The silver lining to the fears about an economic slump is that a few diplomatic problems may get easier.

Russia and Iran, buoyed up by demand for oil, may be more cautious about taking on the West. Reforms which have proved hard to push through in boomtime - such as Europe's Common Agricultural Policy - may be easier when governments feel short of money.

The new fears may also divert attention from terrorist threats, with which the US, with fitful support from other governments, has been so preoccupied. That would be no bad thing. It might strip some of the belligerence and hyperbole out of the rhetoric, as voters pressed their leaders to concentrate on their real economic suffering rather than the notion of possible future attack.

These are thin compensation, of course. Most problems get harder in times of recession, if only because most are solved with the help of cash, whether development aid, military force, or social benefits at home. That goes for the conflict in Afghanistan, any thoughts of expanding the European Union further - and above all, for trade, where the reflex, in many countries, will now be to shut the doors to protect vulnerable industries.

Worries about a slowdown might also take the heat out of the new drive to tackle climate change, because a slump would cause pollution to grow more slowly, and because people might be less tolerant of making expensive changes. They can help only by adding to a mood of fearfulness.

Three years after the Gleneagles summit at which Tony Blair pledged new commitment to development, the new mood seems unlikely to help that cause, particularly with the sight of China pouring millions into Africa to secure oil contracts.

But in the sudden change of mood, when the drama in financial markets has eclipsed news from the battlefields of Iraq and Afghanistan, there may be exceptions - problems that have been stuck for years, which suddenly yield a bit.

That happened seven years ago, when the September 11 attacks suddenly made other problems seem trivial. The heightened revulsion for terrorism helped to bring Sinn Fein to the negotiating table. It distracted India and Pakistan from their 50-year obsession with Kashmir, and gave them common cause in fighting Islamic extremists.

It also took the wind out of the more militant end of the anti-globalisation movement, say British officials who handle intelligence on such groups. It made them look perverse and myopic in their choice of causes that the world should worry most about.

The new slowdown in the US and Europe is not, unfortunately, likely to bring the price of oil sharply lower, such is the demand from China (which estimates suggest will nearly treble in the next two decades). But it may undermine Russia's confidence in the cash it will get from Europe's captive market. A slump will also squeeze Iran's economy - and so increase the effect of the sanctions.

The new concerns should puncture the EU's tolerance for spending too much money on subsidies, including those to farms, the easy option compared to renegotiating the deals. It may even - but this could go either way - inject life into a final attempt to pin down the Doha Round world trade deal. The fears will stir up protectionism, of course - but may also persuade governments that they really need the benefits of a deal, and this is the last chance.

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