Climate Change and More Weather Extremes

Crossposted with TheGreenGrok.

The American public may have it right this time.

Wacky Weather

Weather is fundamentally strange -- as we go from one season to the next, it's hard to know what to expect. Long-range weather forecasts can help a bit, but it's still a crapshoot when trying to suss out, for example, whether we're headed for a hot or mild summer this year. Even so, we seem to have been subjected to especially bizarre and extreme weather over the past two to three years. Examples include:

• The historic drought and record-breaking heat (and resulting wildfires) that began in 2010 across Texas and the Southwest.
  
• The extreme flooding along the Mississippi River in 2011 (attributed to persistent rain and snow melt) during which parts of the Ohio River Valley received almost 300 percent its normal rainfall amounts.
  
• "Snowmageddon" of 2009-2010 when blizzards with record-breaking snowfall hit the East Coast. (More on weather extremes.)

Scientists Cautious About a Global Warming Link

Are these recent events just a bump in the road of weather variability or part of a long-term trend?  Are they simply part of the natural variability of our climate or one of many manifestations of global warming?

These are difficult questions to answer. The first question is challenging because weather is so variable and that variability makes it difficult to tease out a long-term trend from all the noise of natural variations.

Nevertheless, scientists love a challenge and have been trying to answer these questions. A growing number of studies do in fact indicate that some aspects of the weather have been increasing in intensity over the past few decades.

For example, a 2010 study of trends in European rainfall events between 1950 and 2008 found that there has been a shift toward longer events and that the tendency with the longer events has been for more intense rainfall. A study from last year found that Northern Hemisphere precipitation in general is becoming more intense. Studies examining heat and drought have found that dry periods are increasing in number and getting longer and that extreme summer temperatures are occurring more often in the United States.

(In a related work just published in the journal Science, Paul Durack of the Lawrence Livermore National Laboratory and colleagues report that trends in the salinity of surface ocean water point to a decadal intensification of the water cycle such that wet places are becoming wetter and dry places are becoming drier.)

The second question is even more difficult to answer: the climate is a measure of the long-term average state of the atmosphere, and so it is virtually impossible to attribute any single weather event, no matter how extreme, to climate change. Nevertheless, inferences can be made, for example, using probabilistic arguments. And for the most part these approaches do in fact indicate that global warming could very well be a significant contributor to many of these events. But note all the caveats: "could... be," "significant," "many." We just can't do better than that.

Even so, a Yale-George Mason poll suggests that a significant number of Americans are pretty well convinced.

John Q. Public Weighs In

Scientists have been known to lament over the fact that the American public just does not seem to understand what's going on with the climate. While virtually all of the major scientific associations including the U.S. National Academy of Sciences, have concluded that global warming is real, is largely caused by human activities, and is a serious enough problem deserving of concerted action to mitigate, a significant percentage of Americans remain unconvinced or unconcerned.

But the recent Yale-George Mason poll suggests the tide may be turning: "three out of four U.S. voters favor regulating carbon dioxide as a greenhouse-gas pollutant," as Reuters reported on the survey. And in the case of extreme weather, it appears that the American public may be out in front of the scientists. According to the poll,

• By a margin of more than two to one (52 percent versus 22 percent), Americans say the weather in the United States has been getting worse, not better.
• About half of all Americans (43-53 percent) say that heavy rains and heat waves and droughts have become more common in their local area over the past few decades.
• A large majority of Americans (59-72 percent) believes that global warming made recent high-profile extreme weather events worse.
  

So which do you find more bizarre? The apparent trend in weird weather or the swing in public opinion about climate change? And which do you think is more likely to hold?

 

Follow Bill Chameides on Twitter: www.twitter.com/TheGreenGrok

Comments

[StephenBP]

07:52 AM on 04/30/2012

So what is on the plate today? Evidence of more extreme weather? Cautious examination of suggestive trends? And the response?

“Its been bad before. This is nothing new”. I remember my dad calling my neighbor an alarmist when he said that the town was washing away one rainy summer morning. So we all drove down to town and… son of a gun… town had just been washed away….we saw houses and trailer trucks floating right down the river…

“CO2 is saturated”.. Where have I heard that before? Isn’t that what the fossil fuel barons said to Svante Arrhenius at the turn of the twentieth century? Then why are the amounts of energy measured at infrared wavelengths associated with CO2 getting more and more attenuated every year?

“Freeman Dyson says so!”. Please. Freeman Dyson is the genius who wants to power a spaceship by strapping atom bombs to the bottom and setting them off. That sounds very practical, doesn’t it?….Funny, but no other physicists are taking him seriously this year. Would you volunteer to take a trip to Uranus powered by an atom bomb under your.......seat?

Thanks but I will wait for something a wee bit more practical.

[George Skulsky]

05:09 PM on 04/29/2012

Madness, Either the greens & Bill don't know how to read or check records but we have had worse extreme weather & natural related incidents in the past, way way back in recent recorded times, plus all the geological analytical information recorded by scientists over the past 500 years. Sad that we only have a life of approx 85 years because everyone grows old & dies as they have with Natural Climate change that has been ongoing since the beginning of time. Why is there an equatorial forest being exposed in the arctic?

[lbsaltzman]

10:42 PM on 04/29/2012

The fact of natural climate change in the past in no way negates that humans are unnaturally changing the climate now. It might also be pointed out that you only know about climate change in the past because of the work of many of the same scientists who have uncovered anthropogenic climate change. If you accept the scientists are right on natural climate change it is not logical to use natural climate change as "evidence" to disprove anthropogenic climate change.

[trumphent]

12:59 AM on 04/30/2012

Plate tectonics is not your friend.

[fumes]

05:30 PM on 04/27/2012

the greenhouse effect is saturated..

any more CO2 is just plant food

[Icarus62]

07:12 PM on 04/27/2012

The greenhouse effect is far from saturated. Think about it: The atmosphere gets thinner with height, so regardless of how much greenhouse gas there is in the atmosphere, there has to be a level at which the concentration is so low that the infrared radiation escapes to space. That is then the effective radiating layer of the atmosphere (what you would see if you were, say, standing on the moon with an infrared detector pointed at the Earth).

If you increase the concentration of greenhouse gas, then that must increase absorption of infrared at this top layer, so then the effective radiating layer becomes higher, and therefore colder, and the planet must warm up until infrared radiation from the surface increases enough to balance the enhanced greenhouse effect.

The logic is undeniable, because the incoming solar radiation remains the same (240W/m²) and if the planet is absorbing the same amount of energy but radiating less, it *must* necessarily warm up. Agreed? This is just basic unarguable radiative physics... and you can't dispute fundamental laws of physics.

[fumes]

11:24 PM on 04/27/2012

''...and you can't dispute fundamental laws of physics.''
-------------
i can't..

but Dyson, Giaever and Happer can..

and do

[trumphent]

07:33 PM on 04/27/2012

Good luck with that hypothesis. You are going to need it. The Greenhouse Effect is logarithmic. I suggest you put down the exhaust pipe and take a deep breath of relatively fresh air for the first time in a long time.