Originally Posted by ZillionGuppies
What I said about people's perception of atmospheric CO2 was germane to this thread and not an "unneeded shot" The interaction that precipitated this thread was a conversation about CO2 levels.
Nobody ever bothers to put into perspective numbers like 400 ppm atmospheric CO2. All anyone ever reports is: "atmospheric CO2 levels are higher than ever..." Context matters. Reporting numbers without context is decidedly unscientific.
"BTW, how many humans were around when atmospheric CO2 was 4000 ppm?" To the best of my knowledge, no humans were around at the time. And all the animals got along just fine.
Yeah, but they were really different animals.
The organisms on the planet now are adapted to survive with a certain climate. If that climate changes faster than natural selection can keep up, mass extinction will follow. For example, if atmospheric CO2 levels continue to rise, the amount of dissolved CO2 in the ocean will go up, increasing acidity and leading to the extinction of all if not most shellfish, coral, and organism which depend on shellfish and coral, as well as organisms which depend on organisms which depend on shellfish etc. As average global temperature goes up, ecosystems around the world will fail. When the delicate balance between weather, climate, and ecology is disrupted, the world will experience drought in some places, floods in others, and agricultural production will be severely reduced.
For the record, no one ever says "CO2 levels are higher than they've ever been". I have never heard that. What journalists, scientists, and activists DO say, is that "CO2 levels are higher than they have ever been in recorded history". That does not include "100 million years ago", so cool your outrage.
Just to give you an idea of how long ago 100 million years ago was.
Whales only evolved 50 million years ago.
Flowing plants evolved 150 million years ago.
This is what things looked like 100 million years ago:
It might be hard to notice, but none of the things in that illustration exist anymore.