Sarah Perkins-Kirkpatrick (‏@sarahinscience) makes a brave attempt to prove that  February heat was caused by CO2

There she is.  Isn't she gorgeous?  She looks fairly young -- which may be why she has stepped in where wiser heads have not

Old campaigners like James Hansen and Michael Mann have claimed the February temperature uptick as a sign of anthropogenic global warming.  They admit that El Nino had something to do with it but just dismiss the El Nino contribution as "minimal" with a wave of the hand.  They don't argue for a particular number, as a real scientist would.

But Sarah has risen to the challenge.  She has attempted to give a figure for the El Nino influence!  And the way she does that is fine in principle.  She takes the rise due to El Nino in 1998 and uses that to reduce the 2016 figure.  So she gives a quarter of one degree as the El Nino contribution -- which still leaves a fair bit of warming available for explanation as caused by a CO2 rise.

Just how your derive the 1998 figure for the influence of El Nino is not totally clearcut.  It depends on what you compare the 1998 figure with.  But I will not cavil about that.  I just want to point out the observed warming COULD NOT have been caused by a CO2 rise.  Why?  Because CO2 did not rise in the relevant period.  Cape Grim shows CO2 levels stuck on 398 ppm for the whole period of late 2015 and early 2016.  Sorry, Sarah!  You should have looked that up.

Now it may not be El Nino only that caused the temperature rise.  There are other possible natural factors that could have had an effect. And Sarah points to one:  The Arctic.  She is enough of a scientist to know that melting sea ice does not raise the water level but she points out that less ice may lead to more heat absorption from the sun.  Fair enough.

But what caused the Arctic melt?  In the absence of a CO2 rise we know it cannot be that.  It was partly El Nino and partly subsurface vulcanism, probably.  A few years back it was  discovered that there was furious underwater volcanic activity in the Arctic, particularly along the Gakkel ridge.  But volcanoes are uneven in their eruptions so they should give rise in random ways to melting in the ice above them.  And that accounts for the uneven pattern of Arctic melting and its lack of synchrony with temperatures elsewhere.  But Warmists act as if the volcanoes cause NO melting.  They need to be that crooked.

And here's some other pesky news 2015 was only the SECOND hottest year on record for Europe.  They must not have got much effect from El Nino -- which is as you expect.  Europe is a long way from the Pacific, where El Nino reigns.  Give up, Sarah!  What you have been taught is WRONG.  You are living off a lie!

Most people know by now that last month was the hottest February since modern records began. It was also the hottest overall month on record, and by the largest margin.

The global average temperature anomaly was 1.35ºC above the 1951–80 average and 1.21ºC above the entire twentieth-century average. For temperatures over land, the deviation almost doubles to a whopping 2.31ºC above the twentieth-century average. Other records broken by February 2016 include the fact that it was the tenth consecutive month in which the global average monthly record was broken and that it completed the hottest three-month period on record (December 2015 to February 2016).

Normally, climate scientists don’t get too anxious over a single month; our blood pressure tends to rise a bit more when record-breaking temperature anomalies are consistently smashed. But February is a special case – not only did it set a new record in an increasingly concerning upwards trend, but the magnitude of the record is terrifying.

So what led to this monster of a month?

First, let’s take a look at the possible influence of the El Niño/Southern Oscillation. The 2015–16 El Niño was one of the earliest and strongest on record, easily comparable to its brother in 1997–98. At the global level, El Niños can cause measurable increases in temperature. We saw this in 1998, in our hottest year on record at the time: thanks to climate change, 1998 would have been a warm year without the El Niño, but the record set would have been smaller.

While the latest El Niño is weakening, its legacy is likely to have had a similar effect on our most recent hottest year on record (2015) and the monster February – increasing the anomaly by just a little bit more than what climate change could achieve on its on. But there is no possible way that an observed El Niño, however strong, could solely explain such a huge monthly temperature deviation. Past El Niños have only intensified global average temperatures by up to 0.25ºC, though the measured influence is usually smaller.

The second factor is the state of the Arctic, where the sea ice extent was more than 7 per cent below the 1981–2010 average, and the ice coverage the smallest since records began in 1979. Over relatively short timescales (monthly-seasonal) a lack of sea ice drives up temperatures. Ocean water is much darker than ice, so radiation from the sun that is normally reflected by the sea ice is absorbed, thus increasing temperatures.

Over longer timescales (years and decades), this sea ice/temperature interaction drives itself – increasing temperatures melt more ice, driving further increases in temperature – through a process known as a positive feedback. Record-low Arctic sea ice during February 2016 and the associated extreme temperatures are consistent with the positive feedback interaction triggered by anthropogenic climate change.

This basic physical interaction drove regional temperatures to well over 11.5ºC warmer than the 1951–80 average. These alarmingly warm conditions were not just confined to the Arctic waters. Because of the influence of sea ice (or the lack of it) on atmospheric circulation, similar temperature extremes were measured well south of the Arctic Circle – over Northern Europe, Russia, Alaska and western Canada.


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