Hypoxia and Medicine

Will human CO2 emissions cause another mass extinction event?

A 2008 study by Charlie Vernon - former Chief Scientist of the Australian Institute of Marine Science - investigated the 5 mass extinction events in the Earth's history over the past 500 million years. The study concluded "The five mass extinction events that the earth has so far experienced have impacted coral reefs as much or more than any other major ecosystem. Each has left the Earth without living reefs for at least four million years, intervals so great that they are commonly referred to as ‘reef gaps’" "primary causes of mass extinctions are linked in various ways to the carbon cycle in general and ocean chemistry in particular with clear association with atmospheric carbon dioxide levels. The prospect of ocean acidification is potentially the most serious of all predicted outcomes of anthropogenic carbon dioxide increase. This study concludes that acidification has the potential to trigger a sixth mass extinction event" "The oceans, including the ocean depths, respond slowly to atmospheric conditions, whether a temperature increase or a CO2 build-up, which means that the full effects of acidification will take decades to centuries to develop. Nevertheless, this is only a delay: the factors causing acidification will have irretrievably committed the Earth to the process long before its effects become anywhere near as obvious as those of mass bleaching today." "Ultimately—and here we are looking at centuries rather than millennia—the ocean pH will drop to a point at which a host of other chemical changes, including anoxia, would be expected. If this happens, the state of the oceans at the end of K/T, or something like it, will become a reality and the Earth will enter the sixth mass extinction. Another 1–3 decades like our last will see the Earth committed to a trajectory from which there will be no escape." http://iod.ucsd.edu/courses/sio278/documents/veron_08_coral_reefs.pdf So according to this study, unless we begin to reduce our greenhouse gas emissions within the next couple of decades, we may trigger an eventual mass extinction event. What do you think - will human CO2 emissions cause another mass extinction event?

Public Comments

1. There are at least two pernicious factors at interplay with regards to mass extinction: the first is human over-fishing in the worlds oceans where many species have been reduced with up to 90% in a few decades. The second is the increased acidity in the world's oceans that originates from the rising CO2 levels in the atmosphere. Unfortunately the acidification is happening way too fast for species to be able to adapt to the changes.
2. I don't see anywhere that says "CO2 WILL cause mass extiction". I see word like 'may or 'linked'. I can link fried chicken or cheeseburgers with the amount of child birth per year, does that mean less burgers = less birth? Fact is humans have been the primary causes of extinction in recent history. Not through GW, but through uncontrolled hunting, humans encroaching on animals habitat, introducing alien species, etc. Increase CO2 has a very positive impact on plant life. http://www.co2science.org/ If you wanna save species, CO2 should be at the bottom on the list of concerns.
3. The earth is getting colder. The scientists in charge of Global Warming made it up. Arctic ice is getting thicker. You might buy a parka.
4. I believe that technically speaking we are already at the start of one. The current extinction rate is something like 100 times the usual background rate. However, there will obviously be numerous factors contributing to this such as deforestation, over-fishing, aquatic pollution , etc. But saying that, it is very unlikely that climate change will not add significantly to this rate, especially if/when the tipping points are reached. The speed of change is simply to big for many organisms, particularly those in specialized niches to respond. As a side note, why are deniers even commenting on this question? Dana did not ask for your opinion on the truth of global warming. Why not keep it to a relevant question and let people who know what they are talking about answer this kind?
5. Volcanos are now putting out more then man could ever . Volcanos should be outlawed .
6. To some degree yes, but in what will be a parallel version of the Christian rapture only the believers in AGW will be taken. The rest of the unbelieving world will be left to develop new technologies and adapt to the new climate realities. The absence of AGW believers will of course make it easier because without them their will be much less hot air in the universe.
7. I hope Berkley goes first. Hey Dana which scientist is lying?
8. It was not an example of good science IMO. It was a good example of a very poor use of science by exaggerating certain theories and pushing acidification as an explanation. It is said some very strange things. It said there were no surviving corals after the extinction event yet obviously they did survive. Do these people actually think we can say there were no corals after the extinction event. Only a very small sample of rock is exposed of the proper age. We only can see a tiny percentage of outcrop, none above oceanic plates. When someone pretends to know more than they do, it is disturbing and evidence of psuedo-science. The article provided lots of evidence but their conclusions were not well founded in my opinion. They noted that species lost diversity as the KT boundary approached yet they seemed to suggest that acidification was likely responsible for lack of diversity afterward. First they need to explain the dwindling diversity that happened before the extinction event. When global warming alarmism started getting big money I noticed there were suddenly a bunch of theories attempting to rewrite previous extinction events. Suddenly dinosaurs, trilobites, and mammoths all died of climate change and acid. The problem is, the theory doesn't fit most of the evidence. They are making wild guesses and trying to fit the evidence into their theories. It is simply bad science IMO. It is activist science or trolling for AGW cash.
9. Only thru human flatulence.
10. Well within the possible, especially as modern aragonite-skeleton corals are quite different from the calcite-based corals of the mesozoic, and more vulnerable to pH drop. And as you say, this is the result of ocean acidification, rather than temperature as such, so even geoengineering (should that be possible) to reduce warming won't help any.
11. That reference is so misleading anyone who takes it serious has issues. It suggest a synchronous extinction is occurring within decades. Highly unlikely and without tangible proof, but alarmist protocol has always lacked credibility.
12. We're already in the midst of a 6th mass extinction. From the first link below: "There is little doubt left in the minds of professional biologists that Earth is currently faced with a mounting loss of species that threatens to rival the five great mass extinctions of the geological past, the most devasting being the Third major Extinction (c. 245 mya), the Permian, where 54% of the planet's species families lost. As long ago as 1993, Harvard biologist E.O. Wilson estimated that Earth is currently losing something on the order of 30,000 species per year -- which breaks down to the even more daunting statistic of some three species per hour." From the 3rd link: "If CO2 levels are allowed to reach 450 ppm (due to occur by 2030–2040 at the current rates), reefs will be in rapid and terminal decline world-wide from multiple synergies arising from mass bleaching, ocean acidification, and other environmental impacts." Several years ago I read a book by Terry Glavin titled, "The Sixth Extinction: Journey Among the Lost And Left Behind." He was referring to more than species, but it helped educate and enlighten me to the crisis at hand. Yes, we are leading the charge to a 6th mass extinction. Horrible, but true.
13. I firmly think that nature will devise another way to cull back the Human population before we reach that point.