exceeds the 98th percentile of the reference period (1981–2010) for two or more consecutive days per year

Figure 3b. Global population experiencing a major heatwave that exceeds the 99th percentile of the reference period (1981–2010) for four or more consecutive days per year

Figure 3b. Global population experiencing a major heatwave that exceeds the 99th percentile of the reference period (1981–2010) for four or more consecutive days per year

Regional heatwaves

Figure 4. Proportion of regional populations experiencing major heatwaves, in 2040

Figure 4. Proportion of regional populations experiencing major heatwaves, in 2040

Africa and the Middle East

Figure 5. Populations within African regions and the Middle East experiencing heatwaves and major heatwaves

Figure 5. Populations within African regions and the Middle East experiencing heatwaves and major heatwaves

Asia and Australasia

Figure 6. Populations within Asia and Australasia experiencing heatwaves and major heatwaves

Figure 6. Populations within Asia and Australasia experiencing heatwaves and major heatwaves

Europe

Figure 7. Populations within Europe experiencing heatwaves and major heatwaves

Figure 7. Populations within Europe experiencing heatwaves and major heatwaves

North, Central and South America

Figure 8. Populations within North, Central and South America experiencing heatwaves and major heatwaves

Figure 8. Populations within North, Central and South America experiencing heatwaves and major heatwaves

3.3 Food security

Figure 9a. Proportion of global cropland experiencing severe drought of three months or more per year

Figure 9a. Proportion of global cropland experiencing severe drought of three months or more per year

Figure 9b. Proportion of regional cropland exposed to severe drought, in 2050

Figure 9b. Proportion of regional cropland exposed to severe drought, in 2050

Figure 10a. Proportion of global winter wheat crop area experiencing damaging hot spells

Figure 10a. Proportion of global winter wheat crop area experiencing damaging hot spells

Figure 10b. Proportion of global rice crop area experiencing damaging hot spells

Figure 10b. Proportion of global rice crop area experiencing damaging hot spells

Figure 11. Proportion of global crop areas with reductions in crop duration periods of at least 10 days, by crop type

Figure 11. Proportion of global crop areas with reductions in crop duration periods of at least 10 days, by crop type

Continental agricultural impacts

Crop drought

Figure 12. Proportion of continental cropland experiencing severe drought of three months or more

Figure 12. Proportion of continental cropland experiencing severe drought of three months or more

Crop heat stress and duration reductions

Table 1. Cropland areas across crop types and continents. Highlighted entries are shown in Figure 13.

Figure 13. Proportion of the largest areas, for different crops per continent (across five crop types), with reductions in crop duration periods of at least 10 days, and experiencing damaging hot spells

Figure 13. Proportion of the largest areas, for different crops per continent (across five crop types), with reductions in crop duration periods of at least 10 days, and experiencing damaging hot spells

Agricultural yields

3.4 Water security

Figure 14a. Global population experiencing a drought of at least six months with 12-month accumulated Standardized Runoff Index of less than -1.5

Figure 14a. Global population experiencing a drought of at least six months with 12-month accumulated Standardized Runoff Index of less than -1.5

Figure 14b. Proportion of regional populations experiencing drought, in 2040

Figure 14b. Proportion of regional populations experiencing drought, in 2040

Continental and regional drought

Figure 15. Populations experiencing a drought of at least six months with 12-month accumulated Standardized Runoff Index of less than -1.5, by continent

Figure 15. Populations experiencing a drought of at least six months with 12-month accumulated Standardized Runoff Index of less than -1.5, by continent

Figure 16. Regions of increasing water stress (demand relative to supply) in 2040, relative to 2019

Figure 16. Regions of increasing water stress (demand relative to supply) in 2040, relative to 2019

Regional coastal and river flooding

Figure 17. Committed sea level rise as a function of long-term global temperature increase

Figure 17. Committed sea level rise as a function of long-term global temperature increase

Figure 18. Populations in selected regions likely to experience coastal and river flooding

Figure 18. Populations in selected regions likely to experience coastal and river flooding