A gradual increase in Earth’s atmospheric greenhouse gases is expected to make global weather more volatile over the next century. This might include higher temperatures, less rain, changing wind patterns, and rising sea levels. Higher temperatures and more turbulent weather will affect everything — from which trees to which wildlife cover the region to what crops farmers raise to how cities allocate water. Weather unpredictability would make dry years more common and wet years less effective. The result could be more reliance on rain-intensive crops or more garden watering. The overall impact of global warming on Midwestern agriculture remains unclear because it is not as well studied as that on the coasts. While some disagreement continues over how much of the warming comes from human activity and how much comes from natural climate trends, most scientists now agree that humans contribute significantly to global warming. A new map from the National Arbor Day Foundation has moved plant hardiness zones northward and where Minnesota was in Zones 3 and 4, it is now (on the Arbor Day map) in Zones 3, 4, and 5. The University of Minnesota Extension Horticulturists have urged caution in accepting these new zones, because hardiness is influenced by rainfall, plant vigor, and drought as well as minimum winter temperatures. Just because the past few winters in the Midwest have been above normal, we cannot be certain we have consistently moved to warmer winters. You can minimize your garden risk by purchasing smaller herbaceous plants and shrubs that are recommended for a warmer zone. Some of this information is specific for certain USDA hardiness zones and may not apply to your local conditions. For more information on this topic, choose a related topic link above, or contact your local County Extension office.

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