Year 3, Month 6, Day 11: We Are The Great Four Hundred

The Columbus (IA) Republic, on hitting 400:

For more than 60 years, readings have been in the 300s, except in urban areas, where levels are skewed. The burning of fossil fuels, such as coal for electricity and oil for gasoline, has caused the overwhelming bulk of the man-made increase in carbon in the air, scientists say.

It’s been at least 800,000 years — probably more — since Earth saw carbon dioxide levels in the 400s, Butler and other climate scientists said.

Until now.

Readings are coming in at 400 and higher all over the Arctic. They’ve been recorded in Alaska, Greenland, Norway, Iceland and even Mongolia. But levels change with the seasons and will drop a bit in the summer, when plants suck up carbon dioxide, NOAA scientists said.

So the yearly average for those northern stations likely will be lower and so will the global number.

Globally, the average carbon dioxide level is about 395 parts per million but will pass the 400 mark within a few years, scientists said.

The Arctic is the leading indicator in global warming, both in carbon dioxide in the air and effects, said Pieter Tans, a senior NOAA scientist.

“This is the first time the entire Arctic is that high,” he said.

A rehash of yesterday’s letter. Sent June 1:

I vividly remember the excitement we experienced as kids when our station wagon’s odometer turned over; on the day we passed 100,000 miles, Dad decelerated a bit and my brother and I called off the tenths of a mile until all the zeroes lined up on the dashboard and the family broke out in cheers. We did a lot of driving in those days — unwittingly, it turns out, making our contribution to a far more ominous numerical landmark.

400 parts per million of atmospheric CO2 is nothing to celebrate. We long ago passed the critical level of 350 ppm, the concentration climatologists consider the maximum level consistent with the continued survival of our civilization, and even if we stopped burning fossil fuels completely, things would still keep getting hotter for decades. The next few centuries are going to be a rough ride for life on Earth. Why are the climate-change denialists in media and politics working hard to keep us from buckling up our seat belts?

Warren Senders