How to demonstrate the human impact on the environment?
September 29, 2005 3:16 PM   Subscribe

Is there a simple proof to demonstrate the human impact on global climate change? A common argument made by American conservatives is that humans can't possibly have a great enough impact to make a difference. Surely there's some relatively simple bit of logic that can prove our impact. Perhaps something along the lines of: "Global emissions of greenhouse gases amount of X billion tons each year, or Y trillion in the past century. Every Z billion tons of greenhouse gases increase the earth's radiative forcing by A%, each percent of which warms the earth by B degrees."
posted by waldo to Science & Nature (27 answers total)
Not that I don't believe that we humans are contributing to global warming BUT... The environment is extremely complicated as well as works in numerous dynamic cycles that we don't at all understand. We've only really been keeping good data on the climate for the last 50 years or so and just simply don't have the data or understanding to do what you're suggesting.

The state of the earth is so dynamic that there is no natural state of where things should be, how hot it should be, how humid, how much light gets to the surface, how much ice, how many living things there are, etc. Since it is always changing, regardless of any human activity, trying to stop it or slow it, or trying to show how much we are adding to it is just too much to ask.
posted by pwb503 at 3:22 PM on September 29, 2005

"Global emissions of greenhouse gases amount of X billion tons each year, or Y trillion in the past century. Every Z billion tons of greenhouse gases increase the earth's radiative forcing by A%, each percent of which warms the earth by B degrees."

Well, in general A is not known spesificaly. However, about 14% of the CO2 in the atmosphere is the result of human production. 14% is a pretty large number, so to say that humans have no effect on the environmen is silly.

There is no rational basis to assume that humans can't have an effect.
posted by delmoi at 3:40 PM on September 29, 2005

Ask them if a 14% increase in their pay would 'have no effect'.
posted by delmoi at 3:41 PM on September 29, 2005

Hey we were just talking about this at my house a few days ago! Here are some links [and a discussion by my boyfriend] about human influence over global warming, replete with facts from the Pew Center and the EPA. People generally say "Yes the earth has hotter and cooler years/decades/centuries" but I think this is more like people saying "We are, with the things we do, in the US, every day, accelerating the pace at which the Earth is warming."
posted by jessamyn at 3:48 PM on September 29, 2005

Response by poster: Ideally, I'd like for the proof to be completely transparent. That is, the math should be self-contained, so that doubters could do the math themselves, scratch their head, and say "gosh, the math is right, the the numbers you used are hard to argue with."

I should mention that I'm about as familiar with the environmental sciences as a layman could be. I just finished my second read of James Speth's "Red Sky at Morning," which is thick with statistics on the topic. I'm just not smart enough to cobble the data together into a meaningful math-based assertion.
posted by waldo at 3:55 PM on September 29, 2005

Have any researchers managed to get better correlation between the CO2 level and the global temperature? Better than "they both increased since 1958 when we started measuring these things". Something like a spike in one leading to a spike in the other, that would actually reinforce that it's causation.
posted by smackfu at 4:09 PM on September 29, 2005

I'd show people this graph, which measures CO2 concentrations in the atmosphere since 1958. The CO2 in the atmosphere acts like a greenhouse, trapping heat. I'm afraid I don't know enough about radiative forcings to know if there's a simple equation summarizing the greenhouse effect.

According to Wikipedia, the concentration of CO2 in the atmosphere has increased 40% since the start of the Industrial Revolution; it hasn't been above 300 ppm in the last 10,000 years; volcanic activity releases about 1/100 of the CO2 released by human activities.

According to Elizabeth Kolbert's article The Climate of Man - I in the New Yorker:

Antarctic ice cores also show that carbon-dioxide levels today are significantly higher than they have been at any other point in the last four hundred and twenty thousand years.
posted by russilwvong at 5:10 PM on September 29, 2005

smackfu: Have any researchers managed to get better correlation between the CO2 level and the global temperature? Better than "they both increased since 1958 when we started measuring these things". Something like a spike in one leading to a spike in the other, that would actually reinforce that it's causation.

The fact that CO2 traps heat (the "greenhouse effect") is uncontroversial. See Kolbert's description of the findings of John Tyndall in 1859.

... To use Tyndall’s Victorian language, if the heat-trapping gases were removed from the air for a single night “the warmth of our fields and gardens would pour itself unrequited into space, and the sun would rise upon an island held fast in the iron grip of frost.”

Greenhouse gases alter the situation because of their peculiar absorptive properties. The sun’s radiation arrives mostly in the form of visible light, which greenhouse gases allow to pass freely. The earth’s radiation, meanwhile, is emitted mostly in the infrared part of the spectrum. Greenhouse gases absorb infrared radiation and then reëmit it—some out toward space and some back toward earth. This process of absorption and reëmission has the effect of limiting the outward flow of energy; as a result, the earth’s surface and lower atmosphere have to be that much warmer before the planet can radiate out the necessary two hundred and thirty-five watts per square metre. The presence of greenhouse gases is what largely accounts for the fact that the average global temperature, instead of zero, is actually a far more comfortable fifty-seven degrees.

posted by russilwvong at 5:11 PM on September 29, 2005

"humans can't possibly have a great enough impact to make a difference"

The problem is not so much proof as it is rhetoric. "Make a difference", "significant effects", or "changes that directly affect me" do not have a logical negation.

Even if you could prove significance, how do you answer the question, "So what?"
posted by mischief at 5:34 PM on September 29, 2005

I personally welcome human-induced climate change, and look forward to the technological solutions that we will develop. So even if you could prove something, I wouldn't care.

Robots are the trees of the future, as they say.
posted by trevyn at 5:48 PM on September 29, 2005

Response by poster: Even if you could prove significance, how do you answer the question, "So what?"

One thing at a time here, mischief. I'm looking to combat ignorance, not willful morons. :)
posted by waldo at 6:12 PM on September 29, 2005

mischief: Even if you could prove significance, how do you answer the question, "So what?"

So we need to stabilize the amount of CO2 in the atmosphere, by limiting the total amount of CO2 that everyone puts into the atmosphere each year. Under the Kyoto agreement, the industrialized countries--except for the US and Australia--agreed to limit their CO2 emissions. The major countries which have not yet agreed to limit their emissions are the US (responsible for roughly 25% of global CO2 emissions in 2002), China (15%), and India (5%).
posted by russilwvong at 6:31 PM on September 29, 2005

The CO2 graph is a fine choice.

Better though, is the simple argument: let's suppose that there are cyclical changes going on that are warming the planet, in addition to what Man is doing. If true, the response is not to throw up your hands and say, "Oh well, can't fight nature" - the response is to redouble our efforts to change our ways, because now it's not just us, it's a planetary cycle too that we have to counteract!

Let's say you're in a room filling with water. And let's suppose that there are two faucets filling it, one under your control, and one not. (This is the conservative argument... that global warming isn't caused by us.) But wouldn't this situation make you turn off your faucet as fast as you could? If global warming is caused only by Man, you could always say, "Well, we'll wait until the water is up to our chin, then turn it off." But if there's another faucet you can't turn off... you would shut off yours ASAP.

So in other words the standard conservative argument is nonsensical. But you probably knew that. The only people trying to make the argument that global warming isn't a problem are paid by fossil fuel industries.
posted by jellicle at 6:44 PM on September 29, 2005

Even if you could prove significance, how do you answer the question, "So what?"
posted by mischief at 5:34 PM PST on September 29 [!]

Well, for one thing, by employing carbon sequestration technologies that store carbon in an inert, non-atmospheric form — like trees or by deep-sea injection.

Theoretically we would start by storing away as much carbon mass as we measureably place into the atmosphere in the form of CO2, through our day-to-day activities.

Then we can begin to examine the question of how much CO2 is released or generated by natural processes, and how to counteract that effect.

Just from a general engineering point of view, I imagine it would be easier to study and control the extremes of weather, were we able to remove ourselves from the causality side of the equation.
posted by Rothko at 6:47 PM on September 29, 2005

"I'm looking to combat ignorance, not willful morons."

The willful morons are the ones in control.
posted by mischief at 7:10 PM on September 29, 2005

An environmental auditor showed a similar CO2 graph, but it had a bit of a sting in the tail. It went a bit like this:

"There seems to be a strong correlation between CO2 levels and temperature," he said, and put up a graph that looked like a heart attack. Up and down, peaks and troughs, but sure enough, the lines for temperature and CO2 levels were pretty much entirely in step.

"All that shows is that CO2 levels go up and down all the time!" said the SUV driver in the audience.

"Well, that's true," said the auditor. "The scale on this graph is a little exaggerated, though. Here it is over 40,000 years." Voila, a nearly flat line.

"So there's been no real change in climate at all!" quips Mr Humvee.

"Well," says the auditor, "the graph only goes up to the Industrial revolution. Here's the rest of it, up to the present day." He overlays two lines that skyrocket to a level never, even seen in the history of mankind, commencing shortly after the industrial revolution and screaming ever upward throughout the 20th century. One is temperature. The other is CO2. They align perfectly. The awed silence was deafening.

He also showed some photos of the icecap on Kilamanjaro over the last ten years, and a map of ice coverage in Antarctica and the Arctic. The whole lot will be fucking gone in 40 years.
posted by obiwanwasabi at 8:01 PM on September 29, 2005 [1 favorite]

obisanwasabi, that sounds like an awesome presentation.

b1tr0t: what percentage of gasses are due to human action vs. natural effect?

That's pretty well known. Here's a RealClimate post on this subject: How do we know that recent CO2 increases are due to human activities?

Over the last 150 years, carbon dioxide (CO2) concentrations have risen from 280 to nearly 380 parts per million (ppm). The fact that this is due virtually entirely to human activities is so well established that one rarely sees it questioned. Yet it is quite reasonable to ask how we know this. ...

Another, quite independent way that we know that fossil fuel burning and land clearing specifically are responsible for the increase in CO2 in the last 150 years is through the measurement of carbon isotopes. Isotopes are simply different atoms with the same chemical behavior (isotope means “same type”) but with different masses. Carbon is composed of three different isotopes, 14C, 13C and 12C. 12C is the most common. 13C is about 1% of the total. 14C accounts for only about 1 in 1 trillion carbon atoms.

CO2 produced from burning fossil fuels or burning forests has quite a different isotopic composition from CO2 in the atmosphere. This is because plants have a preference for the lighter isotopes (12C vs. 13C); thus they have lower 13C/12C ratios. Since fossil fuels are ultimately derived from ancient plants, plants and fossil fuels all have roughly the same 13C/12C ratio – about 2% lower than that of the atmosphere. As CO2 from these materials is released into, and mixes with, the atmosphere, the average 13C/12C ratio of the atmosphere decreases.

Isotope geochemists have developed time series of variations in the 14C and 13C concentrations of atmospheric CO2. One of the methods used is to measure the 13C/12C in tree rings, and use this to infer those same ratios in atmospheric CO2. ...

And here's a graph from the Department of Energy.

posted by russilwvong at 9:36 PM on September 29, 2005

CO2 emissions from vehicles are not affected much by emission control equipment, which mainly acts to limit emissions of unburnt hydrocarbons, CO (carbon monoxide) and oxides of nitrogen. The first two of these tend to oxidize into CO2 in the atmosphere anyway.

You can't see CO2; adding it to air leaves the air looking clean. Clean-air regulations act to stop the air being made visibly dirty by emission of particulates (science talk for "smoke") and/or the creation of photochemical smog, the brown haze resulting from emissions of oxides of nitrogen.

Until geosequestration (i.e. capturing CO2 at the point of creation and burying it deep underground) becomes common, the amount of CO2 a country pushes into the atmosphere is going to be directly proportional to the amount of fossil fuel that country consumes; and the US currently consumes far more fossil fuel than any other country.

More here.
posted by flabdablet at 7:06 AM on September 30, 2005

I just returned a book to the library yesterday called Taken By Storm, which does a pretty good job arguing that climate change may or may not be caused by humans, that scientists who say it is certainly caused by humans are exaggerating and similar things. I don't like the way they made their argument, through vilification and other tactics they then accuse the "environmental lobby" of using, but their arguments are strong and otherwise well presented. Anything you work with should take their arguments into account.

You should also factor in natural climate change, where in written history there have been much warmer and much cooler periods than now, which do not necessarily seem to corelate to CO2 levels (e.g. vineyards in Britain and Greenland, cattle ranches on Greenland by Vikings (sorry, in a rush and no link), Alps maybe had no glaciers when Hannibal made his trek).

I'm not denying the validity of anthrogenic global warming, but these are tough points to argue against, and you should be prepared to respond to them, in addition to making a strong and clear case yourself.
posted by ykjay at 8:39 AM on September 30, 2005

b1tr0t: IIRC, Kyoto specificaly excludes these developing nations, but demands cuts from already developed nations like the US and UK.

That's correct. Kyoto was an agreement between the industrialized countries, which were responsible for about two-thirds of annual CO2 emissions in 1990. The US and Australia have withdrawn from the treaty, so no limits apply to them. All other industrialized countries have agreed to limit their CO2 emissions.

what is the CO_2 contribution of the US compared with nations like China

See above. The three major countries which have not yet agreed to limit their emissions are the US (responsible for roughly 25% of global CO2 emissions in 2002), China (15%), and India (5%).

I've based these figures on data from the Oak Ridge National Laboratory's Carbon Dioxide Information Analysis Center.
posted by russilwvong at 10:38 AM on September 30, 2005

ykjay: these are tough points to argue against, and you should be prepared to respond to them--

I think that's why it's useful to just present the CO2 measurements, and to note that CO2 traps heat. The CO2 measurements are uncontroversial. The CO2 greenhouse effect is uncontroversial.

Essex and McKitrick (the authors of Taken by Storm) can take potshots at environmental doomsayers, and come up with bogus measurements of average temperature, but they can't argue that CO2 isn't increasing, and they can't argue that there is no greenhouse effect.
posted by russilwvong at 11:07 AM on September 30, 2005

It's funny how often those scientists who take the view that there's not much to global warming turn out not to be climatologists (Ross McKitrick, coauthor of Taken by Storm, is an economist; Bjorn Lomborg, author of The Skeptical Environmentalist, is a professor of political science).

Everybody is of course entitled to their own opinion, but it seems to me that the opinions of people who actually work in this field are probably closer to reality than the opinions of those who don't.
posted by flabdablet at 11:17 AM on September 30, 2005

Ad hominem! Special interests! Chicken Little! Remember that global cooling scare? Argument by authority! Galileo, Galileo, Galileo!
posted by russilwvong at 11:19 AM on September 30, 2005

An ad hominem is not necessarily fallacious; if those making an argument lack knowledge of the subject matter, their arguments really are less likely to be correct than those who can reasonably be expected to be better informed.

Special interests: climate researchers would still have jobs, even if the global climate were doing something entirely different from what they have found it actually is doing. You might as well argue that physicists are all engaged in a desperate quest to keep their jobs by systematically falsifying the true charge of the electron.

Chicken Little published no peer-reviewed papers, as far as I know.

Which global cooling scare was that, again? I remember findings about variable solar output, and I remember reading of a short term cooling trend after the eruption of Mt Pinatubo, but I don't remember any serious research revealing human-caused global cooling. Links please?

I'm not arguing by authority so much as for a reasonable choice of authority, for those who have neither the time nor inclination to do their own original research. I'm suggesting that there are good and valid reasons why some people's opinions are likely to be better-informed than others.

If I recall correctly, Galileo was a guy who looked through a telescope and formed an opinion based on what he actually observed, as opposed to going with what was politically fashionable at the time. Doesn't that put him more in the climatologists' camp than that of the business-as-usual naysayers?

Seems to me that what we're looking at here is in fact Galileo and Galileo and Galileo... being studiously ignored by those in power, who prefer the soothing songs of their own tame economic theologians.
posted by flabdablet at 12:16 PM on September 30, 2005

Sorry, I was trying to be funny. Won't do it again....

I've spent an awful lot of time arguing with global warming skeptics over the Internet, and I was mocking the kind of knee-jerk responses that they come up with. IMHO, they're all bogus, often verging on conspiracy theory.

It is true that in the 1970s, researchers were worried about global cooling. For a discussion, see Spencer Weart.

In January 1961, on a snowy and unusually cold day in New York City, J. Murray Mitchell, Jr. of the U.S. Weather Bureau's Office of Climatology told a meeting of meteorologists that the world's temperature was falling. This was the first time anyone had worked through all the exacting calculations, working out average temperatures for most of the globe, to produce plausible results. Global temperatures had indeed risen until about 1940, Mitchell said, but since then, temperatures had been falling. There was so much random variation from place to place and from year to year that the reversal to cooling had only now become visible.(14*)

Acknowledging that the increasing amount of CO2 in the atmosphere should give a tendency for warming, Mitchell tentatively suggested that the reversal might be partly caused by smoke from volcanic eruptions and perhaps cyclical changes in the Sun. But "such theories appear to be insufficient to account for the recent cooling," and he could only conclude that the downturn was "a curious enigma." He suspected the cooling might be part of a natural "rhythm," a cycle lasting 80 years or so.(15) The veteran science correspondent Walter Sullivan was at the meeting, and he reported in the New York Times (January 25 and 30, 1961) that after days of discussion the meteorologists generally agreed on the existence of the cooling trend, but could not agree on a cause for this or any other climate change. "Many schools of thought were represented... and, while the debate remained good-humored, there was energetic dueling with scientific facts." The confused state of climate science was a public embarrassment.

posted by russilwvong at 1:04 PM on September 30, 2005

Here's on the supposed global cooling scare.
posted by russilwvong at 2:42 PM on September 30, 2005

A personal carbon footprint calculator from the chaps at The CarbonNeutral Company, who used to be Future Forests.
posted by nthdegx at 5:05 AM on October 20, 2005

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