The Pope called carbon offsets hypocritical, and said if taken to its logical conclusion the offset concept would lead to armaments companies building children's hospitals for those maimed by their bombs.

A look back at history will help us understand why the Pope feels quite so strongly. As early as 1095, the Catholic Church offered indulgences - remission against future sins - sometimes in return for a contribution to the Church.

Basically it was a licence to sin and really little different to a voluntary carbon offset - which enables a business or person to go on polluting as before whilst paying a little in an effort to reduce pollution elsewhere.

These indulgences came to a sticky end. Martin Luther objected to them in his '95 Theses' and although reformers had many complaints about the 16th Century Catholic Church, the practice of selling indulgences caused the most concern. It basically split the Church.

When we dropped carbon offsets on 15th Oct 2009 we called them a 'dangerous distraction' from the real job of reducing emissions. Sadly, in aviation the offset concept lives on. Despite being a major and growing cause of CO2 emissions (emitting as much as Germany and likely to account for 25 percent of the world's remaining carbon budget by 2050) aviation has been exempt from all international deals seeking to limit greenhouse gases. However, last year the first deal to include aviation was signed. Any increase in emissions from 2020 will need to be offset by activities like tree planting to soak up CO2. It is indulgences all over again.

Aviation's record in developing new fuels and technology to reduce carbon emissions is lamentable compared to other sectors and industries, and we need to ask why.

After vast investment, some Northern European countries' energy needs are met by more than 50 percent renewable fuels, and they are moving towards 100 percent targets. Within 10 years most new cars will be electric; India has already promised that the only cars sold there by 2030 will be electric.

Meanwhile, aviation is almost totally reliant on highly polluting kerosene. Investments in new technology and fuels are small and decreasing (get link from my future of tourism post) with the aviation manufacturers still focused on making aircraft more efficient and more cost effective for airlines to run. A carbon fibre 787 still needs two huge, kerosene-burning engines on the wings to fly.

Given aviation's obsession with offsets, and the sector's dramatically slower progress in renewable fuels than other sectors, one has to wonder whether carbon offsets have indeed been a 'dangerous distraction' from the job at hand.

To really get aviation focused on the future it would be better if we learn lessons from the past that 'indulgences' and offsets don't change behaviours and can in fact have disastrous consequences.

We need to remove barriers to the aviation sector investing in the future of electric planes, about which several commentators are optimistic. Ditching offsets would be a good start.

Rather than the aviation sector spending money on carbon offset schemes that won't change long term behaviours - and that the EU believes rarely work anyway (I have a link for this) - it would be better if they invested in new fuels and technologies.

In addition, by removing the 'fig leaf' of offsets, governments would see just how polluting aviation has become, and perhaps better support the sector's move from kerosene to renewable fuels more strongly. In the UK, the tourism industry could finally get real and accept that no heavily indebted government is going to drop one of its cheapest and easiest means of collecting taxes – Air Passenger Duty. Instead, the lobbying should shift to encouraging the government to at least use some of the £3bn raised to incentivise genuine carbon reduction by the aviation sector in the same way that electric and hybrid cars are subsidised.

The lesson from history is that we must all take responsibility for our actions, and that we can't pass that off elsewhere or to someone else. For the church, the ultimate effect of selling indulgences was the reformation and the irrevocable split of the Catholic Church. What will the ultimate effect be for the planet if we continue to fly as much as we want to (or feel we have a duty to be able to do), with only a few of us even bothering to pay for the carbon emission offset indulgence?

Read more of our blog posts here