quote: Ah, but the Devonian event wasn't due to species extinction, but rather a simple decrease in the rate of speciation, stretching over several million years.
quote: though this is not true for the Permian event, in which both species count and biomass decreased
quote: Low origination contributed more than high extinction to the marked loss of diversity in the late Frasnian
quote: Then you'll be pleased to know that the US actually has a higher level of forestation today than it did in the year 1900. Today, more of the US is covered in trees than was 100 years ago.
quote: Historically, atmospheric oxygen has never varied substantially
quote: I see population and deforestation as far more serious threats to producing global warming than industry.
quote: Yet he brings up a valid point: where did the the CO2 come from?
quote: The largest continuous volcanic eruption on Earth – known as the “Siberian Traps” – had been pumping out CO2 for about a million years prior to the Permian-Triassic mass extinction
quote: The thing that has always bothered me about GW proponents is that one moment they are talking about climate changes in the past, and the next moment blaming human activities for current Climate Changes, without ever stopping and thinking about what they just said: the global Climate has changed numerous times in the past and would have changed in the future even if humanity had never existed.
quote: First of all, this is not an article about a study on modern GW, so why are you so threatened??
quote: Also, during this period in the Paleozoic, their were far less large land animals (like 6 billion humans) than there are today.
quote: Secondly, you appear to think that is not important to learn from historical events. This is a very foolish perspective, from a purely societal perspective and from a scientific perspective.
quote: We are also concentrating pollutants, such as mercury, sulfur, benzene, and ammonium into deposits and emissions many more times more concentrated than those found in nature. This is the dangerous thing about CO2 emissions and pollution in general--its the concentration, not the substances.
quote: Volcanic activity releases about 130 to 230 teragrams (145 million to 255 million short tons) of carbon dioxide each year.[7
quote: First of all, a 1% CO2 level doesn't "lead to carbon dioxide poisoning". Our own BREATH has a CO2 level of 4.5%, and even that isn't toxic unless breathed over a lengthy period....which explains why you can breath in and out of a bag for short periods without harm.
quote: A 3% level (the minimum level which can cause any sort of respiratory problems) is a level of 30,000 ppm.