Why is nothing in the world of green business ever simple?
Take London's plans for a ban on all free disposable carrier bags. At first glance this is a surely A Good Thing: almost two thirds of Londoners support the idea; a ban on plastic bags has proved highly successful in the Devon town of Modbury; most of the supermarkets are already pushing reusable bags as an alternative; and it would strike a blow against one of the most visible symbols of consumer waste.
But as soon as you start investigating the proposals everything starts to get confusing.
Despite the proposal's popularity the government - whilst committed to phasing out single use plastic carrier bags through its waste strategy - seems strangely unwilling to endorse a ban.
Spokespeople for both Defra and the Treasury are quick to cite the supposedly poor example of Ireland, which introduced a tax on plastic bags in 2002 with a similar goal of slashing the number of bags in circulation. They argue that far from slashing the use of plastic bags the move simply resulted in a surge in sales of heavier reusable bags and bin liners, which require more energy to manufacture and transport.
The UK Packaging and Industrial Films Association (PIFA) even claims to have uncovered Irish customs and excise figures show that while the use of thin plastic bags in Ireland plummeted following the introduction of the tax the total weight of plastic bags being imported into the country has increased as people buy alternatives.
Meanwhile, Irish shops have reportedly simply started handing out paper bags, which (almost incredibly)some argue have a greater environmental impact than plastic bags as they release carbon dioxide as they decompose.
All this sounds so counterintuitive it is easy to imagine a well organised plastic bag lobby has simply constructed an argument to suit its own ends and both the UK and Scottish governments, which shelved plans for an Irish style bag levy, have fallen for it.
This is certainly the view of a spokesman for the Irish department for the Environment, Heritage and local Government, who argues that evidence claiming overall use of plastic bags has increased is anecdotal, that use of plastic carrier bags has plummeted 90 per cent and that use of reusable bags has soared.
He also points out, not unreasonably, that Ireland has now stuck with the ban for around five years and earlier this year increased the levy to ensure it remains effective – a strange thing to do if it was not delivering a positive environmental impact.
The intuitive position remains that the Irish government must be in the right and the plastic bag lobby is attempting to muddy the waters of the debate.
It stands to reason that any tax or outright ban on carrier bags, such as that proposed in London, will lead to the increased use of heavier reusable plastic bags and bin liners – after all people still need to carry their shopping home and line their bins, but it is hard to believ this increase offset the environmental gains from a full ban.
For example, I have been using a small rucksack and three reusable plastic bags to carry shopping back from my supermarket for the last year; they are all still going strong and there is no way they are heavier than all the disposable bags I would otherwise have used. This would surely be the default position if a ban was enforced with more reusable bags being used, far fewer disposal bags being used and overall demand for plastic bags falling.
And yet, some observers maintain that the evidence from Ireland is to the contrary.
If the Irish government is as proud of its plastic bag policy as it appears then it owes it to every other national, state, city and local government currently considering a bag ban to put this debate to rest one way or another and commission a full audit into the overall environmental impact of its levy.
Perhaps then the decision for MPs voting on the London councils proposals would prove simple after all.
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