Phil Chapman is a geophysicist and astronautical engineer who lives in San Francisco. He was the first Australian to become a NASA astronaut.

"Disconcerting as it may be to true believers in global warming, the average temperature on Earth has remained steady or slowly declined during the past decade, despite the continued increase in the atmospheric concentration of carbon dioxide, and now the global temperature is falling precipitously.

All four agencies that track Earth's temperature (the Hadley Climate Research Unit in Britain, the NASA Goddard Institute for Space Studies in New York, the Christy group at the University of Alabama, and Remote Sensing Systems Inc in California) report that it cooled by about 0.7C in 2007. This is the fastest temperature change in the instrumental record and it puts us back where we were in 1930.

It is generally not possible to draw conclusions about climatic trends from events in a single year, so I would normally dismiss this cold snap as transient, pending what happens in the next few years.

This is where SOHO comes in. The sunspot number follows a cycle of somewhat variable length, averaging 11 years. The most recent minimum was in March last year. The new cycle, No.24, was supposed to start soon after that, with a gradual build-up in sunspot numbers.

It didn't happen. The first sunspot appeared in January this year and lasted only two days. A tiny spot appeared last Monday but vanished within 24 hours. Another little spot appeared this Monday. Pray that there will be many more, and soon.

The reason this matters is that there is a close correlation between variations in the sunspot cycle and Earth's climate. The previous time a cycle was delayed like this was in the Dalton Minimum, an especially cold period that lasted several decades from 1790.

We cannot really know, but my guess is that the odds are at least 50-50 that we will see significant cooling rather than warming in coming decades.

The probability that we are witnessing the onset of a real ice age is much less, perhaps one in 500, but not totally negligible.

All those urging action to curb global warming need to take off the blinkers and give some thought to what we should do if we are facing global cooling instead.

It will be difficult for people to face the truth when their reputations, careers, government grants or hopes for social change depend on global warming, but the fate of civilisation may be at stake.

In the famous words of Oliver Cromwell, "I beseech you, in the bowels of Christ, think it possible you may be mistaken."

My take, NOBODY studying climate has immunity from mistake, particularly the computer model faithfull. Prepare for the worst. Should AGW be vaild, reducing hydrocarbon burning in autos and for heating sounds like a good idea and for myriad other reasons. Hybrid autos & nukes for electricity. Should in contrast we face another Maunder Minimum scenario, there are actions as decribed in the article that would allieviate the worst.