When a frog species disappears, life itself is weakened. Some species are resistant to diseases which kill closely related ones: for instance, AIDS is lethal to humans but not to our very close cousins the apes. Maintaining biological diversity is a vital necessity.
OTOH even if there was only one language left on the Earth, new languages would appear in the course of centuries if communications between human communities became difficult.
Dead languages can be resurrected if certain conditions are met. But no new animal species is likely to appear in our lifetimes, and dead species cannot be resurrected.
I disagree with this. When a species of frog disappears, then an opportunity arises for another species to move into that niche and (possibly) evolve into a new species.
In the long run, yes.
Rik wrote:Life evolves - it is conditioned to evolve, and make the best use it can of any opportunity that presents itself in the environment. While the range of environments is being narrowed through human activity (such as excessive logging in the tropics), it is also being expanded through human activity (cities and foxes, landfills and seagulls).
That's true. But. We're creating a world-wide monoculture, as a few species which adapt well to human cities, notably rats, seagulls, and humans to name a few. This sucks, in the short run.
Hmm, I'm not being able to argue this effectively, logically at the moment. It's all sentimental. From my paleontologist point of view, it's all inconsequential. Mass extinctions open space for exciting new animal groups, in 10 million year or so. But, if we really send the world ecosystem into such a cascade, the chance that we ourselves survive it are not good. And I happen to like humans. Evolutionary pre-programming, you know.
From my more general biologist point of view, the loss of information and beauty, if nothing else, on that scale is a truly hideous thought.
Rik wrote:And while global warming is a worrying trend, it is not as if the planet hasn't been there before. The past few million years have been some of the coldest on record (thank you, Antarctica).
That's absolutely true. Problem is, "global warming" is a bad name for it. It's more "climate destabilization". And the past few million years have been the least stabile climate on record. And we don't know how bad it's going to be, or what it's going to do. It's possible that plants will accelerate growth to absorb extra CO2 and drain it back down, returning to normal. It's also possible that plant respiration rates will go up even faster, leading to a poistive feedback cycle, producing more CO2.
It's possible global warming will warm the globe. But it's also possible it will send a rush of fresh water into the oceans from melting ice caps, disrupting salinity-driven ocean currents, shutting down a major global temperature regulation system, which could bury, say, London in ice in a few thousand years.
And its a process with great momentum. A lot of effects that are produced today will unfold over the next 50+ years. Which means even if we cut human modification of atmosphere composition right now, it would still get worse for quite a few decades, before even started to get better. And, of course, we're not cutting those processes right now, so it will be that much longer.
I truly believe that life will go on, what ever humans do, but its still up in the air whether humans will be around to see the recovery from the crisis.
But, it is instructive to look at Mars and Venus. Both once had favorable condidtions. Then something went terribly, terribly wrong on each planet. Positive feedback loops, runaway effect crashed each planet; something littel gets started, but its self reinforcing and eventually the you've got CO2 ice caps, or 460? (C) surface temperatures.
Those two and Earth are the only data points we have. By our limited knowledge, statistically, life-nurutring conditions on Earth should have crashed billions of years ago. They haven't, probably mostly because Earth has some significan advantages over Mars and Venus. But we don't have any guarantee how long that'll keep the Earth going.
No guarantees, and it behooves us, in this position of doubt to play it, at the very least, a lot safer than we are currently.
Rik wrote:Biodiversity in a colder global climate is more restricted, and species tend to be physically smaller - the giant mammals of the Paleogene Age were long gone before our ancestors learned to hunt in packs. A warmer climate may well lead to greater biodiversity in a few thousand years time.
The giant mammals of the Paleogene were long gone, replaced by the giant mammals of the Neogene, and then they in turn were partially replaced by new giant mammals in the Pleistocene. Then our ancestors learned to hunt in packs. Were are the giant mammals now? Well, Africa. And one or two scattered elsewhere. But the megafaunas are gone, man. And it hasn't been for very long.
A warmer climate will probably lead to more biodiversity, but probably not in a few thousand years. Maybe ten thousand years. Maybe it'll take a lot longer, depending on what exactly happens. A more disrupted climate will not
lead to greater biodiversity. The Permian-Triassic taught us that. Yes, every mass extinction has lead, eventually, to an explosion of exciting new forms and lineages. But on several occaisions, it has taken 10 Million years for diverstity to return to previous levels.
Sorry to come down so hard. I sympathize with your position, it's an easy position to come to, after studying a bit of paleo. But I think it's one that's born of half-knowledge, and that it is a dangerous one. At least to any future I want to see.
Tuomas Koukkari wrote:The Earth has survived mass extinctions before. We're nowhere close to what have been the worst situations.
I disagree. The last 50,000 years (an fairly brief geologic time) have seen elevated levels of extinction noticable elevated from background levels. These rates have accelerated steadily over tha period. I think it is all to possible to see this developing into a Class 2 mass extinction. There are some estiamtes from pretty believable sources along the lines of 24% of mammals extinct in the next 30 years; and 50% (some estimate higher) of [i]all[i] animal species extinct in the next 100 years.
The other great apes could go in the next decade, from habitat loss and the bush meat trade. I don't know about you, but I'd have a hard time living with that.