Risk perceptions have been intensively studied because they are believed to induce behavior change, which would have consequences in the world. Now, a group of researchers from multiple disciplines have taken this idea one step further by linking human behavior model with climate model. Their study has just been published on Nature Climate Change. It is exciting to see this kind of integrative approach in the climate research field. The complexity of climate change really requires concerted efforts of scientists from a wide range of disciplines.
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.
While some federal agencies such as EPA and DOE are under increasing political scrutiny and pressure on their climate research and communication efforts, the National Academies of Sciences, Engineering, and Medicine as an independent entity is doubling down the effort to engage the public and decision makers on the scientific consensus of climate research. The Academies just launched a Climate Communications Initiative.
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.
After Harvey dumped over 40 inches of rain in Houston over a few days, the city must come to the realization that it cannot continue to be built and relentlessly expanded by ignoring science. Now, it is time for the city to rethink about its development plan and hazard mitigation policies.
The prominent hurricane scientist Kerry Emanuel wrote a perspective piece on Washington Post. He pointed out that "natural disasters" such as Harvey and Irma are not that natural after all. Too much government interference in the insurance market has distorted insurance premiums so much by providing heavy subsidies that they do not reflect the real risks faced by coastal property owners, which has unintentionally encouraged intense development in coastal areas. In the meantime, too little regulation on carbon emission, the root cause of anthropogenic climate change, will only make hurricanes stronger.
Well, whether it's "too much interference" or "too little regulation," they both reflect a fundamental aspect of human psychology. We are more sensitive to immediate losses at present than some potential gains in the future.
In 2017, coastal residents in the U.S. have witnessed something extreme. Two Category 4 hurricanes made landfalls in the continental U.S. in the same year, first year on record. The old debate on hurricanes and climate change has been reignited. The relationship between hurricanes and climate change is very complicated, more so than many think. I am going to post part of a literature review report I wrote in graduate school (2009) here:
"One possible manifestation or implication of climate change is the increasing hurricane activity in the past 35 years. Especially, an increase in the number and intensity of major hurricanes in Nothern Atlantic basin has been witnessed since 1995 (Goldenberg et al. 2001; Pielke et al. 2005; Webster et al. 2005). Since the limited instrumental record makes extensive analyses of hurricane activities globally impossible, the North Atlantic region with relatively reliable instruments which can be dated back to early 20th century has become the center of study on the relationship between climate change and hurricanes (Henderson-Sellers et al. 1998). Similar to the on-going discussion “human induction or nature?” in the broad realm of climate change, there is a debate on climate change and hurricanes. One side believes the upward trend of Atlantic hurricane activity is correlated with the increase of Sea Surface Temperature (SST) induced possibly by increasing green house gas forcing (Emanuel 2005; Webster et al. 2005; Elsner 2006; Emanuel 2007; Holland and Webster 2007). In comparison, the other side attributes this to natural variability. They believe the increased Atlantic hurricane activity in the recent years are just the reflection of the multidecadal-scale variability and it is premature to conclude that the increased activity is the result of green house warming (Goldenberg et al. 2001; Piekle et al. 2005; Landsea et al. 2006).
A tropical cyclone (TC) is the generic term for a nonfrontal synoptic-scale low pressure system originating over tropical and subtropical waters with organized convection and definite cyclonic surface wind circulation (Henderson-Sellers et al. 1998). When the surface winds reach 33 m/s, a hurricane (the North Atlantic Ocean and the northeast Pacific Ocean) is formed (Henderson-Sellers et al. 1998).
Emanuel (2005 a.) applied a hurricane destruction index- power dissipation index (PDI), which is a combined measure of Atlantic hurricanes frequency, intensity and duration to his statistical analysis and found there was a significantly strong relationship between PDI and SST. Just after Emanuel’s article was published on Nature, Pielke and Landsea cast their doubts on Emanuel’s method. Pielke (2005) argued that the data used by Emanuel were not normalized and the effect of societal changes was another factor on the hurricane destruction. Landsea (2005) pointed out the flaws existing in Emanuel’s graphs in which the end-points remained unaltered in smoothing, bias-removal scheme used to alter the data for the Atlantic for 1949-69. In response, Emanuel (2005 b.) insisted on his conclusion about the trends in tropical-cyclone power dissipation since this trend was large and universal, though he gave credits to Piekle for taking societal changes into account and accepted the correction of dropping the end-points in smoothing while he also emphasized that “this error has comparatively little effect on the high correlation between PDI and SST.”(Emanuel 2005 b. E13)
Webster et al. (2005) carefully examined the time series of SST by ocean basin, number of intense hurricanes and percentage of intense hurricanes and came to the conclusion that there is a 30-year trend toward more frequent and intense hurricanes based on the global data. On the other hand, Landsea et al. (2006) cast their doubt on the reliability of current global tropical cyclone databases to ascertain long-term trends in tropical cyclone intensity. They argued that constrained by the imperfect technique of monitoring and estimating the hurricane intensity, “the pre-1990 data for all basins are replete with large uncertainty, gaps, and biases.” (Landsea et al. 2006, 453) Holland & Webster (2007) did a more detailed study on the long-period variations in tropical cyclones and hurricane frequency in the North Atlantic Ocean and concluded the upward trend of the number of tropical cyclones concur with the increasing trend of SST. To further complicate matters, Holland & Webster (2007) also found the contradiction of conclusions made by the other side. They pointed out that on one hand these papers (Landsea et al. 1999; Goldenberg et al. 2006; Owens & Landsea 2003; Landsea et al. 2006) “describe the data as being of high quality sufficient to determine natural variability in hurricane characteristics but, on the other hand, of insufficient quality to determine trends that are demonstrably of similar magnitude.” (Holland & Webster 2007, 2712)
As one more piece of evidence to support the climate change effect on Atlantic hurricane hypothesis, Elsner (2006) applied Granger Causality Tests, which is used to determine whether one time series is useful in predicting another by comparing two sets of models involving lagged values of the predictor variable, and concluded that global temperature causes Atlantic SST and Atlantic SST causes the PDI in the Granger sense. Meanwhile, the projection model (Knutson & Tuleya 2004), lent little evidence to the notion that green house warming leads to the upward trend of tropical storm numbers, hurricane numbers despite the significant statistical correlation between SST and Atlantic hurricane activity in recent decades. However, they suggested the intensity of the hurricanes was projected to increase by a few percent (Knutson 2008).
In the process of literature review, I have noticed one interesting thing. The authors of one paper (Henderson-Sellers et al. 1998) published in 1998 included the important representatives of the current two major schools. Emanuel, Holland, Webster of “climate change” and Gray, Landsea of “natural variability” contributed to the same paper. In the introduction section, these authors seem to all agree that “different definitions, techniques, and observational approaches may produce errors and biases in these datasets that could have implications for the study of the natural variation of tropical cyclone activist and the detection of possible historical trends.” (Henderson-Sellers et al. 1998, 20) This seems to imply that these scholars had realized that their clashing conclusions and views on the same issue were inevitable before they debated each other years later.
The side of natural variability also provides a societal perspective to this connection of human-caused climate change to hurricane impacts. Piekle et al. (2005) put the emphasis on the hurricane damages to the society and stated that “the future damages to society of its projected changes in the behavior of hurricanes are dwarfed by the influence of its own projection of growing wealth and population.” (1574) In some sense, they should be given credit for their attempts to include the society vulnerability into this discussion. They stressed the importance of adaptation to hurricanes."
In addition to the physical complexity of climate change and hurricane activities, let's not forget the basic definition of climate. Climate is the accumulation of weather over an extended period of time. If we continue to witness the overall pattern of increasing hurricane activities, we may be in a better position to draw a causal line between hurricanes and climate change. For this year's hurricanes alone, I am afraid we cannot directly connect them to climate change with substantial certainty.
Elsner, J. B., 2006. Evidence in support of the climate change-Atlantic hurricane hypothesis. Geophysical Res. Letters, Vol. 332, L16705
Emanuel, K. A. 2005 a. Increasing destructiveness of tropical cyclones over the past 30 years, Nature, 436, 686-688.
Emanuel, K. A. 2005 b. Emanuel replies, Nature, Brief Communications Arising 438 E13
Goldenberg, S.B., C.W. Landsea, A. M. Mestas-Nunez, and W. M. Gray, 2001: The recent increase in Atlantic hurricane activity: Causes and implications. Science, 293, 474-479.
Henderson-Sellers, A. et al. 1998. Tropical cyclones and global climate change: a post-IPCC assessment. Bull. Am. Meteor. Soc. 79, 19-38.
Holland, G. J., and P. J. Webster, 2007. Heightened tropical cyclone activity in the North Atlantic: natural variability or climate trend? Phil. Trans. R. Soc. A 2007 365, 2695-2716.
Knutson, T. R., and R. E. Tuleya, 2004. Impact of CO2-induced warming on simulated hurricane intensity and precipitation: Sensitivity to the choice of climate model and convective parameterization, J. Clim., 17, 3477-3495.
Knutson, T. R., J. J. Sirutis, S. T. Garner, G. A. Vecchi and I. M. Held, 2008 Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions. Nature Geoscience doi: 10.1038/ngeo202
Landsea, C. W. 2005. Hurricanes and global warming. Nature, Brief Communications Arising 438 E11-E12.
Landsea, C. W., Harper, B. A., Horau, K. and Knaff, J. A. 2006 Can we detect trends in extreme tropical cyclones? Science, Perspect. 313, 452-454.
Pielke, R. A., Jr., C. Landsea, M. Mayfield, J. Laver, and R. Pasch, 2005, Hurricanes and global warming, Bull. Am. Meteorol. Soc., 86, 1571-1575.
Pielke, R. A., Jr. 2005. Are there trends in hurricane destruction? Nature, Brief Communications Arising 438 E11
Trenberth, K. 2005. Uncertainty in hurricanes and global warming, Science, 308, 1753-1754.
Webster, P. J., G. J. Holland, J. A. Curry, and H.-R. Change, 2005. Changes in Tropical Cyclone Number, Duration, and Intensity in a Warming Environment, Science, 309, 1844-1846.
Southeast Texas is still recovering from Harvey. Now, the entire state of Florida may face great threat from Irma. And another big one has formed in the Northern Atlantic Ocean. Many are wondering whether or not this series of events is a direct result of climate change. Well, there is still a scientific debate on this. Here is the first paragraph from our study on understanding perceptions of changing hurricane strength (Shao et al. 2017 a):
"Climate change is one of the most complicated issues facing society today. Varying levels of change have been observed at the continental, regional, and ocean basin scale (IPCC, 2013), yet the specific factors driving these changes are only partly understood (Schneider, 2006). The relationship between climate change and hurricane activity in the Atlantic basin is a much debated topic and it is clearly one of the uncertainties in our future climate. For example, there has been an increase in the number and intensity of major hurricanes in the Atlantic basin that began in 1995 (Goldenberg et al., 2001; Pielke et al., 2005; Webster et al., 2005). One possible explanation for this upward trend of Atlantic hurricane activity is the increase of sea surface temperature (SST) driven by greenhouse gas forcing (Elsner, 2006; Emanuel, 2005; Holland & Webster, 2007; Webster et al., 2005). In contrast, there is another possible explanation that attributes the uptick in Atlantic hurricane activity since 1995 to multi-decadal climate variability and its induced increase of sea surface temperature driven primarily by the Atlantic Multi-decadal Oscillation (AMO). AMO as an ocean current could affect the sea surface temperature and thus in turn affect the hurricane activity (Senkbeil et al., 2011). It is premature to directly link it with climate change (Landsea, 2005; Landsea et al., 2006; Pielke et al., 2005)."
Here is a Washington Post piece explaining the science behind the recent U.S. hurricane history.
11 years ago, Al Gore opened many people's eyes to global warming in the Academy Award- winning An Inconvenient Truth. It, in conjunction with the Nobel Peace prize, managed to bring universal attention to this grand issue facing the entire humanity. The American public concern achieved a peak in 2006-07. Fast forward to 2017, global warming is still being denied by many high-profile politicians in the U.S. Al Gore made a sequel to keep the public updated with recent developments in the natural and political landscapes of global warming.
NYT reviews this new documentary.