The current situation of the world in relation to the climate problem is that we’re in a car with bad brakes driving toward a cliff in the fog, and the fog is the scientific uncertainty about the details that prevent us from knowing exactly where the cliff is. The climate change sceptics are telling us that the fog is a consolation and that we shouldn’t worry because we’re uncertain about the details, but of course any sane person driving a car toward a cliff in the fog and knowing that the brakes are bad, that it takes the car a long time to stop, will start putting on the brakes, trying to slow the car, without knowing exactly where the cliff is but just in the hope that by putting on the brakes we’ll be in time to keep from going over the cliff. You don’t have to be sure that you can still avoid going over the cliff to put on the brakes, you want to do it in any case. And that’s what the world should be doing with respect to the emissions of greenhouse gases that are causing this climate problem. There’s a chance we’ll go over the cliff anyway but prudence requires that we try to stop the car.

– John Holdren, Feb 2007

I can’t say how relieved I was to hear a senior White House official say this.  After so many years of absurd denial, the U.S. finally has an administration willing to deal with reality.  Of course the most extreme climate change deniers will assert that the planet isn’t really warming at all – that this is somehow a grand conspiracy of climatologists to secure funding.  I think anyone has got to start being incredibly doubtful when massive conspiracies are raised as the justification for anything. This is crazy talk, and we should recognize it as such. Furthermore, it is a completely unprincipled ad hominem attack on climate scientists. You could just as easily claim that the belief that drugs and other medicines can treat diseases is a conspiracy of the medical research and pharmaceutical industries to boost their profits and get funding. Similar claims could be made about any branch of science, or any field where there is group consensus of any kind.

There is a huge body of evidence for global warming, coming from a variety of very different sources. It is true that there are real questions and uncertainties with the data and the science behind it. All data from the real world has uncertainties built into it, and experts will debate the data, the methods and the strength of the conclusions. However, just because there isn’t universal agreement about everything doesn’t mean that everything is bogus. Ultimately we have convincing data from many different sources which all tells a common story. When you have such convergent data as this, it is usually because there is something real behind it, not that it has all accidentally (or by insidious design) been shaped to delude you. Claiming that there is no warming climate is equivalent to driving towards a cliff in the fog in a car with bad breaks and the guy in the back seat is questioning whether or not the map which shows a cliff nearby is a devious fabrication. “There’s no cliff,” he says, “it’s all a conspiracy of cartographers.”ⁱ

For those still struggling to understand why a warming planet is like driving off a cliff, let me go into it a little bit.  Certainly, it is conceivable that the earth could slowly warm bit-by-bit. A warming planet will certainly have impacts on climate patterns, some places will become drier, others wetter, plants and animals will die off when things become too warm for them to survive, or they will migrate further north. Ice sheets will melt gradually, and the sea level will rise gradually. It is possible that all this could happen slowly over decades or centuries, and although this would certainly change the nature of the world completely, it is conceivable that we could find ways of adapting to it.

It does not seem like this is likely to be the case. There are a number of “tipping points” in the earth’s natural systems, which, if warming is pushed too far, will suddenly and dramatically change the whole dynamic of the planet’s bio-physical cycles. Complex physical systems, like the climate, tend to involve many overlapping and interacting factors, like the basic cycles of water, carbon and nitrogen. The idea of human-generated (anthropogenic) climate change is that by burning fossil fuels and using artificial fertilizers, we’re interfering with the carbon and nitrogen cycles.

In the water cycle, water evaporates from the sea, lakes, rivers, and from the land into the air, it moves with the wind and eventually forms clouds, which dump their water in the form of rain, snow and hail back onto the surface of the earth. The precipitation of water out of the atmosphere acts like a negative-reinforcement on atmospheric moisture.  If too much moisture gets into the air, it is more likely to precipitate out, if the air is too dry, it is more likely to absorb surface water. This is a self-regulating cycle that tends to keep atmospheric moisture fairly stableⁱⁱ. It is a negative-reinforcement cycle, because whenever it moves too far out of balance, an opposing factor comes into play which pushes it back towards that balance point.

A positive-reinforcement cycle, however, tends to be very unstable. Small changes will initiate processes which promote those very same changes. It is like an avalanche, where a tiny disturbance can shift a small amount of snow, but this movement then triggers more snow to shift, and the process continues until a vast wave of snow pours down the mountain, crushing everything in its path. Feedback in an audio system is another good example – if a microphone is placed too close to the speakers to which it is connected, it will pick up the sound coming from those speakers, which is run through an amplifier, and then sent out through the speakers. The result is that any slight sound picked up by the mic will quickly be transformed into a deafening roar of white noise, which continues until the system is switched off.  Of course, there are a bunch of parameters which are key to this self-reinforcing cycle. The distance from the mic to the speakers and the sensitivity of the mic are key. If the mic is outside of the appropriate range, it won’t pick up the sound of the speakers. The degree of amplification is also important, because that is required to increase the sounds at every cycle. If there was no (or negative) amplification, the dynamic of the system would not build consistently, but rather tend towards a constant murmur or else subside into silence. Also, any time-delay in the cycle is important. With a simple mic, amp, speaker system in a room, the circuitry has very little delay, and so the build-up is nearly instantaneous. But if you ever talk with someone over skype, for example, where there is a considerable delay, you may find a slowly building noise in the background that eventually drowns out your conversation. This is feedback, but the delay in the skype connection means that it may take several minutes for it to build to the point where it drowns out a person’s voice. These factors define the “space” in which this feedback can exist. Jimmy Hendrix‘s revolution in rock music was the paradigm shift that feedback was not simply an unpleasant artifact of a technical system. He realized that he could play with and within these factors, to shape the noise and use it as a new medium for creating music.

The point of all this is that our planet’s bio-physical cycles contain some lurking positive-feedbacks. There is a vast amount of methane trapped in the frozen soil of the arctic tundra. Methane is a greenhouse gas. As the earth warms, and the arctic permafrost melts, this methane is released, increasing the warming of the planet.  The ice sheets in the arctic and antarctic reflect a good deal of sunlight back out into space. As these get smaller, more of that light is absorbed by the darker earth and water, thus increasing the temperature. The oceans absorb a good deal of the CO₂ in the atmosphereⁱⁱⁱ, but it is believed that this process may reverse as the oceans warm, and they may start emitting much of the CO₂ they contain, thus exacerbating the warming problem.

Of course, no positive-feedback can go on forever. There is always some other factor that intervenes to limit growth. With a speaker feedback system, there is a maximum volume that the speaker can produce, a maximum volume the mic will pick up, and a maximum signal that the amp can create – whichever is the smallest of these will determine the eventual point at which the noise will settle. No avalanche can keep growing forever, eventually it will run out of snow or mountain and stop. No population of animals can grow forever, eventually it will run out of resources. Likewise, there is only so much methane trapped in the arctic, only so much ice to melt, and only so much CO₂ that the ocean can spit out. The worry is that by interfering with the natural carbon and nitrogen cycles, we may push the planet’s temperature to the point where one or many of these positive-feedback cycles kicks in, thus making it impossible for us to stop the warming until one or other of these processes reaches its own natural end. The feeling is that the resulting planet is not one where we can live – it would simply be far too hot for humans, and for most other plants and animals to survive.  Hence the cliff.

The tricky part in all of this is that we don’t really know how much warming it will take for the permafrost melt to reach runaway levels. The same is true for the melting of the ice caps and the CO₂-absorbability of the oceans. Just as the speaker-system has certain “space” of factors which determine when feedback can occur, so too does the biosphere have a certain “space” in which runaway global warming will take place. There are also some self-stabilizing factors that may kick in. Higher temperatures means more water vapor in the atmosphere. Water vapor is itself a greenhouse gas, so that might be another positive feedback, however clouds reflect sunlight back into space, so more cloud cover could help cool the earth. Nobody’s really sure how much water vapor might help cool or hurt by increasing the warming. We simply do not know where that space is. Hence the fog.

Of course we all depend upon the energy we generate by burning fossil-fuels and the food we grow with modern fertilizers and farm equipment. Lets be perfectly clear about this point. If we just stop burning oil and coal, stop tilling the earth with chemical fertilizers, billions of people will die. We simply cannot sustain the current population of the world without this technology. Some cold-hearted people may claim that we have too many people, and that we simply have to accept that many will die if we’re going to move to a sustainable future for humanity. I sincerely hope that these people will be the first to offer themselves and their families up for voluntary starvation in the name of the greater good. I for one cannot accept this plan. It is true that we have too many people, and that we cannot go on destroying the earth to build ever larger populations of people to feed. However, the way forward is by tackling the problems head on. We need to plan a sustainable future for ourselves, not an apocalyptic one.

Transforming our society into a carbon-neutral one will not be easy. It will require replacing or refitting vast portions of critical infrastructure. It will require large investments of time, money, labor and above all ingenuity.  We have all these things, but there will be economic and social costs to putting them to work. We just have to have the political courage to make these changes, and hope that we’re in time to avert disaster. Hence the bad breaks.

A recent Op-Ed piece in the New York Times by Nobel-laureat economist Paul Krugman had some very interesting things to say about the economic cost of climate change. Not only are we driving towards a cliff in the fog in a car with bad breaks, but there’s a sick person in the car who we’re trying to get to the hospital. That is, we cannot simply stop driving (that would be the equivalent of letting him die), but if we go over the cliff, everyone will die. That is, we cannot simply bring our economy to a standstill to avoid climate change – the consequences would be unconscionable. However, we may be able to slow down and proceed carefully enough that we can avoid the cliff and get to the hospital. That would be the possibility of migrating to a low-carbon economy, where we can supply our needs without pushing the planet into uncontrollable warming.

The key question then, is how sick is our companion? This will determine how much we can risk slowing down and not let him die. Opponents of climate change policies will argue that the cost to the world economy will be too great, and that we can’t afford such a change. This is equivalent to our friend rapidly bleeding out. Whereas maybe he has just broken his toe, and its painful, but he’ll survive. This is what Krugman argues. He indicates a figure of roughly $160 per U.S. family per year in the near term for the proposed Waxman-Markey cap-and-trade bill. That’s just 0.2% of GDP. As a reference, the U.S. spends about 4.06% of GDP on its military.

1. Thank you, Tom Stoppard, this is one of my favourite lines of all time! [↩]
2. which is not the same as it being uniformly the same everywhere on the planet – which it clearly isn’t [↩]
3. which leads to the additional problem of ocean acidification [↩]