Jeff Condon didn’t seem pleased with my last post about his fake skepticism. He protested that all he had done was “plot some data in a reasonable fashion and make no conclusion.” I think his definition of “single-year ice” isn’t single-year ice and that single-year ice isn’t a good metric for the cryosphere anyway. I also think he selected his definition and presented his plot in order to imply an already-made conclusion. Could it be that he already had an opinion about sea ice, one based on faulty reasoning — the kind that fake skeptics use to fool themselves? Let’s take a look at another of his posts about sea ice.
In “Oops, we hit average” he notes that global sea ice area (all of it) has “hit average.” The first sentence characterizes his interpretation of this event: “Apparently sea ice doesn’t agree with the global warming agenda.” He goes on to say “Despite my belief in CO2 global warming’s effect, I really don’t believe it has had any scientifically discernible impact on sea ice. Nutin!!” He closes with “I’m thinking that after I turn in the useless tax-payer sucking 501C we’ve been discusssing, to no useful effect, I’m going to write a letter to god and turn in the planetary poles for not listening to the government.”
All this because global sea ice actually “hit average.”
Let’s apply some actual skepticism to the notion that “hitting average” indicates global warming has had no “scientifically discernible impact on sea ice. Nutin!!”
Here’s the latest global sea ice area from Cryosphere Today:
Note that it’s back below average again. But it did rise above zero earlier this year. Does that mean there’s been no scientifically discernable impact on sea ice?
One thing we can do is look for a trend with linear regression:
Yes there is one, an average loss of about 40000 km^2 per year, and yes it’s statistically significant (yes corrected for autocorrelation). Contrary to Condon’s belief, there is most certainly a “scientifically discernable impact.”
We can also smooth the data, which indicates that maybe the trend is significantly nonlinear:
This suggests fitting a nonlinear trend, so let’s try a quadratic. That looks like this:
The quadratic term, however, just misses statistical significance at 95% confidence — it only passes at 93% confidence. Nonetheless, that’s evidence (but not proof) that the decline in global sea ice has actually accelerated during the satellite era.
But the real issue at hand is that “hit average” thing. Does that really mean anything? Let’s make some artificial data. We’ll give it a trend of -0.04 (million square kilometers per year), and add noise with standard deviation 0.6 (million square kilometer). Finally, we’ll set the scale so that the average value is zero. Here ’tis:
Notice that it keeps rising above “average” — briefly — despite the strong (and “scientifically discernable”) trend. That’s due to the fact that just because there’s a real trend, that doesn’t mean it stops fluctuating. Yes, folks, it still jiggles up and down. Those jiggles are big enough to take it “above average” sometimes, but the trend is still there.
We can even go back to the actual data and count how often it has risen above the average line. Here’s the fraction of each year for which global sea ice area was above average:
As the years have gone by, the fraction of the time that global sea ice area is above the current “average” level has declined. “Hit zero” events, of which Condon made such a big deal, are getting rarer. Fast.
But that won’t stop Condon and other fake skeptics from making a big deal every time the noise goes against the trend. In fact it’s one of their favorite ploys. And it illustrates, perfectly, just how much they lack any shred of actual scientific skepticism.
The fact is that as sea ice continues to decline (in scientifically discernable fashion), it will still continue to rise above the “average” line — occasionally — until it has declined so much that the noise is no longer big enough to get it back to “average” — ever. I wonder what Jeff Condon will say when that happens?