What's happening to our biodiversity?
Extinction
Some scientists believe that we are now witnessing the sixth mass extinction, the only mass extinction to be caused by a single species - humans.
Extinction over millions of years
Extinctions of species have been occurring since the first life forms evolved. It is estimated that about 30 billion species have lived since multicellular life evolved, but only about 0.01% of that number live on Earth today. There have been periods in the Earth's long history when mass extinctions have occurred. Some scientists believe that we are now witnessing the sixth mass extinction, the only mass extinction to be caused by a single species - humans.
Environmental change over thousands of years
Indigenous people have been interacting with Australia's natural environment for tens of thousands of years. During this time they undoubtedly influenced the course of evolution. Whatever the level of impact created by Australia's Indigenous people, they adapted their own lifestyles and survived in all parts of the continent for many thousands of years.
There is much debate about the kind of impact Indigenous people have had on this land. They used fire as a land management tool long before the arrival of Europeans, and this is thought to have affected vegetation patterns. Their hunting practices may have affected population levels of some animals, and the building of fish traps in coastal and inland rivers may also have had environmental effects.
While there have certainly been extinctions in Australia during the past 40,000 to 50,000 years, scientists are unsure about which, if any, were caused by Indigenous people. Did megafauna, such as Procoptodon (the giant short-faced kangaroo) or Diprotodon (the giant wombat-like marsupial), that used to roam Australia, become extinct because of climate change or because of hunting?
Environmental change over the last few hundred years
Since the arrival of Europeans in Australia, just over 200 years ago, there has been an extraordinary increase in the rate of environmental change and in the loss of biodiversity.
The main factor in the loss of biodiversity is the increased rate of population growth. This has led to habitat change through land clearing and urbanisation, hunting and exploitation. The introduction of new species is also a threat to Australia's biodiversity.
