all the proof you need

Sunflowers are normally associated with warmer climates and scientists believe that global warming is responsible for allowing them to grow successfully in the northern isles. They were grown by Richard Herdman, an Orkney farmer, who scattered the seeds over two and a half acres of his dairy farm in the west Mainland area.

Ruth Dawkins, of the Stop Climate Chaos group, said the success of the sun-loving yellow flowers on Orkney was a sign of global warming.
The Telegraph (UK), 14 Oct 2008