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Human actions are driving species to extinction

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In his Academy Award winning documentary “An Inconvenient Truth”, Al Gore describes “…a mass extinction crisis, with a rate of extinction now 1,000 times higher than the normal background rate.”

But how do we know that? And what does it mean?

The rate at which species are going extinct is rather like the rate at which people die. Look at the obituaries in a town’s local paper, count them up and, if you know how many people live there, calculate the death rate. So we expect perhaps one in 80 people to die each year, or roughly one in four thousand each week – or 250 deaths per one million people per week on average.

We can do the same thing with species. Scientists describe new species in their publications in a way that the general population can follow them from the date of their description — their scientific birth if you like — to the present, counting how many died off in the interval.

Birds are the best-known example: following a sample of about 1,000 species for the past century, 13 have become extinct – or to use the standard method of reporting, 130 extinctions per million bird species per year.

So how many future extinctions should we expect? While the fossil record gives us some idea, it’s very crude and very hard to interpret, except when they are mass extinction events, such as the one that wiped out the dinosaurs. Interestingly, we can get important insights into what the natural rate should be from molecular studies that tell us how fast species diversify — that is, how fast they are born.

For example, we humans split from our nearest common ancestor with chimps about 10 million years ago. While the exact age is contentious, it’s about typical. Species form at the rate of about one new species per 10 million species per year. So, compare how fast species are dying and how fast they are being born, and yes, species are dying out a thousand times too fast.

Why can’t you just say how many species are dying out each year?

The problem is that we do not have a good idea of how many species there are. Scientists have described almost two million species. We know how many birds there are, because there are legions of birdwatchers to spend billions of dollars each year to follow their passion. But insects? Or fungi? Not a chance.

So, if human actions continue to exterminate species at the current rate for another century, then we could lose a fraction of species comparable to those mass events in the geological past. This hasn’t happened yet.

Can we prevent it? The answer must be an emphatic yes.

There are two kinds of species at risk of extinction. The first group are those familiar animals, such as lions and tigers and bears. These incredible beasts remain at high risk of extinction in the coming decades. There are, however, excellent program, such as National Geographic’s Big Cats Initiative, which works with people in the communities where such big, fierce, creatures live to minimize conflict. As an example: Lions kill people’s livestock — their wealth — and, understandably, humans retaliate by killing lions. Better to protect those livestock and far fewer lions are killed.

The second kind of species are by far the most numerous. These are species with small geographic ranges — sometimes no more than a single mountain top, or a local patch of forest. Habitat destruction is the main reason why human actions drive these species to extinction.

The geography of this destruction is also important.

Two-thirds of all species on land live in tropical moist forests and a large number of the species at risk of extinction live in a subset of these forests. These include the northern Andes, the coastal forests of Brazil, Madagascar, islands in south-east Asia, the Philippines, and about 20 other places, mostly in the tropics. If conservation efforts are concentrated in these areas, we can have a disproportionately positive effect at reducing that extinction rate.

So then how can we act locally? Well, not only have we destroyed the forests in these places, we’ve left what remains in tatters; small, fragile forest fragments too small to maintain viable populations. But it can be fixed. Organizations such as SavingSpecies raise money for local conservation groups in the key battlegrounds against species extinction.

There is no doubt that the world is facing the challenges of global warming and mass species extinction. But those challenges are compounded by the fact that many of the world’s leaders are either turning a blind eye to these challenges or, worse, denying the problems even exist. Perhaps now more than at any other time in human history, all of us must stand up for the future of nature.

© The Mark News

©2020 GPlusMedia Inc.

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worse, denying the problems even exist

Yes, I can imagine this, especially in post-truth America. Perhaps the same people who deny anthropogenic climate change. "Everything is Awesome" under President Business.

4 ( +5 / -1 )

I remember Al Gore saying all the arctic ice will be gone by 2013. Arctic ice has actually increased by 50% since 2012.

-3 ( +1 / -4 )

Species did out all the time. The Earth is a death trap. And not just for humans. All life is at risk.

We need to get off this rock for the species to continue. And to other planets in the Solar system isn't far enough. The Sun is going to die. We need to get to another arm of the galaxy, at least that far, to avoid regional catastrophes. Otherwise, it isn't just humans, but all life in this part of the galaxy will be killed off.

Wish that Al Gore learned that Correlation does not imply causation. Winning an award doesn't always mean it is true or deserved. Just look at President Obama's Nobel Peace Prize. Not earned and definitely not deserved.

-4 ( +0 / -4 )

Mr. Stuart Pimm, Sir,

You write, "For example, we humans split from our nearest common ancestor with chimps about 10 million years ago."

This statement, if true, would mean that humans derived from chimps. And furthermore, that chimps evolved from a previous animal, and so on. To be sure, Darwinian evolution makes no claims on the origins of life on this planet, but it does give an account for the variety of life that we see today. It explains how all animals came into existence through an unguided process. No God or intelligence was involved. (at least, this is the Darwinian claim)

Therefore, all animals owe their existence to an unguided process. They were not brought into existence by a Transcendent God, they came to be what they are by a series of unguided steps. What follows from this?

Well, for one thing, what is....is. There is no objective morality to any action other than what we assign to it. Animals kill other animals. Animals go extinct at different rates throughout history. Period. Since there is no design, no ultimate plan, then the rate of extinction that we see in the fossil record, just happens to be what happened throughout the millions of years of Earth history. I can no more say what ought to be the rate of extinction than anyone else. After all, the well known Maxim that one cannot derive an ought from an is applies here.

You continue with, "But those challenges are compounded by the fact that many of the world’s leaders are either turning a blind eye to these challenges or, worse, denying the problems even exist. "

What "Problem"? Higher extinction rates than what occurred previously? Why is that a "problem"?

Keep in mind, there is no Design here. Nothing is as it ought to be, it just is.

Humans responsible for the accelerated rate of extinction of certain animals? So? Since there is no Designer, no ultimate plan, nothing other than what we deem to be correct, then ANY rate could be deemed acceptable. There is no ultimate guidebook by which we are able to look up the extinction rates of animals and say, "Oh, the rate is off here...we ought change our behaviour."

Your worldview, which is made plain by your statement that humans evolved from chimps cannot serve as a grounding for your preaching that we OUGHT do something about the extinction rates of animals.

Now, I DO believe that we as humans have been poor stewards of Nature. That we have destroyed our planet with blatant disregard, and that we OUGHT change our behaviour. But, my grounding for this is much different than yours. In my worldview, my ancestors were not chimps, or even fish.

In other words, I agree with your conclusion that we as humans are responsible for the extinction of certain species. I also agree that we ought be MUCH BETTER stewards of nature. But, my conclusion Follows from my worldview.

Perhaps, you should, for arguments sake, be honest with yourself and follow your presuppositions to their logical conclusion. A world where there are no "oughts", but only those that we deem to be correct for us. A world where a child is different from a chimp only in a matter of degree, and not in kind.

To quote Hobbes, you would find yourself in a bleak world where there is:

“continual fear, and danger of violent death; and the life of man, solitary, poor, nasty, brutish, and short”.

But then, this is after all a Darwinian world.

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