Severe weather is not a new phenomenon. The U.S. has a long history of dealing with extreme weather events such as hurricanes, tornados, and floods. However, as our climate changes, our tropical system changes with it, intensifying the impacts of hurricanes and other severe weather events. The National Aeronautics and Space Administration (NASA) states there has been an increase in the proportion of hurricanes which reach Category 4 or 5 and an increase in rapidly intensifying hurricanes since the 1980s.
As our tropical systems are impacted by climate change, businesses and organizations need to change their emergency response plans accordingly. Changing weather risk profiles might make tried-and-true mitigation actions less effective than they once were, force businesses to begin preparations earlier than they have in the past, and spawn even the most unlikely and improbable weather events.
The Impacts of Climate Change on Tropical Systems
So, what are the main impacts of climate change on tropical systems? We see five major changes.
Higher winds. Meteorologists see an increase in the intensity of wind speeds. Most of us are familiar with the Saffir-Simpson scale, which gives hurricanes a 1 to 5 rating based on their sustained wind speeds. Over the last decade, we have seen more and more storms which reach Category 3 or higher (wind speeds of greater than 111 mph).
More rain. When Hurricane Harvey made landfall in 2017, it created a historic flooding event, with peak accumulations of more than 60 inches of rain. Although Hurricane Harvey was a rare event, 2018’s Hurricane Florence and 2019’s Tropical Storm Imelda both dropped as much as 30 to 50 inches of rain. With rising temperatures, tropical systems contain more rain than before, as warmer air can hold more moisture. For every degree of Celsius, there’s a possibility to contain 8% more moisture inside the same air. As a result, when hurricanes make landfall, they drop rain in larger amounts than we’ve seen before.
Slower storms. In addition to higher winds and more rain, climate scientists have observed storms have decreased their “translation speed,” or forward motion, by 10%. Slow-moving storms settle over an area for a longer period, increasing hurricane rainfall rates.
Late track intensification. Late track or rapid intensification is when a storm’s wind speeds increase by at least 35 mph in a 24-hour period, late in the path and close to landfall. For example, 2021’s Hurricane Ida became a major hurricane very late in its evolution, transforming from a tropical storm to a hurricane in just two days. As a result, one might have literally gone to sleep when it was a Category 1 or 2 storm and woke up to a Category 3 or 4. Additionally, there are more “pop-up” storms, forming much closer to landfall and reducing threat response times.
Storm fatigue. There is an increase in short-lived, weak, and named storms, typically lasting less than 48 hours. For example, during the 2021 Atlantic Hurricane Season, there were 10 short-lived storms. Although these storms never reached hurricane strength levels, they still needed to be treated seriously and responded to appropriately, creating more action events for businesses and organizations to handle.
Five Keys to Tropical Weather Risk Mitigation
The weather is its own master and cannot be stopped. So, what can be done? There are five critical keys to having a good risk mitigation strategy for severe weather events.
First, quantify the impacts of specific weather risks. Second, review proven mitigation actions to develop an understanding of what has worked in the past. Third, already-in-place mechanisms are necessary for timely threat identification. Fourth, adequate response times are necessary to handle threats in due time. Finally, execute mitigation actions.
Interestingly, these five keys to tropical weather risk mitigation are all put under stress by the impacts of climate change on tropical weather. Even if they do so in different ways, they all nonetheless feel the impact.
- Quantifying impacts: Understanding the impacts of specific weather risks is critical for businesses and organizations and a prerequisite to deciding what actions should be taken to avoid the impact. However, quantifying these impacts becomes more challenging as the climate changes. For example, factors like sea-level rise can affect the flood and storm-surge risk profiles for locations and evacuation routes. Where the storm will go or how easy it is for water to run off from flooding conditions can be impacted by something as simple as a few inches of changes in the sea level due to climate change. It becomes increasingly important to understand people’s impacts can change over time.
- Proven mitigation actions: Several mitigation actions have been tried and true for decades and used by organizations regardless of facility type or personnel. However, as risk profiles change, historically proven mitigation actions may no longer be adequate. For example, someone may be located at a site with a moderate risk of flooding. In that case, sea-level changes may make their previous mitigation actions (temporary water protection deployments or moving to higher grounds) inadequate. What’s worked in the past may continue to work but is no longer as effective.
- Timely threat identification: In many cases, the decisions made and actions executed are impacted by how much time it takes to do them. The sooner a threat is identified, the better equipped people are to mitigate it. With more volatility and a rising number of “pop-up” storms, warning times reduce. It becomes more difficult to identify threats in due time.
- Adequate response time: Climate change also puts stress on emergency response times. With storms forming closer to landfall, there’s often less time to identify and respond to threats. If one is unable to identify threats quickly enough, it becomes impossible to achieve adequate response times.
- Execution of mitigation actions: With less time available to identify and respond to threats, the risk of executing mitigation actions too late increases. To stay prepared, actions must be executed earlier than previously done and on events which are not yet fully realized as threats.
How to Adapt to a Changing Climate
The climate is changing, and how businesses and organizations respond to its effects on tropical weather systems should change accordingly. Businesses should consider implementing the following recommendations to stay prepared for a new environment with more severe and sudden tropical weather:
Identify what has changed for assets and operations. Understanding the changes caused by climate change is the first step to knowing what one might need to do differently or think about differently when moving forward. For example, if the level of storm surge required to produce flooding has changed, facilities close to the coast might be more likely to flood than they have in the past.
Evaluate response plans against recent real events. There’s value in testing one’s emergency plans. Go through an actual drill or exercise with a simulated storm to test response actions and the decision-making capabilities of personnel under stressful conditions. Because of the increased risk of storms with greater intensity, it becomes essential to not simply test them against the norm but also against extreme, outlier events.
Imagine the “impossible.” I lived in Houston when Hurricane Harvey made landfall, and I never expected 50-60 inches of rainfall totals. Was it possible? Sure. Did I ever think it was going to happen? Not at all. Making sure emergency response plans and mitigation actions are prepared for the improbable becomes ever more critical. Being ready for the “impossible” makes the possible seem like a piece of cake.
Think all the way through recovery. We often see hurricane response plans are well-tuned to what one should do before and during a storm. However, they are rarely as strong as they need to be in terms of thinking through what the recovery phase would be. During Hurricane Harvey, one refinery felt the effects of not having a well-thought-out recovery plan. The refinery knew how to handle the preparations ahead of major landfalling and the events unfolding during the landfall – and they did have a recovery plan in place. However, as their recovery plan was designed for normal storms, their recovery team could not relieve their ride-out team because of flooding rains. Having packed rations for only two to three days, the refinery had to send prescription medications and other supplies to the ride-out team via helicopter when they were stuck on-site for up to seven days. Consider not just what’s coming and what’s happening, but what one will do after it happens – even for improbable, outlier events.
Consider more than just hurricanes. The impact of climate change includes more than just hurricanes. For example, we’ve seen tornado outbreaks in mid-winter further north in the Ohio valley than in past years. Don’t assume past weather patterns are the ones to be seen in the future. What happens if tornado outbreaks occur during the summer or winter? With a changing climate, being vigilant and alert becomes critical.
