http://www.geocraft.com/WVFossils/last_400k_yrs.html

Clearly temperature causes changes in the CO2 concentration based on an evaluation of the evidence of the past. The reverse can't be said. It is theoretical that CO2 will cause even the minor warming we have had in the last hundred years. It is also interesting that alarmists ignore all the evidence that CO2 was much more variable and rely strictly on ice core data which has its limitations but when you base your religion on it, it is easy to ignore a few limitations.

Because CO2's effects are logarithmic, the first few molecules matter a lot, but the more you get the less effect they have, this is a fact, at current levels extra CO2's effects are not noticable.

Of course I am taking your statement at face value because I can't really see there being much life on Earth with such low levels of CO2

Ice samples taken from Vostock Antarctica show that co2 levels do not effect temperature, that it's the temperature that effects co2 levels. Co2 lags behind temperatures by some 800 years. There are times when co2 levels are increasing while temperatures are in decline. After about 800 years, the two once again move in the same direction.

Neither the question nor Dr Jello's answer are constrained by logic. Both the question and his answer imply that there are only two variables in the climate system, CO2 and temperature, when deniers have been telling us about other variables for years. I guess in the denier mind you can choose to ignore things if they don't support your argument.

Dr Jello thinks that A implies B means than B cannot imply A, a clear logical fallacy.

It has warmed. And at a considerably faster rate than during the roughly 120,000 years which lasted the period in your example.

During those 120,000 years that CO2 rose from 190ppm to 280ppm temperature rose by some 10oC. That's 1oC every 12,000 years.

The current rate of warming is much, much faster. In just 134 years the globe has warmed .8oC (with two thirds of that warming happening since 1975 or in just 39 years).

Remember, it is not the warming itself which is extraordinary. Many deniers like to claim that it has warmed before but that is not the point: the point is the RATE of the current warming.

It is warming.

It will continue to warm.

Maybe you want to look at how long it took for the world to warm 10C

And keep in mind that CO2 is still rising, and there really isn't a good mechanism to reduce it

So it would appear that over the next few centuries, we can expect the world to warm another 10C.

Check out this graph