In the news today: new studies of gas bubbles trapped in Antarctic show that current CO2 levels are higher than those for the last 800 000 years — and that the growth in CO2 levels over the last 17 years is so fast that it would normally require over 1000 years of natural variation to produce the same change.
The past 800 000 years includes many ice ages, and interglacial warming periods between the ice ages. The CO2 level fluctuates in step with global average temperature. So we’re looking at a change that in the last 17 years has been larger than that associated with a mere ice age (though luckily other changes are also associated with ice ages). But our CO2 emission rate is still increasing.