The world's wildlife populations are dying out faster than we previously thought.
A paper called the Living Planet Report 2014 was released by the London Zoological Society (ZSL) earlier today, and it shows how populations have declined by an average of 52 per cent over the 40 years from 1940 to 2010.
To conduct the analysis, researchers used a measurement called the Living Planet Index (LPI) as an indication of the health of over 10,000 populations of mammals, birds, reptiles, amphibians and fish.
There was some variation between climates; The species in the temperate zones declined by 36 per cent during the period, while in tropical regions, meanwhile, there was a decline of 56 per cent.
One explanation provided by ZSL for this disparity is that the majority of habitat destruction since 1970 has taken place in the tropics,with most habitat alteration and destruction in temperate regions taking place prior to this.
The species in fastest decline
Marine species such as turtles, sharks and large migratory birds, declined by 39 per cent between 1970 and 2010. Terrestrial animals such as rhinos and big cats went down by the same amount.
One of the land species most affected by habitat damage is tigers, which have gone down from 100,000 a century ago to just 3,000. In Ghana, the lion population in one reserve is down 90 per cent compared to 40 years ago.
But freshwater species have been hit hardest – these went down by 76 per cent during the period, which is almost as much as the combined decline of land and marine species. ZSL says the main threats to freshwater species are habitat loss and fragmentation, pollution and invasive species. Changes to water levels and freshwater system connectivity – for example through irrigation and hydropower dams – have a major impact on freshwater habitats.
Perhaps the most alarming finding of all, however, is the speed at which the populations are declining compared to previous estimates – for all three types of species, a similar analysis done two years ago for 1970 to 2008 showed a much slower decline.
What's driving the loss?
According to the report, the biggest recorded threat to biodiversity comes from the combined impacts of habitat loss and degradation, driven by what WWF calls unsustainable human consumption.
It says the loss of habitat to make way for human land use – particularly for agriculture, urban development and energy production – continues to be a major threat, compounded by hunting.
“By taking more from our ecosystems and natural processes than can be replenished, we are jeopardizing our very future,” the report says.