Global Warming...

Great Debates
41

Gb: I’m not in favor of reducing any forward progress in the area. I like less pollution and greater efficiency.

Oh, okay then. In that case, I would think that you’d be happy about environmental efforts that unquestionably result in less pollution and greater efficiency.

Gb: I’m merely against further expenditure of effort until we know with reasonable certainty that our efforts will solve the problem. Or are we not supposed to be solving it?

We do know with reasonable certainty that our efforts will at least substantially reduce the problem of overloading the atmosphere with greenhouse gases. And we also know with reasonable certainty that reducing that overload will probably reduce the likelihood and severity of catastrophic climate changes.

None of this, of course, is likely to have much effect on the likelihood or scope of long-term, non-anthropogenic climate changes of the sort that the earth has always experienced. (Except insofar, as jshore points out, as we may have already overwhelmed some of those effects with anthropogenic changes.) But I don’t think it makes any sense to refuse to address the short-term, more drastic problem just because it won’t solve the more remote problem at the same time.

Gb: Since we have limited resources at our disposal, I propose analyzing the problem thoroughly and dealing with it effectively, not merely prolonging it.

If time weren’t an issue, this recommendation would be reasonable. The trouble is, though, that the longer we go without addressing the problem of anthropogenic change in the atmosphere, the more we exacerbate the resulting problems. This is a case where an ounce of prevention really is worth a pound—perhaps several pounds, or maybe even tons—of cure.

Gb: * You may be right though, it could be really stupid to direct our efforts into practices that produce some sort of tangible results.*

But emissions reduction does produce tangible results: it slows or reverses the drastic changes we’re making in the composition of the atmosphere and minimizes our disruption of climate equilibrium. It’s madness to refuse to make such tangible, constructive changes just because we haven’t yet figured out how to accomplish such comparatively superhuman tasks as stabilizing the planet’s whole freaking orbit or shielding its whole freaking surface from excess radiation.

Gb: All very nice but my point still stands, the bomb went off before regardless of human interference.

Look. God or geophysics or what have you has placed our whole planet in a climatological minefield. Things can happen, and have happened, and at some point will doubtless happen again, in our climate that are not good for fragile human beings. We’re not going to get out of that minefield any time soon, fantasies about atmosphere shields and orbit stabilizers notwithstanding.

But now, thanks to our massive atmospheric emissions, we appear to be standing in that minefield holding a hand grenade with the pin pulled out. You’re arguing that we should tuck the grenade into our pocket, not bother putting the pin back in, and instead just concentrate on what it would take to detect and deactivate all the mines. In terms of a prudent near-term strategy, this is completely nuts!!

And while my ideas seem ‘wild,’ I’d like to get a rough estimate of the combined cost of all the reforms we’ve undertaken in the past couple decades before I discard the ideas. Recycling centers, emissions testing, research and development, endangered species protection, legislation and the litigation necessary to ensure the legislation is upheld, raw manpower studies…as a social project, the environmental movement probably hasn’t been inexpensive.

It’s probably not more expensive than unchecked pollution. Recycling, according to a recent Straight Dope column, is sometimes more expensive than conventional disposal and sometimes cheaper. The health costs of polluted air and water are considerable, and it’s probably cheaper even in purely economic terms to regulate them, at least in heavily populated areas. And you can just ask anybody in Florida whether severe weather events (which are predicted to increase in frequency with increases in planetary warming) come expensive. And as jshore has already pointed out, companies have often found that environmental regulations end up saving them money.

Gb: Now a simple question: are we, or are we not, in danger? What kind of danger? Extinction? Dark Age? Give me an idea so I know.

Well, Sentient and jshore have been plastering the thread with links to climate science reports, so you might want to try reading some of them to get an idea of what some of the possible outcomes are. (How can you have such definite opinions about environmental policy if you don’t yet even have any “idea” about what the predicted consequences of our current actions might be, anyway?)

Gb: *Decrying the horror of it is encouraged, making personal lifestyle changes is lauded, damning The Man is required and solving it is said to be infeasible except through the increasing adoption of practices and values that smack distinctly of Luddism. *

Luddism? On the contrary, a lot of conservation technology these days is extremely cutting-edge. In fact, one of the things I like best about environmentalist thinking is the scope it affords for tremendously practical inventiveness and cleverness. Regenerative braking, new photovoltaic films, passive solar heating, wind turbine and engine designs—there are some damn clever people coming up with some damn good ideas in this area! (In fact, I wish more of them were American, as I’m afraid we’re going to lose some competitive edge if we cling to our twentieth-century technologies too long.)

You’re complaining a lot about the “religiosity” of environmentalists, but it seems to me that the environmentalists are the ones being practical and scientific here, in this thread at least. They’re presenting actual data and peer-reviewed research, advocating policies based on data and research, and trying to quantify actual economic costs. You’re the one offering nothing but portentous vague doomsaying and empty generalizations.

42

Well, it has also yielded lots of benefits. And, yet the estimates for the number of deaths per year caused by air pollution in the U.S. is still quite high…I seem to recall something like 10,000 or more. Also, these different things you talk about are dealing with various different environmental goals. For example, emissions testing is about controlling “traditional” air pollutants (like SO2, NOx, carbon monoxide, and mercury), not greenhouse gas emissions. And, when the EPA issues regulations they do study the costs and the benefits. They even have a dollar value they put on every life saved…I forget what it is.

At a more local level, the benefits and costs aren’t always studied as carefully. And, it may be true that some recycling may not be paying off…But, it tends to be true that any new system / technology often initially has higher investment costs than pay off, particularly until we learn to do it more efficiently. With recycling, some materials pay off more than others…For example, the payoff for aluminum recycling is particularly high because I think it costs something close to 10X as much energy to make an alumininum can from virgin ore than to make it from recycled aluminum. And, for other materials, like paper, the market for recycled goods is not that strong partly because we subsidize the cutting down of our national forests and thus the price of producing paper from trees is kept artificially low. (I am not sure how big the effect is.)

Well, the point is that we don’t quite know the full extent of the danger yet. Mainly, we don’t have a good enough handle on the sensitivity of the climate to buildup of CO2 and also don’t know quite where the tipping point is for where things like extensive melting of the land ice and corresponding rises in sea levels becomes a reality. But, we do know that the sort of CO2 levels that will exist in the atmosphere if we burn all of the fossil fuels available will be quite astronomical…I forget the exact numbers but I think it is on order of 5 to 10X the pre-industrial concentration, depending on whether we use only conventional fossil fuel sources or both conventional and unconventional. It is important to note that the IPCC has focussed almost exclusively on effects over the next 100 years but in fact some of the effects, such as melting ice and rising sea levels, will continue for hundreds of years after we have stabilized CO2 levels in the atmosphere. So, it is pretty clear that at some point we are going to have to do something about converting to non-fossil-fuel energy sources or sequestering CO2 or likely both.

At this point, the best thing to do is to “hedge our bets” by “buying some insurance”. You don’t wait until your house has caught fire before you go buy fire insurance. In this case, the “insurance” comes in the form of trying to stabilize emissions, invest in new technologies, and perhaps most importantly, to internalize a cost of CO2 emissions into the marketplace so that it becomes profitable for companies to invest in technologies that reduce the emissions.

kimstu dealt with this point but I will only add that, although I am often somewhat of a Luddite concerning new technologies, I made a break with that in the case of cars when I bought my 2004 Toyota Prius, a hybrid. And, to be honest, now when I look around everyone else sort of seems to be Luddites…At traffic lights, their cars remain idling for no real good reason while mine (usually) stops completely, and when they brake their cars convert all that energy of motion into wasted heat whereas mine uses a good portion of it to run the electric motor in reverse as a generator and charge the batteries. And, what kimstu says about the dangers of the U.S. falling behind in such technology definitely rings true. I think Toyota claims something like 300 patents on hybrid technology and when the Ford Escape hybrid SUV makes its debut very shortly, it will be using that technology licensed from Toyota (and I think a lot of the hybrid components in it are Japanese-made too).

And, in case you get the impression that the use of such technology is on the fringe of the environmental movement, I’ll point you to this Sierra Club website showing their “I will evolve” ad campaign geared to youth and trying to encourage people to support and buy hybrid and other clean energy technology. I think this whole claim that environmentalism has become some religion is a very deliberate tactic being pushed by those, like the fossil fuel lobby, whose self-interest is actually in not adopting this new technology. (It is admittedly aided by a few extremists on the environmental side who have a quasi-religious perspective on it. But, there is a very deliberate attempt to use these and then bait-and-switch to tar mainstream environmental views and policies with this in order to make it seem like mainstream environmental policies are dictated by quasi-religious views rather than hard science.)

43

I agree that uncertainty is not an excuse for inaction. But neither is *possibility an excuse for extreme action. Rather, uncertainty can be plugged into an economic model to allow us to optimize our decisions.

Let’s say we come up with a model that says there is a 20% change of warming small enough to maybe even have a small net beneficial effect, a 60% chance of being moderate but severe enough to have a worldwide cost of trillions maybe 50 years from now, and a 20% chance of extreme heating that could have disastrous consequences in 100 years. That data can be plugged into a formula using the time-vaue of money to come up with a reasonable range of costs for current action.

Then the other part of that equation is, what is the effect of what we can do now? If spending 1 trillion dollars changes the equation to 25/55/20, is it worth it?

My skepticism does not come from the science, but rather from the tendency of the environmental movement to completely ignore the costs of their actions, and focus only on the benefits. Two examples come to mind: The ban of CFCs, and the ban on the use of DDT. Both had immense human and economic costs that, at least in the case of DDT, severely outweighed the potential benefit of a ban, in my opinion. Malaria was almost eradicated through the use of DDT, and after it was banned the rates of malaria death in the 3rd world skyrocketed. We’re talking about millions of people who have died unnecessarily.

The tragedy is that DDT’s negative effects were almost completely due to inappropriate use in widespread agricultural spraying. A compromise was possible which would have allowed DDT to stay on the market for most uses but be banned only in certain applications. (and it did, to some extent, especially later on, but not enough). But the greens’ scare tactics and refusal to budge went way over the line and did tremendous damage.

CFC’s are another example. What were the costs? Aside from the economic cost of having to replace millions of air conditioners and refrigeration units, the increased costs of refrigeration cause it to be used less in marginal situations, resulting in more 3rd world malnutrition, deaths from food poisoning and stomach cancer. But hey, the rich white people could suntan more! Are we better off for having banned CFC’s? Perhaps. Maybe even probably. But it’s hard to tell, because we never had the debate. Again, scare tactics and protests shut down debate and we never really discussed the costs.

I’m also skeptical of the environmental movement because they are so anti-capitalist - one gets the sense that many environmental ‘solutions’ they espouse are less about the environment and more about socialism and gaining control over people’s lives.Jshore is a notable exception, and I appreciate his willingness to examine market-oriented solutions. The environmental movement needs more moderate, science-based people like him. But unfortunately, it’s top-heavy with raving, uneducated lunatics.

We need rational environmental policies which take into account the costs and benefits of both inaction and action. And where action is warranted, we need the flexibility to consider all possible solutions, including accepting costs where they are reasonable and simply paying to fix the damage. Nuclear power is a good example of where greens refuse to cooperate. If global warming is truly a threat to the well-being of the entire world, then nuclear power is a no-brainer. It’s the only power source we have that can conceivably replace fossil fuels while emitting no greenhouse gases.

Dick Cheney was right - conservation is a personal virtue, but it’s a lousy basis for an energy policy. Conservation can only affect us on the margins. Our energy dependence comes from the cost of making goods, shipping them around the country, moving us to work and back, heating homes, building and repairing roads, etc. Many of these activities simply can’t be scaled back without immense cost. You can turn down your thermostat, but you can’t reduce the number of trucks moving goods into your city without serious consequences. You can drive a more efficient car, but you can’t remove the energy the factories and mines needed to expend to build it.

Conservation might allow us to lower our overall energy consumption by maybe 10%. But since worldwide consumption is increasing by 1-2% per year, all that does is move you a few years back on the curve. It’s essentially meanginless in terms of an overall energy policy. Likewise, solar, hydro, and wind power can have a small effect on the margins, but they are unstable sources unsuitable for meeting peak loads 24/7. We should build more of them where the costs are in line with other energy costs, but those technologies will never have more than a marginal effect on our energy requirements.

Fusion power is still a pipedream. It’s 30 years away, and has been for the last 30 years. We may never achieve economic fusion power. We certainly can’t hang our future on it.

So what’s left? Nuclear. It’s clean, its cost in in line with other power sources, it can be concentrated, it’s available 24/7. We should be building nuclear power plants like mad, but the greens stand in the way.

44

I agree…the only real solution is the widespread adoption of nuclear power. What the anti-nuclear people do not realize is, that nuclear technology has come a long way…the reactors we are running today were designed back in the 1950’s…we have designs today that are much safer, and more efficient. A well designed nuclear p[ower plant can be made totally foolproof-it will shut itself down automatically (in an emergency situation). Chernobyl was an old, defect ridden reactor.
Quite apart from the fact that nuclear power plants don’t emit CO2, there is the benefit that they use much leass energy in running the plant-for example, you don’t have the energy costs of transporting coal or oil to the plant.
The radioactive waste problem is overblown-you can process it and encapsulate it, and then it can be safetly buried. Of course, the environmentalists have held this up as well-we have a perfectly good repository in NV, but the anti-nuclear crowd has help this up as well.

45

SS: CFC’s are another example. What were the costs? Aside from the economic cost of having to replace millions of air conditioners and refrigeration units, the increased costs of refrigeration cause it to be used less in marginal situations, resulting in more 3rd world malnutrition, deaths from food poisoning and stomach cancer.

Do you have a cite for this? The compliance costs of the CFC ban were definitely overestimated by industry, as often happens. As this “Science Matters” article notes,

Given that the direct economic costs of CFC regulation turned out to be much less than anticipated, I’d like to see evidence that the indirect costs due to refrigeration-related disease are significant. In particular, given how recent the CFC ban is, I wonder how they managed to gather data about long-term medical consequences such as stomach cancers.

SS: But hey, the rich white people could suntan more!

You do know that non-white people get skin cancer and other UV-radiation-related health problems too, right? In particular, considering that about 2% of the population of India has cataracts, for which most of them can’t afford corrective treatment, they definitely don’t consider ozone depletion just a “rich white people’s” problem.

SS: * Conservation can only affect us on the margins. *

The margins are pretty thick, though. For example, it’s estimated that modest increases in fuel efficiency standards for vehicles could save 1.5 million barrels of oil per day, or over 5% of our total oil consumption. Serious commitment to easily achievable and inexpensive conservation measures can indeed end up saving us some serious money.

SS: We should be building nuclear power plants like mad, but the greens stand in the way.

As I’ve said before, though, we can’t expect fears about nuclear energy to diminish until we improve our safety and oversight record for existing nuclear plants:

It’s interesting that most European countries, which tend to be more socialistic and to have a larger role for strongly environmentalist political parties such as the Greens, are also more accepting of nuclear power. I think that this is at least partly because the citizens feel more assured that the governments actually take the safety and regulatory issues seriously.

SS: *The environmental movement needs more moderate, science-based people like [jshore]. But unfortunately, it’s top-heavy with raving, uneducated lunatics. *

Alas, there are too many ill-informed ideologues on both sides of the debate. Unfortunately, they tend to be the ones who get the most attention and shape the debate’s terms.

46

Absolutely! That is the definition of “incontrovertible”.

Where is it?

What the heck is wrong with energy efficiency?

47

Nothing. Not a damn thing.

But “conservation” is an energy source only in the same sense that “dieting” is a form of agriculture.

48

Agreed, but if you’re so obese that there is a real risk of your health abruptly changing for the worse in future, do you diet, or do you eat even more and simply make sure that those extra helpings consist of low-calorie poison?

49

That is what the Science article that I linked to tries to do. I would say that this area of economics is still not all that advanced. For example, as impressive as many of the macroeconomics models are, I don’t think any of them can deal well with imperfections of the market…e.g., they all would predict that it would have cost BP money to do what they did rather than that it is saving them money because otherwise they would have done it already.

But, at any rate, the point is that this is what is being attempted now in several studies.

We had a thread on DDT a ways back. Suffice to say that this view of the story has many holes in it. I’ll try to link to the thread later.

Well, I appreciate the compliment. But, I don’t think your view of the environmental movement is that realistic. I think there has been a successful attempt to pain it as being much more extreme than it is, at least if you talk about the mainstream environmental groups and ignore minor players who are extremist like Earth First!

Dick Cheney was dead wrong, as usual. Conservation is the fastest way to make changes. Yes, it works at the margins…But, that is where everything works. You don’t get that much more energy with each additional powerplant but it adds up as you build more and more. It is the same with conservation except that the upfront costs tend to be less and the actions often pay for themselves very quickly. And, there is plenty of low-hanging fruit for saving energy (and money) in our factories and such. Companies like BP who have tried are finding that out…And the CEO of BP likes to point out that he believed his company was quite efficient to start with.

I would quibble with your 10% figure. But also, again, that is all that any specific thing does is work on the margin. As our technology advances, there will be more opportunities to become more efficient (“smart windows” for example). I am not saying that conservation alone will be able to do it but it is a very important part of the solution.

You’ve repeatedly made this “greens stand in the way” claim and yet have never been able to back it up. The fact is that nuclear power in the U.S. (which does provide 20% of our electricity) has failed to grow recently because it is not economical in comparison to other options. In places like France and Japan, it has been more successful not because the greens are any less strong there from what I can tell, or that nuclear is any cheaper there, but because fossil fuels are more expensive.

What the nuclear power approach comes down to is huge subsidies for an already-quite-mature technology (and a technology that does have some serious environmental & security issues that need to be considered). Rather than do that, we should level the playing field by reducing subsidies for fossil fuels because that is the real thing that is out-of-whack. Of course, the Bush Administration wants to move us in the opposite direction of more subsidies of fossil fuels and then big subsidies for nuclear. This disadvantages the new renewable technologies which are the ones that should really be getting most of the subsidy at this stage and also encourages us to use energy inefficiently rather than efficiently.

50

Well you do have to mine and then transport the uranium and I have heard that the mining is moderately energy-intensive although I haven’t seen any hard figures on that. Admittedly, the transport should be less so since it such a compact fuel source.

51

Sam, try this if you get a minute. I ran a few numbers through excel to model a x % per year decrease in energy use (conservation) and a y % per year increase in energy consumption. To make it fair I delayed allowing the conservation factor until the second year.

E[sub]n[/sub]=E[sub]n-1[/sub]*(1+y%) – E[sub]n-2[/sub]*x%

Just take a quick look at the results over 15 years from a staring value of 100 using a 2% conservation factor and a 3% growth factor. After 15 years energy consumption is up 17%, but without conservation the increase is 51%.

Now I’ll admit this is rough but if we apply this to Canada’s electrical consumption (504.4 billion kWhr in 2001) and use $0.05 per kWhr then the savings total 54 billion dollars over 15 years. For the final year the cost difference is 8.5 Billion dollars.

What I’m trying to show is that small increases allow for greatly magnified results over time due to the exponential nature of energy use. The added value of reducing emissions is icing on the cake to an extent

52

The problem with that analysis is that you just pulled those numbers out of the air. You can show anything that way.

Your equation assumes that we can maintain a constant annual increase in conservation. But that doesn’t seem likely to me, because we will very quickly run into the law of diminishing returns. Once we get past the ‘easy’ measures like turning the heat down a few degrees and remembering to turn our PC’s off at night, it starts to get harder. More fuel efficient cars? Great, except that it takes a long time for those cars to displace the existing fleet - a couple of decades. And if you force those cars on people when they aren’t willing to drive them, they won’t buy them. So then you’re left with putting taxes on energy to regulate consumption, and that is very expensive for the economy.

But once you’re past the point of easy personal conservation, it gets much harder. The bulk of our energy is burned in our manufacturing and distribution of goods. Most of these operations are already pretty energy efficient, because it’s cheaper up to the point they’ve gone to. Try to push them past that and you start getting into the realm of major infrastructure upgrades and wide scale disruptions of the market. Very , very expensive.

And even if you do all that, all you do is push the problem down the road a few years.

The only way to solve this problem is to find a different source of energy, and/or learn to sequester our carbon. We have to get the level of CO2 emissions down below the level of the Earth’s moderation forces to absorb it. Once we reach that ‘safe’ level (which is NOT 0 emissions), we can still use our fossil fuels, but as a much smaller source of energy. Remote turbines, that sort of thing.

The only energy source that we have available today that fits the bill is nuclear. Yes, it has risks. But they aren’t the kind of risks that can wipe out the ecosystem. Localized spills, expensive cleanups, localized harm. That’s essentially the risk. Even long-term storage, if it develops problems, is mainly a matter of engineering and expense to fix.

And even that risk is minimal. Nuclear power has gotten very, very safe. If you truly believe that CO2 emissions are threatening the planet, I don’t see how you can not support it.

53

Why don’t volcanic events have long term impacts on greenhouse gas levels? Is it simply that volcanoes don’t release as much material as I’ve been led to believe? I’ve heard it quoted that a single large eruption will release more CO2, etc. than humanity generates in a decade. If they do generate that much stuff… where does it go?

Related: I’d guess, CO2 especially, it could be abosrbed/dissolve in the oceans. However, the solubility of gases are affected by temperature. So couldn’t there be a positive feedback thing at work here? Temperatures rise, solubility goes down, greenhouse gases are released into the atmosphere, causing temperatures to rise… etc.

What’s wrong with the above?

54

Some biologists ahve postulated that increased levels of CO2 might actually stimulate the growth of green plants…so much so that the extra CO2 would be absolrbed. That experiemental dome in Arizona: didn’t they study the effect of increasing CO2 levels? What happened there? I also wonder that if global warming is a real effect, then large areas of the arctic should begin to support plant life. This increase in biomass should absorb quite a bit of CO2 as well.

55

According to this figure on the carbon cycle, volcanoes emit ~0.1 billion metric tons of CO2 per year (although I would guess there might be fairly large year-to-year fluctuations). By contrast, burning of fossil fuels emits 5-6 billion metric tons per year. So, the answer appears to be that volcanoes just don’t emit very much CO2 in comparison to our fossil fuel emissions. (Here is a figure from the IPCC which shows the same thing. In fact, they list volcanoes as <0.1 billion metric tons and the total human perturbation as being 5.4 metric tons…)

In fact, what volcanoes do emit a lot of is particulates that can actually cause a cooling over a period of a year or so, until much of these particulates are washed out of the atmosphere. The Krakatoa (sp?) eruption in the mid-1800s led to the so-called “year without a summer” over much of the U.S. And, I believe that climate model simulations studying the recent past actually include such cooling effects due to specific eruptions in their natural forcings.

Could be…I’m not sure. The absorption of CO2 by the oceans is a complicated process. In addition to the issue of ocean temperature, there is also the issue of how much mixing there is of the water between the surface and deeper because the surface layer can easily become saturated with CO2 but with the deeper water still not saturated.

56

So, do we just ignore the data point from BP in this regard?

57

You do appear to be right on this point although I don’t know how big an effect this is believed to have. Here is what the IPCC has to say about this and other physical processes that can effect the uptake of CO2 by the oceans:

They go on to discuss some biologically-linked processes that affect the re-uptake of CO2 by the oceans but I’ll let you read them directly from the link. And, on this page they return to the issue when they discuss modeling of future uptake of CO2 by the oceans:

58

Short answer: Yes, there is expected to be some increase in uptake of CO2 due to this and this is something that is being taken into account in the modeling of the carbon cycle. Here and here are two relevant pages from the IPCC report.

And, here from the technical summary of the IPCC report (which you can download as a PDF file) is sort of the bottom line on the carbon cycle:

Also from there is a summary of the human perturbation to the atmospheric carbon budget for the 1990s: 6.3 PgC/yr were emitted through burning fossil fuels and cement manufacturing. Of this, ~1.7 PgC/yr was taken up by increased uptake of CO2 by the oceans and ~1.4 PgC/yr by increased CO2 uptake by the land, leaving a net increase of 3.2 PgC/yr in the atmosphere. [The 6.3 and 3.2 numbers are known quite accurately whereas the partitioning between ocean and land uptake is known less accurately…although, if I remember correctly, there may have been some recent progress in this since the IPCC report was issued.]

59

By the way, as this article notes, the last couple of years have seen an acceleration in the increase of CO2 levels in the atmosphere. Since there tends to be a fair bit of variability from year-to-year, it is too early to say whether this is a trend or just a fluctuation:

60

This is the only rational way to approach the issue. We’ll probably never be certain enough of human impact on climate to silence the critics of the theory; at least, we won’t know enough until it is too late to do anything about it. There are enough good reasons to curb polution without global warming, I sometimes wonder why it’s as big an issue as it is. I suspect the opponents of emissions reduction like the uncertainty of this particular issue, because it allows them to argue that all findings are negated because one theory cannot be proved to their satisfaction.

Be that as it may, if humans can impact global climate as much as some suspect, rapid and potent changes could occur over the span of decades, vs. the millenia most once thought was the relevant time scale. That means our grandparents may have already impacted our climate quite noticibly, and our grandchildren may feel what we do today quite palpably. I find the idea rather chilling (if you’ll excuse the pun). In my parents’ home town, up in the hills of Maine, I can remember many winters when the snow would get so high that you couldn’t see out the ground-floor windows of my grandparent’s house in January. Now sometimes I go there in January, and there’s no snow at all. For the past twenty years, there’s never been more than two feet of snow on the ground, even after a big storm. Maybe this is a natural trend, but in any case, the evidence (which I don’t need fancy science to observe) is truly striking. I’m only 34, and my childhood memories of northwestern Maine look like a mini ice-age by comparison to today. It’s not just my imagination, either; everyone I’ve ever spoken to acknowledges it, and it actually gives the older folks the creeps.

So if human beings are responsible for the change, it’s quite alarming. What could happen fifty years from now? The fact we can’t easily predict it shouldn’t be a reason to feel comfortable. You’re not being Chicken Little when all the available evidence clearly points to the fact that something dramatic is happening, and that there’s plenty of room, according to the fossil and geological records, for the trend to swing further. If you can’t safely predict quite how dramatic the future change will be, but know the limits, and you can’t predict with 100% confidence that human influence is responsible, but you know it could be, is there any rational cause to wait for absolute certainty before acting? I think not.