Life on the edge

A wolf on a trailer, a raft for rhododendrons, a fallen rain forest - the Barbican's new exhibition shows how artists have responded to threats to the environment. Has Nature in art has become a puny, melancholy creature, asks Hari Kunzru
Heather and Ivan Morison's I Am So Sorry, Goodbye (2008), Radical Nature at the Barbican
Earth calling ... Heather and Ivan Morison's I Am So Sorry, Goodbye (2008), part of Radical Nature at the Barbican Centre, London. Photograph: Wig Worland Wig Worland/Public Domain

Judging by Radical Nature: Art and Architecture for a Changing Planet 1969-2009, Nature is in crisis. It's not just the familiar ecological message of the show - that the planet is fragile and we're not helping matters - but something more unsettling, almost uncanny. It feels like Nature is shrinking. Importantly, when it comes to art, Nature is not nature. Without the capital letter, nature is merely all that organic stuff around us; Nature, on the other hand, is an aesthetic category, which (to simplify considerably) turned up with romanticism. For the romantics, Nature came in two basic flavours. There was the Sublime: mountains, storms, icebergs and so forth - forces which, in their vastness and intensity, had the power to overwhelm human senses. Then there was the Beautiful: nature that was bounded, reasonable and pleasing - a rolling English landscape, a field of daffodils. In the world outside the gallery we still find plenty of examples of sublime, often terrifying nature. Tsunamis sweep across tourist beaches. Earthquakes swallow suburban housing developments. But at the Barbican, Nature is a puny, sickly creature. It inspires melancholy, nostalgia, pity, gallows humour. It's not even really beautiful any more. It's a problem, a remnant, something that needs to be conserved and argued for. The chances of being romantically overwhelmed are slim.

Nature in its uncapitalised form is actually present in the gallery, in the form of living plants and trees. There are some rhododendrons on a floating island. There's a functioning vegetable plot, an ornamental garden inside a shed and even a patch of rainforest startlingly flipped on its side so the trees grow parallel to the floor. We see these green things up against materials that speak of technology and artificiality - mirrored surfaces, steel, the white gallery walls. The effect is unsettling. Is Nature now just a point-and-click option, a bit of rhetoric for artists and architects to deploy, just as they might choose to use Super 8 film, or porn mags, or gallons of Hershey's chocolate syrup? It seems to have been domesticated, controlled. Somehow it doesn't seem quite ... natural.

The proposition of this show is an interesting and timely one. It offers us a generation of artists who in the late 60s and early 70s, as the first wave of environmentalism took hold, began to experiment with new ways of relating to the natural world. It then juxtaposes them with a new generation of environmentally conscious artists who have rediscovered this tradition and are wrestling with our current anxieties about the future of the planet. Looking around at the eco-disaster of postwar urban consumerism, the 70s artists made the claim that it was no longer good enough to "appreciate" nature from a safe, aesthetic distance. The very idea of beauty was getting in our way as we tried to make sense of our skewed relationship to the earth. Wasn't there something obscene about landscape painting when so much land was being swallowed up by cities? Didn't our fetishisation of pretty, natural scenes contribute to a wilful blindness to all the ugliness we were creating? We didn't want to look at all the waste, the pollution, the depleted habitats.

Informed by the utopianism of the period, some artists started to look for radically new ways of being in the world. A potent symbol of this was Buckminster Fuller's Dymaxion Map, which offered a more accurate representation of the relative sizes of the continents than the standard projections. With proportion restored, perhaps arrogance and greed would make way for humility and coexistence.

In this spirit, the Ant Farm collective, best known for giant inflatables, imagined an interface between humans and dolphins, a way for two intelligent species to meet on equal terms, a project they termed the "Dolphin Embassy". The land artist Robert Smithson made monumental structures such as the famous Spiral Jetty which juts out into the Great Salt Lake in Utah, an intervention into nature that is simultaneously a grand artistic gesture and a humble rearrangement of stones.

Artists associated with conceptualism, a movement largely uninterested in pretty objects and very interested in systems, tried to highlight the interconnectedness of things. So Joseph Beuys built a circuit of tubes and pumped honey through it, powered by a ship's engine lubricated with margarine. Machines, organisms, food, fuel. Was there really such a radical opposition between "Nature" and "Culture", "Natural" and "Artificial", or even "Nature" and "Man"?

Interconnectedness is an important thought for anyone trying to understand the environment. Now that "ecosystem" is an everyday word, it's hard to remember how new these ideas were to a culture unused to looking at the world in terms of circuits, feedback, distributed networks, webs of cause and effect. It's perhaps a weakness of the Barbican show that it doesn't offer much in the way of context for its displays. One wall text mentions the utopian architectural work of the Archigram group of architects, who imagined cities floating, walking, assembling and disassembling themselves, but we don't get to see any of this. Nor do we get to see the most influential environmental image of all, the Nasa photograph of the Earth seen from space, which became an icon after Stewart Brand's successful campaign to get Nasa to release it into the public domain.

The curators have taken the decision to show the works as stand- alone contemporary art, rather than offering us cultural history. This was probably the best solution (such a show would have to have been much larger, for one thing, and would have subordinated the work to the curation), but it makes some of the pieces quite opaque, particularly as much of it is hard to present effectively in a gallery. Why? Because much of it didn't (and still doesn't) look like anything most people associate with art.

Mierle Laderman Ukeles personally said thanks to every single sanitation worker in New York, and drove around in a mirrored garbage truck, all to try to get people to realise that managing waste is vital to urban life, even if we don't like to look at the stuff. Newton Harrison and Helen Mayer Harrison put shrimp farms and orchards into galleries, with instructions on how to replicate the work using easily available household materials. Hans Haacke tinkered with natural processes such as plant growth, freezing and water purification, activities shown here by a grass mound and some rather uninspiring photographs.

This is exactly the kind of artistic activity which, even today, gets many people hot under the collar, because it doesn't result in attractively crafted objects. It has the quality of research, an intellectual exploration that, frustratingly, is often only patchily presented in the Barbican's limited space. Because of this, if you're at all interested, you should invest in the excellent catalogue, which shows a lot of work not in the gallery, and often makes much better sense than the show itself.

It would be very easy to walk past the Beuys display and see nothing but some old machinery and an (actually unrelated) film. I defy anyone to get interested in the wonderful Center for Land Use Interpretation from the presentation in Radical Nature. This LA-based group has been researching forgotten, marginal and unusual landscapes since the mid-90s, and has profoundly influenced a whole generation of artists and writers. Sadly, you won't be able to tell that from a slideshow of an oil pipeline and an internet terminal.

What of the rest of the younger generation of artists? At the entrance, the visitor is greeted by Mark Dion's Mobile Wilderness Unit - Wolf, an object that epitomises the threatened, melancholy quality that surrounds the natural world, at least as presented in this show. The wolf in question is taxidermised, supplied with a rock, some plants and part of a tree, and mounted on a trailer, ready to be carted off to the next location. Dion's black humour is a fitting opener - the joke being that, of course, real habitat isn't portable, and try as we might, endangered species are one amenity we can't take with us like campers trundling around with trailbikes and gas barbecues. A similar joke about portability is the basis of Simon Starling's Island for Weeds, which provides a survival raft for rhododendrons, a non-native plant which became a pest in the Scottish ecosystem. Starling's much misunderstood Shedboatshed, which helped to win him the Turner prize, was a shed he dismantled, fashioned into a boat, punted down the river and rebuilt into a shed. The art was as much in the process of transformation as in the "finished" object, and showed Starling's inheritance from the 70s conceptualists in this show. Starling's practice, which involves a lot of quixotic quests (often on a bike) and alchemical transformations, is rich and varied, and usually has a satisfyingly "aesthetic" outcome.

Also good to look at is the pleasingly crafty I Am So Sorry, Goodbye, by Heather and Ivan Morison, a domed pavilion that comes on like something out of Middle Earth by way of the Whole Earth Catalog, and was clearly inspired by the dwellings that popped up around the world as part of the alternative-living movement in the 60s. The Morisons' other structures, many of them located in their own tract of Welsh woodland, are a form of "architecture without architects", and bear little relationship to the faux-humble plywood modernism that usually results when architectural firms are asked to "think green".

The most dramatic pieces in the show are Henrik Håkanson's 90-degree-flipped Fallen Forest (a concise eco-statement if ever there was one) and Tomas Saraceno's whimsical *3x12MW, a floating structure of clear plastic spheres, tethered to the gallery floor and draped with tillandsia, a plant that derives all its nutrition from the air. Saraceno dreams of an "airport city", a 60s-style Nutopia free of the political and social constraints of earthbound life.

By contrast to such grand gestures, Lara Almarcegui's modest booklet of wasteland sites in the Lea Valley (future home of the Olympics) is initially unwelcoming. Why should we care about her black and white photos of dull bits of east London? What's to be gleaned from her terse, factual accounts of their history and future use? It's only when you discover more (from the catalogue) about her art, that you see her little book stems from a quirky and rather romantic sensibility, which leads her to negotiate with city councils to save waste ground from development, and pile building materials next to soon-to-be-demolished structures, like ingredients at a cooking demonstration - "Here's one I prepared earlier ..."

If one thing unifies the second generation of Radical Nature's artists, it's a certain pragmatism. This may seem an odd thing to say of people who put wolves on trailers and build rafts for plants, but in a show where it's often hard to tell whether a piece was made in 1973 or 2003 it's one of the few areas where they seem to separate themselves from their predecessors. If the 70s generation was about global ideas and blue-sky thinking, there's now a certain modesty in the air. No one believes we're about to enter a new age. It's more about making the best of the old one. Projects are conceived in local terms and (barring floating cities) are less about saving the world than recovering some flotsam and jetsam from the collapse. This is perhaps another source of the pervasive sense of sadness I felt going round the show - the feeling that, 40 years ago, there was a sense of possibility that has since vanished.

In any exhibition of this kind, one always finds oneself disagreeing with some of the curatorial decisions. I could have done without the ever-bland Anya Gallaccio, whose decorative biennial fodder (here it's a tree) could have made way for Amy Balkin, the radical Californian artist whose legal battles to make a piece of desert land truly "public" (This Is the Public Domain) and to create a global "climate park" in the atmosphere (Public Smog) show that the field has moved further on than one might think from wandering round the Barbican gallery.

Likewise, Natalie Jeremijenko's numerous explorations of the boundaries between animals, humans and the environment - robotic feral dogs, wrestling stag beetles and reciprocal zoos - could have bumped A12's amusing but essentially trivial garden shed. Where are the guerrilla gardening projects that have sprung up around the world? Where are the numerous experiments with biotech art, by people such as Eduardo Kac and the Critical Art Ensemble? Radical artistic approaches to Nature have gone a lot further than this exhibition suggests. Perhaps the inclusion of some of this work would have made an interesting show into a great one, dispelling the feeling that contemporary artists have yet to go much beyond the heroic explorations of the 70s.

Perhaps inevitably, the image that has stayed with me in the days since I saw Radical Nature is from this earlier period - the picture of Agnes Denes standing in the wheatfield she planted on waste ground in the shadow of the twin towers in 1982. The woman with the staff, waist-deep in yellow wheat, which stretches away until, shockingly, it ends in the glass and steel of New York's financial district, speaks about many things - global commerce, waste, a queasy nostalgia for an idealised agrarian past. Denes's work is being recreated in Dalston, as part of Radical Nature. Go and see what it looks like against the backdrop of a part of London that's just fought (and lost) a battle against aggressive development, seeing several heritage buildings demolished to make way for a huge tower block.

Radical Nature is at the Barbican Art Gallery, London, until 18 October. Tel 020 7638 4141.