By Victoria Averill
"What is global warming?", asks Samuel Mauthike, a small scale vegetable farmer in Kirinyaga, Kenya's central province, as he crouches down compressing the moist soil around his green bean plants.
How green are Kenya's exports?
"Is it something caused by us in Africa?"
Mr Mauthike, 32, like so many of the two million Kenyans who rely on the western world to import their flowers, fruit and vegetables for their livelihoods, has never heard of a carbon footprint either.
He points to the simple gravitational water irrigation system that flows through his smallholding, admitting he has never been in a plane, rarely travels by bus and uses nothing but his hands to grow, fertilise and harvest his top quality green beans, which then appear on a supermarket shelf in Europe.
Yet he and his fellow Kenyan farmers, whose lifelong carbon emissions are negligible compared with their counterparts in the West, are fast becoming the victims of a green campaign that could threaten their livelihoods.
A recent bold statement by UK supermarket Tesco ushering in "carbon friendly" measures - such as restricting the imports of air freighted goods by half and the introduction of "carbon counting" labelling - has had environmentalists dancing in the fresh produce aisles, but has left African horticulturists confused and concerned.
Fresh flowers, fruit and vegetables make up 65% of all exports from Kenya to the European Union (EU), according to the Fresh Produce Exporters Association of Kenya (FPEAK).
Half of this produce goes to the UK's supermarkets, generating at least £100m per year for this developing country.
The dependence on the UK market cannot be underestimated, says Stephen Mbithi Mwikya, chief executive of FPEAK.
For Kenya, horticulture is the country's second biggest foreign exchange earner after tourism.
"This announcement from Tesco is devastating", says Mr Mbithi.
"I think if things continue in this one-sided sensationalist way, purely targeting air freight, labelling our produce with aeroplanes and not looking at other aspects of production, it will cripple Kenya, it will cripple the economy," he says.
"I really don't believe this is what the consumer wants."
Producer and consumer confusion
Tesco says its new measures have been misunderstood, that it will not reduce imports from Africa as the continent is one of the regions it has promised to protect.
Kenyan livelihoods rely on European consumers
"Engagement with our African producers is very important to us", says Trevor Datson, spokesperson for Tesco, adding it is Africa that possibly stands to lose the most from global warming.
But the confusion over air miles, carbon miles and the "aeroplane" labelling of produce air freighted into the UK does not just lie with the African producer.
The consumer is also in a muddle.
Last week, UK development secretary Hilary Benn acknowledged the consumer's conundrum when faced with a choice - local produce or air freighted goods.
"The food miles debate poses a real dilemma," according to Mr Benn.
"People say I want to do my bit to stop climate change. So, should I only buy local and boycott produce from abroad, especially things flown in - or should I support poor farmers to improve their income, to take care of their families, to work and trade their way out of poverty?"
So should African producing countries feel threatened by the "green" revolution sweeping through their export markets?
Will labelling a packet of green beans from Kenya make a consumer positively discriminate against buying that product?
Bill Vorley, head of the sustainable markets group at the UK's International Institute for Environment and Development (IIED), believes African producers have every right to feel concerned.
IIED research has found that if consumers were to boycott fresh produce air freighted from Africa, UK's total emissions would be reduced by less than 0.1%.
In addition, Mr Vorley says, UK supermarkets are prone to reacting to consumer whims before consulting their suppliers.
"Tesco has to be very careful and bring people into the debate", he says.
"If we talk about business as a partner in development you have to have a dialogue with those who will face the consequences of your decisions".
This time around, those in the Kenyan horticultural industry say there has been no dialogue.
"We consider ourselves as partners with UK supermarkets", says Jane Ngige, chief executive of the Kenya Flower Council, whose membership represents more than 70% of flower exports from Kenya.
"It is very surprising not to have had Tesco communicate with us directly before this announcement.
"One minute we are talking about fair trade and market compliance, the next this is less of an issue and the issue is lessening the carbon footprint of the developed world possibly by cutting markets in Africa.
Kenyan farmers produce food that Europeans like
"It is so confusing."
For Africa to export to UK and European markets, a smallholder farmer has to adhere to stringent environmental and ethical standards, which is a lengthy and expensive procedure.
African producers have worked very closely with supermarkets to ensure that these rigorous certification procedures are followed through resulting in the quality product the consumer buys.
Lost export markets
Two hundred kilometres to the east of Kenya's capital, Nairobi, Peter Ndivo, a local farmer delivers his sacks of baby corn to the local "collecting point", a steel-roofed hut nestled amongst banana groves and fields of maize.
Ndivo is one of 600 farmers benefiting from a scheme run by the international non-governmental organisation Care, linking Kenyan farmers to international markets.
Five years ago he uprooted his tomato, cabbage and onion plants to make room for baby corn seedlings - a crop he had never seen and equally would not eat - but with an export market secured, and his income guaranteed, he felt he had everything to gain.
"I only grow this as I'm told it's what others like to eat and I can get a good price for it," he says.
"I can also pay my daughter's school fees."
French beans and mange tout may be the staple of a gourmet's supermarket basket, but according to the Fresh Produce Exporters Association of Kenya, these luxury vegetables that account for more than two thirds of Kenya's vegetable exports to supermarkets are not consumed by the domestic market.
For Kenyan farmers like Mr Ndivo, livelihoods are at risk.
The fear is a simple plane logo may brand their product as environmentally dangerous to eco-conscious consumers, thereby closing off the market that gives them their income.
"If countries don't want what we are growing I'll lose everything and so will the people I employ to help me sow and harvest," he says.
"The local market will not want any of this produce."