400 ppm and counting

The first full day of 400+ ppm CO2 as recorded at Mauna Loa in Hawaii last week produced an outpouring of sentiment and grief from many, but the news has seemingly passed. Unfortunately, the arrival of such a day had become inevitable. Since the early days of the Keeling Curve at 315 ppm when it became clearly apparent that anthropogenic CO2 emissions were accumulating in the atmosphere, we have counting up the ppm to this day.

Despite an early clear warning to the Johnson Administration at 321 ppm, it wasn’t long before there was a brief worry about global cooling. Then, with atmospheric chemistry growing as a discipline (probably on the back of concerns about a cold war nuclear winter), we were distracted at 332 ppm by the first major anthropogenic global concern, the hole in the ozone layer. But with a treaty negotiated and ratification underway by 349 ppm (only 17 ppm to sort that one out), it didn’t take long for the science community to remember that another big issue was lurking in the shadows.

At 352 ppm and nearly 40 ppm on from the start of the Keeling Curve, James Hansen stated to a US Congressional Committee that;

  • The earth is warmer in 1988 than at any time in the history of instrumental measurements.
  • Global warming is now large enough that we can scribe with a high degree of confidence a cause and effect relationship to the greenhouse affect.
  • Computer simulations indicate that the greenhouse effect is already large enough to begin to effect the probability of extreme events such as summer heat waves.

But it was another 13 ppm before the Kyoto Protocol was adopted by parties to the UNFCCC and 14 ppm more before it was finally ratified. 21 ppm later and it is a shadow of its former self, but at least with the legacy of some beginnings of a global carbon market. However, it is trading close to zero!! In the interim there was a valiant attempt at a new global deal, but even that was 12 ppm ago.

400 ppm and climbing


Our goal to be avoided, 450 ppm, is now feeling a bit close for comfort, given we are already at 400 ppm and 300 ppm was only passed under the previous British monarch.

Not to worry, it should only be another 15 ppm before a new global deal comes into force, although after more than 3ppm of discussion, the negotiations don’t really seem to have started. So we wait again, hopeful that someone has got a plan.

But a lot can happen in 50 ppm if we try hard and we really want something!! After all, the first world wide web page was posted only 43 ppm ago!