How life on Earth recovers after a devastating mass extinction

Original post from The Conversation

‘…………..By David BondNERC Advanced Research Fellow and Lecturer in Geology at University of Hull

Bye bye humanity…. now what? NASA
Bye bye humanity…. now what? NASA

Life on Earth is entering the greatest mass extinction since the death of the dinosaurs, according to a major new study – and humans may be among the casualties. Such a catastrophic loss of species would leave a huge hole in the world’s ecosystems, and all sorts of weird and wonderful life would evolve into the vacancies left behind.

To consider what life after a mass extinction might involve, we can look to the past. There have been five major mass extinctions in Earth’s history – though colleagues and I recently proposed a sixth – and comparing current rates of change to the geological record of the “Big Five” extinctions suggests that this time the warning signs are real.

So let’s be pessimistic, and assume the apocalypse is going to happen. What does Earth look like afterwards?

The greatest crisis in history

The Permian-Triassic boundary (251m years ago) saw the greatest crisis in Earth’s history, when at least 90% of speciesdied off. Even insects suffered huge losses – the only mass extinction in their long history.

The event is widely attributed to the effects of the Siberian Traps – huge volcanic outpourings of lava and associated greenhouse gases, in what is now northern Russia. This lead to global warming, ocean acidification and acid rain, marine oxygen depletion and poisoning by toxic metals such as mercury. Imagine today’s gloomiest climate predictions, but cranked up a few notches.

The few species that survived gave rise to all life thereafter and there has not been such a profound restructuring of ecosystems since, perhaps because this “survival of the fittest” rendered their descendants more tolerant to global change.

Trilobites prospered for 270m years, but they didn’t make it into the Triassic.  Heinrich Harder
Trilobites prospered for 270m years, but they didn’t make it into the Triassic. Heinrich Harder

What did the planet look like in the Early Triassic? It was hot – hot as hell – and seemingly lifeless over vast areas. Sea-surface temperatures reached up to 45°C in the tropics. In the vast Pangaean desert it was probably even hotter.

The heat caused land animals, marine reptiles and fish to disappear from the fossil record in all but the high latitudes, which were presumably a little cooler, for millions of years. In fact, there are several “gaps” in the Early Triassic.

The bulk of the world’s coal today derives from vast swathes of the Permian seed fern Glossopteris – a prominent casualty, whose loss led to a “coal gap” of at least 12m years.

A series of Early Triassic “fungal spikes”, where rocks contain greatly enhanced numbers of spores, has been attributed to huge amounts of dead plant and animal matter available for fungi to feed upon. The heat, and acid rain-induced destruction of soils (which would have smelled of vanilla), must have rendered the planet largely uninhabitable.

Without plants there are no plant-eaters. Without herbivores there were no carnivores. One of the few “big” survivors on land was the “shovel lizard” Lystrosaurus, an odd-looking vegetarian which, in the absence of predators and competitors, diversified with some success during the Triassic.

The shovel lizard dominated southern Pangaea before dinosaurs showed up.  Nobu Tamura, CC BY
The shovel lizard dominated southern Pangaea before dinosaurs showed up. Nobu Tamura, CC BY

The carnage was worse in the oceans, where up to 96% of species went extinct. The loss of all reef-building corals led to a 10m year Early Triassic “reef gap”. Think of it: a world without reefs – and without all the diverse and abundant life they support.

But Earth wasn’t quite lifeless – and as well as Lystrosaurusthere were marine success stories amid the horror. Claraia was an opportunistic genus of scallop-like bivalve that survived the end-Permian, and then quickly diversified to fill the vacant niches left by the almost total annihilation of the dominant Permian sea-floor dwellers, the brachiopods. Claraia was tough and could withstand very low oxygen levels – a trait that came in very handy when most sea-bed life was being starved of oxygen.

Dinosaur doom

Perhaps the most famous and eye-catching extinction saw the death of the (non-avian) dinosaurs around 66m years ago at the

Claraia – seabed survivors.  Museum Gröden / Wolfgang Moroder, CC BY-SA
Claraia – seabed survivors. Museum Gröden / Wolfgang Moroder, CC BY-SA

Cretaceous-Tertiary boundary. As well as picture-postcard victims such as T. rex, the turnover in tiny plankton at the other end of the food chain saw an end to the formation of the famous Cretaceous chalk cliffs that are so widespread across Europe (the period’s name comes from the German “kreide”, meaning chalk).

Whether it was a meteorite, more massive volcanic eruptions, or a bit of both that did the damage, in comparison to the Permian-Triassic scenario, the death of the dinosaurs was more modest (around 75% of global species lost) and the recovery was more rapid. Either Earth sorted itself out more quickly, or, following the “Great Dying” 185m years previously, life had become better at adapting to, and evolving with, stress.

Of course, dinosaurs are not exactly extinct. Birds are highly evolved dinosaurs that derive from the few dinosaurian survivors of the Cretaceous-Tertiary (K-T) event and nobody can deny their evolutionary success in the 66m years since the demise of the chicken-like T. rex.

Life soon flourished after the dinosaurs were gone.  Jay Matternes
Life soon flourished after the dinosaurs were gone. Jay Matternes

Crocodiles and alligators – the closest living relatives of birds – are among the other prominent survivors. While it’s clear that birds’ ability to fly to oases of calm and plenty allowed them to flourish amid the upheaval of the K-T boundary, it is not obvious why crocodilians survived. Theories suggest their cold-blooded bodies (vs. the supposed warm-blooded theropod dinosaurs), their fresh or brackish water habitat or even their high IQ enabled them to flourish.

The good news amid all this death and destruction is that life on Earth always recovers, even when it has been really badly damaged. Without extinction, there is no evolution – the two are intrinsically linked.

The earliest dinosaurs evolved 20m years after the Permian-Triassic losses. Their evolution was almost certainly driven by a freshening of climate during the “Carnian Pluvial Event” (when it rained, a lot), new-found lush vegetation and the swathes of ecospace available to colonise.

Dinosaurs lived for 165m years before their demise, but without their death, humans probably wouldn’t be here today to do their damage. Mammals, of course, were the great beneficiaries of the dinosaurs’ downfall.

If humans are indeed doomed then we won’t be around to see what evolves to replace us. But rest assured, we geologists don’t take ourselves too seriously – we know that Earth is bigger than us, and it will bounce back.  ………….’

When humans go extinct: How life will evolve after we’re gone

Original post from Salon

‘………..The sixth extinction could wipe out up to half of Earth’s species. Michael Tennesen tells us what might happen next

The sixth mass extinction is nearly upon us. Species on Earth are dying out at a rate one thousand times greater than they were before humans began altering the environment. By the end of this century, scientists warn, anywhere from 20 to 50 percent of the species on Earth could be lost forever.

 And among those who might not make it out the other side, says science writer Michael Tennesen, are humans.

It’s to be expected: No species lasts forever, and in our relatively short existence, humanity has done an impressively good job of undermining the forces necessary for our survival. But while we’re already taking a number of species out with us, Tennesen argues, nature is resilient: the end of man won’t necessarily mean the end of life itself. “Plants, animals, and microbes will survive, adapt, diversify, and proliferate,” he writes of life after man. “New plants will evolve to vanquish our monocultures of corn, wheat, and rice. With far fewer animals around, those species that survive the bottleneck of extinction will move into newly abandoned spaces. With little competition, they will thrive and rapidly evolve.”

We know that, he adds, because this sort of thing has happened in the past.

In “The Last Species: The Future of Evolution in the Aftermath of Man,” Tennesen looks to the previous five extinctions for clues as to what we can expect from the sixth. He spoke with Salon about how recognizing our place in nature might help us last just a little bit longer, and how an eventual Earth without man, at least in our current incarnation, won’t necessarily be such a terrible place. Our conversation, below, has been lightly edited for length and clarity:

A lot of us look at these studies about pollution and climate change and extinction on a very day-by-day, headline basis. What was the value for you of stepping back and taking a more pulled-back, planetary perspective on these issues?

I was influenced by a paper that Anthonky Varnofsky from the University of California at Berkeley wrote, about his idea that we are entering a mass extinction event. People who study life on Earth think that extinction has a dual side: it could be a catastrophe or it could be an opportunity. The comet that fell out of the sky at the end of the Cretaceous period knocked out the dinosaurs, but made way for mammals and man.

So I’m trying to look at what can happen next. And to get an idea of what can happen next, I kind of had to pull back and look at the history of life on Earth with the idea: how does life recover from catastrophe? What things can you see in both events that might possibly be repeated in the future?  I wanted to look at the whole concept. There was a book by Allen Weissman, “The World Without Us,” where he talked about what it would be like tomorrow if man disappeared and how long it would take for man’s infrastructure to come down, for New York to fall.  I just wanted to look at it from more of a reality standpoint: What would the biology be like in such an event?

When you’re looking back at some of these lessons we can learn from past mass extinctions, what are some of the most important things you came across, that we should be paying attention to?

If you look at the past, the driver of four out of the five mass extinctions has been carbon dioxide. I went to Guadalupe National Park and took a hike with the national park biologist Jonena Hearst to Capitan Reef, which was just this explosion of life that existed back in the Permian Era, 250 million years ago, just before the Permian extinction. It showed just how susceptible life is to chemicals in the environment, and the litany of things that was going on during the Permian extinction, which was the greatest extinction we’ve ever had: 90 percent of life was knocked out of the ocean; 70 to 75 percent on land. The high CO2 content and greenhouse gases and other problems — sulfur dioxide release, major changes in the ocean currents — these are some of the things we’re dealing with now. I don’t know if we’re going to be heading into that massive of an event, but there are lessons there. A lot of people want to go, “Well, what’s CO2? What’s the big deal?” It’s 400 parts per million. That’s a lot.

As you said, there is sort of a more optimistic way of looking at mass extinction, because there are some positive potential outcomes…

In an extinction event, you’ve got a new playing board. I went up to Mt. St. Helens and looked at the land around that volcano. They’ve actually separated a portion of the volcanic area as a natural experiment to see how life would come back. Nature actually does a pretty fabulous job pretty quickly.

I looked also at after the eruption of Krakatoa — we’re talking the late 1800s, the whole island was almost leveled and it knocked out islands all around it, just a massive explosion. And yet today, not only have plants returned to Krakatoa and existing remains in that area, but so has wildlife. In about 150 years; that’s pretty amazing.

There would be a resilience to nature if man could just be a part of nature and the natural environment, rather than trying to be the dominant force on Earth. I guess my take-home message of the whole thing is that we can’t start thinking of ourselves as the be-all and end-all of natural history. We’re just a dot on a continuum that’s been ongoing for 600 million years. We really need to get a better perspective of ourselves. We are not the most important thing on the planet. We won’t last forever. Nobody I talked to thought we would. You, I and Homo sapiens have a limited life span, but if we could slow down and pull back a bit and start acting a little bit more like a part of life on Earth rather than the whole reason for its existence, we might just last longer and enjoy what we have left.

I wonder if that could be a different way of framing climate change, and other problems humans are causing. We like to say that we’re destroying the planet, but if nature is resilient, it’s more that we’re destroying ourselves. Earth is more likely to recover than we are.

We need Earth. We need nature. New York needs the microbes in the soil and the roots of plants and trees in the Catskill mountains to clean its water. The eastern coast of central America needs the coral reefs, the mangroves and the salt grasses to deaden the force of the hurricanes and the large waves that come in. Nature is really important for insect control: the birds and the bats have a lot to do with controlling insects and they’re a really important part of pollination. Nature actually plays a role in the creation of oxygen. We get a majority of our oxygen from the rainforest and the plankton in the ocean. There are a lot of really important things that nature does for us that we don’t respect.

And the reasons why we should respect them are, in a lot of ways, selfish.

Yeah, we’re looking after our own health if we look after the health of nature.

You write about all these things that could potentially cause man to go extinct. Is there any, from what you’ve seen, that’s most likely to hit us first?

People talk about the principle driver being climate change, but I really think it’s population growth. I mean, in 1800 we had a billion people, and right now we have 7 billion — only 200 years later. We’re expecting to have 9 billion by the mid-century and 10 or 11 billion out there by the end of the century. This has just happened in our lifetimes: the big growth was after World War II in the United States. It’s the driving force, but we’re not looking at it, and I really believe that climate change would not be such a horrible problem right now if we only had 1 billion people on Earth. It’s something that we don’t want to look at. That’s even more taboo than climate change.

The argument goes that that’s the underlying factor driving climate change, and also driving the emergence of infectious disease, right?

Well infectious disease, Rick Ostfeld at the Cary Institute of Ecosystem Studies has been studying how Lyme disease comes up in New England and the Northeastern area. He points out that what we’re doing is by eliminating species, we’re actually producing an environment that is conducive to disease. An environment that has a multiplicity of species has different carriers of the disease, some being good carriers like rats and chipmunks, while others like possums are not such good carriers. Essentially, by having the full conduit of species and by having a multiplicity of species, we dilute the transmission of disease. That’s another selfish reason to protect the rest of nature.

I was really intrigued by the part of the book where you talk about different scenarios for mankind’s future — you know, if we don’t go extinct, some other things that might happen. Did anything strike you as the most likely, or perhaps most enticing, scenario?

I had a variety of scenarios in the book. And you know, I’m kind of a nature lover, so the path that goes on after man actually sounds kind of good to me. There are a couple of tar deposits under Los Angeles where they have little representatives of what life was like 30 thousand years ago to what life was like 40 thousand years ago. People talk about what life was like before the coming of the Europeans, and I started running into more people who liked to look at life before the arrival of man. It’s really exciting to me, that L.A. could be a basin of mastodons and camels and saber-toothed tigers and things like that.

Then there’s the Palmyra Atoll, which exists between Hawaii and Australia, so it’s way out in the middle of the ocean, and it’s unoccupied. Today the Nature Conservancy actually protects it. It’s remarkable. If you run around with science journalists, everyone wants to go there, just to see what life would be like without the influence of man. I’d like to see that.

There’s also the idea of what could life be like if man continued? What would the next species of humans be? Genetic manipulation could produce a race of super-humans that would basically want to isolate themselves from us. That’s a possibility. Then there are more fanciful things. I visited Oxford professor Nick Bostrom — he had the idea that at some point, man is going to start uploading his mind into a computer. It would be based on the fact as you reach the end of life, there’s a way to extend it, the idea being that you could live on as either a robot or as an avatar in a virtual world. Second Life, where huge amounts of people spend 10 or 20 hours a week in virtual lives, is an example of that already. James Barrat with “Our Final Invention” talked about what could happen if A.I. could replicate itself or learned how to advance its intelligence on its own, and how soon it would be before it passed us.

Another big possibility is if we go to Mars. If we were to go to another planet — and I chose Mars because it’s the most likely — living there for a period of time would be conducive to developing into another species. You have one-third of the gravity you have on Earth plus you have to make your own oxygen. There’s high UV radiation and this can cause disruptions to the genetic system. These are all good ways to become another species. It doesn’t go beyond a few generations of life on Mars before you could have the definition of another species. It isn’t without reason that in a few generations, that could create another species of man that might come down and visit us again. And whenever we have the next species, part of Darwin’s idea is that one species develops out of the next one and then outcompetes the other.

You seem to feel that the most optimistic futures don’t include man. Can you see any role for humans as we are now — perhaps if there were just fewer of us?

Yeah, that would help. Toward the end of the book I talk about the fact that there have been some examples of that, some major changes. We did get rid of slavery. That was a major thing; we needed a major change of thought. Women’s suffrage is a major change in the way society runs. Today, our growing acceptance for homosexuality could also another change in society. So we could have a major change in society, but what it requires of us is to pull back from the dinner table, essentially. There can’t be as many of us. Maybe we could have 1 billion, and I don’t know how that happens.

That’s the next question.

I think if we looked at it more often and if we studied it, if that entered the conversation, that would be a really good thing. And there’s promise in that. If we start really addressing population, whatever that means, and we actually start discussions of it, that would be a good sign.

Lindsay AbramsLindsay Abrams is a staff writer at Salon, reporting on all things sustainable. Follow her on Twitter @readingirl, email  …………’


Hillary Clinton wishes to stop all Wild Life Crime

Hillary Clinton Helping to stop Wild Life Crime

Here we have Hillary Clinton the USA Secretary of State supporting the WWF campaign on Wild Life Crime.

Please take time to thank Hillary Clinton for her support. To do this click this link Support Hillary Clinton

A great ally in herself with the USA behind her, this is a commitment that should be undertaken by the world at large, countries as well individuals in each country.

For one reason or another the human species has taken control of the worlds resources for its own ends and if taken to its extremes could eventually lead to the total extinction of all living matter, humans , animals, vegetation, etc.

Any use of a resource will have some effect on other resources, some good, some bad, some seen, in effect, immediately, some only after many years, possibly many generation hence.

Resources are important to all, not only humans.