I enjoyed the visit at the Department of Civil and Environmental Engineering at Princeton University. I have had great discussions with Professor Lin and her Hurricane Hazards and Risk Analysis Research Group.
I am honored to be invited to give a seminar talk, entitled "Understanding Human Judgement on Environmental Risks and Hazards in a Geographic Context," at the Department of Civil and Environmental Engineering at Princeton University on June 21.
The abstract of the talk is as follows:
"The coupling effects of changing climate and rising concentration of population and assets in the coastal regions have increased the threat of potential damages. There is an urgent need for coastal communities to prepare well for future hazards through mitigation and adaptation measures. A growing number of empirical studies have found that peoples’ motivation of voluntary risk mitigation and adaptation is low unless actual risk can be perceived. Risk perception is thus the precondition for adaptive behavior. It is of both intellectual and practical interests to study what affects individuals’/communities’ risk perceptions. In this talk, I will present four of my previous studies. The first three studies are focused on the individual level and the fourth on the aggregate level. I will start with understanding how local weather and climate affect American public risk perceptions of climate change. I will then discuss how the spatial context represented by past flooding events and estimated flooding risks influence costal residents’ voluntary flood insurance purchase decisions and their support for flood adaptation policies. As many policies are designed and implemented at an aggregate level (i.e., state, county, city), it is necessary to examine aggregate-level risk perceptions. In the fourth study, I will focus on how the contextual hurricane risks in conjunction with community resilience shape county-level perceptions of hurricane-related risks. I will end with a research agenda linking communities’ perception with contextual risks and community resilience. I contend that the cognitive dimension including both risk perceptions and perceived adaptive capacity is not represented in any of the existing community resilience indexes, and therefore needs to be measured, quantified, and incorporated into a more comprehensive index."
Hurricane Harvey dumped record-breaking rain in Houston in 2017. Now, a new study shows that this extreme amounts of rainfalls actually resulted from unprecedented ocean heat content. This study presents some evidence to support the link between global temperature rise with increasing hurricane intensity.
Our new paper on aggregate perceptions of hurricane risks has been published on the Annals of American Association of Geographers.
The obesity rate has been rising rapidly in America over the past two decades. Many factors have been identified as contributors to this ongoing public health crisis. The food industry plays a powerful role shaping public perceptions of food and eating behaviors, as this Vox article explains.
As a geographer, I am always concerned with the influence of our surrounding environment on what we perceive and how we behave. In this paper, my coauthors and I have considered the impacts of built and natural environments on physical inactivity and correspondingly obesity rate. We have made a couple of findings. First, higher street connectivity and walk scores are related to lower physical inactivity and obesity rates. In a more pedestrian-friendly environment with more streets and connections, people tend to be more physically active and less likely to be obese. Second, higher ratio of fast-food restaurants in a community is positively related to physical inactivity and obesity. Surprise, surprise, fast-food makes people become more obese, well, because in the fast-paced modernity, fast-food is literally fast and therefore convenient for people to grab and eat on the go.
Last but not least, the number of extreme weather events is also found to lead to physical inactivity and obesity. When extreme weather events occur, the environment outside the window all of a sudden becomes hostile. People are constrained inside, much less likely to get engaged in any exercises. So, these extreme weather events pose threats to not only public safety but also public health.
Natural disaster is never purely natural. The moment when a natural event such as a hurricane, tornado, or wildfire "meets" with a societal community on its path, the event has the potential to become a disaster from the perspective of human society. Hurricanes essentially serve as nature's venue to reallocate energy geographically from the tropical region to higher latitudes. But because some communities are built on the usual path of hurricanes, they are vulnerable to this type of natural events. Hurricane Maria has left the U.S. territory Puerto Rico in despair. Because of its geographic location, Hurricane Maria certainly will not be the last one to affect this region. To build better resilience, the first thing every community needs to do is raise its awareness of such interactions between nature and society.
After the wind diminished and water receded, coastal communities in Texas and Florida face a long way to recovery. Many of these affected communities need to not only repair or rebuild their homes but also restore their health since disasters of such scales can take a toll on one's health, both physical and mental.
Hurricane Matthew has left at least 1000 Haitian dead, tens of thousands homeless, and millions in dire need of assistance. In the U.S., it has led to 19 deaths, left millions without power, and caused massive floods in North Carolina.
We are reminded once again how powerful and destructive natural hazards can be. People in Haiti will face a long recovery. Billions of economic damages will be inflicted by Hurricane Matthew in southeastern U.S. The vivid memory of this hurricane may stay with many people who have witnessed its monstrous presence at first hand. This once-in-a-life experience may also determine many people's judgments on the changing pattern of hurricane strength.
My coauthors and I in our paper on perceptions of changing hurricane strength found that maximum wind speed from the last landfall is the most powerful predictor of an individual's perception of changes in hurricane strength among the characteristics associated with the last hurricane landfall. Coastal residents who experienced higher maximum wind speeds are more likely to think hurricanes are becoming stronger. It appears that maximum wind speed tends to leave the deepest impression in coastal residents' memories, which includes impressive surf along the beachfront, as well as swaying and felled trees, and flying debris. Winds can be very destructive. The Saffir-Simpson categorization of hurricanes is therefore based on wind speeds. However, the biggest threat to life and property is actually water, not wind. Storm surge is a bigger contributor to deaths compared to winds. Super Storm Sandy is a perfect example. It was identified as a Category 1 storm. However, its enormous size and high storm surge had incurred tremendous amounts of property damages in the densely populated east coast.
So, once again, there is a mismatch between perceived and actual risks.
Shao, W., Xian, S., Keim, B. D., Goidel, K., and Lin, N. 2016 “Understanding perceptions of changing hurricane strength along the U.S. Gulf Coast” International Journal of Climatology. DOI:10.1002/joc.4805
"Wind speed alone isn't the best way to measure a weird hurricane like Matthew," http://fivethirtyeight.com/features/wind-speed-alone-isnt-the-best-way-to-measure-a-weird-hurricane-like-matthew/
Hurricane Matthew is swirling across Florida, Georgia, and South Carolina. It has left hundreds of people dead in Haiti when passing through. People in Haiti will face a long recovery after the worst hurricane in 50 years. Hurricane Matthew has also left 300,000 people in Florida without power. It is poised to incur tremendous amount of damages. Every time when we experience extreme weather events of this magnitude, we feel impulsed to ask the 1-million-dollar question, "is climate change to blame?" We know for sure that hurricanes form over a large body of warm water. With the global temperature rising and oceans heating up, the intensity and frequency of hurricanes will theoretically increase. In reality, though, our observations have not been able to depict a clear picture of increasing trends of hurricane intensity and frequency.
Here is a Washington Post article on what we can and we can't say about climate change and Hurricane Matthew:
For more scientific inquiry, check out NOAA Geophysical Fluid Dynamics Laboratory's overview of current research results about global warming and hurricanes:
The southern Louisiana was absolutely devastated by an epic flood last week. Tens of thousands of people were displaced due to this historically unprecedented flooding event. 13 people died of this event, 40,000 homes were damaged, and 20 parishes were declared Federal Disaster Area. For many residents in these communities, this flood was even more destructive than Hurricane Katrina. Here, I post some pictures of the neighborhood I used to live in.
The street was full of trash in the aftermath.
Inside the house after the water receded
After the worst natural hazard since Super Storm Sandy, many coastal communities are facing a long recovery. When interviewed by NPR's On Point, my former doctoral advisor Dr. Barry Keim, Louisiana State Climatologist, was asked if this epic flood was related to climate change, Dr. Keim pointed out that it was difficult to determine an absolute link between climate change and a single event. His response highlights the key to understanding climate change. By definition, climate change refers to “a change in the state of the climate that can be identified by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer," according IPCC. Lay persons are more likely to be influenced by isolated extreme weather events when making judgments about climate change. More frequent extreme weather events, though, collectively form a pattern that can be attributed to climate change.
The economic damage from flooding in the coastal areas has dramatically increased over the past several decades. One effective way to mitigate excessive economic losses from flooding is to purchase flood insurance. In reality, only a minority of coastal residents however have taken this preventive measure. In order to understand the driving force behind individuals' decision to voluntarily purchase flood insurance, my coauthors and I examine how external influences and perceptions of flood-related risks together with socio-demographic factors affect this voluntary behavior in the U.S. Gulf Coast by using survey data merged with contextual data. This paper has been published on Water Research.
Our findings indicate that estimated flood risks conveyed through FEMA's flood maps, intensities and consequences of past storms and flooding events, as well as perceived flood-related risks significantly affect individuals’ voluntary flood insurance purchase behaviors. The finding about FEMA's flood maps has significant policy implication that FEMA’s flood maps have been effective in conveying local flood risks to coastal residents, and correspondingly influencing their decisions to voluntarily seek flood insurance. Flood maps therefore should be updated frequently to reflect timely and accurate flood risks.