What does "Global Warming" mean?

The Problem with terminology

There is some confusion about the way we talk about global warming. Most of this confusion arises during the communication of science to the public or to policy makers. Part of this confusion rests within the science itself; There is no meaningful confusion about the nature of global warming or how it is observed, but there are some terminological glitches of the kind that arise in science all the time, and that rarely matter to the science itself.

The most commonly used indicator of global warming is a graph that is meant to show the effects of global warming over time. This may be by decade, yearly, or monthly, or using a moving average using a period such as 12-months or some other time period. This is an example:

NASA GISS TEMP ANOMALY 1880-PRESENT

NASAGISS_Feb_2015_12Month_MovingAverage

The vertical axis is temperature anomaly, the standard way scientists measure changes in heat over time. Each data point is calculated from thousands of roughly head-height thermometers across the Earth’s land surface, combined with a measure of global sea surface temperatures. As we go back in time there are fewer data sources, and the sea surface temperature is measured differently. During any given year, there are parts of the globe that are underrepresented. The way these deficiencies in the data are addressed varies across the major data sets (from the US, Great Britain, or elsewhere) though all the different data sets use most of the same original raw data. This graph is based on the data provided by NASA’s Goddard Institute for Space Studies (GISS). All of the different data sets show the same thing, a general increase in global surface temperatures, and the variation over time, the up and down squiggles, is similar for all the data sets. They differ only in details.

It is an important fact that as the line indicating global surface temperature going up across the indicated time span, the amount it goes up varies. There are short periods of time when the temperature value goes up rather quickly then drops a bit, and there are periods of time during which the value goes up and down without much increase over several years running.

When we see a brief period (a few years, or a decade, etc.) where the trend varies from the long term trend, we need to ask why this is happening. Most of the dramatic upward spikes turn out to be El Niño years, when the ocean is adding a lot of stored heat into the atmosphere. Most of the periods where the rise in temperature value is somewhat lackadaisical are periods both lacking an El Niño event and having a number of La Niña events, during which the Pacific Ocean is soaking up more heat than average (that heat comes back out during El Niño periods).

There are also periods when the rise in global temperature is attenuated by additional aerosols in the atmosphere. This may be caused by a high rate of volcanic activity or the explosion of a particularly large volcano. Also, at one point, we see general increase in the upward trend that is probably a combination of a) cleaning up some of the human caused aerosols with the Clean Air Act and similar regulatory changes, and b) an increase in the human output of greenhouse gas pollution.

A significant cause in the variation of this signal over time, related to El Niño and La Niña events, is probably the result of one or more long term oscillations in the relationship between the ocean and the atmosphere. I’ve written about recent research addressing this phenomenon here. These multi-decadal oscillations probably explain most of the waviness in the line.

We have recently moved past a period of a relative slowdown in the increase in global surface temperature and are now experiencing a rapid rise in average global temperature. The way this slowdown is discussed is part of the confusion about global warming. To the average person, the term “slowdown” might sound like “decrease,” but it is not a decrease in surface temperatures, but a reduction in the rate at which surface temperatures are going up for a few years.

Nonetheless, the recent slowdown has been exploited by those who argue that global warming is not real, or is not, somehow, caused the way scientists say it is. It has been termed a “hiatus” or a “pause.” This terminology is problematic. A hiatus is a gap. When we “pause” something (like using a pause button) we stop it. The stop button on your music device stops the music. The pause button also stops it. The difference between stop and pause is what happens after you restart it, or a difference in the internal working mechanism. In the old days, for example, if you stop an audio or video tape, the magnetic head that reads the data is lifted off the tape, but if you hit “pause” the magnetic head stays on the tape so restarting is smoother. (If you pause for too long the magnetic head can damage the data on the tape!) Thus, “pause” and “stop” are functionally the same thing when it comes to whether or not the music or video is playing. A “pause” in global warming would be a stop in global warming. That, however, did not happen.

A hiatus or a pause in global warming is at present physically impossible. Our climate system operates in such a way that increasing the amount of human generated greenhouse gas pollution, all else being equal (or more or less equal), will increase the global heat imbalance and force the surface temperatures upwards. The implication of a “pause” or “hiatus” (stopping, or a gap in, warming) is that global warming is not happening for a period of time, as though the physical process stopped working, and the implication of that is that physics does not work the way climate scientists know it works. This is why “pause” is so beloved a meme in the denier community. If there is a pause, the science must be wrong. But even if there were sufficient aerosols from a huge volcanic eruption to actually lower global surface temperatures significantly for a short time, the greenhouse gasses previously and continuously added by humans would remain and continue to exert an upward effect on temperature. Once the aerosols settle, which does not take long, the added greenhouse gasses will remain for many decades (even centuries) and warming will continue until an equilibrium is reached. That would not be a pause or hiatus, just a bit more wiggling in the line marching ever upward.

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Book suggestions: For a good overview of climate change, see "Dire Predictions." For a good overview of climate change denialism, see "Climatology vs. Pseudoscience."

Process vs. pattern


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Global warming is a process. More greenhouse gasses along with the resulting positive (heat increasing) feedback effects that accompany that increase cause a heat imbalance and the parts of the Earth that can absorb heat from the sun directly or indirectly become warmer. Global warming is also a pattern. It is a pattern we observe in the average global temperature measures such as the surface temperature measurement described above.

If you can show that the pattern as observed is not as expected, that would bring into question the process of greenhouse gas-caused changes in the Earth’s heat, right? Well, no. The answer is no because the way the process works and the way we generally observe the pattern are not the same thing.

Look at these two graphs.

OHC

Global Ocean Heat Content. Global Warming. Greg Laden's Blog

GMST

Screen Shot 2015-06-06 at 1.41.28 PM

The upper graph shows the temperature of the part of the ocean, the upper 700 or 2000 meters, that can be warmed indirectly by increasing greenhouse gas pollution over a period of time. The lower graph shows the same thing for the sea surface and the atmosphere. These graphs are dramatically different in the x-axis. The ocean heat content graph only goes back to the late 1950s, while the surface graph goes back to 1880. This is because of difference in the data that are available.

Now, have a look at this graph:

BUBBLE GRAPH SHOWING DISTRIBUTION OF HEAT IMBALANCE

Screen Shot 2015-06-07 at 12.14.22 PM

This graph shows the relative percentage of the overall warming that occurs in the ocean vs. the atmosphere and a few other systems. The ocean heat graph above, which shows no recent period of time during which heat does not go up, represents over 90% of the heat increase due to global warming. The surface represents only a small percentage. In the following graph, I simply cropped each of these two graphs to show only 1960 to the present, then scaled them so the surface graph and the ocean graph are in proper relationship to each other on the vertical axis. This is a bit hokey but it makes the point:

HYBRID GRAPH SHOWING GMST AND OHC SCALED

Screen Shot 2015-06-07 at 10.42.31 AM

Wow. When we refer to the process of global warming, we are referring to changes in the Earth’s heat balance, which is a combination of what climate scientists call “forcings” (not my favorite term but it is the one in use) that move heat imbalance either up or down. Human caused greenhouse gas pollution is a positive forcing, which in turn causes a number of other feedbacks, also positive. So the total result of greenhouse gas pollution is an increase in temerature over time until some future point where the forcing stops (because we stop using fossil fuels) and the heat imbalance eventually settles out (far into the future). Aerosols from other human pollution or volcanoes, etc., force in the opposite direction. The net outcome has been, for decades, an increase in temperature. The cobbed together graph above shows that all of the forcing combined has resulted in a steady upward increase in temperature. The graph also demonstrates that even large up or down deviations in the pattern of surface temperature are not especially relevant to the total process of warming.

When we refer to the pattern of global warming, however, we generally do not refer to overall changes in heat balance, but in practice, we refer to changes only in global means surface temperature. Why? Because that is the measure for which we have data over a long period of time. It is like this. Say you want to know if your child has a fever. You may put a thermometer in the child’s mouth, or some other orifice, or put a heat sensitive strip on the child’s forehead, or an ear thermometer in the ear. In so doing, you have measured the child’s temperature, right? Well, no. What you measured is the temperature of the child’s mouth, or distal large intestine, or forehead, or ear drum. You don’t call the nurse hot line and say, “Help, my child’s mouth is 104 F, what do I do?” You use the measurement you took of one tissue or body part to estimate the child’s overall body temperature. Well, actually, you use the measurement you took to see if your child’s temperature-related homeostasis is off. In any event, you used a measurement of a small part of your child’s body to estimate internal temperature.

When climate scientists show you a graph of mean surface temperature and talk about global warming, they are not ignoring the ocean. They are simply measuring the surface as an indicator of an ongoing change in the Earth’s heat imbalance, using data that are available, understood, and cover a long time period. So they are talking about the process of global warming (which involves the oceans, the air, the sea surface, the ground under your feet, ice, etc) but using a readily available and useful tool to track it.

As a result, the term “global warming” to many climate scientists means “overall positive heat imbalance most of which is in the ocean.” To some scientists, “global warming” refers to global mean surface temperature change, and the ocean is viewed as a reservoir where heat is stored, waiting in the pipeline to come out later. That is really the same thing, and both acknowledge the difference between surface temperature measurement and ocean heat content measurement. When you actually look in the published literature, you see no confusion or changes in terminology. You really don’t see the term “global warming” being used very often when referencing measurements. If the measurement being discussed is the heat in the ocean, you see the term “ocean heat content” (OHC). When the measurement being discussed is the surface temperature record, you see a term like “Global mean surface temperature” (GMST). And, you don’t even see these terms used on their own; At some point in the scientific paper, the actual data set used to derive these values is specified.

This does not imply that the difference between ocean heat content and global surface temperature is not important. It is very important. For one thing, we live at the surface. Heat waves are a phenomenon of the atmospheric temperature at the same location it is measured by all those thermometers. Tropical storms form more frequently or grow larger with a higher sea surface temperature. A warmer atmosphere holds more water. Relative changes at different latitudes in surface temperature appear to have changed how weather systems behave, giving us the phenomenon known as “weather whiplash” causing frequent droughts (short or long term) and regional inundation with exceptional rain or snow. The deeper (down to 2000 meters) heat in the ocean does not directly cause those things.

But, the heat in the ocean does contribute when it comes out, like during an El Niño, adding to the surface heat. And, there are other effects of heat in the ocean, causing important ecological changes including ocean acidification. It isn’t really that complex. Both the ocean (down to 2000 meters or so) and the surface (SST and the bottom of the atmosphere over land) are warming. The total amount of heat that the ocean can absorb is huge (because water holds more heat than air). The heat moves back and forth between the sea and the air. Numerous effects occur. The whole shebang together is global warming, but we often represent the phenomenon as changes in surface temperatures because that is an excellent measurement.

Perhaps we should not use the term “global warming” for the pattern of surface temperature changes, because global warming is bigger than that, it includes more stuff. But the surface is where we are at, and just like we say “my child has a fever” because our child’s forehead feels hot and the ear drum is verified as warmer than it should be with an optical thermocouple, we can refer to the GMST and speak of global warming. Because it is.

On several occasions, I have had lengthy discussions with colleagues who are full time well respected climate scientists about this terminology. As far as I can tell, two things are true: 1) left on their own, these scientist would probably sort out into two groups who prefer two different ways of using terms like “global warming” and “surface temperature” and such; and 2) this matters about as much as what color pocket protector they are using to hold their mini-slide rules. It does not matter at all. As discussed above, when doing the science, the systems to which one refers and the data one makes use of are specified unambiguously and differences in the way these terms may bleed out into public (and policy making) space are not important. Outside the science, in that public and policy making space, the terms do become important, but not because they have problems. They become important only because they are being used, exploited, by deniers of science to misdirect and mislead.

And, as I suggested at the beginning of this essay, this is normal. Terminological messiness occurs in all areas of science. I once copied out all of the glossary definitions of major phenomena in population genetics, from a well written textbook produced by a well respected population geneticists, into a handout. Every definition from that glossary contradicted or complexified at least one other definition. It was a mess. But it was also real. Each term had been introduced at a different time by different scientists for different reasons with different problems trying to describe something somewhat different. Had a committee of population geneticists sat down for two years, long after the science had been worked out in some detail, and generated a glossary of terms (like “bottleneck,” “genetic drift” and “founder effect”) there would be no contradictions or ambiguities (though there might be a few black eyes along the way). Even the term “gene” has multiple and often contradictory meaning in use, and that gets worse when dealing with the literature over a couple of decades. This emerged over time as we learned more about what a “gene” actually is. Yet, population geneticists and DNA experts do not have any problem doing the science. These are just quirks that emerge at the interface of the rational pursuit of truth in science and this crazy thing we have called language.

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Awesome post Greg, you are very good at "splainin" as Ricky Ricardo was wont to say. I sent the link to four of my fellow environmental science faculty members.

By Robert Powell (not verified) on 07 Jun 2015 #permalink

Thanks for your patience in unraveling this stuff, very impressive. Here's a generic comment I've started using as appropriate, for what it's worth:

From a communications perspective, every time the p- or h- word is used, whether intentionally or unintentionally, it spreads the denier “meme” that there has been a p- or a h-. Word choice is really, really, really important (that is to say, it’s important :)) when attempting to convey anything to a general audience, and I think the science community, as well as many reporters, has let the public down by failing to be disciplined about the words used. (This is also true, by the way, even for clever formulations like Dr. Mann’s “faux pause.” Just don’t say the word.) In point of fact, it’s been a slowdown at most, so why adopt inaccurate denier terminology?

By climatehawk1 (not verified) on 07 Jun 2015 #permalink

I think this was a very good post on what global warming actually is.

@ # 2

Amen. This drives me nuts in perpetuity, since the damage has already been done.

You see this kind of thing a lot in blog comment sections, where the knee jerk impulse is to fly at deniers and trolls essentially on the field of battle as they define it. This may stem from scientists' tendency to want to quibble over niggling details and their lack of experience in dealing with the vast stock piles of toxic stupidity that culture warriors have at their disposal.

The thing to remember is that the field already belongs to science. You can afford to sit back for a few beats (at the very least) and approach the problem of invasive jackasses laterally and strategically... You know, instead of just flapping around the countryside like chickens with their heads cut off.

Don't let the damned bastards push you off balance!

By Obstreperous A… (not verified) on 07 Jun 2015 #permalink

I have heard from eg James Hanson, that the CO2 emitted thus far , ~400 ppm, not counting the ocean warming, has caused 0.8 degrees C warming on a global avg. and that from this 400ppm another 0.8 C is "in the pipeline". Thus 400 ppm is calculated to guarentee heating of 1.6 degrees C eventually; what is this prediction or calculation based on? I would ask James Hanson, only hes busy eating dinner.

By robert dresdner (not verified) on 07 Jun 2015 #permalink

Excellent article as usual Greg Laden - you've nailed it again. Spot on.

I've said before and will say again that the term 'Global Overheating' is a better more accurate description than "warming' because it conveys that there is a problem and that things are getting too hot rather than using the milder word which has generally pleasant connotations. I think a good acronym for the phenomenon - which, btw, someone else (Keith Bowden I think?) coined on the Phil Plait's old Bad Astronomy blog years ago - is HIRGO or Human-Induced Rapid Global Overheating which I'd love to see adopted by everyone because it plainly sums up the situation in the clearest way.

I'd also like to see positive and negative feedback replaced by 'escalating feedback' for +ive and 'stabilising feedback' because again, I think it makes it clearer and avoids confusion with words that imply things which muddy the minds of non-scientists. That's why I'm keeping up my efforts to use HIRGO etc ..

(Plus, on an unrelated issue, 'Ouranos' the more accurate name for the only planet named for a Greek as opposed to Roman god.)

Yes, it doesn't change the science or physical reality but the
language used is important in shaping public perceptions and is one area where the Deniers have been able to really exploit and hammer home their disinformation and spin as #2climatehawk1 has noted. I also agree with that comments point about the use of 'slowdown' too. How we describe things can have a huge influence and power over our thinking and responses to them as people like George Orwell have long noted.

I hope this can help make a difference and request that people think about taking up some of these suggestions please.

By Astrostevo (not verified) on 07 Jun 2015 #permalink

Greg,

Sorry to be nitpicking on your analogies again, but the fever thing spoils an otherwise pretty accurate exposition. The forehead test and the thermometer are the fever; they are proxies for an underlying condition (e.g. infection). The infection is the analog to system energy anomaly, and the fever is the analog to GMST.

I would also say that the fever is itself a poor analog because it is not an average over a widely varying range of sub-system measurements.

GMST is a convenient proxy, but not, as we have seen with the endless and pointless hiatus debate, a clear one.

Republicans and people who don't give a schite but are in various power points.....Fingers in ears and eyes closed, and seating on their precious wallets screaming "LaLaLaLaLa....it aint real!!!" Because they want theirs now and and as just stated don't give a schite about after they die. Remember most people in high power are sociopaths that's how they get their. Until we can vote them OUT there will be little done!!
And I agree this was a very good clear posting on the subject. And I have argued this with many rePUKEians and the above is a common response.

robert dresdner: The total amount of warming from a given amount of CO2 added is usually expressed as the simpler question of how much will the surface temperature go up with a doubling of pre-industrial levels. That number would be reached several years after the adding of the CO2 because it takes time (mainly because the oceans are taking up much of the heat). There are so many variables each of which have a range of possibilities and generally interact that it is difficult to calculate. JH's estimate is within the range of what others say.

Here is a pretty good discussion of this question: http://www.skepticalscience.com/climate-sensitivity-unlikely-less-than-…

Zebra, Imma stand by my analogy. The purpose of the analogy is to explore the question of how we measure temperature of something, so the analogy examines measuring the temperature of a planet and measuring the temperature of a child. In both cases there could be a range of underlying causes of the changes in temperature (your underlying conditions).

Here's the thing about analogies. If you try to make them "perfect" then you will end up talking about something else, which is different. That makes the analogy weak because the differences are ... well, different.

But yes, exactly: GMST is a proxy for overall warming. But it is also a relevant measure in itself because surface temperature itself is a factor that causes a number of things we are interested in.

Since we are talking about proxies, it is also relevant that we are never really measuring temperatures. We are measuring the effect of heat at various levels on materials (liquids in a traditional thermometer, the behavior of polymers at different temperatures, etc.). Everything is a proxy!

Greg,

You are way off here. There is no meaningful "planetary temperature", and GMST doesn't "cause" anything. Very, very wrong.

There is an increase in the energy content of the climate system.

You seem to pay lip service to that concept, but then go back to the naive conflation of it with "temperature" and "warming". You are falling into exactly the confused thinking/terminology you (almost) successfully clarified.

Changes in the state of GMST is the main cause of most of the effects of global warming we are seeing. I'm not sure what a "Planetary temperature" is (I did not use that term, you did) but I was referring to the overall heat imbalance in the half-dozen or so places it is observed. I used "planet" as a shortcut in a comment on a blog post. This is me speaking English to clarify a point and you being something of a pedant!

When we refer to warming, as in global warming, we are referring to heat, a form of energy, in the climate system. The measurement of heat is often called a temperature. When it goes up it is called warming. Up to the point when you told us that heat, temperature, warming, etc. are unconnected and should not be "conflated" there was not a lot of need for clarification.

And your attitude sucks and I'm not in the mood for it. And you don't understand what an analogy is.

Greg,

It's your blog and you are free to ignore non-affirmative inputs. But I thought the whole point of this post was the problem of accurate communication.

As I've pointed out in the past, and I think #2 and #4 would support, getting these essential physics concepts wrong has been, from the beginning, a very big problem in the public debate. What am I supposed to do, give people "on my side" a pass when they basically acquiesce to the Denialist's misconceptions and misrepresentations?

Zebra, I am ignoring inputs that lack no clear value. Non-affirming does not mean correct or relevant.

Everyone agrees that getting the science wrong has been a problem. Perhaps somewhere in your commentary you have something to offer. You might want to spend some effort on making yourself clear.

Zebra, you're not feeling' me (re: #4).

Analogies are instructive aids not parts of chains of evidence, so to speak -- for example in classrooms it's standard to compare electricity to hydraulics (and vice versa as I recall from hydrogeology).

In the whole history of the universe there has never been a perfect analogy, because you are comparing DIFFERENT things. I'm always baffled by people who don't get how analogies function, when they're strong or weak, and what you should and shouldn't try to extract from them.

This can be a problem with denialists; everything is a problem with denialists. But I'm more concerned with addressing how dense language is misunderstood/exploited by people who have poor reading or auditory comprehension.

By Obstreperous A… (not verified) on 08 Jun 2015 #permalink

From above:

"...you are very good at 'splainin'..."
"...on what global warming actually is..."
"...you've nailed it again..."

My own paraphrase (parapraise?) would be that...you write as if you just learned it.

However characterized...with a remembrance of what it was like not to know...questions you had...how things fit together...how you learned it.

And wherever it comes from...the literal situation...or a good memory. From a teacher's attitude or training. Or just a wider overall perspective.

Once just the interest of weather enthusiasts, the urgencies of climate science have made newbies of a lot of us - not always ready for realclimate.

By Same Ordinary Fool (not verified) on 08 Jun 2015 #permalink

Thanks for the great explanation Greg. Maybe things would have been clearer from the start if everyone (well the deniers wouldn't) had only used the term global climate change. That would have made throwing snowballs onto the Senate floor even more absurd than it was :)

By Doug Alder (not verified) on 08 Jun 2015 #permalink

I can understand the semantic difficulty with the general public and thanks, Greg, for teasing aspects apart. But many fields have terms which when aired in public can be confusing, e.g., "lapse rate", "adiabat", "top of atmosphere", "glacial rebound", "thermosteric sea level height": You get the idea. Greg acknowledged the "terminological messiness". Engineering has these, too (e.g., "impulse response").

I've always thought of and explained "global warming" as meaning greater mean energy density in the skin of the planet (oceans + atmosphere + soils + biosphere).

By Jan Galkowski (not verified) on 08 Jun 2015 #permalink

#18 Jan,

I have been trying to get people to think "energy" for decades now, so you make two. I hope you've had more success than I. But you also provide a good example for what I'm trying to get across to Greg-- The language is the physics.

What exactly is meant by "energy density"?

Is is energy/mass or energy/volume?

Big difference in usage. And there's no way, if my concern is to better educate the public, that I can let that pass.

Greg, I know what he (and you) are trying to say, but that is the result of "preaching to the choir"; it isn't necessarily good teaching for the beginner.

Glossing over essential facts is not doing the student any favors, and it is condescending. Temperature measurement of a gas by the expansion of a column of mercury is not "a proxy" in the way that GMST is a proxy, and, what makes it important, is that that fallacy is the basis for much of the Denialist argument.

I'm happy to elaborate on this point if I haven't been clear or you disagree.

#19 Zebra. The interpretation of energy density depends upon the substance. For water, by coincidence or standard, energy/mass or energy/volume are pretty interchangeble. Even for rock (granite) it's still interchangeable within an order of magnitude (3 gm/cm^3). For atmosphere, it gets complicated.

By Jan Galkowski (not verified) on 09 Jun 2015 #permalink

In reply to by zebra (not verified)

There are several problems here including the fact that these particular technical points are not the issue we are discussing. Rather than glossing over essential facts we are acknowledging important nuances that allow us to match the public/policy conversation better, at a certain level, to the conversation among scientists.

And Zebra, you really do have a problem with understanding parallelisms, analogies, etc. Revealed again here by your failure go get my comments about "proxies."

Please feel free to elaborate but you should probably reverse back into the ground you have already covered and be more thoughtful about that first.

Since we are talking about proxies, it is also relevant that we are never really measuring temperatures. We are measuring the effect of heat at various levels on materials (liquids in a traditional thermometer, the behavior of polymers at different temperatures, etc.). Everything is a proxy!

"We are never really measuring temperatures."

"We are measuring the effect of heat on materials."

I'm not "not getting" this, I'm saying that you are incorrect.

You are confusing "heat" and "energy". Heat refers to the transfer of energy. Heat doesn't have an "effect" on materials; heating them does.

Now, we can make an esoteric argument that "you can't really measure temperature", but, unlike the distinction between heat and energy, it isn't relevant at the level of the climate and "warming" issues we are discussing. We use temperature just like any other "measurement" in our application of thermodynamics.

So I will repeat: GMST is a proxy, not a measurement in the conventional sense. You cannot determine causally, from the value derived, any outcome for the system.

@19. zebra : "The language is the physics."

Umm, no, no it isn't.

The physics is the physics and the language is how we express our understanding of that physics in linguistic symbols.

By Astrostevo (not verified) on 09 Jun 2015 #permalink

Temperature measurement of a gas by the expansion of a column of mercury is not “a proxy” in the way that Temperature measurement of anything by the variation of electrical resistance of a platinum wire, or the thermoelectric potential between chromel and alumel, or the microwave emission of oxygen, or the difference in thermal expansion between two different solids, or the forward voltage drop of a silicon diode, or the small difference in the ratio of oxygen isotopes in ice.

So what.

By the way, mercury thermometers are actually measuring the difference in thermal expansion between a volume of mercury and its container made of a particular type of glass by eyeballing the position of the end of a connected column of mercury. Most people don't know the what or why of an immersion thermometer. either.

By Brian Dodge (not verified) on 09 Jun 2015 #permalink

Brian #21,

Right, none of those are "proxies" in the same way that GMST is a proxy.

What am I missing-- do you think you are disagreeing with me or what?

Hey thanks Greg for your reply to my query. I have another easy question: in light of all the feedbacks and tipping points, how much time before the Earth passes 2 degrees C [global mean]?

thanks in advance!!

By robert dresdner (not verified) on 09 Jun 2015 #permalink

A further elaboration on my point for Greg, also in response to robert dresdner:

"Changes in the state of GMST is the main cause of most of the effects of global warming we are seeing."

But that's simply not the case.

GMST, first of all, isn't a "state", it is an average value derived from what might properly be called a "state"-- the distribution of temperatures over the surface. That distribution could be conveyed in a map, for example. But the average doesn't tell us anything about that distribution.

So, it can't possibly be a "cause" of any effect-- obviously, there could be a cold winter in Boston and warm in Alaska, or vice versa, with the same GMST.

Referring back to my previous comment-- I can measure the temperature of a gas, and use that to calculate the pressure in a fixed volume.

But what are we "measuring" with GMST?

I leave that for anyone to answer; I think, as I've said before, this is the basis for much of the misunderstanding (and intentional misrepresentation) around climate change/global warming.

@zebra,

Well to the degree you accept the standard definition of climate, that it is the long term average of weather at a location, the global climate is that and the long term spatial average. On the temperature observable, then, the long term (global) spatial average is GMST. What's wrong with that? As most averages (drawn from distributions with finite energy, at at rate) it has a well-defined dispersion, even if that dispersion need not be symmetric. And, presumably, it has an empirical distribution.

Long term and spatial averages are never directly observable, any more than the mean state of a fair coin. That doesn't at all indicate that declaring there is a mean state of a fair coin is "misrepresenting" it.

By Jan Galkowski (not verified) on 10 Jun 2015 #permalink

In reply to by zebra (not verified)

Zebra: "So I will repeat: GMST is a proxy, not a measurement in the conventional sense."

Yes, GMST is a proxy, you are absolutely correct about that. But many measurements are also proxies, and that is the part I'm pretty darn sure you don't get.

" You cannot determine causally, from the value derived, any outcome for the system."

Not making a lot of sense there.

Brian, and in the same way, using a bimetal is not a proxy in the sense as rate of growth of specific cells in a tree found in a limited range of altitude and latitude.

Proxies: They are turtles, all the way down (or up).

Greg, my #27 should explain what I mean there.

Can you answer my question, and show how you would use the information to predict some outcome?

Zebra, the change in global surface temperature, which is a measurement, is known to change over time primarily because of CO2 increase in the atmosphere. This is known to be linked to a range of outcomes. If that is what you are questioning here, then you have a very steep hill to climb in making your argument.

You seem to be arguing that because it is theoretically possible for the surface temperature measurements for planet can have any one of a range of values, change over a range of values, or have a range of distributions, then relating global surface temperature to the problem of global warming on the Earth right now in 2015 is not possible or relevant. But this is wrong. Any planet that is earth like (in range of temperatures, overall composition of atmosphere, with abundant free water) will act this way.

#21 Jan,

You seem to be confusing mass density (3 gm/cc) with energy density, which would be in J/kg or J/L, where J is Joules.

As Greg says it is a bit off topic. But it does illustrate that the language is the physics though-- the first thing we have to learn is to use the right dimensions.

#15 Obstreporous Applesauce. You must be a very old-timer; we haven't used hydraulic analogy for teaching electrical circuits since before my student days. The main reason is that it's wrong, but also, and this is to the point: Why would we assume that fluid dynamics is easier to grasp than electricity?

@zebra,

#34, no I know perfectly well what the units should be. What I meant was that J/kg(H2O) is not that much different than J/kg(granite) whereas J/kg(air) is likely to be. And that's because kg/L of H2O is not that much differen than kg/L of granite.

Re #35 In #27 you wrote:
"I leave that for anyone to answer; I think, as I’ve said before, this is the basis for much of the misunderstanding (and intentional misrepresentation) around climate change/global warming."

So clearly you are having difficulty keeping track of what you wrote. Unless you are being deliberately obstreperous.

By Jan Galkowski (not verified) on 10 Jun 2015 #permalink

In reply to by zebra (not verified)

#31 Jan,

Sorry, I don't know what you mean by "misrepresenting"-- I never used the term.

Can you do what I asked Greg to do? Just take some value for GMST, and show me how you would use it to determine something?

I think fluid dynamics is easier to grasp at the simplest level than electricity because the average kid interested in electricity has already spent a life time playing around with water. So voltage/current/resistance can be made to make sense very quickly with reference to rate/speed/size of tube or opening for water.

As an analogy, I remind you, not as an identical system. Analogies we use to explain things are not identical to a system being explained, but rather, they share some properties but are otherwise easier to relate to or grasp. That is why we use them. If water went at near the speed of light and its speed did not change with restriction it would be strange and spooky and not a good analogy.

Having said that, once you get beyond that basic concept water is washed up as an analogy for electricity. Sometimes the differences between the analogy and the focal system do actually get in the way (as may be the case with water and ohm's law). Then, when we try to explain inductance with water we just get water spraying everywhere and the lawn gets watered but nothing else seems to work. Capacitance is a total mess as well. "I have two buckets of water and they are right next to each other" ... probably not.

#33 Alison,

Why don't you just answer the question? It isn't a trick question, it's just basic physics. Use physics language, not hand-wavy terms like "something is 'linked' to something".

Zebra, the premise of your question has been destroyed, why would I "answer" it?

Yes, I am an old timer. I am a very bad tempered old timer. There are a lot of things they don't teach these days that they should, like respect your elders, Zebra, and don't badger the adults.

But you are wrong. I just picked up a beginning electronics book written in the last 10 years and noted the electricity-water analogy in it. When this analogy is used, it is a brief and intuitive leg-up used early on to introduce an alien topic. It is not belabored or carried through as the material progresses. It is both useful and disposable, because most people don't have some sort of analogy deficit. Again, learn what an analogy is before spouting off. Wow.

And just to point out the flexibility of the analogy, I saw a variation of it used in an upper level hydrogeology class. It was a simple exercise to demonstrate how water flows through an area and to create a flow net by measuring electrical current at selected points on a small, pond-shaped metal plate connected to a battery. It was a cheap, fast and instructive exercise, and nobody drew weird conclusions from it or made more of it than what it was.

Analogies are figures that people from all walks of life commonly use to communicate. Learn what figurative speach is. And in particular, again, learn what an analogy is.

By Obstreperous A… (not verified) on 10 Jun 2015 #permalink

I'd like to add something from an anthropological/linguistic perspective as well. First, things like analogies and metaphors are all part of the same phenomenon even if they are sometimes defined as distinct in the language arts.

When we communicate with language, one could argue that everything is a metaphor. Everything. Every little thing. This argument comes in part by deconstructing boundaries between meaning from utterances that are metaphors and those that are not quite metaphors, then working down from there. A phrase with meaning ends up looking a lot like a metaphor if you do that, which requires a fair amount of reading and understanding theory (beyond what happens in a comment on a blog post) .

In parallel, something similar could be said of symbolic processing, but that is for another conversation at another time, probably.

You could say, I suppose, that a model is an analogy like a map is an analogy.

“Our earth is a globe whose surface we probe
no map can replace her but just try to trace her”
~Steve Waterman

Timely article. How to design a metaphor:
http://aeon.co/magazine/culture/how-to-design-a-metaphor/

By Obstreperous A… (not verified) on 10 Jun 2015 #permalink

The map is not the terrain, and the menu is not the meal....

"I have a map of the United States... Actual size. It says, 'Scale: 1 mile = 1 mile.' I spent last summer folding it."
-- Steven Wright

By Brainstorms (not verified) on 10 Jun 2015 #permalink

"Kiteo, his eyes closed."

",,, obviously, there could be a cold winter in Boston and warm in Alaska, or vice versa, with the same GMST."
If the GMST changes, the winters in Boston, Alaska, and all the other places where temperature is measured and from which the GMST is derived must change. Only if you ignore physics, is it theoreticlly possible for every measurement but one to be exactly the same.
Loading the weather dice by increasing the GMST doesn't just affect the probability of losing rolls(droughts/snakeeyes; floods/boxcars), it affects every single roll of of the dice.
It also adds new faces to the dice. California drought -> you just rolled a zero; Texas floods? welcome to the world where you can roll a 13. Gentle rainfall overnight, followed by 68F/20C partly cloudy perfect spring day? If it weren't for global warming, that wouldn't have happened either. If a butterfly can flap its wings and set in motion a chain of events leading to a hurricane, then the change in energy measured(proxie by a change in GMST has surely changed your local weather every instant of every day.
An increase in GMST will cause an increase in global mean absolute humidity. Clausius-Clapeyron allows estimation of the amount. Arrhenius noted in 1896 that the average relative humidity was ~60%, and surmised that the unchanging land/ocean ratio, and small changes in tropical-polar temperature difference would continue to maintain an approximately constant average relative humidity. Measurements have confirmed this.

By Brian Dodge (not verified) on 10 Jun 2015 #permalink

An hydraulic reactive element analogous to an inductor is a slug of water flowing in a pipe. Energy is stored in the magnetic field of an inductor, and the kinetic energy of the water flowing in a pipe. if the flow is interrupted, by closing a valve in the pipe or opening a switch in series with the inductor, the pressure across the valve, or the voltage across the switch rapidly rise. if there is a standpipe connected via a one way valve, or a capacitor connected via a diode, the pressure(voltage) will rise as the energy stored in the flowing slug of water(inductor magnetic field) is transferred to the pressure head of water rising in the pipe(voltage on the capacitor.) Mongolfier invented an automatic hydraulic ram pump in 1796 & it was patented in 1797; Siegfried Marcus was issued a patent in 1883 for a "magneto-electric ignition system."
Water sloshing back and forth in a bath tub or the Pacific Ocean, electrons sloshing back and forth in an L-C circuit, a spring balance wheel in a mechanical watch, a pendulum in a grandfather clock, or the oscillations of a cesium 133 atom all can be described by the same harmonic equations (but see http://adsabs.harvard.edu/full/1957SvA.....1..637Fhttp://adsabs.harvard… for a discussion of some of the devilish details)

By Brian Dodge (not verified) on 10 Jun 2015 #permalink

Brian Dodge, #45

Congratulations. You have demonstrated that you actually care enough about climate change to put your ego aside and take a chance on being wrong.

You got the first part right:

"the change in energy measured(proxie by a change in GMST"

Yes, that's the only variable for which GMST is an (imprecise) proxy; it is pretty much qualitative-- over the long term, it must rise, according to the physics of greenhouse gases, until a new equilibrium state is reached. But that's all it is; it validates the initial premise, which is that there is no (hidden) mechanism that transports energy out of the climate system.

Why does zebra fume and rant and make such a big deal about this?

Because every time you engage in the [pause/no pause/explain the pause] game, it elevates the Denialist claim, which is implied but often not openly articulated, that there is such a countervailing mechanism.

I've been following this a long time now, and we are way past the point where this should remain an open question-- it is the "settled science". Why are we still letting these people frame the discussion as if it's twenty or more years ago? Seriously, it's like some kind of co-dependence.

Brian, I will post another comment on some of the details that I think are not quite correct, but real life is calling right now.

Brian,

The remainder of what you say continues the error of thinking of GMST as a "cause".

Will an increase "cause" humidity to rise? No, because as with the temperatures that can be hot in Alaska and cold in Boston or vice versa, we can have higher air temperatures above the desert/ocean and colder over the ocean/desert. Same GMST, different humidity, or different GMST, same humidity.

How then can we say it is a "cause"?

Now, will the humidity rise? Of course. But that will be caused by local increases in energy, acting on the local system. In some cases, increased evaporation could precede increase in air temperature. Think about the arctic summer, when the temperature is very constrained but the ice is crazy melting.

Why is it important to maintain such strong discipline with the language? Again, because people are easily misled-- oversimplification and analogizing are the tools of the propagandist. At this point, I bet most people think that "trying to stay below 2C" means everything will be fine until we get to that temperature. Only then will the ice sheets crash, crops fail, and so on. Because GMST will be the "cause". Arrgh.

I will refrain from talking about the electricity stuff unless you really want to defend it. I've had to un-teach people who picked up various misconceptions from those kinds of analogies, and it is far more work than trusting them to understand correctly in the first place.

So at long last the lemmings begin to recognize the edge of the precipice approaches. Still a couple of missing factors;: we have passed the '400' now comes the effects of Oceanic Acidification! Suck it up fools

By John Alldis (not verified) on 13 Jun 2015 #permalink