January 12, 2016

Can a few degrees of global temperature change make a big difference?

It is rare to get fact-based comments from Leftists on any of my blogs.  As other conservative bloggers will confirm, enraged and irrational abuse is what one normally gets.  Which tells you a lot about the Green/Left.  Their rage and hate make the horrors of Soviet Russia and Maoist China understandable.

So I was surprised and interested to find that, although he was abusive, one commenter did actually make an apparently rational argument. He said:  "The average global temp of the last ice age was only a few degrees cooler than the 20th century".  And from that he argued that a few degrees of change is all that is needed for big effects in general.  So a few degrees of warming could also  have a big effect.  As we know, Warmists have quite arbitrarily set a temperature rise of 2 degrees Celsius as the knell of doom so are they right?  Could even that small change have a big effect?

But does that argument hold up?  If a few degrees of cooling made a big difference, would a few degrees of warming also make a big difference?  I think we can all see instinctively that "It ain't necessarily so" but let me flesh that perception out.

The earth as a whole is actually a rather cold place relative to the freezing point of water (zero degrees Celsius). The average global temperature at present is approximately 14 degrees Celsius.  And the average global temperature in the last ice age was around 9 degrees Celsius.  So the difference is only 5 degrees -- which does indeed sound alarming.

But any average implies a range above and below it so an average of 14 degrees will mean that there are a lot of places where the number is a lot lower than that.  An average of 14 degrees tells us that there will be a lot of places on earth where the temperature is a lot cooler than that. For circumpolar regions, the temperature will be getting close to zero degrees.

So that makes it very clear why we had an ice age.  Lots of the globe was already pretty cold so a drop of 5 degrees pulled a great part of it below the threshold for ice formation (zero degrees Celsius).

But there is no similar situation for warming.  A couple of degrees of warming is unlikely to cause anything to cross any threshold. It might melt a bit of sea ice but melting floating ice leaves the water level unaffected -- As Archimedes demonstrated about 3,000 year ago.

So yes.  A few degrees can make a big difference but only if you are near some threshold -- and it has not been shown that we are.

FOOTNOTE:  My academic background is in the social sciences.  I am no paleoclimatologist.  So when I first saw the argument by the Warmist, I was nonplussed.  I could see that the argument was invalid but I could not put my finger on why.  But my research background kicked in immediately and I said to myself: "What are the numbers?"  And when I looked up the numbers, I had the answer to the puzzle.  In science, the numbers make all the difference.

And the numbers make a lot of Warmism look absurd.  The annual announcements that the year just past was the "hottest", "third hottest" etc. sound important until you realize that the differences being talked about are in hundredths of one degree only. We actually live in an era of exceptional temperature stability.  It takes the perversity of the Left to call it an era of dangerous warming

Technical note:  I have given 9 degrees as the temperature of the last ice age but that is very much an approximation. It is however a fairly conventional approximation and serves well for the purposes of illustration. There are lower figures, depending on how you balance out the different times and places in the era concerned.  And the whole concept of an average temperature for the earth is a pretty hairy one anyway. -- JR.






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