As CO2 levels hit a new record global high of 405.66 ppm yesterday, I couldn’t help but think that HG Wells could not have imagined a more perilous mechanism for exploring the world’s past.

For when it comes to testing the range of new climate extremes, the present mass burning of fossil fuels is like stepping into a dark time machine. As all that carbon hits the airs and waters, the climate dial spins backward through hundreds of thousands and millions of years. Speeding us on toward the hothouse extinction eras of Earth’s deep history. Now, not only is it driving us on through extreme weather and temperature events not seen in 100, 1,000, 5,000 or even 10,000 years, it is also propelling us toward climate states that haven’t occurred on Earth for ages and ages.

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Ever since 1990, the world has experienced atmospheric CO2 levels in a range…