# 11.1.1: Introduction

## Understanding the Science of Climate Change: The Basics

Module 9 focuses on how agriculture contributes to global climate and how climate change will affect global agriculture. In addition, we'll explore agricultural strategies for adapting to a changing climate. But, before we explore the connections between global climate change and food production, we want to make sure that everyone understands some of the basic science underpinning global climate change.

Have you ever thought about the difference between weather and climate? If you don't like the weather right now, what do you do? In many places, you just need to "wait five minutes"! If you don't like the climate where you live, what do you do? Move! Weather is the day-to-day fluctuation in meteorological variables including temperature, precipitation, wind, and relative humidity, whereas climate is the long-term average of those variables. If someone asked you what the climate of your hometown is like, your response might be "hot and dry" or "cold and damp". Often we describe climate by the consistent expected temperature and precipitation pattern for the geographic region. So, when we talk about climate change, we're not talking about the day-to-day weather, which can at times be quite extreme. Instead, we're talking about changes in those long-term temperature and precipitation patterns that are quite predictable. A warming climate means that the average temperature over the long-term is increasing, but there can still be cold snowy days and blizzards even!

The two videos below are excellent introductions to the science of climate change. We'll use these videos as your introduction to the basic science behind our understanding of climate change that we'll build on as we explore the connections between climate change and food production in the rest of this module. Follow instructions from your instructor for this introductory section of Module 9.

### Optional Video Climate Change: Lines of Evidence

The National Academies of Sciences Engineering and Medicine have prepared an excellent 20-minute sequence of videos, Climate Change: Lines of Evidence, that explains how scientists have arrived at the state of knowledge about current climate change and its causes. Use the worksheet linked below to summarize the story that the video tells about anthropogenic greenhouse gas emissions and the resulting changes in Earth's climate. The narrator speaks pretty quickly, so you'll want to pause the video and rewind when you need to make sure you understand what he's explaining. It's important to take the time to understand and answer the questions in the worksheet because you'll use this information in a future assignment.

### Video: What is Climate? Climate Change, Lines of Evidence: Chapter 1 (25:59)

Click for a transcript of What is Climate? Climate Change, Lines of Evidence.

If the video does not show up, please watch on the NAS website.

Another resource you can use to help answer the questions is the booklet that goes with this video: Climate Change: Evidence, Impacts, Choices. It is 40 pages, so you might not want to print it. Use it as an online reference.

Penn State geology professor, Richard Alley's, 45-minute video uses earth science to tell the story of Earth's climate history and our relationship with fossil fuels. There is no worksheet associated with this video.

### Optional Video: Earth: The Operators' Manual (53:42)

Click for a transcript of Earth: The Operators' Manual video.

RICHARD ALLEY: All across the planet, nations and cities are working to reduce their dependence on fossil fuels and promote sustainable energy options.

ANNISE PARKER: Because it's the smart thing, because it makes business sense, and it's the right thing. NARRATOR: In China, Europe, and Brazil, energy innovations are changing how we live. And in the US, every branch of the military is mobilizing to cut its carbon bootprint.

DAVID TITLEY: We really believe that the climate is changing.

RICHARD ALLEY: In this program, we'll share how we know Earth is warming and why and discover what Earth science tells us about clean, green energy opportunities. I'm Richard Alley. I'm a geologist at Penn State University. But my research has taken me around the planet, from Greenland to Antarctica. I'm fascinated by how our climate has changed dramatically and often, from times with ice everywhere to no ice anywhere on the planet. Records of past climate help us learn how our Earth operates. What has happened can happen again. And I know that sometimes, things change really fast. I'm a registered Republican, play soccer on Saturdays, and go to church on Sundays. I'm a parent and a professor. I worry about jobs for my students and my daughter's future. I've been a proud member of the UN Panel on Climate Change. And I know the risks. And I've worked for an oil company and know how much we all need energy. And the best science shows we'll be better off if we address the twin stories of climate change and energy, and that the sooner we move forward, the better. Our use of fossil fuels for energy is pushing us towards a climate unlike any seen in the history of civilization. But a growing population needs more and more clean energy. But I believe science offers us an operator's manual with answers to both of these huge challenges.

[MUSIC PLAYING] NARRATOR: "Earth-- The Operator's Manual" is made possible by NSF, the National Science Foundation, where discoveries begin.

RICHARD ALLEY: Humans need energy. We always have and always will. But how we use energy is now critical for our survival. It all began with fire. Today, it's mostly fossil fuels. Now we're closing in on 7 billion of us, and the planet's population is headed toward 10 billion. Our cities and our civilization depend on vast amounts of energy. Fossil fuels-- coal, oil, and natural gas-- provide almost 80% of the energy used worldwide. Nuclear is a little less than 5%, hydropower a little under 6%, and the other renewables-- solar, wind, and geothermal-- about 1%, but growing fast. Wood and dung make up the rest. Using energy is helping many of us live better than ever before. Yet well over 1.5 billion are lagging behind, without access to electricity or clean fuels. In recent years, Brazil has brought electricity to 10 million. But in rural Ceara, some still live off the grid-- no electricity, no running water, and no refrigerators to keep food safe. Life's essentials come from their own hard labor. Education is compulsory, but studying is a challenge when evening arrives. The only light is from kerosene lamps. They're smoky, dim, and dangerous. Someday, this mother prays, the electric grid will reach her home.

TRANSLATOR: The first thing I'll do when the electricity arrives in my house will be to say a rosary and give praise to God.

REPORTER: A continuance of the Upper Air Program will provide scientific data concerning the physics of the upper atmosphere.

RICHARD ALLEY: World War II was over, but the Cold War had begun. The US Air Force needed to understand the atmosphere for communications and to design heat-seeking missiles. At certain wavelengths, carbon dioxide and water vapor block radiation, so the new missiles couldn't see very far if they used a wavelength that CO2 absorbs. Research at the Air Force Geophysics Laboratory in Hanscom, Massachusetts produced an immense database with careful measurements of atmospheric gases. Further research by others applied and extended those discoveries, clearly showing the heat-trapping influence of CO2. The Air Force hadn't set out to study global warming. They just wanted their missiles to work. But physics is physics. The atmosphere doesn't care if you're studying it for warring or warming. Adding CO2 turns up the planet's thermostat. It works the other way as well. Remove CO2, and things cool down. These are the Southern Alps of New Zealand, and their climate history shows that the physicists really got it right. These deep, thick piles of frozen water are glaciers-- slow-moving rivers of ice sitting on land. But once, when temperatures were warmer, they were liquid water stored in the sea. We're going to follow this one, the Franz Josef, from summit to ocean to see the real world impact of changing levels of CO2. It's beautiful up here on the highest snow field, but dangers lurk beneath the surface. I've spent a lot of time on the ice. It's standard practice up here to travel in pairs, roped up for safety. The glacier is fed by something like six meters of water a year-- maybe 20 meters, 60 feet of snowfall, so really seriously high snowfall. The snow and ice spread under their own weight, and it's headed downhill at something like a kilometer a year. When ice is speeding up a lot as it flows towards the coast, it can crack and open great crevasses that give you a view into the guts of the glacier. Man, this is a big one. 10, 20, 30, meters more, 100 feet or more heading down in here. And we can see a whole lot of the structure of the glacier right here.

MAN: So what we're going to do is just sit on the edge and then walk backwards, and then I'll lower you.

MAN: Climate change, energy security, and economic stability are inextricably linked. Climate change will contribute to food and water scarcity, will increase the spread of disease, and may spur or exacerbate mass migration.

RICHARD ALLEY: Who do you suppose said that? Not a pundit, not a politician. The Pentagon. These war games at Fort Irwin, California provide realistic training to keep our soldiers safe. The purpose of the Pentagon's Quadrennial Defense Review, the QDR, is to keep the nation safe. The review covers military strategies for an uncertain world. The Pentagon has to think long-term and be ready for all contingencies. The 2010 QDR was the first time that those contingencies included climate change. Rear Admiral David Titley is oceanographer of the Navy and contributed to the Defense Review.

DAVID TITLEY: Well, I think the QDR really talks about climate change in terms that really isn't for debate. And you take a look at the global temperatures. You take a look at sea level rise. You take a look at what the glaciers are doing-- not just one or two glaciers, but really glaciers worldwide. And you add all of those up together, and that's one of the reasons we really believe that the climate is changing. So the observations tell us that. Physics tells us this as well.

RICHARD ALLEY: What climate change means for key global hotspots is less clear.

DAVID TITLEY: We understand the Earth is getting warmer. We understand the oceans are getting warmer. What we do not understand is exactly how that will affect things like strong storms, rainfall rates, rainfall distribution. So yes, climate change is a certainty, but what is it going to be like in specific regions of the world, and when?

RICHARD ALLEY: One area of particular concern to the Navy is sea level rise.

DAVID TITLEY: Sea level rise is going to be a long-term and very, very significant issue for the 21st century.

RICHARD ALLEY: The QDR included an infrastructure vulnerability assessment that found that 153 Naval installations are at significant risk from climatic stresses. From Pearl Harbor, Hawaii to Norfolk, Virginia, the bases and their nearby communities will have to adapt.

DAVID TITLEY: Even with one to two meters of sea level rise, which is very, very substantial, we have time. This is not a crisis, but it is certainly going to be a strategic challenge.

RICHARD ALLEY: Globally, climate change is expected to mean more fires, floods, and famine. Nations may be destabilized. For the Pentagon, climate change is a threat multiplier. But with sound climate science, Titley believes forewarned is forearmed.

DAVID TITLEY: The good thing is the science is advanced enough in oceanography, glaciology, meteorology that we have some skill at some frames of predicting this. And if we choose to use those projections, we can, in fact, by our behavior, alter the future in our favor. RICHARD ALLEY: Titley and the Pentagon think the facts are in.

DAVID TITLEY: Climate change is happening, and there is very, very strong evidence that a large part of this is, in fact, man-made.

RICHARD ALLEY: The military is America's single largest user of energy, and it recognizes that its use of fossil fuels has to change. The Pentagon uses 300,000 barrels of oil each day. That's more than 12 million gallons. An armored Humvee gets four miles to the gallon. At full speed, an Abrams battle tank uses four gallons to the mile. And it can cost as much as $400 a gallon to get gas to some remote bases in Afghanistan. Fort Irwin is a test bed to see if the Army can operate just as effectively while using less fossil fuel and more renewables. And it's not just Fort Irwin in the Army. At Camp Pendleton, Marines were trained on an energy-saving experimental forward operating base that deployed with them to Afghanistan. ROBERT HEDELUND: Before any equipment goes into theater, we want Marines to get trained on it. So what are some of the things that we can take hold of right away and make sure that we can make a difference for the warfighter down range? RICHARD ALLEY: They test out different kinds of portable solar power units. They also practice how to purify stagnant water and make it drinkable. The Army and Marines both want to minimize the number of convoys trucking in fuel and water. A report for the Army found that in five years, more than 3,000 service members had been killed or wounded in supply convoys. ROBERT HEDELUND: And if you've got Marines guarding that convoy, and God forbid, it get hit by an IED, then what are the wounded, what are the deaths involved in that? And are we really utilizing those Marines and that capability the way we should? RICHARD ALLEY: Generators used to keep accommodations livable and computers running are also major gas guzzlers. ADORJAN FERENCZY: Right now, what we're doing is putting up a power shade. It has flexible solar panels on the top and gives us enough power to run small electronics, such as lighting systems and laptop computers. It also provides shade over the tent structure. Experimenting with this equipment in Africa proved that it could reduce the internal temperature of the tent seven to 10 degrees. RICHARD ALLEY: All the LED lights in the entire tent use just 91 watts, less than one single old-fashioned incandescent bulb. ADORJAN FERENCZY: It's a no-brainer when it comes to efficiency. RICHARD ALLEY: Light-emitting diodes don't weigh much, but they're still rugged enough to survive a typical Marine's gentle touch. ZACH LYMAN: When we put something into a military application and they beat it up, it's ruggedized. It's ready for the worst that the world can take. And so one thing that people say is if the military has used this thing and they trust it, then maybe it's OK for my backyard. RICHARD ALLEY: Renewable energy will also play an important role at sea and in the air. The Navy's Makin Island is an amphibious assault ship with jump jets, helicopters, and landing craft. It's the first vessel to have both gas turbines and a hybrid electric drive, which it can use for 75% of its time at sea. This Prius of the ocean cut fuel costs by$2 million on its maiden voyage. By 2016, the Navy plans to have what it calls a Great Green Fleet, a complete carrier group running on renewable fuels with nuclear ships, hybrid electric surface vessels, and aircraft flying only biofuels. By 2020, the goal is to cut usage of fossil fuels by 50%. Once deployed in Afghanistan, the XFOB cut down on gas used in generators by over 80%. In the past, the Pentagon's innovations in computers, GPS, and radar have spun off into civilian life. In the future, the military's use of renewable energy can reduce dependence on foreign oil, increase operational security, and save lives and money.

JIM CHEVALLIER: A lot of the times, it is a culture change more than anything else. And the Department of Defense, over the years, has proved, time and time again, that they can lead the way in that culture change.

RICHARD ALLEY: If the US military is the largest user of energy in America, China is now the largest consumer on the planet. At 1.3 billion, China has a population about four times larger than the US, so average per-person use in CO2 emissions remain about 1/4 those of Americans. But like the US Military, China is moving ahead at full speed on multiple different sustainable energy options. And it pretty much has to. Cities are congested. The air is polluted. Continued rapid growth using old technologies seems unsustainable. This meeting in Beijing brought together mayors from all over China, executives from state-owned enterprises, and international representatives. The organizer was a US-Chinese NGO headed by Peggy Liu.

PEGGY LIU: Over 20 years, we're going to have 350 million people moving into cities in China. And we're going to be building 50,000 new skyscrapers, the equivalent of 10 Manhattans, 170 new mass transit systems. It's just incredible, incredible scale.

RICHARD ALLEY: This massive, rapid growth comes with a high environmental cost.

MARTIN SCHOENBAUER: They recognize that they're spending as much as 6% of their gross domestic product on environmental issues.

RICHARD ALLEY: In 2009, China committed $35 billion, almost twice as much as the US, TO energy research and incentives for wind, solar, and other clean energy technologies. It's attracted an American company to set up the world's most advanced solar power research plant. China now makes more solar panels than any other nation. But it's also promoting low-tech, low-cost solutions. Solar water heaters are seen on modest village homes. Some cities have them on almost every roof. PEGGY LIU: China is throwing spaghetti on the wall right now in terms of over 27 different cities doing LED street lighting, or over 20, 30 different cities doing electric vehicles. RICHARD ALLEY: But visit any city, and you can see that the coal used to generate more than 70% of China's electricity has serious consequences with visible pollution and adverse health effects. China uses more coal than any other nation on Earth, but it's also trying to find ways to burn coal more cleanly. PEGGY LIU: In three years, 2006 to 2009, while China was building one new coal-fired power plant a week, it also shut down inefficient coal plants. So it's out with the old and in with the new. And they're really trying hard to invent new models. RICHARD ALLEY: This pilot plant, designed for carbon capture and sequestration, was rushed to completion in time for Shanghai's 2010 World Expo. It absorbs and sells carbon dioxide and will soon scale up to capture 3 million tons a year that could be pumped back into the ground, keeping it out of the air. MARTIN SCHOENBAUER: Here in China, they are bringing many plants online in a much shorter time span it takes us in the US. PEGGY LIU: China is right now the factory of the world. What we'd like to do is turn it into the clean tech laboratory of the world. RICHARD ALLEY: If nations choose to pay the price, burning coal with carbon capture can offer the world a temporary bridge until renewables come to scale. PEGGY LIU: China is going to come up with the clean energy solutions that are cost-effective and can be deployed at large scale-- in other words, solutions that everybody around the world wants. RICHARD ALLEY: Can low-carbon solutions really give us enough energy to power the planet and a growing population? Let's put some numbers on how much energy we can get from non-fossil fuel renewables. Today, all humans everywhere on Earth use about 15.7 terawatts of energy. That's a big number. In watts, that's 157 followed by 11 0's, or 157 billion of those 100-watt light bulbs we used as a reference. To show what's possible, let's see if we can get to 15.7 terawatts using only renewable energy. I'm here in the Algodones Dunes near Yuma, Arizona. The Guinness Book of Records says it's the sunniest place in the world. There's barely a cloud in the daytime sky for roughly 90% of the year. 0.01%, 1/100 of 1%-- if we could collect that much of the sun's energy reaching the Earth, it would be more than all human use today. Today's technologies have made a start. This was the world's first commercial power station to use a tower to harvest concentrated solar energy. Near Seville, Spain, 624 mirrors stretch over an area of more than 135 acres, beaming back sunlight to a tower nearly 400 feet high. Intense heat produces steam that drives the turbine, which generates electricity. When completed, this one facility will be able to power 200,000 homes, enough to supply the entire nearby city of Seville. Remember our target of 15.7 terawatts? Well, the sun delivers 173,000 terawatts to the top of Earth's atmosphere, 11,000 times current human use. No way we can capture all of that potential energy at Earth's surface. But the deserts of America's Southwest, with today's technology, have enough suitable land to supply 80% of the entire planet's current use. Of course, there's one big problem with solar power-- night. But with more efficient transmission lines, and as part of a balanced renewable energy portfolio that includes storage, the sun's potential is vast. In tropical nations like Brazil, the sun heats water, makes clouds, and unleashes rainfall that feeds some of the planet's largest rivers. Iguazu Falls is a tourist attraction, one of the most spectacular waterfalls on Earth, where you can feel the immense power of falling water. The nearby Itaipu Dam on the border of Brazil in Paraguay produces the most hydroelectric power of any generating station in the world. This one dam supplies most of the electricity used in Sao Paulo, a city of more than 11 million. Sao Paulo is 600 miles away, but Brazil made the decision to build innovative, high-voltage direct current transmission lines to minimize energy loss. The Itaipu to Sao Paulo electrical grid has been in operation since 1984 and shows that renewable energy can go the distance. Dams can't be the answer for every nation. They flood landscapes, disrupt ecosystems, and displace people. But hydropower gives Brazil, a nation larger than the continental United States, 80% of its electricity. And worldwide, hydropower could contribute 12% of human energy use, ready at a moment's notice in case the sun goes behind a cloud. Brazil is also using its unique natural environment in another way. Its tropical climate provides ideal conditions for sugarcane, one of the Earth's most efficient plants in its ability to collect the energy of sunlight. Plantations like this one harvest the cane for the production of sugar and the biofuel called ethanol. The US is actually the number one producer of ethanol in the world, mostly using corn instead of cane. But ethanol made from sugar cane is several times more efficient at replacing fossil fuel than corn-based ethanol. Modern facilities like this one pipe back wet waste to fertilize the fields and burn the dry waste, called the gas, to generate electricity to run the factory. For Brazil, at least, ethanol works. Today, almost all cars sold in Brazil can use flex fuels. Drivers choose gasoline blended with 25% ethanol or pure ethanol, depending on price and how far they plan to drive. Local researchers say that if all the gasoline in the world suddenly disappeared, Brazil is the only nation that could go it alone and keep its cars running. Using food for fuel raises big questions in a hungry world. As of now, sugarcane ethanol hasn't affected food prices much. But there are concerns with corn. So here in the US, government labs like NREL, the National Renewable Energy Lab, have launched programs to see if biofuels can be made from agricultural waste. It does work, and researchers are trying to bring the cost down. So with plants capturing roughly 11 times human energy use, they're a growing opportunity. New Zealand takes advantage of another kind of energy. These are the geysers and hot springs at Rotorua on the North Island. Once, they were used by the native Maori people for cooking and bathing. Now geothermal power plants harvest heat and turn it into as much as 10% of all New Zealand's electricity. Many power projects are partnerships with the Maori, benefiting the local people and avoiding the "not in my backyard" problems that often complicate energy developments. Globally, geothermal energy offers three times our current use. But we can mine geothermal, extracting the energy faster than nature supplies it, cooling the rocks deep beneath us to make power for people. This energy exists even where you don't see geysers and mud pots, so it can be extracted without harming these natural wonders. A study by MIT showed that the accessible hot rocks beneath the United States contain enough energy to run the country for 130,000 years. And like hydroelectric, geothermal can provide peaking power, ready to go at a moment's notice if the sun doesn't shine and the wind doesn't blow. Mining energy from deep, hot rocks is a relatively new technology, but people have been using windmills for centuries, and the wind blows everywhere. Here's where the United States is very lucky. Let's take a trip up the nation's wind corridor, from Texas in the South to the Canadian border. Bright purple indicates the strongest winds. All along this nearly 2,000 miles, there's the potential to turn a free, non-CO2-emitting resource into electricity. But that takes choices and actions by individuals and governments. Here's what's been happening in West Texas. It's a land of ranches and farms and, of course, oil rigs and pump jacks. But in the early '90s, this was one of the most financially depressed areas in the state. Communities like Nolan Divide fell on hard times. Schools closed. People moved away. But since 1999, the new structures towering above the flat fields aren't oil derricks, but wind turbines. The largest number-- more than 1,600-- is in Nolan County. Greg Wortham is Mayor of Sweetwater, the county seat. GREG WORTHAM: It wasn't a philosophical or political decision. It was ranchers and farmers and truck drivers and welders and railroads. and wind workers. RICHARD ALLEY: Steve Oatman's family has been ranching the Double Heart for three generations. Steve may have doubts about the causes of climate change, but not about wind energy. STEVE OATMAN: But it's been a blessing. It helps pay taxes. It helps pay the feed bill. Rosco, 30 May. GREG WORTHAM: We talk about this being green energy because it pays money. The ranchers and the farmers call it mailbox money. They have to get up, and sweat, and work hard all day long. Things are pretty stressful. And if you can just walk to the mailbox and pick up some money because you've got turbines above the ground, that makes life a lot easier. RICHARD ALLEY: Each windmill can generate between 5,000and5,000and15,000 per year. So a ranch with an average of 10 to 20 turbines can provide financial stability for people who have always lived with uncertainty. STEVE OATMAN: I don't just believe in it because I make a living from it. It's something that's going to have to happen for the country. RICHARD ALLEY: So now, local schools have growing enrollments and funds to pay for programs. GREG WORTHAM: We had about$500 million in tax based in the whole county in 2000. And by the late part of that decade, in less than 10 years, it went up to $2.5 billion in tax value. RICHARD ALLEY: By the end of 2009, the capacity of wind turbines in West Texas totaled close to 10,000 megawatts. If Texas were a country, it would rank sixth in the world in wind power. The US Department of Energy estimates that wind could supply 20% of America's electricity by 2030. New offshore wind farms would generate more than 43,000 new jobs. That translates into a$200-billion boost to the US economy. Worldwide, wind could provide almost 80 times current human usage. No form of energy is totally free of environmental concerns or hefty startup costs. Some early wind farms gave little consideration to birds and other flying critters, like migrating bats. But recent reports by Greenpeace and the Audubon Society have found that properly sighted and operated turbines can minimize problems. Mayor Wortham, for one, welcomes wind turbines into his backyard.

GREG WORTHAM: We like them. Some people don't. But we're more than happy to export our energy to those states who want to buy green, but don't want to see green.

STEVE OATMAN: In the long run, I hope we have wind turbines everywhere they can produce energy. We need them. That's what America is going to have to do. That's the next stepping stone to save ourselves.

RICHARD ALLEY: The state of Texas has invested $5 billion to connect West Texas wind to big cities like Dallas and Fort Worth. Farther south is Houston, one of the most energy-hungry cities in the country. Its port is America's largest by foreign tonnage, and its refineries and chemical plants supply a good portion of the nation. But already, perhaps surprisingly, Houston is the largest municipal purchaser of renewable energy in the nation. 30% of the power city government uses comes from wind, with a target of 50%. And its mayor wants to cut energy costs and increase energy efficiency. ANNISE PARKER: I want to go from the oil and gas capital of the world to the green and renewable energy capital of the world. RICHARD ALLEY: Supported by federal stimulus dollars, the local utility is ahead of schedule to install smart meters. These will help consumers economize on energy use. The city has already installed 2,500 LED traffic lights using 85% less energy than traditional incandescent bulbs. That translates into savings of$3.6 million per year. City Hall thinks it can also improve air quality by changing the kinds of cars Houstonians drive.

ANNISE PARKER: If

RICHARD ALLEY: The city already operates a fleet of plug-in hybrids. Now it's encouraging the development of an infrastructure to make driving electric vehicles easy and practical. And in Houston's hot and humid environment, it helps to have an increasing number of energy-efficient, LEED-certified buildings. ANNISE PARKER: We're going to do it because it's the smart thing, because it makes business sense, and it's the right thing.

RICHARD ALLEY: Some estimates are that the US could save as much as 23% of projected demand from a more efficient use of energy.

ANNISE PARKER: Well, if you're going to tackle energy efficiency, you might as well do it in a place that is a profligate user of energy. And when you make a difference there, you can make a difference that's significant.

RICHARD ALLEY: Globally, efficiency could cut the demand for energy by 1/3 by 2030. Bottom line-- there are many ways forward, and we can hit that renewable energy target. And if next-generation nuclear is also included, one plan has the possible 2030 energy mix transformed from one relying on fossil fuels to one that looks like this, with renewables-- sun, wind, geothermal, biomass, and hydropower-- totaling 61%, fossil fuels down to 13%, and existing and new nuclear making up the balance. Another plan meets world energy needs with only wind, water, and solar. And in fact, there are many feasible paths to a sustainable energy future. Today's technologies can get us started, and a commitment to research and innovation will bring even more possibilities. We've traveled the world to see some of the sources the planet offers to meet our growing need for clean energy. There's too many options to cover all of them here. And besides, each nation, each state, each person must make their own choices as to what works best for them. But the central idea is clear. If we approach Earth as if we have an operator's manual that tells us how to keep the planet humming along at peak performance, we can do this. We can avoid climate catastrophes, improve energy security, and make millions of good jobs. For "Earth-- The Operator's Manual," I'm Richard Alley.

NARRATOR: "Earth-- The Operator's Manual" is made possible by NSF, the National Science Foundation, where discoveries begin.

[MUSIC PLAYING] For the annotated, illustrated script with links to information on climate change and sustainable energy, web-exclusive videos, educator resources, and much more, visit pbs.org. "Earth-- The Operator's Manual" is available on DVD. The companion book is also available. To order, visit shoppbs.org, or call us at 1-800-PLAY-PBS.