A WUWT contributor who calls himself “justthefacts” has written a post which attempts to tout the so-called “pause” in global warming. It’s pretty well summed up by the title of this post.
I’ve come to expect that from all corners of the denialosphere. What surprised me, however, was the conclusions based on data for snow and ice. I’ve mentioned before that it’s no use even talking to those who deny that what’s happening to the cryosphere is powerful evidence of global warming. They’re so deep in denial they can’t be reasoned with.
Here, for instance, is his summary of the message from sea ice:
There appears to have been a negative trend in Northern Hemisphere Sea Ice Area and Extent, especially around Minimum and a positive trend in Southern Hemisphere Sea Ice Area and Extent, thus the resultant Global Sea Ice Area trend appears to be slightly negative. However, in recent years does appear to be a pause as a result of increases in Southern Hemisphere Sea Ice Area and Extent, balancing out decreases in Northern Hemisphere Sea Ice Area and Extent.
No, southern increase doesn’t balance out northern decrease, not even “in recent years.” I hear this kind of thing all the time, but it’s just not true. We can clarify the trend by looking at annual average sea ice area anomaly:
“Pause”? There’s no “pause.” The 5 lowest values on record all happened in the last 7 years. The lowest of all was 2011. And the trend is decidedly downward. Evidence of a “pause” is nonexistent.
So how did he reach such a wrong conclusion? There are many contributing factors. First, he looked at a graph in which anomaly values are squeezed into a very narrow plot range, which makes it easy to think you’ve seen a pause. Second, there are seasonal differences in global ice trends which make graphs less amenable to visual interpretation. Third, he did no analysis at all. None.
Fourth, and most relevant, it’s what he wanted to see.
Speaking of seasonal differences, here’s the global sea ice area during the northern hemisphere autumn season (Sept-Oct-Nov):
“What a pause!” Or should I say, “What? A pause?”
When it comes to northern hemisphere snow cover, not only does he draw the wrong conclusion, he leaves out the most important part of the data. Here’s his summary:
While none of the Snow plots offers a global perspective, when looking at the Northern Hemisphere, there appears to have been a slight increase in Snowcover and Winter Snow Extent, a decrease in Spring Snow Extent and no change in Fall Snow Extent over the historical record.
To hear those conclusions, you’d think that changes in snow cover are no big deal, let alone any evidence of a warming climate.
Here’s snow cover during winter, plotted the way he does:
The graph makes it harder, rather than easier, to see possible trends. Here’s a better version:
There looks like an upward winter trend, estimated at +11,000 km^2/yr, but looks can be deceiving. The trend is not statistically significant. The estimated total change due to trend from start to finish is a gain of 0.51 million km^2, but again that’s not significant.
Now let’s look at snow cover during spring:
Spring snow looks to be in decline at a rate of -67,000 km^2/yr, and this trend is significant. The estimated total change due to trend from start to finish is a loss of 3.02 million km^2.
As for autumn:
The estimated autumn trend is a mere +3,700 km^2/yr, which is nowhere near significant. The estimated total change due to trend from start to finish is a gain of merely 0.17 million km^2, again nowhere near significant.
To summarize, of the three seasons he shows only one exhibits a statistically significant trend. And for that one, the trend is a decrease in snow cover. Even if we take the estimated trends (significant or not) of all three seasons and sum them, with winter at +11,000/yr and autumn +3,700/yr while spring is -67,000/yr, the total comes to decrease at a rate of -52,000 km^2/yr. His characterization is misguided and misleading, at best.
But the saddest part is that he’s left out the most important season. Here’s snow cover during summer:
The estimated summer trend is -88,000 km^2/yr, which is overwhelmingly statistically significant. The estimated total change due to trend from start to finish is loss of a whopping 3.94 million km^2.
Summer snow cover is extra important because that’s when we get the most sunlight, so the reduced albedo (there’s less snow to reflect sunlight back to space) has its greatest effect.
And by the way, evidence of a “pause” is nonexistent.
His treatment of snow cover is just another case of looking at graphs which make trends harder to see, doing no analysis at all, and more to the point: seeing what he wants to see. Except for the added twist of leaving out the most important data, which also most strongly contradicts his wrong conclusion.
I’ll bet that WUWT contributor “justthefacts” actually believes he stuck to “just the facts.” He didn’t. He also drew conclusions. Unfortunately for him, and for us all, his conclusions are wrong. In my opinion, the root cause is that when he looks at the facts, he sees what he wants to see.
Perhaps most telling is that, in spite of having concluded that sea ice loss has “paused” (which it hasn’t) and snow loss is no big deal (although it is), he still felt the need to dismiss the importance of what we’ve seen happen to snow and ice:
Based on the limited Global Ice and Snow measurements available, and noting the questionable value of Sea Ice Area and Extent as a proxy for temperature, not much inference can currently be drawn from Earth’s Ice and Snow measurements. However, there does appear to be a pause in Global Sea Ice Area.
Not much inference? The changes to snow cover and sea ice are so dramatic, that if you don’t infer there are dramatic changes to the climate happening right now, then you’re in denial. Just as one can see what one wants to see, one can also not see what one doesn’t want to see.
Perhaps he’ll read this post and realize that he didn’t just stick to the facts about ice and snow, that he also drew conclusions, and that he was just plain wrong. Perhaps he’ll admit that what’s happening to ice and snow are powerful evidence of global warming as well as powerful evidence against a “pause” in global warming. Perhaps he’ll even re-evaluate his entire approach to the entire issue.
What are the odds?