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.

Chapter 11 examines the rapid increases in wildfire extent and the role played by increased temperature-induced evaporative demand. The story begins in early November 2018, with the author clearing bone-dry brush in the woods behind his house, and discussing these incredibly dry conditions on a local radio show with his local volunteer firefighter friends. In dry regions, warmer air's increased ability to hold water increases its capacity to draw moisture from soils and plants. On November 6, the Community Alert show discussed the exceptionally dry conditions across California, and how these dry-fuel conditions were expected to combine with high winds to set the stage for potential conflagration. At sunrise on November 8, the Camp Fire, California's deadliest and costliest conflagration, broke out. Since the early 1980s, annual US wildfire extents have increased by more than 300 percent. In California, 2017 and 2018 wildfire extent, deaths, and damages were staggering. Increases in western US wildfire extent are tightly coupled with increases in aridity, which are related to both increases in air temperatures and atmospheric water demand. The 2017 and 2018 US wildfires were associated with more than $40 billion in damages and more than a hundred fatalities. Chapter 11 concludes with a firsthand account from Laura Eilerts, a ninety-one-year-old woman who lost her house in the Paradise Fire and drove herself to safety.

To explore our collective future, scientists develop plausible emission, pollution, and land use scenarios. Some of these scenarios describe rapid economic and population growth, and concomitant increases in fossil fuel emissions. Other scenarios describe a rapid transition to clean energy and increased efficiency. Data from the 2019 Global Carbon Project carbon budget indicate that 2019 emissions were very close to scientists’ most dangerous emissions pathway. Like a marble careening across the top of an inverted paper Dixie cup, these rapid emissions could lead to runaway global warming, risking a planetary plummet if temperature increases shrink ice caps, reduce the ocean and land’s ability to sequester carbon dioxide, and/or increase fire emissions. Examining national emission statistics, we see that the United States is by far the greatest per capita emitter. There is some good news, however. Global energy use intensity, the amount of carbon emissions per unit of gross domestic product, is increasing rapidly. We can make more goods and services using relatively less emissions. Solar energy is rapidly becoming more affordable. But emissions have already contributed to an exponential increase in disasters costing some $2.2 trillion over the past two decades.

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. Across the mainland, two years of very low rainfall and exceptionally warm air temperatures set the stage for a catastrophic “Black Summer.” A staggering and globally unprecedented 21 percent of Australia's forested area burned. Fires stretched over 186,000 square kilometers, destroying over 5,900 buildings and killing at least 34 people. A billion or more animals perished in these conflagrations. This chapter relates the exceptionally warm temperatures to increases in vapor pressure deficits and decrease in dead fuel moisture.High vapor pressure deficits help desiccate living and dead plants, producing conditions conducive to extensive mega-fires. The year 2019 was by far the warmest year on record, and climate change simulations suggest that about half of the observed warming was due to climate change. Temperatures as warm as those observed would have been impossible without climate change. Estimating vapor pressure deficits and dead fuel moisture loads without this human-induced warming suggests that climate change greatly enhanced the background aridity that allowed the Australian fires to spread to unprecedented extents.

From the intergalactic dance of dark energy and gravity, to the push and pull of our sun’s protonic plasma, to the ebb and flow of Earth’s winds and waves, a series of delicate balances supports life on our “Goldilocks Planet.” A nice balance of gravity's pull and dark energy's push resulted in a rich quilt of galaxies and stars, with us ending up in a comfortable Green galaxy, in a prime-mid spiral section of the Milky Way galaxy, rotating around a nice sun (not too close, not too far) gently emitting in the yellow part of the energy spectrum. A healthy quantity of atmosphere and greenhouse gasses, along with the Van Allen belts, keeps out most high-energy particles and maintains a reasonable temperature. The Hadley and Walker Circulations pitch in, creating clockwise rotating circulation cells in and over the Pacific and Atlantic oceans, transporting heat away from the equator and depositing it in poleward latitudes. These circulations bring life-giving moisture to the continents, supporting abundant life. Note, however, that the manual for Spaceship Earth does not contain a warranty. Right there on the cover, next to the red “Don't Panic” logo, is emblazoned “No Returns If Opened.”

The amount of energy in the upper ocean is increasing very rapidly. Between 2014 and 2019, the global heat energy increase was equivalent to the energy released by about 12 million one-megaton nuclear bombs. But global warming does not produce an even warming of the world’s oceans. Rather, extra energy builds up and moves around in complex ways. Understanding this fact can save lives. In the near term, this recognition can lead to successful forecasts. In the longer term, this recognition will help us reduce our emissions because we can recognize now how climate change is contributing to extreme weather and catastrophes. For example, in October and November 2019, the western Indian Ocean reached the highest levels of warmth ever observed, while the eastern Indian Ocean was anomalously cold. This combination contributed to extreme flooding and locust outbreaks in East Africa and exceptionally warm and dry conditions over southern Africa and Australia. An accurate conceptual model of climate change can create opportunities for prediction. Adopting an incorrect conception of climate change as the average of collections of climate simulations can cause us to miss these opportunities.

Here, framed in the context of a humorous story, we learn about the electromagnetic spectrum, entropy, negentropy, and available potential energy. We learn to see stars as tremendous gravity-driven concentrations of matter and energy, uniquely capable of supporting increased complexity and life on our planet. Seen from this perspective, the vast empty reaches of space allow for the formation of stars, which in turn support life. Energetically closed systems are doomed to entropic heat death, as mixing drives the system inexorably toward a boring end. But energetically open systems, like the Earth, absorb solar radiation and turn it into growing complexity on a planet hovering in a “magic” and narrow temperature range. This “negentropic” system can evolve over time. This increasing complexity arises because this incoming energy supports temperature gradients that drive weather and climate systems. Climate change adds more energy, and this extra energy can create more intense gradients, and more intense weather and climate events. Understanding this simple fact improves our ability to recognize and predict the dangerous impacts occurring now. At large scales, exceptionally warm tropical waters drive drought-inducing semi-global rainfall disruptions. At regional scales, warmer Ocean and atmosphere conditions can lead to more intense storms and hurricanes. As more energy moves through our Earth system, we are experiencing more extreme weather and climate.

Climate hazards arise through interactions of weather-related shocks, vulnerability, and exposure. The atmosphere is warming and population growth is increasing, setting the stage for potentially explosive increases in impacts. Of all weather hazards, heat waves tend to be the most immediate, and often the most deadly. Unfortunately, relatively small changes in air temperatures can lead to large increases in the frequency of extreme heat waves. This chapter uses 1880–2019 monthly and 1983–2016 daily temperature estimates to explore observed increase in extreme temperatures. Exceptional warmth, over more than 20 perent of the Earth's surface, has become the new norm. Warmer-than-ever conditions prevailed in 2015 through 2019. Over this same time period 71 extreme-temperature disasters affected 4.5 million people, resulting in 9,916 deaths, 90,014 injuries, and $1.8 billion losses. These exceptional temperatures threaten the Earth's basic ecosystem services: fisheries, coral reefs, and CO2-absorbing rainforests. Analysis based on a new very high-resolution data set identifies very large increases in the number of people exposed to very warm heat waves. Between 2000 and 2016, the number of heat wave exposure events has increased by approximately 15 billion people-days. Climate change projections for 2050 indicate further increases of ~70 billion. A sidebar describes a climate attribution study on Hyderabad, India, in 2015.

The most important mechanism of climate change can be understood by everyone: Why do greenhouse gasses have such a direct warming effect on our planet? This chapter approaches this question with a Do-It-Yourself (DIY) attitude.First, the humorous tale of Stinky, Dinxie, Bif, and Moo teaches us how the greenhouse effect really works. It's a straightforward matter of balancing energy, not a matter for belief. Also, it turns out that the atmosphere is really thin, and has a lot less actual mass than we might at first think. Then, this understanding is augmented by lots and lots of data. Multiple independent data sources hammer home convergent evidence identifying very rapid levels of observed warming. Looking at air temperatures, ocean temperatures, and global sea levels, we see extremely rapid rates of warming, rates that have increased dramatically in the last decade. 2015–2019 stand out as exceptionally warm. Global temperatures are modeled extremely well by climate models, while the observed warming doesn’t track at all with changes in incoming solar radiation, and these changes are very small energetically. We don’t need to believe in climate change; we can understand and observe it. The chapter introduction and a sidebar use the devastating Thomas Fire to set this warming in context.

Our Blue Marble's unique temperature range supports water in all its three glorious phases (solid, liquid, gas). Phase transitions between liquid water and water vapor involve tremendous amounts of energy, and this energy helps fuel hurricanes. Sweeping across warm waters, winds can gather water from a vast stretch, sometimes to catastrophic effect. For example, Hurricane Harvey pummeled Houston with 9 trillion gallons of water, releasing about 76 x 1018 Joules of energy. Harvey was joined by Mathew, Maria, Irma, Florence, Michael, Dorian, and Imelda. According to NOAA data, in 2015–2019, extreme hurricanes caused $315 billion in damages. Between 2000 and 2019, these extremes caused $746 billion in damages. Climate change attribution for cyclones is difficult, given their complexity and rarity. A summary of a recent World Meteorological Organization study introduces event “detection” and “attribution,” as well as the new “storyline” approach to event attribution. Like an autopsy, storyline attribution can indicate whether climate change was one probable cause of an extreme event. From this perspective, climate change has likely contributed to the increased frequency and intensity of exceptionally strong hurricanes. The chapter concludes by discussing two important storyline attribution studies focused on very strong Atlantic hurricanes.

The stories that we tell ourselves shape our lives, express our values, and guide our body politic. Drought, Flood, Fire has made a compelling case that climate change is hurting people now and contributing to expensive catastrophes. But there are also a lot good things going on in the world. Infant deaths are declining. More kids are going to school. We are becoming much wealthier, more productive, and inventive. Countries like Germany and states like California make it clear that we can grow economically while reducing our emissions. We can afford to be like a good cowboy and wear the White Hat. Rising greenhouse gas emissions are also symptomatic of beneficial growth. Education, technology, and rapid economic expansion have lifted billions from poverty. 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. 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. But we need to believe in science, believe in each other, and do what is right.

Linking a warming atmosphere, droughts, and more extreme precipitation is our thin, thin atmosphere. If the Earth were a basketball, the atmosphere would be 0.03-inch or 0.8-mm thick, literally whisker deep. The amount of water vapor contained in this air is strongly controlled by temperature. Warmer air holds more atmospheric water vapor, resulting in more extreme precipitation. Rainfall observations indicate that global precipitation extremes have already increased by more than 8 percent. If the observed trend continues, a similar-magnitude increase is likely over the next thirty years. This is very concerning, because extreme precipitation events are already extremely dangerous and costly. Between 1998 and 2017, floods, storms, and hurricanes affected more people than any other type of disaster, impacting 2.7 billion people overall resulting in $1.99 trillion of recorded economic losses. 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. There is solid observational and model-based evidence supporting the link between a warming atmosphere and more intense precipitation extremes, and clear evidence that these extremes are having deadly and costly impacts today.