What is biodiversity?

The term biodiversity is a shortening of biological diversity and according to the Convention on Biological Diversity (CBD) means ''the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.''

The CBD was created by the United Nations Environment Programme and opened for signatures at the Rio Earth Summit in June 1992, by the time signatures were closed in December 1993 168 countries had signed up to its three main aims: the conservation of biological diversity, the sustainable use of its components, and the fair and equitable sharing of the benefits from the use of genetic resources. There are now 193 signatories.

Although around 1.75 million species have been categorised by science the true number of species on the planet is recognised to be much higher than this, many of them tiny organisms which may never be discovered by science.

Estimates as to how many species there range from 3 million to 100 million with the CBD placing the best estimate at around 13 million species.

New species are being discovered all the time: the 1992 Global Biodiversity Strategy said: ''Surprisingly, scientists have a better understanding of how many stars there are in the galaxy than how many species there are on Earth.''

One of the problems in properly estimating the number of species with which we co-exist is the historically ad-hoc nature of much scientific research, there is no central collecting or regulating body and no single database of just what has been discovered and documented.

Biodiversity extends down to the genetic level, with varieties of plants and breeds of animals qualifying as unique blocks in the intricate structures that make up the planet's biological diversity.

It is also taken to refer to the variety of ecosystems or habitats on Earth: from ocean to desert, lake to farmland.

What does biodiversity mean to us?

As humans we often see ourselves as sitting at the top of an evolutionary pyramid and somehow removed from the rest of 'nature'. However, while we have, to a degree, insulated ourselves from natural processes, humans are still massively dependent on the almost unimaginably complex natural systems around us. Forests for example are vital in protecting us from flooding and in helping us get clean drinking water. And, because the natural world is the product of millions of years of evolution and development, it is an incredibly complex system and we have little idea of what the effect of humans on biodiversity - through a massively increased rate of extinction thought to be at the very least 100 times greater than the natural rate - will have. For example, a December 2010 study found that declining biodiversity was increasing rates of infectious disease in humans as so-called 'buffer species' vanish and pathogens look for new victims and find us. Reference.

So much of what we live on - food, industrial materials and medicines for example - comes from the natural world that the United Nations Environment Programme has put a price on failing to preserve biodiversity: and it's between -1.2 and 2.8 trillion a year. NHM - Why conserve biodiversity?

For example, the recent declines in honey bee populations related to colony collapse disorder have caused great concern. FAS - Honey bee collapse disorder report.

While we've mechanised much of our agriculture, we still rely on these little workers to pollinate many of the crops on which we rely: a 2000 study put the value of honey bee pollination to United States agriculture at $14 billion-a-year.

Selective breeding in agriculture has led us to rely on fewer and fewer breeds of plants and animals for our food. Such a narrow range of productive breeds means a greater vulnerability to diseases and pests. Such was the concern at the rate at which crops were vanishing that seed vault was established under a frozen Norwegian Arctic mountain to keep 'back up copies' of thousands of threatened agricultural plant species.

While the fact that a smaller gene pool is of itself a bad thing for the future of life on the planet might be taken for granted, it is not an idea that has been unchallenged. In March 2011, scientists led by Professor Emmett Duffy of the Virginia Institute of Marine Science tried to prove the case conclusively. Their research, Duffy said: ''should be the final nail in the coffin of that controversy. It's the most rigorous and comprehensive analysis yet, and it clearly shows that extinction of plant species compromises the productivity that supports Earth's ecosystems.''

What is happening to biodiversity?

The reasons why biodiversity has become such a buzz word - migrating from the green fringes to the mainstream - is because biodiversity has never been more threatened.

And, it's almost all down to us in the form of rising population, habitat loss, over-exploitation of natural resources, pollution, introduction of new invasive species (often with the best of intentions) and, increasingly climate change. Quebec Biodiversity Website - Impacts on biodiversity.

While, as we have seen it's impossible to even know how many species there are on the planet there is little disagreement that species are now vanishing at a rate unparalleled in history outside previous catastrophic mass extinctions caused by such cataclysms as asteroid impacts and the onset of ice ages. Sixth mass extinction.

The CBD was an attempt to take concerted international action on biodiversity. However, so far its success has been limited. The Conventions aimed, by 2010, to ''achieve, by 2010, a significant reduction of the current rate of biodiversity loss at the local, national and regional levels, as a contribution to poverty alleviation and to the benefit of all life on Earth.''

This target has been missed and gains made seem small when set against the appalling destruction of the variety of life, for example, 31 species of birds were said to have been saved by conservation work.

What can you do about biodiversity?

It may seem an impossible task and a lost battle but how we live our lives can affect biodiversity and the more individuals change their lives the more they have a political mass and therefore a voice.

Lobby your elected representatives to vote for legislation that protects biodiversity. If your government is a signatory to the CBD they should be taking action. For example, the United Kingdom Government has a biodiversity action plan which targets 65 habitats and 1,150 species for conservation action.

If you have spare money to donate then look at ecological and conservation charities which are working to protect habitats and species - there are plenty of them because so much is threatened.

Of course, by living as sustainably as possible we can reduce the impact we have on biodiversity; in the West we have great power as consumers to choose products which are produced sustainably.

You can even create your own little bit of biodiversity if you have a plot of land on which to garden. Make your garden a habitat for wildlife, perhaps consider using the principles of permaculture, a system of gardening which values diversity, water conservation natural predators and aims to mimic natural forest habitats.