It’s not hard to see why everyone’s worried about plastic. The seas are unquestionably heavily polluted with plastic， as are some rivers and streams. Frans Timmermans， vice-president of the European Commission1， recently declared war on“single-use plastics that take five seconds to produce， are used for five minutes， then take 500 years to break down again.” It’s utterly depressing to think that plastic bags， yoghurt pots and disposable cups will be the chief archaeological2 relics of our age.

我們十分清楚塑料袋对于环境的危害：生产一个塑料袋只需要五秒钟，但是自然降解一个塑料袋却要花上五百年。抵制一次性塑料制品成为许多国家流行的环保政策。但是在这种狂热抵制的背后，我们忽视了许多更为复杂的问题：塑料制品的替代品真的更加环保吗？对塑料袋征税真的能起到保护环境的作用吗？又有什么更好的政策能鼓励人们主动回收利用塑料制品呢？

　　But when public opinion is so much in agreement on an issue， we should all be on our guard. It’s exactly when everyone agrees about an issue that bad decisions are made， some with awful and far-reaching unintended consequences.
　　The trouble with the new plastic obsession is the same trouble we had with carbon emissions 20 years ago. Environmental policy becomes so focused on one specific， fashionable problem that no one notices that the proposed solutions are， in other ways， making matters worse. In the case of carbon emissions， the Blair government3 （along with the European Commission） became so fixated in cutting the amount of CO2 that they encouraged motorists to switch to diesel—inadvertently sanctioning an increase in deadly nitrogen oxide emissions.4
　　This is the risk we now face with the war on plastic. If supermarkets follow through on their recent promises to ban plastic packaging， it’s a struggle to see how they will keep fruit and veg fresh for long. The very people we’ve tried so hard to encourage to eat well will revert back to Turkey Twizzlers. It is easy now to forget what shopping was like before supermarkets transformed the British diet in the 1970s， before chiller cabinets and the revolution in food packaging， to which the traditional seasonal shortage of fresh vegetables was eliminated owes a lot.

　　You’re only really entitled to feel virtuous about eschewing5 plastic if you look carefully into the effect on the environment of your chosen alternative. Take Gove’s coffee cup.6 There have already been rumblings7 about overharvesting of bamboo in China’s Sichuan Province. There is more general concern， too， about the wide-scale use of plant-based alternatives to oil-derived plastics. As long as bioplastic remains a niche product for concerned middle classes，8 the land issue isn’t important. If bioplastics are adopted across industry， it will be a genuine cause for concern. 　　According to a report on the environmental impact of bioplastics published by the government in 2010， it takes 1.7 square metres of arable land to grow each kg of PLA9， one of the main bioplastics， which can be used as a substitute for many types of food packaging. Europe consumes almost 60 million tonnes of plastic a year. If all this packaging were instead grown in fields， it would take up 40，000 square miles—nearly a tenth of all arable land currently under cultivation in Europe. And what about the carbon emissions from biodegradable10 plastics？ They tend to decompose straight to methane，11 a greenhouse gas measured to have 20 times the potency of CO2.
　　What is remarkable about the war against plastics is that hostilities were first started a decade and a half ago， but were stopped in their tracks by some powerful evidence. The plastic bag tax was first tried in Ireland in 2002， when a 15 cent charge per bag was similarly found to cut bag use by 90 per cent. If shoppers are going without any kind of bag and trying to balance numerous items in their hands， that can be counted as an environmental gain. But if they have switched to other types of bag then the benefits are harder to discern12. When a plastic bag tax was proposed in Scotland， the devolved13 government launched a two-year assessment comparing the“life-cycle analysis” of single-use plastic bags against paper bags. In 2005， it came to the surprising conclusion that a“paper bag has a more adverse impact than a plastic bag for most of the environmental issues considered”.
　　Six years later， Defra14 compared the environmental impact of plastic bags with its rivals. That study came to the remarkable conclusion that a cotton shopping bag would have to be used 173 times before it became responsible for fewer carbon emissions than a plastic bag—cotton being a very intensive crop requiring large amounts of water and fertiliser.
　　Single-use plastic bags also performed better environmentally than paper bags and biodegradable plastic bags and plastic “bags for life”. And this was assuming that “single-use” plastic bags are just that—when of course they are often used for other purposes， such as bin liners15. When Wales introduced its own 5p plastic bag levy16 seven years ago， it led to a 25 per cent surge in the sales of pedal bin liners—to replace the supermarket bags that people had previously been using. Moreover， the plastic bag levy has done nothing to counter the wasteful packing being used in online sales.