Climate change What were the carbon dioxide levels prior to the last ice age?

Source Quora by Roger Fjellstad Olsen,

For 800,000 years before about the year 1850 the amount of CO2 in the atmosphere varied between about 170 and 280 ppm. After 1850 that level started to rise due to anthropocene (man made) changes in our enclosed space ship planet system. That level is now about 414 ppm.

• The increase in CO2 from 280 ppm in 1880 to 409 ppm in 2019 is a 46% increase of Co2(128/280*100) and 31.4% of the atmosphere CO2 is thus from humans (128/408*100).

IT’S THE HIGHEST CO2 LEVELS FOR 56 MILLION YEARS.

• Present day CO2 or temperature levels are not unique, but the speed of these changes have never been seen before. Changes that typically take millions of years are now happening in a century.

The fact that CO2 levels and temperatures were higher millions of years ago is irrelevant to whether people living today will be negatively impacted by recent high levels.

because,

The effects of today's RAPID global warming are felt by societies and existing ecosystems adapted to the Holocene climate in OUR TIME - NOT the climate and CO2 levels that existed hundreds of thousand or millions of years ago which gave ecosystems time to adapt.

“The data show the present idea that rises in CO2-levels that used to take millions of years, are now happening in a century”

Over Earth's history, there were times where atmospheric CO2 was higher than current levels. Intriguingly, the planet experienced widespread regions of glaciation during some of those periods. Does this contradict the warming effect of CO2?

No, for one simple reason. CO2 is not the only driver of climate. To understand past climate, we need to include other forcings that drive climate.

Also, before SUVs, volcanos and flood basalt events could release huge amounts of CO2.

“In the past, when CO2 levels rose higher than they are today, it often happened over millions of years and the various forms of life on earth were able to evolve and adapt. But there were a number of times when CO2 levels and temperatures rose as quickly as they have risen in the last 100 years. These changes had profound consequences leading to mass extinctions. For example, 252 million years ago there was a rapid rise in CO2 due to a series of volcano eruptions, and global temperatures rose 11 deg. C wiping out 95% of all species on earth.”

Last 10 000 years:

Total human carbon dioxide emissions could match those of Earth's last major greenhouse warming event in fewer than five generations, new research finds. A new study finds humans are pumping carbon dioxide into the atmosphere at a rate nine to 10 times higher than the greenhouse gas was emitted during the Paleocene-Eocene Thermal Maximum (PETM), a global warming event that occurred roughly 56 million years ago.

Earth may be 140 years away from reaching carbon levels not seen in 56 million years

Fossil algae reveal 500 million years of climate change | Geology Page

Our impact is almost unreal:

• Yes, the climate has changed before. But warming has never hit the entire planet at once the way it is now, new research shows. When was the last time the planet had nearly 8 billion people burning fossil fuels warming the planet out of its natural cycles?
• The climate hasn't changed much since we settled into towns, invented plumbing, and started calling ourselves civilized.
• Thus it’s dramatic how fast we left the stable temperatures that allowed the development of agriculture and human civilization to arise.