REPORTER: Aaron Lewis
The Kenyan highlands has some of the richest agricultural land in the world, land which may be Kenya's ticket out of poverty. It's morning on the Sunripe organic farm. 200 labourers have just arrived to start their day working the fields. They come from all over the district, often on foot, because jobs are scarce.
ISABELLE, (Translation): It took me ages to get this job, I wouldn't like it to end.
Sunripe pays double the average wage of a dollar a day, so many wait a long time to start work here. Mark Machewa waited a year.
MARK MACHEWA, (Translation): What I can say is that finding work in Kenya is not easy. So we appreciate what we have.
These farm hands are often the only breadwinner in an extended family. It's hard work here, like many of Kenya's most successful farms, Sunripe grows organic produce by hand, without machines or fertilizers.
JOHN NDUNGU, MANAGER: It is a mixture of soils and composts.
John Ndungu is Sunripes manager. He's spent years building up the farm, introducing innovations like dense shrubs used as barriers to stop beetles and worms break down compost.
JOHN NDUNGU: We control pests like thrips, white flies, aphids, caterpillars, using chillies, using garlic, using fermented milk, and all that works pretty well for us.
This dedication has paid off. After years of investment, they've been able to meet the stringent standards of European watchdogs agencies, like the UK Soil Association which means top dollar in Western supermarkets. But all this could be about to change, as the idea of 'food miles' takes hold in Europe and John faces losing his biggest export market.
JOHN NDUNGU: It's becoming a concern in the UK market that a lot of the produce coming from Kenya, or from Africa, being air-freighted is contributing to carbon emissions.
REPORTER: And how seriously is that being pursued now in your understanding?
JOHN NDUNGU: That was taken very seriously, there was a lot of concern, people are worried, it's sending shivers up the spines of the people involved in the industry.
Now rumours are spreading across the farm that there may be bad times ahead.
ISABELLE, (Translation): On radio and TV they say the companies in Africa that produce food for export are in trouble and could be shut down any time.
MARK MACHEWA, (Translation): This definitely will not be good because these farms provide us with jobs. So if they close, it's going to be very difficult to find new jobs.
JOHN NDUNGU: These people depend on us for their livelihood, for the livelihood of their extended families and, as a company, we have invested in land, equipment and if this is to be suddenly withdrawn, it has a big effect to us primarily, to the people we employ, and to the stakeholders who depend on our operation.
In fact Kenya's Ministry of Agriculture says that the nation's entire economy is being propelled by the boom in agricultural exports.
N.C. CHEPKWONY, MINISTRY OF AGRICULTURE: The growth rate of the country was about 5.8% while agriculture sector contributed about 14% in growth, most of this was due to horticulture.
The cold London morning starts early for Paul Jardine who hand-delivers boxes of locally grown organic vegetables. He's at the forefront of the food miles movement that could spell trouble for Kenya's farmers.
PAUL JARDINE: There's always a pleasure in seeing them, that you're giving them nice food.
Unlike most of the fruit and vegetables eaten in the United Kingdom, nothing here has been air-freighted. For customers like Anna Ashton, food miles is a critical factor in what she buys.
ANNA ASHTON: Oh, and some bacon and some burgers. We do try to buy locally produced food wherever possible, or food that sort of takes that into consideration. And so we're not buying food that's been air-freighted, we try to buy seasonal food, and it's something that my husband and I have been talking about quite a lot. And it does seem to make a big difference to us to put that sort of thought into where our food comes from.
REPORTER: It's interesting that you said that you don't want to buy food that has been air-freighted, right off the top of your head, why?
ANNA ASHTON: Because of the contribution it makes to global warming. As I understand it, air freight, air travel, is a huge contributor to global warming so anything we can do to try to stop that situation I think is very helpful.
The Ashton family is part of a growing trend, it's called the local food movement, an obsession with local food is moving into the British mainstream.
TREVOR DATSON, TESCO SPOKESMAN: Green consumption has to be the norm, and not just something for the educated middle classes to do. We need everybody to be able to afford green products.
Trevor Datson is a spokesman for Tesco, one of the largest supermarket chains in the world.
TREVOR DATSON: We're actually going to cut the amount of products on our shelves that are air-freighted by 1%, down to 1%, and we've actually already achieved that target.
The remaining air-freighted products that are squeezed into the 1% allowance are being clearly labelled with bright blue stickers as a warning to climate conscious consumers. It's a major shift in a country that imports half its vegetables and 95% of its fruit. And Tesco is not alone. The most powerful organic certification body in the UK is taking a hard look at food miles.
KENNETH HAYES, SOIL ASSOCIATION: There was an expectation, particularly in regards to organic, because we have very strong environmental principles, that perhaps air freight wasn't in line with those principles, and that consumers would expect organic food not necessarily to be air-freighted. So that is something that was put to us by the public essentially.
The Soil Association has been encouraging Africa's farmers to grow organic export produce for more than a decade but worries about climate change have forced it to think again.
KENNETH HAYES: The research that we've seen is, when you look at the supply chain, and when you look at production, processing, packaging and distribution, air freight is the prominent emitter of carbon and greenhouse gases within that whole supply chain.
That triggered alarm bells at the Soil Association. It's now looking at a range of options to fight climate change.
KENNETH HAYES: We presented five options in our consultative paper, which were all options which are all being considered by other people at the moment, and these were labelling air freight, carbon offsetting, a selective ban, with exemptions in cases of developing countries for example, or a complete ban, and these are things which are being implemented by other organizations and businesses.
Back in Kenya, advocacy groups are strongly opposed.
EUSTACE KIARII, KENYAN FARMING ADVOCATE: We encourage the Soil Association to not take this decision for now, as the result would be an economic disaster for the country.
The reason it will be an economic disaster is because fertile land is Kenya's principal resource. People living here enjoy a year-round harvest and the lives of the farmers creates very little carbon pollution, the average Kenyan creates less than 3% of the carbon pollution generated by a person living in the UK.
EUSTACE KIARII: It's not Africans who are causing global warming, it's the developed countries who are causing global warming. But who is suffering more? It's Africans. And you see even the developed countries like the UK are still proposing to put more stringent measures to make more Africans suffer. It's a paradox, an ironic paradox.
Kenyan growers are suspicious the food miles debate is just a front for protecting European farmers.
EUSTACE KIARII: Indeed, it's just another non-tariff barrier to trade. We have proven to the world that we can compete with European farmers. Why then should organisations like the Soil Association create barriers that will just restrict more Africans from accessing premium markets?
To back their argument, Kenya's exporters point out that transport is only one part of a product's carbon-footprint, to see its total environmental impact you have to also look at the pollution caused by its packaging and production. This is especially true for the organic fresh-cut flowers that are big business in Kenya and also a target of air freight bans, heated greenhouses are not needed here unlike in Europe, where heating crops is a big source of carbon pollution.
N.C. CHEPKWONY: And I want to say that air freighting forms a minimal percentage of the total energy that is used in the production line of any produce. So targeting that alone is not fair.
REPORTER: How do you operate differently from a UK farmer?
JOHN NDUNGU: A UK farm is 100% mechanised. We are only about 15% mechanised. We do all our operations by manual labour. We employ people to do a lot of things that the UK farmer does using machinery.
GUY WATSON, RIVERFORD ORGANIC FARM: That argument is complete crap. It's just people playing PR games to justify their commercial interest.
Guy Watson runs the Riverford Organic Farm in South Devon, England. It's one of the UK'S first and biggest organic businesses.
GUY WATSON: We've looked at the carbon footprint of what we do here. Generally speaking, it looks as if the energy used in moving around the vegetables, even just in the UK, not considering imports, is three or four times greater than the energy used in growing them.
And he believes air-freighting over thousands of kilometres is many times worse.
GUY WATSON: You're just getting to the position where the actual transport is outweighing any savings you have in production, many times over, probably as much as 100 times over. There may be some socioeconomic gains to growing in Kenya, but there are absolutely no environmental gains.
A handful of Londoners are so concerned about food miles they've decided to reduce theirs to zero. Dan and Alex Burner moved out of their inner-city flat in May in search of more space.
DAN BURNER: So really one of the priorities was to have a garden, and that immediately took us out of areas that were like the one we were renting, and moved us slightly further out of town. So that's how we came to be here.
REPORTER: Was that a worthwhile trade-off?
DAN BURNER: Yes. Absolutely. This has been a source of so much for us, lots of jam making, preserves, our ice-cream, there are only so many pears you can eat.
A surprising amount of their staple food grows right here in their backyard.
DAN BURNER: The vegetables, the beetroot, the carrot, the lettuce, things like that, they've pretty much provided all the vegetables we've needed.
ALEX: Yep, we pretty much have all the fruit and veg we've had, has been from this garden.
For Dan and Alex, daily food preparation takes a little more time and effort. But they believe the inconvenience is worth it, if it helps fight climate change.
ALEX BURNER: People take the mickey a little bit. But I think there's definitely a growing sense that this is the way forward, and that people are going to have to make more of an effort around how they structure their lives. Because, I think, as global warming increases, this is going to be how people produce their food.
If the Burners are right and their home-grown food is the future for Europe, it's a future with little room for Africa's farmers. That's a dilemma they can't resolve.
DAN BURNER: We don't just care about what lands on our table, we care about what's going on in the world. We don't necessarily have the answers to the bigger picture but we see what the problems are. And as with anything that's worth fixing, there's probably no quick fix.
Back in Kenya, Kairu King'oro's farm is a tiny organic plot outside of Nairobi, he's poured everything he has into this land hoping it will pay off in export dollars in the future. He's one of hundreds of small holders whose investment is now under threat.
KAIRU KING'ORO: If we don't get a good market for our produce, people will suffer.
And climate change is already making life hard for Kairu, seasonal rainfall is becoming less predictable every year, seriously affecting his harvest.
KAIRU KING'ORO: In August through from July to September it is all rain, so there is a lot of change in the weather pattern in Kenya today.
There is a hard paradox at work here, Kenyans are being hurt by the actions taken to stem climate change but Africa will be hit hard if nothing is done to slow global warming and so far the Kenyan Government has done very little to prepare for the potential ravages of climate change.
REPORTER: Has the Ministry of Agriculture made any plans as to how it will affect business as temperatures go up over the next century?
N.C. CHEPKWONY: Not yet?
Faced with a future of higher oil prices and a carbon-conscious public, Britain's Soil Association says that regardless of what they decide about the future of organic farming in Africa, Kenyan agriculture can't keep relying on air freight forever.
KENNETH HAYES: Actually this is inherently unsustainable, and that there is a responsibility for the people in the West who are buying these products in encouraging a trade which is so dependent on a fossil fuel. It throws the issues of climate change and development into sharp relief, it really does challenge us on how we go forward in addressing climate change.
Even British organic farmers who will benefit from limits on air-freighted imports believe that a ban targeting the world's poorest countries may be too politically hot to push through.
GUY WATSON: The suggestion that some middle-class person in the West who is probably still driving their 4x4 is denying the potential for an improvement in living standards in a developing country is just unacceptable. It won't happen.
Guy Watson may be confident of the outcome but Kenya's farmers are still anxiously awaiting the Soil Association's decision. It's expected within days and for Africans, the big challenge will be living with the consequences.
MARK MACHEWA, (Translation): Because they will have disadvantaged many people. The whole of Kenya relies on agriculture. We rely on these vegetables that you see. Almost everything relies on this. So, if the market there for our produce dries up it will be very unfair.