Defending the planet means changing the world.

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

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

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

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.

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.

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.

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.

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.

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

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

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

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.

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.

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

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.

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.

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

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.

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.

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.

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.

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.

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.