Inspector Gregory: “Is there any point to which you would wish to draw my attention?”
Sherlock Holmes: “To the curious incident of the dog in the night-time.”
Inspector: “The dog did nothing in the night-time.”
Holmes: “That was the curious incident.”
The analogy to global warming is that those who can understand the evidence, even when it doesn’t make obvious noise, understand the problem. Those who don’t, don’t.
Where’s the proof?
Hurricanes, fires, and droughts notwithstandng, the evidence for global warming lies in statistics. No single weather event can be pinned on global warming, any more than a specific price increase at a specific grocery store indicates inflation. Next summer could be the coldest one on record, and yet it would neither prove nor disprove the existence of global warming. Because specific events can always be found that contradict the general trend, it feels like statistics prove nothing, and since statistics are the only evidence for global warming, it feels like global warming has no proof.
But, actually, statistics do sort of prove things. Let me explain.
Statistics aren’t proof in the common meaning that there is 100% certainty. However, in day-to-day life we make almost every decision without proof. Which college to go to, which presidential candidate to vote for, which house to buy, which job to take, these are all things with elements of uncertainty where we place bets and hope for the best.
Depending on the consequences of betting wrong, we’re less tolerant of risk. If my house turns out to be on top of a superfund site, and that means I have 20% excess chance of getting leukemia, I won’t wait till I get leukemia before moving out. That kind of certainty, I don’t need.
Statistics can indicate which bet we’re likeliest to win, and it can do so to a much, much higher degree of certainty than we have in almost every aspect of our day-to-day lives. How many people wait to invest in a mutual fund until they are sure it has a better than nineteen to one chance of exceeding its previous returns? That’s the standard of acceptability in biological sciences. After the study has been confirmed many times, it’s considered very likely to be right. “Very likely” in that case would be more like several hundred to one. That kind of certainty about a mutual fund would make it a better bet than US Treasury bonds.
On the other hand, statistics can also be used as in the phrase, “Lies, damn lies, and statistics.” This, however, isn’t the fault of statistics, any more than Latin is at fault when a priest puts one over on us by speaking authoritative gobbledygook. The difficult part, for those of us whose statistical abilities are nonexistent, is to evaluate when the numbers are being used truthfully, and when not.
It’s not as difficult as it might seem, although you’re on your own to figure it out. The media don’t help at all. Dramatic tension, which packs in the viewers, requires opponents, so the media will find opposing points of view even if there’s only one and a half scientists on one side, and 99,999 on the other. (Yes, I’m thinking of the “intelligent” design vs. evolution debate.) Although the media ignore it, the consensus among independent scientists is the main indication of whether scientific conclusions (which are always based on statistics) are lies or good guesses. Keep an eye out for boring statements like “95% of scientists think X, 3% think Y, and 2% are on sabbatical.” X stands an extraordinarily good chance of being true in that case. With that kind of informed consensus on a stock market tip, you could bet the farm and win.
In the case of global warming, there are two layers of statistics. There are the numbers concerning temperature, ice melting, ocean currents, carbon dioxide sequestration, and so on and on and on. Then there are the numbers of scientists who are convinced by the research that global warming is in progress, and that it is due to human activities. In recent years, the number of scientific specialists convinced by the research has grown vast. It’s near 99%. You can bank on that type of consensus, especially when the opposing voices are loudest among those funded by Big Oil.
Global warming is happening, and it’s due to human activities.
What does global warming mean?
The other problem with perceptions of global warming is the inability to understand what it means. We hear numbers like “five degree average rise in global mean annual temperature,” and our eyes glaze over. Five degrees? Good grief, we think. We won’t even have to turn up the a/c.
Keep in mind that the last Ice Age represented approximately 7C drop in temperature. Mean annual temperature is a meaningless number, just as the average height of human beings tells you little about the height of, say, your uncle. The mean rise is composed of much warmer temperatures in the hot, dry interiors of continents. Texas, for instance, could go from having summer highs of 105F to 120F. That’ll do a lot more than raise electrical bills, or even than increase deaths among vulnerable people. Crops won’t grow well in that kind of heat, and will require massive irrigation. Cattle will die. And wildlife will be decimated. Before you think that’ll be the least of our worries, remember that insects are wildlife too. And if the natural enemies of, say, mosquitoes, are gone, we’ll have clouds of mosquitoes and of the diseases they carry. Start with malaria, go on through dengue, and you start to get the picture.
Ocean levels will rise, even if there is no ice melting (and there is ice melting). Air expands when heated, and so does water. The effect is miniscule on the scale of a pot of water, but it is huge on the scale of an ocean. Expected rises in temperatures are projected to lead to about a meter rise in sea levels, based on thermal expansion alone. This is not a calm process where every year things just seem to get a bit damper underfoot if you live in Miami. What happens is that one day a storm blows through and floods occur where they didn’t before. There is no effect if the flood doesn’t happen to soak you. If it does, your whole livelihood, even your life may be destroyed.
There is no comfort in the fact that even awful local disasters are overcome, in time. The point with global warming is that there will be more frequent and larger disasters, and sooner or later, nobody will be immune. After Hurricane Katrina, Rita would not have weakened (because the warmer water near Texas would have sustained it). Then a Category 5 would have taken out Galveston. Imagine, a week later, if another Category 5 had taken out Miami. At 200,000,000,000+ in damages for each one and the two major centers of energy production decimated, there would have been a national recession. That would affect everyone.
So far, I’ve sketched out famine, pestilence, and flood as consequences. War wouldn’t be far behind. The people displaced by catastrophe will try to move to places where they can survive. Other people will try to replace resources lost in disasters by taking them from someone else. People who lose their living may become entrepreneurial robbers or meth cooks. The politicians will be “realistic” and “tough-minded” and will make the “hard choices” involved in dealing with the situation “as it is now.” They’ll be too busy selling wars to waste money on switching over to non-carbon energy sources and to removing carbon from the atmosphere. (If you can think of current examples of these future scenarios, there’s a good reason for that. The process has begun, and the future has arrived.)
Not all places will grow hotter. Some will become colder. There are several indications that global warming could cause the Gulf Stream to stop flowing. Europe would look like Newfoundland, or colder. That would have a massive economic and agricultural impact. It wouldn’t mean much to them that the global mean annual temperature was actually up.
And that was the good news.
The bad news is what happens if global warming spirals out of control. Venus is described as a planet with a runaway greenhouse effect. Earth is too far from the sun to have a surface temperature of 890F. But 200F would be plenty bad enough. Vast quantities of carbon are fixed in arctic peat bogs. The permafrost there is starting to melt, and they’re starting to exhale their carbon. Coral reefs sequester masses of carbon into limestone where it stays for millions of years. Warmer oceans would be more acidic, which dissolves limestone faster, which liberates increasing amounts of that carbon back into the atmosphere. Just because we stop behaving like idiots, doesn’t mean the feedback loops we’ve set in motion will stop too.
That means that if we don’t prevent global warming before the symptoms become acute, flood, fire, famine, pestilence, and war could look like nice problems to have. What we are doing here is taking the chance on making our whole planet unlivable. Is that outcome likely? No. Does it therefore make sense to take the chance? Only if you’d be happy raising your kids on top of a superfund site. We’re okay with other people having to take that chance, but nobody on Earth, speaking for themselves, would say anything but, “Hell, NO.”
We have only this one planet. The loaded gun isn’t pointed at someone else. It’s pointed straight at my head. And yours.
What to do?
There is really only one thing to do. Start reducing carbon, methane, and other greenhouse gas emissions now. We’re past the stage when we had the luxury of tapering off slowly. We’re even past the stage when we could afford to hold levels constant and reduce gradually. The exhaling peat bogs and quietly bleaching coral reefs are telling us that. Even the Kyoto accords are too little too late. We have to start reducing, and we have to start now.
That means coordinated, global programs away from coal, oil, and all fossil fuels, even nice, clean-burning natural gas. Biodiesel, ethanol, and other biomass energy sources aren’t in that group because the carbon they release is carbon they fixed within the previous few years. They don’t reduce carbon in the atmosphere, but they don’t increase it either. Active carbon sequestration is a good idea, if done right, but, by itself, it couldn’t be done on a sufficient scale to reverse all the decades of carbon liberation. Nor is there any way it could compensate for continued carbon profligacy.
The main thing to do is to stop pumping carbon out. Solar, wind, tidal, and all clean alternative energies, as well as efficient mass transit systems, need to be perfected and promoted in nationwide efforts worthy of wars. This isn’t an exaggeration. Even the good news about global warming means that we’re fighting for our survival here. A war effort might be enough. We have to hope. Less than that probably won’t be.
It is also pointless to piss and moan about the expense. The expense of continuing our current course will dwarf anything we pay to switch to a nonlethal track. As a very minor case in point: The “impossible” cost of dealing with Louisiana’s levees, coastal erosion, and wetlands was around ten to twenty billion dollars. The price tag after Hurrican Katrina is at least two hundred billion, and that won’t get it back even to where it was before the hurricane, or pay for the lives ruined and lost. I am not joking or exaggerating or using poetic licence when I say that the expense of cures will only get worse compared to that of prevention.
Well, you may say, it doesn’t matter. Nobody’s going to spend money they don’t have to. Just make the best of it.
Unfortunately, I agree with that. Unlike nuclear war, which terrified people, global warming sounds rather benign, especially as the northern hemisphere heads into the season of sleet and ice. I cannot imagine that enough people will wake up to our mortal danger in time to avoid it. I hope the real problem is my lack of imagination. But that’s why the original title for this piece was going to be: Global Warming: Be Afraid. Be Very Afraid.
RealClimate is a commentary site on climate science by working climate scientists for the interested public and journalists.
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