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Newsletter 29th February 2008

- Being green is not a black and white issue - Are drought-tolerant plants on the horizon?

Being green is not a black and white issue

Modern environmentalism is a product of prosperity. As the fortunate populations of the developed world take for granted that they are well fed, live in comfortable houses and have energy on tap to meet all their needs, their concerns move towards issues such as nature conservation and the general state of the environment: a perfect illustration of Maslow's hierarchy of needs.

This is good and healthy. We should be thoughtful about our use of resources and changes we make to landscapes. Our understanding of the intrinsic worth of other species and our aesthetic values set us apart from other animals and form one of the bases of our humanity. But having accepted this, there remain difficult choices. How far should we take our prioritisation of the environment? Which choices really make a difference and which just give us a warm glow of misplaced satisfaction?

A case in point is the use of cars for short journeys. All our instincts tell us that, given sufficient time, we should walk to he local shop rather than drive. If our personal fitness is the important issue, then this is undoubtedly true. However, if our aim is to save energy and carbon dioxide emissions, the situation is much less clear-cut. We know our car uses a certain amount of fuel, but walking also requires energy, and that needs to be replaced by food. And that food requires fertilizer, spraying against pests, harvesting and transport. If it is an animal product, then the energy input is increased further, because a kilo of plant protein produces less than a kilo of animal protein. You may not eat more on a particular day just because you left the car at home, but over time energy input and expenditure will be broadly in balance.

To take another example much in the news, there is now a concerted campaign against plastic carrier bags, which seem to have become the poster child for our disregard for the environment. Marks and Spencer is the first major retailer to announce that it will charge customers for bags in a bid to reduce their use. It remains to be seen whether others follow the lead. If this leads to fewer bags being used, this may be a visible sign of action, but its effect on energy use would be minuscule. Apart from which, most free plastic bags are actually reused at least once, usually as waste-bin liners.

And if people were dissuaded from using plastic bags by having to pay for them, what would they do instead? The most likely thing is that bags would be re-used a little more, but they will still end up in landfill (unless they are incinerated and used to generate power or useful heat). Perhaps the most persuasive argument against their use is aesthetic: discarded bags are an eyesore. But even this is more a question of people's behaviour than the bags themselves: anything carelessly thrown away is equally unacceptable.

Analyzing the total energy balance in the production, distribution and use of a product seems the most objective way to determine greenness. Life cycle analysis of disposable and reusable nappies, for example, produced the surprising result that disposables compared favourably when the energy costs of washing were factored in. Of course, that is not necessarily the whole picture, but it suggests that a choice to use towelling nappies may be less environmentally friendly than it seems at first sight.

Another contentious issue is "food miles". On the face of it, transporting food long distances (thousands of miles in many cases) seems wasteful and unreasonable. The assumption is that "eating local" is always preferable. The reality is somewhat different. Growing food efficiently and then shipping it long distances may actually be better in terms of overall energy expenditure than growing it locally. Classic examples are New Zealand lamb and Spanish tomatoes. Other factors also come into play. If we look at food miles in the context of the overall food chain, we find that the energy used by consumers in their trips to and from the shops is far greater than that from bulk food transport. And the human element must not be forgotten: airfreighting green beans or roses from Kenya provides employment in a country with few other comparative advantages.

The message then is not to ignore our impact on the environment, but to look at it in a broader and more balanced way. Humankind has an inevitable influence, and we should not be thoughtless about this. Nevertheless, to focus just on one issue – energy use, perhaps, or waste disposal – runs the risk of poor decision making, with little benefit. All things considered, we cannot eliminate our effect on the environment, but merely choose its form and degree. And there is no neat set of right and wrong answers.

Are drought-tolerant plants on the horizon?

The innovation which enabled every other aspect of human development was farming. There is nothing natural about clearing land and growing crops which have been bred to meet our own criteria and cannot survive in the wild. Whether they are grown intensively, organically, even bio-dynamically, is very much of secondary importance. We tend to forget this, because agriculture is so pervasive that it seems "natural". In clearing forests we have changed the ecological balance completely, favouring some species and disadvantaging others. We would certainly not consider skylarks as native birds in the UK if farmers did not provide a suitable habitat.

But we are still wary of new developments in farming, perhaps because the pace of change has accelerated so much. Now, research reported by scientists from the University of California in San Diego and the University of Helsinki gives promise that drought-tolerant crop plants could become a reality. They have discovered the mechanism by which plants control the opening of leaf pores (stomata). Closing them at times of water stress could increase the chances of surviving drought, and probably help to make use of irrigation water more efficient.

The researchers also found that the stomata close to protect the plant from damage when ozone levels rise, but at the same time this reduces the ability of carbon dioxide to be absorbed and so reduces overall photosynthetic efficiency. This is important because, other things being equal, higher levels of atmospheric carbon dioxide increase plant growth. The ability to influence plant growth and water use by genetic modification could yield enormous benefits in both industrialised and developing countries. Nevertheless, there will be those who resist the introduction of such crops.