Extinctions Just as Damaging as CC/AGW

[BNC Moderator]

A new paper in the prestigious science journal Nature assesses one of the big questions in ecology today: How do species extinctions rack up compared to other global change issues like global warming, ozone holes, acid rain, and nutrient pollution (overfertilization). Evidence is mounting that extinctions are altering key processes important to the productivity and sustainability of Earth's ecosystems.

Will the Anthropocene promote the greatest extinction even the Earth has seen thus far?

Can governments do more to halt the process? If so what do you suggest? Is tackling climate change enough?

[anonposter]

What we can do to halt the process would depend on why a given species is going extinct (yes, I know that's a tautology but I think it needs to be said, there won't be a one size fits all answer). It's also worth noting that we've largely solved the ozone hole problem (though we still have to wait a bit for those chlorine (and bromine) radicals to leave the stratosphere).

Habitat destruction is a major part of extinction so returning unused agricultural land to nature could help some species, introduced species can also cause problems so removing the new species could help there (though I do think the problem those extinctions will cause us is overstated, personally I'm also glad we've driven a couple of species to extinction, see if you can guess which two).

Zoos and captive breeding may well be the only hope for some species (and we may even need cloning technology, once we get the bugs worked out of course).

[davidm]

One contributor to the degrading of biodiversity is introduced species that lack any natural limits in their new environment. I recall this piece from George Monbiot.

This month governments meet at Nagoya, in Japan, to review the Convention on Biological Diversity. It has, so far, been a dismal failure. Perhaps the starkest botch has been their inability or unwillingness to control the spread of invasive species. The stories I am about to tell read like a gothic novel.

Consider, for example, the walking catfish, which is now colonising China, Thailand and the US, after escaping from fish farms and ornamental ponds. It can move across land at night, reaching water no other fish species has colonised. It slips into fish farms and quietly works through the stock. It can burrow into the mud when times are hard and lie without food for months, before exploding back into the ecosystem when conditions improve. It eats almost anything that moves.

Its terrestrial equivalent is the cane toad, widely introduced in the tropics to control crop pests. It's omnivorous and just about indestructible: one specimen was seen happily consuming a lit cigarette butt. Nothing which tries to eat it survives: it's as dangerous to predators as it is to prey. Unlike other amphibians, it can breed in salty water: it's as if it had waddled out of the pages of Karel Capek's novel War With the Newts.

The world's most important seabird colony – Gough Island in the South Atlantic – is now being threatened by an unlikely predator: the common house mouse. After escaping from whaling boats 150 years ago, it quickly evolved to triple in size, and switched from herbivory to eating flesh. The seabirds there have no defences against predation, so the mouse simply walks into their nests and starts eating the chicks alive. Among their prey are albatross fledglings, which weigh some 300 times as much as the mice. A biologist who has witnessed this carnage observed that "it is like a tabby cat attacking a hippopotamus".

On Christmas Island the yellow crazy ant does something similar: it eats alive any animal it finds in its path. It is also wiping out the rainforest, by farming the scale insects that feed on tree-sap. Similar horror stories are unfolding almost everywhere. The species we introduce, unlike the pollution we produce, don't stop when we do. A single careless act (think of the introduction of the rabbit or the lantana plant to Australia) can transform the ecology of a continent.

Some of these examples sound a little embellished but it doesn't detract from the basic point.

[davidm]

This link provides an extensive discussion on the connection between the loss of biodiversity and extinctions. Human overpopulation as a principal contributing factor is unavoidable.

Despite knowing about biodiversity’s importance for a long time, human activity has been causing massive extinctions. As the Environment New Service, reported back in August 1999 (previous link): “the current extinction rate is now approaching 1,000 times the background rate and may climb to 10,000 times the background rate during the next century, if present trends continue [resulting in] a loss that would easily equal those of past extinctions.” (Emphasis added)

A major report, the Millennium Ecosystem Assessment, released in March 2005 highlighted a substantial and largely irreversible loss in the diversity of life on Earth, with some 10-30% of the mammal, bird and amphibian species threatened with extinction, due to human actions. The World Wide Fund for Nature (WWF) added that Earth is unable to keep up in the struggle to regenerate from the demands we place on it.

[anonposter]

David M: You still have yet to provide any evidence that it's the size of human population which is the problem and not merely a refusal to use the best available technology (not to mention that in the first world we've been returning farmland to nature, while increasing food production which is something you'd expect to make things better on the habitat loss front). Even if a large population must lead to mass extinction that's better than your alternative of a smaller population size, especially when we consider what it'd take to reduce population.

Introduced species happen regardless of population size, all you need is for people to move around and wittingly or unwittingly bring animals with them (it can even happen naturally).

I should also note that it appears that estimates of extinction rates from 1999 and 2005 are larger than reality (though we've still got a problem on our hands).

[davidm]

I have a feeling Anon that you are going to continue to make the argument one of overpopulation vs. best environmental use. It is obviously both. Read through my link. The point is made redundantly and I might add it seems a little odd to have to prove the obvious.

As for your link I'll leave you with this quote.

Jean-Christophe Vié, deputy head of species survival at the International Union for the Conservation of Nature, agrees better baseline data on species is badly needed. He says IUCN doesn't use the SAR method. But, he points out, "a twofold miscalculation doesn't make much difference to an extinction rate now 100 to 1000 times the natural background".

Hubbell and He agree: "Mass extinction might already be upon us."

[anonposter]

May 30, 2012 10:49:47 GMT 9.5 @davidm said:

I have a feeling Anon that you are going to continue to make the argument one of overpopulation vs. best environmental use.

You're the one who keeps bringing up 'overpopulation', I'm just noting that it doesn't really exist, whatever problems you claim from it come from other causes (and tend to be amenable to technofixes).

May 30, 2012 10:49:47 GMT 9.5 @davidm said:

It is obviously both. Read through my link. The point is made redundantly and I might add it seems a little odd to have to prove the obvious.

A lot of things which seem obvious are also wrong.