400ppm history lesson for sceptic amateurs

As the daily average CO2 concentration figure exceeds 400 parts per million for the first time in millions of years, it's clear we need to start listening to scientific professionals rather than amateurs driven by phobias and commercial interests.

On Thursday last week the US National Oceanic and Atmospheric Association’s daily average CO2 concentration figure exceeded 400 parts per million at its Hawaiian sampling station. Scientists estimate that the last time CO2 levels were so high was during the Pliocene – a geological era between three to five million years ago, prior to the evolution of humans.

It brought to mind the following reader comment on Climate Spectator:

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