Changes in Atlantic major hurricane frequency since the late-19th century

Atlantic hurricanes are a major hazard to life and property, and a topic of intense scientific interest. Historical changes in observing practices limit the utility of century-scale records of Atlantic major hurricane frequency. To evaluate past changes in frequency, we have here developed a homogenization method for Atlantic hurricane and major hurricane frequency over 1851–2019. We find that recorded century-scale increases in Atlantic hurricane and major hurricane frequency, and associated decrease in USA hurricanes strike fraction, are consistent with changes in observing practices and not likely a true climate trend. After homogenization, increases in basin-wide hurricane and major hurricane activity since the 1970s are not part of a century-scale increase, but a recovery from a deep minimum in the 1960s–1980s. We suggest internal (e.g., Atlantic multidecadal) climate variability and aerosol-induced mid-to-late-20th century major hurricane frequency reductions have probably masked century-scale greenhouse-gas warming contributions to North Atlantic major hurricane frequency.

Simulating the global economic ripples after a major hurricane — the case of Hurricane Sandy

Tropical cyclones range among the most severe disasters on Earth. Their economic repercussions along the supply and trade network also affect remote economies that are not directly affected. To find these repercussions in data is challenging due to the strong volatility of economic interactions. Numerical simulations can help to identify these ripples by approaching the problem from an exploratory angle isolating the effect of interest. We here simulate possible global repercussions for the example case of Hurricane Sandy (2012) using the shock-propagation model Acclimate. It models the behaviour of over 7,000 regional economic sectors, interlinked through about 1.8 million trade relations. The modeled shock yields a global three-phase ripple: an initial demand reduction and price decrease, followed by a supply shortage with increasing prices, and finally a recovery phase. Regions with strong trade relations to the US experience stronger magnitudes of the ripple. A dominating demand reduction or supply shortage leads to overall consumption gains or losses of a region, respectively. Throughout the three phases the model suggests overall a global consumption loss (~ 0.03%) with the strongest impact onto the US itself (~ 0.14%).

Predicting Major Storm Surge Levels

The National Atmospheric and Oceanic Administration (NOAA) calculates the surge probability distribution along the coast from their long-term tidal stations. This process is sufficient for predicting the surge from common storms but tends to underestimate large surges. Across 23 long-term tidal stations along the East Coast of the United States, 100-year surges were observed 49 times, although they should have occurred only 23 times. We hypothesize that these 100-year surges are not the tail outcome from common storms but are actually caused by major hurricanes. Matching these 100-year surges with major hurricanes revealed that major hurricanes caused 43 of the 49 surges. We consequently suggest a revised approach to estimating the surge probability distribution. We used tidal data to estimate the probability of common surges but analyzed major hurricane surges separately, using the return rate of major hurricanes and the observed surge from each major hurricane to predict hurricane surges. The revision reveals that expected coastal flooding damage is higher than we thought, especially in the southeast United States.

Colonial Debts

With the largest municipal debt in US history and a major hurricane that destroyed much of the archipelago's infrastructure, Puerto Rico has emerged as a key site for the exploration of neoliberalism and disaster capitalism. In Colonial Debts Rocío Zambrana develops the concept of neoliberal coloniality in light of Puerto Rico's debt crisis. Drawing on decolonial thought and praxis, Zambrana shows how debt functions as an apparatus of predation that transforms how neoliberalism operates. Debt functions as a form of coloniality, intensifying race, gender, and class hierarchies in ways that strengthen the colonial relationship between Puerto Rico and the United States. Zambrana also examines the transformation of protest in Puerto Rico. From La Colectiva Feminista en Construcción's actions, long-standing land rescue/occupation in the territory, to the July 2019 protests that ousted former governor Ricardo “Ricky” Rosselló, protests pursue variations of decolonial praxis that subvert the positions of power that debt installs. As Zambrana demonstrates, debt reinstalls the colonial condition and adapts the racial/gender order essential to it, thereby emerging as a key site for political-economic subversion and social rearticulation.

Recent Advances in Our Understanding of Tropical Cyclone Intensity Change Processes from Airborne Observations

Recent (past ~15 years) advances in our understanding of tropical cyclone (TC) intensity change processes using aircraft data are summarized here. The focus covers a variety of spatiotemporal scales, regions of the TC inner core, and stages of the TC lifecycle, from preformation to major hurricane status. Topics covered include (1) characterizing TC structure and its relationship to intensity change; (2) TC intensification in vertical shear; (3) planetary boundary layer (PBL) processes and air–sea interaction; (4) upper-level warm core structure and evolution; (5) genesis and development of weak TCs; and (6) secondary eyewall formation/eyewall replacement cycles (SEF/ERC). Gaps in our airborne observational capabilities are discussed, as are new observing technologies to address these gaps and future directions for airborne TC intensity change research.

A Machine Learning Based Ensemble Forecasting Optimization Algorithm for Preseason Prediction of Atlantic Hurricane Activity

In this study, nine different statistical models are constructed using different combinations of predictors, including models with and without projected predictors. Multiple machine learning (ML) techniques are employed to optimize the ensemble predictions by selecting the top performing ensemble members and determining the weights for each ensemble member. The ML-Optimized Ensemble (ML-OE) forecasts are evaluated against the Simple-Averaging Ensemble (SAE) forecasts. The results show that for the response variables that are predicted with significant skill by individual ensemble members and SAE, such as Atlantic tropical cyclone counts, the performance of SAE is comparable to the best ML-OE results. However, for response variables that are poorly modeled by individual ensemble members, such as Atlantic and Gulf of Mexico major hurricane counts, ML-OE predictions often show higher skill score than individual model forecasts and the SAE predictions. However, neither SAE nor ML-OE was able to improve the forecasts of the response variables when all models show consistent bias. The results also show that increasing the number of ensemble members does not necessarily lead to better ensemble forecasts. The best ensemble forecasts are from the optimally combined subset of models.

Changes in Atlantic Major Hurricane Frequency Since the Late-19th Century

Atlantic hurricanes are a major hazard to life and property1,2,3, and a topic of intense scientific interest4,5,6. Historical changes in observing practices limit the utility of century-scale records of Atlantic major hurricane frequency7-13. To evaluate past changes in frequency, we have here developed a homogenization method for Atlantic hurricane and major hurricane frequency over 1851-2019. We find that recorded century-scale increases in Atlantic hurricane and major hurricane frequency, and associated decrease in USA hurricanes strike fraction, are consistent with changes in observing practices and not likely a true climate trend. After homogenization, increases in basin-wide hurricane and major hurricane activity since the 1970s14-15 are not part of a century-scale increase, but a recovery from a deep minimum in the 1960s-1980s. These results support the notion that internal climate variability and aerosol-induced mid-to-late-20th century major hurricane frequency reductions16-24 have probably masked century-scale greenhouse-gas warming contributions to North Atlantic major hurricane frequency.