By Jerry Schnoor

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Is there a congruent connection between the ravages of Hurricane Sandy and the U.S. drought of 2012? How can we reconcile the “weird weather” that we are seeing across the planet?

Although a warming climate manifests itself in many different ways, the changes we are experiencing now are totally consistent with a forced warming of the planet by greenhouse gases. Globally, arctic ice is melting, Antarctic ice shelves are undercut by warmer ocean currents, sea level is rising, the sea surface temperature has warmed 1 degree Fahrenheit, and the planet averages 1.4 degree Fahrenheit warmer than 100 years ago.

In Iowa, our past 50 years have been wetter and warmer (due to warmer nights and winters) compared to the previous 50 years (Climate Change Impacts on Iowa 2010, www.cgrer.uiowa.edu). Extrapolation of our past record would indicate more precipitation and a warmer future in decades to come. We might expect flood years like 1965, 1993, 2008, 2010 and 2011 to become more frequent.

On the other hand, climate models predict Iowa will become warmer and drier, more like the drought years of 1936, 1956, 1988 and 2012. These models project a pattern more consistent with this year’s drought, and indicate that Iowa will be considerably drier throughout much of the 21st century.

Prudence would dictate that we prepare for more extreme weather, both floods and droughts, in the future.

Was the drought of 2012 caused by human-induced climate change? No one can say for sure that a single event was caused by global warming, but there is clear statistical evidence that extreme high temperatures are occurring disproportionately more than extreme low temperatures.

The only thing that we know with some certainty is that it will be a warmer planet in the future due to the strong accumulation of greenhouse gases, which absorb the Earth’s back-radiation much like rolling up the windows of your car on a sunny day. If greenhouse gases from fossil fuel emissions continue unabated, Earth will grow continuously warmer for decades and centuries to come. Extremes in temperature and precipitation are likely to become more frequent, too, based on the increasing variability we have seen in the past and projected by models.

But the good news is that we can reverse climate change by acting now. We must level off global emissions now and achieve steep cuts by 2050.

In Iowa, we can build a new green economy from wind power, solar energy and biomass resources. As chair of the Iowa Climate Change Advisory Committee in 2007 and 2008, I saw firsthand a consensus emerge among Iowans on actions to save energy, stimulate the economy, and reduce greenhouse gas emissions (http://www.iaclimatechange.us/).

Those options are still available today:

l Expand renewable energy sources such as wind and solar.

l Use Iowa biomass to co-generate power and serve as a feedstock for cellulosic biofuels.

l Save energy by weatherizing homes and making appliances/motors/fans more efficient.

l Capture energy at landfills, wastewater treatment plants and animal-feeding operations through anaerobic digestion and microturbine electrical generation.

It’s a teachable moment. The tendency to dismiss the current drought and climate change as just another manifestation of variable weather is dangerous. It fails to acknowledge the clear and present danger of accumulating greenhouse gases and the changing climate it will cause.

We can adapt our infrastructure to more extreme weather, but we must also help to mitigate climate change by reducing our emissions. A transition from the fossil-fuel age to the renewable-energy era can provide an engine for economic development for Iowa and the country while addressing a very serious problem for future generations.

Jerry Schnoor, a professor at the University of Iowa and Co-Director of the Center for Global and Regional Environmental Research, chaired the Iowa Climate Change Advisory Committee and served as a contributing member to the Iowa Climate Impacts 2010 report. Comments:jschnoor@engineering.uiowa.edu