Global Greenhouse

A new greenhouse can unleash your plot’s growing potential, but the altered climate it brings has plenty to teach us about caring for a far larger, shared greenhouse.

By John Walker. Published in Kitchen Garden, August 2009.

It’s just topped 30C. Underfoot, it’s dust-dry. My seedlings are a-wilting. A lizard has just scurried away between the slate in my walls. I’m sweltering in the heat. It’s late May, and it’s a scorcher.

My little vignette might conjure up the sort of conditions you’d expect to find in some arid, sun-scorched Mediterranean back yard. But I’m experiencing this altered climate first-hand, right here on my own greenhouse doorstep, in uncharacteristically sun-drenched North Wales. The heat, the dust, the shrivelling and the lizard are all down to a bit of very local, human-induced climate change.

Satellite view of earth, the 'global greenhouse'.

We all live in an ever-warming, increasingly crowded ‘greenhouse’. Leaving this one closed and unventilated could risk catastrophe for millions of people, and for countless other non-human species.

On the day I flagged as temperatures soared, a report called ‘The anatomy of a silent crisis’ was launched by the Global Humanitarian Forum (GHF). Its vision is of ‘a world where the full potential of the global society is harnessed for eradicating human suffering.’ And there’s plenty of suffering about. The report, which looks at the full impact of climate change on global human society, warns that our increasingly topsy-turvy climate is already causing 300,000 deaths a year, and that it’s ‘seriously affecting’ 325 million people. It says that almost two-thirds of all human beings on the planet are now classed as ‘vulnerable’ due to climate change, and that 500 million are at ‘extreme risk’. The GHF has clout: it’s fronted by former United Nations Secretary-General Kofi Annan.

Humanitarians are folk who devote themselves to the promotion of human welfare – the health, happiness and fortunes of people. Health and happiness – isn’t that what gardening, especially food growing, is all about? After all, we plotters don’t just sit back and admire the stuff we grow, we eat it, too. We’re blessed with good fortune.

Climate change is anything but local. As we pump more and more ‘greenhouse gases’ into the atmosphere, primarily carbon dioxide (CO2), our planet is retaining more and more of the heat it receives from the sun. As global temperatures rise, climate systems worldwide are shifting shape and changing their behaviour. Even subtle changes can have devastating consequences for those most at risk, namely the untold numbers of folk eking out an existence in the ‘developing’ world – precisely those highlighted in the GHF report. I managed to save my shrivelling seedlings with emergency watering, but even if they had not survived, the worst I’d have experienced is intense disappointment. Not starvation – or even worse.

John Walker, earth-friendly gardening and environment writer and author's greenhouse, powered by zero carbon and free, renewable modern sunshine.

A new lean-to has transformed my garden’s growing potential, but making, getting, and installing it has gently turned up the heat in our much larger ‘global greenhouse’

My ‘very local’ bit of North Waleian climate change is human-made in the strictest sense: by putting up a new 2.4 by 5.5m (8 by 18ft) lean-to greenhouse this spring, I’ve radically altered the microclimate over precisely 13.3 square metres (144 square feet) of the earth. The sun still shines on these 13.3 square metres, just as it always has, but the difference now is that the glass of the greenhouse – just like the wafer-thin skin of life-supporting atmosphere surrounding our planet – is soaking up and trapping more of the sun’s heat. It was morbidly tempting, on that burning May day, to shut the vents and doors and to experience, for myself, for as long as I could bear it, something of the GHF’s ‘silent crisis’.

No wonder global warming is also known as the ‘greenhouse effect’. Maintaining our current trajectory as a species, and continuing to belch out CO2, especially here in the ‘developed’ world, is akin to shutting the doors and vents of our shared global ‘greenhouse’. The consequences of leaving any greenhouse sealed up and unwatered on a scorching blue-sky day are, as gardeners know, potentially disastrous.

Anyone gardening in an earth-friendly, organic way is doing so out of an innate concern for the welfare of the world around us; it’s about far more than saving money during an ephemeral recession. Organic gardening draws us inexorably closer to nature, invites us to look closely at the role our gardens play in the web of life, and urges us to revere as well as work with it. You and I are a part of that web. We are all familiar with the idea that gardening is good for ‘the environment’. But could gardening also be, in the broadest sense, ‘good’ (or indeed ‘bad’) for people, too?

“By putting up a new 2.4m x 5.5m (8ft x 18ft) lean-to greenhouse this spring, I’ve dramatically altered the microclimate over precisely 13.3sq m (144sq ft) of the earth”

The answer depends on how you go about your gardening, and whether you stop to give a thought to how far the effects of how you garden actually reach. Throw a stone into a still pond and the ripples will eventually find every nook. Everything we do in the garden or at the allotment can have positive or negative effects, both near and far. Gardeners produce searching ripples, too.

Let’s take our raison d’être: growing food. We know that growing our own is a ‘good’ thing to do. We grow ultra-locally, slashing the resources needed for packaging, promotion and transport. If we grow organically, we stop potentially harmful cocktails of synthetic, oil-derived chemicals getting into our bodies and into ecosystems generally. If we use planet-friendly, peat-free composts, we help keep peat bogs intact, and help keep the vast quantities of CO2 they squirrel away for us safely locked in the ground.

These are all examples, if you like, of ‘good’ ripples that help reduce the amount of CO2 going into the atmosphere. They’re the equivalent of keeping the global greenhouse vents open so that things don’t fry.

Winter squash seedlings in biodegradable pots just after watering on a scorching spring day.

I got to my flagging winter squash seedlings in time. If they had perished in May’s mini heatwave, I’d have been irritated, not facing malnutrition – or perhaps death.

But what about the paper, plastic and foil needed to package up even organic seeds? And where did the seeds come from? Perhaps they were grown by some of the GHF’s climate-vulnerable folk, in far-off lands. What of all that plastic, manufactured from oil, that carries our peat-free compost to us? How about all the fuel that’s burnt to get those vegetable plugs, plants and seed potatoes, themselves packaged in cardboard, plastic and much else, to our letterboxes? Where did all those plastic pots, tubs and seed trays come from? All the paper and ink to make a seed catalogue has to come from somewhere; DVD gardening catalogues need plastic to make them, energy to ship them from overseas, and power to play them on our greedy computer screens.

Think of all the oil needed to make fleeces, crop covers, and the other must-haves that make our organic food gardens so successful and enable us to avoid chemical quick fixes. Perhaps these materials can be recycled and live again – but how much energy will that demand? The next time you switch on a propagator, or start heating a greenhouse in January or February, picture the belching chimney stacks at your local power station. Think of the metal, timber and plastic that makes a polytunnel.

I’m still thinking about the glass, metal and plastic that comprises my new greenhouse, about the fuel used to get it and its builder’s here, about what powered the cordless drills, about the astonishing number of plastic bags of cement and ballast it took to make the brick base and the concrete floor, and about the energy needed to make the aluminium staging, and to get it here.

We kitchen gardeners are truly blessed to have a patch of this earth to call our own. While growing organically puts us ahead of the game in helping to keep the planet’s vents open, the health, happiness and fortunes of people elsewhere in the global greenhouse hinge on us doing plenty more.

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