The issue that I was referring to is that the earth's climate has been changing throughout its 4.5Ga history, sometimes with far higher maxima and minima than seen recently. To put things into perspective, bear in mind that the last ice age only ended only about 12,000 years ago - an almost invisible division of the geological clock.
From reading all these posts it seems that there is regular confusion made between the phenomena of climate change and temperature variation. Temperature is just one aspect of climate, with large variations evident throughout earth history.
But these questions should be asked:
Can climate and climate change be affected by temperature variation? Yes.
Can climate change and temperature variation be affected by CO2? Yes.
Do greenhouse gases affect global temperatures? Yes.
Is CO2 the most populous greenhouse gas in the atmosphere? No. That's water vapour.
Are CO2 levels the highest ever? No.
Would reforestation lower CO2 levels? Yes, a lot.
Is carbon recycled naturally? Yes but very slowly - millions of years.
Are there any other factors that cause both climate change and temperature variation? Yes, such as as but not limited to changes in: solar absorption, reflectivity, earth orbit and rotation, solar activity, volcanic processes and over a very long timescale, even tectonic effects on the carbon cycle.
Back to topic: Have CO2 levels risen at the fastest rate in recent earth history (late Holocence)? Yes and the rapid rise in the last 200 years is indeed coincident with not only the Industrial Revolution and its resultant emissions but also large rises in the human (and other animal) populations, deforestation and construction.
The last question is critical to this topic and as it is evident that anthropogenic CO2 emissions are responsible for at least part of today's climatic extremes (although I think the Carbon the sink factor is just as important), then they need to be reduced. That said, this world has never had to deal with so many of us making a mess of it. Mother earth will be OK but I'm not sure about us.