A new paper published on Economics Letters claims that low rainfall can predict assassinations of Roman Emperors from 27 BC to 476 AD. The logic line is: low rainfall -> low food supplies -> more troop mutinies -> assassination of Roman Emperors. Being creative enough, one can find no shortage of interesting topics to study.
A new NBER working paper shows aggregate-level evidence that indicates cumulative exposure to heat can have detrimental impacts on learning. The authors suggest school air conditioning can help mitigate the adverse effects. Evidently, more studies need to be conducted in developing countries where air conditioning is not universally available.
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.
Extremely cold temperature can be utilized by politicians as counter evidence to climate change. Scientists, trained to be cautious, need to conduct rigorous studies to either confirm or fail to confirm any hypotheses. A new study shows that the deep freeze in the U.S. is not related to climate change.
It has long been speculated that the regional climate plays a role in shaping personalities. Recently, a group of researchers mainly from China and the U.S. have used large-scale data, multilevel analyses and machine learning analyses to test this hypothesis. Nature Human Behavior just published their study linking regional temperature with human personality. The authors have made some interesting but intuitive findings. Personalities related to socialization and stability such as agreeableness, conscientiousness, and emotional stability, and personal growth and plasticity such as extraversion and openness to experience are often associated with more clement temperature along with which individuals grew up. They further suggested that climate change may bring concomitant changes in human personality.
Once again, this finding resonates with the notion that we are products of our surrounding environment.
The U.S. Global Change Research Program just released a Climate Science Special Report. In this report, the increasing trend of global annually averaged air temperature over the past century has been reiterated. Like IPCC's most recent assessment report, this report also uses "extremely likely" when attributing the warming trend since the mid 20th century to human activities, "especially emissions of greenhouse gases." The continually rising global temperatures have brought about a wide range of impacts such as sea level rise, glacier melting, ocean acidification, more frequent extreme weather events - wild fires, hurricanes, heavy rainfall, heat waves, etc.
This report also states that "over the next few decades (2021 -2050), annual average temperatures are expected to rise by about 2.5°F for the U.S., relative to the recent past (average from 1976-2015), under all plausible future climate scenarios." To many people, 2.5°F does not seem to be an impressive number to cause substantial concern. But if we put this number in the context of a normal distribution, we have every reason to worry a great deal about the future of the global climate and its implications for human civilization. As Joseph Romm explains in this Podcast episode, if we move the "bell curve" (normal distribution of temperatures) as a whole towards the upper end, as the current trend suggests, not only do we see the mean temperature rise but also witness the increasing frequency of high temperatures currently deemed to be abnormal. In other words, a new norm will need to be defined with more "extremes" becoming more frequent and normal.
Thanks to a relatively steady climate, the humanity has managed to achieve a high level of civilization over the past 10000 years. Today, the need to feed an ever growing world population and the resulting intensifying industrialization are disrupting the global climate system on which our survivals are largely reliant upon. In the entire history of our existence, the human species has displayed magnificent adaptive capacity to the environment. But many would argue that there is a limitation to adaptation. It takes time for an individual, a community, or a society to learn and adopt appropriate measures to adapt to a new environment. When the extreme loses extremity by becoming the new "norm" every few years, one cannot help but wonder how fast we need to learn and make necessary changes to keep up with nature. We don't need to look far to find ample evidence in history that rapid climate change can bring an end to a sophisticated social and political system. A prime example would be the collapse of Roman Empire. When the climate changed abruptly, even the mighty Roman Empire could not evade the fate of collapse.
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.
While coastal residents in Texas and Florida are still lamenting the loss from extreme weather events (Harvey and Irma), patent applicants may wish their applications would be evaluated on a hotter than usual day with higher cloud coverage, because this paper claims hot weather is associated with lower final rejection rates. Obviously, a lot of work needs to be done to validate this claim.
As different as weather is from climate, these two concepts are often used interchangeably in everyday language. At the end of the day, they are both descriptions of atmospheric behaviors, aren't they? According to NASA, the key difference between weather and climate lies in the different time scales on which they operate. Weather refers to the atmospheric condition over a short window period of time (hour, day, week), whereas climate is the accumulation of weather over an extended period of time. Geographic scale can add another layer of distinction to this. Weather usually covers a relatively limited area while climate over a large region.
One of the fundamental challenges facing climate scientists and science communicators is how to effectively communicate long term changes in the atmosphere (climate change) to the public who may confuse climate with weather. As rational as we may wish to be, our minds are actually prone to many mental heuristics and biases (Tversky and Kahneman 1974). For instance, when being asked about long term changes in hurricane strength - "do you think hurricanes have become stronger?"- coastal residents are more likely to take into account their observations of characteristics of the most recent hurricane landfall such as maximum wind speed and storm surge, rather than the actual trend of hurricane strength over the recent past (Shao et al. 2016). This is classic illustration of availability bias, referring to the mental tendency to turn to the most accessible and retrievable events (Tversky and Kahneman 1974).
The seemingly clear conceptual delineation between weather and climate can be blurred if entering extreme weather events. Scientists are now taking on a big task to disentangle specific extreme weather events and climate change. Whether or not Louisiana's Epic Flood (2016) is a direct product of climate change may be still subject to debate. Scientists nevertheless can say that climate change is certainly driving up the frequency of extreme weather events, essentially making 1000-year (the chance for an event to occur in any given year is 1 in 1000) or 500-year events become 50-year or 10-year events. When people start to see the overall pattern that extreme weather events have become the new norm across the globe, hopefully it will make the case of climate change more convincing and scientists' communication less challenging.
Shao, W., Xian, S., Keim, B. D., Goidel, K., & Lin, N. (2016). Understanding perceptions of changing hurricane strength along the US Gulf coast. International Journal of Climatology.
Tversky A, Kahneman D. 1974. Judgment under uncertainty: heuristics and biases. Science 185(4157): 1124–1131.