Im in the Daily Mail

The Daily Mail (Photo credit: South­East­ern Star ★)

Oppo­nents of the sci­ence behind global cli­mate change have latched on to two recent devel­op­ments in their ongo­ing efforts to claim what’s hap­pen­ing isn’t hap­pen­ing. First is a counter-​​intuitive fact: Antarc­tic sea ice has reached a new his­toric max­i­mum. How can ice in the ocean around Antarc­tica be increas­ing if the earth is grow­ing hot­ter? Sec­ond is a claimed sta­tis­ti­cal lull in the rise of global land tem­per­a­tures, lead­ing Britain’s Daily Mail to con­fi­dently pro­claim, “Global warm­ing stopped 16 years ago, reveals Met Office report qui­etly released… and here is the chart to prove it.”

Are the cli­mate change deniers right? Can we sleep soundly now? Let’s take a closer look.

First, on the mat­ter of the “Met Office report”, one released “qui­etly” (so as appar­ently to not draw atten­tion to the truth behind the global warm­ing hoax). Putting the claims into con­text, the Daily Mail has long been a cham­pion of cli­mate sci­ence oppo­si­tion. That doesn’t make them wrong, but it does seem to make them partisan.

Their claim is that a recent “report” shows “The world stopped get­ting warmer almost 16 years ago,” and this “ ‘plateau’ or ‘pause’ in global warm­ing has now lasted for about the same time as the pre­vi­ous period when tem­per­a­tures rose, 1980 to 1996. Before that, tem­per­a­tures had been sta­ble or declin­ing for about 40 years.” This report “was issued  qui­etly on the inter­net, with­out any media fan­fare, and, until today [Oct 13], it has not been reported.”

There are so many false state­ments and impli­ca­tions there it’s hard to know where to begin. First, there was no “report”. Britain’s Met Office reg­u­larly releases com­pi­la­tions of weather and cli­mate data, and did so in early Octo­ber as it always does. The Met Office itself responded to the Daily Mail arti­cle this way:

Firstly, the Met Office has not issued a report on this issue. We can only assume the arti­cle is refer­ring to the com­ple­tion of work to update the HadCRUT4 global tem­per­a­ture dataset com­piled by our­selves and the Uni­ver­sity of East Anglia’s Cli­mate Research Unit.
We announced that this work was going on in March and it was fin­ished this week. You can see the HadCRUT4 web­site here.

Any impli­ca­tion there was an attempt to coverup or play down an embar­rass­ing “report” is clearly false. But what about the sub­stance of the data? What did the most recent tem­per­a­ture record­ings show?

Recent global tem­per­a­tures, Daily Mail graphic

To the right is the “chart” (actu­ally, it’s a graph) which the Daily Mail claims is “proof” that global warm­ing “stopped” six­teen years ago. Notice a few things here; we’ll come back to all of them. First, it shows monthly read­ings for the period 1997–2012. Sec­ond, there are large peaks in 1997 and 2006, and large val­leys in 1999–2000 and 2007. Third (this is the one the Daily Mail really likes) the aver­age tem­per­a­ture at the begin­ning of the time period is the same as at the end (do you sup­pose this is the rea­son the par­tic­u­lar time inter­val was selected?). Fourth, these tem­per­a­tures are rel­a­tive to some­thing — “tenths of a degree above and below 14°C world average”.

Where did that “14°C world aver­age” tem­per­a­ture come from? It has its ori­gins in the way cli­mate sci­en­tists mea­sure world aver­age tem­per­a­tures, by pick­ing a base­line from which to judge changes. The graphic here claims the tem­per­a­tures graphed are “above and below” the “aver­age”, but do note they are all actu­ally “above” — the bot­tom of the graph is at 0 and the top is at 0.9. The stan­dard used — 14°C — was the aver­age base­line tem­per­a­ture for the period 1940–1980. These dates are impor­tant. Remem­ber the Daily Mail arti­cle claimed that tem­per­a­tures had “risen” from 1980 to 1996 (imply­ing that was the whole basis for claims of “global warm­ing”) and that tem­per­a­tures had been “sta­ble or declin­ing for about 40 years” before that — in other words, from 1940 to 1980.

Global tem­per­a­tures 1880–2011

Here is a graph of global tem­per­a­tures since 1880, show­ing the fea­tures described by the Daily Mail. (It’s click­able, so you can see it full-​​size.) The entire Daily Mail graphic com­prises the tiny plateau in the upper-​​right-​​hand cor­ner of the graph. The steep rise from 1980 to 1996 is the “pre­vi­ous period when tem­per­a­tures rose,” and the rel­a­tively sta­ble era from 1940 to 1980 serves as an arbi­trary base­line used by cli­mate sci­en­tists to track changes in global temperature.

Note that the trend is clearly upward, for more than a cen­tury — with short-​​term ran­dom walks up and down, yes, but there is no mis­tak­ing a very long-​​term, very clear — and rapidly accel­er­at­ing — trend­line. Seen in con­text of the full dataset, the very short plateau of the last few years is noth­ing unusual as part of the com­plete upward move­ment. Com­pare it, for instance, to a sim­i­lar “plateau” around 1990, or another one around 1960.

In fact, nine out of the ten hottest years on record have hap­pened since the year 2000, as part of this “plateau” that the Daily Mail claims is “proof” that the world has stopped warming.

The Daily Mail made no attempt at trend analy­sis, but con­cen­trated instead on short-​​term noise. As if to stress that ran­dom chat­ter, they pre­sented monthly aver­ages, and chose a par­tic­u­larly warm year — 1997 — as the start­ing point, and a rel­a­tively cooler year — 2011 — as the end­point (2011 was “only” the ninth warmest year on record). The peaks and val­leys even within that short time­frame show that any given tem­per­a­ture read­ing will be encoun­tered mul­ti­ple times as the ran­dom noise of tem­per­a­ture read­ings are tal­lied. It is very easy to pick an arbi­trary times­pan with sim­i­lar begin­ning and end­ing tem­per­a­tures, dis­play the chaotic read­ings between those points, and claim that the trend has “stopped”.

Using a cherry-​​picked short span like this is sim­i­lar to using sta­ble tem­per­a­tures in Chicago between May 1 and May 7, and using that to “prove” the weather doesn’t get warmer when com­par­ing Decem­ber to August. And mak­ing a point out of the 1940–1980 base­line is like say­ing that if we com­pare May’s tem­per­a­tures to those from March, we needn’t real­ize it has been warm­ing since December.

Record low Arc­tic sea ice, 2012

All told, the Daily Mail arti­cle proves noth­ing other than the sci­en­tific incom­pe­tence of the peo­ple work­ing at the Daily Mail. But what of the news con­cern­ing Antarc­tic ice? Surely that is of more con­cern to cli­mate sci­en­tists? The Daily Mail arti­cle was no more than fraud­u­lent use of sta­tis­tics. The news from Antarc­tica is a far more com­plex story.

Sum­mer in the North­ern Hemi­sphere, of course, is win­ter in the South­ern. We’ve been hear­ing for years that the sea ice around the North Pole is shrink­ing, set­ting pro­gres­sive records for the least amount of frozen North we’ve ever seen. As the announce­ments are made, deniers like to remind us that Antarc­tica still has plenty of sea ice around it. Of course, the argu­ment hap­pens at the height of South­ern win­ter, and the year’s max­i­mum extent of antipo­dal ice.

This year, the stakes are higher. In the North, this sum­mer marks a record low for Arc­tic ice — 50% below the 1979–2000 aver­age. You can see in the map on the right the record low level of ice. There is open sea in places there has not been open sea since before the last ice age.

In the north, the sit­u­a­tion is fairly sim­ple. The Arc­tic is an area of open sea sur­rounded by land. If the tem­per­a­ture of the air and water rise, the ice melts, and the sur­round­ing land pre­vents water from flow­ing in to mod­ify the tem­per­a­ture in either direc­tion. What hap­pens in the Arc­tic, stays in the Arctic.

Record high Antarc­tic sea ice, 2012

The story in the South is dif­fer­ent. In many ways it is the reverse of the North, and not just because of the reversed sea­sons. The con­ti­nent of Antarc­tica is land, sur­rounded by water. Oceans on all sides cir­cu­late and mix from lat­i­tudes closer to the equa­tor. The sea ice sur­round­ing the con­ti­nent melts almost com­pletely every sum­mer, aside from a few pro­tected places such as the Ross Ice Shelf. When sea ice forms in the win­ter, it isn’t a solid sheet; it’s a col­lec­tion of large and sep­a­rate float­ing chunks. This matters.

This win­ter, Antarc­tica is sur­rounded by a record expanse of sea ice, roughly 5% more than aver­age. (The image to the left is click­able to see it full-​​sized; you have to look close to see the line that shows the dif­fer­ence between the cur­rent max­i­mum and the aver­age max­i­mum.) The dif­fer­ence in the change is thus far less than the change in the north. Still, it is a record. Does this mean the south is cool­ing, while the north is warm­ing? Does it mean the two bal­ance out, and thus the Earth’s tem­per­a­ture is remain­ing fairly constant?

No. In point of fact, the win­ter sea ice around Antarc­tica is at a record high because the Earth is warm­ing, and because of other things humans have done to the planet. There are sev­eral effects involved, since the sit­u­a­tion, as I said, is complex.

First, the ozone layer above the South Pole has been severely impacted by human air pol­lu­tion. The ozone layer acts as a blan­ket to help keep heat in (as well as keep­ing ultra­vi­o­let radi­a­tion out). With the ozone sig­nif­i­cantly depleted at the South Pole, heat is radi­ated into space, and the air tem­per­a­ture over the con­ti­nent tends to go down.

Far­ther from the con­ti­nent, the air and water is warmer. And it is get­ting warmer still, because the Earth is, in fact, heat­ing up. Warm air is less dense than cold air. This sets up strong winds from the south (cooler than nor­mal because of the depleted ozone layer) toward the north (warmer than it was because of global warm­ing) and these strong winds push blocks of sea ice away from the con­ti­nent. At the same time, warmer air can hold more mois­ture than cooler air. There are more fre­quent storms now than there used to be above the waters sur­round­ing Antarc­tica, and they are more severe, drop­ping more snow into the frigid water, which freezes into more sea ice.

All told, this means the mod­er­ate expan­sion of sea ice we’re see­ing around Antarc­tica is caused by human-​​influenced global cli­mate change, rather than being evi­dence against global warm­ing. It’s hap­pen­ing because the Earth is get­ting warmer, and because of other things we’re doing (such as deplet­ing ozone).

The ver­dict here? Both of these newly-​​popular memes from cli­mate change deniers mean some­thing other than what the denial indus­try wants them to mean. Both are evi­dence of the con­tin­u­ing, and wors­en­ing, of global warm­ing. One has to won­der whether the earth’s cli­mate would cool, at least a lit­tle, if only the sci­ence deniers didn’t pro­duce so much hot air.

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