Did CO2 Starvation Cause The Extinction Of Dinosaurs?

By Karl J. Hansen, klimabedrag.dk

The extinction

The large dinosaurs appears to disappear from the face of the Earth about 65 million years ago.  We have a few survivors left, like the crocodiles, but all the survivors are smaller than dinos 65 million years ago.  A common believe is that this mass extinction was caused by a huge meteor.  Assuming this theory is correct and that the result was widespread destruction of tall plant life all over the globe, this would finally result in mass-extinction of most tall animal life.

Big plants equals big life

Although the temperature remained very stable for millions of years before and after the end of the dinosaur era, the CO2 level fell below  1000ppm (0.1%).  The question I ask: Did the CO2 level fell to a level where plant life could not regain and sustain the mass and size needed for the big fellows.

No correlation

All of the Triassic, Jurassic and Cretaceous periods had CO2 levels way above 1000ppm (0.1%).  During these periods, there was absolutely no correlation to the temperature.  Even if there had been, it would be of no interest, as the temperature has the leading role over CO2 and not visa versa.

Worship the current trend

Assuming that high temperature, high O2 and high CO2 concentration is needed to sustain large dinosaurs, we should appreciate the trend we have had since the Little Ice Age.  It would be mature to hope for a significant increase in CO2 in the atmosphere to at least 1000ppm (0.1%).  If the Sun would help us to somewhat higher temperatures, this would be an additional benefit.

Focus on the big picture

The climate system is very complicated, even for top climate scientists, and to assume thermal runaway and future impossible living conditions, by comparing to a geological mediocre period, does not make sense.  We have data material going a relative long time back in the geological history and we should be clever enough to use these data and try to avoid too much cherry-picking in the attempt to prove the hypotheses we make.

The opposite theory

In the article "From Brachiopods To Bivalves: Did CO2 Cause The Worst Extinction In Earth's History?" they attribute Rise in CO2 to result in the huge Permian-Triassic extinction.  However, they do not explain that 200million years later the next mass extinction appears when CO2 is falling drastically.  They further do not explain why life on land was thriving better than ever since, during this period of many-fold more CO2 than we have today.  They further state the unsupported idea that CO2 is driving the temperature.  They either come to this assumption because the IPCC and Al Gore says so or they got focused on the correlation between temperature and CO2 252million years ago - cherry-picking again.  They "forgot" to look at almost any other period in history and they "forgot" their basic physics lessons about the fact that as the oceans heat up, they can contain less and less CO2.

Conclusion

It is a really long time since we have been walking with the big dinosaurs.  Seen from a logic viewpoint, the large animals were adapted to tall and rich plant life.  Size and richness of plant life depends mainly on CO2, all else even.  It is likely that there was too little CO2 in the atmosphere, after whatever catastrophe caused the death of the large dinosaurs, for the plants to recover to a level that would sustain large animals again.