Here’s a cool set of graphs, from the Oracle Wikipedia:
These represent an analysis of the Vostok ice cores, drilled at Vostok Station in Antarctica about 1996. This is cool stuff – by analyzing the layers in the ice cores, which are reasonably presumed to be laid down in nice identifiable layers year after year, we can get a look at temperatures, CO2 content and dust concentration over the last 400,000+ years.
The current ice age started about 2.6 million years ago. Based on the evidence in the Vostok ice cores, other ice cores as well as a lots of other geological data, it is believed that the current ice age follows a pattern, with alternating long periods of cold and ice, punctuated by comparatively short periods of warmth and little if any ice. In the graphs above, note how, about 125,000 years ago, temperature in Antarctica were warmer than they are now; CO2 levels were comparable.
The curious part here is that scientists are of course eager to compare the Vostok ice cores to those gotten from Greenland. There’s a problem, though: When you drill ice core in Greenland, in many places, right around 125,000 years ago, you run out of ice – you hit the frozen remains of forests and grasslands.
The only reasonable conclusion is that, around 125,000 years ago, much if not all of the Greenland ice cap was gone – melted, slide off into the sea as icebergs, evaporated – in any event, not there. Grass and trees don’t grow on ice.
Now, the bottom of the Antarctic ice sheet ends somewhere before 400,000 years ago, and, as far as I’ve read, they’re not sure when, exactly, the last ice-free period of Antarctica occurred. Maybe the ice at the bottom gets squeezed out, somehow, by the miles of ice above it, or melts and flows out as rivers into the sea. Or, maybe, Antarctica itself was free of ice around half a million years ago. As far as I know, nobody knows.
So: let’s take a look at who is denying what.
Is the climate changing? Of course! All evidence suggests it’s changing now, because all evidence suggests IT NEVER STOPS CHANGING.
Is it getting warmer? SURE! And, based on the actual physical evidence of the ice cores, it’ll most likely continue getting warmer – until whatever made the previous 4 inter-glacial periods end makes this one end, too. May have already started to happen, based on the last 20 years of data.
Is man’s activity contributing to climate change? SURE! I would reasonably suppose every activity on the face of the planet and under the seas affects the climate. For example, you can only get CO2 in the atmosphere if there’s O in the atmosphere – and something like 80% of the oxygen in the atmosphere got there because of all the plant plankton in the ocean. So plankton are affecting the climate big time, probably a lot more than people are. But we do everything from burning oil to cutting down forests to planting crops – we would have to have some effect. How much is open to question. Not a super lot, based on the how much background variation is already present, as evidenced by those ice cores.
Note, however, that people only started putting possibly significant amounts of carbon into the air about 150 years ago – yet, the pattern of higher temperature evidenced by the Vostok core analysis shows the current cyclical warming period began about 12,000 years ago – when our ancestors were presumably living in caves and dressing in Mammoth pelts. To say nothing of our non-contribution to the previous 4 interglacial, which seemed to get on with it without our help, or even presence, at all.
If growing CO2 concentrations in the atmosphere depended on human activity, then what caused those previous spikes, corresponding to when things got warmer, ice melted, and forests grew in Greenland? The only rational, scientific, evident based conclusion is that something other than human activity is responsible for virtually all the CO2 build-up in the atmosphere over the last 10,000 years, just as something other than human activity was responsible for the previous build-ups, when there were few if any humans around. Now, if the spike were, say, twice as high as all previous spikes, then we’d need to search for a new, or at least different, cause. But since it looks to be in line with every other previous spike for which we have any real evidence – well, there is no reason to suppose a new and different cause for something that is neither new nor different.
Are the ice sheets and sea ice melting in the Arctic, Greenland and Antarctica? Are glaciers retreating? OF COURSE! And, one might add: thank God! Because – follow this closely – once they stop melting, this interglacial period we’ve been enjoying for the last 10,000 years or so is almost sure to be over. And whatever horrors we imagine might happen from global warming, they pale when compared to a return to glaciation. However unpleasant having coastal areas flooded and agriculture disrupted, those things are not nearly as unpleasant as having Canada, the upper Mid-West, Scandinavia, most of England, Northern Europe and parts of Russia buried under a couple miles of ice. Disruption doesn’t begin to describe what that would be like.
Since some or all of the Greenland ice sheet disappeared during the last interglacial 125,000 years ago, it should hardly be surprising if it’s melting now. Same goes for the West Antarctic ice sheet – on what basis should we expect it to stay the same? It’s been around for half a million years or more – we’ve been seriously studying it for maybe 75 years? We don’t have satellite data for the tens or hundreds of thousands of years we’d need to establish a baseline against which to compare the last couple decades. So, scientists are sure we’ve past the point of no return, and, in a worse-case scenario, global sea level will rise 10 feet over the next 200 years. That’s 0.6 inches a year. More practically, low-lying coastal areas have 8 – 10 generations in which to move to 10′ higher ground or build some dikes – worst case. The most pessimistic non-fear-mongering estimates for how long it would take the Greenland ice sheets to melt and raise sea levels 20 feet is around 2,000 years. So, worst case, we have 8-10 generations within which to move our low-lying coastal settlements far enough inland to accommodate 12′ higher sea levels.
This is certainly something to be aware of, but hardly something to panic over. How many cities are more than 200 years old? Within 200 years, we’ll need to rebuild 90% of the buildings in any event – how about we rebuild them further inland?
This leads into a bigger problem: since climate is weather over time, one must establish, at least tentatively, somehow, how much time is enough time. In other words, just over the 2,000 or so years for which we have human records, the climate has fluctuated. We don’t even remotely understand why – we’ve got a few ideas, but hardly a good solid testable theory. Those ice cores mentioned above suggest it fluctuated a heck of a lot more over half a million years. Geological evidence suggests that even the ice ages are themselves fluctuations – the earth has been (probably) an ice ball for hundreds of millions of years; for other millions of years the seas around the equator seem to have been too hot to support macroscopic life. How big a time frame would we need to understand in order to sufficiently model the factors that create climate enough to make confident predictions? A million years is probably not enough; a century and a half is laughable; 50 years would be a joke, even if the predictions for the last 2 decades had been correct. That’s just not enough time to get a grip on forces that act over thousands and millions of years – which, given the kinds of long-term cycles we actually have physical evidence for, is the range we’re talking about.
It’s a truism that weather forecasting converges with Almanac-level general trends any more than three days out. In other words, if you substituted ‘it will be spring’ for days 6 – 10 in a current 10 day forecast, you’d get as close, generally, as those advance-degree-awarded, satellite and radar deploying meteorologists. Not to knock what those people do, but rather point out how hard it is. Climate forecasting is even harder. The only reason anyone should ever believe a climate model is if predictions made using it come true. Specific, measurable predictions.
Conclusion: I’m not denying anything for which there is any evidence. (Note: model output is not data. Repeat that to yourself as often as is necessary to free yourself from that stupefying, superstitious delusion.) What I’m denying, if I’m denying anything at all, is the sense of doom and panic that is wildly out of proportion to the actual evidence. As I’ve said before, I’d much rather we spend our time and money installing state-of-the-art sewage and industrial waste treatment facilities everywhere on the planet, and then studying the ocean until we know what’s there, what it does, and how we can keep it nice for ourselves and our descendants. Because, after all, if we’re not taking care of the biosphere to keep it nice for ourselves and our children, why would we care at all?