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1 - Climate Extremes, Climate Attribution, Extreme Event Attribution

Published online by Cambridge University Press:  01 June 2021

Chris C. Funk
University of California, Santa Barbara


Beginning in northwestern Kenya with the story of Eregae and Aita Nakali, this chapter introduces the new science of climate extremes and extreme event attribution. Between 2015 and 2019, the “fingerprints” of climate change slapped hundreds of millions of people. Extreme heat waves, floods, droughts, and wildfires exacted a terrible toll on developed and developing nations alike. These catastrophes affected hundreds of millions of people and resulted in hundreds of billions of dollars in losses. Fire-afflicted movie stars in California and ranchers in Australia; drought-stricken South Africans; poor flooded fisher-folk in Bangladesh; Houston's middle-class families riven by flood: these are just some of the people who felt the crushing blow of more extreme climate. While humans have always faced the perils of natural disasters, the data suggest that the human and economic cost of climate and weather extremes is increasing rapidly as our population and economies expand and our planet warms rapidly. Since the early 1980s, the number of large catastrophes has quadrupled, inflicting billions of dollars in losses and impacting vulnerable populations on every continent. Understanding the link between extremes and warming is both a moral and an existential imperative.

Drought, Flood, Fire
How Climate Change Contributes to Catastrophes
, pp. 1 - 20
Publisher: Cambridge University Press
Print publication year: 2021


Drought. Fire. Flood. Words that echo through our calamitous past and collective future. Words that threaten to rip our everyday day away, to tear our normal lives apart.

Anticipating, managing, and preventing such disasters has always been a critical test of civilizations. A test of our shared humanity.

Consider, for example, the story of Eregae Lokeno Nakali, shared with me in 2017 by Mathilde Berg Utzon.Footnote 1 Mathilde worked as an Africa correspondent for DanChurchAid, a Danish humanitarian nongovernmental organization (NGO) dedicated to supporting the world’s poorest people. Driven by compassion, DanChurchAid works to create a more equitable and sustainable world. They provide emergency relief in disaster-stricken areas and long-term development assistance for poverty-stricken communities. Together with Action by Churches Together Alliance, DanChurchAid works in 130 countries to provide about $1.5 billion in humanitarian assistance each year.

Mathilde and I connected via e-mail in 2017. She was spending a lot of time in East Africa. I spend a lot of time looking at East Africa on my computer screen, working with the US Agency for International Development’s Famine Early Warning Systems Network (FEWS NET, East Africa is one of the most food-insecure places in the world.

In 2017, I had recently started blogging about East African droughts and their relation to climate change.Footnote 2

Mathilde had recently traveled to Turkana County in northwestern Kenya, to document the severe drought that region was experiencing. There she met Eregae Lokeno Nakali (Figure 1.1). Eregage is eighty-one years old. Mathilde writes, “his look is intense and friendly. Between his chin and his lower lip he has a round, silver coloured piece of jewelry. His cheeks are sunken and the wrinkles are deep. It bears witness to a long life. He has experienced how a wealthy life with three wives and enough food has been replaced by extreme poverty and daily uncertainty.”

Figure 1.1 Eregae Lokeno Nakali. Photograph by Mathilde Berg Utzon.

The seminomadic pastoralists of Turkana have evolved a way of life that is, in good times, well suited to their barren surroundings. They raise herds of livestock that can capitalize on sporadic episodes of rain, turning this precious moisture into milk and meat. But Eregae tells Mathilde that in the last year and half there has been almost no rain. He tells Mathilde that he has lost his wife, sister, and daughter due to disease attacking their starved bodies. Eregae and his neighboring villagers have seen their livestock herds destroyed. Eregae takes Mathilde to see the grave of his daughter (Figure 1.2). Mathilde describes the scene:

Sand coloured, brown and grey stones the size of a fist lie placed in a row in a light brown sandy landscape. Around the stone pattern lie dried branches that the wind has spread randomly across the landscape. This is where Eregae’s daughter Napua Eregae lies buried. Only a local person from the area could point out her grave, which is almost invisible in the surroundings.

It was in May last year that her body gave up to hunger. Eregae had no food to give her, and he couldn’t afford to take her to the hospital that was too far away. He explains that he couldn’t do anything while his daughter died before his eyes.

“It was terrible. I found it very difficult,” Eregaye says.

And as though it was not enough for Eregae Lokeno Nakali to lose three of his closest family members, he has also lost his wealth, his identity and employment. All because of the drought and almost no help from outside.

Unfortunately, East African droughts like the ones that afflicted Eregae and Aita are becoming more common. What used to be a one-in-five-years drought now often happens every third year or so. And now warmer air temperatures accompany poor rainy seasons in regions that are already very hot. This heat can exacerbate the atmosphere’s ability to pull moisture from the soil and vegetation, desiccating plants and weakening life-sustaining herds of livestock. These more frequent hotter droughts prevent families like Eregae’s from accumulating wealth. More frequent disasters sap resilience, enforcing a crushing cycle of poverty. In a poor year these households’ herds of goats, sheep, cows, or camels may be destroyed, a huge financial loss for people often living on close to $1 a day.

Eregae and Aita live in the arid Turkana region near the northwestern tip of Kenya. Since Mathilde visited in 2017, the region has been wracked by weather extremes. In the main March–May rainy season of 2018, severe floods in this region and other parts of Kenya displaced more than 300,000 people and led directly to some 132 deaths.Footnote 3 Then, in the next October–December 2018 “short” rainy season, the rains came late and were well below normal. Crop production was dismal, about 30 percent of average. Milk production from livestock (a key source of nutrition) dropped by 50 percent. The March–May rains of 2019 were once again below normal, and the region once again faced extreme hunger, conditions right on the border of famine.Footnote 4

As a scientist supporting FEWS NET, these are the poor people I try to protect. Every year, NGOs such as DanChurchAid and government agencies such as FEWS NET and the World Food Programme (WFP) provide billions of dollars in humanitarian assistance to people like Eregae and Aita. These efforts are largely successful at minimizing loss of life. But the number of severely food-insecure people in the world is growing rapidly, and our ability to limit economic devastation remains very limited.

Mathilde and I work at opposite ends of a spectrum of international experts dedicated to preventing, or at least responding to, international disasters in the developing world. Mathilde works with a faith-based NGO helping motivate charitable interventions. I am a hard-core academic at the University of California, Santa Barbara, specializing in using satellites and computers to identify and predict climate hazards. Mathilde works with people. I look at data. We both try to help people like Eregae’s young daughter Aita Eregae Nakali (Figure 1.2). I share Mathilde’s story with you because it conveys, in ways that my numbers, charts, and maps cannot, the human cost of climate extremes. Climate change is making climate extremes more frequent and intense, not just in Kenya, or in Africa in general, but on every continent. Not in the future, but right now.

Figure 1.2 Eregae’s young daughter Aita Eregae Nakali.

Photograph by Mathilde Berg Utzon

Every day I work on predicting and monitoring climate hazards. I follow the weather and climate closely, designing and developing information systems that help humanitarian relief agencies save lives and livelihoods. Like a doctor, or a drought detective, I diagnose the factors driving extreme events, so I can improve our capacity to monitor and predict them. I never wanted to study climate change, but it crept into my office like an unwelcome guest, like the coal dust lurking behind a miner’s black lungs. Twenty years of data-driven diagnoses brings me to this book. Climate change is hurting people like Aita Eregae.

Over the past few years (2015–2020), the “fingerprints” of climate change have seemed more like a slap. Extreme heat waves, floods, droughts, and wildfires have exacted a terrible toll on developed and developing nations alike. These extremes have impacted hundreds of millions of people and resulted in hundreds of billions of dollars in losses, all across the globe. Fire-afflicted movie stars in California; conflagration ravaged ranchers in Australia; drought-stricken South Africans; poor flooded fisherfolk in Bangladesh; Houston’s middle-class families riven by flood – these are just some of the people who have felt the crushing blow of more extreme climate.

But early warning systems can anticipate these disasters, helping to save lives and livelihoods. Such foresight depends on attention and understanding. Viewing the world in an informed way can open the door to a more meaningful and careful life. Perception is a function of both sensory input and our internal conceptions about how the world works. Perceiving the contribution that climate change is making to real-world disasters can clarify our moral, rational, economic, and existential imperatives. My goal here is to provide a data-driven “climate change toolkit” that you can use to see for yourself the influence of climate change on real-world weather and climate extremes. Along the way we will also learn a lot of neat stuff about our beautiful planet. Understanding how our miraculous mothership works can only enrich all our lives.

Exploring Recent Extremes

Since global temperatures jumped up the 2015/16 El Niño, the world has experienced a dramatic increase in the number of extreme events. Climate risks arise through the interaction of climate shocks, exposure, and vulnerability. Climate shocks in turn are comprised of natural and human-induced (anthropogenic) components. So untangling the specific contribution of climate change to multiple extreme events is extremely difficult, and beyond the scope of this book. But we can learn how, in general, climate change is influencing these events. There is little doubt that climate risk is rapidly increasing. Figure 1.3 shows the number of extreme events between 1980 and 2018, based on the Munich Re reinsurance company’s Natural Catastrophe database.Footnote 5

Figure 1.3 The number of extreme events for each year, based on the Munich Re reinsurance company’s Natural Catastrophe database.

Reinsurance companies insure insurance companies, helping regular insurance companies cope with the huge potential losses associated with severe events like floods and fires. So companies like Munich Re track the number of different weather-related disasters closely. For these companies, such information is critical to their survival. What should be concerning to all of us is that the frequency of such events appears to have more than tripled since the early 1980s. Each vertical bar in Figure 1.3 shows the number of big weather-related catastrophes in each year, beginning in 1980 and ending in 2018. While there are year-to-year variations, we also see a large upward trend. According to this data, the number of extremes has risen from about 200 a year in 1980 to about 800 in 2018.

These catastrophes are not caused by weather alone. A humanitarian disaster – of course - always involves humans, and these weather-related catastrophes arise through the complex interplay of human exposure, vulnerability, natural variability, and human-induced climate change. Still, this time series should really get your attention, especially if you think of any children with affection. These children face an increasingly dangerous adulthood. According to Munich Re, these extremes are accompanied by billions in losses (about $755 billion [€680 billion]) between 2015 and 2018.Footnote 6

While both news reporters and climate scientists have been very interested in these recent extremes, there has been little in the popular literature addressing these events in an accessible way. That is what we are doing here. This book examines extremes over the 2015–2019 time period, cataloging their severity, and explaining how climate change may have contributed to their intensity or magnitude. The 2015–2019 time period was chosen because this period has been exceptionally “disastrous,” and is also recent enough to still resonate with our personal experience. This work focuses on categories of extremes with substantial immediate human impacts (droughts, floods, fires). My goal is to help you both understand and experience how climate change is contributing to more frequent and intense extreme events.

As we will explore in detail, climate change is already impacting us. Relevant recent examples, which we will explore in this book, include the unprecedented 2017 hurricane season; the 2017 California wildfire season; extreme global temperatures in 2015–2019; the gigantic 2015/16 El Niño event; the sequence of repetitive droughts striking East Africa in 2016, 2017, and 2018; severe flooding in Houston and Bangladesh; coral bleaching in the Great Barrier Reef; and the increase in wildfire frequency and extent in the western United States and Australia. These events have had catastrophic impacts. In 2017, ten Atlantic hurricanes arose in rapid succession: Franklin, Gert, Harvey, Irma, Jose, Katia, Lee, Maria, Nate, and Ophelia.Footnote 7 In August 2017, Hurricane Harvey dropped heavier and more widespread rainfall than any other U.S. tropical cyclone on record - more than 60 inches or 152 cm in at least two locations (p. 6 of resulting in approximately $85 billion in estimated damages according to Munich Re. In September 2017, Hurricane Irma reached Category 5 on the Saffir–Simpson scale with sustained winds of over 185 miles per hour – for more than 37 hours – longer and stronger than any hurricane on record.Footnote 8 Then Maria, another Category 5 storm, devastated Puerto Rico, causing almost 3,000 deaths and leaving millions without power for months on end.

In California, where I live, wildfires ravaged 4.5 million acres between 2015 and 2018, an area almost as big as the state of New Jersey. In 2018, the official cost figures for the Camp and Woolsey fires were $9 billion and $2 billion dollars, respectively, with estimates for all wildfire losses ranging from $15 billion to $19 billion.Footnote 9 Estimates for 2017 hover around $18 billion.Footnote 10 According to 2017Footnote 11 and 2018Footnote 12 reports from the risk management/reinsurance company Aon, the global economic cost of natural disasters in 2017 and 2018 totaled $653 billion, the costliest back-to-back years for weather disasters on record. Public and private insurers paid out over $237 billion in 2017 and 2018. In 2019–2020, a staggering and globally unprecedented 21 percent of Australia’s forested area burned,Footnote 13 as climate change contributed to extreme temperatures and dry conditions.Footnote 14 Ecologists estimate that a billion or more animals (mammals, birds, and reptiles) may have perished in these conflagrations.

In 2017, hurricanes Harvey, Maria, and Irma produced some $240 billion in damages. Flooding and Typhoon Hato in China resulted in $15.5 billion in losses. Extreme precipitation and a landslide in Sierra Leone led to the catastrophic death of 1,441 people. Droughts in East Africa pushed some 13 million people into severe food insecurity: these millions of people faced a very real threat of famine.Footnote 15 The 2017 drought in southern Europe led to some $7 billion in economic losses. In 2018, Hurricanes Michael and Florence battered the United States, while typhoons Jebi and Mangkhut and Tropical Storm Rumbia pummeled China and Japan, with total losses estimated at around $66.4 billion. During July 2018, torrential rains in Japan resulted in almost $10 billion in damages. These natural disasters, combined with the impact of an earthquake, threatened to push Japan into recession. In August 2018, in the Indian state of Kerala, a multibillion-dollar flood led to more than 480 deaths.Footnote 16 In Europe, in the summer of 2018, unprecedented wildfires spread as far north as Sweden, and drought-related economic losses were around $9 billion in northern and central Europe. Government and industry are beginning to pay attention.

While humans have always faced the perils of natural disasters, these data suggest that the human and economic cost of climate and weather extremes is increasing quickly as our population and economies expand and our planet rapidly warms. Understanding the link between extremes and warming is both a moral and an existential imperative. If global warming is increasing the intensity of extremes, then we are all harming people now – drought-affected people like Eregae Lokeno Nakali in Africa, or the nearly 3,000 Puerto Ricans who perished due to Hurricane Maria, the 88 people who died in the Camp Fire in California or the billion animals who perished during Australia’s Black Summer.

These increasing perils also pose an existential threat. Already the magnitude of these losses is already sufficient to rattle some of the largest global economies. In poor and moderate-income countries, the toll of the climate crises helps retard economic progress and enforce vicious cycles of poverty. Extreme events can and do contribute to human migration and refugee crises. Understanding the role of climate change can improve our crisis preparation and powers of prediction. If we think global warming is increasing the intensity or frequency of a certain type of disaster, then we can better prepare for these events. As we will see later, this preparation often involves a “follow the energy” principle – in other words, we should look for where climate change is creating predictable disturbances to the climate system by essentially ‘turning up the volume’ of natural variations. Good examples of this are recent improvements to the United States’ hurricane forecasting capabilities, or the successful drought forecasts made for East Africa in 2016 and 2017.Footnote 17 By learning more about the interaction of climate change and climate extremes, we can face the future better prepared and better informed. One goal of this book is to describe how energy moves through the Earth’s energy system, so you can both better appreciate the beauty of our life-sustaining complex planet, and how human-induced warming is altering this system in dangerous and alarming ways.

Extreme Event Attribution and Prediction

This book draws in an informal way from the new science of extreme event attribution. This new science seeks to rigorously identify the “fingerprint” of climate change within weather and climate extremes.Footnote 18 Like Sherlock Holmes or an epidemiologist, attribution scientists examine the causes of dangerous events, asking questions like “when Eregae and Aita suffered severe droughts in 2016 and 2017, were these droughts made more intense or more probable due to climate change? Or when the region flooded the following year (in the spring of 2018), was that event made more probable due to climate change?” “Climate attribution” is the accessible process of assigning causal explanations. I work in this research field because it improves my ability to provide effective support for humanitarian relief agencies. I started as a drought detective, trying to understand why rains sometimes fail in Africa. This led to my involvement with climate attribution research. My motivation is humanitarian. If global warming is making an extreme event more common, then we should prepare.

Experts describe (footnote 18) that there is a range in our ability to understand and attribute the role played by climate change in climate extremes (Figure 1.4). At one end of the spectrum, the role that warming plays in heat waves is pretty obvious. As the Earth gets warmer, heat waves get more frequent, warmer, and more extensive in space and time.

Figure 1.4 Extreme event attribution schema. The top row lists the “usual suspects” discussed in the National Academy of Sciences report on climate extreme attribution (footnote 18). The bottom row lists underestimated hazards examined by the author: El Niño and La Niña, which will be discussed in Chapters 810.

Ironically, perhaps, both very dry and very wet conditions (droughts and extreme rainfall events) are the next easiest to understand and attribute. We can be almost certain that global warming is going to make both droughts and extreme rainfall events more common and intense. Why the certainty? Because the same basic physical relationship underlies both tendencies. We can be sure the atmosphere will get warmer. Warmer air can hold more water. The fact that warmer air can hold more water will make droughts drier and extreme rainfall events wetter and more frequent.

Think of the atmosphere as a sponge that grows bigger as the atmosphere warms. When the atmosphere warms, the individual molecules bounce around more, moving farther apart. This produces more room for gaseous water vapor molecules to squeeze in between. This makes it easier for water molecules to move from plant leaves into the atmosphere – a process called transpiration. It also makes it easier for water to evaporate from bare soil. So when conditions are dry and the atmosphere warms, this bigger atmospheric sponge can draw more water from the land. This increases the intensity of droughts. Conversely, when the atmosphere is humid, this bigger sponge will hold more water. Even though we can’t see this invisible water vapor, it can be rapidly caught up in storms, lifted, cooled, and sent hurtling down to earth as precipitation. So warmer air leads to more intense rainfall. Another important aspect of these precipitation processes is that atmospheric water vapor moves around with the winds. An individual water molecule may be swept into the atmosphere from a distant ocean, travel thousands of miles, and then converge with H20 molecules from a totally different part of the ocean, helping fuel extreme rainfall events like hurricanes.

Climate extremes like El Niño and La Niña fall within the intermediate range in our ability to understand and attribute (Figure 1.4). This is where much of my research has been focused, because these “climate events” evolve much more slowly than “weather events” – which means that we can sometimes predict their impacts many months in advance, helping prevent famines.

When El Niño events occur, sea surface temperatures get exceptionally warm in the eastern tropical Pacific. This exceptional persistent warmth can trigger droughts in dozens of countries, some of which (like Ethiopia and Zimbabwe) are very poor and very food insecure. Very recent research, some of it mine, has shown that climate change is making the eastern Pacific sea surface temperature warmer during El Niños. These warmer ocean conditions can trigger more intense droughts in Africa, Asia, Indonesia, and Central/South America. El Niño’s sister, La Niña, often follows a strong El Niño event. Ocean conditions in the eastern Pacific cool while temperatures in the western Pacific become very warm. These exceptionally warm west Pacific conditions can trigger severe droughts in places like Kenya and the western United States. Understanding these relationships can lead to important forecasts. For example, in late 2016 we predicted the spring 2017 drought that struck Kenya, Somalia, and southern Ethiopia. This prediction helped motivate early and effective humanitarian responses, helping save the lives and livelihoods of thousands of people. These types of climate extremes begin very simply; we know that the oceans are getting substantially warmer. It then gets more complicated when we analyze how these warming ocean conditions can trigger extreme droughts and precipitation over land.

At the most difficult end of the spectrum, it can be very hard to attribute the role that climate change may play in individual wildfire or hurricane events. Humans frequently start wildfires, and once started, wildfires are driven by very complicated interactions between vegetation and highly local weather and winds – which can themselves be driven by wildfires. Hurricanes and cyclones are also rapidly evolving, complicated, nonlinear, chaotic disturbances. Climate scientists have more difficulty modeling these events and their changes. But as we will see, there does appear to be solid observational data linking global warming to more dangerous fires and more devastating hurricanes, cyclones, and typhoons.

Book Structure and Intent

Between 2015 and 2019, climate and weather extremes placed millions of people in harm’s way while causing hundreds of billions of dollars in damages. Climate change is making weather extremes more frequent and intense. This book provides an accessible entry point for nonspecialists who want to know how and why. Recognizing how climate change is exacerbating expensive and dangerous weather and climate extremes, now, should help us understand why we need to immediately curb our rampant greenhouse gas emissions. But understanding why climate change is happening so rapidly may be just as important. Our atmosphere is very thin. Yet our rapid growth in global prosperity is unnecessarily predicated on burning fossil fuels, which threatens the very basis of our fragile life support system. To understand how greenhouse gasses are messing with our planet, it helps to appreciate how awesome the Earth–Sun system is. We absorb solar radiation and turn it into growing complexity. This is our Earth’s “fragile flame,” a miraculous negentropic order-inducing life support system that we are really messing up.

Addressing the question of how, Chapters 24 provide a sometimes lighthearted introduction to climate change and climate science. These chapters seek to explain how our Earth–Sun system works, how unique and beautiful it is, and why it is so fragile. We live on a “Goldilocks Planet” where a cascade of energetic balances create excellent conditions for the evolution and sustenance of life. But this life support system depends on a very thin atmosphere and the maintenance of temperatures within a narrow range in which water can take on liquid, frozen, and gaseous states.

Chapters 512 then focus on 2015–2019 extreme heat waves (Chapter 5); precipitation extremes (Chapter 6); hurricanes, typhoons, and cyclones (Chapter 7); El Niños and La Niñas (Chapters 810); and droughts and wildfires (Chapters 11 and 12). While we can’t examine every event, what we find, and summarize in Table 1.1, is that the aggregate impact of these extreme events is massive, from both a humanitarian and an economic perspective. Climate change is already increasing the intensity and frequency of extremes, contributing to dangerous, expensive, and disastrous climate-related crises. While we hear about these crises in the news, treating them in aggregate in this book underscores the grave collective nature of this growing peril.

Table 1.1. Notable extremes and impacts examined in this book.

Ch. 5 Temperature Extremes
  • Between 2015 and 2019, 59 extreme-temperature disasters, related to 8,800 deaths, 65,592 injuries, affecting 4.4 million people, and resulting in $1.8 billion in losses.

  • Exceptional warmth, over more than 20% of the Earth’s surface, has become the new norm.

  • These exceptional temperatures threaten the Earth’s basic ecosystem services: fisheries, coral reefs, and carbon dioxide-absorbing rainforests.

  • Without reductions in emissions, global temperature extremes may increase by more than +5°C (9°F).

  • An analysis of daily global temperature data indicates massive (~15 billion people-days) increases in observed extreme heat exposure events.

  • The 2050 climate change projections indicate further increases of about 60 to 75 billion people-days.

Ch. 6 Precipitation Extremes
  • As air temperatures increase, the atmosphere can hold more water, leading to increases in the intensity of the most extreme precipitation events.

  • Rainfall observations indicate that global precipitation extremes have already increased by more than 8%.

  • Between 1998 and 2017, floods, storms, and hurricanes affected more people than any other type of disaster, impacting 2.7 billion people overall and resulting in $1.99 trillion of recorded economic losses.a

  • The 2015–2019 disaster data suggests that the most dangerous non-cyclone storms affected 223 million people, led to more than 9,000 deaths, and resulted in $80 billion in damages.

Ch. 7 Hurricanes, Cyclones, and Typhoons
  • According to NOAA data, in 2015–2019, extreme hurricanes, cyclones, and typhoons caused $315 billion in damages in the United States.

  • Between 2000 and 2019, these extremes caused $746 billion in damages in the U.S.

  • In 2017, Hurricane Harvey dropped more than 50 inches of rainfall in a few days on the Houston area causing $125 billion dollars in damage.

  • In 2017, Hurricane Maria devastated Puerto Rico. The NOAA-estimated price tag was approximately $90 billion dollars. Deaths: estimated at about 3,000 people.

Ch. 8 Conceptual Models of Climate Change and Prediction
  • The amount of energy in the upper ocean is increasing very rapidly. Between 1960 and 1990, the total energy increased by about 3×1022 Joules. Between 1990 and 2019, heat content increased by more than five times this amount.

  • Between 2014 and 2019, the global upper ocean heat energy increase was equivalent to the energy released by about 12 million one-megaton nuclear bombs.

  • This heat moves around in the oceans, interacting with natural variability to produce potentially catastrophic climate disruptions – and opportunities for prediction.

  • In October–November 2019, extremely warm western Indian Ocean sea surface temperatures contributed to extreme flooding and locusts in East Africa and drought in southern Africa and Australia.

Ch. 9 Climate Change Made the 2015–2016 El Niño More Extreme
  • The 2015–2016 El Niño was associated with extreme drought and air temperatures in Ethiopia, Southern Africa, India, Southeast Asia, Oceania, and Brazil.

  • These dry arid conditions triggered widespread crop failures, pushing more than 35 million people into food insecurity.

  • Climate change made the 2015–2016 El Niño about +0.8°C warmer, making terrestrial droughts more intense.

  • Climate change models predict that more extreme El Niños are likely over the next 20 years.

Ch. 10 Bigger La Niñas and the East African Climate Paradox
  • The 2015–2016 El Niño was followed by La Niña conditions, characterized by cool East Pacific sea surface temperatures; but climate change is intensifying the severity of La Niña impacts in some areas by dramatically warming the Western Pacific.

  • In late 2016 and early 2017, East Africa suffered from back-to-back droughts that pushed millions of people into near-famine conditions.

  • Climate change enhanced the severity of these droughts by increasing Western Pacific sea surface temperatures.

  • This long-term warming of the Western Pacific may explain the East African Climate Paradox.

Ch. 11 Fire and Drought in the Western US
  • In the United States, annual wildfire extent observations exhibit a strong upward trend, with average fire sizes tripling between the early 1980s and late 2010s.

  • These increases in wildfire extent are tightly coupled with increases in aridity, which are related to both increases in air temperatures and upper-level atmospheric ridging.

  • The 2017 and 2018 US wildfires have caused more than $40 billion in damages, and more than a hundred fatalities.

Ch. 12 Fire and Drought in Australia
  • In late 2019, half of Australia’s Kangaroo Island burned, killing more than 17,000 koalas, and more than a third of the island’s kangaroos.

  • In 2019–2020, a staggering and globally unprecedented 21% of Australia’s forested area burned.

  • During this “Black Summer,” fires stretched over 186,000 square kilometers (72,000 square miles), destroying over 5,900 buildings (including 2,779 homes) and killing at least 34 people.

  • Exceptionally warm conditions and climate change enhanced the intensity of the Australian drought and associated fires.

  • Expert assessments indicate that a billion or more animals (mammals, birds, and reptiles) perished in these conflagrations.

a United Nations report, Economic losses, poverty & disasters: 1998-2017,

Unfortunately, as we will see in Chapter 13, our current emissions put us on track for calamitous warming. But rising greenhouse gas emissions can also be seen as symptomatic of beneficial growth. Chapter 14 highlights our growing capacity to discover, communicate, and create. Education, technology, and rapid economic growth have lifted billions from poverty. Our ability to image and observe the world has expanded tremendously, and we can afford to do the right thing. Between 1961 and 2050, we will carry out humanity’s greatest experiment in parallel processing, as billions of individuals grow, think, discover, and consume. We are living in the midst of a potentially positive time bomb. The years between 1961 and 2050 will contain as many person-years as 8000–1500 BCE, 1501 BCE–1000 AD, or 1001–1959 AD. Never have so many seen so much, known so much, or done so much – or had such a profound capacity to affect the world for good or ill. We can avoid a global climate catastrophe.Footnote 19 But we need to believe in science, believe in each other, and do what is right. This book serves these goals by contributing to a broader understanding of climate extremes in a rapidly warming world.


a United Nations report, Economic losses, poverty & disasters: 1998-2017,

2 Funk C., Concerns about the Kenya/Somalia short rains,

October 19, 2016,

4 Kenya Food Security and Nutrition Working Group, “Short Rains Food And Nutrition Security Assessment Findings,” Kenya Food Security Meeting, March 8, 2019.

6 Throughout this book loss estimates will be provided in inflation-adjusted “real” values.



13 Boer, Matthias M., Víctor Resco de Dios, and Ross A. Bradstock. “Unprecedented burn area of Australian mega forest fires.” Nature Climate Change (2020): 1–

14 van Oldenborgh, G. J., Krikken, F., Lewis, S., Leach, N. J., Lehner, F., Saunders, K. R., van Weele, M., Haustein, K., Li, S., Wallom, D., Sparrow, S., Arrighi, J., Singh, R. P., van Aalst, M. K., Philip, S. Y., Vautard, R., and Otto, F. E. L.: Attribution of the Australian bushfire risk to anthropogenic climate change, Natural Hazards and Earth System Sciences Discussion,, in review, 2020.

15 Funk, Chris, et al.Examining the role of unusually warm Indo-Pacific sea-surface temperatures in recent African droughts.” Quarterly Journal of the Royal Meteorological Society 144 (2018):

18 National Academies of Sciences, Engineering, and Medicine. “Attribution of extreme weather events in the context of climate change.” National Academies Press, 2016.

19 Hoegh-Guldberg, Ove, et al. “Impacts of 1.5 C global warming on natural and human systems.” Global Warming of 1.5° C.: An IPCC Special Report. IPCC Secretariat, 2018. 175–311.

Figure 0

Figure 1.1 Eregae Lokeno Nakali. Photograph by Mathilde Berg Utzon.

Figure 1

Figure 1.2 Eregae’s young daughter Aita Eregae Nakali.

Photograph by Mathilde Berg Utzon
Figure 2

Figure 1.3 The number of extreme events for each year, based on the Munich Re reinsurance company’s Natural Catastrophe database.

Figure 3

Figure 1.4 Extreme event attribution schema. The top row lists the “usual suspects” discussed in the National Academy of Sciences report on climate extreme attribution (footnote 18). The bottom row lists underestimated hazards examined by the author: El Niño and La Niña, which will be discussed in Chapters 8–10.

Figure 4

Table 1.1. Notable extremes and impacts examined in this book.

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Available formats