Our natural world is disappearing before our eyes. We have to save it.

Perhaps this forgetfulness is protective. I have been averting my eyes. Because I cannot bear to see what we have done to nature, I no longer see nature itself; otherwise, the speed of loss would be unendurable. The collapse can be witnessed from one year to the next. The swift decline of the swift ( down 25% in five years ) is marked by the loss of the wild screams that, until very recently, filled the skies above my house. My ambition to see the seabird colonies of Shetland and St Kilda has been replaced by the intention never to visit those islands during the breeding season: I could not bear to see the empty cliffs, where populations have crashed by some 90% in the past two decades .

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. Walking in the countryside or snorkelling in the sea is now as painful to me as an art lover would find visits to a gallery, if on every occasion another old master had been cut from its frame.

The cause of this acceleration is no mystery. The United Nations reports that our use of natural resources has tripled in 40 years . The great expansion of mining, logging, meat production and industrial fishing is cleansing the planet of its wild places and natural wonders. What economists proclaim as progress, ecologists recognise as ruin.

This is what has driven the quadrupling of oceanic dead zones since 1950 ; the “biological annihilation” represented by the astonishing collapse of vertebrate populations; the rush to carve up the last intact forests ; the vanishing of coral reefs, glaciers and sea ice; the shrinkage of lakes , the drainage of wetlands. The living world is dying of consumption.

We have a fatal weakness: a failure to perceive incremental change. As natural systems shift from one state to another, we almost immediately forget what we have lost. I have to make a determined effort to remember what I saw in my youth. Could it really be true that every patch of nettles, at this time of year, was reamed with caterpillar holes? That flycatchers were so common I scarcely gave them a second glance? That the rivers, around the autumn equinox, were almost black with eels?

Others seem oblivious. When I have criticised current practice, farmers have sent me images of verdant monocultures of perennial ryegrass, with the message: “Look at this and try telling me we don’t look after nature.” It’s green, but it’s about as ecologically rich as an airport runway.

One reader, Michael Groves, records the shift he has seen in the field beside his house, where the grass that used to be cut for hay is now cut for silage. Watching the cutters being driven at great speed across the field, he realised that any remaining wildlife would be shredded. Soon afterwards, he saw a roe deer standing in the mown grass. She stayed throughout the day and the following night. When he went to investigate, he found her fawn, its legs amputated. “I felt sickened, angry and powerless … how long had it taken to die?” That “grass-fed meat” the magazines and restaurants fetishise? This is the reality.

When our memories are wiped as clean as the land, we fail to demand its restoration. Our forgetting is a gift to industrial lobby groups and the governments that serve them. Over the past few months I have been told repeatedly that the environment secretary, Michael Gove , gets it. I have said so myself: he genuinely seems to understand what the problems are and what needs to be done. Unfortunately, he doesn’t do it.

Gove cannot be blamed for all of the fiascos to which he has put his name. The 25-year plan for nature was, it seems, gutted by the prime minister’s office. The environmental watchdog he proposed was de-fanged by the Treasury (it has subsequently been lent some dentures by parliament ). Other failures are all his own work. In response to lobbying from sheep farmers, Gove has allowed ravens, a highly intelligent and long-lived species just beginning to recover from centuries of persecution, to be killed once more in order to protect lambs. There are 23 million sheep in this country and 7,400 pairs of ravens . Why must all other species give way to the white plague?

Responding to complaints that most of our national parks are wildlife deserts , Gove set up a commission to review them. But governments choose their conclusions in advance, through the appointments they make. A more dismal, backward-looking and uninspiring panel would be hard to find: not one of its members, as far as I can tell, has expressed a desire for significant change in our national parks, and most of them, if their past statements are anything to go by, are determined to keep them in their sheep-wrecked and grouse-trashed state.

Now the lobbyists demand a New Zealand settlement for farming after Brexit: deregulated, upscaled, hostile to both wildlife and the human eye. If they get their way no landscape, however treasured, will be safe from broiler sheds and mega dairy units, no river protected from runoff and pollution, no songbird saved from local extinction. The merger between Bayer and Monsanto brings together the manufacturer of the world’s most lethal pesticides with the manufacturer of the world’s most lethal herbicides. Already the concentrated power of these behemoths is a hazard to democracy; together they threaten both political and ecological disaster. Labour’s environment team has scarcely a word to say about any of it. Similarly, the big conservation groups have gone missing in inaction.

We forget even our own histories. We fail to recall, for example, that the 1945 Dower report envisaged wilder national parks than we now possess, and that the conservation white paper the government issued in 1947 called for the kind of large-scale protection that is considered edgy and innovative today. Remembering is a radical act.

That caterpillar, by the way, was a six-spot burnet : the larva of a stunning iridescent black and pink moth that once populated my neighbourhood. I will not allow myself to forget again: I will work to recover the knowledge I have lost. For I now see that without the power of memory, we cannot hope to defend the world we love.