A walk in the intensively farmed countryside near my home in Cambridgeshire is a good place to assess what environmentalists have achieved in recent decades, and to think about the challenges ahead. Not so long ago, you would have been lucky to see a buzzard or a hobby, let alone a marsh harrier. But if you go to the right places now, you can easily see these birds. Improved habitat and species protection, ecosystem restoration, and the phase-out of toxic pesticides are among the reasons why. It's not all positive on the environment front these days, but it's certainly better than many would have hoped for in the 1970s.
The damage being caused by acid rain has also improved, because of new laws to reduce sulphur emissions from large power stations. Positive action continues, with EU law requiring the closure of Europe's most polluting power stations. Because of this, forests and lakes across the continent are recovering. Even on the global stage there has been progress. The chemicals that depleted the planet's ozone layer have been largely phased out, and it is hoped that this atmospheric shield will be largely restored later in the 21st century.
I was once involved in work to prevent the extinction of endangered parrots. Many of them were critically endangered, down to a last few birds. Twenty years later, none of them are extinct, most have increased in number, and a couple of species that were feared lost have been "rediscovered".
Here in the UK, the air we breathe is mostly cleaner, many once polluted rivers have more healthy fish and insect populations, we are recycling more, and political engagement with environmental issues has never been stronger. All this, and a whole lot more, happened because of determined environmental work by organisations and individuals going back over decades. But this is just the start of what's needed.
Rapid climate change threatens massive environmental damage, while the global-scale degradation of ecosystems is causing a wave of extinctions as, for example, rainforests are cleared to make way for plantations of palm oil and fields of soya. Surging demand for natural resources in emerging economies is generating planet-wide shockwaves that are not only causing environmental stress, but also economic problems, as elevated demand pushes up prices. On top of that, there is rapid population increase.
Considering all this, the positive gains to date seem like a layer of sandbags laid out to hold back a tsunami. The gathering wave is huge, its impacts will be profound, and we need a different level of action to avoid its worst consequences.
The frontline environmental challenges have now moved firmly on to the global stage. The solutions they demand go way beyond the banning of particular chemicals, protecting a particular piece of land, or the better regulation of different industrial sectors. Nothing short of a restructuring of our societies and economies is needed. This has been coming for some time, of course, so why is it so difficult to adopt the changes needed?
Partly it is for practical reasons. We have become used to cheap energy, food and natural resources; our infrastructure, lifestyles and economy now depend on that continuing. To end this dependency requires fundamental change, and in a democracy like ours that, in turn, will rely on public support. The process of transition can be assisted by political leadership, but at heart some tough choices need to be made, and, in the absence of dead bodies here and now, we are finding it really tough to make them.
And then there is the trap of economic globalisation. We have expanded our economy on the back of ever more global integration. Global stresses are increasingly apparent, but we are finding it impossible to disentangle ourselves. Calls to protect UK "competitiveness" discourage politicians from taking steps to intervene in building a more sustainable economy at home. Instead, leaders seek to fix the creaking system with more of the same. Gordon Brown's calls for oil output to increase in the face of rising prices is a recent case in point.
Another set of challenges emerge from how the public receives messages about global change. Because there are such huge - and mainly negative - ramifications, the tendency is to either deny there is a problem ("The science is uncertain"), make some excuses ("Why bother doing anything here when China is causing so much damage?"), or to feel utterly disempowered ("It's too difficult and expensive to change, and anyway what difference can I make?").
Add to all this the political activities of various vested interests - such as the oil, motor and power companies, which have a vast economic stake in the status quo - and the quagmire deepens.
There is a way through all this, but it will need some different emphases compared with much of the environmental action taken over the last three decades.
The first shift is to adopt frank, credible and positive solutions. Pressure for change could in the past be mobilised by targeting environmental "baddies". That often worked to build public support for regulation on polluters or landowners. Aside from agreeing with new laws, most people didn't need to lift a finger. Now it's different. The climate, biodiversity and resource crunch cannot be solved by any one sector - all of us must play a part, including in how we live. People generally don't vote for things they believe will hurt them, and if we are to get buy-in for changes that will affect the majority of people, then the changes advocated will need to be positive.
Another shift of emphasis is toward economic incentives. There isn't time to ditch capitalism, but we do need to create better regulations and new markets through incentives that have the support of business. That requires environmental advocates to collaborate with corporations and the financial sector. Radical action is needed to build markets in clean technologies - and that will move faster if environmentalists and corporates can work together more effectively. Many of what might be regarded as "old corporates" are a dead loss, but new companies with different values are now emerging. Some of these are going faster than governments and could really be an engine for great change.
In order to solve global problems, we need a different kind of globalisation, based on different global networks, global agreements, and global level playing fields. This, in turn, suggests that western environmental bodies should put far more of their resources into building up their partner organisations in other countries, especially those in the developing world. In fast-growing emerging economies in particular, it is necessary to urgently create a new politics that sees development and environment as complementary and overlapping - rather than competing - agendas.
A different emphasis will need to be built into organisations' campaign strategies. Campaigners should seek common cause with human rights activists and labour unions, as well as economic actors. Conservation groups need to broaden their horizons to embrace questions of consumption and the economy. Development groups must deepen their ecological analysis, not least because efforts to end poverty are being massively undermined by environmental change.
The science is largely done, and now it is the politics and public perception that need to be changed. To do this work, environmentalists must retain principles, but it is large-scale practical outcomes that must be most urgently pursued - even if they may not be perfect.
As for me, I may be stepping down from Friends of the Earth, but I'm certainly not leaving the campaign for a sustainable society.
· Tony Juniper has worked for Friends of the Earth for 18 years, the last six as director. Later this month, he is leaving to become a special adviser to the Prince's Rainforest Project, and a senior associate with the Cambridge University programme for industry.
Originally published by The Guardian.