September 2017 record-setting month for hurricanes


15049990995_b4bb48f85b_o
A satellite image of Hurricane Maria. (Sturart Rankin/flickr)
Jenna Ladd | October 4, 2017

September 2017 was a record-setting calendar month for hurricane activity in the Atlantic ocean.

The beginning of September brought Hurricane Harvey, a category four storm which caused unprecedented damage to the U.S.’s fourth largest city, Houston. Five additional hurricanes left paths destruction across the Caribbean and Florida later in September, with Irma and Maria both reaching category five status.

It is common for September to be the most active month for hurricanes because low pressure systems often move across the Atlantic from Africa and meet the tropical waters of the Caribbean at this time, but September 2017 was a cut above the rest. According to Phil Klotzbach of Colorado State University, September 2017 featured 18 “major hurricane days,” beating 1961’s record of 17.25 “major hurricane days.” Last month, the overall intensity and duration of storms, known as “accumulated cyclone energy,” was 175 units, significantly higher than September 2014’s record of 155 units.

While climate change has not been found to cause hurricanes, there is evidence to say that rising sea temperatures cause hurricanes to be more intense.

On The Radio – Storms like Harvey more likely due to changing climate


36015109024_f735263607_o
Texas National Guard members rescue residents in a heavily flooded area of Houston. (Texas Military Department/flickr)
Jenna Ladd| September 11, 2017

This week’s On The Radio segment discusses how climate change is making storms like Harvey more likely.

Transcript: Over 51 inches of rain fell in the Houston area last month during Hurricane Harvey, setting a record for the continental U.S., and scientists say a changing climate added to the deluge.

This is the Iowa Environmental Focus.

The Clausius-Clapeyron equation, a law of thermodynamics, says that the warmer a body of air is, the more moisture it can hold. Sea surface temperatures near where Harvey picked up its strength were about 1 degree Celsius higher than average, making the air above it warmer too. In this case, the atmosphere surrounding Hurricane Harvey was able to hold roughly three to five percent more moisture than usual.

In addition, sea levels have risen by about six inches in the last few decades due to global warming. Even minimal sea level rise can lead to a large increase in damages to structures on land during a flood.

While climate change did not cause Hurricane Harvey directly, scientists say it will likely make category four storms like it more frequent in the future.

For more information, visit iowa-environmental-focus-dot-org.

From the UI Center for Global and Regional Environmental Research, I’m Betsy Stone.

Lessons for Iowans in the wake of Harvey


Screen Shot 2017-09-06 at 6.45.00 PM
A map from the National Hurricane Center illustrates predicted landfall for Hurricane Irma, a category 5 storm, over the weekend. (National Hurricane Center)
Jenna Ladd| September 7, 2017

As some of the floodwater finally recedes from the Houston area following Hurricane Harvey,  Hurricane Irma, a category five storm, threatens to devastate the Florida Keys this weekend.

Climate change increased the amount of rainfall that fell on Houston during the recent storm, according to a statement from Clare Nullis Kapp, media officer for the World Meteorological Organization. Karen Tigges, a Des Moines resident and operations analyst at Wells Fargo, said in a recent Des Moines Register Letter to the Editor that Harvey has something to teach the people of Iowa. The letter reads:

“Houston: A tragic example of a city caught at the mercy of worsening storms and increased rainfall. Flooding is nothing new to Houston, but it appears that this time they are really paying the price for unwise growth.

Unfortunately, flooding is not unfamiliar to the city of Des Moines either. We are growing in the metro as well. We must take the warnings of storm events seriously. It’s said that the lack of zoning ordinances in Houston led to the loss of wetlands and grasslands that could have absorbed at least some of the onslaught of water. How does that compare with planning for growth here in the metro area? Is the growth of our urban areas leading to higher risks of flooding due to more impermeable surfaces in the form of more paved roads and rooftops?

As the city prepares for a future that will likely include more intense rainfall events, thanks to a warmer, more humid climate, we citizens need to take an active role in seeing that effective planning and policies are put in place to make Des Moines ready to face this unpleasant reality.

We can do that by weighing in on the city’s new planning and zoning code. We also need to do that by electing and supporting leaders that will be proactive in setting the course of the metro area on a path of resilience and preparedness for what storms of the future may bring.”

— Karen Tigges, Des Moines

Climate change to make storms like Harvey more frequent, intense


36709598191_d9004d75c3_o.jpg
A Texas National Guard member rescues a Houston resident during Hurricane Harvey. (The National Guard/flickr)
Jenna Ladd| August 30, 2017

More than fourteen million olympic-sized swimming pools could be filled with the amount of rain that has fallen in Houston as a result of Hurricane Harvey, and scientists say that climate change added to the deluge.

To begin, sea surface temperatures near where Harvey picked up its strength were about 1 degree Celsius higher than average. The Clausius-Clapeyron equation, a law of thermodynamics, says that the warmer a body of air is, the more moisture it can hold. In this case, the atmosphere surrounding Hurricane Harvey was able to hold roughly three to five percent more moisture than usual.

“The water in the Gulf of Mexico is the heat reservoir to support these hurricanes,” said Ben Kirtman, an atmospheric scientist at the University of Miami, in a report from NPR. Kirtman added, “For a small change in temperature, you get a huge amount of evaporation.”

In the last three decades, sea levels have risen worldwide by about six inches thanks to a warming climate and, in part, to human activities like offshore oil drilling. Higher sea levels make inland floods more devastating.

Climate Central scientist Ben Strauss said, “Every storm surge today reaches higher because it starts from a higher level, because sea level is higher. A small amount of sea-level rise can lead to an unexpectedly large increase in damages to most kinds of structures.”

Scientists are careful to point out that climate change did not directly cause Harvey, but is likely to produce storms like it more often. A recent report from the National Academy of Sciences, Engineering and Medicine revealed that category 4 hurricanes like Harvey will occur more frequently in the future due to a warming climate.

So far, fourteen casualties have been identified as the storm continues to devastate the area.

Natural disasters cost $175 billion in 2016, highest since 2012


30988304984_fdd35ded4d_o
St. Antoine hospital in Jérémie, Haiti was among the structures damaged when Hurricane Matthew ravaged the country earlier this year. (CDC Global/flickr)
Jenna Ladd | January 6, 2017

Shortly after the New Year, German insurance giant Munich Re announced that natural disaster damages were higher in 2016 than they have been since 2012.

Insurance losses totaled $175 billion over the last twelve months, which is two-thirds more than in 2015. The company counted 750 natural disasters internationally, which includes “earthquakes, storms, floods, droughts and heatwaves.” The 6.9 magnitude Earthquake that shook southern Japan was the world’s most costly natural disaster this year, claiming $31 billion in damages.

North America was plagued with the most natural disasters it has seen since the 1980’s, it experienced a total of “160 loss events in 2016.” Spring heat waves in Canada led to wildfires in Alberta, costing the region $4 billion, while August floods in the southern United States racked up $10 billion in losses.

Flood events made up 34 percent of this year’s total losses. Comparatively, these events accounted for 21 percent of total losses over the last ten years. Flash floods in Germany and France cost the region almost $6 billion this year. Peter Hoppe, head of Munich Re’s Geo Risks Research Unit, said these increases are related to “unchecked climate change.”

Hoppe said, “Of course, individual events themselves can never be attributed directly to climate change. But there are now many indications that certain events — such as persistent weather systems or storms bringing torrential rains – are more likely to occur in certain regions as a result of climate change.”

Indeed, a recently published report from the World Meteorological Organization outlines the relationship between human-induced climate change and the increasing frequency and intensity of natural disasters. Among other examples, the authors point out that the 2013 Australian heat wave was made five times more likely because of human-induced warming.

The report said, “Extreme events are always a result of natural variability and human-induced climate change, which cannot be entirely disentangled.”