Guest Post by Bob Tisdale
In Dana Nuccitelli’s recent post at SkepticalScience Matt Ridley wants to gamble the Earth’s future because he won’t learn from the past, he has finally admitted something we’ve been discussing for more than 6 years. (His article was also cross posted at The Guardian here. Yes, that’s the zombie post that has gained so much attention.)
Dana admitted that during a decade-long (or multidecadal) period(s) when El Niño events dominate (when El Niños are stronger, last longer and happen more frequently), the El Niños enhance global warming, and during periods when La Niña events dominate (when there are weaker, shorter and fewer El Niño events), the absence of El Niño events suppresses the warming of global surfaces.
I am not commenting on the rest of Dana’s post. I’ll leave that for you. I’m only commenting on a very small portion of it.
I was somewhat amazed by Dana’s admission that stronger and longer El Niño events can enhance global warming.
Dana quotes Matt Ridley in his post and then responds to what Matt wrote with (my boldface):
This is incorrect – average global surface temperatures have warmed between 0.6 and 0.7°C over the past 40 years (lower atmospheric temperatures have also likely warmed more than 0.5°C, though the record hasn’t yet existed for 40 years). During that time, that temperature rise has temporarily both slowed down (during the 2000s, when there was a preponderance of La Niña events) and sped up (during the 1990s, when there was a preponderance of El Niño events). Climate models accurately predicted the long-term global warming trend.
El Niños didn’t only dominate during the 1990s. For some reason known only to Dana, he overlooked the fact that the 1976/77 El Niño started the period when El Niño events dominated the late 20th Century. Thus, using Dana’s logic, El Niño events enhanced the observed global warming from the mid-1970s to the turn of the century—the first 25 years of the past 40 years Dana chose for his discussion.
There is, of course, a major problem with Dana’s last sentence in that quote:
Climate models don’t consider the ENSO-enhanced portion of the global warming from the mid-1970s to the turn of the century. See Figure 1, which compares observed global surface temperature anomalies for the past 40 years to the model simulations of global surface temperatures. We’re presenting the model mean because it best represents the forced component of the climate models. (See the post here for a further discussion about the use of the model mean.)
The climate modelers assumed that all of the global warming occurred because of manmade climate forcings. That is, the modelers did not consider the portion of the warming from 1975 to the turn of the century that was caused by the dominance of El Niños. But then, according to Dana’s representation, there was a slowdown in surface warming caused by the weakening of El Niños. The result of the slowdown: the models are rapidly diverging from reality. In short, the models did not account for the enhanced warming caused by El Niños and they failed to consider that a period without strong El Niños would suppress global warming.
Additionally, climate models simply extend (and accelerate) out into the future the El Niño-enhanced warming rate of the mid-1970s to the turn of the century. It’s pretty obvious to all but the logic-impaired that climate models have projected too much warming.
(For more evidence on how poorly climate models simulate surface temperatures, see the post Alarmists Bizarrely Claim “Just what AGW predicts” about the Record High Global Sea Surface Temperatures in 2014.)
Yet, skeptics are ridiculed when they write that global warming occurs during multidecadal periods when El Niño events dominate…because of the El Niño events. Example: I’ve included the following statement from the introduction to my book Who Turned on the Heat? in a number of posts in recent years. I’ve amended it with bracketed phrases for this post.
Climate models used by the Intergovernmental Panel on Climate Change (IPCC) cannot match the sea surface temperature records that show how often and how strongly ENSO events have occurred since 1900. Climate models can’t even simulate the ENSO events since the start of the recent warming period in the mid-1970s. However, the models need to be able to mimic the historical instrument-based ENSO records. In fact it’s critical that they do, and it’s easy to understand why. The strength of ENSO phases, along with how often they happen and how long they persist, determine how much [sunlight-created] heat is released by the tropical Pacific into the atmosphere and how much [sunlight-created] warm water is transported by ocean currents from the tropics toward the poles. During a multidecadal period when El Niño events dominate (a period when El Niño events are stronger, when they occur more often and when they last longer than La Niña events), more [sunlight-created] heat than normal is released from the tropical Pacific and more [sunlight-created] warm water than normal is transported by ocean currents toward the poles—with that warm water releasing heat to the atmosphere along the way. As a result, global sea surface and land surface temperatures warm during multidecadal periods when El Niño events dominate. They have to. There’s no way they cannot warm. Conversely, global temperatures cool during multidecadal periods when La Niña events are stronger, last longer and occur more often than El Niño events. That makes sense too because the tropical Pacific is releasing less heat and redistributing less warm water than normal then.
End of quote from Who Turned on the Heat?
The CO2-obsessed become incensed when I include that paragraph in a post.
NOTE: If you need a reference for the “sunlight-created” heat and warm water, see the quotes from the two Trenberth papers under the heading of Trenberth’s Conflict in the post The 2014/15 El Niño – Part 9 – Kevin Trenberth is Looking Forward to Another “Big Jump”. [End note.]
OOPS! DANA FORGOT THE AMO
Dana Nuccitelli also overlooked the contribution of the Atlantic Multidecadal Oscillation to global surface warming over the last 40 years. Figure 2 compares the modeled and data-based Atlantic Multidecadal Oscillation (AMO), using the Trenberth and Shea (2006) method to determine the Atlantic Multidecadal Oscillation, in which global sea surface temperatures (60S-60N) are subtracted from the sea surface temperatures of the North Atlantic (0-60N, 80W-0). Trenberth and Shea used sea surface temperature anomalies, but I’ve presented temperatures in absolute form. Obviously, the Atlantic Multidecadal Oscillation is not a forced component of the climate models, and as a result, the contribution of the Atlantic Multidecadal Oscillation to the warming over the past 40 years is not considered by climate models.
Some of you may recognize Figure 2. It was recently presented as Figure 25 in the post Alarmists Bizarrely Claim “Just what AGW predicts” about the Record High Global Sea Surface Temperatures in 2014.
For more information on the Atlantic Multidecadal Oscillation, refer to the NOAA Frequently Asked Questions About the Atlantic Multidecadal Oscillation (AMO) webpage and the posts:
- An Introduction To ENSO, AMO, and PDO — Part 2
- Multidecadal Variations and Sea Surface Temperature Reconstructions
That NOAA FAQ webpage confirms that the Atlantic Multidecadal Oscillation can contribute to global warming and suppress it.
CLIMATE MODELS ARE OUT OF PHASE WITH REALITY
So we have two natural modes of multidecadal variability that enhanced global surface warming from the mid-1970s to the turn of the century. (We won’t know for a decade or more if the Atlantic Multidecadal Oscillation has, in fact, peaked already.) Unfortunately the climate models do not consider the enhanced warming from ENSO or the AMO; that is, the models assume that all of the warming from the mid-1970s to the turn of the century was driven from manmade greenhouse gases. As a result, their projections of future global warming are way too high.
The standard argument now from the CO2 obsessed is that over multidecadal time periods the natural enhancements and suppressions of global warming will cancel out because ENSO and the AMO are oscillations. Unfortunately, as we’ve noted, the models align with the warming during a period when that warming was enhanced by two modes of natural variability, and the models fail to consider the multidecadal suppression of warming…for the next couple of decades and any future suppressions of warming.
In other words, the models are out of phase with reality. There’s nothing new about that statement. Skeptics have been pointing that out for years.
For example, Figure 3 illustrates a sine wave with a 60-year frequency. That will represent our data. It is arbitrarily scaled…in other words, it is not scaled to surface temperatures. The maximums occur at 1885, 1945 and 2005, while the minimums occurred at 1915 and 1975. That roughly aligns with the multidecadal variations in the surface temperature record from 1885 to present. Continuing the 60-year cycle into the future gives us another minimum at 2035, the next maximum at 2065 and yet another minimum at 2095. The red line shows a “model” that aligns with the trend from 1975-2005, and in a maroon dotted line, continues that “model” trend out into the future. As you can see, the model and projection bear no relationship with the underlying cyclical nature of the data.
That’s basically what the climate modelers have done. The models align with a naturally occurring upswing in surface temperatures and the modelers have failed to consider the future multidecadal variations in their projections caused by the natural enhancement and suppression of global warming.
KEVIN TRENBERTH’S “BIG JUMPS”
At this point in the post I would normally go into a discussion of ENSO acting as a chaotic, naturally occurring, sunlight-fueled, recharge-discharge oscillator. But it will be difficult enough for the CO2 obsessed to come to terms with Dana’s admission, so I’ll skip that part of the normal plotline. If you’re interested in learning how powerful El Niño events contribute to long-term warming trends, see the following Trenberth “big jump”-related posts:
- Open Letter to the Royal Meteorological Society Regarding Dr. Trenberth’s Article “Has Global Warming Stalled?”
- The 2014/15 El Niño – Part 9 – Kevin Trenberth is Looking Forward to Another “Big Jump”
Skeptics have been preaching for years that natural variability can contribute to the long-term global surface warming trend…and suppress it, in effect stopping it.
It was quite amazing to finally see one of the key members of the alarmist blog SkepticalScience (and global-warming reporter at The Guardian) finally admitting the same. Of course, Dana Nuccitelli forgot to advise his readers that “a preponderance of El Niño events” had “sped up” global surface warming from the mid-1970s through the 1990s, not just “during the 1990s”. He also forgot to mention that another mode of natural variability, the Atlantic Multidecadal Oscillation, had also contributed to the warming then.