Arguments
Global Surface Temperature: Going Down the Up Escalator, Part 1
Posted on 5 November 2011 by dana1981
One of the most common misunderstandings amongst climate "skeptics" is the difference between short-term noise and long-term signal. In fact, "it hasn't warmed since 1998" is ninth on the list of most-used climate myths, and "it's cooling" is fifth.
This myth stems from a lack of understanding of exactly what global warming is. The term refers to the long-term warming of the global climate, usually measured over a timescale of about 30 years, as defined by the World Meteorological Organization. This is because global warming is caused by a global energy imbalance - something causing the Earth to retain more heat, such as an increase in solar radiation reaching the surface, or an increased greenhouse effect.
There are also a number of effects which can have a large impact on short-term temperatures, such as oceanic cycles like the El Niño Southern Oscillation or the 11-year solar cycle. Sometimes these dampen global warming, and sometimes they amplify it. However, they're called "oscillations" and "cycles" for a reason - they alternate between positive and negative states and don't have long-term effects on the Earth's temperature.
Right now we're in the midst of a period where most short-term effects are acting in the cooling direction, dampening global warming. Many climate "skeptics" are trying to capitalize on this dampening, trying to argue that this time global warming has stopped, even though it didn't stop after the global warming "pauses" in 1973 to 1980, 1980 to 1988, 1988 to 1995, 1995 to 2001, or 1998 to 2005 (Figure 1).
Figure 1: BEST land-only surface temperature data (green) with linear trends applied to the timeframes 1973 to 1980, 1980 to 1988, 1988 to 1995, 1995 to 2001, 1998 to 2005, 2002 to 2010 (blue), and 1973 to 2010 (red). Hat-tip to Skeptical Science contributor Sphaerica for identifying all of these "cooling trends."
As Figure 1 shows, over the last 37 years one can identify overlapping short windows of time when climate "skeptics" could have argued (and often did, i.e. here and here and here) that global warming had stopped. And yet over the entire period question containing these six cooling trends, the underlying trend is one of rapid global warming (0.27°C per decade, according to the new Berkeley Earth Surface Temperature [BEST] dataset). And while the global warming trend spans many decades, the longest cooling trend over this period is 10 years, which proves that each was caused by short-term noise dampening the long-term trend.
In short, those arguing that global warming has stopped are missing the forest for the trees, focusing on short-term noise while ignoring the long-term global warming signal. Since the release of the BEST data which confirmed the global warming observed by all other global temperature measurements, climate "skeptics" have been scrambling for a way to continue denying that global warming is a problem, and focusing on the short-term noise has become their preferred go-to excuse.
The Noisy Group
Unfortunately, those making a lot of noise about the noise (and sweeping generalizations that global warming has magically stopped) include several "skeptic" and/or "lukewarmer" climate scientists, who really should know better. One of these, Judith Curry, is actually a member of the BEST team whose data has been used by climate "skeptics" as "proof" that global warming has stopped. Unfortunately, Dr. Curry herself fed these myths in a rather dismaying interview:
"There is no scientific basis for saying that warming hasn’t stopped...To say that there is detracts from the credibility of the data, which is very unfortunate...This is “hide the decline” stuff. Our data show the pause, just as the other sets of data do. Muller is hiding the decline"
Predictably, Dr. Curry's comments have been disseminated far and wide by climate "skeptics" who desperately want this myth to be true.
Dr. Roger Pielke Sr. has made similar claims in the comments on Skeptical Science:
"Since 2002, as shown in the lower tropospheric plot and in the upper ocean data, little of that heat has accumulated there. There is not enough melt of sea ice or glaciers to account for it there. "Global warming" has nearly stopped using these two metrics"
Dr. Roy Spencer has taken this argument to the extreme, claiming that based on one cool month in his University of Alabama at Huntsville (UAH) tropospheric temperature dataset, "the troposphere is ignoring your SUV" and that (perhaps sarcastically):
"While any single month’s drop in global temperatures cannot be blamed on climate change, it is still the kind of behavior we expect to see more often in a cooling world"
These climate scientists really should know the difference between short-term noise and long-term signal, and it's a travesty that they're misinforming the public, the media, and policymakers by conflating the two concepts.
The Signal Comes Through Loud and Clear
On the other hand, other scientists who understand statistics are doing an excellent job explaining the difference between signal and noise. For example, when asked if BEST showed that global warming had stalled over the last decade in response to the interview with Dr. Curry, Dr. Richard Muller (the BEST team lead) said:
“That’s incorrect...I mean, what they have done is an old trick. It’s how to lie with statistics, right? And scientists can’t do that because 10 years from now, they’ll look back on my publications and say, ‘Was he right?’ But a journalist can lie with statistics. They can choose a little piece of the data and prove what they want, carefully cutting out the end. If I wanted to do this, I could demonstrate, for example, with the same data set that from 1980 to 1995 that it’s equally flat. You can find little realms where it’s equally flat. What that tells me is that 15 years is not enough to be able to tell whether it’s warming or not. And so when they take 13 years, and they say based on that they can reach a conclusion based on our data set, I think they’re playing that same game and the fact that we can find that back in 1980, the same effect, when we know it [was] warming simply shows that that method doesn’t work. But no scientist could do that because he’d be discredited for lying with statistics. Newspapers can do that because 10 years from now, nobody will remember that they showed that.”
What the Science Says
The peer-reviewed scientific literature confirms Muller's comments. For example, Santer et al. (2011):
"Because of the pronounced effect of interannual noise on decadal trends, a multi-model ensemble of anthropogenically-forced simulations displays many 10-year periods with little warming. A single decade of observational TLT data is therefore inadequate for identifying a slowly evolving anthropogenic warming signal. Our results show that temperature records of at least 17 years in length are required for identifying human effects on global-mean tropospheric temperature."
and Easterling and Wehner (2009):
"Numerous websites, blogs and articles in the media have claimed that the climate is no longer warming, and is now cooling....We show that the climate over the 21st century can and likely will produce periods of a decade or two where the globally averaged surface air temperature shows no trend or even slight cooling in the presence of longer?term warming."
Not only are these short-term "pauses" just noise in the data, but observations show that they are entirley expected, and predicted by climate models (i.e. see Meehl el al. 2011).
Other Physical Evidence of Continued Warming
It's also important to point out that global temperature measurements aren't our only evidence of the long-term global warming trend. We've observed many physical indicators of global warming (Figure 2).
Figure 2: Physical Indicators of a Warming World
When is Warming Cooling?
When constantly confronted with this myth that global warming stopped in 1998, or 2000, or 2002, or 2005, or [insert year], we wonder why distinguishing between short-term noise and long-term signal is such a difficult concept for climate "skeptics." They remind us of the Penrose stairs made famous by M.C. Escher - a staircase which people can descend forever and not get any lower. This paradoxical perception of an impossible construction seems to be how climate "skeptics" view the world, which is undoubtedly why they're willing to risk our future on the hopes that 97% of climate scientists are wrong about climate science.
Part 2 of this post examines the "skeptic" explanation of how these cooling periods can add up to a net warming, and why that explanation is physically incorrect.
Note: this post has been incorporated into the rebuttals to "global warming stopped in [insert year]", and Figure 1 has been added to the SkS Climate Graphics Page
[DB] If you are indeed the same markx posting comments here as at Shaping Tomorrow's World (here, for example), please note that SkS has a Comments Policy forbidding sloganeering and accusations of deception. Moderation has already had to be enacted on your previous comments as a result (Note that similar to STW, all comments placed at SkS are audited for compliance).
Your referenced source is very shelf-dated. For OHC, Levitus et al 2012 is considered the more reliable source on OHC, as it contains actual data to December 2011, rather than on speculation.
Discussions of Earth's energy imbalance are more proper on a more appropriate thread (the Search function yields this as a suggestion). Off-topic comments will be removed. Thanks in advance for your compliance in this matter!
Sloganeering/intimations of impropriety snipped.
A thousand years ago Greenland is really green. There are farms and orchards. Today we can find there only polar grass. And according only by this fact all turmoil about accelerated global warming is meaningless.About average the problem is almost the same. Before 10 000 years the ice is at least 3000 kilometers south than today. That means average retreating of ice with 300 meters per year. We can speak about accelerated global warming only if the ice retreating is faster than 300 meters per year. Cheers.[DB] Please familiarize yourself with this site's Comments Policy; additionally, please read the Big Picture post.
Finally, commenting at Skeptical Science works best if you first limit the scope of your comment to that of the thread on which you post your comment and then follow up on those threads to see what respondents have said in response to you. There are quite literally thousands of threads here at SkS; if you do not engage with the intent to enter into a dialogue to discuss the OPs of the threads on which you place comments, you invite moderation of your comments.
Off-topic stricken out.
[DB] Please familiarize yourself with this site's Comments Policy; additionally, please read the Big Picture post.
Finally, commenting at Skeptical Science works best if you first limit the scope of your comment to that of the thread on which you post your comment and then follow up on those threads to see what respondents have said in response to you. There are quite literally thousands of threads here at SkS; if you do not engage with the intent to enter into a dialogue to discuss the OPs of the threads on which you place comments, you invite moderation of your comments.
Off-topic snipped.
It looks like Cliff Harris and Randy Mann decided to fire up Print Shop again and change the year on the 1998 peak to 2016.
The place where the temperature line crosses the baseline in is now somewhere between 2016 and the 2020s.
Is this progress?
http://www.longrangeweather.com/images/gtemps.jpg
As the result of a twitter conversation about this H&M graph I did some analysis which you might find interesting - feedback welcome.
https://climatechatter.wordpress.com/2016/12/16/comparing-data
[JH] Link activated.
As suggested, I am transferring comments from New Research to Climate Myth #65
Thank you MA Rodger and Eclectic for your help, but I am puzzled how the GHG effect for increasing Earth's surface temperature by 33 deg C ties in with Stefan-Boltzmann simple radiation calculations.
If we take the measured values of 0.297 and 0.612 for the Earth's albedo and emissivity respectively, and 342 Watts per square metre incoming energy from the sun, then we find energy balance at 288.5 K. Very good. This without mention of GHG effect. So I'm puzzled.
[PS] You are missing quite a few important details - starting with albedo.
Eddieb @138 ,
I'm not sure how your earlier comments came through to this thread, but things may as well stay here (unless the moderators wish to move it to Myth #65 or elsewhere). The listing of Climate Myths, on top left corner of every page, is numerical (for convenience of reference by readers) . . . but once you click on a Myth, and arrive at the thread, there's unfortunately no Number readily visible, to confirm that you have arrived at the correct destination.
Eddieb, it sounds like you would be aiming to get into the ground floor of self-education about "greenhouse" & related physics. It is not an intuitively obvious effect, and you need to learn and carefully think your way through the physical mechanisms involved (which concern the radiative physics of the "radiatively active gasses" ~ which is not at all like in a garden greenhouse, where the warming effect comes primarily from reduction of convective heat loss).
The Earth gains heat from solar radiation (of course!) and loses almost-precisely the same heat flux outwards into space, in the form of infra-red radiation (from the radiatively active gasses H2O, CO2, CH4, NO2, O3, etcetera). As very rough figures to remember, the outwards IR heat loss is : 60% from H2O; 30% from CO2, and 10% from the minor gasses.
I gather you are already somewhat aware of these actions, and the SB radiative formula. I am not clear where your uncertainty lies. Perhaps you are not separating the IR radiation from the Earth's surface . . . from the IR radiation from the upper atmosphere where the heat flux actually leaves the planet. Please excuse my usage of words like flux and heat and radiation and energy ~ in common parlance these are jumbled together and used rather unrigorously : but the underlying meanings are obvious enough when you think about the context.
Chase up the widely-known energy flux cartoon by Trenberth et al. It shows the influxes, outfluxes, reflectances, convections, H2O-phase-changes, back-radiations etc.
Commonly, scientists talk about the planetary heat loss as occurring at Top Of Atmosphere [ TOA ] but the TOA outwards flux is not happening at a narrow precise altitude (e.g. 6023 meters or whatever). It is happening at a band of altitude, varying with latitude and season etc., and is happening at a different band for H2O, a different band for CO2, a different band for CH4, and so on.
Between the solid surface and the TOA, is where the "greenhouse" effect occurs. I could give you a neat analogy with football players doing running exercises . . . but my post here is already rather too long.
Have a look at some of the eye-catching Climate Myths, which are great for doing some piece-meal self-education on climate science.
If you wish to "relax" while gaining info, then I recommend the Youtube videos by Potholer54. There are a couple of dozen or so of them [and a separate series debunking Anti-Evolution]. Potholer54 is a science journalist, who presents his info as based not on opinion by Talking Heads & Propagandists , but based on the actual science demonstrated in peer-reviewed papers from reputable science journals. His videos (usually about 10 minutes long) educate you somewhat indirectly, by meticulously debunking all the nonsenses coming from "the usual suspects" such as Moncton, Ball, Youtuber pundits, and even Al Gore too. Debunking, with listed references so you can check yourself on what he himself has said ~ and check on the misinformation / propaganda / downright deliberate porkies spouted by the anti-AGW brigade.
I recommend Potholer54, because I believe it is likely you will find his videos informative and vastly amusing in their humorous style. Entertainment +++
[PS] Energy balance diagram can be found here. Science of Doom has detailed walk through the calculations here.
eddieb @138,
To address your puzzlement directly, the Stefan-Boltzmann equation with albedo to reduce insolation accounted for - this does produce the 255K a global temperature. By adding the emissivity term at the value you use, the result is 288K, the average temperature of the global surface, rather than the effective temperature of the atmosphere at the altitude which emits energy to space. I think you will find that the value for emissivity you use, 0.612, is derived and used as an expression of the 33K GHG effect and is not a measured value.
The use of the emissivity term in Stefan-Boltzmann for use in a climate model is fraught will difficulty. The added complexity is not worth the effort, not least because emissivity considerations will be heavily wavelength-dependent and absorbivity (involving reflectivity/transperancy) also enters the mix. I would be happy to explain these difficulties further, but it is a dead-end in global climate modeling without entering the very-complex.
Thank you again, MA Roger and Eclectic, for your help. Very interesting.
eddieb
eddieb:
Let me try to give another explanation. First, emission of radaition is given by Planck's Law, which tells you how much radiation is emitted at any wavelength, as a function of temperature and emissivity. Emissivity is correctly applied at a specific wavelength, not across all wavelengths as it is typcially used in the Stefan-Boltzman law. However, for solids and liquids, emissivity is usually fairly constant over a wide range of wavelengths, so it is not a bad approximation to treat it as a constant in some cases.
The Stefan-Boltsman law is the sum total of all radaition emitted at all wavelengths - essentially, the area under the curve described by Planck's law.
Now, to get back to your comment at #138. The earth's surface temperature is about 288K, as you describe. The surface emissivity in the infrared is not as low as you have suggested though - in fact, most natural surfaces are close to 1:
https://www.thermoworks.com/emissivity_table
So, a surface at 288K would emit something like 390 W/m2 - much more than the 240W/m2 that balances absorbed solar radiation. The issue is that the surface can't emit this all directly to space - the atmosphere blocks this.
THere are two ways to resolve this in the Stefan-Boltmann model:
Both of these are pretty simplistic descriptions of what is happening, because the atmosphere does a lot of things other than radiation, but the basic ideas are sound: the atmosphere prevents the earth surface from emitting IR to space like a black body, and what does reach space is usually emitted at high altitude.
I hope this helps.
This is eddieb.
Thank you, Bob Loblaw, for your very interesting and helpful contribution.
AEBanner
I still find the "Going down the up escalator" graph to be very useful. In a way, I prefer it to the rebuttal to "It's cooling" climate myth rebuttal. I wish there was a more up-to-date version. In fact, it would be nice to do this and even add citations to the escalator figure (like Svensmark — I had to click his linked name in the rebuttal article to go to the archived WUWT to see that he made the claim of cooling 12 years ago). Is anyone interested in building an automatically updated version? (Out of my league on a technical level, I'm afraid.)