Lee Kump, Dean of PSU's College of Earth and Mineral Sciences (we filmed this back when he was merely a professor in Penn State's Department of Geosciences), has been studying ancient climates based on the evidence left behind in marine sediments for most of his career. Watch this video below to see him explain some of his hypotheses about the end-Permian mass extinction and to hear more about his research.
Video: Interview with Lee Kump - Part One (5:37)
Interview with Lee Kump - Part One
- Click here for the transcript of Interview with Lee Kump - Part One.
DR. LEE KUMP: I'm Lee Kump. I'm a professor of earth sciences at Penn State and a paleoceanographer. Paleoceanographer is kind of strange term. I'm a person who studies ancient oceans. And this is something I came to as a graduate student. I was always interested in the oceans, and my graduate training is in oceanography. But my undergraduate work was in geology. So I had these dual interests of the oceans and the geologic record, and I was looking for something that would bring these two things together, and I found paleoceanography.
So it's a study of ancient oceans, looking at their record as they are preserved in sedimentary rocks. So I study intervals of Earth history that are particularly interesting, we look for rocks that are of that age, we investigate them, and then we try to put that in the context of how the oceans, and the atmosphere, operated as a system, and how they might have behaved during these interesting intervals.
So we're focusing on a particularly interesting and controversial interval of Earth history. It's the end-Permian mass extinction. So this was an interval, a brief interval, of geologic history some 250 million years ago, that represents the largest mass extinction of all time. It's estimated that as much as 95-99% of all species on the planet went extinct during this interval of time. And so it's a major event in the history of the planet. And it's an extraordinary event. And so we're certain that it was the result of very extraordinary causes.
There have been a number of hypotheses that have been proposed, including asteroid impacts, massive volcanic eruptions. We've been focusing on the state of the ocean at this interval of time because there's good evidence that the ocean then, was very different than what it is today. Today, if we were to go down in a submarine, and go down into the deep ocean, we'd find an environment that was cold and was oxygen-rich. And so it's an environment that supports diverse types of life that are like ourselves, needy of an oxygen-rich environment.
When we look at the evidence from the Permian ocean, we find out that the deep ocean was much warmer than it is today, and it was devoid of oxygen. And so it was a very different, sort of hostile world, from the perspective of animal life. And what's really unusual about the evidence for the Permian ocean is that it wasn't only free of oxygen, but it had a poisonous mixture of hydrogen sulfide and carbon dioxide that would have been instantly fatal to any organism like ourselves, like fish, or even marine plants like algae, exposed to that ocean.
What we're investigating is the possibility that this poisonous ocean of the late Permian migrated from not just being in the depths of the ocean, but migrated up toward the surface and poisoned all the life at the surface. And, just as importantly, as this hydrogen sulfide rose to the surface it, as a gas, escaped into the atmosphere. I think we're all familiar with hydrogen sulfide. It's that characteristic smell of rotten eggs. What we think happened at the end of the Permian, is that this poisonous ocean rose to the surface. Hydrogen sulfide, as a gas, escaped into the atmosphere and wafted up onto the continents in big clouds of poisonous gas wiping out life on land.
One of the great mysteries of the Permian extinction is that it was a mass extinction not just in the oceans, but on land. And so we're looking for some connection that links the ocean extinction to the land extension. We began studying the Permian ocean, came to realize that it had this toxic mixture, and then with some simple modeling-- computer modeling calculations, found out that that hydrogen sulfide could escape to the atmosphere and create toxic conditions in the atmosphere as well.
So this is, of course, quite controversial. There is some evidence for it, but not overly convincing evidence. And other people have their own pet theories about what c caused this. We've had quite vigorous arguments at national meetings about this issue. One idea is that the buildup of hydrogen sulfide in the atmosphere, this is our particular idea, would lead to chemical reactions that would destroy the ozone layer. And we've demonstrated that with a computer model.
Other people link to that event to massive volcanism. And so there are these interesting clues from the geologic record that the environment was quite different. And one thing that we know, and the dating now of those rocks as has demonstrated pretty much beyond the shadow of a doubt, at the same time the organisms were dying all over the planet, massive volcanoes were erupting in Siberia. These are called the Siberian Traps, and there are still voluminous basaltic rocks that have been preserved on the Siberian plateau that were deposited at this instant in geologic time. So any theory for the cause of this mass extinction has to include those volcanoes. This is one of the most massive volcanic eruptions of all time.
Video: Interview with Lee Kump - Part Two (6:44)
nterview with Lee Kump - Part Two
- Click here for the transcript of Interview with Lee Kump - Part One.
[MUSIC PLAYING] LEE KUMP: Well, the volcanologists, for a long time, argued that the volcano must have been the cause of the Permian extinction and environmental consequences resulting from this massive volcanic eruption. The oceanographers, the paleoceanographers, have been looking at the ocean. They see an anoxic ocean. They see evidence for hydrogen sulfide. That must have been the cause.
What we're trying to do, actually, with our computer models is to bring this all together, to synthesize these into a consistent story of environmental change. And remember, this is perhaps the singular event in earth history. This set the stage, in some regards, for the evolution of the dinosaurs. This was just before the dinosaurs. And perhaps the biotic change that happened at this time allowed the dinosaurs to take over during the ensuing Mesozoic.
And then, the asteroid hits, it wiped out the dinosaurs, and mammals evolved. And so there are these events in Earth history that seem to be critical to the path of evolution. So it's an important question. And a lot of people are working on it, and they're working on it from their own specialties and their own perspectives.
One of the things that we do as geologists is to look for modern analogs-- places that we can go today that we think are like what the environment we're studying in the ancient rock record was like back then. And so our interests are, of course, these hydrogen sulfide-rich marine environments. And the most obvious place one could go to study that in the modern world is the Black Sea, but that's very inaccessible. Fortunately, here at Penn State, we have a lake nearby. It's actually near Syracuse, New York. But it's a lake that we think is much like what the Permian ocean was like back then.It has a layer at the top of the lake that's well mixed and oxygenated. In fact, people swim there and fish there. It's a state park. But lurking down below this upper 60 feet of well-oxygenated water is a poisonous mixture of this hydrogen sulfide-rich water. And so we've been going there. We study this by going scuba diving, so we have divers who dive down into this environment, myself included, collecting samples, not just of the water, but of the organisms that live right at this interface between oxygen-rich water and hydrogen sulfide-rich water below.
So we dive right to this interface. We don't spend much time below it, because it's poisonous and prolonged exposure to hydrogen sulfide-rich water can be fatal. So we dive down to this layer, maybe dip down just below to collect some samples very quickly, and we're looking at the chemistry of this water and the organisms that are living there. And we're looking for organisms in particular that produce compounds that we find in the rock record associated with the Permian mass extinction.
So it turns out that organisms that live right at this interface between poisonous and non-poisonous water produce compounds that are preserved in sedimentary rocks for up to billions of years. And so we're looking at these modern organisms. We're extracting these chemical compounds from-- we're analyzing them and then we're comparing them as a fingerprint, as a sort of a chemical fossil, of what was living in the ocean at the time.
These organisms are bacteria. They don't leave fossils like we're used to thinking of, shells or bones. What they leave are distinctive organic compounds that we're trying to relate from the living organism to these ancient fossils. And once we can do that and we can look at their distribution in these modern environments, then we'll have a much better picture of the conditions in which they were thriving in this Permian ocean.
One of the other interesting things about this interval of time is that the oceans became very similar to what we think they were billions of years ago. And so the Permian, 250 million years ago, was a time period in which the oceans were transformed into what we think the oceans were like a billion years ago. And we know that a billion years ago, the types of organisms that thrived in this poisonous, oxygen-free environment, generated a type of rock that is known as a stromatolite. And in fact, this is a stromatolite here.
It's a layered rock that forms. This is a cross-section through one. If you could imagine what this would look like, it would be like a head of cabbage. And its layer upon layer upon layer of a bacteria that are growing up off the seafloor forming a mound. It's called a stromatolite.
And in this case, this rock has been truncated as we can see the inner laminations of this. This is formed entirely by bacteria, and it forms in environments today in very extreme environments, but it was much more abundant in the distant geological past such as in the Precambrian.
What we find out is that right after the Permian extinction, stromatolites come back. So there's a reappearance of this very ancient life form-- something that we usually associate with the Precambrian billions of years ago. At the end of the Permian, right after the mass extinction, these bacterial communities come back and thrive.
And so this is another piece of evidence that the Permian ocean became such an inhospitable place for advanced life forms that it reverted back to an earlier state that we think was more associated with the Precambrian in which bacteria thrived.
n addition, here is a press release about Lee's hydrogen sulfide hypothesis:"Hydrogen Sulfide, Not Carbon Dioxide, May Have Caused Largest Mass Extinction," ScienceDaily(Nov. 5, 2003)
Kump, L.R., A. Pavlov, and M.A. Arthur, 2005, Massive release of hydrogen sulﬁde to the surface ocean and atmosphere during intervals of oceanic anoxia, Geology 33, 397–400.