Friday, 22 August 2014

"Global warming slowdown could last another decade"

From the BBC:

The hiatus in the rise in global temperatures could last for another 10 years, according to new research.

Scientists have struggled to explain the so-called pause that began in 1999, despite ever increasing levels of CO2 in the atmosphere.

The latest theory says that a naturally occurring 30-year cycle in the Atlantic Ocean is behind the slowdown.

The researchers says this slow-moving current could continue to divert heat into the deep seas for another decade.

However, they caution that global temperatures are likely to increase rapidly when the cycle flips to a warmer phase.

I love the concept of the "so-called pause". Either it was or it wasn't.


Bayard said...

"Scientists have struggled to explain the so-called pause that began in 1999, despite ever increasing levels of CO2 in the atmosphere."

Apart from the obvious explanation that the two are in no way connected, of course.

paulc156 said...

'so called' pause because average surface temperatures have apparently paused but sea temperatures are rising, particularly at deeper levels. When those same currents currently limiting surface temperatures change as they will inevitably do at some point [it's a cycle innit] we should then see quite marked increases in surface temperatures. If we don't 'skeptics', [Nigel Lawson and half a dozen others...]may have a point. Don't hold your breath.

A K Haart said...

A simple explanation is that rising ocean temperatures caused the increase in atmospheric CO2 rather than the other way round.

The solubility of CO2 in water being inversely related to temperature.

Mark Wadsworth said...

B, nah, too obvious.

PC, OK, so the ten year "so called pause" turns into a twenty year "co called pause" turns into thirty etc.

At what stage does it stop being a "so called pause"?

AKH, very true, but does anybody know why the oceans warmed in the first place?

Bayard said...

"does anybody know why the oceans warmed in the first place?"

Even the most ardent warmmongers don't deny that the Earth has been warmer than this before, it's just a case of whether it's a few hundred years, a few million years or a few hundred million years. So that's what the Earth does, gets warmer, then cooler. The evidence that warming leads to elevated CO2 levels is pretty simple, as stated by AKH above. The evidence for the reverse is extremely complicated. I invoke Occam's Razor.

paulc156 said...

AKH cites a rise in ocean temperatures as an explanation for rising atmospheric CO2 which begs the question as to what happens 'after' a 'warming gas' goes into the atmosphere? Could it then lead to a rise in air temperatures after some time lag? 'If' there were no countervailing trends this would absolutely lead to an increase in temperature. So stating the warming oceans caused some increase in CO2 in no way mitigates the claim that rising CO2 production is also causing rising ocean temperatures. In other words AKH's inference [which I am assuming is the case here]that warming oceans are responsible for rising Co2 rather than any rising Co2 due to anthropogenic causes is a non sequitur.

MW. The pause is over when it's over, or it isn't a pause if we head straight into the ice age. To be revealed. I called it 'so called'. That it's a pause is self evident. The temperature has stopped rising since circa 2000. Since author of the cited study talks of a 70 year cycle he is anticipating a reversal in the cycle as likely to occur in ten years or less. He cites falling salinity since 2006 as evidence of a pending reversal in this cycle. The ocean current cycle will reverse, not quite as certain as night follows day but... when it reverses we get to test the theory. The data on these ocean cycles is quite limited though so maybe it could feasibly be longer than 10 years. I hear Iceland's volcanoes are getting active again though so maybe there will be other limiting factors coming to the rescue.

Mark Wadsworth said...

B, exactly.

PC: "maybe there will be other limiting factors coming to the rescue."

To the rescue of what? Volcanoes do go up every now and then, that knocks temperatures back a bit. Then it warms again.

If we follow your logic to the extreme and accepting that the Earth has had much warmer periods before with resulting much higher CO2, can you explain why this reversed itself?

paulc156 said...

MW. 'To the rescue' of those who are adamant that anthropogenic warming is a non issue or trivial.

'My logic' is what exactly? Only you don't explain. Earth has had higher CO2 in the past. It was also a lot,lot warmer. There are other factors than man made CO2, did anyone say there weren't?
For example, if we wait long enough the Milankovitch cycle could provide some cooling effects as it is thought to have done periodically for the last million years or so at any rate.[glacials roughly every 100K years with 10-15K inter-glacials. Though these are thought to have dominated only in the recent million year or so.

If we are even more patient there could be further significant changes to the Earth's tectonic plates such that we might find ourselves with a different continental alignment. This has massively affected climates in the past. Gondwana land's break-up led to significant cooling especially once Antarctica separated from South America/Africa etc.

Asteroid hits [eg;65mya] have likewise had major climatic effects. Massive lava outflows [Deccan Traps 250 mya-biggest mass extinction event??] both brought epoch ending changes to Earth's climate. Obviously, these phenomena all directly and indirectly impact on atmospheric CO2.

View from the Solent said...

The paper by Chen and Tung is a description of the 60ish year Atlantic Multidecadal Oscillation. The clue is in 'Oscillation'; it's a cycle.
It was at a low point around 1975 and went on an upward trend to ~2000. It's been flat since, corresponding to flat Northern Hemisphere temperatures in the satellite data. In a few years time it will start its downward phase; it's gonna get cold.

Kj said...

A funny perspective on climate from this article:
More than a dozen theories have been put forward on the cause of this pause in temperature growth that occurred while emissions of carbon dioxide were at record highs.

These ideas include the impact of pollution such as soot particles that have reflected back some of the Sun's heat into space.

Increased volcanic activity since 2000 has also been blamed, as have variations in solar activity.

The New frontier in climate science, figuring out why temperatures aren't increasing when they should, because we said so it should.

paulc156 said...

VFTS. No an end to the cycle you cite would infer 'it's going to get warmer' not 'colder'. 1945 and 1975 was the last cooling effect part of the cycle and then 24 odd years since then came a warming period as the heat transferred energy to the surface. Since 2000 the heat went deeper along with increased levels of salinity but since 2006 that process has halted and has reversed. That is salinity has reversed but remains above its long term average. If it continues to fall then the implication is that heat is rising to the surface as sea ice melts and reduces the salinity.

Kj you just invented a straw man then beat him down. Actually no climate scientist or scientist involved in studying aspects of climate has ever [to my knowledge] stated that the effects of increasing CO2 would lead to a linear increase in surface temperatures without any temporary changes in temperature trends. Quite the reverse.They made explicit that there would likely be significant periods where temperatures stabilise or reverse to some extent.

Mark Wadsworth said...

VFTS, Kj, thanks for back up.

PC, I don't get it. Until a few years ago, I "believed" in global warming and it being caused by CO2.

Then I thought I'd better gen up on this a bit and none of the arguments or explanations stack up, not in the slightest.

If all the C02 in the atmosphere sank to ground level, it would be a layer about six metres thick. You don't seriously think that this is going to make any difference to anything?

paulc156 said...

MW. I'm not wedded to the certainty of the anthropogenic argument, just that it's where the evidence clearly points and until proven otherwise.
The argument from incredulity [CO2 only "a layer about six metres thick"]is hardly convincing. Ozone is only a few millimetres thick and without it we'd be in deep shit. Almost like saying a teeny bit of polonium can't be all that bad, it's just so... teeny.

After all even the die hards accept that Co2 is a warming gas [though I'm not sure about those on here tbh]. We know that under normal circumstances there is a carbon cycle which keeps things in some sort of balance but are faced with ever increasing amounts of carbon having to be absorbed in short time [dozens of years really] from sources that under normal circumstances-pre industrial- would not be available. In the past such unusual events correlate with unusual temperature movements both up and down. How many metres/kms thick would it need to be to persuade you. What would be your justification for suggested thickness?

adamcollyer said...

Yes, this was a seriously hilarious article, wasn't it?

"What are we going to do about the fact that the warming has stopped, Fred?"

"I know, Jim, let's just say we expect the pause to last ten years. Should take us nicely into retirement anyway, and who knows, the warming might start up again by then!"

Mark Wadsworth said...

AC, yes, I think that must be how it works.

Bayard said...

"After all even the die hards accept that Co2 is a warming gas"

I doubt it. There is a postulated mechanism by which additional CO2 can cause the Earth to become warmer and there is strong evidence that a rise in temperature is accompanied, in general, by a rise in CO2 levels, and vice versa, but there is no evidence to show which causes which and the only evidence that backs up the postulated mechanism is the very effect that the mechanism was postulated to explain.

This wouldn't be a problem if the so-called "climate science" really was a science. In science, a theory is proposed and all scientists do their best continually to disprove the theory. All questioning and evidence to the contrary is welcomed as part of the "scientific method". The main thrust is to find out what is going on. That doesn't sound like what is is going on here, does it? How about if we call it something else, like a belief, or a religion, even? Now, in a religion, dogma is propagated and those who question the dogma, the accepted beliefs, are attacked and rejected as heretics, blind to the truth. The main thrust is to get other people to take on the accepted beliefs. That sounds a bit closer to the mark.