Gas Prices Drop To Lowest In 2013

CHAPEL HILL – North Carolina’s average gas price has dropped 20 cents since last month, making it the lowest price this year.

The average price per gallon in the state is now $3.27, just two cents lower than the average in the triangle area. Angela Daley, Director of Communications at AAA Carolinas, says that the price change is due to the season.

“Well the biggest factor right now is decreased demand,” Daley says. “After the end of the summer driving season, people aren’t taking those trips anymore, and so in September and October we start to see gas prices come down because demand has decreased.”

Not only has summer ended, but the Gulf coast managed to avoid any serious hurricanes, unlike in previous years.

“The other big factor right now is hurricanes,” Daley says. “We haven’t seen a major hurricane hit the Gulf, and so gas prices have really been coming down since Labor Day.  That’s the one exception that we sometimes do see gas prices go up during September and we did see that last year.”

AAA Carolina’s expects the price to continue to drop until around Thanksgiving.  During heavily traveled holidays the gas prices are likely to stabilize or slightly go up.

The Government shut-down has assisted in lowering gas prices as well since many workers aren’t commuting to jobs.  Daley says that depending on how long the government shut-down lasts, prices may continue to drop.

“Right now, the biggest factor that we’re seeing push gas prices is just overall demand down because summer is over,” Daley says. “But, depending on how long the shut-down lasts, it could push gas prices down even further.”

The last time gas was cheaper in North Carolina was December 26 2012 when the average was $3.26.  Per gallon, prices are highest in Asheville averaging around $3.36, and lowest in Fayettville at $3.21.  North Carolina’s gas prices continue to remain below the national average of $3.35.

http://chapelboro.com/news/business/gas-prices-drop-to-lowest-in-2013/

Hurricanes Part III: Frequency and Global Warming

Over the last several decades the media have consistently reported that global warming would result in more frequent and more powerful hurricanes.  The graph below shows the data for total frequency of hurricanes in the Atlantic since 1944, as well as the number of strong hurricanes, defined as category three and above.  While I have seen analyses of these data which have attempted to tease out an increasing trend, there has not been a noteworthy change in either the frequency or the strength of hurricanes during this period, despite rising air and water temperatures.

hurricane frequency

The lack of change in hurricane frequency and intensity is consistently referenced by climate change deniers as evidence that scientists have been wrong, biased, or participating in some massive conspiracy. The problem with both the news stories and the accusations of malfeasance is that there has never been a scientific consensus that global warming would result in either more frequent or stronger storms.

The inaccurate news coverage of the potential effects of global warming on hurricanes is another example of poor science reporting in the mainstream media.  I believe that this failure stems from an unwillingness to spend the time and to commit sufficient news bandwidth to grapple with complex scientific issues.  Fortunately here at Chapelboro.com, we can delve into these matters at a level of detail sufficient to understand what is really happening.

Given that one of the prerequisites for a hurricane is a water temperature of at least 79.7 °F, it is tempting to assume that warmer oceans would result in more and perhaps stronger storms.  If water temperature were the only parameter which affected hurricanes, then this assumption might turn out to be correct.  However, as is often the case with phenomena in nature, the situation is a bit more nuanced.  Let’s consider the parameters other than water temperature which effect hurricanes and how these may be impacted by global warming.

In order for a tropical cyclone – the precursor to a hurricane – to get started, a mass of cold air must be positioned above an area of warm water.  Furthermore, since the strength of the storm is dependent on the rate of condensation of water droplets in the upper atmosphere (which happens faster as the air gets colder) the initial strength of the storm is dependent on air temperature.  Therefore, to the extent that global warming is increasing the temperature of the air above the ocean, both the probability of hurricanes forming and the expected storm strengths are directionally reduced.

Another key parameter in the formation of a tropical cyclone is the need for low wind shear, which sounds counter intuitive at first.  In order for the circulating air flows of a cyclone to form and stabilize, the other air movement in the area must be limited; otherwise the cyclone never becomes “organized”.  The research I have read on the potential impact of global warming on winds in the Atlantic is inconclusive.  However, to the extent that warmer temperatures may result in stronger winds above the oceans (a reasonably likely scenario), the probability of hurricanes being formed would be reduced.

Despite not having a noticeable effect on frequency or strength, global warming is having two definite effects on hurricanes.  The warming of the oceans does result in more days per year when the surface water temperature is at or above 79.7 °F, which is lengthening hurricane season.  According to the Pew Center on Global Climate Change, the duration of hurricane season has grown by five days per decade since 1915. Therefore, in coming decades we should anticipate hurricanes starting in May and continuing through December.  Global warming is also causing sea level rise from the thermal expansion of ocean water as well as the melting of the polar ice caps.  Increases in the baseline level of the ocean reduce the amount of storm surge necessary to cause damage along the coast line, as evidenced recently in Manhattan by Superstorm Sandy.

I believe that part of the problem regarding news reports on the impact of global warming on hurricanes is that headlines about an impending series of superstorms create more of a splash than a thoughtful review of the slow steady lengthening of hurricane season and the number of inches that sea level is rising each decade.  Perhaps a hurricane on Christmas will increase the buzz-worthiness of the actual science.

There is still no sign of Barry out over the Atlantic, so he must still be working away on Vilcom Circle.  Have a comment or question?  Use the interface below or send me an email to commonscience@chapelboro.com.

http://chapelboro.com/columns/common-science/hurricanes-part-iii-frequency-and-global-warming/