After a busy few days dealing with a Houdini-like chicken (one of our two Light Sussex) and one of my ever-eager whippets (“It moved! Catch!!”) that’s involved re-fencing the chicken run, re-siting the big dog-run and training the dogs that if I see them look at a chicken I will shout at them (nothing can guarantee their behaviour when they think I’m not looking, but at least now they glance round to see if I’m watching before pouncing at a stray hen!) I’ve had time to catch up on the news slightly. Oh, and the chicken is fine despite her adventures with the dog.
This week, the Scripps Institute for Oceanography have released a piece of news that I find slightly depressing. On March 12th, 2014, the Keeling Curve topped 400ppm of carbon dioxide for the first time this year.
The Keeling Curve is a record of measurements of carbon dioxide in the atmosphere. Ever since Charles David Keeling began to measure atmospheric carbon dioxide from the top of Mauna Loa in 1958, the concentration of this important greenhouse gas has been recorded every day. In 1958, the concentration was 313 parts per million (ppm); it is slightly higher at night when plants are respiring oxygen (just as we animals do) and lower in the day when photosynthesis is active, turning carbon dioxide from the air into sugars in plant leaves. It increases in the spring, reaching a maximum around May, and decreases through the rest of the summer and into winter, showing how plants use carbon dioxide from the air in their annual growth cycles.
Ever since 1958, the average concentration has been rising, year by year. Last May saw carbon dioxide concentrations top 400ppm for the first time in recorded history. This year, that figure has been reached two months earlier in the year, and we should expect it to continue to rise through to May.
What does this mean?
Apart from the obvious but basically meaningless sound-bites (every breath you take now contains more CO2 than ever before!!), in immediate everyday terms, not a lot. We’re not physically capable of determining what’s in the air we breathe without complex testing gear, so the air doesn’t smell different, or feel different. As long as we still have upwards of 17% oxygen in the air we’re not about to pass out from lack of oxygen (normal air has about 20% oxygen) so really carbon dioxide concentrations aren’t going to impact on our day-to-day living.
There’s an old parable about boiling a frog: if you put a frog in a pan of boiling water, it’ll jump out. If you put a frog in a pan of cold water and bring it to the boil, the frog stays in the pan, not noticing the change in temperature until too late.
Let’s face it: most humans are, in this sense, frogs. We’ve been in the water (not personally, but you get the idea!) since before the Industrial Revolution began, when carbon dioxide concentrations are estimated to have been around 280ppm (from ice-core data). We’re not really geared to think in long-enough time-scales for planetary engineering, perhaps. The changes are gradual and take years, and suddenly the pan is bubbling and we’re still in the water, wondering what’s going on.
On a more cheerful note, today is the Vernal Equinox, the official day when spring has, definitely, sprung. That doesn’t mean we may not get wintery weather in the next few weeks, of course – last year we were snowed in for a few days at the end of March – but it does mean that the evenings are lighter and the dawn chorus is kicking off earlier. Today, the length of the day and the length of the night are equal (hence “equi nox” – equal night) and I feel as if the winter’s behind us and the year is opening up ahead.