Highlights from Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming by Paul Hawken

100 highlighted passages, references are to the Kindle version, Last annotated on May 30, 2017

Outsize subsidies make fossil fuels look less expensive, obscuring wind power’s cost competitiveness, and they give fossil fuels an incumbent advantage, making investment more attractive. 477

Ongoing cost reduction will soon make wind energy the least expensive source of installed electricity capacity, perhaps within a decade. Current costs are 2.9 cents per kilowatt-hour for wind, 3.8 cents per kilowatt-hour for natural gas combined-cycle plants, and 5.7 cents per kllowatt-hour for utility-scale solar. A Goldman Sachs research paper published in June 2016 stated simply, “wind provides the lowest cost source of new capacity.” The cost of both wind and solar includes production tax credits; however, Goldman Sachs believes that the continuing decline in wind turbine costs will make up for the phasing out of tax credits in 2023. Wind projects built in 2016 are coming in at 2.3 cents per kilowatt-hour. A Morgan Stanley analysis shows that new wind energy production in the Midwest is one-third of the cost of natural gas combined-cycle plants. And finally, Bloomberg New Energy Finance has calculated that “the lifetime cost of wind and solar is less than the cost of building new fossil fuel plants.” 479

Bloomberg predicts that wind energy will be the lowest-cost energy globally by 2030. (This accounting does not include the cost of fossil fuels with respect to air quality, health, pollution, damage to the environment, and global warming.) Costs are going down because turbines are being built at higher elevations—meaning longer blades in locations that have more wind, a combination that has more than doubled the capacity of a given turbine to generate electricity. Onshore turbines can be made larger because assembly is far easier than on water. Turbines that generate 20 megawatts of power with tip heights taller than the Empire State Building are on the drawing boards. 485

Could the United States power itself with wind? The National Renewable Energy Laboratory calculates that nearly 775,000 square miles of land area is suited to 40 to 50 percent capacity factors, more than twice the average capacity factor a decade ago. (A wind turbine is rated to be able to produce a stated amount of power at a constant given wind speed, however the capacity factor takes into consideration the variability of wind speed in the actual location.) The ways and means for the United States to be fossil fuel and energy independent are here. 491

Coal is a freeloader when it comes to the costs borne by society for environmental impacts. Putting aside the difference in emissions costs—none for wind, high for fossil fuels—the subsidy arguments do not include the difference in water usage between wind and fossil fuels. Wind power uses 98 to 99 percent less water than fossil fuel–generated electricity. Coal, gas, and nuclear power require massive amounts of water for cooling, withdrawing more water than agriculture—22 trillion to 62 trillion gallons per year. Water for many fossil fuel and nuclear plants is “free,” bestowed by the federal government or the states, but it is hardly free and instead represents another unacknowledged subsidy. Who else besides the fossil fuel and nuclear power industries can take trillions of gallons of water in the United States and not pay for it? 496

not keep up with demand. Wind energy, like other sources of energy, is part of a system. Investment in energy storage, transmission infrastructure, and distributed generation is essential to its growth. Technologies and infrastructure to store excess power are developing quickly now. Power lines to connect remote wind farms to areas of high demand are being built. For the world, the decision is simple: Invest in the future or in the past. • 509

A microgrid is a localized grouping of distributed energy sources, like solar, wind, in-stream hydro, and biomass, together with energy storage or backup generation and load management tools. This system can operate as a stand-alone entity or its users can plug into the larger grid as needed. Microgrids are nimble, efficient microcosms of the big grid, designed for smaller, diverse energy sources. By bringing together renewables and storage, microgrids provide reliable power that can augment the centralized model or operate independently in an emergency situation. 526

The use of local supply to serve local demand reduces energy lost in transmission and distribution, increasing efficiency of delivery compared to a centralized grid. When coal is burned to boil water to turn a turbine to generate electricity, two-thirds of the energy is dispersed as waste heat and in-line losses. Microgrid installations in grid-connected regions offer several key advantages. Civilization is dependent on electricity; losing access due to outages or blackouts is a critical risk. In developed countries, economic losses from such events can be many billions of dollars per year. Associated social costs include increased crime, transportation failures, and food wastage, in addition to the environmental cost of diesel-fueled backup power. Studies indicate that as overall demand for electricity increases, owing in part to use of air conditioning and electric vehicles, existing power systems become more frail and blackouts more frequent. By virtue of being localized systems, microgrids are more resilient and can be more responsive to local demand. In the event of disruption, a microgrid can focus on critical loads that require uninterrupted service, such as hospitals, and shed noncritical loads until adequate supply is restored. 531

Globally, 1.1 billion people do not have access to a grid or electricity. More than 95 percent of them live in sub-Saharan Africa and Asia, a majority in rural areas where highly polluting kerosene lamps are still the main source of lighting and meals are cooked on rudimentary stoves. While the connection between electrification and human development has been clear, progress has remained slow due to the high cost of extending the grid to remote regions. In rural parts of Asia and Africa, populations are best supplied with electricity from microgrids (and in remote locations 540

This is the Solar Settlement in Freiburg, Germany. A 59-home community, it is the first in the world to have a positive energy balance, with each home producing $5,600 per year in solar energy profits. The way to positive energy is designing homes that are extraordinarily energy efficient, what designer Rolf Disch calls PlusEnergy. 546

In many places, the business models of large utilities are not compatible with distributed energy and storage. They have sunk costs in a system of generation and delivery that is becoming outmoded. Where utilities are resistant, monopoly, not technology, is the biggest challenge for microgrids. Lessons could cross-pollinate: large grids need to be less rigid and adapt to a changing world; microgrids need to adopt robust technical standards for long-term success. 550

Hot water and steam within hydrothermal reservoirs can be piped to the surface and drive turbines to produce electricity—a 572

Conventionally, locating hydrothermal pools is the first step; however, pinpointing subsurface resources has been a challenge and limitation for geothermal power. It is difficult to know where reservoirs are and expensive to drill wells to find out. But new exploration techniques are opening up larger territories. 580

Geothermal is reliable, efficient, and the heat source itself is free. In the process of pursuing its potential, geothermal’s negatives need to be managed. Whether naturally occurring or pumped in, water and steam can be laced with dissolved gases, including carbon dioxide, and toxic substances such as mercury, arsenic, and boric acid. Though its emissions per megawatt hour are just 5 to 10 percent of a coal plant’s, geothermal is not without greenhouse impact. In addition, depleting hydrothermal pools can cause soil subsidence, while hydrofracturing can produce microearthquakes. Additional concerns include land-use change that can cause noise pollution, foul smells, and impacts on viewsheds. In twenty-four countries 601

around the world, tackling these drawbacks is proving worthwhile because geothermal power can provide reliable, abundant, and affordable electricity, with low operational costs over its lifetime. In El Salvador and the Philippines, geothermal accounts for a quarter of national electric capacity. In volcanic Iceland, it is one-third. In Kenya, thanks to the activity beneath Africa’s Great Rift Valley, fully half of the country’s electricity generation is geothermal—and growing. Though less than .5 percent of national electricity production, U.S. geothermal plants lead the world with 3.7 gigawatts of installed capacity. 607

According to the Geothermal Energy Association, 39 countries could supply 100 percent of their electricity needs from geothermal energy, yet only 6 to 7 percent of the world’s potential geothermal power has been tapped. 612

The up-front costs of drilling are especially steep, particularly in less certain, more complex environments. That is why public investment, national targets for its production, and agreements that guarantee power will be purchased from companies that develop it have a crucial role to play in expansion. These measures all help to rein in the level of risk for investing. While hot new technologies such as enhanced geothermal systems advance, continued development of traditional geothermal generation remains indispensable, especially in Indonesia, Central America, and East Africa—places where the planet is most active and “earth heat” is abundant. • 617

IMPACT: Our calculations assume geothermal grows from .66 percent of global electricity generation to 4.9 percent by 2050. That growth could reduce emissions by 16.6 gigatons of carbon dioxide and save $1 trillion in energy costs over thirty years and $2.1 trillion over the lifetime of the infrastructure. By providing baseload electricity, geothermal also supports expansion of variable renewables. 622

Any scenario for reversing global warming includes a massive ramp-up of solar power by mid-century. It simply makes sense; the sun shines every day, providing a virtually unlimited, clean, and free fuel at a price that never changes. 633

solar farms operate at a utility scale, more like conventional power plants in the amount of electricity they produce, but dramatically different in their emissions. When their entire life cycle is taken into account, solar farms curtail 94 percent of the carbon emissions that coal plants emit and completely eliminate emissions of sulfur and nitrous oxides, mercury, and particulates. Beyond the ecosystem damage those pollutants do, they are major contributors to outdoor air pollution, responsible for 3.7 million premature deaths in 2012. 637

The first solar PV farms went up in the early 1980s. Now, these utility-scale installations account for 65 percent of additions to solar PV capacity around the world. They can be found in deserts, on military bases, atop closed landfills, and even floating on reservoirs, where they perform the additional benefit of reducing evaporation. If Ukrainian officials have their way, Chernobyl, the site of a mass nuclear meltdown in 1986, will house a 1-gigawatt solar farm, which would be one of the world’s largest. Whatever the site, farm is an appropriate term for these expansive solar arrays because photovoltaics are literally a means of energy harvesting. The silicon panels that make up a solar farm harvest the photons streaming to earth from the sun. Inside a panel’s hermetically sealed environment, photons energize electrons and create electrical current—from light to voltage, precisely as the name suggests. Beyond particles, no moving parts are required. 646

Silicon PV technology was discovered by accident in the 1950s, alongside the invention of the silicon transistor that is present in almost every electronic device used today. That work happened under the auspices of the United States’ Bell Labs, accelerated by a search for sources of distributed power that could work in hot, humid, remote locations, where batteries might fail and the grid would not reach. Silicon, the Bell scientists found, was a major improvement over the selenium that had been standard for experimental solar panels since the late 1800s. It achieved more than a tenfold rise in efficiency of converting light to electricity. In the 1954 debut of the Bell “solar battery,” a tiny panel of silicon cells powered a twenty-one-inch Ferris wheel and then a radio transmitter. Small as they were, the demos duly impressed the press. The New York Times proclaimed it might mark “the beginning of a new era, leading eventually to the realization of one of mankind’s most cherished dreams—the harnessing of the almost limitless energy of the sun for the uses of civilization.” 653

Ironically, the first major purchaser of solar cells for use on earth was the oil industry, which needed a distributed energy source for its rigs and extraction operations. 662

today. The decline in price has always outpaced predictions, and drops will continue. Informed predictions about the cost and growth of solar PV indicate that it will soon become the least expensive energy in the world. It is already the fastest growing. Solar power is a solution, but it might be fair to say it is a revolution as well. Constructing a solar farm is also getting cheaper, and it is faster than creating a new coal, natural gas, or nuclear plant. In many parts of the world, solar PV is now cost competitive with or less costly than conventional power generation. Developers are bidding select projects at pennies per kilowatt-hour, which would have been unthinkable a few years ago. Thanks to plunging hard and soft costs, alongside zero fuel use and modest maintenance requirements over time, the growth of large-scale solar has outpaced the most bullish expectations. Compared to rooftop solar, solar farms enjoy lower installation costs per watt, and their efficacy in translating sunlight into electricity (known as efficiency rating) is higher. When their panels rotate to make the most of the sun’s rays, generation can improve by 40 percent or more. At the same time, no matter where solar panels are placed, they are subject to the diurnal and variable nature of solar radiation and its misalignment with electricity use, peaking midday while demand peaks a few hours later. That is why as solar generation continues to grow, so should complementary renewables that are constant, such as geothermal, and that have rhythms different from the sun, such as wind, which tends to pick up at night. Energy storage and more flexible, intelligent grids that can manage the variability of production from PV farms will also be integral to solar’s success. 665

they’re less than 2 percent of the global electricity mix at present. Could solar meet 20 percent of global energy needs by 2027, as some University of Oxford researchers calculate? 678

In 2015, solar PV met almost 8 percent of electricity demand in Italy and more than 6 percent in Germany and Greece, leaders in the solar revolution. PV has had a long history of surpassing expectations and taking unexpected leaps forward. 682

The year was 1884, when the first solar array appeared on a rooftop in New York City. Experimentalist Charles Fritts installed it after discovering that a thin layer of selenium on a metal plate could produce a current of electricity when exposed to light. 696

Though the scientific establishment of Fritts’s day believed power generation depended on heat, Fritts was convinced that “photoelectric” modules would wind up competing with coal-fired power plants. 700

The first such plant had been brought online by Thomas Edison just two years earlier, also in New York City. 701

the mysterious waves and particles of the sun’s light continuously strike the surface of the planet with an energy more than ten thousand times the world’s total use. Small-scale photovoltaic systems, typically sited on rooftops, are playing a significant role in harnessing that light, the most abundant resource on earth. When photons strike the thin wafers of silicon crystal within a vacuum-sealed solar panel, they knock electrons loose and produce an electrical circuit. These subatomic particles are the only moving parts in a solar panel, which requires no fuel. While solar photovoltaics (PV) provide less than 2 percent of the world’s electricity at present, PV has seen exponential growth over the past decade. In 2015 distributed systems of less than 100 kilowatts accounted for roughly 30 percent of solar PV capacity installed worldwide. In Germany, one of the world’s solar leaders, the majority of photovoltaic capacity is on rooftops, which don 1.5 million systems. In Bangladesh, population 157 million, more than 3.6 million home solar systems have been installed. Fully 16 percent of Australian homes have them. Transforming a square meter of rooftop into a miniature power station is proving irresistible. 705

The soft costs of financing, acquisition, permitting, and installation can be half the cost of a rooftop system and have not seen the same dip as panels themselves. That is part of the reason rooftop solar is more expensive than its utility-scale kin. Nonetheless, small-scale PV already generates electricity more cheaply than it can be brought from the grid in some parts of the United States, in many small island states, and in countries including Australia, Denmark, Germany, Italy, and Spain. 724

When placed on a grid-connected roof, they produce energy at the site of consumption, avoiding the inevitable losses of grid transmission. They can help utilities meet broader demand by feeding unused electricity into the grid, especially in summer, when solar is humming and electricity needs run high. 729

This “net metering” arrangement, selling excess electricity back to the grid, can make solar panels financially feasible for homeowners, offsetting the electricity they buy at night or when the sun is not shining. Numerous studies show that the financial benefit of rooftop PV runs both ways. By having it as part of an energy-generation portfolio, utilities can avoid the capital costs of additional coal or gas plants, for which their customers would otherwise have to pay, and broader society is spared the environmental and public health impacts. Added PV supply at times of highest electricity demand can also curb the use of expensive and polluting peak generators. 731

For all involved, the need for a grid “commons” continues, 738

The first solar array installed by Charles Fritts in 1884 in New York City. Fritts built the first solar panels in 1881, reporting that the current was “continuous, constant and of considerable force not only by exposure to sunlight but also to dim, diffused daylight, and even to lamplight.” 742

In Bangladesh alone, those 3.6 million home solar systems have generated 115,000 direct jobs and 50,000 more downstream. Since the late nineteenth century, human beings in many places have relied on centralized plants that burn fossil fuels and send electricity out to a system of cables, towers, and poles. As households adopt rooftop solar (increasingly accompanied and enabled by distributed energy storage), they transform generation and its ownership, shifting away from utility monopolies and making power production their own. As electric vehicles also spread, “gassing up” can be done at home, supplanting oil companies. With producer and user as one, energy gets democratized. Charles Fritts had this vision in the 1880s, as he looked out over the roofscape of New York City. Today, that vision is increasingly coming to fruition. 748

Our analysis assumes rooftop solar PV can grow from .4 percent of electricity generation globally to 7 percent by 2050. That growth can avoid 24.6 gigatons of emissions. We assume an implementation cost of $1,883 per kilowatt, dropping to $627 per kilowatt by 2050. Over three decades, the technology could save $3.4 trillion in home energy costs. 755

Proponents believe wave power could provide up to 25 percent of U.S. electricity and 30 percent or more in Australia. In Scotland, that number may be upwards of 70 percent. Wave and tidal energy is currently the most expensive of all renewables, and with the price of wind and solar dropping rapidly, that gap will likely widen. However, as this technology evolves and policy comes into place to support implementation, marine renewables may follow a similar path, attracting private capital investment and the interest of large companies such as General Electric and Siemens. On a trajectory like that, wave and tidal energy could also become cost competitive with fossil fuels. 804

CSP plants rely on immense amounts of direct sunshine—direct normal irradiance (DNI). DNI is highest in hot, dry regions where skies are clear, typically between latitudes of 15 and 40 degrees. Optimal locales range from the Middle East to Mexico, Chile to Western China, India to Australia. According to a 2014 study in the journal Nature Climate Change, the Mediterranean basin and the Kalahari Desert of Southern Africa have the greatest potential for large, interconnected networks of CSP, with the potential to supply power at a cost comparable to that of fossil fuels. In many regions best suited to making solar thermal power, technical generation capacity (the electricity they could be capable of producing) far surpasses demand. With advances in transmission lines, they could supply local populations and export power to places where CSP is more constrained. 829

molten salt can be kept hot for five to ten hours, depending on the DNI of a particular site, then used to generate electricity when the sun’s rays soften. That capacity is crucial for the hours when people remain awake, consuming electricity, but the sun has gone down. Even without molten salt, CSP plants can store heat for shorter periods of time, giving them the ability to buffer variations in irradiance, as can happen on cloudy days—something PV panels cannot do. 841

renewables, CSP is easier to integrate into the conventional grid and can be a powerful complement to solar PV. Some plants pair the two technologies, strengthening the value of both. 845

Compared to wind and PV generation, the major downside of CSP, to date, is that it is less efficient, in terms of both energy and economics. Solar thermal plants convert a smaller percentage of the sun’s energy to electricity than PV panels do, and they are highly capital intensive, particularly because of the mirrors used. Experts anticipate that the reliability of CSP will hasten its growth, however, and as the technology scales, costs could fall quickly. Efficiency of energy conversion is also projected to improve. (Technologies currently under development are already proving it.) 853

The use of heat often implies the use of water for cooling, which can be a scarce resource in the hot, dry places ideal for CSP. Dry cooling is possible, but it is less efficient and more expensive. Lastly, by concentrating channels of intense heat, CSP plants have killed bats and birds, which literally combust in midair. One company, Solar Reserve, has developed an effective strategy to stop bird deaths; spreading that practice for mirror operation will be critical as more plants come online. 859

In the near-term, substituting biomass for fossil fuels can prevent carbon stocks in the atmosphere from rising. Photosynthesis is an energy conversion and storage process; solar energy is captured and stored as carbohydrates in biomass. Under the right conditions and over millions of years, biomass left intact would become coal, oil, or natural gas—the carbon-dense fossil fuels that, 883

There is an if: Biomass energy is a viable solution if it uses appropriate feedstock, such as waste products or sustainably grown, appropriate energy crops. Optimally, it also uses a low-emission conversion technology such as gasification or digestion. Using annual grain crops such as corn and sorghum for energy production depletes groundwater, causes erosion, and requires high inputs of energy in the form of fertilizer and equipment operation. The sustainable alternative is perennial crops or so-called short-rotation woody crops. Perennial herbaceous grasses such as switchgrass and Miscanthus can be harvested for five to ten years before replanting becomes necessary, and they require fewer inputs of water, and labor. Woody crops such as shrub willow, eucalyptus, and poplar are able to grow on “marginal” land not suited to food production. Because they grow back after being cut close to the ground, they can be harvested repeatedly for ten to twenty years. These woody crops circumvent the deforestation that comes with using forests as fuel and sequester carbon more rapidly than most other trees can, but not if they replace already forested lands. Care needs to be taken with both Miscanthus and eucalyptus, however, as they are invasive.                  This is a single-pass, cut-and-chip harvester reaping fast-growing willow for a carbon-neutral biomass plant, part of Germany’s Energiewende or “energy turnaround.” Germany currently produces over 30 percent of its energy from wood, but when the total cost of harvesting and processing wood is calculated, it is not carbon neutral. The industry exists because of significant government subsidies. 892

Another important feedstock is waste from wood and agricultural processing. Scraps from saw mills and paper mills are valuable biomass. So are discarded stalks, husks, leaves, and cobs from crops grown for food or animal feed. While it is important to leave crop residues on fields to promote soil health, a portion of those agricultural wastes can be diverted for biomass energy production. Many such organic residues would either decompose on-site or get burned in slash piles, thus releasing their stored carbon regardless (albeit perhaps over longer periods of time). When organic matter decomposes, it often releases methane and when it is burned in piles, it releases black carbon (soot). Both methane and soot increase global warming faster than carbon dioxide; simply preventing them from being emitted can yield a significant benefit, beyond putting the embodied energy of biomass to productive use. 908

In the states of Washington, Vermont, Massachusetts, Wisconsin, and New York, the amount of slash generated by logging operations falls far short of the amount needed to feed the proposed biomass burners. In Ohio and North Carolina, utilities have been more forthright and admit that biomass electricity generation means cutting and burning trees. The trees will grow back, but over decades—a lengthy and uncertain lag time to achieve carbon neutrality. 916

At present, biomass fuels 2 percent of global electricity production, more than any other renewable. In some countries—Sweden, Finland, and Latvia among them—bioenergy is 20 to 30 percent of the national generation mix, almost entirely provided for by trees. Biomass energy is on the rise in China, India, Japan, South Korea, and Brazil. Reaching greater scale in more places requires investment in biomass production facilities and infrastructure for collection, transport, and storage. 926

extracting invasive species from forests accompanied with appropriate ecological safeguards can be a good source of biomass energy. That approach is being tested in India by the government of the state of Sikkim, which is making “bio-briquettes” for clean cookstoves. Additionally, smallholder farmers need to be protected from displacement by industrial-scale approaches to biomass generation. Most important to bear in mind is that biomass—carefully regulated and managed—is a bridge to reach a clean energy future, not the destination itself. • 930

Currently, nuclear power generates about 11 percent of the world’s electricity and contributes about 4.8 percent to the world’s total energy supply. There are 444 operating nuclear reactors in 29 countries, and 63 more are under construction. Of the 29 countries with operative nuclear power plants, France has the highest nuclear contribution to its electrical energy supply, at 76 percent. Nuclear reactors are broadly classified by generation. The oldest, Generation 1, first came online in the 1950s and are now almost entirely decommissioned. The majority of current nuclear capacity falls into the Generation 2 category. (Chernobyl consisted of both Gen 1 and Gen 2. The four Fukushima Daiichi reactors are Gen 2, as are all of the reactors in the United States and France.) Generation 2 distinguishes itself from its predecessor by the use of water (as opposed to graphite) to slow down nuclear chain reactions and the use of enriched, as opposed to natural, uranium for fuel. The Generation 3 reactors, five of which are in operation worldwide and several more under construction, along with Generation 4 reactors, which are currently being researched, constitute what is called “advanced nuclear.” In theory, advanced nuclear has standardized designs that reduce construction time and achieve longer operating lifetimes, improved safety features, greater 955

According to physicist Amory Lovins, “Nuclear power is the only energy source where mishap or malice can destroy so much value or kill many faraway people; the only one whose materials, technologies, and skills can help make and hide nuclear weapons; the only proposed climate solution that [creates] proliferation, major accidents, and radioactive-waste dangers. . . . [N]uclear power is continuing its decades-long collapse in the global marketplace because it’s grossly uncompetitive, unneeded, and obsolete—so hopelessly uneconomic that one need not debate whether it is clean and safe; it weakens electric reliability and national security; and it worsens climate change compared with devoting the same money and time to more effective options.” 980

new reactor designs that address some of the main criticisms and concerns about nuclear energy. These reactors are being designed to shut down quickly and safely with no one in attendance (“walk-away safety”). They employ better coolants and can scale down to plants one five-hundredth the size of conventional nuclear. They reduce construction time to one or two years. The world may soon have better choices when it comes to nuclear energy than it has had in the past, but it may be too late given the accelerating cost and construction advantages of renewable energy technologies. 1015

U.S. coal-fired or nuclear power plants are about 34 percent efficient in terms of producing electricity, which means two-thirds of the energy goes up the flue and heats the sky. All told, the U.S. power-generation sector throws away an amount of heat equivalent to the entire energy budget of Japan. Put your hand behind the tailpipe of your car when the engine is running. It is the same principle, only worse—75 to 80 percent of the energy generated by an internal combustion engine is wasted heat. Coal and single-cycle gas generating plants are the best candidates for capturing wasted energy through cogeneration. Cogeneration puts otherwise-forfeited energy to work, heating and cooling homes and offices or creating additional electricity. Cogeneration systems, also known as combined heat and power (CHP), capture excess heat generated during electricity production and use that thermal energy at or near the site for district heating and other purposes. The opportunity to reduce emissions and save money through cogeneration is significant because of the inherent low efficiency of electrical generation. 1038

In the United States, 87 percent of them are used in energy-intensive industries such as chemical, paper, and metal manufacturing and food processing. In countries such as Denmark and Finland, cogeneration makes up a significant part of electricity production largely because of its use in district heating systems. In countries with a high-CHP share in total generation, such as Denmark and Finland, the need to address energy security played a decisive role. 1047

the cold climate in the country has provided a basis for a healthy return on investment in heat supply infrastructure. As of 2013, 69 percent of Finland’s district heating is provided by cogeneration systems. Denmark’s approach to energy supply is policy driven. Although the use of CHP in the country dates back to 1903, it was the 1970s oil crisis that spurred the use of this technology. Since that time, policies have compelled local authorities to identify opportunities for energy-efficient heat production, helped to move power generation from centralized plants to a decentralized network, and incentivized the use of cogeneration generally, and renewable-based systems particularly, through tax policy. 1052

From a financial viewpoint, the adoption of cogeneration systems makes sense for many industrial and commercial uses, as well as for some residential uses. Cogeneration makes it possible for users that do not have access to renewable energy to produce more energy with the same amount, and cost, of fuel. In addition to clear financial benefits, adoption will reduce greenhouse gas emissions to the extent cogeneration reduces reliance on fossil fuels for heating and electricity. Moreover, it will play a substantial role in the ushering in of smart, distributed, and renewable-based energy networks. Because distributed systems are necessarily placed close to the site of generation, they reduce the need for transmission lines. Cogeneration systems are easily adaptable to user preference and thus allow for a variety of energy sources. Additionally, cogeneration systems can help to reduce water usage and thermal water pollution when compared to separate combustion-based heat and power systems, decreasing demand pressure on another vital natural resource. • 1065

they are often installed with a diesel generator to supply electricity when the breeze does not blow. From a carbon perspective, relying on a fossil fuel complement is not ideal. There are already some combined solar photovoltaic and micro wind systems on the market, which is one fruitful alternative. Improved battery storage technology could also boost the viability of small-scale wind. Where these turbines are linked up to the grid, owners may be able to send their unneeded electrons out to the larger network for financial return through net metering. Experts estimate that a million or more micro wind turbines are currently in use around the world, with the majority whirling in China, the United States, and the United Kingdom. 1101

This is a VisionAIR5 vertical axis wind turbine that is quieter than a human whisper at low speeds. The turbine is 10.5 feet high and is rated at 3.2 kilowatts of power. The minimum wind speed required is 9 miles per hour and it can withstand speeds up to 110 miles per hour. Integrating micro turbines into large structures within the built environment is showing unique promise. 1113

Human-induced climate change was first identified in 1800 and again in 1831 by the same scientist, Alexander von Humboldt. 1124

During his five-year immersion in largely unspoiled wilderness, Humboldt realized that nature is intricately interconnected in ways that surpass human knowledge. And he saw that living systems, and indeed the whole of the planet, are highly vulnerable to disturbances by human beings. The principles of the web of life variously described by Darwin, Muir, Emerson, and Thoreau arose directly from Humboldt’s Latin America expedition and his subsequent writings. 1138

When he listed the three ways in which the human species was affecting the climate, he named deforestation, ruthless irrigation, and, perhaps most prophetically, the “great masses of steam and gas” produced in the industrial centers. No one but Humboldt had looked at the relationship between humankind and nature like this before. • 1169

“No, sir, no air is more combustible than the air from marshy soil,” Volta wrote on November 21, 1776, beginning to fathom the connection between the gas and decaying vegetation. 1190

methane gases as they decompose. 1197

In Portland, Oregon, 3.5-foot-wide turbines fit perfectly inside underground pipes. As water rushes down from the Cascade Range to the city, it also generates power for the local utility—without harming flow. This subcategory of in-stream technologies is called conduit hydropower. According to a national assessment of U.S. hydrokinetic resources, the in-stream energy that is technically recoverable is more than 100 terawatt-hours per year. Roughly 95 percent of it is located in the Mississippi, Alaska, Pacific Northwest, Ohio, and Missouri hydrologic regions. The technology needed to seize that opportunity is fairly new and rare, likened by some to the status of wind power fifteen years ago. Small players populate the industry, but their efforts benefit from the similarities between in-stream and tidal energy and the surge of research and investment in the latter. 1253

IMPACT: If in-stream hydro grows to supply 1.7 percent of the world’s electricity by 2050, it can reduce 4 gigatons of carbon dioxide emissions and save $1.8 trillion in energy costs. Communities in remote mountainous areas are among the last regions in need of electrification; in-stream hydro offers them a reliable and economical method of generating electricity. 1268

One study conducted in the 1980s of a New Jersey incinerator showed the following results: If 2,250 tons of trash were incinerated daily, the annual emissions would be 5 tons of lead, 17 tons of mercury, 580 pounds of cadmium, 2,248 tons of nitrous oxide, 853 tons of sulfur dioxide, 777 tons of hydrogen chloride, 87 tons of sulfuric acid, 18 tons of fluorides, and 98 tons of particulate matter small enough to lodge permanently in the lungs. The study also showed varying amounts of the persistent toxic pollutant dioxin, depending on the amount of paper and wood involved in incineration. Essentially, inert hazardous waste goes into an incinerator and bioavailable hazardous and toxic emissions come out. Modern incinerators address these concerns in part. Employing considerably higher temperatures and equipped with scrubbers and filters, almost all traces of pollutants can be captured—but not all. For cities and urban communities, the allure of waste-to-energy plants is compelling. In Europe, more than 450 waste-to-energy plants exist, burning 25 percent of all waste. Sweden leads the field, importing 800,000 tons of garbage from other countries, at considerable cost in carbon emissions, to fuel its district heating plants—the most extensive network in the world. The Swedes assert that they are very careful about the trash they import: It has to be well sorted with all of the recyclables, including food, removed. Landfills are banned, so if it is not recycled, it is burned. 1301

Swedish municipal association believes that for every ton of garbage, imported or domestic, there is an equivalent savings of 1,100 pounds of carbon dioxide if compared to the garbage being landfilled. As a strategy for managing our trash, waste-to-energy is better than the landfill alternative when state-of-the-art facilities are employed. In Europe, despite the market for trash (the Germans, Danes, Dutch, and Belgians also are in the business of importing garbage), the rate of recycling, including green waste, is going up, and a 50 percent recycling mandate is in place for the year 2050. 1315

Waste-to-energy continues to evoke strong feelings. Its champions point to the land spared from dumps and to a cleaner-burning source of power. One ton of waste can generate as much electricity as one-third of a ton of coal. But opponents continue to decry pollution, however trace, as well as high capital costs and potential for perverse effects on recycling or composting. Because incineration is often cheaper than those alternatives, it can win out with municipalities when it comes to cost. Data shows high recycling rates tend to go hand in hand with high rates of waste-to-energy use, but some argue recycling could be higher in the absence of burning trash. These are among the reasons that construction of new plants in the United States has been at a near standstill for many years, despite evolution in incineration technology. 1321

ten large corporations have committed to zero waste to landfill, including Interface, Subaru, Toyota, and Google. 1340

Zero waste is a growing movement that wants to go upstream, not down, in order to change the nature of waste and the ways in which society recaptures its value. It is saying, in essence, that material flows in society can imitate what we see in forests and grasslands where there truly is no waste that is not feedstock for some other form of life. It relies on green chemistry and material innovation that has the end in mind, not just the beginning. Like solar and wind energy, technologies that were once impractical and unaffordable, zero waste is an engineering and design revolution, which will make waste so valuable that the last thing you would want to do is burn or bury it. 1342

One way to overcome surplus is through high voltage direct current (HVDC) power lines that can extend energy for thousands of miles with small line losses. Additionally, there are a suite of energy-storage technologies that address precisely these issues. How does a utility store large 1423

Nevada is experimenting with energy storage by rail. Here, where there is no water, gravity can still be enlisted. The system takes its cues from the myth of Sisyphus, forever pushing his boulder up a hill. When power is abundant, mining railcars freighted with 230 tons of rock and cement are sent up to a rail yard three thousand feet higher. The railcars are equipped with 2-megawatt generators that act as an engine on the way up. On the way down, a regenerative braking system converts rolling resistance to electrical power. The technology at the core of both solutions is more than a century old. When the railcars are parked at elevation, they can sit there for a year and not lose any power, while reservoirs evaporate. Both systems share a key advantage: how quickly they can respond to demand. The ramp-up time to full power is seconds, whereas fossil fuel plants take minutes or hours. The grid needs storage at speed. 1442

In 2012, the global consultancy McKinsey & Company predicted $200-per-kilowatt-hour batteries by 2020, but both General Motors and Tesla achieved that in 2016. 1490

At current cost, a $500 billion investment in distributed energy systems would save U.S. businesses and households $4 trillion in peak-demand utility billing over the next thirty years. Battery cost could halve in the next four years, further amplifying those gains. If storage is used to enable more reliance on renewables there will be substantial climate benefits. If storage is just used to shift peak demand to nights in systems that rely heavily on coal, there will be little benefit. Not so long ago, solar photovoltaics had high carbon costs. So much coal-fired energy was required for the glass, aluminum, gases, installation, and 3,600-degree Fahrenheit sintering ovens, it would have been fair to call solar panels coal extenders. Today, the energy costs of making solar have dropped significantly. Batteries seem to be following suit; plummeting costs will likely be accompanied by less energy-intensive manufacturing methods. As that occurs, an entirely new energy grid will come online—one that promises to be more resilient and democratic—powered by sensors, apps, and software yet to be invented. IMPACT: Distributed energy storage is an essential supporting technology for many solutions. Microgrids, net zero buildings, grid flexibility, and rooftop solar all depend on or are amplified by the use of dispersed storage systems, which facilitate uptake of renewable energy and avert the expansion of coal, oil, and gas electricity generation. Adoption of distributed storage varies 1491

Hot water for showers, laundry, and washing dishes consumes a quarter of residential energy use worldwide; in commercial buildings, that number is roughly 12 percent. SWH can reduce that fuel consumption by 50 to 70 percent. But it has yet to be widely tapped as a resource because of up-front costs and complexity of installation, which are higher than gas and electric boilers. Increasingly, SWH gets considered alongside solar photovoltaics, when it comes to roof space, investment, and potential synergies or trade-offs between the two. To achieve uptake at the level Cyprus and Israel have accomplished, governments can require or incent use in new construction—and more and more they are. If the United States maximized its potential for SWH, the country could reduce natural gas consumption by 2.5 percent and electricity use by 1 percent, and avoid producing 57 million tons of carbon each year—as much as 13 coal-fired power plants or 9.9 million cars. With national ambitions for growth in Malawi, Morocco, Mozambique, Jordan, Italy, Thailand, and beyond, clearly SWH has not come close to reaching its zenith, even 125 years after the original Climax was first devised. 1536

Livestock emissions, including carbon dioxide, nitrous oxide, and methane, are responsible for an estimated 18 to 20 percent of greenhouse gases annually, a source second only to fossil fuels. If you add to livestock all other food-related emissions—from farming to deforestation to food waste—what we eat turns out to be the number one cause of global warming. This section profiles techniques, behaviors, 1554

On average, adults require 50 grams of protein each day, but in 2009, the average per capita consumption was 68 grams per day—36 percent higher than necessary. In the 1582

a 2016 World Resources Institute report analyzes a variety of possible dietary modifications and finds that “ambitious animal protein reduction”—focused on reducing overconsumption of animal-based foods in regions where people devour more than 60 grams of protein and 2,500 calories per day—holds the greatest promise for ensuring a sustainable future for global food supply and the planet. “In a world that is on a course to demand more than 70 percent more food, nearly 80 percent more animal-based foods, and 95 percent more beef between 2006 and 2050,” its authors argue, altering meat consumption patterns is critical to achieving a host of global goals related to hunger, healthy lives, water management, terrestrial ecosystems, and, of course, climate change. 1595

Beyond promoting “reducetarianism,” if not vegetarianism, it is also necessary to reframe meat as a delicacy, rather than a staple. First and foremost, that means ending price-distorting government subsidies, such as those benefiting the U.S. livestock industry, so that the wholesale and resale prices of animal protein more accurately reflect their true cost. In 2013, $53 billion went to livestock subsidies in the thirty-five countries affiliated with the Organisation for Economic Co-operation and Development alone. Some experts are proposing a more pointed intervention: levying a tax on meat—similar to taxes on cigarettes—to reflect its social and environmental externalities and dissuade purchases. Financial disincentives, government targets for reducing the amount of beef consumed, and campaigns that liken meat eating to tobacco use—in tandem with shifting social norms around meat consumption and healthy diets—may effectively conspire to make meat less desirable. 1617

Eating with a lighter footprint reduces emissions, of course, but also tends to be healthier, leading to lower rates of chronic disease. 1629

Plant-based diets also open opportunities to preserve land that might otherwise go into livestock production and to engage current agricultural land in other, carbon-sequestering uses. 1632

A comprehensive study out of Stanford University estimates that there are 950 million to 1.1 billion acres of deserted farmland around the world—acreage once used for crops or pasture that has not been restored as forest or converted to development. Ninety-nine percent of that abandonment occurred in the past century. 1656

According to Professor Rattan Lal of the Ohio State University, the world’s cultivated soils have lost 50 to 70 percent of their original carbon stock, which combines with oxygen in the air to become carbon dioxide. 1663

Passive approaches require little money but lots of time. Active restoration is often labor intensive, yet necessary for cultivation to revive. Its costs are higher, but so is its speed to productivity, carbon storage, and ecosystem services. 1667

suppression and marginalization along gender lines actually hurt everyone, while equity is good for all. 2788

On average, women make up 43 percent of the agricultural labor force and produce 60 to 80 percent of food crops in poorer parts of the world. Often unpaid or low-paid laborers, they cultivate field and tree crops, tend livestock, and grow home gardens. Most of them are part of the 475 million smallholder families who operate on less than 5 acres of land—to some extent for their own subsistence—and are among the world’s poorest and most undernourished people. Their stories are diverse but share a key commonality: compared with their male counterparts, women have less access to a range of resources, from land and credit to education and technology. Even though they farm as capably and efficiently as men, inequality in assets, inputs, and support means women produce less on the same amount of land. Closing this gender gap can improve the lives of women, their families and communities, while addressing global warming. 2800

According to the Food and Agriculture Organization of the United Nations (FAO), if all women smallholders receive equal access to productive resources, their farm yields will rise by 20 to 30 percent, total agricultural output in low-income countries will increase by 2.5 to 4 percent, and the number of undernourished people in the world will drop by 12 to 17 percent. One hundred million to 150 million people will no longer be hungry. A few studies demonstrate that if women have access to the same resources as men—all else being equal—their outputs actually surpass parity: They exceed men’s by 7 to 23 percent. Closing this gender gap can also control emissions. When agricultural plots produce well, there is less pressure to deforest for additional ground, and where regenerative practices replace chemical-intensive ones, soil becomes a carbon storehouse. Land rights are at the center of the gender gap that women smallholders face. Few countries break down statistics of landownership along the lines of gender, but those that do reveal an underlying inequity: Just 10 to 20 percent of landholders are women, and within that group, insecure land rights are a persistent challenge. Many women are legally prevented from owning or inheriting property in their own right, limiting their decision making and leaving them vulnerable to displacement. In the words of Kindati Lakshmi, of India’s Mahabubnagar district, “Owning a piece of land only would enable us to live with dignity and without hunger. We have no other way except to continue our struggle until we get land.” 2806

Layered onto that reality, women have less access to cash and credit. Lack of capital can mean lack of fertilizer, farm tools, water, and seeds. Their second-class status restricts technical information and support from extension agents, membership in rural cooperatives, and marketing and sales outlets. As more men migrate to cities seeking nonfarm income, women are increasingly central to cultivation in low-income countries. They are hindered, however, from making decisions about and investments in improving the land they farm. Their responsibility grows but their rights and resources may not. 2818

Proven interventions address ways in which current systems fail women, though complexity on the ground defies one-size-fits-all strategies. Bina Agarwal, a professor at the University of Manchester and the author of A Field of One’s Own, captures the range of measures needed: Recognize and affirm women as farmers rather than farm helpers—a perception that undermines them from the start. Increase women’s access to land and secure clear, independent tenure—not mediated through and controlled by men. Improve women’s access to the training and resources they lack, provided with their specific needs in mind—microcredit in particular. Focus research and development on crops women cultivate and farming systems they use. Foster institutional innovation and collective approaches designed for women smallholders, such as group farming efforts. Agarwal’s last tenet is powerful. When women take part in cooperatives for growing, learning, financing, and selling, they achieve economies of scale in their operations and pool their influence, know-how, and talent. They also are able to share labor, resources, and risk, such as the uncertain outcomes of trying a new crop or farming technique. Innovation and farm productivity follow. These outcomes are all the more important in a world shifting under global warming, to which farmers must readily adapt. 2822

As with all smallholder farmers, diversity in cultivation helps annual yields to be more resilient and successful over time. For decades, agribusiness and government agencies have promoted techniques that are dependent on synthetic fertilizers, pesticides, and genetically modified seeds, which have left many smallholders at risk of market-commodity collapse, pest infestations, and deteriorated soil. In contrast, diversifying crops through practices such as agroforestry and intercropping does not require the same or, in many cases, any chemical inputs and creates more-resilient landscapes. Women—and men—need support not just in achieving yield gains but in yields gained sustainably, in ways that support them in the face of climate change. According to the FAO, “It will be difficult, if not impossible, to eradicate global poverty and end hunger without building resilience to climate change in smallholder agriculture through the widespread adoption of sustainable . . . practices.” As the world’s population continues to grow—reaching a projected 9.7 billion by 2050—agricultural production will need to rise (in tandem with reduced food waste and dietary shifts). Given constraints on arable land and the need to protect intact forests, humanity will need to increase the yield of each plot. Growing more food on the same amount of land cannot be done without attending to smallholders, so many of whom are women, whose farming needs have been much overlooked. Countries that have higher levels of gender equality have higher average cereal yields; high levels of inequality correlate with the opposite outcome. If women smallholders get equal rights to land and resources, they will grow more food, feed their families better throughout the year, and gain more household income. 2834

When women earn more, they reinvest 90 percent of the money they make into education, health, and nutrition for their families and communities, compared to 30 to 40 percent for men. In Nepal, for example, strengthening women’s landownership has a direct link to better health outcomes for children. With this solution, human well-being and climate are tightly linked, and what is good for equity is good for the livelihoods of all genders. • IMPACT: This solution models reduced emissions from avoided deforestation, resulting from increasing the yield of women smallholders. Based on literature in the field, we assume yield per plot can rise by 26 percent, if women’s access to finance and resources comes closer to parity with men’s. If women managing 98 million acres receive equal assistance and achieve that 26 percent gain, this solution could reduce 2.1 gigatons of carbon dioxide by 2050. 2847

when family planning focuses on healthcare provision and meeting women’s expressed needs, empowerment, equality, and well-being are the goal; benefits to the planet are side effects. Challenges to expanding access to family planning range from basic supply of affordable and culturally appropriate contraception to education about sex and reproduction; from faraway health centers to hostile attitudes of medical providers; from social and religious norms to sexual partners’ opposition to using birth control. Currently, the world faces a $5.3 billion funding shortfall for providing the access to reproductive healthcare that women say they want to have. The success stories in family planning, however, are striking. Iran put a program into place in the early 1990s that has been touted as among the most successful such efforts in history. Completely voluntary, it involved religious leaders, educated the public, and provided free access to contraception. As a result, fertility rates halved in just one decade. In Bangladesh, average birth rates fell from six children in the 1980s to two now, as the door-to-door approach pioneered at the Matlab hospital spread across the country: female health workers providing basic care for women and children where they live. These and other success stories show that provision of contraception is rarely sufficient. Family planning requires social reinforcement, for example the radio and television soap operas now used in many places to shift perceptions of what is “normal” or “right.” After 2885

To revere human life it is necessary to ensure a viable, vibrant home for all. Honoring the dignity of women and children through family planning is not about centralized governments forcing the birth rate down—or up, through natalist policies. Nor is it about agencies or activists in rich countries, where emissions are highest, telling people elsewhere to stop having children. It is most essentially about freedom and opportunity for women and the recognition of basic human rights. Currently, family planning programs receive just 1 percent of all overseas development assistance. That number could double, with low-income countries aiming to match it—a moral move that happens to have meaning for the planet. • IMPACT: Increased adoption of reproductive healthcare and family planning is an essential component to achieve the United Nations’ 2015 medium global population projection of 9.7 billion people by 2050. If investment in family planning, particularly in low-income countries, does not materialize, the world’s population could come closer to the high projection, adding another 1 billion people to the planet. We model the impact of this solution based on the difference in how much energy, building space, food, waste, and transportation would be used in a world with little to no investment in family planning, compared to one in which the projection of 9.7 billion is realized. The resulting emissions reductions could be 123.0 gigatons of carbon dioxide, at an average annual cost of $10.77 per user in low-income countries. Because educating girls has an important impact on the use of family planning, we allocate 50 percent of the total potential emissions reductions to each solution—59.6 gigatons a piece. 2903

Kenya has made significant gains in education, with more than 80 percent of all boys and girls currently enrolled in primary schools. In secondary schools, the rate of enrollment drops to 50 percent for both boys and girls. Poverty is the main cause of low overall enrollment, and given socioeconomic norms, boys receive priority for higher education when there are financial constraints. Girls’ education, it turns out, has a dramatic bearing on global warming. Women with more years of education have fewer, healthier children and actively manage their reproductive health. In 2011, the journal Science published a demographic analysis of the impact of girls’ education on population growth. It details a “fast track” scenario, based on South Korea’s actual climb from one of the least to most educated countries in the world. If all nations adopted a similar rate and achieved 100 percent enrollment of girls in primary and secondary school, by 2050 there would be 843 million fewer people worldwide than if current enrollment rates sustain. According to the Brookings Institution, “The difference between a woman with no years of schooling and with 12 years of schooling is almost four to five children per woman. And it is precisely in those areas of the world where girls are having the hardest time getting educated that population growth is the fastest.” 2924

In the poorest countries, per capita greenhouse gas emissions are low. People do not have enough energy to properly sanitize their water, read or study at night, or power their small businesses. There are 1.1 billion people who do not have any electricity at all. From one-tenth of a ton of carbon dioxide per person in Madagascar to 1.8 tons in India, per-capita emissions in lower-income countries are a fraction of the U.S. rate of 18 tons per person per year. Nevertheless, changes in fertility rates in these countries would have multiple benefits on virtually every level of global society. Nobel laureate and girls’ education activist Malala Yousafzai has famously said, “One child, one teacher, one book, and one pen, can change the world.” An enormous body of evidence supports her conviction: For starters, educated girls realize higher wages and greater upward mobility, contributing to economic growth. Their rates of maternal mortality drop, as do mortality rates of their babies. They are less likely to marry as children or against their will. They have lower incidence of HIV/AIDS and malaria—the “social vaccine” effect. Their agricultural plots are more productive and their families better nourished. They are more empowered at home, at work, and in society. An intrinsic right, education lays a foundation for vibrant lives for girls and women, their families, and their 2934

communities. It is the most powerful lever available for breaking the cycle of intergenerational poverty, while mitigating emissions by curbing population growth. A 2010 economic study shows that investment in educating girls is “highly cost-competitive with almost all of the existing options for carbon emissions abatement”—perhaps just $10 per ton of carbon dioxide. Education also shores up resilience in terms of climate change impacts—something the world needs as warming mounts. Across low-income countries, there is a strong link between women and the natural systems at the heart of family and community life. Women often and increasingly play roles as stewards and managers of food, soil, trees, and water. As educated girls become educated women, they can fuse inherited traditional knowledge with new information accessed through the written word. As cycles of change play out in the times to come—new diseases blighting fruit trees, soil composition shifting in garden plots, altered seed-sowing times—educated women can marshal multiple ways of knowing to observe, understand, reevaluate, and take action to sustain themselves and those who depend on them. 2944

A 2013 study found that educating girls “is the single most important social and economic factor associated with a reduction in vulnerability to natural disasters.” The single most important. It is a conclusion drawn from examining the experiences of 125 countries since 1980 and echoes other analyses. Educated girls and women have a better capacity to cope with shocks from natural disasters and extreme weather events and are therefore less likely to be injured, displaced, or killed when one strikes. This decreased vulnerability also extends to their children, families, and the elderly. In the past twenty-five years, the global community has learned a great deal about educating girls. So many challenges impede girls from realizing their right to education, and yet, around the world, they are striving for a place in the classroom. Economic barriers include lack of family funds for school fees and uniforms, as well as prioritizing the more immediate benefits of having girls fetch water or firewood, or work a market stall or plot of land. Cultural barriers encompass traditional beliefs that girls should tend the home rather than learn to read and write, should be married off at a young age, and, when resources are slim, should be skipped over so boys can be sent to school instead. Barriers are also safety related. Schools that are farther afield put girls at risk of gender-based violence on their way to and from, not to mention dangers and discomforts at school itself. Disability, pregnancy, childbirth, and female genital mutilation also can be obstacles. 2961

The barriers are real, but so are the solutions. The most effective approaches concurrently tackle access (school affordability, proximity, and suitability for girls) and quality (good teachers and good learning outcomes). Mobilizing communities to support and sustain progress on girls’ education is a powerful accelerant. The encyclopedic book What Works in Girls’ Education maps out seven areas of interconnected interventions: Make school affordable. For example, provide family stipends for keeping girls in school. Help girls overcome health barriers. For example, offer deworming treatments. Reduce the time and distance to get to school. For example, provide girls with bikes. Make schools more girl-friendly. For example, offer child-care programs for young mothers. Improve school quality. For example, invest in more and better teachers. Increase community engagement. For example, train community education activists. Sustain girls’ education during emergencies. For example, establish schools in refugee camps. 2973

Today, 62 million girls are denied the right to attend school. The situation is most dire in secondary classrooms. In South Asia, less than half of girls—16.3 million—are enrolled in secondary school. In sub-Saharan Africa, fewer than one in three girls attends secondary school, and while 75 percent of all girls start school, just 8 percent finish their secondary education. Currently, international aid for education projects is about $13 billion annually. Given the link between girls’ education and climate change, funds for climate mitigation and adaptation could enable the world to scale solutions rapidly. It could be a powerful match between education’s need for funds and the world’s need for proven climate solutions. Moreover, 2984

Education is grounded in the belief that every life bubbles with innate potential. When it comes to climate change, nurturing the promise of each girl can shape the future for all. • IMPACT: Two solutions influence family size and global population: educating girls and family planning. Because the exact dynamic between these solutions is impossible to determine, our models allocate 50 percent of the total potential impact to each. We assume that these impacts result from thirteen years of schooling, including primary through secondary education. According to the United Nations Educational, Scientific, and Cultural Organization, by closing an annual financing gap of $39 billion, universal education in low- and lower-middle-income countries can be achieved. It could result in 59.6 gigatons of emissions reduced by 2050. The return on that investment is incalculable. 2990