The pre-industrial level of co2 in the atmosphere in ppmv is about?
No context provided
What is the commonly assumed value of the pre-industrial level of co2 in the atmosphere in ppmv?
290
No context provided
Based on more recent indirect data, what is the value of the pre-industrial level of co2 in the atmosphere in ppmv?
260-270
Carbon dioxide in Earth's atmosphere
https://en.wikipedia.org/wiki/Carbon%20dioxide%20in%20Earth%27s%20atmosphere
 On Earth, carbon dioxide is the most relevant, direct anthropologically influenced greenhouse gas. Carbon dioxide is often mentioned in the context of its increased influence as a greenhouse gas since the pre-industrial (1750) era.
Carbon dioxide in Earth's atmosphere
On Earth, carbon dioxide is the most relevant, direct anthropologically influenced greenhouse gas, often mentioned in the context of its increased influence as a greenhouse gas since the pre-industrial era. It is commonly assumed that the level of carbon dioxide in the atmosphere before this time was of 290 ppmv, but more recent indirect data points at a value closer to 260-270 ppmv.