Never say never. Because of the economic crisis, habits that seemed unalterable are suddenly being altered. Americans are now saving more and consuming less. Financial institutions are no longer betting the house on risky investments they do not understand. Many wealthy oil-exporting countries are tightening their belts. Everywhere, change is in the air.

Everywhere, that is, except in the way humanity responds to its most menacing threats. You know the list: climate change, nuclear proliferation, terrorism, pandemics and trade protectionism. Not one can be solved, or even effectively contained, without more successful international collaboration. That is not happening.

Indeed, when was the last time you heard that a large number of countries agreed to a major international accord on a pressing issue? Not in more than a decade. The last successful multilateral trade agreement was in 1994, when 123 countries gathered to negotiate the creation of the World Trade Organisation and agreed on a new set of rules for international trade. Since then, all other attempts to reach a global trade deal have crashed. The same is true with multilateral efforts to curb nuclear proliferation; the last significant agreement was in 1995, when 185 countries agreed to extend an existing nonproliferation treaty. In the past 15 years, moreover, India, Pakistan and North Korea have demonstrated their certain status as nuclear powers. On the environment, the Kyoto Protocol, a global deal aimed at reducing greenhouse gas emissions, has been ratified by 184 countries since it was adopted in 1997, but the US, the world's largest polluter, has not done so and many of the signatories have missed targets.