Saturday, March 23, 2013

The State of Climate Change - Part 1

Tremendous controversy in the media right now on climate change.  This is a summary of the current state, from a physics point of view.

Climate change used to be called 'Global Warming', but the all the semantics have been shifting over the duration.  We have to separate the good hard science of observation, from the extrapolations.  For observation, it was noted that global temperatures have been rising from the mid 1800's.  This has been a good thing for Canada, since the winters of the early 1800's were almost unliveable, and we don't want to go there again.

Obviously the temperature rise had to be set in context, and this has proven to be difficult and constantly subject to revision.  Most of the current media vitriol is related to this.

Global temperature has always risen and fallen in response to titanic forces.  In fact it is amazing that it always stays in a fairly narrow band conducive to life.  These forces include:  sun output, orbit cycles, carbon dioxide and water vapour and other muck from volcanism, ocean currents, and the jet stream.  From a physics point of view, these energies are orders of magnitude above anything man can do.  Sort of like earthquakes.

We had our super-warming when all the continents came together and the dinosaurs reigned.  Since the continental break-up, we've had numerous ice ages, with very warm interglacials.  Nobody knows how these forces interact, and any attempt to produce a single forcing cycle, such as orbital cycles, has always failed.

Within the last 10,000 years, there have been numerous warming and cooling cycles.  The problem is that nobody was there with a thermometer!  This is exactly the same problem with have with earthquakes, and trying to determine past rates.  Thus, we go to 'surrogates' such as sediments, tree rings, ice cores, etc.  None of these are that good, and have large error bars.

With earthquakes, we then produce a 'sensitivity' time line, which is basically an idea of how many earthquakes we've missed.  You can think of this as the 'resolution' of the past.  Graphs of past temperatures showing a single line do not show evidence of such an analysis, but I'm sure it's there somewhere.

Thus, we have a context problem for temperature, which is subject to ever-increasing shouting.  This problem is even more pronounced when we talk of secondary issues such as the rise rate, or slope of the temperature graph.  There is common talk of 'We have never seen such a fast temperature rise.", when in fact we have no resolution for that in the past.

I believe that the science for plotting world temperatures has been solid, but that the error has been neglected, which is bad physics.  Now, the important political issue has been the extrapolation, or what temperatures will do in the future.  This requires physics, which basically is the science of resolving fundamental forces.

Update:  I'm stopping this, since I just realized climate people on both sides truly believe they are unique.

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