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Even with all of the recent scandal surrounding the purveyors of climate change pap, many in the “news media” continue to crank out party-line articles blaming all of Earth’s ecological woes on humanity. After decades of trying to alarm the public over a human caused “sixth mass extinction” and more recently, dwindling diversity, some in the media just can’t let go of AGW as the root of all evil. A perfect example of this appeared recently in the font of misinformation that is Yahoo News. Blaming every human activity from hunting to climate change, science writer Jeremy Hsu has once again raised the specter of that old shibboleth, the Anthropocene Epoch. This is all a part of a developing trend to elevate falling species diversity to crisis level, mainly because the world’s eco-activists need a replacement issue for climate change.

In the Yahoo Canada News article “Mass Extinction Threat: Earth on Verge of Huge Reset Button?,” it is as though time has stood still. The same old tired arguments, the same reflexive blame-humanity-first mentality pervades a piece of journalistic drivel that could pass for IPCC propaganda. From the first paragraph, Hsu proclaims his obeisance to the climate change party line:

Mass extinctions have served as huge reset buttons that dramatically changed the diversity of species found in oceans all over the world, according to a comprehensive study of fossil records. The findings suggest humans will live in a very different future if they drive animals to extinction, because the loss of each species can alter entire ecosystems.

After inadequately setting the scene in his first paragraph, Hsu wastes no time in linking extinction and anthropogenic climate change. Here is the second paragraph of the “news” article:

Some scientists have speculated that effects of humans – from hunting to climate change – are fueling another great mass extinction. A few go so far as to say we are entering a new geologic epoch, leaving the 10,000-year-old Holocene Epoch behind and entering the Anthropocene Epoch , marked by major changes to global temperatures and ocean chemistry, increased sediment erosion, and changes in biology that range from altered flowering times to shifts in migration patterns of birds and mammals and potential die-offs of tiny organisms that support the entire marine food chain.

That’s right, humanity is as dangerous as all of the natural disasters that caused mass extinctions in the past. We are raising temperatures, increasing erosion, messing up ocean chemistry and destroying the entire food chain! The real tip-off that Hsu is an eco-alarmist is the mention of the Anthropocene, an unrecognized geologic time period dreamed up by green alarmists. For background information on the Anthropocene see “Welcome To The Anthropocene” and “A Brave New Epoch?

Hsu is trying to report on the findings of a real journal article that appeared in the September 3, 2010, issue of Science, and he is evidently incapable of correctly interpreting the results without the ingrained bias of the news establishment coloring his assessment. To understand the article, “The Shifting Balance of Diversity Among Major Marine Animal Groups,” by paleobiologist John Alroy, one needs a little background information about mass extinctions and species diversity over the past half billion years or so. We examined the history of life and mass extinctions in Chapter 6 of The Resilient Earth:

Since the advent of complex life on Earth there have been five major mass extinctions. Recently, evidence has been found for another extinction during the early-Cambrian, 512 mya. This event is so far in the past that not much is known about its causes, but it is an indication that major extinctions have been happening for half a billion years.

The most famous extinction is also the most recent, the KT or end-Cretaceous Extinction, 65 million years ago. The subject of many TV shows, most people know the story of the asteroid that killed the dinosaurs. What most people don’t know is that, along with the dinosaurs, 85% of all species on Earth vanished during that time. Because it was the most recent extinction event, scientists know more about the KT event than the other great extinctions. Here is a summary of the six major extinctions:

  • Early-Cambrian (512 mya): earliest recognized mass extinction eliminated 50% of all marine species.
  • End-Ordovician (439 mya): 85% of marine species disappeared, including many trilobites. Second largest marine extinction with 60% of marine genera and 26% of marine families.
  • Late-Devonian (365 mya): 70-80% of animal species went extinct, including many corals, brachiopods, and some single-celled organisms. Accounting for 57% of marine genera and 22% of marine families.
  • Permian-Triassic (251 mya): extinction of 96% of marine species, including all trilobites and many terrestrial animals—Earth’s biggest extinction.
  • End-Triassic (199 mya): extinction of 76% of species including many sponges, gastropods, bivalves, cephalopods, brachiopods, insects, and vertebrates. Mostly affecting ocean life killing 57% of marine genera and 23% of marine families.
  • KT or end-Cretaceous Extinction (65 mya): 80% of all species on Earth vanished, most notably the dinosaurs. Eliminated 47% of marine genera and 16% of families.

The causes of these natural catastrophes are varied. Ice ages may have played a major role in several. There is evidence that fluctuations in sea level was the primary cause of the end-Ordovician extinction, which mostly affected marine life This is unsurprising since, during the Ordovician, the majority of life was found in the seas. Joseph Sepkoski called this extinction one of the two or three worst extinctions of the Phanerozoic, noting that generic diversity dropped to about the level of the pre-early-Ordovician proliferation.

Many families, genera and species vanished in the end-Ordovician extinction.

The late-Devonian mass extinction was a prolonged marine crisis spread over 20-25 million years and punctuated by 8-10 extinction events. Because it most severely affected warm water marine species, leading many paleontologists to attribute the Devonian extinction to an episode of global cooling, similar to the event which caused the late-Ordovician mass extinction. Glacial deposit evidence, found in what is now Brazil, points to a glaciation event on the supercontinent Gondwana during this period. Much like the late-Ordovician crisis, global cooling and widespread drop in sea level may have triggered the late-Devonian crisis. There are suggestions that a meteor impact could be the cause, but the evidence is inconclusive.

The Permian-Triassic Extinction is widely considered the worst of all the major extinction events, killing off an estimated 95% of terrestrial life. From rock layers in Texas and Utah comes evidence that this extinction came in two parts, called extinction pulses, separated by about 10 million years. Either of the two events alone was worse than the KT Extinction that killed off the dinosaurs. Between the two events, 82% of marine genera and 50% of all marine families were extinguished. In earlier chapters, we mentioned the extent of damage this extinction inflicted on Earth’s creatures, but the most telling feature was the length of time needed for life to recover. Well into the Triassic, as many as 20 million years later, the effects were still felt. Geologists and paleontologists consider this extinction a major turning point in the history of life on Earth.

Causes put forward for the biggest of all extinctions pretty much cover the entire range; climate change, sudden release of CO2 or methane, volcanoes and an asteroid strike have all been suggested. Douglas Erwin, in his excellent book “Extinction,” covers all the theories in detail, and finds no single explanation fully satisfying. He has suggested what he calls the “murder on the orient express” theory, a combination of several or even all of the causes listed above.

The Manicouagan impact structure seen from space. NASA/JPL

The end-Triassic Extinction doesn’t get much press, coming on the heels of the worst ever extinction, and before the dramatic meteorite impact that extinguished the dinosaurs. At least two impact craters have been found from around the time of this extinction. One is in Western Australia, where scientists have discovered the faint remains of a 75 mile (120 km) wide crater. The other is a 212 million year old crater in Quebec, Canada, forming part of the Manicouagan Reservoir. The Manicouagan impact structure is one of the largest impact craters still visible on the Earth’s surface, with an original rim diameter of approximately 62 miles (100 km).

Others have suggested that a sudden, gigantic overturning of ocean water created anoxic conditions causing the massive die-off of marine species. About 23% of terrestrial families also died out,v so there is doubt that such an aquatic event could account for all of the vanished species. There is recent evidence that the end-Triassic experienced an extended period of massive volcanism called the Central Atlantic Magmatic Province (CAMP). This event is associated with the breakup of the super-continent Pangaea and the appearance of a giant rift that eventually formed the basin of the Atlantic Ocean. Carbon isotope anomalies at the Triassic–Jurassic boundary reflect the effects of volcanically derived CO2, possibly combined with methane release from gas hydrates due to global warming. This makes volcanoes the current favorite trigger for this extinction.

The final major extinction in our list is the KT or end-Cretaceous Extinction. We have already mentioned, in Chapter , how Luis and Walter Alvarez, having found an unexpected spike in iridium content in sediment from the Cretaceous-Tertiary boundary, hypothesized that this extinction was due to an impact with an extraterrestrial body. They later found evidence of that impact in the Yucatan peninsula of Mexico. That evidence came in the form of a crater between 105 and 185 miles (170 to 300 km) in diameter.

The KT extinction killed a lot of strange critters.

Impact models estimate the object was between 6 and 10 miles (10-15 km) in diameter, and would have ejected 25,000 cubic miles (100,000km3) of rock and debris. Such an impact would have directly killed every-thing for thousands of miles, and also triggered earthquakes and tsunamis. As bad as these effects were, the real killing was caused by ash and vaporized rock that filled the atmosphere, which formed dust clouds that blocked the Sun. These clouds are thought to have lasted many months, stopping plant growth and chilling the planet.

A summary of the major extinctions is shown in the illustration below, depicting diversity in terms of marine families. Starting with the newly discovered early-Cambrian event, the extinctions are numbered from zero. This is to avoid changing the normal numbering of the “big five” extinctions, as they are widely called in the literature. The figure is based on work done by University of Chicago paleontologist Jack Sepkoski in the early 1980s. Sepkoski categorized marine animals into Cambrian, Paleozoic, and Modern evolutionary faunas on the basis of shared curve shapes. This categorization has served as a benchmark for evolutionary research at the Phanerozoic scale for a quarter of a century.

Marine diversity during the Phanerozoic. After Sepkoski.

I have used this figure before, both in The Resilient Earth and in other blog posts, but the story it tells is worth repeating. The three differently colored areas of the graph represent the numbers of families belonging to the Cambrian, Paleozoic, and Mesozoic periods. As you can see, the early Cambrian life forms started being superseded by the intermediate forms of the Paleozoic prior to the end-Ordovician Extinction and had almost vanished by the late-Devonian. The life-forms characteristic of the Paleozoic undergo a major decline until the Permian-Triassic Extinction, and some related species linger to this day. But notice the rise in diversity after each extinction event—after each horrible, life-ending catastrophe, life bounces back stronger and more diverse than ever.

The double blow of the Permian-Triassic followed by the end-Triassic cleared the way for the rise of the dinosaurs and, eventually, mammals. Without the KT extinction mammals would never have risen to dominate life on the land and consequently, humanity would never have evolved. It may well be that after each successive extinction life recovered more energetically because is was starting from a more evolved ecological base. Whatever the reason, the trend is clearly evident.

Alroy, once a student of Sepkoski’s, is not the first to revisit the macro-evolutionary history of the Phanerozoic. The fossil record is patchy and long-term evolutionary principles are still hotly debated, leaving much room for new analyses and interpretations. Alroy and colleagues (including Sepkoski) created the Paleobiology Database (PBDB), a compilation of data from nearly 100,000 fossil collections that continues to grow. Alroy’s article is an updated analysis of the contents of the PDDB. Alroy was not looking for a sixth extinction marking the beginning of an Anthropocene era—he was trying to answer the question whether global mass extinctions are just short-term diversions in life’s preordained course, or if they send the evolution of life in wholly new directions.

Alroy’s analysis suggests that the future is inherently unpredictable, that what comes next cannot be predicted from current conditions, no more than a mid-Cretaceous observer could have guessed that a few tiny mammals would someday occupy every ecological niche then ruled by reptiles. As he states in the Science article:

These findings refute the idea that diversity trends, including successive replacements of groups, are a function of exponential or random growth interrupted by mass extinctions. Such arguments only ever seemed plausible because biases in older data sets, including the greater quantity and quality of data in the Cenozoic, created the appearance of a steep post-Paleozoic increase. These biases also obscured large, rapid shifts in diversity such as the Cambrian explosion and the mid-Jurassic radiation.

Sepkoski’s model impled that average diversification rates are a good predictor of long-term success. Alroy has found that this is not so, a conclusion that Sepkoski had also come to in his later work. Alroy offers this updated diversity plot for the Phanerozoic.

Marine diversity during the Phanerozoic. After Alroy.

While it is true that Alroy uses the term “current global crisis” in his article’s abstract, that is not what the article is about—it is about how extinctions redirect the course of evolution. Nowhere in the article does he identify human induced climate change as the cause of the “crisis.” Alroy certainly adheres to the environmentalist party line by mentioning “today’s extinction crisis” but in the summary paragraph of his paper he offers up this more detached scientific conclusion:

Global diversity should rebound from today’s extinction crisis within roughly the equivalent of a geological period. However, it is not possible to predict changes in taxonomic composition, which are more ecologically and evolutionarily important than total counts of taxa. The most severe extinctions also have unexpected impacts on the relative abundance of closely related groups, the shape of species-abundance distributions, and patterns of epifaunal and infaunal tiering. Thus, it would be unwise to assume that any large number of species can be lost today without forever altering the basic biological character of Earth’s oceans.

There is nothing unexpected here. If humanity manages to kill off a large number of species through intent or neglect the future course of evolution may be changed. Certainly, our hunting of whales to near extinction is not an act for our species to be proud of. If we do drive whales to extinction the future of life in the ocean will undoubtedly be changed. But the important point is that global diversity should rebound if we stop destroying natural habitats. Given half a chance nature will bounce back as it has in the past.

Alroy’s conclusions are not being accepted at face value by the scientific community either. In an accompanying perspective article, paleontologist Charles Marshall, of the University of California Berkeley, notes that Alroy’s statistical methods must still be reviewed by the paleobiology community. The PBDB, as large as it is, is undoubtedly incomplete in ways yet to be discovered. “There will be no immediate consensus on the details of the pattern of diversity,” he wrote.

“How today’s extinction crisis – species today go extinct at a rate that may range from 10 to 100 times the so-called background extinction rate – may change the face of the planet and its species goes beyond what humans can predict,” Hsu concludes in his Yahoo article. There is an important difference between species diversity being limited by all ecological niches being filled and diversity being wiped out by a sudden ecological calamity—normal competition for habitat is far less likely to cause extinction than the oceans turning anoxic or a large meteor striking the planet. No reasonable person can equate mankind’s current impact on species diversity with the major extinction events in the past.

The claim that we are forcing extinctions at 100 times the “normal” rate is not backed by sufficient evidence. All of this diversity analysis is based on what has been found in the fossil record—it is neither complete nor conclusive. Fossil records are notoriously sparse and spotty; whole species may have come and gone from Earth without leaving a trace for paleontologists to puzzle over. Science is even unsure how many species are present on Earth today, keeping track of diversity in the distant past is even more uncertain.

Using cute animals to spread green propaganda is part of the scam.

It is right and reasonable to be concerned with preserving nature in today’s modern, industrialized world. Man wields greater destructive power than any previous species and does not have a good record of using that power wisely. However, H. sapiens cannot even come close to the power of uncaring nature. Comparing humanity’s impact on nature to mass extinctions in the past requires a mixture of half hubris and half ignorance.

The use of research like Alroy’s to promote an atmosphere of crisis over reduced species diversity is simply another example of the eco-activists creed—to get people to pay attention we must scare them to death. And using people’s natural empathy for cute, cuddly animals to spread feelings of self loathing is just another cynical ploy used by those who claim to love nature but actually hate humanity. With the global warming “crisis” dying a slow and painful death, the green crowd is looking for a new crisis to frighten the world with. Unfortunately for them, diversity is an even less supportable crisis than climate change.

Be safe, enjoy the interglacial and stay skeptical.

The Resilient Earth, 12 September 2010