20110824_R4

Source: BBC Radio 4: Today Programme

URL: http://news.bbc.co.uk/today/hi/today/newsid_9571000/9571592.stm

Date: 24/08/2011

Event: BBC's Tom Feilden discusses biodiversity and mass extinction

People:

• Tom Feilden: BBC Today Programme science correspondent
• Dr Derek Tittensor: Research scientist working on issues of marine biodiversity
• Justin Webb: Presenter, BBC Radio 4 Today programme

Justin Webb: I'm rather surprised we haven't counted them before.

Tom Feilden: Yes, it does seem incredible, doesn't it. But until now our best estimate, for the number of species we share the planet with, was anything from three to one hundred million. That's quite a wide margin for error, and pretty close to useless, actually, when it comes to really understanding the range of biodiversity on Earth. Now those figures come from surveying small patches of habitat - rainforest or salt marsh, or whatever - then aggregating them and extrapolating out to get an estimate for the whole planet. What the researchers in this study, published in the journal PLoS Biology, have done is to take a very different approach, based on the hierarchical classifications of life - kingdom, phylum, class, order, etc. Now we know a lot about what's happening at the top of that pyramid, for a very wide range of species, and the team have used that information to extrapolate down through the subsequent levels. I talked to one of the co-authors of the report, Dr. Derek Tittensor from the UN's World Conservation Monitoring Centre in Cambridge.

Derek Tittensor : Well, what we've done that's different is we've used relationships among these higher taxonomic ranks to deduce what's going on at the species level. So we're extrapolating downwards from the kingdom level - so kingdoms are things like animals and plants - down through the levels of biological organisation to species. So we're not actually using information at the species level. Rather, we use information at other levels to estimate or extrapolate what's going on with the number of species.

Tom Feilden: Now, that gives a much more accurate, statistically significant estimate of the numbers in each tier, and results in a figure of 8.74 million species, plus or minus 1.3, so we're still not at an exact figure.

Justin Webb: Is it a figure that matters, though? Does it tell us something that is significant and useful?

Tom Feilden: Well, it matters, because if you don't know what you've got, you can't protect it and you can't be sure what you're losing. And we are losing species at a truly alarming rate. I mean, estimates vary, but the figure could be as high as 30,000 a year, or three an hour. Now, I reckon that that adds up to about four since the start of the programme. And it's a rate which compares with previous mass extinctions in the history of the planet, like the one that wiped out the dinosaurs, 65 million years ago, and has been dubbed the sixth mass extinction event in the history of life on Earth. And the problem is, we don't really understand the ecological and biological processes which give rise to those species, or what the consequences of eradicating them could be. So it could be we're significantly undermining the ecosystem services - oxygen to breathe, clean water to drink, and grow crops, that sort of thing - that we need to survive without actually realising. And that's why most biologists believe this biodiversity crisis is actually even more profound - a more profound threat to our future even than global warming.

Justin Webb: And not necessarily linked.

Tom Feilden: No, I mean, obviously there will be some overlap, some of the events occurring to do with climate change will have an impact on species, diversity and where they locate. I think there was a report last week which showed that animals were moving either away from the Equator or higher up mountains. And obviously, if you keep moving up a mountain to stay in your band, eventually you get to the top and you've got nowhere else to go.