They may not see you point because you you are panicking about a hot summer.
Going back years and years and few hot summers in a row wasn't unusual. Nor was bad winters.
If that's what you are using as proof, it no wonder they aren't listening. I also don't think that buying organic is really going to help much. Organic doesn't mean it's not travelled.
The things people can do is as you suggested. Reduce your packaging usage. Especially coffee cups, take away food packaging, plastics, recycle where possible, shop for local produce where possible.
Really watch what you buy and think about landfill before you buy something. However don't let it take over your life.
I work for one of the countries top businesses and they have banned single use food and beverage containers from their offices and provided everyone with water bottle and mug.
We all work towards making sure things are recycled if possible and it's a team effort. We ensure that we all do it and gently point people in the right direction if they are using the wrong bin etc.
Getting people on board is a big thing. But hysteria over last summer won't do that.