Greens are opposing moves to extend the runway at the oldest working airport in England.
They say the proposals are part of plans by bosses at Shoreham Airport to accommodate larger planes.
A recent report by consultants showed a gap in the market for short-haul flights to other UK airports and business flights to northern European cities.
South-East Green MEP Caroline Lucas, who represents Sussex in Europe, visited the site with Moyra Martin, who is standing in the local elections in Marine ward today.
She said aviation was the fastest growing source of greenhouse gas emissions and this problem would get worse if there were more planes.
Dr Lucas added: "To try to satisfy these demands is folly. We need instead to improve the quality of less damaging transport, in particular the rail network.
"Unless it is challenged, the Government's love affair with the aviation industry will turn the country into one giant runway."
Ms Martin said extending the runway was based on the false premise that it would increase prosperity in Shoreham but it would bring more people into an area where there was a housing shortage.
Councillor Mike Middleton, who chairs the airport authority, denied there were plans to lengthen the runway.
He added: "We are looking generally at the airport and how we can bring it into the future."
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