Biodiversity holds the key to humans' future

G Magazine



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Around eight trillion tonnes of water evaporate from the Amazon Rainforest each year. This mist condenses as clouds which rain down on South America, underpinning food and energy security for hundreds of millions of people.

The rain drains off the basin into the mighty Amazon River, where up to 20% of the world's entire freshwater run-off from the continents rushes out into the Atlantic. The water that rises from these forests influences atmospheric cycles that pervade the planet.

"The beef and soy ranches of Latin America, as well as the hydropower dams that keep the lights on, need that rain," says Andrew Mitchell an academic at Oxford University in England and the director of the Global Canopy Programme, an alliance of rainforest research organisations.

"Rich and diverse tropical forests are the best ones for providing large-scale ecosystem services to humanity... Forests also reduce land surface temperatures by three to five degrees Celsius. They are the air conditioning units of the planet."

You may not realise it, but biodiversity is essential to the priceless functions that ecosystems - such as the Amazon, which is home to 20% of all species - provide to human civilisation, says Mitchell.

"If you have a monoculture you will not get the same ecosystem services as a multiple-species forest. Carbon, water and energy cycles are all really important and biodiversity drives all of them."

Closer to home, the tropical rivers of northern Australia contain approximately 70% of the nation's freshwater resources, and are valued for ecosystem services that support agriculture and tourism and include high quality of rivers for recreational fishing and waterholes which are important to Aboriginal people.

"High levels of species diversity are often correlated with healthy ecosystem function, while degraded ecosystems, with lower diversity, have poor function," says Brad Murray an ecologist at the University of Technology in Sydney.

"Then you don't get all the benefits from nature that you might, such as air and water purification and nutrient cycling... it costs much, much more for us to replace these natural ecosystem functions with human-made means. So it's in our best interests to look after that biodiversity."

An intricate web

Biodiversity, short for biological diversity, is made up of the diversity within species, between species and among ecosystems. Though less than two million species have been described, experts think that Earth may be home to a total of between five and 30 million.

This intricate web of forms has evolved over billions of years and when species are lost, it can be millions of years before something else evolves to replace them.

To flag up the vital role of this rich natural heritage, the UN has christened 2010 the International Year of Biodiversity (IYB), an opportunity to "reflect on our achievements to safeguard biodiversity and focus on the urgency of our challenge for the future," it says.

At the first of several launch events earlier this year, the World Conservation Union (IUCN) argued that species are currently dying out at around 1,000 times the natural background rate and we are in the midst of the planet's sixth major mass extinction.

"At risk of extinction worldwide are 21% of mammals, one in three amphibians, one in eight birds and 27% of reef building corals," says Jane Smart, director of the IUCN's Biodiversity Conservation Group.

"Extinction is irreversible; once a species is extinct it is gone forever. The loss of this beautiful and complex natural diversity that underpins all life on the planet is a serious threat to humankind."

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