Plant hardiness maps point to a warmer world

If, like so many Long Islanders, you’re a gardener, you’ll have to rethink when you plant your vegetables and flowers in the coming years.

That’s the conclusion drawn by the U.S. Department of Agriculture in its recently released Plant Hardiness Zone Map. The map is a guide to regional planting zones. It tells gardeners and farmers when they should plant. Plant hardiness zones are based on the average annual minimum temperature at a given location in winter.

According to the USDA, every planting zone in the U.S. is warmer by 5 degrees Fahrenheit since the map was last published 22 years ago. Part of the change, the agency says, is because data collection has become more accurate over the past two decades. But, it adds, better data do not account entirely for the change.

There is little doubt that the Earth is warming, according to the USDA. But the agency, wanting to stay out of the global-warming political fray, does not point to humans as climate-change drivers. It leaves it to us to draw our own conclusions.

The United Nations Intergovernmental Panel on Climate Change is now preparing its fifth assessment report on climate change, due out in 2014. In its fourth report, published in 2007, the panel of more than 2,000 scientists declared that it was “very likely” that “anthropogenic greenhouse gases” –– the carbon dioxide and methane we produce by burning fossil fuels –– are the primary cause of global warming.

Here’s the thing: Whether or not you believe in global warming or whether humans cause it, there are simple steps you can take to produce fewer greenhouse gases while saving yourself cash in the process:

• Grow a garden. The environmental movement likes to talk about locally grown food. If food is produced where people eat it, it doesn’t have to be shipped across country or from overseas, preventing countless pounds of greenhouse gases from ships, trains or trucks from being emitted into the atmosphere.

When you grow a garden, you can be sure that you’re eating the freshest organic vegetables possible. And if your garden is big enough, you could save hundreds in grocery bills annually.