It doesn't matter how many solar panels you install if you don't simultaneously shut down coal and gas burners.

As Dutch elm disease spread across Britain in the 1970s, the country fell into mourning. When the sentinel trees that framed our horizons were felled, their loss was a constant topic of sad and angry conversation.

There's nothing good about ash dieback, but there is one useful thing that could be done: wherever possible, leave the dead trees to stand. There is more life in a dead tree than in a living tree: around 2,000 animal species in the UK rely on dead or dying wood for their survival.

While some livestock farms are much better than others, there are none in this country that look like natural ecosystems. Nature has no fences.

If we want to prevent both climate and ecological catastrophes, the key task is to minimise the amount of land we use to feed ourselves, while changing the way the remaining land is farmed. Instead, governments almost everywhere pour public money into planetary destruction.

Brexit, for all its likely harms, represents an opportunity to pay landowners and tenants to do something completely different, rather than spending yet more public money on trashing our life-support systems.

There is plenty of housing - for the rich. But a series of outrageous policies ensure that it remains inaccessible to the poor.

In politics, almost everywhere we see what looks like the externalisation of psychic wounds or deficits.

For some people, it is easier to command a nation, to send thousands to their deaths in unnecessary wars, to separate children from their families and inflict terrible suffering, than to process their own trauma and pain.

I believe that anyone who wants to stand in a national election should receive a course of psychotherapy. Completing the course should be a qualification for office. This wouldn't change the behaviour of psychopaths, but it might prevent some people who exercise power from imposing their own deep wounds on others.

I want to be represented by people who are thoughtful, self-aware and collaborative. What would a system that elevated such people look like?

The high seas - in other words, the oceans beyond the 200-mile national limits - are a lawless realm.

Until fishing is properly regulated and contained, we should withdraw our consent. Save your plastic bags by all means, but if you really want to make a difference, stop eating fish.

For some of Britain's most powerful people, hunting and shooting are primordial rights, and any challenge to them is treated as illegitimate. They assert ownership not only of the land but also of the social relationships surrounding it.

Landowners, farmers and gamekeepers, though they comprise a small minority of the rural population, claim to speak for everyone, and dismiss those who challenge them as interfering urbanites.

While some people have rejected capitalism gladly and swiftly, I've done so slowly and reluctantly. Part of the reason was that I could see no clear alternative: unlike some anti-capitalists, I have never been an enthusiast for state communism.

Economic growth is the aggregate effect of the quest to accumulate capital and extract profit. Capitalism collapses without growth, yet perpetual growth on a finite planet leads inexorably to environmental calamity.

As the scale of economic activity increases until capitalism affects everything, from the atmosphere to the deep ocean floor, the entire planet becomes a sacrifice zone: we all inhabit the periphery of the profit-making machine.

Healthy populations of predatory crabs and fish protect the carbon in salt marshes, as they prevent herbivorous crabs and snails wiping out the plants that hold the marshes together.

What I love about natural climate solutions is that we should be doing all these things anyway. Instead of making painful choices and deploying miserable means to a desirable end, we can defend ourselves from disaster by enhancing our world of wonders.

Technological change is essential, but to a natural historian it often feels cold and distancing.

Yes, the car is still useful - for a few people it's essential. It would make a good servant. But it has become our master, and it spoils everything it touches.

A central task for any campaign is to develop a narrative: a short, simple story explaining where we are, how we got here and where we need to go.

Successful movements also need an organisational model that allows them to keep growing.

In thinking about male identities, I'm struck by the inadequacy of the terms we use. The notion that men should be distant, domineering and self-seeking is often described as toxic masculinity, but this serves only to alienate those who might need most help.

The age-old mistake, which has stunted countless lives, is the assumption that because physical hardship in childhood makes you physically tough, emotional hardship must make you emotionally tough.

Those who deny their own feelings tend to deny other people's.

Humans, the supremely social mammals, are ethical and intellectual sponges. We unconsciously absorb, for good or ill, the influences that surround us.

The Enlightenment ideal, which all universities claim to endorse, is that everyone should think for themselves.

Only one of the many life support systems on which we depend - soils, aquifers, rainfall, ice, the pattern of winds and currents, pollinators, biological abundance and diversity - need fail for everything to slide.

Wildlife film-makers I know tell me that the effort to portray what looks like an untouched ecosystem becomes harder every year. They have to choose their camera angles ever more carefully to exclude the evidence of destruction, travel further to find the Edens they depict.

Farming and fishing are the major causes of the collapse of both marine and terrestrial ecosystems. Meat - consumed in greater quantities by the rich than by the poor - is the strongest cause of all.

The struggle to save every possible species and ecosystem from the current wave of destruction is worthwhile. One day, perhaps within our lifetimes, they could repopulate a thriving world.

Even when political reporting is not reduced to personality, political photography is. An article might offer depth and complexity, but is illustrated with a photo of one of the 10 politicians whose picture must be attached to every news story.

Everyone should be free to learn; knowledge should be disseminated as widely as possible.

While open-access journals have grown rapidly, researchers still have to read the paywalled articles in commercial journals.

Regardless of what we consume, the sheer volume of consumption is overwhelming the Earth's living systems.

Defending the planet means changing the world.

The ideology of consumption is so prevalent that it has become invisible: it is the plastic soup in which we swim.

As a child and young adult, I delighted in being able to identify almost any wild plant or animal.

I have lived long enough to witness the vanishing of wild mammals, butterflies, mayflies, songbirds and fish that I once feared my grandchildren would not experience: it has all happened faster than even the pessimists predicted.

The government argues that without a price, the living world is accorded no value, so irrational decisions are made. By costing nature, you ensure that it commands the investment and protection that other forms of capital attract.

Sometimes I wonder whether anything is learned in conservation, or whether the big NGOs are for ever destined to follow a circular track, endlessly repeating their mistakes.

If I could turn back the clock, magically deleting my prostate cancer, the surgery I needed and its complications, would I do so? It seems an odd question. But I find it surprisingly hard to answer.

We should seek to love our lives and live fully, but not to extend them indefinitely. We should love our children exuberantly, but not cling to them or curtail their freedoms. We should treasure the material world without seeking to own and control it.

When you are diagnosed with prostate cancer, your condition is ranked on the Gleason Score, which measures its level of aggression. Mine is graded at seven out of 10. But this doesn't tell me where I stand in general.

Fear hems us in, stops us from thinking clearly, and prevents us from either challenging oppression or engaging calmly with the impersonal fates.

In talking about my cancer with family and friends, I feel the love that I know will get me through this. The old strategy of suffering in silence could not have been more misguided.

We should be cautious about embracing data before it is published in the academic press, and must always avoid treating correlation as causation.

The people of each generation perceive the state of the ecosystems they encountered in their childhood as normal and natural. When wildlife is depleted, we might notice the loss, but we are unaware that the baseline by which we judge the decline is in fact a state of extreme depletion.