Native birds vanishing, crab shells thinning and ice melting under polar bears may not cause alarm in the Midwest, but flooded basements, the threat of West Nile virus, and higher fruit and vegetable prices are side effects that make climate change hit closer to home.
Climate change—often linked to increased accumulations of greenhouse gases that hold in the earth's radiated heat—may contribute to all of these things and more. Scientists at the Purdue Climate Change Research Center (PCCRC) are studying the causes and long-term implications of new weather patterns and seeking management strategies for the fluctuation, which is already being felt worldwide.
No crystal ball
The center includes about 30 researchers who are dedicated to finding the most accurate methods of predicting future climate and the resulting environmental and economic impacts and developing ways to mitigate and adapt to the changes. The center extends beyond Purdue through partnerships with scientists from other universities and state, federal and international agencies.
“One of the things that we see clearly from the past 20 years or so is that climate is more variable,” says Rich Grant, Purdue environmental meteorologist. “We don't necessarily know that the variability is because of what man has done, but we have more frequent big floods and other extreme weather changes.”
For example, four hurricanes struck Florida in the span of a few months in 2004, causing more than $40 billion in damage and killing 130 people. The storms also devastated several Caribbean islands, killing thousands throughout the region. Indiana, along with other Midwestern states, is still reeling from January floods that destroyed hundreds of homes. This comes only a year-and-a-half after raging floodwaters caused nearly $235 million in damage in the state in 2003.
Climate change prediction is difficult because of the many natural and manmade factors that affect it, such as technological developments, cloud cover changes, solar radiation, vegetation, soil moisture, volcanic eruptions and population. “The environment is a complicated system,” says Grant, who studies the interactions of solar radiation, evaporation, ultraviolet rays, and tree and crop transpiration, as well as the spread of crop-damaging insects and diseases. “We only understand a relatively small part of it.”
While no single event is responsible for global climate change, changes in atmospheric composition can spawn change in climate and vice versa, says Paul Shepson, PCCRC interim director. Greenhouse gases, including carbon dioxide, methane, ozone, nitrous oxide and manmade chemicals called “chlorofluorocarbons,” play significant roles in climate change.
For instance, if a forest is cut down, carbon dioxide increases in the atmosphere because the trees aren't using it. The trapped heat raises soil and water temperatures, which cause polar and glacial ice to melt and permafrost to thaw. These factors contribute to more warming, lowland flooding, displacement of animals and changes in ocean currents. The currents, or ocean conveyor, influence air temperatures, precipitation and worldwide water distribution. Such climate shifts due to warmer temperatures someday might even entail moving corn production to Canada and switching the Corn Belt to sorghum.
Scientists say that climate changes are already occurring. Global annual average temperatures have risen an average of 1 degree Fahrenheit over the last century, according to the National Research Council (NRC). This may seem trifling, but with atmospheric carbon dioxide expected to double by 2100, the NRC predicts that temperatures in most areas will jump another 4-7 degrees, the same amount that has occurred in the Arctic over the past 50 years.