Update on the relationship between the NINO3.4 and global SSTa

More than fifteen months ago I wrote the post “What of the Pause?”, where I tried to analyse the state of the global climate with a special focus on the interesting developments following the 2011/12 La Niña. I have also later discussed that particular time period here.

I have earlier pointed out the close connection between the SSTa in that central-eastern part of the narrow Pacific equatorial zone called “NINO3.4” and “global” SSTa over decadal time frames, how the former consistently seems to lead the latter in a tightknit relationship, firmly constraining the progression of global mean anomalies through time – flat (though with much noise) as long as the NINO3.4 signal remains strong enough to override (and/or control) all other regional signals around the globe, which most of the time it does.

I have then proceeded to show how “global warming” (or “global cooling”) only appears to come about at times when the influence of this tight relationship on the global climate is somehow offset by surface processes elsewhere, meaning outside the NINO3.4 region. This obviously doesn’t happen too often, because it would take a very powerful and persistent process to disrupt and even break the sturdy grip of the NINO3.4 region on the leash with which it controls the generally flat progression of global mean temps over time.

In fact, from 1970 to 2013 it evidently only happened three times. Which means that within these three instances of abrupt extra-NINO surface heat is contained the entire “global warming” between those years. Before, between and after, global temp anomalies obediently follow NINO3.4 in a generally (though pretty noisy) horizontal direction; no intervening gradual upward (or downward) divergence whatsoever.

With the year 2015 completed, I felt an update of this NINO3.4-global SSTa relationship was in order. Is there evidence of a new step as of late …?

My answer to this can only be: ‘It is still too early to tell.’ But interesting things have happened – and are indeed still happening – over the last two to three years, since about mid 2013:

NINO vs. gl

Figure 1.

Continue reading

“The Blob” and global SSTa since 2010

Global SSTa has really been ratcheting up now for a while. At the moment, the strong ongoing El Niño is doing most of the work, but there is no question that even this has been provided with a significantly elevated baseline from which to soar, a raised mean level seemingly establishing itself already years before the current El Niño started moving.

Well, it just so happens that this new level is higher than the old one by quite exactly 0.1 K. How can one tell?

Like this …

We noted and discussed already a year ago how the global lower troposphere has yet to respond to the conspicuous and mostly extratropical accumulation of surface heat in the NE Pacific basin starting in mid 2013.

Under the working hypothesis that this abnormal and persistent NE Pacific surface heat phenomenon (often simply nicknamed “The Blob”) is responsible for the entire 0.1K lift in the mean level of global SSTa since 2013, and positing that the lower troposphere has not yet responded to it, hence giving rise to the distinct divergence seen over the last couple of years between the “gl SSTa” and “tlt” curves, we lower the former en bloc by 0.1K from July 2013 onwards (yellow vertical line in Fig.1) and superimpose it on the latter: Continue reading

‘Noise + Trend’?

Judith Curry just recently asked the following question in her blog post “The 50-50 argument”:

“So, how to sort this out and do a more realistic job of detecting climate change and (…) attributing it to natural variability versus anthropogenic forcing? Observationally based methods and simple models have been underutilized in this regard.”

There is a very simple way of doing this that people at large still seem to be absolutely blind to. To echo the words of ‘Statistician to the Stars!’ William M. Briggs: “Just look at the data!” You have to do it in detail. Both temporally and spatially. I have done this already here, here and here + a summary of the first three here. In this post I plan to highlight even more clearly the difference between what an anthropogenic (‘CO2 forcing’) signal would and should look like and a signal pointing to natural processes.

Curry has many sensible points. She says among other things:

“Because historical records aren’t long enough and paleo reconstructions are not reliable, the climate models ‘detect’ AGW by comparing natural forcing simulations with anthropogenically forced simulations. When the spectra of the variability of the unforced simulations is compared with the observed spectra of variability, the AR4 simulations show insufficient variability at 40-100 yrs, whereas AR5 simulations show reasonable variability. The IPCC then regards the divergence between unforced and anthropogenically forced simulations after ~1980 as the heart of the their detection and attribution argument. (…)

The glaring flaw in their logic is this.  If you are trying to attribute warming over a short period, e.g. since 1980, detection requires that you explicitly consider the phasing of multidecadal natural internal variability during that period (e.g. AMO, PDO), not just the spectra over a long time period. Attribution arguments of late 20th century warming have failed to pass the detection threshold which requires accounting for the phasing of the AMO and PDO. It is typically argued that these oscillations go up and down, in net they are a wash. Maybe, but they are NOT a wash when you are considering a period of the order, or shorter than, the multidecadal time scales associated with these oscillations.

Further, in the presence of multidecadal oscillations with a nominal 60-80 yr time scale, convincing attribution requires that you can attribute the variability for more than one 60-80 yr period, preferably back to the mid 19th century. Not being able to address the attribution of change in the early 20th century to my mind precludes any highly confident attribution of change in the late 20th century.

And Continue reading

‘Modern Global Warming’ in three steps – the (fairly) short version

In IPCC’s Fifth Assessment Report (AR5) of last year, they stated the following:

“It is extremely likely [95 percent confidence] more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.”

‘More than half.’ That sounds like a pretty conservative guess. Well, they end up going further than that. Much further.

What caused global warming over the last 60 years or so, according to the IPCC? Apparently, human ‘greenhouse gas’ emissions alone (100%):

“The best estimate of the human-induced contribution to warming is similar to the observed warming over this period … The observed warming since 1951 can be attributed to the different natural and anthropogenic drivers and their contributions can now be quantified. Greenhouse gases contributed a global mean surface warming likely to be in the range of 0.5°C to 1.3 °C over the period 1951−2010, with the contributions from other anthropogenic forcings, including the cooling effect of aerosols, likely to be in the range of −0.6°C to 0.1°C.”

That should be a net range of anthropogenic ‘contributions’ to the general global temperature rise between 1951 and 2010 of 0.6 to 0.7°C.

So, then, what did not contribute at all (0%) to that same general warming, according to the IPCC? Apparently, natural external factors like solar activity, and natural internal factors like ocean cycles:

“The contribution from natural forcings is likely to be in the range of −0.1°C to 0.1°C, and from internal variability is likely to be in the range of −0.1°C to 0.1°C.”

That should make up a total natural contribution to the general global temperature rise between 1951 and 2010 of exactly 0°C. Continue reading

How the world really warmed …, Part III: Steps 2 & 3

”The main tool used in this study is correlation and regression analysis that, through least squares fitting, tends to emphasize the larger events. This seems appropriate as it is in those events that the signal is clearly larger than the noise. Moreover, the method properly weights each event (unlike many composite analyses). Although it is possible to use regression to eliminate the linear portion of the global mean temperature signal associated with ENSO, the processes that contribute regionally to the global mean differ considerably, and the linear approach likely leaves an ENSO residual. We have shown here that 0.06 °C of the warming from 1950 to 1998 can be accounted for by the increased El Niño phase of ENSO. The lag of global mean temperatures behind N3.4 is 3 months, somewhat less than found in previous studies. In part, this probably relates mostly to the key ENSO index used, as the evolution of ENSO means that greater or lesser lags arise for alternative indices that also vary across the 1976/1977 climate shift.”

From Trenberth et al. 2002: “Evolution of El Niño-Southern Oscillation and global atmospheric surface temperatures.”

I want you to bear this quote in mind – especially the highlighted part – throughout this post. Because what we will do in the following, is to address and track Trenberth’s ‘ENSO residual’, the result of ENSO-related oceanic/atmospheric processes operating and contributing regionally to global mean temps outside the ‘key ENSO index’ region in the equatorial East Pacific (the NINO3.4), and that evidently (according to the data) differ considerably in their effects (contributions) from some ENSO events to others. This extra-NINO part of the ENSO process is what caused ‘global warming’ since 1980. That’s not a claim. It’s an observation. It’s right there in the freely accessible real-world data. For all to see.

If one simply cares to have a look … And knows what to look for. Continue reading

How the world really warmed …, Part II: ‘Step 1’

We have identified three steps in mean global temperatures since 1970: one in 1979, one in 1988 and one in 1998. These three steps alone conspicuously and remarkably contain the entire modern era ‘global warming’ observed to occur between the late 70s and the early 00s, a period of about 20-25 years, depending on how you look at it. This means that outside these three distinct and sudden upward jolts, there has been no discernable ‘global warming’ going on at all for the duration of at least the last 50 years.

So how, then, did these three prominent steps in global temperatures come about?

It has long been known that the climate regime (the general state, arrangement and operative processes of the coupled ocean/atmosphere condition) of the Pan-Pacific basin changed fundamentally and abruptly in 1976/77. Many studies have documented this. Something big happened in the Pacific Ocean that year. This ‘thing’ has been dubbed ‘The Great Pacific Climate Shift’ (GPCS). Continue reading