Is Climate Change to Blame for Hurricane Barry?

By Chris Martz | July 15, 2019

Follow @ChrisMartzWX

As a future meteorologist, the weather is something I truly enjoy. If you ask any meteorologist that I have met, or if you ask anyone who personally knows me, they'd tell you the same thing. I always think of the weather as being the current prevailing and/or forecasted atmospheric conditions that may be good or bad depending upon my preference.

Here lately, it seems like politicians have either been confusing weather and climate, or they are just weaponizing the weather to carry out their political agendas, and unfortunately, I think the latter is more likely to be the case.

Every week, various weather events are being used as evidence of the "climate crisis." In fact, over the last two weeks alone, four specific weather events have been used as evidence of our impending doom and gloom; the European heat wave, the Guadalajara hailstorm, the flooding in D.C., and most recently, Hurricane Barry, which made landfall in Louisiana on Saturday, July 13 (Figure 1).

Figure 1. July 2019 climate crisis events.

I have already written articles explaining why the Mexico hailstorm and flooding in D.C. are not signs of the so called "ecological breakdown" (I avoided writing one for the European heat wave due to a lack of time, information, and confusion on whether or not the record was official at the time). This article is focused on Hurricane Barry, which made landfall this past Saturday in Louisiana as a weak Category 1 hurricane.

#Barry made landfall as a hurricane early this afternoon near Intracoastal City, LA. Although the center is now over land, the rainfall threat is just beginning for many locations. Continue to follow updates at https://t.co/tW4KeGdBFb and https://t.co/SiZo8ozBbn pic.twitter.com/2IFyKGpHtb

— National Hurricane Center (@NHC_Atlantic) July 13, 2019

As usual, people who have their facts backwards are using Barry as the latest "poster child" for climate change. Because people these days believe everything they hear or see on social media without taking five minutes to fact-check, they are succumbed into this dangerous way of thinking, that's politically motivated. 

Because some mainstream journalists (not all of them, there are good journalists out there) and many politicians are bombarding the public with hysterical nonsense about the weather day in and day out, people have been having anxiety and panic attacks because of even the most ordinary weather events, thinking that they are signs of human-induced climate change, when in fact they are not.

Whenever one extreme event is over with, the "climate crisis" moves somewhere else as the narrative shifts. It's not stationary.

I've created two interactive graphs which are shown below. 

The first graph shows the number of landfalling hurricanes in Louisiana by year since 1851.

(Both graphs are interactive. You can hover your mouse over the blue columns to see the year and the number of landfalling hurricanes corresponding to the year.)

As you can see by the graph above, there has been literally no trend in the number of hurricanes making landfall in Louisiana since record keeping began for the Atlantic basin (which includes the Gulf of Mexico and the Caribbean) in 1851. The most hurricanes to make landfall in Louisiana within a single season were three strikes, set in both 1860 and 1985.

The next interactive graph (below) shows the number of Louisiana hurricanes by decade since the 1850s.



As you can see by the red trendline in the graph above, there has been an insignificant decease in the number of landfalling hurricanes per decade in Louisiana.

(You can access the data yourself on the National Hurricane Center data archive.) 

Dozens of news articles such as this one and this one have surfaced, not to mention politicians, claiming that hurricanes, Barry included － and last year, Florence － are going to occur more frequently and cause more flooding in the future as the planet warms. Some articles were written prior to the storm being named by the National Hurricane Center, and others were written pre-maturely, i.e. before landfall.

Their scientific explanation roots itself in the very fact that a warmer atmosphere can hold more moisture, in addition to the fact that the amount of available moisture in the air increases as sea surface temperatures rise. Furthermore, climate activists make the case that hurricanes are starting to move more slowly as a result of a lessened temperature gradient between the poles and tropics (polar amplification) which slow the winds that move tropical cyclones, and as a result, dump out more rain on any given area impacted by a landfall.¹

I’m praying for New Orleans and its resilient people as they brace for major flooding from Tropical Storm #Barry. Climate change is an existential threat—and we must take action now.

— Elizabeth Warren (@ewarren) July 12, 2019

The problem with attributing [at the very least Gulf of Mexico] hurricanes on climate change is that the sea surface temperatures in the Gulf have seen very little change since 1900. A little outdated I know, but recent sea surface temperatures in the Gulf are actually a little bit cooler than they were during the 1930s and 1940s (Figure 2).² 

Figure 2. Monthly Gulf of Mexico sea surface temperature anomalies from HADSST2 from 1900 to 2011. - Bob Tisdale.

But here's what they don't tell you. 

Tropical cyclones require many more ingredients to develop than warm sea surface temperatures － preferably at or over 80°F. The Gulf of Mexico's sea surface temperatures are plenty warm enough every year to produce hurricanes of any size and/or intensity. 

Most tropical cyclones can be traced back to tropical waves or cyclonic circulations that originally formed off of the coast of Africa － or elsewhere. Such disturbances are pre-existing conditions and may intensify into an organized circulation that is sustained by warm sea surface temperatures. 

If tropical storm systems, like hurricanes or tropical storms run into wind shear, the storm will fall apart as it becomes tilted vertically, which consequently draws in dry air, suppressing convection.³

Wind shear is generally higher in the Atlantic basin during El Niño events, when there's warmer than average sea surface temperatures in the Equatorial Pacific.³ During La Niña events, wind shear in the Atlantic, Caribbean, and Gulf tends to be lower. Both 2005 and 2017 were La Niña years (Figure 3), and were very hyperactive seasons in the Atlantic.⁴ 

Figure 3. La Nina years.

With El Niño fading currently (Figure 4),⁵ I'm actually a bit concerned that we might see an uptick in tropical development in the Atlantic, Caribbean, and Gulf of Mexico in the coming weeks and months.

Figure 4. CDAS Nino 3.4 time series.

A result of the Pacific Decadal Oscillation (PDO) undergoing a phase change into its warm mode in the late 1970s, is more El Niño events.⁶ Because of this, higher wind shear in the Atlantic basin likely contributed to the record "11-year hurricane drought" in the United States lasting from 2006 through 2016 (in between the active seasons of 2005 and 2017), when there were no major hurricane strikes (Category 3+) in the Continental United States.

It's a fair argument to make － and I would generally agree － that natural variations in Earth's climate, changes potentially caused by man like land use, or some combination of the two could alter the intensity and/or frequency of weather patterns and extreme events like heat waves, tornadoes, wildfires, and tropical cyclones. However, the notion that a warming climate － caused by whatever reason － worsens such events is not supported by observational data. 

In fact, numerous studies and scientific reports have tried finding a linkage between recent human-induced climate change and tropical cyclones, and results have been inconclusive on the matter. 

For instance, the IPCC openly admitted in their 2013 report that tropical cyclones can not be blamed on climate change. In IPCC AR5 (2013), they stated:

"Globally, there is low confidence in attribution of changes in tropical cyclone activity to human influence. This is due to insufficient observational evidence, lack of physical understanding of the links between anthropogenic drivers of climate and tropical cyclone activity, and the low level of agreement between studies as to the relative importance of internal variability, and anthropogenic and natural forcings."

The National Academy of Sciences (NAS) also says that there is low confidence in attributing tropical cyclones on anthropogenic climate change (Figure 5).⁷

Figure 5. Climate change and extreme weather. - National Academy of Sciences (NAS).

So, why are people blaming hurricanes on man-made climate change? It's because they have no clue what they're talking about and are not interested in facts. It's that simple.

To blame or link extreme, life-threatening weather events, like hurricanes on man-made climate change while the storm is ongoing, is USELESS information to those who may be in the storm's path. The last thing they, or forecasters like me are worried about is whether or not increases in a trace, odorless gas in the atmosphere slightly worsened a storm headed their way. 

It's one thing for someone to link a single extreme weather event to climate change after the event is all said and done with, assessments are made, and statistics are looked over. It's another to write articles pre-maturely and assume things based on scientific illiteracy.

REFERENCES

[1] Skilling, Tom. "Why do some hurricanes move slowly?" WGN-TV | Chicago's Very Own source for breaking news, weather sports and entertainment. July 8, 2017. Accessed July 14, 2019. https://wgntv.com/2018/07/08/why-do-some-hurricanes-move-slowly/.

[2] Tisdale, Bob. "Are Gulf of Mexico Sea Surface Temperature Anomalies Near to Record Levels?" Bob Tisdale - Climate Observations. April 30, 2011. Accessed July 14, 2019. https://bobtisdale.wordpress.com/2011/04/30/are-gulf-of-mexico-sea-surface-temperature-anomalies-near-to-record-levels/.

[3] Sosnowski, Alex. What is wind shear and how does it impact hurricanes, other tropical cyclones?" AccuWeather. Accessed July 14, 2019. https://www.accuweather.com/en/weather-news/what-is-wind-shear-and-how-does-it-impact-hurricanes-other-tropical-cyclones/70007871.

[4] Null, Jan. "El Niño and La Niña Years and Intensities." Golden Gate Weather Service Accessed July 14, 2019. https://ggweather.com/enso/oni.htm.

[5] Cowan, Levi. "CDAS Niño 3.4 Index." Tropical Tidbits. Accessed July 14, 2019. https://tropicaltidbits.com/analysis/ocean/nino34.png.

[6] D'Aleo, Joseph. "Ocean Multi-Decadal Changes and Temperatures." Accessed July 14, 2019. http://icecap.us/docs/change/OceanMultidecadalCyclesTemps.pdf.

[7] "Climate Change and Extreme Weather." Penn State Department of Meteorology and Atmospheric Science. Accessed July 14, 2019. https://www.e-education.psu.edu/meteo3/l10_p9.html.