The temperature has gone wildly up and down the past week or so in Rappahannock County – the subject of much local conversation, though par for the course for a Virginia springtime. Meanwhile, another measurement reached a record high a few days ago but went largely unnoticed, much less remarked upon.
The last time such a measurement occurred that was this high, say scientists, happened three million years ago. That was during an epoch called the Pliocene, long before our earliest human ancestors even started using stone tools. The earth’s climate was then far warmer, the world’s ice caps much smaller and the sea level as much as 80 feet higher than today.
The record measurement – of an average daily level above 400 parts per million – is for the heat-trapping gas we know as carbon dioxide (CO2).
For the past one million years, the carbon dioxide level fluctuated in a narrow band of 180 parts per million (during the Ice Ages) and 280 parts per million (during warm periods). And for the entire 8,000 years of human civilization, the carbon dioxide level had remained relatively constant until the Industrial Revolution, when large scale burning of fossil fuels began.
Releasing the carbon stored in those fossil fuels has caused more than a 40 percent increase in the heat-trapping – and climate-altering – gas. The 400 parts per million record means, in the words of one scientist, “we are quickly losing the possibility of keeping the climate below what people thought were possibly tolerable thresholds.”
“It feels like the inevitable march toward disaster,” says another. “It takes a long time to melt ice, but we’re doing it,” says yet another scientist.