Roger Pielke, Jr. is a professor of environmental studies at CU-Boulder. He helped found the school's Center for Science and Technology Policy Research. He's also the author of several books and he's a particularly polarizing figure in the world of climate change.
ThinkProgress - a liberal-leaning political blog had this to say about him:
Roger Pielke, Jr. is the single most disputed and debunked person in the entire realm of people who publish regularly on disasters and climate change.
Foreign Policy Magazine included him in their list of controversial climate scientists:
For his work questioning certain graphs presented in IPCC reports, Pielke has been accused by some of being a climate change "denier." Meanwhile, for his work on adaptation, he has been accused by others of being an "alarmist."
Given the way people talk about him, I half-expected red, glowing eyes or a forked tongue when he came to speak at our weekly seminar. Neither proved true - he was a perfectly affable guy who had some pretty interesting things to say, starting with a great explanation of the difference between climate and weather. It's something that a lot of people don't understand, including me, and his example was one of the best I've heard, so I'm going to attempt to replicate it here:
Think of a regular deck of 52 playing cards, like one you'd use for a game of blackjack.
Each possible hand - and there are a lot of them - represents a weather event. Sunny and 70. Cloudy with gusts of wind. Steady drizzle all day.
A blackjack - that is a hand totaling 21 - is an extreme weather event, like a hurricane or a tornado.
Together, all those weather events - that universe of all the possible hands that can be dealt - are equivalent to climate.
With those standard 52 cards, the card players (scientists and, to a lesser degree, us) have a pretty good idea of how things are going to play out. The make-up of hands (the weather) may vary tremendously - you might get three great hands in a row and then go on a horrible losing streak - but overall, there's pretty good information on where you'll be after you play every hand possible.
So now let's say that something changes in the deck - the climate - and another card is added. That card represents a new element (i.e. increased greenhouse gases). But we don't know how the deck has been changed, so (unless we are VERY good card players) we're not going to see how that card alters the game for a long time.
That's what's happening now. The deck has been altered but we still don't know what the implications will be in the long-term. It will take decades of data before we have that information - we can't just base it off of recent weather events. A few cold winters (i.e. bad hands) does not indicate an overall cooling trend.
And for another helpful explanation, check out this video from a Norwegian television series about taking a dog for a walk.
Ok, so now we have a better grasp of climate and weather (I think).
Pielke also talked about extreme weather (which would be the equivalent of a 21 on blackjack), like hurricanes and tornadoes. Claims that these extreme weather events are due to climate change aren't backed up by the facts. Data from the National Oceanic and Atmospheric Administration (NOAA) show the power and frequency of hurricanes have actually declined by 20% since the early 1900s. You can't look at those numbers and draw the conclusion that climate change means stronger, more frequent hurricanes - the evidence just isn't there. We have to keep playing our card game to see what information comes out of it - more hurricanes? Fewer hurricanes? Drought? Sharknadoes? We'll have to watch how the game evolves.
Activists were none too pleased by Pielke's arguments - leading to claims like the ones above, calling him a denier. However, Pielke does believe climate change is happening and that humans are contributing to it. His argument is that using extreme weather events as a way to illustrate climate change is incorrect. There are far better ways to make this point, namely temperature, precipitation and sea level - all of which are measurements that we can take daily over long periods of time to see what the overall trends are and what we can expect going forward. But those aren't as exciting and they don't grab the public's attention in the same way.
Activists, understandably, want people to take action now. Tying hurricanes and other extreme weather events to climate change provides a concrete way of saying, "Look how dangerous this all is - we need to do something!" But it seems like it's important to present the facts - to play with the hand they've been dealt, if you will. Otherwise, they risk losing the public's trust when their opponents can show they've been pushing bad information. And that will make it much harder to accomplish anything, now or in the future.