Tuesday, July 16, 2013

Has global warming continued?

Enter "Has global warming" into a search engine, and the autocomplete function will suggest the word "stopped".

That we need to stop. Let's flip this around: "Has global warming continued?"

Yes. Global warming continues along, as this nice graphic from Climate Nexus shows so clearly.

The confusion is about surface temperatures. Over the past 10-15 years, the global mean surface air temperature did not increase at the rate of the previous decades. The cause of the slowdown is primarily natural variability, variability that is driven by long-term oscillations in the oceans. The planet is still adding heat - we can see in this planetary energy balance data. The difference is for the past few years, more of that heat is gathering in the deep ocean.

In a few years, the yin of deep ocean heating will give way to the yang of surface temperature warming. Among other things, we'll see full El Nino events develop again - there has not been one since the climate shifted in 1998, something my lab is studying - and with that, new global surface temperature records.


Florifulgurator said...

Over the past 10-15 years, the global mean surface air temperature did not increase at the rate of the previous decades.

The term "rate" makes no sense. It is obvious nonsense.

Just look at the curve. It is noisy, yet has a trend. From my purely visual inspection (using a transparent ruler to check the linear trend) I see nothing noticeable. The recent decade nicely balances the 1998 excursion. Looks like a straight line plus/minus noise.

Simon Donner said...

Agreed, of course, as the post says the "pause" is largely driven by natural inter-annual and decadal variability, which if you take the long view, could be considered noise. Because of the time-scale of that variability, if you take 10-15 year snapshots of data, you find a lower trend in the 2000s and early part of this decade, than in the 80s and 90s. If you step back and examine the whole record, you see the long-term trend, with the decadal and annual noise. That's the whole point. We are saying the same thing.

Florifulgurator said...

Of course I was sure you know. But the denialisti don't. Their "global warming has stopped" nonsense needs to be pointed out as straightforward nonsense, wherever you meet that nonsense. Some detailed explanations (ocean heat fluctuations etc.) may be given later, if they are still interested.

Simon Donner said...

Agreed, which was part of the inspiration behind inverting the question and stressing "continued".