Columnist Jack Kelly recently asked "Is Global Warming a Hoax?" (Pittsburgh Press, April 9).
As a scientist, that's like hearing someone ask "Is gravity a hoax?"
Of course it isn't.
When it comes to global warming, scientists know carbon dioxide from burning coal and gas and from destroying tropical forests has led to dramatic warming and changes to rainfall patterns around the world. Our own National Academy of Sciences -- and equivalent institutions in dozens of countries -- agree that climate change is human-caused and disrupting our way of life.
A better question to ask is, "What does global warming mean for Pennsylvania?"
In 2008, I conducted a scientific review to help answer that question. I found that Western Pennsylvania's summers would be more like Kentucky's by the end of the century if we reduce our heat-trapping emissions. But if our emissions continue to climb at current rates, summers in Western Pennsylvania would be more like Alabama's.
Those shifts in climate could lead to a rise in days over 90 degrees that strain public health, especially in urban areas like Pittsburgh; disruptions in the growing season for important crops like sweet corn and apples; increased heat stress for dairy cattle; and a decline in the length of the snow season for ski resorts and snowmobilers.
These findings make us ask other questions: Do we want to keep burning so much coal and oil? And how should we prepare for the changes that are already locked in?
These questions can make some people uncomfortable. They sometimes make the mistake of rejecting the science rather than dealing with its implications.
But as the astrophysicist Neil deGrasse Tyson likes to say, one of the amazing things about science is that it remains true whether or not you believe it.
This past decade was hotter than the previous one -- and the one before that. The surface of the land and oceans continues to warm, as does the deep ocean. As the ocean warms and expands, glaciers shrink, currents shift and sea levels rise. All told, sea level along the mid-Atlantic coast has risen, on average, about 8 inches in the past 100 years.
Mr. Kelly claimed that global warming can only be found inside computer models, which scientists use to estimate the effects of future emissions on our planet. But climate change is all around us, from warmer springs to more intense heat waves to the destruction from Sandy's storm surge, which was made worse by warming, rising seas.
Mr. Kelly also discussed a scientist at the University of Oregon who found that modern temperatures are quite warm compared to the past. This is not a controversial finding among scientists, but Mr. Kelly goes so far as to accuse him of making it all up. Such baseless attacks on scientists shouldn't be a part of our public discourse on climate change, especially when we have so many other important things to talk about.
Thankfully, Pennsylvanians are already talking about how to deal with climate change. The state's climate-adaptation plan calls for integrating what we know about climate change into decisions the state makes about water supplies, heat stress, conservation and tourism. The city of Pittsburgh is also working with businesses, universities and other institutions to find ways to reduce emissions and manage climate change.
More people need to follow Pennsylvania and Pittsburgh's lead and ask the right questions about climate change. The answers we come up with can make our communities stronger, healthier and safer for generations to come.
Melanie Fitzpatrick is a climate scientist at the Union of Concerned Scientists.