This vast salt pan in Africa is all that remains of an ancient lake.
It's totally waterless and oven-hot.
Few places on the land are more hostile to life.
A few tracks cross it, made by animals searching unsuccessfully for water.
But very occasionally , this whole landscape is transformed.
A huge deluge drenches the salt pan.
Triggered by some unknown signal, flocks of lesser flamingos arrive from thousands of kilometers away.
The algae that the flamingos feed on have lain dormant as spores in the dust.
But most importantly, the birds are here to breed.
Perfect conditions might occur only once in a decade.
The birds nest on an island far from the shore.
They build mounds of mud that raise up their eggs, and so keep them just marginally cooler than they would be at ground level.
The water surrounding the island is so salty, that predators do not venture into it.
So the nests are safe.
Thirty days later, thousands of chicks start to hatch.
But there is no shelter from the scorching sun. The water that once surrounded their island, protecting them, The last to hatch step out into a desperately harsh world. has now dried up altogether. Somehow or other, the growing chicks must find fresh water to drink. They cannot yet fly, so they must walk, guided by some of the adults. They may have to trek for 50 kilometers. Some... cannot keep up. The salt has solidified around their legs. Most of the chicks, in spite of everything, and having walked for days, eventually reach fresh water. It is the end of a long journey... but only the first of the trials that will be imposed on these flamingos, by the irregularity of the rains. If rainfall is more predictable and certain, then life can flourish more richly,, both in numbers and variety.
这个位于非洲的巨大盐田,是古代湖泊的遗迹, 完全没有水，热锅一般滚烫,.是生存最不易的地区之一. 其中有些动物的足迹,来自徒劳寻找水源的动物. 但是这样的地貌偶尔会改变.大量的水淹没了盐田。
In places where rains fall abundantly throughout the year, forests grow, and in the warmth of the tropics, they support an unparalleled richness of life.
Half of all the species of land-living animals，live in these stable worlds.
The sheer diversity is breathtaking.
We still have not catalogued all the species that live in the tropical forests.
The relationships between them all are multitudinous and complex.
Plants often depend on animals to pollinate their flowers. And these intimate connections are just as important as the great global ones.
These are traps. Flowers shaped like buckets, produced by an orchid. Each red bucket is filled with an oily liquid that drips from above.
Male orchid bees need a rich perfume with which to impress their females, and the orchids provide it.
But the bucket is slippery, and the liquid into which the bee has fallen is sticky.
The only way to get out is through a narrow tunnel.
As it emerges, the bee is gripped tight.
And that gives enough time for the plant to glue pollen sacs on the bee's back.
So the orchid has its pollen taken to another plant... and the bee is rewarded with a perfume, with which, when it recovers its strength, it can woo a female
At the furthest polar extremes, lie the frozen wildernesses of Antarctica and the Arctic.
Though they may seem remote to many of us, the stability of these icy wastes is crucial to all life on the planet.
But in just 70 years ,things have changed at a frightening pace.
The polar regions are warming fastert han any other part of the planet.,and the sea ice ,on which all life here depends, is disappearing.
specialize in hunting seals out on the frozen ocean.
But that world is now, literally, melting beneath their feet.
The sea ice breaks up every year, but now this is happening earlier, and the bears' limited hunting season is getting shorter.
This is already having a profound impact.
Cubs are growing up under weight,which reduces their chances of survival.
Within the lifetime of these cubs, the Arctic in summer could be largely free of sea ice.
It's not just the sea ice that is vanishing.
The ice that lies on land is also changing fast.
This is Greenland, a vast expanse of ice one-fifth the size of the United States.
This glacial ice, together with the sea ice, protects our planet by reflecting solar radiation away from the surface, and so preventing the Earth from overheating .But the Arctic is warming dramatically
The leading edge of the Store Glacier may appear to be motionless, but glaciers can move at up to 45 meters a day.
Where this one meets the sea ,it towers 100 meters above the water, and continues downward for another 400 meters, beneath the surface.
Over the last 20 years ,Greenland has been losing ice.
And the rate of loss is accelerating.
These massive icefalls from the top of the glacier, are just the beginnings of a far greater event.
A stretch of the front face of the glacier over a kilometer long is starting to break away.
From 400 meters beneath the surface, the hidden ice is surging upwards.
The breakaway of an iceberg the size of a skyscraper generates a colossal tidal wave.
Within 20 minutes,75 million tons of ice break free. Glaciers have always released ice into the ocean, but now this is happening nearly twice as fast as it did ten years ago.
Around the world, ice is now feeding vast amounts of fresh water into the sea, raising sea levels, changing salinity, and disrupting ocean currents.
Without the Humboldt Current, the coast of Peru would fall silent. The seabird spectacle would be no more.
All across our planet, crucial connections are being disrupted.
The stability that we and all life relies upon is being lost.
What we do in the next 20 years will determine the future for all life on Earth.