The Rundown - What We Know
- August 25th - Hurricane Harvey makes landfall in southeastern Texas as a Category 4 storm with winds of 130 mph
- September 6th - Hurricane Irma, which reached a maximum wind speed of 185 mph, hits the eastern Caribbean as a Category 5 storm
- September 8th - Hurricane Jose remains stagnant in the southeast Caribbean as a Category 4 storm before moving towards central Mexico
- September 10th - Hurricane Irma makes landfall in the Florida Keys as a Category 4 storm
- September 18th - Hurricane Maria devastates the islands of Puerto Rico and Dominica as a Category 4 storm. Over 95% of Puerto Rican's are without power and experts are saying it could be months before power is restored to the island.
September is historically the most active month of the Atlantic hurricane season, leaving many to wonder how much more we can handle. As communities across the coastal United States and the Caribbean begin their rebuilding efforts, let us reflect on the 2017 hurricane season thus far and put these storms into historical perspective. For the first time on record, the continental U.S. had two Category 4 landfalls in the same year- Harvey and Irma. Hurricane Harvey brought unprecedented rainfall to southeast Texas - producing 51.88” of rain in Cedar Bayou, Texas - the most rain ever recorded in the continental U.S. because of a tropical storm.
As global temperatures continue to rise, climate change will remain at the forefront of urban planning, coastal management, and emergency preparedness discussions. Public policy frequently excludes climate science, impacting the effectiveness of proposed solutions. Faced with global climate change, what can citizens and government officials do to rethink emergency planning? The first step is to learn more about the science and work to understand what it is telling us.
The Scientific Evidence of Change
Dramatic atmospheric warming over the past century is the result of human activity and the burning of fossil fuels. While there are a number of different materials that are harmful to the planet when we burn fossil fuels, CO2 is likely the most famous. These materials, known as greenhouse gases, trap heat inside the atmosphere and work to keep the Earth warm enough to sustain life. However, too much greenhouse gas in the atmosphere will trap in more heat than we need, gradually warming Earth’s temperatures to a point that is unsustainable for a growing population. While scientists have proven that Earth has moved through relatively warm and cold periods throughout our history, the exponential rise in global temperatures since the beginning of the 21st century is a direct result of human activity and the release of greenhouse gas emissions into the atmosphere.
Climate scientists have been able to measure the direct impact of greenhouse gases on many of Earth’s processes, including ocean acidification and considerable melting of the world’s ice caps and alpine glaciers. Greenhouse gases have increased atmospheric temperatures, resulting in significant changes to atmospheric patterns and an increased frequency of severe weather events such as droughts and heavy rainfall.
But how does global warming specifically affect the intensity of tropical storms? As the temperature of the atmosphere increases so does the temperature of surface and ocean water. When you heat up water, you excite all of the atoms that make up each water molecule. Think about how a pot of water becomes excited as it begins to boil on the stove, the water has more energy as it heats up. This energy is what causes evaporation, and more evaporation means more water in the atmosphere. As temperatures continue to rise, we can expect to see more intense rainfall associated with storm events.
What Scientists Learned From Superstorm Sandy
Hurricane Sandy surprised New Englanders when it struck New York and New Jersey in October of 2012. Residents along the northeast coast assumed that tropical storms could not reach them and the lack of emergency preparedness in many coastal communities supported this assumption. Tropical storms rarely make landfall north of Florida because of prevailing winds in the middle of the northern hemisphere that push storms back out to sea once they reach 30 degrees latitude.
Like many tropical storms before, Sandy originated off the eastern coast of Africa and traveled across the Atlantic Ocean towards the Caribbean. For storms that survive this journey across the ocean, the majority make landfall in the Caribbean, Central America, or the Gulf of Mexico. Sometimes tropical storms have their sights set much farther north to New England and the eastern United States coastline. While along this northward path, strong winds and ocean currents usually divert these storms back to sea and leave behind a trail a heavy rainfall. Along with ocean currents and westerly winds between 30-60 degrees latitude, the Polar Jet Steam, a strong air current that moves eastward across North America and circles the Earth in the northern hemisphere, can influence the direction and path of these wayward storms.
Some climate scientists are pointing to an extremely warm Arctic summer to potentially explain this phenomenon. Sea ice levels reached record lows during the 2012 summer season, exposing more open water to incoming solar energy, ultimately adding more heat and moisture to the atmosphere. These changes helped alter weather patterns and could have influenced the atmospheric roadblock above Greenland, but this hypothesis is still undergoing research. This raises the question amongst scientists and emergency management officials, are these random events the new normal?
Where We Go From Here
Unfortunately, climate research is still too dense and difficult for many of us to understand. In order for science to find its way into public policy, scientists must strive to make their research accessible to everyone. This starts with developing science education and seeking better ways to communicate climate change to those outside the scientific community. The debate surrounding climate change is far from over. As the climate continues to change, there will be many more questions asked than questions answered. There is work to be done to make sure coastal management plans are holistic and include insight into climate change mitigation strategies. Thankfully there are solutions out there and innovation can come from anywhere and anyone. Moving forward, it will be of the utmost importance that public safety officials have access to new information and technologies.