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!