My understanding would be that it refers to someone or group who's message is seen as unimportant or irrelevant. With relation to green culture the message might not be presented in a relatable manner to a diverse group of people.

Today the most successful information is presenting by instilling fear in people. This is also used to promote green culture, but in my opinion fear is short lives, which necessitate more messages evoking fear. Although green culture is necessary long term buy in is needed to address the green issues.

I'll suggest promoting success stories like how China is transforming the desert and linking it to how small green behavioral changes in peoples daily lives can help contribute to a greener future. When small green behavior changes are instilled in us it will carry from one generation to the next as the norm solving current problem but also easing future green behavior changes where required.