0:00:06 > 0:00:11This is the Earth, our planet.
0:00:11 > 0:00:14Home to millions of different species.
0:00:14 > 0:00:17But only one species dominates everything.
0:00:20 > 0:00:23Human beings.
0:00:23 > 0:00:27There are nearly seven billion of us living on the Earth.
0:00:27 > 0:00:32And the human population is increasing by more than two people every second.
0:00:32 > 0:00:34200,000 people every day.
0:00:34 > 0:00:39Nearly 80 million people every year.
0:00:39 > 0:00:44Each additional life needs food, energy, water, shelter
0:00:44 > 0:00:48and hopefully a whole lot more.
0:00:55 > 0:00:57Today we're living in an era
0:00:57 > 0:01:03in which the biggest threat to human wellbeing, to other species,
0:01:03 > 0:01:07and to the Earth as we know it, might well be ourselves.
0:01:07 > 0:01:11The issue of population size is always controversial
0:01:11 > 0:01:15because it touches on the most personal decisions we make.
0:01:15 > 0:01:18But we ignore it at our peril.
0:01:20 > 0:01:24There's absolutely no doubt at all that the world's population will continue to grow.
0:01:24 > 0:01:26The only question is by how much.
0:01:27 > 0:01:32More than a billion people on the planet already lack access to safe, clean drinking water.
0:01:32 > 0:01:36And we know things are going to get more difficult as the population continues to grow.
0:01:36 > 0:01:43We need to double the amount of food that we have available to us as soon as possible.
0:01:43 > 0:01:48Such a scale of change will leave no-one untouched.
0:01:48 > 0:01:51Keep in mind that when the Titanic sank, the first-class cabins
0:01:51 > 0:01:54went to the bottom just as quickly as the steerage.
0:02:03 > 0:02:08I was born into a world of just under two billion people.
0:02:08 > 0:02:13Today there are nearly seven billion of us.
0:02:13 > 0:02:17Whenever I hear those numbers I can honestly say I find it incredible.
0:02:17 > 0:02:21Triple the number of human beings in what seems like the blink of an eye,
0:02:21 > 0:02:24and the world transformed utterly.
0:02:27 > 0:02:30Human population density is a factor
0:02:30 > 0:02:34in every environmental problem I've ever encountered,
0:02:34 > 0:02:37from urban sprawl to urban overcrowding,
0:02:39 > 0:02:44disappearing tropical forests to ugly sinks of plastic waste.
0:02:44 > 0:02:48And now the relentless increase of atmospheric pollution.
0:02:51 > 0:02:55I've spent much of the last 50 years seeking wilderness,
0:02:55 > 0:03:01filming animals in their natural habitat and to some extent avoiding humans.
0:03:03 > 0:03:08But over the years, true wilderness has become harder to find.
0:03:13 > 0:03:19I can't pretend that I got involved with filming the natural world 50 years ago
0:03:19 > 0:03:23because I had some great banner to carry about conservation. Not at all.
0:03:23 > 0:03:30I've always had huge pleasure in just watching the natural world and seeing what happens.
0:03:39 > 0:03:44I made those films because it was a hugely enjoyable thing to do.
0:03:44 > 0:03:49But as I went on making them, it became more and more apparent
0:03:49 > 0:03:53that the creatures which were giving me so much joy
0:03:53 > 0:03:56were under threat.
0:03:57 > 0:04:01The fun is in delighting in the animals.
0:04:01 > 0:04:04But if you do that you owe them something,
0:04:04 > 0:04:07and so you have an obligation to speak out
0:04:07 > 0:04:10and do what you can to help protect them.
0:04:13 > 0:04:17I support a group called the Optimum Population Trust
0:04:17 > 0:04:19which campaigns to reduce birth rates.
0:04:19 > 0:04:22Because I think if we keep on going,
0:04:22 > 0:04:24we're not only going to damage nature,
0:04:24 > 0:04:29we're likely to see more and more inequality and human suffering.
0:04:29 > 0:04:33In this programme I want to see how population growth
0:04:33 > 0:04:37will affect our ability to obtain our most basic needs -
0:04:37 > 0:04:40water, food, and energy.
0:04:40 > 0:04:44And to see if it's possible to answer the question,
0:04:44 > 0:04:47how many people can live on Planet Earth?
0:04:50 > 0:04:52Human beings are good at many things.
0:04:52 > 0:04:58But thinking about our species as a whole is not one of our strong points.
0:04:58 > 0:05:02I don't even think I could tell you how many people live in this country.
0:05:02 > 0:05:05- A googol? - Yeah, I would say a googol.
0:05:05 > 0:05:08- TRANSLATION:- I know India's population is 1.1 billion
0:05:08 > 0:05:11but I don't know the population of the world.
0:05:11 > 0:05:13I'd say six billion off the top of my head.
0:05:13 > 0:05:19TRANSLATION: I've got no idea how many people live on the planet, no idea!
0:05:21 > 0:05:26Luckily, the size of the human population is studied very closely.
0:05:26 > 0:05:30By and large, every human birth and death throughout the world
0:05:30 > 0:05:32has been recorded for the last 60 years.
0:05:36 > 0:05:40The data is kept here in New York City, at the United Nations.
0:05:48 > 0:05:54Hania Zlotnik, head of the UN Population Division, is in charge of those precious numbers.
0:05:56 > 0:06:01This was the old type of working, when I arrived at the UN.
0:06:01 > 0:06:03I worked with these types of files.
0:06:03 > 0:06:07They are very well-organised but they look old.
0:06:07 > 0:06:12Now we do it via computer and it's somehow not the same thing as feeling the data.
0:06:15 > 0:06:17I am a numbers person, yes, definitely.
0:06:18 > 0:06:21'My mission is to be the bean counter.'
0:06:21 > 0:06:24That means we are the thermometer telling you
0:06:24 > 0:06:28that the planet is getting hot or cold in terms of population change.
0:06:28 > 0:06:32The UN do much more than just keep records.
0:06:32 > 0:06:34They make projections into the future.
0:06:34 > 0:06:37And their figures are staggering.
0:06:37 > 0:06:40The human population is still growing.
0:06:40 > 0:06:43One expects that at the very least it's likely to add
0:06:43 > 0:06:47about 2.3 billion people by middle of the century.
0:06:47 > 0:06:50We have 6.8 billion today.
0:06:50 > 0:06:54We're expecting to get the seventh billion in the next three to four years.
0:06:54 > 0:06:58And then that by mid-century we'll have something like nine billion.
0:07:02 > 0:07:05In the next 40 years, the Earth will need to accommodate
0:07:05 > 0:07:08nearly three billion more people.
0:07:08 > 0:07:11That's more than the current population of the whole of Europe,
0:07:11 > 0:07:16the whole of Africa, North and South America combined.
0:07:17 > 0:07:20How can we be so sure of this prediction?
0:07:20 > 0:07:24Well, we know that there are more than a billion teenagers alive today
0:07:24 > 0:07:27and most of those teenagers will have children of their own
0:07:27 > 0:07:29and live long enough to become grandparents.
0:07:29 > 0:07:32And that's all that needs to happen
0:07:32 > 0:07:37for there to be nine billion humans alive in 2050.
0:07:37 > 0:07:40It's not people having huge families.
0:07:40 > 0:07:44It's just a lot of people doing what humans naturally do.
0:07:48 > 0:07:52We also have a good idea of where these additional people will live.
0:07:52 > 0:07:56There are likely to be ten million more people in Britain.
0:07:56 > 0:08:00100 million more in the USA.
0:08:00 > 0:08:05India will overtake China to become the most populous country in the world.
0:08:07 > 0:08:09The population of some countries will shrink -
0:08:09 > 0:08:13Japan, Russia, Germany, and much of Eastern Europe.
0:08:15 > 0:08:19The places that will experience the most rapid growth
0:08:19 > 0:08:22are also the least developed countries in the world.
0:08:22 > 0:08:25Afghanistan's population will double.
0:08:25 > 0:08:28Most of Sub-Saharan Africa will double.
0:08:28 > 0:08:32Niger's population is predicted to more than triple.
0:08:34 > 0:08:37I think everyone living through the next 50 years is going to be
0:08:37 > 0:08:40affected by these demographic changes, wherever they are.
0:08:43 > 0:08:47For most of human existence, our population size
0:08:47 > 0:08:51was kept in check by nature, just as it is for other animals.
0:08:51 > 0:08:55If there's plenty of water, food and materials for shelter,
0:08:55 > 0:08:56a population will thrive.
0:08:58 > 0:09:03But when disease, famine or drought strike, life can be cut short.
0:09:09 > 0:09:13The history of humanity is one of overcoming these environmental limits,
0:09:13 > 0:09:16but it took us a very long time to achieve.
0:09:24 > 0:09:29On the horizontal axis here we have time over the last 10,000 years.
0:09:31 > 0:09:33On the vertical axis here we have
0:09:33 > 0:09:36the size of the human population in billions of people.
0:09:38 > 0:09:40Over the last 10,000 years,
0:09:40 > 0:09:44in general there's been very little change.
0:09:44 > 0:09:45It's a very boring picture.
0:09:45 > 0:09:52But from about the year 1800 onwards you have a major increase,
0:09:52 > 0:09:55a very large increase in the world's population
0:09:55 > 0:09:57from about 1 billion up to 7 billion today.
0:09:57 > 0:10:04Basically what this increase in population represents is control of death rates.
0:10:04 > 0:10:10Death rates have been reduced because infectious diseases -
0:10:10 > 0:10:15cholera, smallpox, malaria, measles, those sorts of things -
0:10:15 > 0:10:17have been massively reduced.
0:10:17 > 0:10:22On average for almost all of human history, a man and a woman
0:10:22 > 0:10:25were only survived into adulthood by two of their children
0:10:25 > 0:10:28and that's why the world's human population didn't increase.
0:10:29 > 0:10:32Extending life by controlling disease
0:10:32 > 0:10:37is perhaps one of the greatest achievements of humanity.
0:10:37 > 0:10:41I was born into a world of 2.5 billion
0:10:41 > 0:10:44and I'm seeing it almost triple in my lifetime.
0:10:44 > 0:10:48And life has not gotten worse.
0:10:48 > 0:10:51In fact for most of the population of the world,
0:10:51 > 0:10:54life has gotten better in these 50 years.
0:10:56 > 0:11:00Living healthily and long has consequences - population growth.
0:11:03 > 0:11:07Just as the human population was starting its unprecedented growth spurt
0:11:07 > 0:11:11in the late 18th century, this was published.
0:11:11 > 0:11:15It's a first edition of An Essay on Population
0:11:15 > 0:11:19by the English clergyman Thomas Malthus.
0:11:19 > 0:11:23Malthus made a very simple observation about the relationship
0:11:23 > 0:11:27between humans and resources and used it to look into the future.
0:11:29 > 0:11:35He pointed out that "the power of population is indefinitely greater
0:11:35 > 0:11:40"than the power in the Earth to produce subsistence for man."
0:11:40 > 0:11:46Food production can't increase as rapidly as human reproduction.
0:11:46 > 0:11:49Demand will eventually outstrip supply.
0:11:49 > 0:11:54Malthus goes on to say, if we don't control human reproduction voluntarily,
0:11:54 > 0:12:01life could end in misery, which earned him a reputation as a bit of a pessimist.
0:12:01 > 0:12:04But Malthus's principle remains true.
0:12:04 > 0:12:08The productive capacity of the Earth has physical limits
0:12:08 > 0:12:13and those limits will ultimately determine how many human beings it can support.
0:12:20 > 0:12:25To help answer that question, we need to have an idea of what human beings need.
0:12:25 > 0:12:30And the people who calculate this more precisely than most
0:12:30 > 0:12:34are the people who are more interested in leaving the planet than staying on it.
0:12:34 > 0:12:37Astronauts.
0:12:37 > 0:12:41One of the people in charge of the wellbeing of astronauts
0:12:41 > 0:12:45on the International Space Station is Doug Hamilton.
0:12:46 > 0:12:49NASA, we calculate and simulate everything.
0:12:49 > 0:12:53If you are going to plan a rocket launch, you have to know how much
0:12:53 > 0:12:57food and water and equipment you need to bring into space.
0:12:57 > 0:13:01As well as working out how much space the astronauts need,
0:13:01 > 0:13:04Doug and his team have to calculate their daily requirements
0:13:05 > 0:13:07for food, water and breathable air.
0:13:07 > 0:13:13They typically need about 820 grams of oxygen, which is
0:13:13 > 0:13:16just a really large, large balloon, really.
0:13:16 > 0:13:20We need about 4,000 to 5,000 calories of food
0:13:20 > 0:13:24which is about 820 grams dry,
0:13:24 > 0:13:28and they need about 3.52 litres of water,
0:13:28 > 0:13:31of which 2.5 litres is just consumed daily.
0:13:31 > 0:13:35We want them to drink a lot of water - it's very good for them.
0:13:35 > 0:13:40And then we urinate out and put that into our processing system and we make it into drinkable water,
0:13:40 > 0:13:45so you might be drinking the same water molecule hundreds and hundreds of times
0:13:45 > 0:13:48on the space station, because we recycle.
0:13:51 > 0:13:54NASA's calculations are tailored for space,
0:13:54 > 0:13:59but they're the same ingredients each and every one of us needs.
0:14:00 > 0:14:04When you see how hard it is to reproduce
0:14:04 > 0:14:08what Mother Nature does every day for all of us,
0:14:08 > 0:14:11you begin to really appreciate the world that you have.
0:14:15 > 0:14:17Whatever our technological achievements,
0:14:17 > 0:14:23we're still utterly reliant on the natural systems of the Earth for our very survival.
0:14:24 > 0:14:29By and large the planet has provided for the human race, so far.
0:14:29 > 0:14:34As the population has increased, people, through agriculture and industry,
0:14:34 > 0:14:37have exploited those resources ever more effectively.
0:14:37 > 0:14:40But increasingly, we're seeing signs of strain.
0:14:40 > 0:14:43We're reaching the limits of our environment.
0:14:43 > 0:14:48Perhaps most alarmingly with that fundamental ingredient for life - water.
0:14:53 > 0:14:55We call our Earth the Blue Planet
0:14:55 > 0:15:00because about 70% of the Earth's surface is covered in water.
0:15:00 > 0:15:06But most of that is sea - just 2.5% is fresh water.
0:15:06 > 0:15:11And of that tiny fraction, just 1% is available for human use.
0:15:11 > 0:15:14The rest is locked up in mountain glaciers
0:15:14 > 0:15:16and the Earth's polar ice caps.
0:15:16 > 0:15:21But there's another fact we need to understand about water.
0:15:24 > 0:15:28Well, there's no more water on the planet than there was when life first appeared on Earth.
0:15:28 > 0:15:31It changes its distribution.
0:15:31 > 0:15:34There's more water in different parts of the world.
0:15:34 > 0:15:38But its still the same amount of water that's been here always.
0:15:43 > 0:15:49We appropriate over half of all the available fresh water in the world to serve our needs.
0:15:49 > 0:15:52To transform deserts into fields.
0:15:53 > 0:15:56To generate energy from rivers.
0:15:56 > 0:16:01And to build cities in some of the most arid regions on the planet.
0:16:01 > 0:16:06But despite our ingenuity, there are many who struggle to get enough of this basic resource.
0:16:08 > 0:16:13More than a billion people on the planet already lack access to safe, clean, drinking water.
0:16:13 > 0:16:18And we know that things are going to get more difficult as the population continues to grow.
0:16:18 > 0:16:23Within the next 20 years as much as half of the world's population will live in areas of water stress.
0:16:23 > 0:16:28Chronic water shortages are often the result of poor infrastructure,
0:16:28 > 0:16:33politics, poverty, or simply living in an arid part of the world.
0:16:33 > 0:16:37But increasingly the pressures of population are to blame.
0:16:46 > 0:16:51Mexico City is ranked as the eighth-richest city in the world,
0:16:51 > 0:16:56ahead of Moscow, Hong Kong and Washington DC.
0:16:57 > 0:17:00It also benefits from heavy annual rainfall.
0:17:04 > 0:17:08But its water system is buckling under the pressure
0:17:08 > 0:17:11of supplying water to its 20 million inhabitants.
0:17:11 > 0:17:16And every day at least a million people are affected by the shortages.
0:17:20 > 0:17:24Enrique Vazquez is a water truck driver for the government.
0:17:26 > 0:17:31And the number of people relying on this emergency service is growing daily.
0:17:34 > 0:17:40Today he's heading for a poor district in the city's south-west, where he's a regular visitor.
0:17:48 > 0:17:53TRANSLATION: At some time in the future, wars are going to be fought over water, not oil.
0:17:53 > 0:17:56But people don't seem to understand.
0:17:56 > 0:17:59Instead of conserving it, we just waste it.
0:18:04 > 0:18:08The problem is a combination of leaks in the system,
0:18:08 > 0:18:11and back-up reservoirs that are running dry.
0:18:11 > 0:18:15The city authorities predict that these reservoirs
0:18:15 > 0:18:19may be completely emptied within a matter of months.
0:18:27 > 0:18:30- TRANSLATION:- Look - the tap's on but there's no water coming out.
0:18:34 > 0:18:39The people living here have had to adapt their lifestyles to an erratic water supply.
0:18:43 > 0:18:47We only have half a bucket of water to wash ourselves with.
0:18:47 > 0:18:50And we can't flush the toilet until two or three people have used it.
0:18:57 > 0:19:01TRANSLATION: Unfortunately, I think there's going to be water shortages
0:19:01 > 0:19:05all over the world, not just in Mexico City.
0:19:05 > 0:19:09I think everyone needs to take water more seriously.
0:19:09 > 0:19:13The few people who have water should conserve it better,
0:19:13 > 0:19:17or there'll come a time when the shortages are global,
0:19:17 > 0:19:19and there's little left for anyone.
0:19:21 > 0:19:26In Mexico City, shops which sell water to meet people's daily needs
0:19:26 > 0:19:28are becoming ever more common.
0:19:28 > 0:19:34But the water we use at home is only a fraction of the water we actually consume.
0:19:34 > 0:19:39And that's because we use colossal quantities in industry and agriculture.
0:19:41 > 0:19:44We may know where the water out of our tap comes from,
0:19:44 > 0:19:49but we seldom know where the water that went into our can of cola
0:19:49 > 0:19:51or into the shirt we're wearing,
0:19:51 > 0:19:55where those goods were produced and how much water it required,
0:19:55 > 0:19:58what the consequences were for the natural systems
0:19:58 > 0:20:02and local communities that are dependant on that same water.
0:20:02 > 0:20:06So for example the cup of coffee you may have in the morning
0:20:06 > 0:20:08requires on the order of 120 litres
0:20:08 > 0:20:12just to produce the coffee and bring it to your table.
0:20:12 > 0:20:14A can of beer, 150 litres.
0:20:14 > 0:20:19A hamburger, 8,000 litres of water.
0:20:19 > 0:20:23To produce enough water to grow the cotton in my shirt
0:20:23 > 0:20:25is 3,000 litres, as well.
0:20:28 > 0:20:32The impact of human demands on the world's freshwater systems
0:20:32 > 0:20:35are so massive, they can be seen from space.
0:20:37 > 0:20:41The Aral Sea, a freshwater lake in Central Asia,
0:20:41 > 0:20:45once covered 65,000 square kilometres.
0:20:46 > 0:20:50In the last 40 years it has lost 90% of its water,
0:20:50 > 0:20:54the rivers that feed it diverted to irrigate cotton.
0:20:54 > 0:20:57Lake Chad on the southern edge of the Sahara
0:20:57 > 0:21:00has also been drained to a tenth of its former size
0:21:00 > 0:21:05by drought and overuse. Yet 30 million people depend on it.
0:21:07 > 0:21:12It is possible to distil fresh water from the sea.
0:21:12 > 0:21:16And in the last 20 years, more and more countries have turned to desalination.
0:21:20 > 0:21:22But with current technology desalination plants
0:21:22 > 0:21:27are often extremely expensive, use an enormous amount of energy
0:21:27 > 0:21:30and their by-products can be damaging to our seas.
0:21:32 > 0:21:37With groundwater levels declining across the world from North Africa to China,
0:21:37 > 0:21:41Pollution of rivers and wetlands on the increase,
0:21:41 > 0:21:46and already today more than 1.2 billion people living with water scarcity,
0:21:46 > 0:21:52our prospects for providing water to nearly three billion more people do not look good.
0:21:52 > 0:21:57But in many ways, supplying water to people is the least of our worries.
0:21:57 > 0:22:01As we've seen, the lion's share of the water we use goes into agriculture.
0:22:01 > 0:22:05And that means any water shortages we face in the future
0:22:05 > 0:22:09will affect our ability to provide that other staple of life - food.
0:22:13 > 0:22:16When it comes to the world's food supply,
0:22:16 > 0:22:20some of the most accurate information comes from space.
0:22:20 > 0:22:24Geographer Molly Brown monitors food production on Earth
0:22:24 > 0:22:27using data from NASA's satellites.
0:22:27 > 0:22:32This is a ecosystem in Thailand, where they do rice agriculture,
0:22:32 > 0:22:35and it's extraordinarily productive
0:22:35 > 0:22:39and in one of the most highly productive agricultural regions.
0:22:41 > 0:22:45Now she's beginning to see global agriculture hit a natural limit.
0:22:47 > 0:22:51One of the things that all these different landscapes really show us
0:22:51 > 0:22:55is how we're using almost all the land that's available to us
0:22:55 > 0:22:57that's really highly productive,
0:22:57 > 0:23:01that has great agricultural potential. So we know
0:23:01 > 0:23:04that there isn't a lot of extra land.
0:23:04 > 0:23:08I mean, we're using 30 or 40% of the entire land surface.
0:23:09 > 0:23:12As the world's population increases,
0:23:12 > 0:23:17the urgency with which we're going to have to increase the amount of food we produce will increase.
0:23:17 > 0:23:24So we need to double the amount of food that we have available to us, as soon as possible.
0:23:26 > 0:23:29How we're going to do that is through raising productivity,
0:23:29 > 0:23:33because there's really no more land with which to expand to.
0:23:38 > 0:23:42A doubling of productivity sounds ambitious,
0:23:42 > 0:23:45but we've done even better than that in the past.
0:23:45 > 0:23:51In the 20th century, the industrialised nations managed to triple their farming yields
0:23:51 > 0:23:53with the invention of synthetic fertilisers
0:23:53 > 0:23:57and then by the introduction of mechanised processes.
0:24:00 > 0:24:04The less developed parts of the world continued using traditional farming methods
0:24:04 > 0:24:08into the 1960s, until an Iowan farmer
0:24:08 > 0:24:11decided to do something about it.
0:24:11 > 0:24:15Norman Borlaug, who died this year aged 95,
0:24:15 > 0:24:21is credited with saving millions of lives in what's become known as the Green Revolution.
0:24:26 > 0:24:28So he was a very unpretentious man.
0:24:28 > 0:24:33You can see from his office.
0:24:33 > 0:24:36Small but very functional.
0:24:36 > 0:24:39And he had some of his awards on the wall.
0:24:39 > 0:24:43But also, in particular, I always thought this picture
0:24:43 > 0:24:46which he kept on the wall was quite typical of
0:24:46 > 0:24:48the kind of person he was.
0:24:48 > 0:24:51His interactions with the next generation of scientists
0:24:51 > 0:24:56around the world and his enthusiasm for getting out into the field
0:24:56 > 0:24:59and showing people what could be done with the science,
0:24:59 > 0:25:02in improving agricultural productivity.
0:25:02 > 0:25:07Borlaug developed high-yielding, disease-resistant crops
0:25:07 > 0:25:09and taught Indian and Mexican farmers
0:25:09 > 0:25:13how to get the most out of them with modern farming methods.
0:25:17 > 0:25:21The astonishing five-fold increases in yield that they achieved
0:25:21 > 0:25:25allowed many countries to become self-sufficient in food.
0:25:26 > 0:25:30In 1970, Borlaug received the Nobel Peace Prize
0:25:30 > 0:25:34for his work in alleviating world hunger.
0:25:36 > 0:25:40He was able to get his wheat, his new varieties, delivered to India,
0:25:40 > 0:25:43and within a few years, it was really astounding.
0:25:43 > 0:25:45He showed me pictures of the mounds of wheat,
0:25:45 > 0:25:51the surplus that had been produced within a few years of introducing these new varieties.
0:25:51 > 0:25:55And in fact that's the seminal event, that's the Green Revolution.
0:25:58 > 0:26:02Thanks in part to Borlaug, much of the world is now fed,
0:26:02 > 0:26:08but globally we're beginning to see a levelling off of agricultural yields.
0:26:12 > 0:26:15This is leading to a worrying new trend.
0:26:22 > 0:26:24To maintain their own food supplies,
0:26:24 > 0:26:28some of the richest and most powerful countries in the world
0:26:28 > 0:26:33are acquiring large tracts of land from some of the very poorest.
0:26:42 > 0:26:45Olivier De Schutter is a human rights lawyer
0:26:45 > 0:26:49who's been monitoring these land deals for the United Nations.
0:26:50 > 0:26:54Arable land suitable for cultivation is becoming a scarce commodity
0:26:54 > 0:26:57and countries find it more and more difficult
0:26:57 > 0:27:00to produce enough food to feed their populations.
0:27:00 > 0:27:03So they are now scrambling in a global competition
0:27:03 > 0:27:06to achieve food security by buying land abroad.
0:27:07 > 0:27:11International corporations and increasingly governments
0:27:11 > 0:27:14are leasing some of the last remaining areas
0:27:14 > 0:27:16of un-developed farmland in the world.
0:27:16 > 0:27:20Their aim is to introduce intensive farming methods
0:27:20 > 0:27:24and export the food back to their home countries.
0:27:25 > 0:27:27The problem is that in most cases
0:27:27 > 0:27:30these deals are not sufficiently well monitored.
0:27:30 > 0:27:36They are not transparent, and we are not certain that local communities will benefit from these investments.
0:27:38 > 0:27:43These deals are often controversial and shrouded in secrecy.
0:27:43 > 0:27:46But according to local media reports,
0:27:46 > 0:27:49Chinese investors are negotiating land deals
0:27:49 > 0:27:55throughout Africa, as well as with Kazakhstan, Mexico and Brazil.
0:27:55 > 0:27:59Saudi Arabian firms have leased farmland in Sudan.
0:27:59 > 0:28:04And several British investment funds are reported to be raising capital
0:28:04 > 0:28:08to buy farmland in Angola, Malawi and Ukraine.
0:28:08 > 0:28:12Most of the target countries for foreign investors are in Africa,
0:28:12 > 0:28:16some of which already struggle to feed their own people.
0:28:16 > 0:28:19When we see paradoxical situations
0:28:19 > 0:28:23such as foreign investors producing food in Ethiopia,
0:28:23 > 0:28:25shipping this food back to the home country,
0:28:25 > 0:28:28or selling it on the international markets
0:28:28 > 0:28:32when Ethiopia is still a country which is heavily dependent on international food aid.
0:28:32 > 0:28:37So this is a country which is at the same time producing food for export markets
0:28:37 > 0:28:40and depending on international aid in order to feed its population.
0:28:42 > 0:28:48The future is going to be particularly challenging for the countries of sub-Saharan Africa.
0:28:48 > 0:28:51With many of their populations projected to double,
0:28:51 > 0:28:55there's going to be increasing pressure for a limited supply of land.
0:28:57 > 0:29:00There are few nations as acutely aware of
0:29:00 > 0:29:05how destabilising these kinds of pressures can be as Rwanda.
0:29:05 > 0:29:08Our land is not growing
0:29:08 > 0:29:11and yet our population is.
0:29:11 > 0:29:15We estimate that it will be double in 26 years,
0:29:15 > 0:29:19so in 26 years we will probably be 20 million.
0:29:21 > 0:29:25Rwandans consider land a vital resource.
0:29:25 > 0:29:32But they also see it as a resource for primarily their own use,
0:29:32 > 0:29:38for their own security, for their own food security.
0:29:39 > 0:29:46Martin Seturinka grows bananas and maize on three acres of farmland.
0:29:46 > 0:29:51Like 80% of Rwandans, his family subsist on what they can grow.
0:29:54 > 0:29:56Land is an issue all over Rwanda.
0:29:56 > 0:29:59There isn't enough land to go around
0:29:59 > 0:30:03and people find it hard to grow enough food to survive.
0:30:03 > 0:30:08In Rwanda, children inherit land from their parents,
0:30:08 > 0:30:12but in a country where the average family has more than five children,
0:30:12 > 0:30:13that can only mean one thing.
0:30:13 > 0:30:17Smaller parcels of land to live off.
0:30:22 > 0:30:25I don't know what will happen to my children,
0:30:25 > 0:30:28or how they'll cope, I honestly don't.
0:30:28 > 0:30:33It's already impossible for me to provide enough food for them.
0:30:35 > 0:30:36Only God knows.
0:30:41 > 0:30:45Martin is father to 15 children.
0:30:45 > 0:30:47But they aren't all his own.
0:30:47 > 0:30:51Five of them are adopted, orphans whose parents
0:30:51 > 0:30:55were brutally murdered in Rwanda's devastating genocide.
0:31:01 > 0:31:05In 1994, the two major tribes in Rwanda,
0:31:05 > 0:31:09the Hutus and Tutsis, embarked on a mutual slaughter
0:31:09 > 0:31:13that left almost a million dead in just three months.
0:31:19 > 0:31:21Amongst the many causes of that conflict,
0:31:21 > 0:31:25competition for scarce resources was an added pressure.
0:31:28 > 0:31:34Poverty became a mobilising tool, the poor unemployed youth,
0:31:34 > 0:31:37some of them were encouraged to kill their neighbours...
0:31:39 > 0:31:44..with the hope they'd either inherit their piece of land,
0:31:44 > 0:31:47or their house, or their livestock.
0:31:54 > 0:32:01If we cannot grow the economy fast enough to meet this growth,
0:32:01 > 0:32:05and can't slow it down, then there will be increased competition
0:32:05 > 0:32:07for resources which are finite.
0:32:07 > 0:32:13So our forests are likely to go, our swamps will be overused.
0:32:13 > 0:32:17Therefore this will also have an effect on the climate,
0:32:17 > 0:32:21climatic changes which will further exacerbate
0:32:21 > 0:32:23the negative effects of this growth.
0:32:23 > 0:32:29It's a bit of a vicious cycle and we must find a way of breaking it.
0:32:37 > 0:32:41In Rwanda, the government can already foresee the impact
0:32:41 > 0:32:46population growth is likely to have on their immediate environment.
0:32:46 > 0:32:50Across the world, population growth is likely to take
0:32:50 > 0:32:54an even greater toll because of our ever-increasing demands
0:32:54 > 0:32:57for a resource we've come to depend on,
0:32:57 > 0:33:01but which may be causing us the biggest damage of all.
0:33:05 > 0:33:08Of all the resources that humans have harnessed from the Earth,
0:33:08 > 0:33:12the one that has transformed everything is energy.
0:33:12 > 0:33:16Fossil fuels are the remains of plants and animals
0:33:16 > 0:33:18that lived perhaps 350 million years ago
0:33:18 > 0:33:22and later became buried in the Earth's crust.
0:33:22 > 0:33:24With the technologies of the industrial age,
0:33:24 > 0:33:26we liberated this energy
0:33:26 > 0:33:31and used it to get more from nature than had ever been possible before.
0:33:31 > 0:33:33Our favourite fossil fuel is oil.
0:33:33 > 0:33:36Our demand for it increases every year.
0:33:36 > 0:33:41Today we use 85 million barrels a day.
0:33:41 > 0:33:46Oil provides the fertiliser, pesticide and mechanisation that has
0:33:46 > 0:33:51allowed us so far to produce enough food for our expanding population.
0:33:51 > 0:33:55But just as we're realising how much we depend on it,
0:33:55 > 0:33:57it's getting harder to find.
0:34:02 > 0:34:04Houston, Texas.
0:34:04 > 0:34:08One of the richest places in the world,
0:34:08 > 0:34:12thanks to its vast reserves of oil and gas.
0:34:17 > 0:34:21Danny Davis is an independent oil producer.
0:34:24 > 0:34:30This is our office, our base of operations and what we do.
0:34:30 > 0:34:33Our little company sign, which we're very proud of.
0:34:33 > 0:34:37Danny has been drilling oil in Texas since the early 1980s.
0:34:37 > 0:34:40This is a collection of jars of oil from all the wells
0:34:40 > 0:34:43we've found over the years, I guess over the last 15 years.
0:34:43 > 0:34:46One of them I kind of like the most,
0:34:46 > 0:34:49is this one. This was discovered about 30 minutes
0:34:49 > 0:34:51outside of Houston on the Brookshire Dome.
0:34:51 > 0:34:56This came out at 1,000 barrels of oil a day from 2500 feet.
0:34:56 > 0:34:58High gravity sweet crude. It smells great.
0:34:58 > 0:35:01When it comes out its so fresh you can put it on your salad,
0:35:01 > 0:35:03little oil and vinegar, it's good stuff.
0:35:03 > 0:35:06This is why we do it, this is what it's all about,
0:35:06 > 0:35:09it's an exciting business.
0:35:09 > 0:35:14There's a fortune to be made treating these reservoirs.
0:35:14 > 0:35:19These days, oil in Texas is getting harder to find.
0:35:19 > 0:35:23Danny's looking much further afield, to Alaska.
0:35:23 > 0:35:26He's been granted a rare license from the government
0:35:26 > 0:35:30to drill offshore. But before he can get started,
0:35:30 > 0:35:34Danny needs to raise millions of dollars of investment.
0:35:36 > 0:35:39Let me ask you a question, how many years you been doing this,
0:35:39 > 0:35:41about 40 or 50?
0:35:41 > 0:35:46If his plans are successful, the figures are truly staggering.
0:35:46 > 0:35:49You look at a billion of barrels of oil and oil's 70 a barrel
0:35:49 > 0:35:52and you got two billion barrels, in gross numbers,
0:35:52 > 0:35:55200 billion dollars, probably.
0:35:55 > 0:35:57I don't know, I couldn't predict that.
0:35:57 > 0:35:59You can only go on the value today,
0:35:59 > 0:36:01you don't know what it's is going to be tomorrow.
0:36:01 > 0:36:03Yeah, I'll call him and let him know.
0:36:03 > 0:36:06Thanks for everything. All right, guys.
0:36:07 > 0:36:08We'll see y'all soon.
0:36:11 > 0:36:15Danny won't be short of customers for his oil because energy demand
0:36:15 > 0:36:20is predicted to increase by 40% over the next two decades.
0:36:20 > 0:36:24The Alaskan fields may make him a very wealthy man.
0:36:24 > 0:36:27But the fossil fuels that have helped to bring great wealth
0:36:27 > 0:36:33to many nations as well as individuals are proving to be a double-edged sword.
0:36:33 > 0:36:37Not just because of their contribution to climate change.
0:36:37 > 0:36:40What cheap energy has allowed us to do fundamentally
0:36:40 > 0:36:44is to appropriate the Earth's natural systems to serve our needs,
0:36:44 > 0:36:47without paying too much attention to the long-term effects
0:36:47 > 0:36:49on the environment and other species.
0:36:51 > 0:36:54It seems we're just beginning to realise the full impact
0:36:54 > 0:36:59that our industrialisation is having upon the natural world.
0:36:59 > 0:37:03In the oceans we've depleted fish stocks massively.
0:37:03 > 0:37:0610% of the world's coral reefs
0:37:06 > 0:37:09are estimated to be degraded beyond recovery.
0:37:09 > 0:37:15A third of the world's amphibians, a fifth of all mammals and 70%
0:37:15 > 0:37:20of all plants are currently under threat of extinction.
0:37:20 > 0:37:23When it comes to conserving our natural world,
0:37:23 > 0:37:26there are two arguments to contend with.
0:37:26 > 0:37:29On the one hand, there's a sense of our moral obligation,
0:37:29 > 0:37:33as the most intelligent species on the planet, to protect
0:37:33 > 0:37:38the marvellous variety of species that have evolved alongside us.
0:37:38 > 0:37:43On the other, there's self-interest. The more we damage the environment,
0:37:43 > 0:37:46the more we threaten our own survival.
0:37:46 > 0:37:49Perhaps self-interest is the more powerful argument
0:37:49 > 0:37:53because how we treat our environment certainly determines
0:37:53 > 0:37:56how many people the Earth can sustain.
0:37:57 > 0:38:01There's a concept in ecology called "carrying capacity".
0:38:01 > 0:38:04It's a calculation of how large a population
0:38:04 > 0:38:07any given environment can support.
0:38:20 > 0:38:24William Rees is a human ecologist who's taken the concept
0:38:24 > 0:38:28and applied it to ourselves and our environment, the Earth.
0:38:33 > 0:38:35The simple fact of the matter is
0:38:35 > 0:38:38the Earth can accommodate so much consumption.
0:38:38 > 0:38:41You might have ten billion people at one level of living
0:38:41 > 0:38:44and a billion at a more comfortable level of living.
0:38:44 > 0:38:47So carrying capacity is a very flexible idea.
0:38:47 > 0:38:50You simply divide the total productivity of the Earth
0:38:50 > 0:38:52by the number of people and that gives you some idea
0:38:52 > 0:38:54of how many people the Earth can support.
0:38:56 > 0:38:59Rees has estimated what he calls
0:38:59 > 0:39:03the productive bio-capacity of the Earth.
0:39:03 > 0:39:08This is made up of all the food, water and energy produced across
0:39:08 > 0:39:12the world each year, and measured in units called global hectares.
0:39:12 > 0:39:16He's worked out that if we were to share the Earth's
0:39:16 > 0:39:22productive bio-capacity fairly, there'd be two global hectares each.
0:39:22 > 0:39:26But the reality tells a very different story.
0:39:26 > 0:39:31According to Rees's data, most of Africa use little more than
0:39:31 > 0:39:35half of their share of the Earth's productive capacity.
0:39:35 > 0:39:39The average Indian uses less than half.
0:39:39 > 0:39:44The Chinese use their fair allocation of two hectares each.
0:39:44 > 0:39:49But Europeans use much more with the British on average
0:39:49 > 0:39:52using over five global hectares.
0:39:52 > 0:39:57And the average American, using more than four times their fair share.
0:40:01 > 0:40:06So how many people can the Earth sustain?
0:40:06 > 0:40:08Well, according to these calculations,
0:40:08 > 0:40:12if all humans consumed the same as the average Indian does today,
0:40:12 > 0:40:18the Earth could sustain as many as 15 billion people.
0:40:18 > 0:40:22If we consumed as little as the average Rwandan,
0:40:22 > 0:40:25this would go up to 18 billion.
0:40:25 > 0:40:28But our planet can only sustain 2.5 billion people
0:40:28 > 0:40:30living as we do in Britain.
0:40:30 > 0:40:34And only 1.5 billion living in the lifestyle
0:40:34 > 0:40:36of those in the United States.
0:40:36 > 0:40:40But the picture may even be worse than this.
0:40:40 > 0:40:44These figures are based on rates of consumption
0:40:44 > 0:40:48that many think are already unsustainable.
0:40:50 > 0:40:52There's plenty of evidence right now
0:40:52 > 0:40:55that we are already in the state of what we call overshoot.
0:40:55 > 0:41:00Each year the human population at current average levels of consumption,
0:41:00 > 0:41:02which most of us in Europe and North America
0:41:02 > 0:41:05would consider to be inadequate, is already exceeding
0:41:05 > 0:41:07the productive capacity of the planet.
0:41:07 > 0:41:10Not only in terms of its ability to produce,
0:41:10 > 0:41:13but also in terms of its capacity to assimilate our wastes.
0:41:16 > 0:41:20Rees believes that today's population requires the equivalent
0:41:20 > 0:41:25of 1.5 Earths to support our current way of life.
0:41:25 > 0:41:30We're simply living beyond the means of our environment to sustain us.
0:41:32 > 0:41:35To have a state of sustainability where we remain
0:41:35 > 0:41:37within the productive capacity of the planet,
0:41:37 > 0:41:40means that people in industrialised countries
0:41:40 > 0:41:44are going to have to give up consumption of a great deal in order
0:41:44 > 0:41:48to create the ecological space for needed growth in the third world.
0:41:48 > 0:41:50If we don't make those kinds of compromises,
0:41:50 > 0:41:53then we're going to continue to erode the resource base
0:41:53 > 0:41:57of the planet to the point where we all suffer.
0:41:59 > 0:42:03As I see it, humanity needs to reduce its impact on the Earth
0:42:03 > 0:42:07urgently and there are three ways to achieve this.
0:42:07 > 0:42:10We can stop consuming so many resources.
0:42:10 > 0:42:13We can change our technology
0:42:13 > 0:42:17and we can reduce the growth of our population.
0:42:17 > 0:42:20We probably need to do all three.
0:42:21 > 0:42:25For most people, the idea of someone else telling them
0:42:25 > 0:42:28how many children they should have is simply unacceptable.
0:42:28 > 0:42:32So when governments attempt to do exactly that,
0:42:32 > 0:42:34it always causes controversy.
0:42:34 > 0:42:39In 1979, the Chinese government introduced its infamous
0:42:39 > 0:42:43one child policy, changing family life in China forever.
0:42:55 > 0:42:58Families were encouraged to have fewer children,
0:42:58 > 0:43:00those that didn't were fined.
0:43:00 > 0:43:03The policy was a direct response
0:43:03 > 0:43:06to the preceding decades of famine and starvation.
0:43:09 > 0:43:12It's still in place today.
0:43:12 > 0:43:17According to official figures, without the one child policy,
0:43:17 > 0:43:20there'd be 400 million more people in China -
0:43:20 > 0:43:24that's more than the entire population of the USA.
0:43:24 > 0:43:27It's unlikely that other governments could undertake
0:43:27 > 0:43:31such an extreme path without major civil opposition.
0:43:34 > 0:43:37In the 1970s, the Indian government
0:43:37 > 0:43:40also sought to bring down its birth rate.
0:43:40 > 0:43:43To start with, it took a less aggressive path,
0:43:43 > 0:43:46setting up festivals around the country
0:43:46 > 0:43:51where vasectomies were offered in return for small incentives.
0:43:51 > 0:43:53In those days, in those festivals,
0:43:53 > 0:43:57they have done in a week something like 80,000 sterilisations.
0:43:57 > 0:44:00The incentive was some cash,
0:44:00 > 0:44:02some money, nothing much.
0:44:02 > 0:44:06The problem was the festivals were attracting the wrong customers,
0:44:06 > 0:44:09people who already had large families.
0:44:09 > 0:44:14That is the weakness of incentivisation - they could not
0:44:14 > 0:44:17attract the couples with two children,
0:44:17 > 0:44:22they attract couples with five children, six children.
0:44:22 > 0:44:26It's like closing the door after the horse has gone.
0:44:27 > 0:44:33But in some areas, politicians took the sterilisation drive a step too far.
0:44:33 > 0:44:39In 1977, when Indira Gandhi was introduced the emergency programme.
0:44:41 > 0:44:42What they did,
0:44:42 > 0:44:47the punishment for every crime in those days were sterilisation.
0:44:47 > 0:44:51For example, if a person travels in a train,
0:44:51 > 0:44:54he has no ticket,
0:44:54 > 0:44:57what is the punishment? He was taken for sterilisation.
0:45:04 > 0:45:10In 1977 alone, around eight million people were sterilised.
0:45:10 > 0:45:12And the public outcry was so great
0:45:12 > 0:45:15that it helped to bring down the government.
0:45:15 > 0:45:19Hopefully these kind of coercive policies are a thing of the past.
0:45:19 > 0:45:23Because we're beginning to realise that birth rates fall,
0:45:23 > 0:45:25provided the conditions are right.
0:45:34 > 0:45:40In the south-west of India lies the long narrow coastal state of Kerala.
0:45:40 > 0:45:44Most of its 32 million inhabitants live off the land and the ocean,
0:45:44 > 0:45:50a rich tropical ecosystem watered by two monsoons a year.
0:45:50 > 0:45:53It's also one of India's most crowded states.
0:45:57 > 0:46:03But the population is stable because nearly everybody has small families.
0:46:09 > 0:46:12How many of you have only one child in the house? Raise your hands.
0:46:12 > 0:46:14Only one. You are the only one in the house.
0:46:14 > 0:46:17Only one? Only one?
0:46:17 > 0:46:20I think today almost 30 to 40% of couples
0:46:20 > 0:46:23in Kerala have just one child.
0:46:23 > 0:46:26How many of you have two in the house two? Two.
0:46:26 > 0:46:28Two in the house.
0:46:28 > 0:46:33Today on average, Kerala women produce only 1.5 children.
0:46:33 > 0:46:35How many of you three in the house?
0:46:35 > 0:46:37Three, three, three.
0:46:37 > 0:46:39No problem, brother or sister?
0:46:39 > 0:46:44- Two brothers.- They wanted a girl. That's why they got three. Otherwise no.
0:46:44 > 0:46:48You will rarely see a couple with now three children, very rarely.
0:46:56 > 0:46:59At the root of it all is education.
0:46:59 > 0:47:03Thanks to a long tradition of compulsory schooling for boys
0:47:03 > 0:47:08and girls, Kerala has one of the highest literacy rates in the world.
0:47:11 > 0:47:14Even too-young children are coming to school.
0:47:16 > 0:47:20See, they are carrying bags bigger than them.
0:47:24 > 0:47:27Where women are well-educated,
0:47:27 > 0:47:30they tend to choose to have smaller families.
0:47:33 > 0:47:36When all girls goes to school,
0:47:36 > 0:47:39automatically they will marry very late.
0:47:39 > 0:47:45For example, today in Kerala average woman marries at the age of 28.
0:47:45 > 0:47:49Whereas a state like Uttar Pradesh, Rajasthan, Bihar,
0:47:49 > 0:47:52the girl marries at the age of 18.
0:47:52 > 0:47:57So, at 28, these women in Uttar Pradesh and Bihar
0:47:57 > 0:48:01have already four children, where Kerala girl is even not married.
0:48:01 > 0:48:03How many children do you want to have?
0:48:03 > 0:48:05ALL: One.
0:48:13 > 0:48:17What Kerala shows is that you don't need aggressive policies
0:48:17 > 0:48:21or government incentives for birth rates to fall.
0:48:21 > 0:48:25Everywhere in the world where women have access to education,
0:48:25 > 0:48:27and have the freedom to run their own lives,
0:48:27 > 0:48:29on the whole, they and their partners
0:48:29 > 0:48:33have been choosing to have smaller families than their parents did.
0:48:33 > 0:48:37But reducing birth rates is very difficult to achieve
0:48:37 > 0:48:43without a simple piece of medical technology - contraception.
0:48:43 > 0:48:48We can think of modern contraception as a crucial technology
0:48:48 > 0:48:52for the sustainability of the planet because it's the element
0:48:52 > 0:48:56that has allowed the populations of many developing countries
0:48:56 > 0:48:59to reduce their fertility as rapidly as they have done.
0:49:04 > 0:49:11Despite a recent history that makes population a particularly delicate subject in Rwanda,
0:49:11 > 0:49:14the government here is one of the few in Africa
0:49:14 > 0:49:18to have made universal access to contraception
0:49:18 > 0:49:21a national priority in recent years.
0:49:21 > 0:49:26Console Mukanyarwaya is one of hundreds of family planning officers
0:49:26 > 0:49:30who give contraceptive advice to local communities.
0:49:32 > 0:49:36Since the year 2000, family planning education
0:49:36 > 0:49:39has been provided for everyone in the country.
0:49:42 > 0:49:47Rwandans understand that while it's wonderful to have children,
0:49:47 > 0:49:50you've got to be able to look after them as well as you can.
0:49:50 > 0:49:53We try to get people who use contraception
0:49:53 > 0:49:56to teach their neighbours so they can see for themselves
0:49:56 > 0:49:59the advantages of having fewer children.
0:50:02 > 0:50:04Since it has become freely available,
0:50:04 > 0:50:09the uptake for contraception has been huge in Rwanda, with many women
0:50:09 > 0:50:13opting for injections or even five-year hormone implants.
0:50:15 > 0:50:19While Rwanda is addressing its population growth,
0:50:19 > 0:50:21it's estimated that a quarter of married women
0:50:21 > 0:50:26in sub-Saharan Africa still don't have any access to contraception.
0:50:26 > 0:50:31And across the world, over 80 million births are unplanned.
0:50:33 > 0:50:34In my view it's a basic human right,
0:50:34 > 0:50:37that everyone should have access to contraception.
0:50:37 > 0:50:41All the evidence is that people take advantage of this
0:50:41 > 0:50:46once they have the possibility and they reduce their fertility.
0:50:46 > 0:50:50If that happens, then, amongst other things, the world's population
0:50:50 > 0:50:54growth will eventually level out at a lower rather than a higher number.
0:50:54 > 0:50:55And that's a good thing.
0:51:04 > 0:51:08When it comes to other ways of reducing human impact on the Earth,
0:51:08 > 0:51:11there are a few glimmers of hope emerging.
0:51:11 > 0:51:14Governments across the world are beginning to recognise
0:51:14 > 0:51:18that the life-support services provided by our ecosystems
0:51:18 > 0:51:22are in need of repair, and they're doing something about it.
0:51:26 > 0:51:29Often it takes individuals with vision
0:51:29 > 0:51:31to lead the process of change.
0:51:31 > 0:51:36Valente Souza is an urban planner and a committed environmentalist
0:51:36 > 0:51:39with a lot of responsibility.
0:51:39 > 0:51:43The government of Mexico City have employed him to find
0:51:43 > 0:51:46a sustainable solution to their water shortages.
0:51:46 > 0:51:50And he's convinced the local ecosystem holds the answers.
0:51:50 > 0:51:54The solution is at hand and the solution is called the rain.
0:51:54 > 0:51:57Because we are at the top of the mountain
0:51:57 > 0:52:00and the only source of water is rain, not rivers.
0:52:00 > 0:52:04We have to re-establish what we call the hydrological cycle.
0:52:07 > 0:52:12This cycle relies on ancient forests that used to surround the city.
0:52:12 > 0:52:15But as the city's grown they've all but disappeared.
0:52:15 > 0:52:19And here you can see a water truck coming up.
0:52:28 > 0:52:33Souza's mission is to protect the remaining forests.
0:52:36 > 0:52:39Part of that is building walls to prevent soil erosion.
0:52:54 > 0:53:01Mexico City is surrounded by a rock like this with a forest on top.
0:53:01 > 0:53:05It rains, the soil prevents it from running fast.
0:53:05 > 0:53:09It trickles inside all of these holes and the water comes out here,
0:53:09 > 0:53:11on the valley of Mexico.
0:53:11 > 0:53:15And that's how Mexico City gets its water from, from this rock,
0:53:15 > 0:53:18which is like a doughnut around it.
0:53:18 > 0:53:24For this natural process to work, it relies on a rich layer of topsoil.
0:53:24 > 0:53:30My hand is moist, because this is saturated with water.
0:53:30 > 0:53:33If, when it rains, this gets saturated with water then the rocks
0:53:33 > 0:53:39have the time to get saturated with water, because they have...
0:53:39 > 0:53:43They're slower at having water inside, so you need this.
0:53:44 > 0:53:50The only way for us to have water down there, is to catch it up here.
0:53:50 > 0:53:52If we lose the forest, we lose the water.
0:53:52 > 0:53:56Souza is drawing up plans to conserve,
0:53:56 > 0:53:58protect and replant the forests,
0:53:58 > 0:54:02working with the local communities who own them.
0:54:02 > 0:54:05These people are the owners of this particular forest.
0:54:05 > 0:54:09It's private property. And instead of being farmers
0:54:09 > 0:54:13cultivating corn, they cultivate trees.
0:54:13 > 0:54:17They call this a water forest.
0:54:19 > 0:54:24We're responsible for the forest. We must look after it.
0:54:24 > 0:54:28We make sure there's no illegal developments or logging.
0:54:28 > 0:54:31No pollution, no rubbish.
0:54:31 > 0:54:35It's both our role and our duty.
0:54:38 > 0:54:43Even in the heart of a vast urban metropolis like Mexico City,
0:54:43 > 0:54:48the intimate relationship between humans and the natural world endures.
0:54:55 > 0:54:58It seems to me that an understanding
0:54:58 > 0:55:01of the natural world is crucial for all of us.
0:55:05 > 0:55:09After all, we depend upon it for our food, for the air we breathe,
0:55:09 > 0:55:12and some would say, for our very sanity.
0:55:15 > 0:55:19It's a relationship that we're stretching to breaking point
0:55:19 > 0:55:21as we continue to grow in numbers.
0:55:29 > 0:55:31Within the course of this programme,
0:55:31 > 0:55:35the human population has increased by another 9,000 people.
0:55:38 > 0:55:43Each one of them will be making their own demands on the Earth.
0:55:43 > 0:55:49We have to be using water and all of the other natural resources
0:55:49 > 0:55:51in a much more sustainable fashion.
0:55:51 > 0:55:56We have to quit wasting so much, we have to quit polluting so much,
0:55:56 > 0:56:01and if we do those things and if we put the science and the technology
0:56:01 > 0:56:05that's already available to us into play, into implementation today,
0:56:05 > 0:56:10then we have a chance to make it into the next
0:56:10 > 0:56:1330 or 40 or 50 years, and into a population of eight or nine billion.
0:56:13 > 0:56:16But if we don't start doing those things immediately,
0:56:16 > 0:56:17we don't stand a chance.
0:56:20 > 0:56:25If current trends unfold the way some scientists think they will,
0:56:25 > 0:56:28it will be a very different planet by the middle of this century.
0:56:28 > 0:56:31The temperature may be up to two or three degrees warmer.
0:56:31 > 0:56:34If that's the case, food and most other resources
0:56:34 > 0:56:35are going to be scarcer.
0:56:35 > 0:56:37There will be eight or nine billion people here
0:56:37 > 0:56:40and the question our children are going to ask us is,
0:56:40 > 0:56:43"If you saw this coming, why weren't you able to do anything about it?"
0:56:48 > 0:56:53I'm very aware that this film could be seen as bleak and depressing.
0:56:53 > 0:56:59An increasing population with an ever-decreasing supply of resources.
0:56:59 > 0:57:03But humans have capabilities that animals don't -
0:57:03 > 0:57:07to think rationally, to study and to plan ahead.
0:57:07 > 0:57:11The number of people on the planet in the future depends on
0:57:11 > 0:57:15the personal decisions we each make about how many children we have.
0:57:15 > 0:57:18Even setting aside the moral responsibility we have
0:57:18 > 0:57:23to protect other species, if we continue to damage our ecosystems,
0:57:23 > 0:57:24we damage ourselves.
0:57:24 > 0:57:27It's clear that we'll have to change the way we live
0:57:27 > 0:57:29and use our resources.
0:57:29 > 0:57:33We're at a crossroads where we can choose
0:57:33 > 0:57:36to cooperate or carry on regardless.
0:57:36 > 0:57:39Can our intelligence save us?
0:57:39 > 0:57:41I hope so.
0:57:59 > 0:58:01Subtitles by Red Bee Media
0:58:01 > 0:58:03E-mail subtitling@bbc.co.uk