#3 What, me worry? Carbon 101
We’ve all heard endlessly about greenhouse gases — they allow the sun’s energy to reach earth’s surface, but prevent much of it from reflecting back into space. There are several gases that have this effect, but carbon dioxide, or CO2, is the Big Kahuna, because it remains in the atmosphere for so long.
Throughout the 4.5 billion years that our planet has been spinning about the sun, the levels of carbon dioxide in the atmosphere have varied widely. Events such as volcanic activity have tended to increase it, and living organisms have largely driven it down, at least until homo sapiens came along. Shell building organisms in the oceans have sequestered vast quantities (as calcium carbonate or limestone) in seabeds, and photosynthetic plants have done the same on land, in the form of coal, oil, gas, forests and soils.
Scientists have made rough estimates of CO2 levels going back at least 2 billion years, but for the last 800,000 years we have truly accurate data thanks to tiny air bubbles trapped in ancient ice. That period shows peaks and valleys coinciding with ice ages and warmer interglacial periods, and covers the entire time span wherein modern humans evolved.
About one hundred years ago, CO2 levels started to skyrocket. In fact, today’s levels are the highest in over 25 million years, when temperatures were reckoned to be about 4 - 6C degrees higher than in 1900. Since the beginning of the industrial revolution, when people started deriving power from sequestered carbon, global temperatures have risen about 1C degree.
The rub — there is roughly a 50 year lag between atmospheric CO2 levels and the temperatures that result from them. That means that the climate effects of greenhouse gases that we are seeing today are the result of CO2 levels we zoomed past in the 1970s. We’ve seen what a 1C degree rise can do. Are we going to stand around wondering what another 3 - 5 degrees might be like?
THINGS TO DO:
* Think about your carbon “footprint”. Average CO2 emissions per capita in the United States is about 14.24 metric tons. In China it is 7.41 tons. In Kiribati, a nation that will be flooded out of existence in a generation, it is 0.57 tons.
* Watch the movie Anote’s Ark, available on Apple TV and elsewhere.
Thanks for thinking about this,
Doug Hylan, Brooklin, Maine
“It’s not that the world hasn’t had more carbon dioxide, it’s not that the world hasn’t been warmer. The problem is the speed at which things are changing. We are inducing a sixth mass extinction event kind of by accident and we don’t want to be the ‘extinctee.’” Bill Nye