Did you clock the government's new national risk register, published by the Cabinet Office? It was widely reported as putting pandemic flu as potentially the most lethal threat mankind is facing.

I'm sure that's sensible, for reasons explained below. NHS managers should know this stuff. I should add that a terrorist attack with stolen nuclear weapons was apparently excluded from the heading "malicious attacks" only because there is no precedent.

Precedents abound for all listed options, which are themselves a fascinating reminder of hazards we routinely face. Not major earthquakes like China's pre-Olympic horror, but familiar foes like storms and - from sea, river and rain - floods.

We take air, sea, rail and road accidents for granted. But they are listed too: no major air crash for example since Kegworth's 47 deaths in 1989.

En garde

Such calm analysis helps put us on guard (how would you cope with loss of power, staff, site access, IT, water, etc, the report asks managers) but also provides perspectives. The great storm of October 1987 brought down 15 million trees but killed few people because it occurred at night. The smaller daytime storm of 1990 was more lethal.

Global warming is likely to make for fewer winters like 1962-63, the coldest in 250 years, whereas we can expect more hot summers (not 2008 obviously) like 2003 - which caused 2,045 extra UK deaths - 1976 or 1911. The South East's drought of 2004-06 was the worst for 200 years. Britain knows these things: we have the records.

It's a similar story with flooding. The traumatic east coast flood of 1953 killed 307 people (more in the Netherlands) and led to better coastal protection. The summer floods in 2007 taught valuable lessons.

Learning from history

And that's really the point, isn't it, for government, local authority "resilience forums" and firms, for health professionals and trusts.

Changing weather on our tiny island, plus decades of bomb threats (we're still digging up Hitler's), have made the UK a prevention pioneer. In a crisis, planning matters - as the excellent emergency response to 7/7 showed.

Thus something called the Heat-Health Watch was introduced after 2003 and claims credit for fewer heat deaths in the hot spell of 2006 (680), which piled respiratory, sunburn and even food poisoning burdens on hospitals.

What about disease? The report stresses the obvious: in a mobile, globalised world new horrors can travel fast, the zoonotic kinds that move between animals and humans, as well as troublesome animal pests like foot and mouth, bluetongue and swine fever. Some 12 million Brits who live abroad could bring trouble home with them in a crisis.

Unknown future

The nasty viral infection known as West Nile virus has not reached Britain, though it has been spreading in the US since 1999. "Experts agree there is a high probability of another influenza pandemic occurring," the report says - but no one can say when or what.

Factually speaking the 1918 "Spanish flu" outbreak was one of three 20th century pandemics, killing 20-40 million people worldwide (far more than the First World War), the "Asian flu" attacks of 1957 and 1968 being much less fatal, at one to four million.

It has always been this column's policy to mock the media's pandemic panic whenever a case of avian flu kills a migrant bird. But the answer is sensible preparation, including notification networks and flu vaccine.

Vital preparation

As with terrorism, it will happen. As with SARS, the duty of politicians and officials is to prepare. That is where China did well with its earthquake and the Bush administration did so badly by New Orleans before - and after - Hurricane Katrina.

We all understand the dangers of nuclear war. But anyone who doubts the power of pandemics should check out Lester K Little's Plague and the End of Antiquity: the Pandemic of 541-750. Arriving in Egypt it had even reached far-flung Britain by 664 where the Venerable Bede survived to describe its devastation of the late Roman world.

What exactly was it? Possibly bubonic plague like its better-documented successor, the Black Death. Archaeologists and biologists can't be sure.

Plague leaves few memorials.