If you're still planning your summer holiday, don't be fooled by Canada's green image and Alberta's famed Rocky Mountains. Canada is the surprising home to the most destructive project on Earth, the Alberta tar sands.

Today, Corporate Ethics International is launching an advertising campaign to encourage the British people to scrutinise what's going on in Alberta.

Tar sands are a mixture of sand, water, clay and bitumen, which can be processed into synthetic crude oil at great cost to the environment. It takes up to four barrels of water to produce just one barrel of tar sands crude. Producing a barrel of tar sands oil releases three times more carbon than conventional oil. Up to 11m litres of contaminated water are discharged every day from toxic tailing ponds so large they can be seen from space.

In the process of recklessly expanding the tar sands industry over the last decade, the rights of First Nation peoples have been trampled and their health threatened.

An area the size of England is at risk, and the fight against climate change is doomed if the tar sands are fully developed.

If industry gets its way, the expansion of the tar sands will continue, and petrol and diesel derived from bitumen will flood into Europe. If we don't stop them, you will be putting oil from tar sands in your tank within a year or two.

Canadians admire Britain and care about what British people think, and that would be enough to cause us to ask you to become allies in this effort. Yet there are more British connections to the tar sands.

In the previous parliament, Liberal Democrat MP Norman Baker signed an early day motion criticising the tar sands, but the new coalition government has yet to take a stance.

Shell and BP operate tar sands mines, and are the target of serious efforts in the City to swear off tar sands. But so far, neither company has responded.

The British government, through its shares in Royal Bank of Scotland and other banks, is funding this environmental outrage.

And tomorrow activists from Climate Camp are setting up near RBS headquarters on the edge of Edinburgh to protest against its investments in tar sands and other dirty fuels.

The British people now have the opportunity to take their own stand against the tar sands travesty, by pledging not to visit Alberta.

The British government can also show leadership by:

• Working with the EU to reverse – not continue – the concessions made to allow highly polluting Canadian oil into the UK through the next round of trade negotiations.

• Using the public shareholding in the big banks to stop investment in the expansion of tar sands.

• Encouraging the Parliamentary Contributory Pension Fund to stop investing in companies with links to tar sands production.

The Canadian government is whitewashing and greenwashing the tar sands, suppressing unfavourable reports and pressing the US and EU to continue their oil addiction in the name of energy security. It has even lobbied to weaken an EU fuel directive which would disadvantage high carbon fuels such as tar sands oil.

No issue is more important to the future of our planet than climate and energy. Now, when we are finally on the cusp of real change, the tar sands are standing in the way of an economy driven by renewable sources of energy. The Alberta government has put the reputation of the province and the entire country at risk. Its own people have asked it to rethink, but to no avail. So it's our turn – and your turn – to Rethink Alberta.

• Kenny Bruno is campaign co-ordinator at Corporate Ethics International, a non-profit US-based environmental organisation.