It's a big threat to our tree canopy. The more mild our winters become the increased threat to invasive pests and disease. EAB is especially devastating and unlike DED, it seems like only a matter of time before it arrives in Alberta. That's why i'm constantly complaining about the lack of initiative in planting/ experimenting with new species. It seems like we are convinced that only species that were hardy back in the 70s are acceptable to plant now when in fact are winters are relatively milder than even 30 years ago. For example, we haven't had a -35 low in decades (at the airport) when it used to be common that our coldest temperature of the year was sub -35 (extreme minimum temp is a common standard used to determine plant hardiness). So it is worth it for the city to try out new varieties so that we are not caught flat footed if EAB or another blight hits our tree canopy.