This continues my series on climate change as I go on reading the IPCC 2013 Technical Report, and some divagations about it.
This divagation is of considerable importance...
As most of you know, sea level is changing. Actually, it's increasing: not dramatically fast, just a matter of millimeters per years (to date), but projections let us imagine this rate will rise.
Anyway, it is not the increase rate to give me worry: it's the cumulative effect.
Can this phenomenon be realistically altered in the next future? Experts say "no". There is some difference among the models on which projections are based on, but all them suggest we should better not expect a decrease in the next future, even if severe measures are taken. That these measures are urgently needed is not me to say: adopting them or not will make the difference between the less and the most dangerous changes.
But something "will" happen. It's very much better we envision something in advance.
The cause of sea level increase is well known: continental ice shelves are reducing. The molten ice, now water, runs to the sea at a speed higher than evaporation can compensate, even under temperature rise. So, the amount of water in the oceans increases, salinity diminishes a little bit, and level rises.
As we all remember, this year for the first time two experimental routes have been opened north of Russia and America. That's maybe good for international commerce, but highlights in the saddest manner a fact: the Arctic oceanic ice shelf is melting very quickly - and there is no need to read in depth the IPCC report to realize this. Arctic ice shelf is relatively shallow however, and (perhaps more important) it is in buoyancy equilibrium with liquid water: its melting will not alter significantly mean sea level (it will have other consequences on salinity, and change of the amount of solar radiation reflected back to space. But no sea level troubles...
What's really worrying scientists are two other places in the World where most continental ice shelves concentrate: Greenland and Anctarctica. A massive melting of ice there will cause a direct inflow to ocean, and in this case the sea level will increase.
Two years ago I had the lucky occasion to have an interview with a friend who is a climatologist, volunteering every year for Dome Concordia base in Anctarctica. He told me the worst case was (was) Greenland, where a voluminous thickness decrease in the ice cover has been detected. This in part was due to slight changes in oceanic currents which are occurring slowly. The huge effect of even small changes in oceanic currents in the Northern Atlantic is largely due to the fact the Gulf Stream transports immense amounts of heat from the Gulf of Mexico to Western Europe; this amount is so large to make a continent mostly above 40 °N of latitude inhabitable thanks to its mild climate. Would a little part of this heat go where it should not, Greenland, would greatly accelerate the loss of ice shelf.
In comparison, he also told me, the situation of Anctarctica was (was) slightly better. Because of the way continents are placed, from Anctarctica coast line to the southernmost edges of Africa and America there is a huge space entirely covered by ocean. Water may run freely along the parallels, and the resulting cold current around Anctarctica tended to act as a sort of protection: ice shelf decrease has been observed there, but a rate much smaller than Greenland.
If I remember my friend's figures, a complete melting of Anctarctic shelf would cause a sea level increase in the order of 70m. That would be a global catastrophe, to which the current world civilization would hardly survive. But, may be this not extremely likely to occur in future? Sure, such a catastrophic effect is projected so far away that we humans have some time to undertake mitigation measures.
With Greenland, the story is quite different. In case its shelf will melt completely, the sea level will change much less spectacularly, in the order of 7m. But this might happen in the short term.
I'm quite afraid, we have a problem - and an urgent one.
7m of sea level increase is an enormous amount. It would mean, to mention just a famous case, that the MOSE system in building to save Venezia from "high waters" will be overrun by 7m. The "Laguna" of Venezia is too large for protecting using, say, a future super-MOSE. Maybe, a solution like the polders in Holland (using dams towards the sea) could work - if only there is time to act.
That of Venezia is quite spectacular a case. But is just the tip of the iceberg (no pun intent)-
In fact, most towns (and by definition all ports and harbours, are now close to sea level, and an increase of it would cause enormous damage.
Which damage actually, is largely matter of speculation. Some effects are quite obvious, so much that even I can imagine: a significant part of building (residential, religious, productive and storage) will be flooded as the coastline regresses. In few days they will be useless - and within a few years tidal erosion will have cancelled most of them. All people living or working there will have to move somewhere else, having lost everything and having little way to arrange without help for their future.
Another obvious effect will be that the water table will change. Salt water will progressively invade it, as the new coastline will move towards the inner part of the towns. This will pollute many pits of drinkable water. Along with the new allocation of population, this will give an enormous pressure on existing and still working pits, exacerbating possible conditions of scarcity.
Salt water may also trigger chemical reactions damaging foundations of buildings located well inside the new, retreated coastline.
But the real danger is, we do not know which all the consequences will actually be. My guess is, things will happen in a very "specific and contextual" way. Each coastal city has its own vulnerabilities. Because of this, a standard, one-for-all policy will be unlikely to result in some success.
Analyzing these vulnerabilities, and predicting the effects of any specified sea level change between 0 and 7m is possible, by combining a variety of techniques.
One of these is mapping as precisely as possible the towns from the level 0m (current coastline) and, say, 50m above actual mean sea level. This mapping should likely include the terrain topography (this is the simple part: satellites orbiting around the Earth know this information exactly; although not up-to-date (it precedes the December Tsunami) there is even a widely diffused data set collected during one Space Shuttle mission - see "SRTM" for reference). It should also include buildings (all of them!) and any "technological network": gas pipes, electric power and telephone lines, underground railways and passages...
The difficulty is immense, but not impossible. And, there is some time.
Once this knowledge is available, a "strategic retreat plan" will have to be devised. In my feeling it will be of highly "contingent" nature (if the sea level changes 1m, then do this; at the next 1m do that; and so on". But it must be defined.
This planning (and the crude, unpopular decisions it will inevitably imply) is not a task for scientist: politicians will have to. Of course, they will have to accept the "danger" of not being re-elected, at best. But this is a thing to do, and theirs is the final responsibility.
I didn't mention a fact which will give the operation even less a popular face: in preparation to the strategic retreat, an immense amount of money and resources need to be saved. In face of this "problem", any pretence of "light state" and tax reduction is, let me say, complete rubbish. Don't save, and no action will be possible. No action made, and a mass of ferociously angry homeless people will flow to the still inhabited part of towns, with likely complete social order destruction.
I feel my writing lacks of clarity, in giving the impression the "battle" is in course and, given favourable circumstances, be won. The hard truth is we have already lost it, and there is very little we can do to save the (relatively "small") shelf of Greenland.
On the other side: an old Prussian piece of wisdom says that the difference between a strategic retreat and a complete defaite is that the first is planned. Planning a retreat, even the most orderly one, typically yields very little reward, so I'm sorry for today's politicians who will presumably pass their names to History as enormous losers. But much better a loser, than a criminal against humanity.
Prussian pieces of wisdom, it may be said, may be of limited general value. And I feel this exactly is: conceptualizing the danger our civilization is facing as a "battle" instead of what it really is, a natural phenomenon (helped a great deal by our species blind misuse of natural resources) is highly limiting. If this is a "battle", than we can't see an "enemy" - only its "weapon", as a mass of salt water. Changing from "battle" to "evolution" paradigm, however, might not be so simple in the short span. Simply, the scientific community has not accumulated enough data to formulate veritable "predictions" instead of "projections". So, we may provisionally adopt the ugly "battle" paradigm - and continue to evolve knowledge until a perspective shift will be possible.
Building the plan I mentioned demands an active decision by politicians, But also a lot of work: field surveys, risk analyses, hazard and operability analyses, failure mode and effects criticality analyses, building and use of Geographical Information Systems, data analysis, engineering and economic reassessments... If politicians may be illuding themselves these tasks will be on grasp of their small group of faithful technicians-supporters, it is the task of us citizens to force them stay with their feet well rooted on the ground. And forget fidelity: there will not be any chance for re-election, given their task. So, they can well afford hiring competent people with diverse background and views.
Of course, all what I've said needs critical evaluation and discussion.
But you may check yourself whether all of this is "rubbish", or not. With a clear awareness the problem is of strategical and political, not "scientific" nature.
Love, hope - and Prussian-style determination.