September 24, 2003

Stupid Conservative Myth #5

Global warming is in the news. Even yesterday, a big glacier showed further signs of melting in the arctic, which is widely seen as a symptom of global warming (to be fair, it could be a local "weather" effect rather than a climatic indicator, but that's not how it is reported). So it's time to talk about another myth held by know-nothing conservatives. These may seem silly on the surface, but these statements that would ordinarily make no common sense are instead common knowledge in the world of Faux news, talk radio and conservative blogs and message boards. This one is one of my favorites:

Liberals believe that global temperatures are less affected by cyclical, documented changes in the earth's climate, and more affected by yuppies driving SUVs.

Well, there are three parts to this one. First, can we document changes in greenhouse gases (such as Carbon Dioxide, hereafter CO2), and can we show that humans are responsible for those changes? Second, can we show that global temperatures are indeed rising, and how does this look in a historical (geological timescale) context? Finally, can we show that increases in greenhouse gases are affecting global temperatures?

Of course, some nutballs don't even think the greenhouse effect is real, so maybe I should start there. Greenhouse gases are gases that absorb infrared radiation effectively. Because incoming sunlight is mostly in the visible band of the spectrum, it isn't blocked (much), so it warms the Earth. Outgoing "Earthshine" is mostly in the infrared, so the gases tend to block this and warm us up by about 60 degrees Fahrenheit (33 C). We know the amount of the warming because we have a "control" nearby (Earth's Moon) which is at the same distance to the Sun, basically, but with no atmosphere, and the average temperature of the Moon's surface is 60 degrees F cooler than Earth. Ok? So the greenhouse effect is real. In fact, without it, the planet wouldn't be habitable.

Charles Keeling did the primary work on beginning to measure levels of atmospheric CO2. He put detectors all over the world, and his measurements became the famous Keeling curve:

The wiggles in the curve are due to the photosynthesis cycle in the northern hemisphere (which has more vegetation and so affects the CO2 level worldwide, even in the southern hemisphere, because the atmosphere mixes so effectively). The general rise is due to ... what? Well, there are some who believe that volcanism and other natural sources (such as geysers, thermal vents, etc) are affecting the CO2 levels in the atmosphere more than humans (represented above by yuppies in their SUV's ... in reality, cars only represent about 1/3 of our total emissions).

There's an easy way to check this, described in more detail in this FAQ. Carbon comes in three isotopes. Normal Carbon (C-12) is the most abundant, but you also have a little bit of C-13 and C-14 (Carbon with 1 or 2 extra neutrons in the nucleus). C-14 is, in fact, used in radioactive dating for organisms that have died within the past 100k years or so, but that's another story. It turns out that "natural" C-12 emissions tend to have some C-14, because they represent carbon reservoirs that were in the atmosphere more recently. Fossil fuel reservoirs have essentially zero C-14 because they've been buried so long that all the C-14 has decayed away (half-life is 5700 years) without being replenished from the atmospheric carbon (which itself has its C-14 replenished by cosmic ray interactions in the upper atmosphere).

Ok, I realize I just lost all the conservatives, but the rest of you bear with me. The summary is: Fossil fuels and natural sources of Carbon have different "isotope fingerprints". As Carbon has increased in our atmosphere in the past 200 years, the isotope fingerprint of the Carbon has changed to more closely reflect that of fossil fuel reservoirs. This shows that the majority of the increase has been due to human activity. So that's the first part. Sorry, yuppies, but your SUV's are, indeed, causing much larger changes than any natural process. At least on a decadal timescale.

How does the Carbon in the atmosphere today compare to the geologically recent past?

During the past 450k years, the Carbon level has never been as high as it is today. How do we know Carbon abundances from long ago? In the recent past, tree rings and other natural indicators can give us some indication, but most of our information comes from ice cores. Each year, new snowfall leaves a new layer of ice on top of glaciers. This ice has air bubbles trapped, relics of the ancient atmosphere. By drilling into the ice and getting ice cores from glaciers, we can look at the properties of our atmosphere from long ago. You can also estimate temperature by looking at Oxygen isotope ratios (why they're related is complex but generally accepted) or what kinds of organisms were dominant at the time.

So the Carbon abundance is unprecedented for the last 450k years, but what about further back? It is clear from other indicators that Carbon abundances were *much* higher in the past. That's because of the Faint Sun Paradox, which is a long story for another time. Basically, though, the Sun was about 30% fainter long ago, but Earth's temperatures were similar to today, and the reason for the balance is the increased amount of CO2 back then. So over the very long haul (billions of years), natural sources *have* had a much greater effect that what we are currently doing. However, we are changing the composition of the atmosphere much more rapidly than it has ever been changed before.

What about temperatures? Are they rising as well? And is this linked to Carbon abundances? Again, viewed over the past 160k years, the data is pretty convincing:

This graph leaves off the past 15 years, during which average global temperatures have risen by about 0.6 degrees Centigrade, making current temperatures unprecedented in recent geological history. I also detect a strong correlation here between Carbon levels (blue) and Temperature levels (red). This is the kind of stuff Buscho recently tried to suppress.

When you talk about temperatures rising, you have to be careful not to confuse "weather" (e.g. Canada had a hot July) with "climate". Weather means short term localized variations (like the famous of example of Greenhouse supposedly being warm enough 1000 years ago for Viking settlements) with global average temperatures, which better indicate trends. So we have a good understanding of what temperature is doing now and in the geologically recent past. But what about the future?

That's tricky. We know that Carbon abundances in our atmosphere will roughly triple (at least) by 2100 (that's from simple math, looking at the rate of energy usage and emissions vs the total CO2 in the atmosphere). How will this affect temperatures? Will they continue to track CO2 as in the past? Here is a graph showing a variety of generally accepted and scrutinized models:

How much the temperature will change depends on feedbacks. Positive feedback, for example, occurs when increased Carbon warms the atmosphere, which prompts more evaporation. Since water vapor (in the form of high thin clouds) is a major greenhouse gas, that can warm the Earth still further. Another example would be warming temperatures causing more ice to melt, which exposes a darker surface. Since the Earth's surface would be better at absorbing light energy, that would warm us up.

Negative feedback would be if the increased temps cause more water vapor in the form of low, thick clouds, which would tend to cool us off (blocking visible light instead of mainly infrared). Some claim that increased Carbon will result in accelerated plant growth (the "CO2 is plant food" argument), which will soak up the excess and be a negative feedback to the system. But there's no way the biomass can soak up *that* much CO2 (even faster growing plants eventually decay on timescales of decades, releasing their sequestered Carbon), so that doesn't really work.

We honestly have no idea how much positive/negative feedback we'll see over the next 100 years, hence the wide range (in degrees C) in the models. If the change is only a degree or so, that's no big deal. If it is 3+ degrees, that can change the models an awful lot and cause feedbacks to become very unpredictable. does the conservative myth stack up? Well, we *do* currently affect the Carbon in the atmosphere at a faster rate and in greater quantities than any natural process. Carbon has been higher in the past due to natural processes, but for the very distant past, the Sun was fainter which made more greenhouse gases a good thing. So the status of the myth is somewhat mixed, if you look at it in detail (which is impossible for conservatives who wouldn't read to this point anyway). On the very long term (billions of years), Carbon has been higher in the past, but humans are affecting the totals on a timescale of decades, not billions of years.

This leads us to item #5 that you must believe in order to be a good conservative:

The only good science is science that agrees with conservative, corporate governing philosophy. Evolution, global warming and the big bang theory are all ideas dreamed up by godless big government liberals to put in their crazy textbooks and poison the minds of our children.

The important question now is: How should we respond to the increasing CO2 and increasing temperatures? Is anything being done? This is long enough, so I'll talk about that tomorrow. By the way, an excellent video on this whole topic is called, "What's Up With the Weather?", and it has a pretty cool website associated with it.

Posted by Observer at September 24, 2003 07:10 AM

Comments on entries can only be made in pop-up windows while those entries are still on the main index page. Sorry for the inconvenience this causes, but this blocks about 99.99% of the spam the blog receives.

Thank you for your enlightened and very interesting post.

Since I doubt that Doc or any of his ilk have the parts to argue with you on this, I have a question:

I have heard about "holes" in the ozone layer affecting global warming: Is this true and how does it interact/affect the carbon greenhouse gas circumstance you describe?

If this is too large of an issue, don't worry about it. Just wondering.

Posted by: TheLiberal on September 24, 2003 07:43 AM

To the best of my knowledge, ozone depletion and the greenhouse effect are not directly related. In the sense of global temps, ozone does absorb UV light, which means it tends to cool us off, but I don't have a handle on the order of magnitude of the temperature effect of that absorption.

The ozone hole was an easier problem to solve than the greenhouse effect because we had ready alternatives to ozone-destroying CFC's and the economic cost of switching was minimal (the same corporations manufacture all the refrigerants, so for them to switch from one to another was no big deal). We don't have a ready alternative to CO2 emissions, so it is a much nastier problem.

Posted by: Observer on September 24, 2003 07:56 AM

Probably one of the most readable explanations of Global Warming I've ever come across. Very well done.

Posted by: Bav on September 24, 2003 08:09 AM

Well done, Observer. Of course, you already know that publishing clear explanations of scientific results is a terrorist act, and the Throught Police (or whatever Ashcroft's crew is calling themselves this morning) will be collecting you shortly.

Actually, I had the opportunity a few years ago to talk with one of the honchos in studying atmospheric chemistry (he was where I was, he and I were about the only spectroscopists on campus, and he'd done some astrophysics early in his career). The ozone hole is very interesting but it isn't clear what it means. There is very little long-term data on that (not even as much as Keeling's original curve, and high-altitude ozone doesn't get directly locked into fossils or in ice cores, so you need to find a proxy for it, and that isn't easy to do with confidence), so we don't have much handle on what the long term state should be, absent anthropogenic trends.

The really scary stuff comes when discussing the vertical convection patterns in the ocean, and whether that circulation is in danger of halting. That has drastic effects on climate, since the heat budget in water is ridiculously larger than that in the atmosphere.

Posted by: Feff on September 24, 2003 09:26 AM

True enough about the oceans. They may turn out to be a relatively short-term climate changer as well, in a dramatic way (not sure if they'll be as fast as our effects). It is also not clear that we influence ocean convection with our mucking with the atmosphere.

The bottom line for me is that it is a system filled with nasty uncertainties. Lots of knobs and dials on a big box, and we don't know what they all do. We're taking the CO2 dial and cranking it all the way to "MAX" instead of looking for alternatives and pouring money into research. If I were president, I'd put a billion dollars or more into a research program to make fusion power plants a reality.

More on that next post.

Posted by: Observer on September 24, 2003 09:42 AM

Dangit. I read a scientific paper one of the grad students here forwarded to me a while back, and it had *something* in it that suggested strongly that some previously overlooked effect might very well take care of global warming (be a strong negative feedback effect) but heck if I can remember the details or find a reference to it. Bah! I'll see if she remembers when she gets back from Germany.

As for SUVs, I don't drive an SUV, but I do own a full size pickup, but I still take offense to that comment. I'm sorry, but it just doesn't fucking matter what milage vehicle you choose to drive. What matters is how much fuel you burn (aka how much carbon you return to the atmosphere). If I bought a Canyonero that got two miles per gallon, but only drive 150 miles a year, that's my choice, and I'm only contributing 75 gallons worth of carbon. Someone driving a nice hybrid Prius getting 50mpg, but who's daily commute is 100 miles round-trip, they're contributing 400 gallons a year worth of carbon, and they can just get the hell off their high horse.

Thus speaks the bicycle commuter.

The problem with the ozone hole is allowing ultraviolet light to cause skin cancers. Not a big climate effect, just bad for humanity on another level.

Posted by: Humbaba on September 24, 2003 10:11 AM

I've heard, in brief blurbs in Geology and Astronomy, mostly in Geology, that "no one really knows."

But I'd like fusion power.

Posted by: Polerand on September 24, 2003 10:55 AM

The big feedback that atmospheric scientists can't model is the ocean currents. None of the models shown in that last graphic include anything about the oceans, I don't think.

The "yuppies driving SUV's" is not my wording, but I take it to represent humanity's contribution to global warming. I don't take it as a given that people with SUV's are all problems. Hummers, maybe, but not SUV's. :) I agree that it all depends on how much fuel you burn, not so much the rate at which you burn. Someone who chooses to live 50 miles from work can definitely be a bigger emitter with a fuel-efficient car than a guy with a Suburban living 1 mile from work.

You know the difference between Hummers and porcupines? With a porcupine, the pricks are on the outside.

Posted by: Observer on September 24, 2003 01:00 PM

A Hummer is an SUV. HumVs are loads of fun to drive, I can only imagine the civilian version is just as much fun or more.

Posted by: Humbaba on September 24, 2003 01:46 PM

Yer absolutely right about it being the amount of fuel burned that does it, Humbaba ... but choice of vehicle *does* make a difference, too. If the guy with the 140 mi/year and the guy with the 100 mi/day both drive hybrids, their combined emissions will be considerably lower than if they both drive SUV's ... the guy cycling his commute, on the other hand rocks!

Nice post, Observer.

Posted by: Dandelion on September 24, 2003 03:41 PM

You're a smart guy, Hummer. (Not to be confused with Hummerô). I'm sure you can figure out that Observer is referring to the average American (over-)consumer, not a conscientious guy like you who is more often emitting a li'l sweat and just plain ol' CO2 from your lungs than emitting those nasty gasses from your truck. You're a closet enviro-liberal! I just knew it! :-D

Posted by: Perkusi on September 24, 2003 05:07 PM

Excellent readable summary, Observer.

Thank you.

I think the oceans are tremendously important in climate. Doesn't the shifting temps and circulation of the El Nino/La Nina cycle alter climate pretty dramatically? Weather at the very least. But I suspect it demonstrates more.

In the Monterey Bay during the 97-98 El Nino season, the primary productivity -- photosynthesizing plankton -- was dramatically altered (with big effects on the food chain. ) Given the huge role plankton play in sequestering carbon such circulation shifts could have tremendous impact, I'd imagine.

There are some researchers on the central coast of california who've been doing experiments in the southern ocean -- SOFEX II was the most recent, I think. Vast reaches down there don't have much in the way of plankton production... so they have been trying to seed the ocean with iron. And in their experiments, the plankton blooms like crazy. They then measure the carbon uptake from the atmosphere. Results have been mixed.. they have demonstrated carbon uptake, but where it goes from there is unknown. It very well could simply seep back into the atmosphere. And of course, ecological impacts are unknown as well. ( the research started out as an investigation of whether iron was the limiting nutrient down there...)

Unfortunately, there's a lot of immediate interest in iron fertilization with talk of "carbon credits..." industries could seed iron to trade what they spew. Until more is known, it doesn't seem like a good idea to me. Not only don't we know if it would work, we don't know what we'd do to the ecosystem or what the long term climate effects would be.

Anyway, I look forward to your next post.

Posted by: Just Mary on September 25, 2003 05:45 AM

What's this I hear about the differences between surface temperatures and atmospheric temperatures? That there's evidence of one rising but not the other, or something like that. Supposedly a serious hole in our understanding of global warming.

Posted by: Rupert on February 24, 2004 02:00 PM

Give me a citation on what you're talking about, and I'll tell ya what I think. The big picture, as has been expressed in my original post and comments, is that there are a *lot* of holes in our understanding of global warming (all the positive and negative feedbacks ... cloud behavior, oceans, etc).

When you don't understand a complex system, it's ok to go ahead and crank one of the knobs (in this case, CO2) over to "max" and see what happens. Provided it is a video game you can reset. When it is the Earth, I think a little bit of caution is appropriate.

But hey, that's just me, Mr. Histrionics.

Posted by: Observer on February 24, 2004 04:01 PM

I'm a liberal, and here's where you're wrong. George W Bush funded a study to see if global warming existed, and he found that it does in fact exist (our president said that). There are less than reputable minority of scientists who still believe humans have no impact on global warning. VERY small minority. Not a myth, maybe some research would help?

Posted by: Kevin Andrew Beal on December 16, 2005 08:50 PM

Just because the president makes a statement does not make it a fact ("We do not torture."), certainly not in the eyes of the wingnutosphere. Read the statement about liberals' beliefs again and try to tell me most Republicans disagree with that. What exactly am I supposed to research here? I don't understand.

Posted by: Observer on December 16, 2005 09:29 PM

Whatever side of your arguement is on, you must get your facts straight. I did not have to read far into your website before I came upon this statement," Because incoming sunlight is mostly in the visible band of the spectrum..."
By definition, ALL sunlight is in the visible band of the spectrum; that is why it is called sunLIGHT. Now if you are refering to the entire spectrum which we receive from the sun, only a small portion is in the visible form. See any NASA site ...for example

Posted by: Bill on April 3, 2006 05:20 AM

Errr, what definition of "light" are you using? My definition, shared by the scientific community, is "electromagnetic radiation", and it is by no means limited to the visible band of the spectrum.

Posted by: Observer on April 3, 2006 08:37 AM