Earth is heating up, fast. This year we’re destined to set a new record for hottest year globally … for the third year in a row. Sea level is now high enough that coastal cities are spending hundreds of millions of dollars to fight flooding they get even when there’s no rain or wind or storm … just high tide. Arctic temperatures lately have been crazy hot, not just hot, but crazy hot, while sea ice in the Arctic and the Antarctic is at all-time lows for this time of year. Greenland ice is disappearing before our eyes. Heat waves are on the rise, killing thousands. Persistent drought plagues the U.S. southwest, but in other areas, when rain does fall it’s heavier than it used to be, causing once-in-a-thousand-years flooding to become a lot more common that once in a thousand years. Climate has been changing, not for the better, and it still is.



David Rose, who writes for the U.K. Daily Mail, doesn’t want you to believe it. He wants you to think that the worldwide heating we’ve seen for decades now has somehow, magically, come to an end … that it has shown some kind of “pause.” To give that impression, he had to search far and wide for one set of data from which he can cherry-pick one span of time in which he can focus on one recent event, so he can blame this year’s record-breaking heat on something other than mankind and our greenhouse-gas emissions. Thanks to the many many organizations that publish climate data, there are lots and lots and lots of data sets to choose from … so it’s no surprise he found one.

This one:

It’s global average temperature, not for Earth’s surface where we live, but for the lower layer of the atmosphere … not for the whole world, but for the land areas only … and it’s not all the data, it leaves out the part David Rose doesn’t want you to see. Here’s all the data from this source (RSS, a.k.a. Remote Sensing Systems):

David Rose only shows you the part inside the red box. How stupid does he think you are?

Data like this, in fact almost all data, are a combination of trend — the long-term pattern that actually has some persistence — and fluctuation — the short-term ups and downs that are only temporary. And there are fluctuations. Plenty. They go up and down and down and up, but never really get anywhere.

It’s abundantly obvious, resoundingly unambiguous, completely clear, and pretty simple, that when it comes to climate what matters is the trend, not the fluctuations. For climate deniers, what’s abundantly obvious, resoundingly unambiguous, and completely clear is what they want to avoid. Because it’s so simple, they have to bend over backwards to distract you from it. Like David Rose did.

Here (shown as a red line) is the estimated trend of these data:

Notice how it’s getting hotter? Sure, it still shows ups and downs, all kinds of fluctuations, but the trend, what we expect to persist, is upward. It’s plain to see. How stupid does David Rose think you are?

David Rose wants you to think that maybe, just maybe, the trend has come to a halt, that we’re in the midst of a “pause” in global warming. If we estimate the trend using just the stuff David Rose shows (leaving out what came before because it makes the trend so obvious), the trend estimate is lower, but still upward. But is it really less than before?

Trend estimates by mathematical methods are just that: estimates. That means they’re uncertain. Fortunately, statistics is a powerful enough tool that it enables us to figure out how uncertain they are. That in turn enables us to define a “confidence interval,” a range within which the real trend is most likely to be. We can do that for the overall trend, using all the data, and we can do it for the limited time span that David Rose shows. Then we can compare their confidence intervals:

It turns out, there’s really no statistically reliable evidence that the trend during David Rose’s cherry-picked interval is any different than it was during the whole time span.

David Rose doesn’t just rely on your not being able to do that kind of calculation — few people can — he also relies on your not listening to the experts who can. Because then you’d find out that David Rose’s cherry-picked time span isn’t evidence of anything, except that he can cherry-pick time spans.

How stupid does David Rose think you are?

But his main “evidence” isn’t about the trend, or even the cherry-picked time span he shows (while conveniently removing the data that would provide some context), it’s about the fluctuations. This one:

That extreme high was due, in part, to something called el Niño. It doesn’t create heat out of nothing, but it does increase heat transfer from the oceans to the atmosphere. That makes the atmosphere hotter, at the expense of the oceans, and that’s why an el Niño event raises surface temperature, especially atmospheric temperature, without adding more heat to the earth, just by moving it around. So yes, this year’s record-breaking heat is due, in part, to el Niño.

But not entirely. We’ve had el Niño events before, many times — they’re regular occurences — and they cause a peak in global surface temperature (especially in the atmosphere). But during this particular el Niño, temperature reached a higher peak than any other el Niño. David Rose wants you to think that it’s because this el Niño was stronger than the others, but that’s simply not true. It’s because this el Niño-induced peak was added on top of a hotter starting point, a hotter baseline than the others. That hotter baseline came about because of the warming trend — the one that’s due to global warming.

El Niño is one of the things causing those ever-present fluctuations. But in a changing climate, fluctuation alone doesn’t break records, they’re smashed when fluctuation combines with trend. That’s what has happened this year: the fluctuation of an el Niño was added to the trend of global warming, and that’s why the 2016 record is so extreme. That’s pretty simple, really.

How stupid does David Rose think you are?

Fluctuations go up, fluctuations go down, and every el Niño is followed by a decline. This year is no different. David rose looked around until he found a data set with the biggest post-el Niño decline, then shouted from the mountain-top (from the U.K. Daily Mail, actually) that it just might mean the record heat was only because of el Niño.

How stupid does David Rose think you are?

David Rose cherry-picked the one data set (out of dozens of global temperature data sets) with the biggest post-el Niño decline. He didn’t even show you all of that data set, just cherry-picked the part that didn’t make the warming trend obvious. He turned his focus, not on the trend even for that limited data, but on a pair of recent fluctuations. He suggested that an extreme up being followed by an extreme down was somehow evidence that the recent peak is only due to el Niño, that mankind’s emissions aren’t involved.

Seriously — how stupid does he think you are?

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