Tuesday, 22 March 2011

Scenario planning for climate change

The science of climate change is good enough to show that global temperatures will rise unless we cut back drastically on greenhouse gas emissions. What no science can do is show whether we will do so – or what policies nations will adopt if we do – or if we don’t. Nor can we predict the human – health, nutritional, political and economic – consequences of rising temperatures. Yet these are what people care about.

We badly need ways of thinking about the implications of climate change. Most of what’s written gets hung up on the uncertainties of the science. If we don’t know, and we don’t, whether temperatures will increase by two or four or six degrees how can we prepare?

The answer is scenario planning.

In scenario planning, a method pioneered by Shell, we focus on the uncertainties, not on forecasts, and use these to define a set of possible scenarios. If we get this right the actual events will follow one scenario or, more likely, fall between several scenarios. But in any case we’ll have considered what we can and should do before we have to do it.

Climate change is a long-term problem so let’s look at the long-term – 2030 and beyond On that timescale little is certain but there are two big uncertainties.

The first uncertainty is the temperature increase. The global temperature is currently 0.6 degrees higher than that in the pre-industrial period. By 2030 we ought to know whether we’ve managed to keep the increase below two degrees. That’s hardly risk-free but it should be manageable. If we haven’t then we’ll already be aware of the positive feedback effects that will drive the temperature to a four or even six degree increase. (Some models suggest that rises over ten degrees are possible but let’s not go overboard; four degrees is bad enough.) (The environmental consequences of various possible temperatures have been discussed by Mark Lynas in Six degrees. Prof. James Lovelock has discussed the positive feedback effects in The Revenge of Gaia.)

The second uncertainty is the degree of international collaboration on dealing with climate change. The Montreal treaty on CFCs showed that international collaboration is possible. The post-Kyoto experience shows that it’s very hard to get when it requires significant economic sacrifice. However, even politicians and civil servants can learn from experience and worsening climate will provide many powerful lessons. The real uncertainty is whether governments will commit to enough change soon enough to avoid triggering the positive feedbacks.

Now we combine the two to get our four scenarios as shown in the figure. I ignore the possibility that we can keep the temperature increase below two degrees without international collaboration because it’s impossible (unless the scientific consensus is badly wrong).

There are two scenarios for a world without catastrophic climate change. In the Lifeboat scenario this is achieved by international collaboration. In the Emergency Braking scenario collaboration fails and its achieved by unilateral action, mainly geo-engineering, by a major power.

There are also two scenarios that do involve catastrophic climate change. In the Police World scenario the nations collaborate to manage the consequences whilst in the New Dark Age scenario they don’t.


I’m aware that two, perhaps three, of my scenarios may sound more like science fiction than sober reflection. However, these scenarios run forward from 2030 and much of today’s world would have seemed like science fiction to our parents. It’s almost impossible to overstate the impacts of four degrees of warming. It’s inconceivable, at least to me, that our civilization will be unchanged by these impacts and it’s time we took this seriously.

Friday, 18 March 2011

Scenario 4: The New Dark Age

In the final scenario attempts at international collaboration have failed to prevent temperature rises and have broken down. As temperatures rise nations and subnational groups will fight for survival destroying civilisation and creating a new dark age.

Change will have become irrevocable and some previously fertile land will have gone out of use. Food shortages will be normal and famines common. During famines there will generally not be enough spare food available from outside the stricken area to feed the hungry making starvation common.

Institutions and individuals will generally have recognized that long-term survival with any degree of security and comfort will be possible only in places remote from the equator. Only in these places will the impending climate catastrophe leave land for agriculture.

Since the majority of countries are not remote from the equator their governments will attempt to negotiate access to places that are. Countries that do include high latitude regions will recognize their value and will generally be unwilling to provide access; preferring to keep them for their own inhabitants. They will increase military expenditure and strengthen their defences.

As temperatures rise food shortages will increase and people will migrate away from the equator and the lowlands. Conflicts will arise as the migrating populations press upon national boundaries or encroach on lands previously used by other ethnic groups within the same countries. Darfur may be seen as an early example of such a conflict. These conflicts will arise even where the disputed land provides no long-term security. If faced with the choice between violence and starvation those not actually starving will choose violence.

Some large nations, the USA and Argentina for instance, will include some refuge areas though not enough for their whole populations. Civil wars will result in these nations. In some cases these wars will be encouraged by neighboring nations who hope to grab some of the more attractive land.

These conflicts will often be exacerbated by religious and ethnic differences and recollections of past grievances, actual or supposed. These differences and grievances will be emphasised and exaggerated, and sometimes invented, by unscrupulous opportunistic politicians. (These processes could be seen operating in Rwanda and Yugoslavia.)

Detailed predictions of these conflicts is impossible but with stakes so high – both national survival and the physical survival of whole populations – there is no reason to expect much restraint. Nuclear, chemical and biological weapons will be used.

Repeated wars will inflict major damage on the very resources, both agricultural and industrial, that they are trying to control. Continued warfare will also destroy much of humanity’s capacity to innovate, except in military matters, and to do or even understand science and the arts.

As climate pressures increase (over a period of many decades) military power will become the dominant reality in human affairs. Political authority will give way to it. Jared Diamond’s Collapse gives examples of this breakdown.

A new global Dark Age will follow in which most of the survivors will live in militarised refuge areas in high latitudes. Food will be scarce and almost all resources will be devoted to survival – water supply, food production and defence. Commitment to survival goals will be enforced by the authorities and underwritten by new religious ideologies. Dissent will not be tolerated and punishments will be both severe and quick.

Survival outside these refuges will be limited to hunter-gatherer bands and small agricultural villages. As between them, suspicion and violence will be the norm.

After the Dark Age
The new Dark Age will doubtless last several centuries, during which the human population will fall to a fraction of its current level. The best that can be said of this scenario is that it need not last indefinitely. Neither the Greek nor the later European Dark Ages lasted for ever. Each ended and was followed by a notable period of cultural flowering – the Athenian Golden Age and The European Renaissance.

Though we have not previously experienced either a global Dark Age or such abrupt climate change there is reason to hope that our descendants will ultimately be able to rebuild civilization.