Can We Cool the Planet? | Full Documentary I NOVA | PBS

[Music] our rising temperatures driving earth's ecosystems past a point of no return we can't go back there is no path backwards every year the damages are worse we have promising technologies that put solutions within our grasp but are we reaching far enough we have to have emissions cut to zero even if we stop emitting co2 we still have the co2 we've already admitted so scientists are building a new toolkit it has power to ensure a prosperous future our society has to survive we need to reduce the heating effect cutting edge solutions it's going to be

revolutionary it's like science fiction there's the balloon up there and high risk measures i really hope we'll never have to do this it's really important that humanity has a backstop in a race to discover can we call the planet right now on nova [Music] [Music] it's a new time in the earth's history in which we're not just inhabiting our planet we're operating as stewards of the very thing that we're living on since the industrial revolution humanity has been running an unintentional experiment in earth's atmosphere pushing the climate to new extremes things are going to get

hot well you can attitudes have changed rapidly because everyone can see for themselves the climate change that is occurring a child born today will witness across her lifetime a planet transformed by rising temperature [Music] how did we get here every time you get in your car every time you fly a plane every time you turn the heat on all of those things are putting carbon dioxide into the atmosphere and if there's more carbon dioxide in the atmosphere there's a higher temperature and now temperatures have started to spike if we keep pumping billions of tons of

co2 into the atmosphere each year we really will cook ourselves literally in the end to stop the worst impacts of planetary heating we need rapid emissions cuts starting now the developed nations of the world need to go from the energy system they have now to one that emits nothing zero in 30 years time the good news is we know how to do that renewables now are the cheapest form of electricity on two-thirds of the earth's surface and it's going to be everywhere a world of carbon-free energy is coming but climate impacts are coming faster lasers

are at power there it is so scientists are opening a second front in the battle suite it has power bringing new technologies to bear on the way we fight climate change we now have so much data this is going to be the game changer there are a whole class of solutions to actually get this job all the way done by removing co2 from the air this little guy this is just the beginning converting co2 from a waste to a resource we see this kind of as a testing ground even extreme measures like shielding us from

the sun there's been a technical revolution in the last few years that's unlike anything we've seen in the previous hundred this is a problem with a solution can a new wave of climate tech take us the rest of the way to turn down the global thermostat we need to look at everything that's out there natural solutions co2 sequestration solar geoengineering there may be this idea out there that nobody has come up with it that could be really transformative [Music] cooling the planet means first stopping more co2 from entering the atmosphere and then finding ways to

remove it but just how much co2 are we talking about imagine you filled the national mall all the way from the lincoln memorial to the capitol steps with coal and you piled it up all the way to the top of the washington monument 10 times that would be a gigaton of coal giga means billion so that's a billion tons now we actually burn 10 times that much carbon every year people actually go dig that stuff up out of the ground 10 billion tons of it and set it on fire in power plants in engines in

factories all over the world and then because that carbon is reacted with oxygen 10 gigatons of carbon is burned but it creates 37 gigatons of co2 at our current rate that's just one year of co2 emissions to blunt the impacts of heating the planet we need to shrink that number to zero but there's another problem the gigatons that came before the single most important fact about climate change is that the carbon dioxide that we emit into the atmosphere stays there for thousands of years year after year we live with the carbon dioxide we've added over

time nearly 1 000 metric gigatons since the industrial revolution began almost everything we emit stays there that's staying there until you do something about taking it out pulling co2 out of the air it sounds futuristic but it's a problem we've encountered before remember apollo 13. it was all about co2 filtering right that's that was the big problem how to get the co2 out of the air in 1970 following an accident the crew of apollo 13 aborted a mission to land on the moon forced to return to earth in a smaller capsule the astronauts faced a

big problem you're in confined spaces people exhale co2 you need to remove that co2 every exhale caused carbon dioxide to build up making the air increasingly toxic okay now let's everybody keep cool let's solve the problem but let's not make it any worse by guessing the astronauts survived by modifying their air scrubber to remove more carbon dioxide inside the scrubber negatively charged sites on the filter polarize and bond with the co2 removing it from the air could something like this work in earth's atmosphere there's not a lot of co2 in the air compared to nitrogen

oxygen imagine a box with 10 000 ping-pong balls in it and four of them are painted black those are the co2 molecules trying to find those four balls out of that big box full of ping pong balls is hard [Music] removing co2 from a spacecraft is one thing removing it from our atmosphere poses a much bigger challenge [Music] is it realistic most people to whom we told we are taking co2 out of the air would say you're crazy but here you see a full-scale direct air capture plant you see it consists of 12 individual modules

capturing the co2 out of the air jan wurtzbacher is a co-founder of climb works a swiss startup specializing in what's called direct air capture to this side we suck in ambient air with 400 ppm that's 400 parts per million co2 [Music] and on the other side we expel about 100 ppm co2 content so three quarters are kept inside a filter with highly reactive chemicals called amines catches even small concentrations of co2 heating the filter then breaks the bond you release the co2 and you can extract pure concentrated co2 and then you start all over again

but generating the energy to do this can produce its own co2 their solution for that is garbage here we are on top of the waste incineration plant the reason why we're here is the main energy source for a process of co2 capture from the air waste heat from the incineration process heat that would have been wasted instead heats the filters inside the array which capture nearly 1500 metric tons of pure co2 a year about what's expelled from the tailpipes of 300 cars [Music] once you've pulled co2 out of the atmosphere with a direct air capture

machine the question is what to do with it the big picture is taking one percent of co2 out of the atmosphere within the next five to ten years that is roughly 400 million tons and store it underground [Music] could we put carbon right back where we found it underground there are lots of rocks near the surface of the earth that would want to bond spontaneously with co2 there's enough of these kinds of minerals that you could remove all of the atmospheric co2 many many times over [Music] one of the best places to try that out

is iceland here we are the land of ice and fire we have eruptions we have earthquakes iceland is an island formed out of volcanic rock called basalt we see the bustles like mountains here around me and actually extending several kilometers downwards basalt is porous rock that readily bonds with co2 over centuries sandra schneiber's daughter's team has found a way to speed up that process carpex is the method of capturing co2 and turning it into stone magic but it's magic that already occurs in nature carb fix is turning one third of the co2 from this power

plant into solid rock in less than two years the key is water inside this scrubber gaseous co2 is dissolved in water to react with basalt more quickly this crop is actually just a giant soda stream the fizzy water is then pumped into injection wells this is actually my favorite part of it all from here the magic starts to happen this pipe extends to over 2000 feet and there we finally release this fluid to the rock once inside the basalt the dissolved co2 reacts with metals in the rock to form new solid minerals like calcium carbonate

once we have injected the co2 into the rock it's there forever and sandra is looking beyond iceland she's test driving a direct air capture unit that can suck up co2 we don't need a power plant this can be done anywhere where you have a formation to store your co2 what that means is you can go backwards you can reverse the process of emitting carbon dioxide into the air negative emissions technologies like direct air capture could play a role in reaching net zero the moment when humans remove as much co2 from the atmosphere as they put

in so why isn't this the ultimate answer to our co2 problem these technologies are very hard to scale up to a meaningful amount the base module of our direct air capture plant that's a 40 foot shipping container in order to take one percent of global emissions out of the air we would need 750 000 shipping containers all to remove just half a gigaton of our annual emissions direct air capture is very expensive and it takes energy to suck co2 out of the air so i hope you're not imagining direct air capture vacuuming up the entire

fossil fuel emissions of the world because that ain't gonna happen we'll need lower cost clean energy everywhere before the promise of direct air capture can meet the scale of the problem themselves so some are exploring another idea recycling our emissions correction factor 0.7 we need to think about this problem very pragmatically we can electrify a lot of things but there's certain parts of the energy system that are extremely hard to decarbonize a good example is aviation you couldn't build today a commercial airplane for long distances which could fly on batteries you would just carry way

too much weight this is physically impossible there is no way around jet fuel we need to be producing fuel that when you burn that fuel doesn't emit carbon dioxide remove go ahead and rotate aldo steinfeld thinks he's found a way [Music] perfect we are on target we have demonstrated that we can produce liquid hydrocarbon fuels from two ingredients sunlight and ambient there [Music] it may sound like science fiction or magic but it is chemistry is heat transfer and also it's a lot of engineering [Music] aldo captures co2 and water from the air and feeds them

into a solar reactor solar radiation is reflected and concentrated at the focus by a factor of 5000 it is like the intensity of 5 000 suns concentrated solar energy drives a reaction that generates a synthetic gas which can then be converted into fuels and here in my hands i have an example of solar methanol [Music] when it's burned the carbon in this fuel returns to the atmosphere but since it was harvested there the net co2 is zero this is called carbon neutral and hundreds of scientists like aldo are working to make carbon neutral fuels a

reality if they succeed annual net emissions could drop by as much as 1 billion tons it's going to be something revolutionary but with these fuels up to six times the cost of standard fuel it's a revolution that has only just begun but it raises the question what else can we make by recycling co2 carbon is this incredible building block think of it like those little sort of lego toys that we used to have only there's four little plug-ins for it so you could bond carbon to carbon to carbon to carbon to build all kinds of

stuff imagine a world where everything around you is made from carbon emissions from the products you use every day to the clothes you wear this ad from the xprize foundation pitches a future where recycled co2 shapes our world and a 20 million dollar bounty to make that a reality we announced hey there's a 20 million dollar prize out there we're looking for innovators around the world if you know how to convert co2 into a useful material consider entering this price we are trying to help catalyze the whole ecosystem of companies of investors of people that

can deploy these technologies the carbon x prize has brought five of the finalists here to put their innovations to the test [Music] they're setting up shop next to a plentiful supply of co2 they've got to take the emissions from a natural gas power plant and convert those into whatever material they like from toothpaste to yoga mats to watches [Music] each team will be scored on its net co2 reduction you could have a process that uses up a lot of co2 to make its product but in the end just produces more co2 than it uses up

okay we don't want that yep we want things that actually are reducing co2 overall we just moved to site about two weeks ago a day later and i think we'd have snow in here that would be shelling out a so sinha is the ceo of carbon upcycling technologies or cut we're a carbon tech company which takes carbon emissions and converts them into solid nanomaterial products for use in anything from cutlery to car parts but to make the biggest impact on co2 and win this competition kapoor is focused on cement cement is an essential component of

concrete the glue that binds it together but producing it creates a lot of co2 cement production accounts for over eight percent of the world's annual emissions if all the cement producing companies were a country they would be the third largest emitter in the world [Music] the porv's process converts co2 into a needed ingredient for concrete and he believes it will also reduce the amount of cement that concrete manufacturers need he starts with an industrial waste powder left over from burning coal called fly ash with the reactor that we have behind us we're scaling up and

commercializing an enhanced fly ash where the fly ash has been chemically activated to capture co2 as the reactor spins the fly ash we inject co2 ball bearings coated with a catalyst speed up the chemical reaction as the ball bearings rise and fall the motion breaks up the fly ash and roughs up the surface so that more co2 can be absorbed as the co2 penetrates the fly ash surface it forges tunnels along the way in effect carbon dioxide has bonded with fly ash to create a nanoparticle with more reactive surface area which combine concrete together and

strengthen it with less cement if concrete producers are able to use less cement in their production they could considerably reduce the emissions that come from their industry the question remains is it strong enough for concrete makers to buy it we just want to make sure that the technology is good and that it works really well one of our local partners is a family-owned calgary-based concrete business called burnco burnco is testing the strength of concrete held together using a porv's nanoparticle when the cylinder breaks we will have our final pressure read up there these are impressive

results in normal production you're looking for changes of three to four percent and these are showing results in in double digits it's very encouraging we're very confident that we can get up to a 10 reduction in the amount of cement used today but our real target is to get that number up to 20 or 25 then we start talking about significantly moving the needle on the 37 gigaton a year number but even if these new technologies can scale to their full potential they could only lock away a fraction of our emissions the total volume of

co2 that we create in the atmosphere is so much bigger than the volume of any product i think people are losing track of the central issue which is we have to reduce net co2 emissions easiest thing believe it or not is to burn less carbon right to not generate the co2 in the first place carbon-free energy like wind solar and nuclear power can drive down most of our annual emissions and the rest could be offset with negative emissions technologies that remove co2 from the air we will do it we will get to the day without

a global celebrations we get to net zero day we brought human co2 emissions to zero i think it'll happen in my lifetime it is doable but on that day we have not solved the climate problem all we've done is stop making it worse the problem that remains is heat the temperature of the earth is determined by heat coming in from the sun and heat going out by radiation out to space every single day co2 from our past emissions traps energy in the earth's system the same amount of energy as 500 000 of the bomb dropped

on hiroshima detonating at once that heat is altering our climate what's it going to be like when you know three months of the year 115 degrees when vast ecosystems have died out people are going to push for for doing something about this and many fear earth is approaching a tipping point that will trigger rapid change the uncertainties that keep me up at night are what if we aren't doing enough and there's some monster lurking behind the door that all of a sudden comes out into the world among us [Music] it's a good idea that humanity

has some sort of a backstop technology something to do if we get surprised in a way that is very very dangerous some think that backstop could be solar geoengineering it's a way to intercept sunlight coming into the planet to cool the planet the core idea is that humans might deliberately alter the earth's energy balance to compensate for some of the warming and climate changes that come from greenhouse gases geo-engineering the climate is a controversial idea but nature can show us examples of where we might start clouds the cloud is just water that's condensed down onto

particles into small droplets these collections of droplets are in effect floating sun reflectors clouds play a huge role in controlling the climate because they control the reflectivity of the planet especially over the ocean you go from sunlight hitting a very dark surface where a lot of the sunlight is absorbed to sunlight hitting extremely bright surface reflecting a lot of that sunlight back to space sarah dougherty of the marine cloud brightening project is working on a way to boost that effect can we add really small sea salt particles to clouds in a way that significantly increases

their brightness and do so over enough of the ocean that we would have a significant impact on the global temperature but how do you make salt water particles and launch them up into clouds what we need is a nozzle like you'd see in a sort of a snow blower except the particles that we want to produce are about a thousandth the width of a human hair so sarah's working with an engineer who knows all about machines for spraying super fine droplets a concept developer of the earliest inkjet printers in a different life i was an

engineer and a physicist i i couldn't enjoy retirement anymore and just sit there watch what's going on once you know what's going to happen or might happen you can't sit down and say yeah i'm just gonna enjoy life armand and his team of retired scientists have been developing a cloud brightening machine for over 10 years they have been self-funding this research in borrowed lab space park is a really good place for them because of our history with aerosols park or palo alto research center has infused the marine cloud brightening project with fresh expertise and cutting-edge

tools here kate murphy can make aerosols from just about anything this is our deep conditioner aerosols are tiny particles suspended in air this is ketchup for clouds they're not going to spray ketchup but kate can help the team design a nozzle for spraying salt water let me just give it a little water okay okay kate's expertise will help optimize the size and speed of the particles to propel them into marine clouds so you're going to be redesigning the nozzle based on your computational fluid dynamics well we hope to be able to understand the effect of

multiple nozzles so we would want to measure things like velocity and direction these crisscross laser beams can help reveal whether our mons nozzle will hit the mark the lasers are at power um it looks like our signal is pretty good so can you measure the vertical velocity do you have a measurement of that that would be of great interest to us park will be working on developing a full spray system and then we would want to move outside into real atmospheric conditions on the other side of the world outdoor research has already begun armand and

the team have shared their insights with researchers in australia who are testing cloud brightening as a way to cool the waters surrounding the threatened coral of the reef that project is targeted and local but some estimate that cloud brightening on a global scale could offset all the heat trapped by our co2 emissions it will probably take a good 15 to 20 years to do all of the research involved with understanding how big of an effect we could have by brightening clouds and also what all of the side effects might be those side effects are not

well understood and could include disruptions to ecosystems and rainfall patterns further research is needed we have kids we have grandkids we're doing it for their futures you know and frankly we are all in this together whether you have kids or not [Music] we're more than individuals our society has to survive [Music] we're facing a problem that's getting worse not better do we need to consider more extreme measures in 15 years or 20 years humanity may find itself at a point where impacts are so big that there's a very large demand for fast action to prepare

frank is starting now by researching a controversial technology that goes further than brightening clouds it would brighten the entire planet putting particles in the stratosphere could reflect back some sunlight to space reducing the amount of sunlight that hits the surface and cooling down the planet the effect would be immediate we know this works because every time a big volcano goes off and it injects aerosols into the stratosphere the planet cools down that's the idea behind solution engineering it's like drawing a curtain over the face of the earth the first time you hear about this you

think well that sounds like a really bad idea how could that not go wrong [Music] but what we're doing to climate as humans that really to me starts seeming also quite scary and crazy and really worrying the fact is the co2 is in the atmosphere without a time machine we can't make it go away we want to in the long run do carbon removal but during the time that concentrations are high we might want to do solar geo sharing to reduce the climate risk [Music] all that is hard mounted to us yes that is exactly

what i want and then there's the balloon up there frank and david's team is designing a first of its kind experiment called scopex to investigate the impacts of solar geoengineering the only place i see that conversation getting sticky is where we do risk assessment on it if you put these particles out what happens when these come back down what happens when it gets into the environment are we endangering people there are lots of things that we might need to know where the existing experimental background is bad you actually have to go out and make measurements

the plan is to launch a 100-foot balloon into the stratosphere and release a plume of reflective aerosols we want to put out the particles of calcium carbonate for example and then go back through this plume and see whether the evolution of the air is the way we predict it based on our laboratory results this is an experiment on a very small scale and in fact the amount of material we're putting out is less than a normal airplane flight puts out scopex may be small but many fear a large-scale manipulation of earth's atmosphere could trigger a

cascade of dangerous unintended consequences that ripple across the planet nothing in our scientific capability actually enables us to understand the complexity of the interactions that would be set loose it's not just that it lowers the temperature but what are some of the other effects on the hydrologic cycle or on heat waves and droughts this is a manipulation of the earth's atmosphere on a huge scale what happens if things go wrong scopex is designed to start answering those questions but there may be effects beyond the physical that no experiment can predict if we think that there's

this solution out there then people may think it doesn't matter if you're polluting the planet the root of the concern is that solar geometry and research however well-intentioned will be used an excuse for big fossil fuels to fight emissions cuts it's just like a sci-fi dystopian novel or something where we continue to just belch all this co2 into the atmosphere but hey it's okay because we got these little umbrellas that are you know hiding us from the sun solar gma sharing does not get us out of the ethical and physical requirement to cut emissions but

with so much uncertainty some think we're better off investing in a different kind of machine one developed in nature's own laboratory over millions of years and with a proven record of safely drawing down gigatons of co2 [Music] trees i'm going on a hike through a forest i have a tendency to look up and say okay oh that tree's about 60 feet tall and then i try to calculate in my head okay how much carbon is stored in that tree i think this is good lola fata jimbo is a research scientist at nasa's goddard space flight

center sweet it has power limit things work she and her team are about to see these century-old trees in a new light green lights there's carbon all around us if you think of trees as a machine then trees would be a carbon capture machine when we're looking at trees about half of that weight is carbon lola and her team want to know how much carbon is stored in this entire forest to measure each and every tree they're using a special kind of tool lasers we're using a terrestrial laser scanner that shoots out billions of laser

pulses every second and then measures the distance from the instrument to whatever is around it the data that we get back generated point cloud billions of data points form a 3d measurement of forest volume and the carbon stored within it's so dense that it almost looks like a photograph it's like science fiction this scan may look like reality but this is data it reveals that in an area the size of a football field these trees are storing roughly 150 tons of carbon all pulled out of thin air which prompts tom crowther to ask could we

enlist trees in the race to draw down co2 our lab is urgently trying to figure out how we increase the area of forest across the globe to capture as much carbon as we possibly can in the fight against climate change tom's findings began with a surprising discovery we thought there was around 400 billion trees on the planet but we showed that there's in fact around three trillion trees [Music] there's more trees on the surface of our planet than there are stars in the galaxy the big question is how many more trees could we add in

order to understand the global forest system we need to map a lot of things we need to know where forests are where forests could be we collect our data from millions of locations around the world where scientists have been on the ground evaluating those ecosystems data like leaf fall patterns in forests around the world i'm trying to understand the seasonal rhythm of plants microscopic organisms like the tiny worms that feed the soil beneath the trees in just this clearing there's millions and millions of nematodes living in the soil decades of satellite data on factors like

rainfall and temperature when i look at ecosystems most of the time i'm looking from the top down and with all of that data we can start to see the patterns across the globe using remote sensing information from satellites and machine learning technologies we can generate maps that can predict which regions can support new trees and which ones cannot this really is a data revolution the detail is astonishing and the potential for new forests is vast outside of urban and agricultural areas there's room for about 2.5 billion acres of forest the area we identified equals the

size of the united states so there's a huge area available for restoration enough space for trillion new trees all sucking co2 out of the air if we were to restore a trillion trees the right types of trees in the right kinds of soils and have them grow to full health they could store an additional 205 gigatons of carbon to put that into context we've released nearly 660 gigatons of carbon into earth's systems since human industrial activity began restoring global forests and conserving the vital forest that we currently have could take a huge chunk out of

that excess carbon this is a really massive carbon drawdown solution and we knew that this was going to make an enormous flash but these findings also made waves that study is causing a lot of debate on the one hand a lot of people are talking about the potential of restoration of force on the other hand i would say um a lot of people are very upset about it [Music] the uncertainty around the amount of carbon that's stored in trees is so high that we can't really make any informed recommendations on how many trees we need

to plant lola wants to use new technology from nasa to fill those areas of uncertainty with hard data we have over 20 earth observing satellites right now from nasa alone looking at our planet earth but what we're seeing is all in two dimensions what we're missing here is the third dimension enter a powerful new tool called jedi with the same laser technology used in her terrestrial scanners lola can get a three-dimensional measure of forest carbon from the international space station jedi stands for the global ecosystem dynamics investigation which is what you're seeing right here this

is about the size of a fridge you can see the lasers shooting down out of the bottom of the instrument towards the surface of the planet we actually can see a full profile of plant materials the game changer here is that this is going to be for the first time a near global data set jedi will give clearer insight on the carbon new forests could store but equally important it can pinpoint the old forest carbon we must preserve forests are really important for our water supply forests protect us from heat forests breathe they breathe in

some ways just like we do when you lose a lot of the ecosystem services that forests provide that has a direct impact on the well-being of people [Music] but on an increasingly populated planet trees are not the only living things competing for land we already use all of our agricultural land to feed our existing population and over the next 30 years food demand is going to double if you take land to solve the climate problem you create another problem so is there a solution that can solve more than one problem at a time some people

are looking at ways in which forests can help slow climate change our research is somewhat different than that we're looking at grasslands i want to have enough so that we can do experiments in california wendy silver is looking for a way to pull down co2 right where we grow our food earth's grasslands this is a classic beautiful annual grassland grasslands grow in places where there's drought for part of the year and these grasses have developed great tools for getting water particularly by growing more roots and anytime plants invest a lot of their energy into roots

it's like injecting carbon into the soil but tilling releases that carbon and degrades the soil and producing our food creates even more problems we all eat food every day we have to grow that food and we create a lot of organic waste in the process when organic waste sits in a landfill or slurry pond it creates an oxygen deprived environment favorable to certain microbes which in turn produce methane a greenhouse gas 34 times more potent than co2 we're trying to tackle three big problems waste degrading soil health and climate change we came up with something

relatively simple composting in composting food waste is regularly turned adding oxygen to the mix and keeping the methane producing microbes at bay it creates this organic and nutrient-rich resource like a slow-release fertilizer that helps plants grow by turning a waste into a nutrient compost can boost plant growth and potentially turn vast stretches of earth's food crops into a carbon-storing juggernaut [Music] we now have 10 years of data showing that just a one-time dusting of compost onto the soil surface can have a long-term impact on plant growth and increase carbon storage and soils wendy's research shows

that a single layer of compost can increase plant growth by up to 78 and increase soil carbon by up to 37 percent for three years the real challenge is to extrapolate from little tiny soil samples in the field to big chunks of california or the globe that's a huge challenge as the hunt for solutions continues in the decades ahead stopping our emissions remains the most urgent challenge of today if we really didn't do anything to limit carbon emissions we would have climate changes as big as the changes from the glacial to interglacial state and do

that in one human lifetime with huge potential impacts the more of a mess we make the bigger of a mess we'll have to clean up we today get to decide whether to continue along this path [Music] or to dramatically shift our economy off of coal oil and gas every big transformative solution starts small it starts with a couple people talking they make a small version they make a bigger version more people pile in this is one solution but we need thousands of solutions if you want to tackle climate change there's no one magic silver bullet

that will solve this problem the main challenge that we have is that these transitions don't happen overnight we have the tools already but we really have to start moving we need better transportation systems we need solar power and wind power and water power and probably nuclear power we need to plant trees we need to manage our farms better we need direct air capture i i think we probably need it all we have to start really looking at what can scale up and be maintained for decades if not centuries that's the challenge here but it's an

incredibly important challenge 15 years ago no one would have predicted that the emissions in developed countries around the world would be dropping not fast enough yet but that gives me hope and should give everyone hope that with a combined might of human ingenuity we can actually solve this problem [Music] [Music] to order this program on dvd visit shop pbs or call 1-800 play pbs episodes of nova are available with passport nova is also available on amazon prime video [Music] [Applause] [Music] [Music] you