Tornados and Global warming

[pscot]

Think there might be a connection? Jeff Masters does too.



Figure 4. A key ingredient for tornado formation is the presence of warm, moist air near the surface, which helps make the atmosphere unstable. On the day of the March 2, 2012 outbreak, record warm air surged northwards into the tornado formation region, setting or tying daily high temperature records at 28 airports in Louisiana, Arkansas, Mississippi, Alabama, Tennessee, Kentucky, and Georgia.

Ingredients for the tornado outbreak
This year's unusually mild winter has led to ocean temperatures across the Gulf of Mexico that are approximately 1°C above average--among the top ten warmest values on record for this time of year, going back to the 1800s. (Averaged over the month of February, the highest sea surface temperatures on record in the Gulf between 20 - 30°N, 85 - 95°W occurred in 2002, when the waters were 1.34°C above average). Friday's tornado outbreak was fueled, in part, by high instability created by unusually warm, moist air flowing north from the Gulf of Mexico due to the high water temperatures there. This exceptionally warm air set record high temperatures at 28 airports in Louisiana, Arkansas, Mississippi, Alabama, Tennessee, Kentucky, and Georgia the afternoon of the tornado outbreak (March 2.) Cold, dry air from Canada moved over the outbreak region at high altitudes. This created a highly unstable atmosphere--warm, low-density air rising in thunderstorm updrafts was able to accelerate rapidly upwards to the top of the lower atmosphere, since the surrounding air was cooler and denser at high altitudes. These vigorous updrafts needed some twisting motion to get them spinning and create tornadoes. Very strong twisting forces were present Friday over the tornado outbreak area, thanks to upper-level jet stream winds that blew in excess of 115 mph. These winds changed speed and direction sharply with height,imparting a shearing motion on the atmosphere (wind shear), causing the air to spin. High instability and a high wind shear are the two key ingredients for tornado formation.


Figure 5. The other key ingredient for tornado formation is the presence of very strong winds aloft that change speed and direction sharply with height. This change of wind imparts a shearing motion on the atmosphere (wind shear), causing the air to spin. Here, we see the upper-level wind speeds at the peak of the March 2, 2012 tornado outbreak. The jet stream can be seen as the U-shaped belt of strong winds. Jet stream winds in excess of 100 mph (deep blue colors) were present over the tornado outbreak area in this analysis of data from the NOAA North American Model (NAM) from 7 pm EST March 2, 2012. Image credit: NOAA Environmental Visualization Laboratory.

Another bad year for tornadoes in the U.S.--what's going on?
Last year's tornado season was incredibly severe, and we are off to one of the worst early-season starts to tornado season on record now in 2012. However, it is too soon to ring the alarm bells on climate change being responsible for this. The tornado data base going back to 1950 doesn't show an increasing trend in strong tornadoes in recent decades. While climate change could potentially lead to an increase in tornadoes, by increasing instability, it could also decrease them, by decreasing wind shear. I'd need to see a lot more bad tornado years before blaming climate change for the severe tornado seasons of the past two years. One thing that climate change may be doing, though, is shifting the season earlier in the year. The 5-day total of tornadoes from February 28 - March 3 will probably break the record of 131 set in 1999 for the largest tornado outbreak so early in the year. Warmer winters, and an earlier arrival of spring due to a warming climate, will allow tornado season to start earlier--and end earlier. This year's early start to tornado season is consistent with what we would expect from a warming climate. I have a more extensive article on this subject that has just been published by Weatherwise magazine, and a 2008 post, Are tornadoes getting stronger and more frequent? Dr. Jonathan Martin of the University of Wisconsin-Madison is doing interesting research on the type of situation we saw with some of the recent severe tornado outbreaks, when two branches of the jet stream, the polar jet and the subtropical jet, merge to form a "superjet." In a December 2011 interview with sciencedaily.com, he said: "There is reason to believe that in a warmer climate, this kind of overlapping of the jet streams that can lead to high-impact weather may be more frequent."

http://www.wunderground.com/blog/JeffMasters/article.html

[DCKit]

1. You use "Global Warming" in your title....

The article uses "Climate Change".

That's too big of a difference for me to give this a rec.

[immoderate]

3. This excerpt refers to "warming climate" three times.

And used "warm" as an adjective another half dozen. Is that too different?

--imm

[longship]

2. Climate v. Weather

The info in this post comes from a climate scientist (not a politician --- no matter what the deniers say). But, in spite of what others claim the only authority in science is nature herself.

This new info looks good. But it's going to take a while before the peer review catches up with this. What we don't want to do is conflate climate and weather. The former is what's happening globally over years, decades, centuries, etc. The latter is what's happening outside today.

Yes! Climate can determine weather but these connections are subject to extremely complex interactions. Anybody claiming that weather patterns are a result of global climate change had better have all their ducks in a row. One published paper isn't gonna do it.

Myself, I think this paper is going to stand up, but we all need to sit back and let the science sort itself out.

Patience, people, patience.

Thanks.

[pscot]

4. Peer review Henryville

You better believe the insurance companies are on board.

[longship]

5. Henryville is one data point

Just because a tornado wiped out a single town (or multiple towns --- which this one apparently did) is not in any way support for global warming.

But don't believe me. I'm not qualified in climate science. Rather, pay attention to what those who have studied these things for decades say. Yes, it's possible that these tornados are a result of global climate change. But, in order to say that one has to have the data to connect those facts. I just think that the connections are tenuous and no rational climate scientist would make such a claim without the data to support it.

Regardless, Henryville is one data point. Unfortunately, one data point is not sufficient to support something global like climate change.

One might ask if I think global climate change is happening. Indeed, I do. The data in support of it is overwhelming. Do I think that it is caused by human activity? Yes! There is much support for that hypothesis as well and few climatologists would doubt it. But to say that the tornados that carved their way through south Indiana and north Kentucky were caused by global warming goes too far. It very well may be. But correlation does not imply causation. Any scientist knows that.

I think it's irresponsible to make any such claims. Climate is not weather. Climate is what's happening to the world's weather over long periods of time. Weather is what's happening outside now. Weather provides the data for climate science, but one tornado does not establish a global effect like climate. That's just not how science works.

[pscot]

6. The irresponsibility lies in ignoring a vast accumulation of data points

that all point in one direction. When your kitchen is on fire, you don't put off the call to 911 because the living room's not burning yet. The scientific community is thoroughly spooked over this issue. There's a strong consensus that global warming is real and presents a huge danger to our civilization. There is a clear understanding that the cause of this warming is the vast amount of carbon being dumped into the atmosphere. You may not be convinced, but when you grandchildren are poking around in the ruins, they'll wonder what took you so long.

[longship]

7. Hmm

Here's the problem with online forums. One can make an argument and have taken as the opposite. So I explicitly say it here.

I trust the thousands of climate scientists who say that the climate is warming. I also trust them that humans are substantially contributing to this. The data is undeniable and anybody who does deny it can be portrayed as a denier.

But that does not mean that every freaking tornado has a causal relation to global warming. Correlation does not imply causation.

Now that's what these climate scientists are claiming. But one paper has no authority until it has been reviewed by other scientists. Only by the peer review process can these issues be resolved. That's how science works. In this case we have to let science to work this out.

That was the only purpose of my original post.

I'm sorry for the misunderstanding.

[pscot]

8. De nada

Sorry if I came across as a sourball. I take your point, but that line of reasoning is all too often used with nefarious intent. Peace.