Hurricane Katrina was one of the worst natural disasters in a generation. On August 29, 2005, Katrina slammed into the Gulf Coast near New Orleans, Louisiana. This massive storm measured about 400 miles in diameter.
Hurricane intensity is measured by the Saffir-Simpson Hurricane Scale, based upon sustained wind velocity. Maximum sustained winds of 74 mph are required for a storm to be designated as a hurricane. Category 1 storms (74-95 mph winds) typically produce modest damage. The strongest hurricanes on the Saffir-Simpson scale are designated Category 5, with sustained winds exceeding 157 mph. Katrina became a Category 5 storm as it crossed the Gulf of Mexico with sustained winds reaching an astonishing 175 mph. The storm’s intensity somewhat lessened by the time it made landfall to Category 3 with winds of 125 mph.
Thanks to modern weather satellites, meteorologists were able to warn people along the Gulf Coast that a major storm was imminent. The day before Katrina arrived, New Orleans mayor Ray Nagin issued a mandatory evacuation order – the first in the city’s history. About 80% of the city’s population heeded the evacuation order. However, many people were unable or unwilling to vacate the area. The National Weather Service stated ominously, “Most of the area will be uninhabitable for weeks…perhaps longer.”
The city of New Orleans (population around 500,000 at the time) was especially vulnerable to hurricanes. Much of New Orleans is below sea-level. The Army Corps of Engineers built a system of seawalls & levees to prevent the city from flooding. Some of these levees were quite sturdy but tragically others were not.
Katrina brought a monstrous storm surge of up to 27 feet. Engineers knew that such a scenario would inevitably cause flooding by temporarily exceeding the height of the levee system. What they didn’t anticipate was that the surge would breech some levees completely, resulting in prolonged & devastating flooding.
More than 80% of the city of New Orleans suffered significant flooding which lasted for weeks. Parts of the city were under so much water that people desperately climbed onto roof tops. The Coast Guard heroically managed to rescue thousands. But despite their efforts, more than 1,800 people lost their lives. The storm caused a stupendous $125 billion in damages.
One of the most frequent claims we hear today is that global warming is causing more frequent and intense hurricanes. This claim seems quite plausible. Most everybody knows that hurricanes are fueled by warm waters. If global warming is causing an increase in water temperature, it makes sense that this phenomenon would fuel more frequent & more dangerous storms. But is that really true?
In 2014, a group of federal scientists (called the US Global Change Research Program, or USGCRP) published an influential report entitled National Assessment of Global Climate Change Impacts on the United States. This report claimed that there was a strong upward trend in hurricane activity in the North Atlantic Ocean. Their conclusion was based upon a metric called the “power dissipation index,” which measures the cumulative strength of all hurricanes based on maximum wind speed and duration. Strangely, the authors of the report limited the time frame of their study from 1970 to 2009.
Yet more data was readily available. Dr. Ryan Maue calculated the power dissipation index for North Atlantic hurricanes going back to 1920 and including the most recent data through 2013. Dr. Maue’s data gives us a much better understanding of overall hurricane activity in the North Atlantic.
The red portion of the graph is the limited data included in the 2014 National Assessment report. This cherry-picked data falsely suggests increasing North Atlantic hurricane activity. Thankfully, the full data shows no discernable trend at all.
You can see why the authors excluded the most recent data: the four North Atlantic hurricane seasons from 2010 through 2013 had relatively lower hurricane activity. Anyone paying attention to the news knows that the number and strength of North Atlantic hurricanes varies considerably from year to year. But over the last century, overall North Atlantic hurricane activity shows no signs of significant change.
For those of us living in the United States, North Atlantic hurricanes understandably get most of the attention. They’re the hurricanes which threaten the big cities along the East Coast and the Gulf of Mexico. But North Atlantic hurricanes account for only 15% of hurricane activity globally.
What about world-wide hurricane activity? Scientists have not always been able to track hurricanes around the world. Some storms never make landfall. They remain out at sea, sometimes far from shipping lanes or other human contact.
The advent of weather satellites in the last 40+ years has allowed scientists to comprehensively track storms. Dr. Ryan Maue has intensively studied global hurricane activity. His data (below) plots the total number of hurricanes as well as the number of major hurricanes – those storms classified as Category 3 or greater. Of course, the number of storms varies from year to year. But the data of storm frequency has been remarkably stable. The frequency of global hurricanes has not changed.
Of course, not every strong storm becomes a hurricane. We’ve noted earlier that a storm is not classified as a hurricane unless it produces sustained winds exceeding 74 mph. Storms with sustained winds between 39-74 mph are classified as “tropical storms.” The graph below shows the total number of tropical storms worldwide dating back to 1970. (The graph also includes hurricanes data from above.) Again, the numbers are very clear. The frequency of tropical storms has shown no significant change over the last 50 years.
However, the frequency of hurricanes is not the only way to measure of hurricane activity. The intensity of hurricanes can also be assessed using a metric called “accumulated cyclone energy” (Note: a cyclone is another name for a hurricane.) Like the power dissipation index, the accumulated cyclone energy is calculated based upon maximum wind velocity and duration.
Below is a graph of accumulated cyclone energy over the last 50+ years. Again, there is some variability over time. But the overall data shows no trend at all. In fact, from 2007 until 2015, there was a period of very low hurricane intensity even while our media and politicians were telling us that climate Armageddon was bearing down upon us.
You don’t need to be a scientist to reasonably interpret this data. Considering the hysterical climate alarmism that dominates much of our media and political discourse, many people might be shocked to learn that the frequency & intensity of hurricanes shows absolutely no upward trend over the last 40+ years.
Yet many politicians have repeatedly proclaimed that global warming is responsible for the powerful storms ravaging our coastlines. They attack and denigrate those who disagree with their viewpoint. It’s really quite astonishing how successful climate alarmists have been in deceiving so many people.
Despite their failure to predict the arrival of climate Armageddon over the last 40 years, climate alarmists seem undeterred. They continue to predict massive “superstorms” in the future which will devastate our coastlines and inundate our cities. It seems that for climate alarmists, disaster is always lurking right around the corner but never actually arrives.
Now some scientists do think that future warming might cause slightly stronger hurricanes. Such predications should be taken with a huge grain of salt. (Remember all those climate models which consistently predicted far more warming that we have observed?) However, let’s give them the benefit of the doubt and say that hurricanes really do become stronger. But would this be the end of the world? Hardly.
Chris Landsea holds a Ph.D. in Atmospheric Science from Colorado State University. He’s a widely respected meteorologist at the National Hurricane Center. Dr. Landsea’s studies indicate that future warming may result in hurricanes with 1% greater intensity than before. In other words, hurricanes would have wind speeds only 1-2 mph greater than they would have otherwise. A future hurricane might have maximum sustained winds of 162 mph, rather than 160 mph. A major storm like this would potentially inflict serious damage and result in loss of life. But the additional intensity would be negligible.
Attempting to cut fossil fuel use is the absolutely worst way to help people threatened by hurricanes. Many climate alarmists advocate spending trillions of dollars on expensive, unreliable wind & solar energy, despite the fact that hurricane activity has shown no change.
The best hurricane strategy is economic growth. Prosperous nations enjoy advance warning systems, durable buildings and infrastructure, strong sea walls and robust disaster response efforts. The devastation of Hurricane Katrina was so shocking because it was the exception to the rule. Americans don’t have to worry about such storms in the same way as people in the developing world.
Hurricanes striking developing nations can be utterly catastrophic, killing many thousands and causing economic devastation which lingers for decades. Economic growth is the best protection from hurricanes. That means developing countries should use more fossil fuels to build up their society just as we have. The real threat comes from climate alarmists who would waste trillions of dollars while denying people in the developing world the same blessings which we enjoy.
Here are some take home points: (1) The earth’s climate has been gently warming since the end of the Little Ice Age more than 300 years ago. (2) Human industry has made a small contribution to rising levels of CO2 in our atmosphere, especially since the end of World War II in 1945. (3) CO2 is a greenhouse gas which causes a slight slight warming effect. (4) The same natural forces warming the planet since 1700 are still at work today. Only a small amount of our present warming is attributable to human CO2. (5) The minor warming we’ve have experienced has been overwhelmingly positive. (6) Over the last 50 years, there’s been no significant change in global hurricane activity.
Those who hysterically claim we’re facing a climate crisis are producing a tempest in a teapot. Hopefully their minds can be changed. But if not, it’s vital that we avoid foolish policy proposals intended to end fossil fuel use. These misguided policies are the real storm which threatens the well being of humanity.
