Understanding a warmer world.

As reported widely in various media outlets, the U.S. Department of Energy recently calculated that, in 2010, global emissions of carbon dioxide rose by the largest amount on record, and are now higher than the worst-case projections envisioned by the Intergovernmental Panel on Climate Change four years ago. Meanwhile, the prospects for technical solutions seem more dubious than ever, even those as seemingly straightforward as whitening our cities. The need for immediate action to lower global greenhouse emissions and limit future warming to 2 degrees Celsius is more urgent than ever, but the chances for any kind of comprehensive or effective deal to emerge from this month's climate summit in Durban, South Africa are dismal at best.  

In the West, popular alarm over the prospect of global warming has been diluted by years of skepticism driven by free market fundamentalists, funded by industries that have too much to lose. Worse, the western financial crisis, stimulated by hyper-capitalist practices similar to those that threaten the world's environment, has placed climate change legislation on the political back burner. In America, the world's second-largest producer of carbon, the prospect of a climate change "skeptic" winning the White House in 2012 is a very real possibility. 

Many regimes in developing nations - of which China is the most important - draw a similar link between carbon production and economic growth, reasoning that it is unfair to ask burgeoning economies to abort their own growth by compensating for the excesses of the west. In fact, at Durban the BASIC group - Brazil, South Africa, India and China - will argue that in the first half of the century the developed world should absorb from 239 to 474 billion tons of carbon dioxide as developing countries continue to pollute. In the long run it is likely that any prospects for an effective climate settlement limiting warming to a "reasonable" level will be torn apart in the vortex of changing economic relationships and continuing mistrust between east and west. 

Earth's climate, then, will almost certainly get much warmer. How much warmer is, of course, uncertain. Who can say how environmental changes outside of anthropogenic global warming will interact with unpredictable, perhaps unimaginable political or cultural developments over the coming century? However, the best projections currently available chart a rise in global temperature of at least 4 degrees celsius by 2100, an increase that could fundamentally alter the geography and biology of the planet. In many respects the crisis could hasten its own solution, as modern humanity,  its gigantic population so dependent on western monocultures and capitalist structures, must either change dramatically or face a truly unprecedented demographic disaster.

The looming, seemingly unavoidable catastrophe on our horizon prompts a very simple question: can we look into the past for answers? If what's to come is so unprecedented, is history any use? Unlike scholars in other disciplines, historians are always reticent to say that the past is any guide to the future. How can it be when every variable changes throughout time, obscuring any superficial similarity between historical events and present challenges? Historical climatologists might study the Medieval Warm Period and catalogue its influence in the course of human history, but can studies exploring a 1 degree Celsius rise in global temperature 800 years in the past have any relevance for our understanding of global warming? 

In an era when many historians have chosen to be "active" - to engage the present context for their historical interests - the answer is as clear as the question. History is an imperfect guide to the future, historical research can benefit from abstraction, but historical climatology can still provide us with one of the deepest and most sophisticated visions of the relationship between climate, local environments, and humanity. In a warming world, few pursuits are more worthwhile.