Most climate change forecasts focus on the period of crisis that will occur over the next 90 years, dropping off at that arbitrary endpoint, the year 2100. Partly, this arises out of the lack of solid data. After all, we can forecast the climate using elaborate climate models, but attempting to forecast how human beings will respond to those changes exceeds the powers of the most complex modeling software available. And the choices humans make will have enormous influence over where we stand in 2100. So, the answer to what happens after the period of crisis will remain a mystery until events unfold and it becomes obvious.

Still, we can speculate with one eye on the climate models and another on the historical record.

To begin, let’s start with the future history, 2010-2100. As the title of this blog would indicate, the working hypothesis is that the likely scenario is a worst case scenario, where climate change occurs within the bounds of the more pessimistic climate forecasts. The argument for this is that, historically, the more we have learned about the climate system, the more likely the worst case scenario has become. For example, the IPCC has repeatedly been forced to update its conservative consensus reports over the years as our understanding of the climate system have advanced (More on that here). My own personal view is that we are hard-wired to view the Earth as a slow-moving, sturdy system that we cannot possibly alter in the span of our own lifetimes. But, scientists are discovering that feedback loops can shift us into spiraling, runaway warming. In last week’s blog, I wrote about the discovery of just such a feedback loop which may have been triggered in the Arctic.

For climate change wonks, the scenario this blog anticipates is something in the range of the A1 or A2 IPCC scenarios. The A1 family of scenarios are ones of rapid economic growth in an integrated world economy with rapid technological change and a global population of 9 billion by 2050. Some A1 scenarios expect efficient technologies to become available and widespread (A1B and A1T) while others see continued reliance on fossil fuels (A1FI). In the A2 scenarios, the world is less integrated and more regional, with mixed economic growth and slower, uneven development of new technologies. Given recent economic and political events, I’m increasingly siding with the A2 scenarios, so for simplicity, I’ll use that one in this post.

So, in our A2 scenario, we have the emergence of regional powers, the US, China, Russia, Brazil, Europe and perhaps India, with integration limited by political conflict over dwindling energy, water and food resources (see my series on the economic crises global warming is expected to unleash). In between these economic centers will be collapsing smaller economies as global warming begins to undermine the integrity of poor nations, similar to what has already happened in Somalia and Darfur.

An abbreviated chronology of climate events shaping our future history would include:

• 2030s Dust bowl-like collapse of the American Southwest due to persistent drought; weather-related disasters will up by 300%
• 2040s The world warms beyond the critical 2ºC “safe” limit; glacier-based water resources begin to fail in China and India; the Arctic Sea is now ice-free in the summer, reducing Earth’s albedo and exacerbating global warming
• 2060s Amazon rainforest begins to die, the soil-based carbon sink begins to collapse
• 2070s The world warms beyond 4ºC above pre-industrial levels, with the Arctic warming by 15ºC or more; The power of vegetative soil carbon sinks begin to weaken
• 2090s Annual precipitation decreased by 20% or more in key agricultural regions, and increases 20% or more in other areas
• 2100 The world approaches the 6ºC mark; 10-20 feet of sea level rise

In addition to the events listed above, are some that we cannot be so sure of, such as whether or not the warming will trigger other disasters or feedback loops, such as the melting of Greenland ice to such an extent that it dilutes the salt-driven Gulf Stream that keeps Europe and the Northeastern US warm; or acidification of the ocean, causing massive extinctions of the fish humans depend on for protein (20% of our protein comes from fish). Also, we do not know yet what affect the recently discovered methane leaks in the Arctic will mean for global warming, but it could make the above chronology look naively optimistic.

But what is clear is that our entire global order will not respond well to those changes that our models already forecast. As I argued in my economic series, the world economy will be sent into a downward spiral as we both reach the limits of our planet’s carrying capacity and reduce that carrying capacity through global warming even more. On the water issue alone, I worry that we are setting ourselves up for a regional nuclear war (such as between China and Russia, India and China or India and Pakistan) as chaos and desperation turn normal diplomatic protocol on its head. For those that doubt that people are willing to wage nuclear war over water, it is important to note that the standoff between India and Pakistan in Kashmir nearly turned into a nuclear war in 2001 (Pakistan considers Kashmir a strategic interest since it is the source of the bulk of that nation’s water).

We know that even a limited nuclear war, like that which India and Pakistan nearly waged would blast sufficient smoke and dust into the upper atmosphere that global crop production would crash. In their study of the after-effects of such a small nuclear exchange, Alan Robock of Rutgers University and Owen Brian Toon of the University of Colorado, found that 1 billion people would likely starve as this soot lingered in the upper atmosphere, reducing sunlight and even rainfall. Additionally, they determined that terrible damage would be done to the Earth’s ozone layer, causing long-term damage to plants, animals and people.

But even if wars over scarce water do not lead to nuclear war, a simple mapping of our above timeline to actual nations suggests a very destabilizing future ahead. First of all, populations will be on the move and in huge numbers. Extreme drought conditions in the Southwestern US, Mexico and Central America will mean that millions of people will be forced to find new places to live as they flee regional economic collapse. Americans already experienced such an internal dislocation during the Dust Bowl years of the 1930s, which led to widespread social unrest and injustices. Today, there is also tension with economic refugees from Latin America which have migrated into the US, often despite efforts to stop them.

Mass migration will not only be a problem in North America, but can also be expected in Europe, China, India, Brazil and throughout the Third World. In other words, the entire human diaspora will be on the march…or enlisted to resist that march.

And this at the very time that the world economy begins to suffer from the adverse affects of climate change. For more, see my series on this topic.

Assuming that humans can survive war, and economic collapse, what then? Moving beyond 2100, the IPCC tells us that sea-level rise will continue for 1,000 years no matter what we do, so the next millennium of human history will likely be shaped by ever-changing coastlines. This is important because one third of the people on Earth live within 50 miles of the sea. Moreover, we can expect changes to the weather to also continue for a thousand years. This is because it takes that long for warmer temperatures in the atmosphere to penetrate the deep ocean. And since those currents shape our weather patterns and regional climates, there is no telling what kind of planet we will have centuries from now.

We do know that the Arctic will warm far faster than the rest of the world, with a 15% or more increase in average temperature by 2090. It is also forecast that precipitation at the poles will skyrocket. In other words, the northern latitudes, and perhaps, someday Antarctica, will begin to show promise as new sites for human settlement. Of course, there are problems with the idea that humans might just transplant our civilization more or less intact to these places. One primary issue is that the closer one moves to the poles, the less solar radiation that falls on the land, impacting plant growth and thus hopes that we could grow as much food in, say, northern Canada as the United States currently does today.

Still, as the Arctic ice recedes, boomtowns will surely spring up. This is already happening in some places in Norway as investors and governments begin eying the implications of ice-free sea lanes in the Arctic Sea.

Yet, reconstituting a polar humanity is really an optimistic scenario. Before we lay down the foundations of a civilization that can live in a hot world, we must first pass through the fires of this century. By mid-century, we are expected to have 9 billion mouths to feed, with an unprecedented number of them expecting first-world helpings. If nothing else frightens you, it should be that image. The Earth is already overburdened, with agriculture falling short year after year to keep up with demand. Add to this picture a dislodged climate and you can see why an orderly move toward the poles may not happen. In brief, the Global Humanitarian Forum has estimated that a billion people will die this century as we overshoot the planet’s carrying capacity. And I would add, those billion people will not go quietly.

Indeed, as Jared Diamond has shown in his work on historical collapses, when faced with disaster, humans have often worked counter to their own long-term, collective interests. He offers many examples. As the climate shifted into a cooler period in Viking Greenland, the remaining Viking settlements that still clung on were eventually overrun by their starving neighbors, leading to a total collapse of that society. On Easter Island, the same civilization that had built the Moai statues slid into barbarism that resulted in the almost total extinction of the human population there. Rather than coalesce around survival strategies that could heal their depleted island ecosystem, warring tribes struggled for control of the last resources. The end result was a much reduced population living in caves, inheriting a treeless island with no memory of why the Moai were built in the first place.

And so, it is clearly difficult to forecast the long-term human tragectory. Not only is it difficult to calculate how we will react, but it is rather uncomfortable to even contemplate the likely scenario.