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World wildlife populations halved in 40 years - report | World wildlife populations halved in 40 years - report |
(about 11 hours later) | |
The global loss of species is even worse than previously thought, the London Zoological Society (ZSL) says in its new Living Planet Index. | The global loss of species is even worse than previously thought, the London Zoological Society (ZSL) says in its new Living Planet Index. |
The report suggests populations have halved in 40 years, as new methodology gives more alarming results than in a report two years ago. | The report suggests populations have halved in 40 years, as new methodology gives more alarming results than in a report two years ago. |
The report says populations of mammals, birds, reptiles, amphibians and fish have declined by an average of 52%. | The report says populations of mammals, birds, reptiles, amphibians and fish have declined by an average of 52%. |
Populations of freshwater species have suffered an even worse fall of 76%. | Populations of freshwater species have suffered an even worse fall of 76%. |
Severe impact | Severe impact |
Compiling a global average of species decline involves tricky statistics, often comparing disparate data sets - and some critics say the exercise is not statistically valid. | |
The team at the zoological society say they've improved their methodology since their last report two years ago - but the results are even more alarming. | The team at the zoological society say they've improved their methodology since their last report two years ago - but the results are even more alarming. |
Then they estimated that wildlife was down "only" around 30%. Whatever the numbers, it seems clear that wildlife is continuing to be driven out by human activity. | Then they estimated that wildlife was down "only" around 30%. Whatever the numbers, it seems clear that wildlife is continuing to be driven out by human activity. |
The society's report, in conjunction with the pressure group WWF, says humans are cutting down trees more quickly than they can re-grow, harvesting more fish than the oceans can re-stock, pumping water from rivers and aquifers faster than rainfall can replenish them, and emitting more carbon than oceans and forests can absorb. | The society's report, in conjunction with the pressure group WWF, says humans are cutting down trees more quickly than they can re-grow, harvesting more fish than the oceans can re-stock, pumping water from rivers and aquifers faster than rainfall can replenish them, and emitting more carbon than oceans and forests can absorb. |
It catalogues areas of severe impact - in Ghana, the lion population in one reserve is down 90% in 40 years. | It catalogues areas of severe impact - in Ghana, the lion population in one reserve is down 90% in 40 years. |
In West Africa, forest felling has restricted forest elephants to 6-7% of their historic range. | In West Africa, forest felling has restricted forest elephants to 6-7% of their historic range. |
Globally, habitat loss and hunting have reduced tigers from 100,000 a century ago to just 3,000. | |
In the UK, the government promised to halt wildlife decline - but bird numbers continue to fall. | In the UK, the government promised to halt wildlife decline - but bird numbers continue to fall. |
The index tracks more than 10,000 vertebrate species populations from 1970 to 2010. It reveals a continued decline in these populations. The global trend is not slowing down. | The index tracks more than 10,000 vertebrate species populations from 1970 to 2010. It reveals a continued decline in these populations. The global trend is not slowing down. |
'New method' | 'New method' |
The report shows that the biggest recorded threat to biodiversity comes from the combined impacts of habitat loss and degradation, driven by what WWF calls unsustainable human consumption. | The report shows that the biggest recorded threat to biodiversity comes from the combined impacts of habitat loss and degradation, driven by what WWF calls unsustainable human consumption. |
The report notes that the impacts of climate change are becoming of increasing concern - although the effect of climate change on species until now is disputed. | The report notes that the impacts of climate change are becoming of increasing concern - although the effect of climate change on species until now is disputed. |
WWF is keen to avoid despair. It points to conservation efforts to save species like: | WWF is keen to avoid despair. It points to conservation efforts to save species like: |
Previously, the Living Planet Index was calculated using the average decline in all of the species populations measured. The new weighted methodology analyses the data to provide what ZSL says is a much more accurate calculation of the collective status of populations in all species and regions. | Previously, the Living Planet Index was calculated using the average decline in all of the species populations measured. The new weighted methodology analyses the data to provide what ZSL says is a much more accurate calculation of the collective status of populations in all species and regions. |
A ZSL spokesman explained to BBC News: "For example, if most measurements in a particular region are of bird populations, but the greatest actual number of vertebrates in the region are fish, then it is necessary to give a greater weighting to measurements of fish populations if we are to have an accurate picture of the rate of population decline for species in that region. | A ZSL spokesman explained to BBC News: "For example, if most measurements in a particular region are of bird populations, but the greatest actual number of vertebrates in the region are fish, then it is necessary to give a greater weighting to measurements of fish populations if we are to have an accurate picture of the rate of population decline for species in that region. |
"Different weightings are applied between regions, and between marine, terrestrial and freshwater environments. We are simply being more sophisticated with the way we use the data." | "Different weightings are applied between regions, and between marine, terrestrial and freshwater environments. We are simply being more sophisticated with the way we use the data." |
"Applying the new method to the 2008 dataset we find that things were considerably worse than what we thought at the time. It is clear that we are seeing a significant long-term trend in declining species populations." | "Applying the new method to the 2008 dataset we find that things were considerably worse than what we thought at the time. It is clear that we are seeing a significant long-term trend in declining species populations." |
Correction: An earlier version of this story said that tiger numbers in Nepal had reduced from 100,000 a century ago to just 3,000. Those figures are in fact for global tiger numbers. | |
Follow Roger on Twitter @rharrabin | Follow Roger on Twitter @rharrabin |