Climate change is now mainstream media fodder. But, what is the "greenhouse gas effect," and how might it affect our gardening future?
The sun heats the earth, and some of this heat radiates back into space, just as heat rises from a hot summer sidewalk warming the air. In the atmosphere, water vapor, clouds, carbon dioxide, methane and other gases absorb this radiant heat. In a presentation on climate change at the Impacts of Climate Change on Horticulture Symposium in 2003, Bill Moomaw from Tuft University compared these gases to the glass windows in a car creating the "hot car" effect.
Our human activities, such as the use of fossil fuels and the release of methane and other gases from agriculture, livestock, landfills and industry, are changing the atmosphere. Moomaw points out that the climate of Maine in 2050 will be like New Jersey's climate now. By 2100, Maine's climate will be like today's climate in North Carolina. We will see increased temperatures, increased smog, rising sea levels, decreasing snow and ice cover, melting glaciers and changed precipitation patterns. Some places will receive more rain and have more floods, while other areas will suffer more frequent and prolonged droughts.
We will see more plant pests, such as aphids and spider mites, more fungal diseases and more invasive weeds. However, agriculture and forest productivity may increase in some locations and decline in others.
Rising carbon dioxide levels directly affect photosynthesis. Plants will grow more rapidly and be sturdier. Initially, this sounds like a positive thing to gardeners, but as a result, plants will also require more maintenance to keep up with the excess growth. More plant cover also increases humidity. Spring will come earlier and autumn will last longer, increasing the length of growing seasons. Again, this sounds great, but summers will be much hotter with more evaporation. Will northern Nevada have enough precipitation to meet the needs of our plants and households? Summer rainfall is supposed to decrease in some parts of the world. In Nevada, we don't have much summer rainfall to begin with, so it is hard to imagine that we could have less.
There could be less frost and frost damage and reduced winter chilling. Will there be enough cold to produce fruit on our fruit trees? On the bright side, we could enjoy spring bulbs and flowers earlier than we currently do. Richard Bisgrove, senior lecturer at the Centre for Horticulture and Landscape at the University of Reading, United Kingdom, predicts "increased opportunities for adventurous gardening but an increased difficulty for conservation of historically important gardens and plant collections."
Life will be interesting in our gardens as the world warms.
For more information on gardening, contact me, 887-2252 or email@example.com, or your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at www.unce.unr.edu. "Ask a Master Gardener" by e-mailing firstname.lastname@example.org.
-- JoAnne Skelly is the Carson City/Storey County Extension Educator for University of Nevada Cooperative Extension.