Showing posts with label tornado. Show all posts
Showing posts with label tornado. Show all posts

Tuesday, June 4, 2013

The Tornado Connection to Climate Change


By  Paul Beckwith, B.Eng, M.Sc. (Physics),
Ph.D. student (Climatology) and Part-time Professor,
University of Ottawa

"In 2012, 93 percent of natural catastrophes were weather-related disasters. The United States was seriously affected: it accounted for 69% of overall losses and 92% of insured losses due to natural catastrophes worldwide." ~ World Watch Institute

"America has some of the wildest weather on the planet, and it turns out those extremes – which run from heat waves and tornadoes to floods, hurricanes and droughts – carry a heavy price tag." ~ theguardian

3D look at the Moore Oklahoma thunderstorm and tornado, up to 50,000 ft. Image by Tony Petrarca
from Tony's Pinpoint Weather Blog showing the funnel touching the ground just outside of Moore. 
The mega-storm that generated the massive cyclonic system that passed over the central U.S (from May 18th through May 20th) spawned many storm systems and severe tornadoes. In Oklahoma, it took less than 1 hour for a thunderstorm system to develop into a full-blown 3 km diameter tornado of the highest size/strength (EF5). As you know, this tornado caused total devastation along a swath greater than 30 km long and about 3 km wide in the southern part of the city. Two schools and a hospital were destroyed resulting in heavy loss of life.

The actual tornado tracked through the most built up part of the city and had a length of 6.22 km (Image 2). As bad as this was, if the tornado had tracked further north by about 10 km, the path length through the built-up part of the city would have been about 28 km and likely would have resulted in FOUR TIMES MORE DAMAGE.

The high altitude jet stream guided this storm directly over Oklahoma City and was a key ingredient responsible for the extremely rapid development of the tornado witnessed. Unfortunately, the location, strength, waviness, and behavior of the jet stream is changing as a result of rapid climate change. You can get use to more “Climate Bomb” extreme weather events – there is nothing to be surprised about here.

Greenhouse gas emissions from humans have warmed the planet since about 1850; the warming rate has stepped up a notch over the past several decades, and even more so now with ‘feedbacks’ kicking in big time.

There is less snow cover on the land over northern Canada, northern Eurasia and Siberia, and there is less sea ice over the Arctic Ocean. The snow and ice reflects greater than 80% of the incoming light from the sun back into space keeping these areas colder. With less snow the dark land is uncovered and with less sea ice the dark ocean is uncovered. These both reflect much less light; only about 20% and 10% respectively. The rest is absorbed and heats the ground and sea. The melting ground is releasing methane; the warming sea heats the sea floor and that warming releases more methane. Thus, parts of the high Arctic are warming at 5 to 6 times the average global rate. The equator temperature does not change as much (even seasonally the change is only about 3°C over the year). Thus, the temperature gradient between the equator and Arctic is greatly reduced.

By basic physics and meteorology, this reduced equator-pole temperature difference slows the west to east wind component. Fast jet streams circle the earth from west to east; as they slow they become much wavier and travel much more northward and southward. Regions north of the wavy jets are cold and dry (air source is cold Arctic) while regions south of the wavy jets are hot and moist (air source is equatorial marine regions). The jet is thus an intersection of these two different types of air masses (with cold fronts and warm fronts, respectively). The large local temperature gradients give rise to large pressure gradients resulting in extreme (and very unstable) weather regions.

May 20, 2013 Moore, Oklahoma tornado
Since the wave troughs carry cold air very far south and the wave crests carry warm moist air far north, the frontal temperature gradients are larger under climate change then they were before and thus the storm magnitudes are now larger. That’s why I wrote earlier that we shouldn’t be surprised.

Global warming also brings greater ocean evaporation and warmer air can carry more water vapor – in fact, in the last 3 decades or so there has been a 4% increase in atmospheric humidity. When this water vapor condenses to forms clouds, energy is released. Greater energy in the atmosphere thus fuels more violent storms, and Climate Bombs are born.

The Oklahoma tornado is just another example of the global ‘weirding‘ that we are seeing. Our reference frame is the “old climate”, in which the equator-polar temperature gradients are smaller, but the local frontal temperature gradients are larger. In our “new climate” (in which there is much less sea ice in the Arctic) this type of tornado will be much more probable — at least while we abruptly transition from the “old” to the “new” and unfamiliar climate.

Our future is a world with much warmer global temperatures. Paleoclimate records show temperature rises of 6 to 10°C within two decades have occurred many times in the past over Greenland; in one case the rise was 16°C. I see no reason why this will not occur again.

Put your seat belt on . . . oil profits can’t save you from Climate 2.0.


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- Climate change causing US wildfire season to last longer, Congress told

Wednesday, January 30, 2013

Extreme Weather Warning


Above image is from NOAA Storm Prediction Center, with Convective Watches in red. 

Below, storm reports, from the same site. 


For an update on the current situation in your area, see:

Meanwhile, in Canada, Paul Beckwith gives more background on 'Our rapidly changing climate and weather'.

Paul Beckwith
Part-time professor, PhD student (abrupt climate change), Department of Geography
Location: University of Ottawa, in the hub next to the university bookstore
Description:
Not a typical January in Ottawa. 10 degrees C for several days one week; -30 the next; followed by 10 the one after that. Why?

Normally the high altitude jet streams that circle the planet are predominantly from west to east with little waviness. Weather is cold and dry northward of the jets (Arctic air sourced) and warm and wet southward (moist tropics and ocean sourced). Now, and moving forward, the jets are extremely wavy and as the crests and troughs of the waves sweep by us each week we experience the massive swings in temperature. The extreme jet waviness is due to a very large reduction in the equator-to-Arctic temperature gradient caused by an exponentially declining Arctic reflectivity from sea-ice and snow cover collapses (which causes great amplification of Arctic temperatures). Additional amplification is occurring due to rapidly rising methane concentrations sourced from sea-floor sediments and terrestrial permafrost.

Observed changes will accelerate as late summer sea-ice completely vanishes from Arctic within a few years. Largest human impacts will be food supply shortages and increases in severity, frequency, and duration of extreme weather events.

In the video below, by Gzowski Films, Paul Beckwith speaks on our radical weather patterns.