When it comes to climate science reporting, the Mail on Sunday and Telegraph are only reliable in the sense that you can rely on them to usually get the science wrong. This weekend's Arctic sea ice articles from David Rose of the Mail and Hayley Dixon at the Telegraph unfortunately fit that pattern.
Both articles claimed that Arctic sea ice extent grew 60 percent in August 2013 as compared to August 2012. While this factoid may be technically true (though the 60 percent figure appears to be an exaggeration), it's also largely irrelevant. For one thing, the annual Arctic sea ice minimum occurs in September – we're not there yet. And while this year's minimum extent will certainly be higher than last year's, that's not the least bit surprising. As University of Reading climate scientist Ed Hawkins noted last year,
"Around 80% of the ~100 scientists at the Bjerknes [Arctic climate science] conference thought that there would be MORE Arctic sea-ice in 2013, compared to 2012."
The reason so many climate scientists predicted more ice this year than last is quite simple. There's a principle in statistics known as "regression toward the mean," which is the phenomenon that if an extreme value of a variable is observed, the next measurement will generally be less extreme. In other words, we should not often expect to observe records in consecutive years. 2012 shattered the previous record low sea ice extent; hence 'regression towards the mean' told us that 2013 would likely have a higher minimum extent.
The amount of Arctic sea ice left at the end of the annual melt season is mainly determined by two factors – natural variability (weather patterns and ocean cycles), and human-caused global warming. The Arctic has lost 75 percent of its summer sea ice volume over the past three decades primarily due to human-caused global warming, but in any given year the weather can act to either preserve more or melt more sea ice. Last year the weather helped melt more ice, while this year the weather helped preserve more ice.
Last year I created an animated graphic called the 'Arctic Escalator' that predicted the behavior we're now seeing from the Mail on Sunday and Telegraph. Every year when the weather acts to preserve more ice than the previous year, we can rely on climate contrarians to claim that Arctic sea ice is "rebounding" or "recovering" and there's nothing to worry about. Given the likelihood that 2013 would not break the 2012 record, I anticipated that climate contrarians would claim this year as yet another "recovery" year, exactly as the Mail on Sunday and Telegraph have done.
Arctic sea ice extent data, 1980–2012. Data from NSIDC.
In short, this year's higher sea ice extent is merely due to the fact that last year's minimum extent was record-shattering, and the weather was not as optimal for sea ice loss this summer. However, the long-term trend is one of rapid Arctic sea ice decline, and research has shown this is mostly due to human-caused global warming.
Both Rose and Dixon referenced a 2007 BBC article quoting Professor Wieslaw Maslowski saying that the Arctic could be ice free in the summer of 2013. In a 2011 BBC article, he predicted ice-free Arctic seas by 2016 "plus or minus three years." Other climate scientists believe this prediction is too pessimistic, and expect the first ice-free Arctic summers by 2040.
It's certainly difficult to predict exactly when an ice-free Arctic summer will occur. While climate research has shown that the Arctic sea ice decline is mostly human-caused, there may also be a natural component involved. The remaining sea ice may abruptly vanish, or it may hold on for a few decades longer. What we do know is that given its rapid decline, an ice-free Arctic appears to be not a question of if, but when.
Both articles also claimed that "some scientists" are predicting that we're headed into a period of global cooling. Both named just one scientist making this claim – Professor Tsonis of the University of Wisconsin, whose research shows that slowed global surface warming is only temporary. In fact, Tsonis' co-author Kyle Swanson wrote,
"What do our results have to do with Global Warming, i.e., the century-scale response to greenhouse gas emissions? VERY LITTLE, contrary to claims that others have made on our behalf."
Both articles also wrongly claimed that global warming has "paused" since 1997. In reality, global surface temperatures have warmed over the past 15 years, albeit more slowly than during the previous 15 years. It is possible to cherry pick a shorter time frame over which global surface temperatures haven't warmed, as I illustrated in my other animated 'Escalator' graphic.
Average of NASA GISS, NOAA NCDC, and HadCRUT4 monthly global surface temperature anomalies from January 1970 through November 2012 (green) with linear trends applied to the timeframes Jan '70 - Oct '77, Apr '77 - Dec '86, Sep '87 - Nov '96, Jun '97 - Dec '02, and Nov '02 - Nov '12.
However, the opposite is true of the overall warming of the planet – Earth has accumulated more heat over the past 15 years than during the prior 15 years.
Global heat accumulation data (ocean heating in blue; land, atmosphere, and ice heating in red) from Nuccitelli et al. (2012).
Recent research strongly suggests that the main difference between these two periods comes down to ocean heat absorption. Over the past decade, heat has been transferred more efficiently to the deep oceans, offsetting much of the human-caused warming at the surface. During the previous few decades, the opposite was true, with heat being transferred less efficiently into the oceans, causing more rapid warming at the surface. This is due to ocean cycles, but cycles are cyclical – meaning it's only a matter of time before another warm cycle occurs, causing accelerating surface warming (as Tsonis' research shows).
It would be foolhardy for anyone to predict future global cooling, and those few who are so foolish are unwilling to put their money where their mouth is, as my colleague John Abraham found out when challenging one to a bet, only to find the other party unwilling to stand behind it.
Both articles also claimed the Intergovernmental Panel on Climate Change (IPCC), whose Fifth Assessment Report is due out in a few weeks, has been forced "to hold a crisis meeting." This claim made both articles even though Ed Hawkins noted,
"I told David Rose on the phone and by email on Thursday about the IPCC process and lack of 'crisis' meeting."
Unfortunately that didn't stop Rose from inventing this meeting, or Dixon from repeating Rose's fictional reporting in the Telegraph.
Finally, both articles quoted climate scientist Judith Curry claiming that the anticipated IPCC statement of 95 percent confidence that humans are the main cause of the current global warming is unjustified. However, Curry has no expertise in global warming attribution, and has a reputation for exaggerating climate uncertainties. In reality, the confident IPCC statement is based on recent global warming attribution research. More on this once the IPCC report is actually published – any current commentaries on the draft report are premature.
Posted by dana1981 on Friday, 13 September, 2013
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