The rich and famous have recently associated themselves with a number of causes, ranging from Fairtrade to Darfur. Even Christian Aid has bought into “celebratisation” with its promotion of Bamako involving Danny Glover.

But how much does this relationship actually benefit the causes these actors/musicians/politicians say they support?

The most fashionable of the “pop culture” campaigns may be climate change.

With Al Gore promoting yet another set of concerts and Julia Roberts appearing on the cover of a Vanity Fair “Green Issue”, it is difficult to not associate climate change with entertainment. But does their involvement help?

Celebrities can raise public awareness extremely quickly using their media exposure. Through interviews and changing their lifestyles they can communicate the message to people who might not otherwise be interested.

But results can sometimes take a long time and then only be temporary.

Cultural shifts like loads of people buying Fairtrade coffee can take years to come about. We don’t have years for people to cut their carbon emissions. They need to do it now.

If celebrities endorse an issue, it might make people change their behaviour just to be fashionable. This might mean people return to their old ways once the fad ends.

Also, in the case of social justice issues, traditional power structures are reinforced when the most powerful people speak in the name of the least powerful.

No campaign should rely on celebrity activists alone. They should be used to raise awareness of the issue but not to create a cultural revolution.

To accomplish this, the message should always come first and be emphasised far more than the person.

The Fairtrade movement does this well. Some of its posters feature stars whilst others show local growers and they always prominently showcase the Fairtrade mark.

Like most issues in advocacy, ordinary activists must approach celebrity culture with reasonable expectations. Sheryl Crow alone may not change the world, but all of us working together can.