Three Climate Change Numbers To Think About

As long as I’m posting on climate change, let me note three numbers that recently surfaced in that regard:

1. 1.       400 (ppm)
2. 2.       98.4 (%)
3. 3.       Minus 4.2 (%)

Each of these numbers moves the “center of probability” of how climate change is proceeding significantly – but each is really a confirmation of what we should have known already.

Number 1:  400 ppm

This one is perhaps the most widely known – it’s the time a couple of weeks ago when the Mauna Loa record of carbon in the atmosphere reached 400 ppm for the first time since ML started recording in 1950, and almost certainly for the first time in the last 3 million years – when carbon content in the atmosphere was headed in the opposite direction, i.e., down.

What is notable about this event is that had we been doing even a slightly improved job of dealing with carbon emissions, that event would have occurred in 2014 or even in 2015.  Because we did things like shift economic activity to places like China with lagging mitigation strategies, slight decreases in US and somewhat more substantial decreases in European emissions translated into much larger jumps in the last two years in overall emissions.  And so, what this number really tells us is that with the possible exception of Europe, “business as usual” translates into overall acceleration of carbon emissions and thus of climate change. 

Number 2:  98.4%

For years, the one survey on the subject said that 97% of published climate scientists find that human-caused climate change is real – which any good climate scientist should be able to conclude for themselves, without the need for “safety in numbers.”  That, in turn, raised the question:  what about the remaining 3%? 

Well, a follow-up survey is providing the answer to that.  Some of that 3% has been persuaded (which raises the question of why they needed persuading in the first place).  While the most widely quoted figure from the follow-on study says 97.1% now conclude human-caused climate change is what it’s all about, that represents an average over the years; in fact, 98.4% of published climate scientists now see climate change as real, significant, and effectively human-caused.  The 3% are going away.

I suppose this is good news, since some people seem to need convincing that reputable scientists do indeed see matters this way.  But to me, rather, it is simply some of that 3% finally acting like scientists; in which case the next step is for them to join the chorus saying this is serious. And as any shred of support for climate denial continues to shrink, politicians may find themselves more uncomfortable in their belief that issues are balls to play with.

Number 3:  -4.2 %

The sad fact about US emissions measurements is that (probably due to funding) incomplete measurements for a year that increasingly seem to understate them come out immediately, while the best estimates come out 1 ½ years later (in the case of 2011, in mid-2013).  And now we know that 2011, instead of representing a 7% drop from the 2007 booming-economy high, is actually a 4.2% drop.  Much of that, in turn, comes from a real drop in the economy – our actual use of carbon per unit of energy (i.e., a turn away from oil and gas) is only 3.2% down.

Again, this should have been understood – certainly, Joe Romm among others suggested this was going on.  But we may anticipate that 2013, with its housing rebound, is going to wind up as close to an increase in carbon emissions in the US.  And that means that there is no comfort in these US numbers, and no significant trend downwards as the economy recovers slightly.  We are still squarely in the middle of “business as usual”.  The urgency of doing something meaningful continues to increase.  The number of numbers that people can use to justify doing nothing continues to decrease.

Who knows what it will take to spur effective action?  Just know that excuses continue to get shabbier – even as the consequences of inaction that are already locked in get more dire.