Gardeners are the first observers of changes in climate. Their intimate knowledge of how plants respond to changes in temp, light, humidity, micro-climates and more gives them a sense of environmental change earlier than most of us. Most serious gardeners base their planting choices on hardiness maps that divide the planet into Zones which indicate average low winter temps.

Because we are near Lake Ontario, our climate is moderated by the slower changes in temperature of the water in the lake. It acts as a heat sink, stabilizing temps through seasonal changes. As a result our hardiness zone is warmer than those to the south of us. However, in recent years, our zone has changed to the next level warmer which cannot be explained by proximity to the lake. This change is graphically shown by this hardiness map comparing changes throughout North America in the period from 1990-2004. The striking thing about this is how the entire range of warmer zones is moving northward.

For my girlfriend, who is a plant fiend, this means we are increasingly able to plant semi-tropical plants in warmer areas of our garden without worrying about them wintering over. It’s not just us: municipal arborists in England are now replacing dying street trees with species that can survive warmer climates. Given the lifespan of a tree, this indicates a committment on their part to acceptance of warming.

Watch the gardeners….