In my last post on natural law, I focused on how changing minor “precepts” might make tremendous impacts on our theological understandings. I used cosmological models from general relativity to illustrate the point.
Today, I want to look at things a little less, well, cosmically, and review how changing scientific “precepts” over the last few years also limit our ability to predict the outcome of policy decisions we make as a society today — even though we know those policy decisions are likely to have profound moral consequences.
In her post last week, Tatiana made the valid point about the necessity of thinking way ahead about long range problems having major impacts in order to avert them. That would certainly be a good idea. “Could’a, would’a, should’a” is already an applicable response to many of the problems we see today. However, we have to remember that what we actually did in the past seemed like good ideas for solving the problems we had to solve at the time. I suspect “judge not lest ye be judged” would work quite well even if it were merely a subtle scriptural reminder that most of us will have great-grandchildren who will wonder how we could have been so stupid. So this discussion is really a follow-up building on her post as well as my earlier post.
I want to illustrate one aspect of our dilemma in trying to carry out long term planning by talking about climate change, and what science can offer as a guide toward the policy discussion today as opposed to what we thought perhaps five years ago.
Here it is useful to consider what we know about the happenings at the end of the last Ice Age. About 20,000 years ago, Canada, the Northern United States, Scandinavia, and Siberia were mostly buried under thousands of feet of hard ice — enough to lower world wide sea level about 400 feet, connect Eurasia with the Americas by land and generally make the shape of the continents fairly unrecognizable. This Ice Age was one of several that have been occurring with a cyclic regularity (due to perturbations in earth’s orbit and orientation to the sun caused by pulls from other solar system bodies) since geological processes themselves raised the coast of Central America above the waves about 3 million years ago.
And so each cycle has an ending, too; things start to warm up when the glaciers are stretched to capacity, and summer sunlight in the northern hemisphere then starts to increase.
The ice starts to melt, and the melt water has to find its way back to refill the oceans somehow. And this has some counter-intuitive effects because the melt water is fresh and the oceans are salty. Salinity, it turns out, has had a vital role in driving the ocean currents, and, thus, the climate, at least since the uplift of Central America I mentioned above finally sealed off the most equatorial route for currents to flow between the Atlantic and Pacific Basins through Panama.
The relatively high salinity of surface ocean waters (due to evaporation) compared to deep ocean water makes them less dense, allowing them to carry heat farther north through currents such as the Gulf Stream. It is that heat which keeps Western Europe, in particular, relatively warm in modern times. Thus, if anything lowers the salinity of the northern waters so that they become more dense while farther south, the sinking becomes more diffuse, the Gulf Stream becomes less intense, and, in fact, ocean circulation as a whole slows down because there is no need for cold deep water to rise toward the equator or in the southern oceans to become the replacement source water of the Gulf Stream.
And the best way to mess up the salinity of the Gulf Stream is to dump lots and lots of fresh water into it from the melting ice sheets. Oh, but then, Europe and North America, having lost their Gulf Stream blanket, will turn icy again, and that should stop the melting.
And, that’s what we see in the record of the Northern continents. Almost as soon as the melting started, the North was plunged back into a “dryas”, a resurgence of the ice that lasted more than a thousand years. And this is where the puzzle really got interesting, because the melting/dryas minicycle has no obvious exit ramp. Canadian ice hockey, at least, should be played under the ice rather than on top of it. So what leads to a complete end of the Ice Age and a full “interglacial” period like modern times?
As outlined in New Scientist a few weeks ago, the Northern and Southern Hemispheres began to behave in opposite manners when the dryas began. The North went back into the freezer, but the South just kept getting warmer, even though there was no real link observable in southern summer sunshine. The conventional wisdom is now that carbon dioxide rose and warmed the south — a rise that postdated, not preceded the initial melting, and is clearly visible in what data records we can obtain from the time — but the rise in carbon dioxide was attributable to a natural process larger in scale than the Thermohaline Circulation’s effects on climate in the North, i. e., the one causing the dryas. With the northern circulation suppressed, the ocean and wind currents in the Southern Hemisphere spontaneously reorganized — we still do not know in exactly what way — to produce a closed, more localized circulation there that brought much more upwelling of deep water filled with carbon dioxide to the edges of Antarctica. The lower pressures of the surface water allowed the carbon dioxide to escape into the atmosphere, where its greenhouse effect began to do a number on the southern polar ice cap. The earth “see-sawed” through thousands of years of dryas and non-dryas circulation states, but each time seeing less ice, and higher carbon dioxide and sea levels overall. (And at various times in there, you get catastrophic floods in various places like the Persian Gulf, the Black Sea, and Southeast Asia, too, which get passed down to moderns as stories of world-wide deluges.)
On its own, the cyclic change in northern sunshine is likely to lead to a slow cooling, but nothing like a return to the ice age for tens of thousands of years. But of course, the climate is no longer on its own. Humans are dumping carbon dioxide into (especially the Northern Hemisphere of) the atmosphere at geologically unprecedented rates and much of the northern sea ice is already melting. Our best models say we are going to get unprecedented climate impacts accordingly.
However, as the “new” conventional wisdom about the historical collapse of the last ice age shows, the models are highly uncertain and subject to constant revision when it comes to understanding regional impacts — and it is regional impacts that determine what people have to plan to mitigate. After all, we’ve seen that it is apparently possible to have great warming and great cooling simultaneously, and we’ve not explored all the possible states of spontaneous reorganization the oceans and atmosphere may assume.
For example, the “old” conventional wisdom held that the bulk of the North American melting that triggered one dryas 13,000 years ago entered the North Atlantic through the St. Lawrence from ancestral Great Lakes. Yet models now suggest that would put the fresh water too far south to have produced the circulation slowing of the Gulf Stream. Instead, there are now suggestions that the catastrophic draining came on the northwestern edge of North America, directly into the Arctic Ocean by way of the MacKenzie River and then flowing across that Ocean into the North Atlantic east of Greenland. The two scenarios produce very different climate impacts around the Arctic Basin, with their own potential for unexpected feedbacks elsewhere.
“Uncertain” is not the same as “wrong”. An inability to predict what we need to predict to mitigate the climate problems doesn’t mean there’s no climate problems. (Think of the stereotypical “snake oil salesman” of the Old West. The fraud was in claiming the snake oil would cure anything; the fraud was not in claiming that people needed a cure.) And here, even if the models are correct, they point clearly to the fraud. As I wrote here more than three years ago, we can impose limits on greenhouse gas emissions to levels that we haven’t seen since the later nineteenth century, with all of the economic and social disruption that would impose, and still achieve nothing but a delay of about two years from exceeding a temperature change (+2 degrees Kelvin) that international scientific bodies have deemed unsafe. At this point, it seems that the response of the economic and geopolitical systems to the change in the environment is more critical than the environmental change. Environmental change seems pretty locked in at this point.
Physical law usually makes no exceptions for good intentions or listens to our votes. If we model the behavior of the atmosphere incorrectly, and nature gives us a mini ice age when our best guess was for the tropics to spread north (or the other way around), our flood protection measures are uselessly built inland, we plant crops in the wrong places, and we don’t get our lost economic growth back. Without that growth, if we then model human behavior incorrectly and adjust our military and entitlement resources accordingly, being sorry will be insufficient when our defense or entitlement systems break down. If we impute intent or capacity to individuals in power here or abroad, and we are wrong about them, the “people suffer”. For that suffering to happen, our leaders don’t have to be “wicked” (although being snake oil salesmen won’t exactly help); they just have to be wrong.
Thus, as desirable as it is (and I do acknowledge the desirability) to plan for the future, I tend to see success at that sort of planning function requiring more than human abilities and time scales. Indeed, I feel a little like the field mouse in the famous Robert Burns poem who labors mightily to build a better nest, only to have the farmer sweep in and mow the field because the farmer has a different purpose.
But little Mouse, you are not alone,
In proving foresight may be vain:
The best laid schemes of mice and men
Go often awry,
And leave us nothing but grief and pain,
For promised joy!
This isn’t even about the distinctive views that progressives and conservatives hold about what moral values should be; this is about the inability to identify choices correctly that will produce those moral outcomes. The Universe (and/or its God) will do what it intends to do, regardless of whether we take a clue about what that is or not. The Farmer outranks the mouse, and mice that prosper are the ones who evolve a balance of behaviors in case some of them get the intentions of the Farmer wrong.
Do not put too much faith in the stability of your nest, little mouse.