In Kansas, researchers have collected more than a hundred years' worth of data about temperatures, rainfall, and weather patterns. From the perspective of a single year or even a decade or two, you might not notice much of a difference. There are seasons. Winters are still colder than summers. Kansas is one of those states with a reputation for fickle weather, anyway. Don't like this cold winter day? Just you wait a week; you'll be wearing shorts. Yet if you zoom out and look at the century, patterns emerge. The average winter temperatures have gone up by 2 degrees Fahrenheit. Summer has been more stable, with an increase of only .6 degrees. In general, during the last century, Kansas has had fewer relatively cold days, while the number of relatively warm days has increased. When those increases happen also matters. During both winter and summer, average nighttime temperatures have increased more than average daytime temperatures have.
That doesn't sound like much, but it makes a difference in practical ways. In Merriam, Kansas, there are plants thriving today that probably couldn't have survived thirty years ago. When I was born, home gardeners in Merriam chose the seeds they'd plant outdoors by finding species that were rated to USDA Hardiness Zone 5—meaning that those plants could survive winter temperatures as lowa's –20 degrees. By the time I graduated from high school in 1999, the Kansas City metro, along with most of Kansas, had been upgraded to Hardiness Zone 6. Winter was no longer likely to be so frigid. If a plant could survive a few days of zero-degree temperatures, it could probably live in Merriam just fine.
That opens up more possibilities for creative green thumbs. There aren't a lot of buildings in Kansas that are covered with the trailing green fingers of English ivy, but today, if you wanted a little ivy-covered cottage on the prairie—or an ivy-covered fence surrounding your metro backyard—you could grow it, without much worry of winter killing the plants. If English ivy doesn't sound like a particularly horrible fate, that's because climate change isn't inherently good or bad, in and of itself. It's all about how those changes affect people. We might like some of the results—English ivy can thrive, and even Kansas's many food crops are likely to grow better, at least in the short term—but we won't like everything that happens.
For instance, the same warmer temperatures that favor English ivy are also quite favorable to ivy of another sort. Research shows that rising temperatures—even the small increases seen in Kansas—and rising CO2 levels in the atmosphere are combining to expand the range of poison ivy, allowing it to be active for a longer part of the year and making it more poisonous. A walk through local parks or state lands near Merriam is now more likely to involve a brush with the less-than-friendly side of nature.
The warmer climate works in tandem with a wetter one. Merriam and much of the northern and eastern parts of Kansas have become a lot wetter, especially in the winter. The Midwest is experiencing heavier storms more often than it did in the past. Those storms can cause serious damage and cost communities some serious money. That's not all, though. Higher temperatures and more frequent downpours affect metro areas and their residents in a number of ways.