Each era has its own dominating themes of global politics. The 19th century had the politics of industrialization and empire. The first half of the 20th century bowed to world wars and economic depression. The second half was overshadowed by the cold war. Our era, I believe, will be dominated by the geopolitics of sustainability.

Economic development has become a generalized global phenomenon, except in sub-Saharan Africa and a few other poverty hot spots. Even those impoverished areas will probably achieve economic takeoff with a little international help and the application of "best option" technologies. The world's total economic throughput every year, adjusted for differences in countries' purchasing power and measured as the gross world product (GWP), now stands at approximately $60 trillion. Over the past century, the GWP has grown roughly 18-fold in price-adjusted terms.

With that increase in economic output have come some phenomenal benefits, such as rising life expectancy and improved overall public health, and some planet-threatening adverse effects, such as massive tropical deforestation, ocean fisheries depletion, man-made climate change, violent competition over limited hydrocarbon resources, and newly emerging diseases such as SARS and avian flu (H5N1). Until now, the favorable outcomes have outweighed the bad. Yet because many of the environmental consequences are hidden from view and from our national income accounts, we sit atop ticking ecological time bombs.

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