BBC State of the Planet – Is there a crisis
We live in extraordinary times, we’re surrounded by more species of animals and plants than have probably existed at any one time in the history of the earth. For nearly 50 years I’ve been lucky enough to spend my time travelling around the earth documenting those animals and plants but it is now increasingly apparent that one species, our own, has developed a unique ability of so altering its surroundings that it can destroy whole species indeed whole environments.
How great is the damage we are actually doing to the world? Why is it that what we do has such a destructive effect and how can we change what we do in order to ensure that our children and grandchildren inherit as wonderful and as varied a world as we were lucky enough to do. I'll be putting those questions to some of the worlds leading scientists in order to discover the very important answers. I will be looking for clues all over the world, some can be found on the savannahs of Africa others are to be sought under the sea, we will visit our own past and consider our future and scientists will talk about their own most recent research in order for us to understand the truth about the current state of our planet. First we have to establish the facts about the scale of the damage we have done to the earth so far.
40 years ago our curiosity about the worlds beyond our planet lead to one of the most stupendous achievements in human history “we have ignition, sequence time, 5, 4, 3, 2, 1 we have lift off.” Paradoxically sending a rocket towards the moon made us aware in a radical way of the true nature of the world it left behind. For most of human history our world had seemed vast and its resources infinite but those men in space saw something different “that is the most beautiful sight, what a view, its absolutely unreal, I have never seen… all I can say is its spectacular”
The astronauts view made us realize more vividly that ever before that the earth is limited in both its space and its resources. From that it follows that there will also be a limit on the amount of life our planet can hold. Living creatures on this planet have always had to endure natural catastrophe and change yet now there is a greater variety of life on earth that there has ever been so change and damage are not necessarily destructive to life as a whole and the view from space showed us why. Its because such damage even on a scale that seems disastrous for those of us in the midst of it is usually local in extent. Indeed, we now realize that such change is the spur that has created life’s richness by presenting new opportunities and challenges to which animals and plants have responded. Life in fact can recover from or adapt to even very great damage but today the damage inflicted by humanity is global and it is taking place at a speed that is without precedent in the whole three and a half billion years of the earth history.
To understand the scale of our impact on the rest of life we have to discover just how great the diversity of life really is. For the past 500 years scientists and explorers have travelled the world cataloguing its natural wonders. We can still see the biggest creature that has ever lived, the blue whale, and the simplest, microscopic bacteria. On land, in the air and under the sea we have discovered an astonishing variety of life forms. That work is still going on giving us a better understanding of this astonishing variety of life, this biodiversity. So how many different kinds of living things are there? Biologist, Sir Robert May has made a special study of this question. Amazingly we don’t even know how many distinct species have been named and recorded, for the major groups like the birds and mammals, the furies and the featheries, we really do know but for most groups they are on scattered records in different museums not yet co-ordinated into one computer base. Best guess would be about one and a half million different plants, animals, fungi, algae. This listing and cataloguing of the natural world has occupied the lives of many experts and still does. A total of one and a half million species might seem to suggest that we have discovered the majority of life forms on the planet, but that is not so, again and again new discoveries make us aware of just how limited our knowledge really is. No where demonstrates this better than the Savannah grasslands of east Africa. In this environment as in many others it is the big mammals that have captured out attention. They have become so famous owing to books television programs and safari holidays that you might well think that they represent the majority of the animals here. The scale of biodiversity on the African grasslands is a bit deceptive if you go out during the day you are probably looking for spectacular animals like these elephants. You will also see a few smaller things like butterflies and beetles and bugs but the overwhelming impression you have of sheer mass of life is of herds of just a few kinds of big animals. The truth as research has recently shown is quite different. For evidence of that just look in the grass. This is a column of driver ants there ferocity so great and their appetite so huge that they have given rise to all kinds of legends, stories about human beings and horses stumbling into their paths and being striped to skeletons within minutes. These are perhaps a little exaggerated but non the less the appetite of these ants is so huge that they will attack anything that cant get out of their way. They prey mainly on other small animals and move across the grasslands in columns that may contain 20 million individuals. So many ants need vast quantities of prey, so their abundance is living proof that the savannas team with smaller life. When scientists recently began to study these smaller creatures. They found that 50% of the insects they were seeing were new to science. Simple calculations suggest that driver ants alone consume more animal matter per year on the grasslands than all the famous big predators put together. The reason why it is difficult to appreciate the scale of biodiversity on the savannahs is that many of the creatures that live here are both nocturnal and very very small. You get some impression of what they are if you come out at night with a lamp like this. But to get an idea of the full range of those creatures you have to use a light of a very special kind like this one. The bulb that is illuminating this sheet produces a high proportion of ultra violet light and many night flying insets find that absolutely irresistible. There are moths, small ones, big ones, here’s a kind of silk moth, beetles, more moths a mantis, a great fat sausage fly, an ant lion lots of tiny little insects I can hardly see what they are oh and mosquitoes. Recent work has shown that there is a far greater variety of insect life on the savannahs than was previously thought. There may not be as many species as are found in a tropical rainforest but in terms of sheer quantity the savannahs are their equal.
It is in the famously rich rainforests of South America that research first revealed the scale of our ignorance. If you walk slowly and look carefully in a rainforest like this one in Ecuador you can find all kinds of small interesting creatures and that is how the first explorers and naturalists worked and it is still possible to find new species that way. I picked up this little stick insect from over there and in order to discover whether it is a new species or not I will have to show it to an expert in stick insects and if he could not match it exactly then he would describe it, give it a new name and I would have discovered a new species. However, I can only search an area from the ground to a couple of feet above my head but the trees here grow to over 100 feet tall. What might be up there? Well birds and monkeys because I can see them from down here but what else might there be? Until very recently that was a matter of pure speculation but then Professor Terry Erwin invented a way of finding out. He decided that in order to discover what actually lived in a canopy of a single tree or even a single branch he had to use a machine known as an insecticide fogger. This was originally designed for mosquito control but it can be used to sample other insect equally well. When we first started fogging in Peru the results were just absolutely fantastic, we just never imagined we were going to get so much. The fog, harmless to anything but insects drifts up into the canopy and the insects drop down. The results of Terry Erwin’s early work dramatically altered our estimates of how many animals there might be on this planet. This might seem a quite drastic way of discovering what lives in the trees, however as well as providing information that is important for conservation this work has also shown that insects reproduce so fast here that within four months of a tree being fogged insects living in it had returned to their previous numbers. From all of the studies I have made over the past 25 years and the little bit that we have been able to analyze in the laboratory it seems that at least 80% of the species that we are getting out of the canopy are new species, new to science and the reason that’s true is because the average size of a beetle is only 3 mm long and so the small stuff hasn’t been studied. And its not just small things in rainforests that are still being discovered. We are still finding things even among the primates, among the mammals, our closest relatives. There are about half a dozen new species of primate that have turned up this decade, small marmoset things. It really underlines what we don’t know. Most of those small primates were found in the Amazon rainforest. Until very recently European explorers could only penetrate any distance into these vast forests by travelling up the rivers. Now however, using powerful machinery roads have been cut though the forests that enable scientists to reach even the least known areas in their search for biological gold, new species. And it is here that they discovered new Marmosets. One way of enticing a primate to show itself is to play back the calls of a closely related species. This can trick it in to thinking that its territory has been invaded by rivals so it may emerge from the forest to investigate. In 1992 this technique revealed a new species of marmoset in this area of Southern Brazil. Since that discovery no one has been back again to look for it and until now it has never been filmed. This kind of waiting game can go on for weeks or months usually without success. But there it is, the call of a new species. This is the black faced marmoset. We have no idea how this animal lives or what kind of social interactions take place in its groups. It has yet to be studied. And as quickly as they appeared the black faced marmosets melt back again into the forest. It is not just on land that the scale of recent discoveries have amazed scientist, the oceans too have been found to contain a far greater diversity of life than was previously thought. The sea covers two thirds of the planet. In some parts it is filled with a huge range of species. The famous coral reefs which occupy a tiny fraction of the oceans are probably its best known most closely studied habitat. Would it be fair to suggest that here at least we have discover most of its inhabitants? Silvia Earle is an expert in marine biology. Just as with what we have begun to understand about rainforests that there are thousands perhaps millions of species that have yet to be discovered, described or even named, so it is with coral reef systems that are enormously complex and diverse but diverse on a scale that exceeds rainforest. If so much remains to be discovered even about coral reefs which occupy the most shallow and accessible parts of the sea what about the rest of it. The average depth is two and a half miles. The depth where the titanic rests, the maximum depth is seven miles and we are still nibbling around the surface. Scuba divers go to 100-150 feet/ 50m or so. We have a few submersibles that can go down to half the oceans depth and one that has been to full ocean depth once but most of the ocean remains a mystery. What does this tell us about the scale of discoveries still to be made in the sea? The greatest era of discovery is just begun, with the oceans less than 5% have really been looked at. Mapping has been done, we know where the valleys are, where the mountains and plains and so on but who lives in the sea? What do we really know of how the natural systems actually function? We are just beginning to understand the magnitude of our ignorance. How little we know has been brought home to us in research in the deep ocean where conditions are so severe that it was once thought that no life of any kind could possibly exist. In fact there are great numbers of creatures in these ocean depths. Some recently discovered are so strange that it can be difficult to see any relationship to organisms that live in shallower water.
Even in the best known environments there are still discoveries to be made. Surprisingly the greatest may come from underground. The top most layer of the land in many places is of course soil. This is crucial because quite simple it is what most plants grow on and it is vital to us as we plant our crops in it. We might think that it is just dead matter with a few worms in it but actually it is full of the most extraordinary creatures. Beneath the surface of the soil the abundance of life is breath taking. In this small patch just in front of me there could well be 2000 different species a quarter of a million different individuals. Most of them of course are very small. Some are microscopic but on their own scale the drama of their worlds is just as great as you can find on the plains of East Africa or the rainforests of South America. Here there are predators and prey just a few millimetres long with their own complex systems of attack and defence.