I want to quickly mention two interesting items that crossed my desk. First is a study in Nature that looks at changes in extreme weather patterns between 1979 and very recently, the other is a study of how media has been addressing climate science denial among presidential candidates.
Evidence that global warming is intensifying extreme weather
First, the changes in weather. Human caused greenhouse gas pollution has resulted in important changes in key factors that affect the weather. The simplest (but not complete) explanation is probably this. Overall patterns of air circulation (including the moisture that is in the air) are patterned by two major facts. One, is that the Earth is spinning, the other is that the Sun's energy is effectively greater near the Equator than on the poles. These factors cause the Earth's atmosphere to be organized in a system of trade winds and jet streams. As the Earth has heated up, the Arctic, for various reasons, has heated up more than most other regions. This has caused a reduction in the difference between tropical (equatorial) heat and polar heat, which in turn, has changed the trade winds and jet streams. The most obvious change seems to be a slowing down of the Polar jet stream, an increase in the waviness of that jet stream, and also, a stalling of those waves, so they sit in one place for a long time. These changes have resulted in things like Alaska being extraordinarily warm, the so-called "Polar Vortex" freezing out the US east of the Rockies two years in a row, extreme rain events such as those that affected Calgary, Boulder, and other areas, snow in Atlanta, etc. Similar effects have occurred across Eurasia as well.
The recent study looks at what is happening in the atmosphere. John Abraham has written the study up in very understandable terms in The Guardian, where he says:
...the authors focused on pressure levels up into the atmosphere (heights of approximately 5 km) from 1979 onwards. Those patterns gave information about atmospheric circulation...
...What they found is that most regions have seen increases in summertime warm temperatures in the past three decades. Furthermore, they found that in some regions, a large part of this trend is due to the increases in anticyclonic circulation and atmospheric blocking. The blocking that has been associated with extreme swings of weather (bringing very warm weather to the Western USA and simultaneous cold weather to the east for instance).
The authors show that ... in some cases the circulation changes has led to extreme cold outbreaks in some regions. What has happened is that the arctic front, which typically confines cold weather to the Arctic region, has undulated sufficiently to allow cold-air breakouts to the south. Think of the polar vortex from last year.
These findings support the commonly-heard term that has emerged in the past few years of “weather whiplash - wild swings from one extreme to another. Importantly, the authors show that the trends are “statistically significant” and are unlikely just random occurrences.
This work supports a number of other recent studies suggesting that the "Storm World" we have been expecting with global warming is here, and increasing in its storminess.
How The Media Is Covering Presidential Candidates' Climate Science Denial
The second item is from Media Matters. The report indicates that the media frequently fails to fact check presidential candidates when they say incorrect things about climate change. Media Matters paints this situation in a very negative light, noting that a large percentage of the time major media outlets fail to call these candidates when they get climate change wrong. I put a graph from their report at the top of the post.
I understand why Media Matters puts this in a negative light, because it is in fact appalling that the media are so bad at this. But when I saw the numbers I saw a glass that was (about) half full rather than half empty. Going back just a year or so, major media wasn't even doing this much fact checking, preferring rather to use the sensationalism that derives from a false balance than to actually look at what elected officials are saying. So when Media Matters says, "43 Percent Of Newspaper Coverage Failed To Note That Candidates' Climate Statements Conflict With Scientific Consensus," I think, "wow, that's an improvement!
Any study on coverage of the candidates Climate Support (or non-denial) comments?
I'm sure there will be. We are already seeing some variation among the Republicans, for the first time (almost). It will be interesting to see if candidates in the GOP who admit that AGW is real and important are driven from the herd.
It's timely to comment on the effects of warming on the jet stream. I've bumped into quite a few deniers recently who use instances of extreme cold to "prove" that global warming is not occurring. The simple fact is that the physics of atmospheric/oceanic warming are such that counter-intuitive consequences occur. What these deniers are refusing to acknowledge is that some consequences are counterintuitive - but this refusal to admit is not actually a refutation of the science.
In the end their whole premise is based on their intuition, and it is a classic demonstration of why we have the scientific method with experimentation and data collection/analysis rather than plain old 'common sense' as a way to objectively understand the universe.
It would be worth noting Abraham's quote in his previous article from the Trenberth et al paper.
The climate is changing: we have a new normal. The environment in which all weather events occur is not what it used to be. All storms, without exception, are different. Even if most of them look just like the ones we used to have, they are not the same.
The point being, talking about "attribution" needs to be done very carefully to avoid providing another source of confusion and potential misrepresentation.
There are no observed "natural" variations if by that one means "variations that would have occurred absent the presence of anthropogenic CO2."
The simple fact is that the physics of atmospheric/oceanic warming are such that counter-intuitive consequences occur.
Agreed, but how to package this idea in a way that will penetrate the consciousness of the average tv news consumer? Not that they want to know about this stuff, but it's the thought that counts.
Regarding these difficulties, Greg had a blog post dealing specifically with this subject:
It's often worse than "they don't want to know". As Upton Sinclair observed, “It is difficult to get a man to understand something, when his salary depends upon his not understanding it.”
Yes and I think Sinclair was overly optimistic. I'm going for a reverse statistical effect: there's no reason to think any one viewer will change his or her mind, but maybe the weight of millions of tiny suggestions on tv will push the general sentiment towards "We need to do something."