In March, an estimated 150,000 people marched in Australia. This "strike" could be bigger.

The children will be joined by employees of well-meaning businesses in Canberra. Phoebe Howe from Community Shapers, a Canberra call centre, said its 40 staff had been encouraged to go to the march.

And Michael Reid, owner of an information technology business, said he had long been concerned about climate change so he had decided to close the office and encourage his five staff to "strike".

All this is very well. Private companies may do what they like.

But we are told that ACT government employees have also been told that they can join the strike.

Public servants are paid by the taxpayer. The work they do (or not do) while they are on strike is work foregone unless they make it up at some other time. If they don't, this would be a work stoppage funded out of taxes.

There is an important point to be made here. We do not doubt that climate change is a very serious issue, up there with the risk of nuclear war as a threat to the future of the planet.

But encouraging public servants to join strikes risks politicising their work, while also putting those not in agreement with the strikes at uncomfortable odds with their colleagues.

There is a concept used by social researchers called "moral credentialing" where people come to feel unconsciously that a good deed justifies a bad deed. In studies in the United States, participants were given the opportunity to disagree with blatantly sexist statements but were then found to be more likely to favour a man for a stereotypically "male job". It's as though they knew they were on the side of the angels so a little devilry was permissible. Do environmentalists fly in aircraft in the same way, one wonders.

The danger of gesture politics is that it is a substitute for real action involving sacrifice. If all those in Friday's protest vow not to take a flight for, say, the next five years, we would be more convinced of the worth of the gesture.

Instead of a strike, why don't businesses and the government have a work-in on a Saturday? If they are serious about the undoubted dangers of climate change, this genuine sacrifice would be a much more powerful way of showing it. Cameras could be invited to show the world how strongly they feel - so strongly that they would give up their own time for no pay. Now, that would be a loud signal.

And the students from school could do the same. In Saturday art classes, they could create colourful banners with powerful green slogans. They could stage a public reading of strong environmentalist texts. This would be truly inspiring.

Government ministers could also commit to using buses rather than atmosphere-damaging flights to Sydney. The direct buses from Northbourne Avenue take the same amount of time as a flight, city-centre to city-centre. Switching from planes would help the environment - and the tax-payer.

There are many practical ways politicians, school students and businesses could raise awareness of the need for climate action while doing something about it at the same time.