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1.
Proc Natl Acad Sci U S A ; 121(15): e2400292121, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38557181

RESUMO

Cyclone Jasper struck northern Queensland in mid-December, 2023, causing extensive flooding stemming from torrential rain. Many stations reported rainfall totals exceeding 1 m, and a few surpassed 2 m, possibly making Jasper the wettest tropical cyclone in Australian history. To be better prepared for events like Jasper, it is useful to estimate the probability of rainfall events of Jasper's magnitude and how that probability is likely to evolve as climate warms. To make such estimates, we apply an advanced tropical cyclone downscaling technique to nine global climate models, generating a total of 27,000 synthetic tropical cyclones each for the climate of the recent past and that of the end of this century. We estimate that the annual probability of 1 m of rain from tropical cyclones at Cairns increases from about 0.8% at the end of the 20th century to about 2.3% at the end of the 21st, a factor of almost three. Interpolating frequency to the year 2023 suggests that the current annual probability of Jasper's rainfall is about 1.2%, about a 50% increase over that of the year 2000. Further analysis suggests that the primary causes of increasing rainfall are stronger cyclones and a moister atmosphere.

2.
Proc Natl Acad Sci U S A ; 120(26): e2301664120, 2023 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-37339203

RESUMO

Turbulence-enhanced mixing of upper ocean heat allows interaction between the tropical atmosphere and cold water masses that impact climate at higher latitudes thereby regulating air-sea coupling and poleward heat transport. Tropical cyclones (TCs) can drastically enhance upper ocean mixing and generate powerful near-inertial internal waves (NIWs) that propagate down into the deep ocean. Globally, downward mixing of heat during TC passage causes warming in the seasonal thermocline and pumps 0.15 to 0.6 PW of heat into the unventilated ocean. The final distribution of excess heat contributed by TCs is needed to understand subsequent consequences for climate; however, it is not well constrained by current observations. Notably, whether or not excess heat supplied by TCs penetrates deep enough to be kept in the ocean beyond the winter season is a matter of debate. Here, we show that NIWs generated by TCs drive thermocline mixing weeks after TC passage and thus greatly deepen the extent of downward heat transfer induced by TCs. Microstructure measurements of the turbulent diffusivity ([Formula: see text]) and turbulent heat flux (J[Formula: see text]) in the Western Pacific before and after the passage of three TCs indicate that mean thermocline values of [Formula: see text] and J[Formula: see text] increased by factors of 2 to 7 and 2 to 4 (95% confidence level), respectively, after TC passage. Excess mixing is shown to be associated with the vertical shear of NIWs, demonstrating that studies of TC-climate interactions ought to represent NIWs and their mixing to accurately capture TC effects on background ocean stratification and climate.

3.
Proc Natl Acad Sci U S A ; 120(33): e2209631120, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37549274

RESUMO

Most current climate models predict that the equatorial Pacific will evolve under greenhouse gas-induced warming to a more El Niño-like state over the next several decades, with a reduced zonal sea surface temperature gradient and weakened atmospheric Walker circulation. Yet, observations over the last 50 y show the opposite trend, toward a more La Niña-like state. Recent research provides evidence that the discrepancy cannot be dismissed as due to internal variability but rather that the models are incorrectly simulating the equatorial Pacific response to greenhouse gas warming. This implies that projections of regional tropical cyclone activity may be incorrect as well, perhaps even in the direction of change, in ways that can be understood by analogy to historical El Niño and La Niña events: North Pacific tropical cyclone projections will be too active, North Atlantic ones not active enough, for example. Other perils, including severe convective storms and droughts, will also be projected erroneously. While it can be argued that these errors are transient, such that the models' responses to greenhouse gases may be correct in equilibrium, the transient response is relevant for climate adaptation in the next several decades. Given the urgency of understanding regional patterns of climate risk in the near term, it would be desirable to develop projections that represent a broader range of possible future tropical Pacific warming scenarios-including some in which recent historical trends continue-even if such projections cannot currently be produced using existing coupled earth system models.

4.
Glob Chang Biol ; 30(3): e17232, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38462701

RESUMO

Driven by climate change, tropical cyclones (TCs) are predicted to change in intensity and frequency through time. Given these forecasted changes, developing an understanding of how TCs impact insular wildlife is of heightened importance. Previous work has shown that extreme weather events may shape species distributions more strongly than climatic averages; however, given the coarse spatial and temporal scales at which TC data are often reported, the influence of TCs on species distributions has yet to be explored. Using TC data from the National Hurricane Center, we developed spatially and temporally explicit species distribution models (SDMs) to examine the role of TCs in shaping present-day distributions of Puerto Rico's 10 Anolis lizard species. We created six predictor variables to represent the intensity and frequency of TCs. For each occurrence of a species, we calculated these variables for TCs that came within 500 km of the center of Puerto Rico and occurred within the 1-year window prior to when that occurrence was recorded. We also included predictor variables related to landcover, climate, topography, canopy cover and geology. We used random forests to assess model performance and variable importance in models with and without TC variables. We found that the inclusion of TC variables improved model performance for the majority of Puerto Rico's 10 anole species. The magnitude of the improvement varied by species, with generalist species that occur throughout the island experiencing the greatest improvements in model performance. Range-restricted species experienced small, almost negligible, improvements but also had more predictive models both with and without the inclusion of TC variables compared to generalist species. Our findings suggest that incorporating data on TCs into SDMs may be important for modeling insular species that are prone to experiencing these types of extreme weather events.


Assuntos
Tempestades Ciclônicas , Lagartos , Animais , Mudança Climática , Porto Rico , Animais Selvagens , Previsões
5.
Glob Chang Biol ; 30(5): e17317, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38747199

RESUMO

Each year, an average of 45 tropical cyclones affect coastal areas and potentially impact forests. The proportion of the most intense cyclones has increased over the past four decades and is predicted to continue to do so. Yet, it remains uncertain how topographical exposure and tree characteristics can mediate the damage caused by increasing wind speed. Here, we compiled empirical data on the damage caused by 11 cyclones occurring over the past 40 years, from 74 forest plots representing tropical regions worldwide, encompassing field data for 22,176 trees and 815 species. We reconstructed the wind structure of those tropical cyclones to estimate the maximum sustained wind speed (MSW) and wind direction at the studied plots. Then, we used a causal inference framework combined with Bayesian generalised linear mixed models to understand and quantify the causal effects of MSW, topographical exposure to wind (EXP), tree size (DBH) and species wood density (ρ) on the proportion of damaged trees at the community level, and on the probability of snapping or uprooting at the tree level. The probability of snapping or uprooting at the tree level and, hence, the proportion of damaged trees at the community level, increased with increasing MSW, and with increasing EXP accentuating the damaging effects of cyclones, in particular at higher wind speeds. Higher ρ decreased the probability of snapping and to a lesser extent of uprooting. Larger trees tended to have lower probabilities of snapping but increased probabilities of uprooting. Importantly, the effect of ρ decreasing the probabilities of snapping was more marked for smaller than larger trees and was further accentuated at higher MSW. Our work emphasises how local topography, tree size and species wood density together mediate cyclone damage to tropical forests, facilitating better predictions of the impacts of such disturbances in an increasingly windier world.


Assuntos
Tempestades Ciclônicas , Florestas , Árvores , Clima Tropical , Vento , Árvores/crescimento & desenvolvimento , Teorema de Bayes
6.
Proc Natl Acad Sci U S A ; 118(41)2021 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-34607948

RESUMO

The impacts of inland flooding caused by tropical cyclones (TCs), including loss of life, infrastructure disruption, and alteration of natural landscapes, have increased over recent decades. While these impacts are well documented, changes in TC precipitation extremes-the proximate cause of such inland flooding-have been more difficult to detect. Here, we present a latewood tree-ring-based record of seasonal (June 1 through October 15) TC precipitation sums (ΣTCP) from the region in North America that receives the most ΣTCP: coastal North and South Carolina. Our 319-y-long ΣTCP reconstruction reveals that ΣTCP extremes (≥0.95 quantile) have increased by 2 to 4 mm/decade since 1700 CE, with most of the increase occurring in the last 60 y. Consistent with the hypothesis that TCs are moving slower under anthropogenic climate change, we show that seasonal ΣTCP along the US East Coast are positively related to seasonal average TC duration and TC translation speed.

7.
Int Arch Occup Environ Health ; 96(3): 367-376, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36280602

RESUMO

OBJECTIVE: In recent times, increased rainfall from tropical cyclones due to climate change affects the agricultural sector, mainly the paddy fields. High windspeed with excessive rain causes lodging of paddy crops, which is difficult to harvest. Mechanized harvesting systems are ineffective in this situation due to waterlogging in the fields. Manual harvesting with a traditional sickle is the only way to harvest lodged crops to save food security crises and economic losses. Collecting the lodged paddy stems lying on the ground for harvesting manually is time-consuming and harvesters need to maintain an awkward posture for a prolonged period compared to harvesting un-lodged crops. METHODS: Seventy-five female harvesters aged 35-75 years were selected for the study from both lodged and un-lodged small-scale farming lands of Kerala, a southwestern coastal state of India. A comparative ergonomic assessment was conducted to measure body pain, perceived exertion, postural risks, and rate of production under both harvesting conditions. RESULTS: The harvesters reported significant higher rates of body pain, perceived exertion, high postural risks, and low productivity in lodged conditions compared to un-lodged condition. CONCLUSION: Harvesting lodged crops involves high risks with low productivity and needs immediate ergonomic design intervention for the well-being of the harvesters.


Assuntos
Tempestades Ciclônicas , Humanos , Feminino , Agricultura , Ergonomia , Índia , Dor
8.
Proc Natl Acad Sci U S A ; 117(46): 28692-28699, 2020 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-33144499

RESUMO

Strong institutions as well as economic development are generally understood to play critical roles in protecting societies from the adverse impacts of natural hazards, such as tropical cyclones. The independent effect of institutions on reducing these risks, however, has not been confirmed empirically in previous global studies. As a storm's path and intensity influence the severity of the damages and may be spatially correlated with human vulnerabilities, failing to accurately capture physical exposure in an econometric analysis may result in imprecise and biased estimates of the influence of the independent variables. Here, we develop an approach to control for physical exposure by spatially interacting meteorological and socioeconomic data for over 1,000 tropical cyclone disasters from 1979 to 2016. We find evidence that higher levels of national government effectiveness are associated with lower tropical cyclone mortality, even when controlling for average income and other socioeconomic conditions. Within countries, deaths are higher when strong winds are concentrated over areas of the country with elevated infant mortality rates, an indicator of institutional effectiveness through public service delivery. These results suggest that policies and programs to enhance institutional capacity and governance can support risk reduction from extreme weather events.


Assuntos
Tempestades Ciclônicas/mortalidade , Desastres , Desenvolvimento Econômico , Programas Governamentais , Governo , Humanos , Análise Espacial
9.
Proc Natl Acad Sci U S A ; 117(20): 10706-10714, 2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32366651

RESUMO

Owing to the limited length of observed tropical cyclone data and the effects of multidecadal internal variability, it has been a challenge to detect trends in tropical cyclone activity on a global scale. However, there is a distinct spatial pattern of the trends in tropical cyclone frequency of occurrence on a global scale since 1980, with substantial decreases in the southern Indian Ocean and western North Pacific and increases in the North Atlantic and central Pacific. Here, using a suite of high-resolution dynamical model experiments, we show that the observed spatial pattern of trends is very unlikely to be explained entirely by underlying multidecadal internal variability; rather, external forcing such as greenhouse gases, aerosols, and volcanic eruptions likely played an important role. This study demonstrates that a climatic change in terms of the global spatial distribution of tropical cyclones has already emerged in observations and may in part be attributable to the increase in greenhouse gas emissions.

10.
Proc Natl Acad Sci U S A ; 117(26): 14751-14755, 2020 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-32541031

RESUMO

The total amount of rainfall associated with tropical cyclones (TCs) over a given region is proportional to rainfall intensity and the inverse of TC translation speed. Although the contributions of increase in rainfall intensity to larger total rainfall amounts have been extensively examined, observational evidence on impacts of the recently reported but still debated long-term slowdown of TCs on local total rainfall amounts is limited. Here, we find that both observations and the multimodel ensemble of Global Climate Model simulations show a significant slowdown of TCs (11% in observations and 10% in simulations, respectively) from 1961 to 2017 over the coast of China. Our analyses of long-term observations find a significant increase in the 90th percentile of TC-induced local rainfall totals and significant inverse relationships between TC translation speeds and local rainfall totals over the study period. The study also shows that TCs with lower translation speed and higher rainfall totals occurred more frequently after 1990 in the Pearl River Delta in southern China. Our probability analysis indicates that slow-moving TCs are more likely to generate heavy rainfall of higher total amounts than fast-moving TCs. Our findings suggest that slowdown of TCs tends to elevate local rainfall totals and thus impose greater flood risks at the regional scale.

11.
J Am Soc Nephrol ; 33(9): 1757-1766, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35835459

RESUMO

BACKGROUND: Hurricanes are severe weather events that can disrupt power, water, and transportation systems. These disruptions may be deadly for patients requiring maintenance dialysis. We hypothesized that the mortality risk among patients requiring maintenance dialysis would be increased in the 30 days after a hurricane. METHODS: Patients registered as requiring maintenance dialysis in the United States Renal Data System who initiated treatment between January 1, 1997 and December 31, 2017 in one of 108 hurricane-afflicted counties were followed from dialysis initiation until transplantation, dialysis discontinuation, a move to a nonafflicted county, or death. Hurricane exposure was determined as a tropical cyclone event with peak local wind speeds ≥64 knots in the county of a patient's residence. The risk of death after the hurricane was estimated using time-varying Cox proportional hazards models. RESULTS: The median age of the 187,388 patients was 65 years (IQR, 53-75) and 43.7% were female. There were 27 hurricanes and 105,398 deaths in 529,339 person-years of follow-up on dialysis. In total, 29,849 patients were exposed to at least one hurricane. Hurricane exposure was associated with a significantly higher mortality after adjusting for demographic and socioeconomic covariates (hazard ratio, 1.13; 95% confidence interval, 1.05 to 1.22). The association persisted when adjusting for seasonality. CONCLUSIONS: Patients requiring maintenance dialysis have a higher mortality risk in the 30 days after a hurricane.


Assuntos
Tempestades Ciclônicas , Diálise Renal , Insuficiência Renal , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Rim , Modelos de Riscos Proporcionais , Estados Unidos/epidemiologia , Insuficiência Renal/terapia
12.
Int J Biometeorol ; 67(8): 1323-1333, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37280444

RESUMO

Defoliation caused by strong tropical cyclones can modify the partitioning of incident solar radiation between the sensible, latent, and substrate heat fluxes. While previous work has shown hurricane defoliation to warm near-surface air temperature along its track, this study more directly contextualizes the warming to human heat stress and exposure via the heat index (HI). For this case study, the spatial extent and temporal persistence of defoliation produced by Hurricane Laura (2020) in southwestern Louisiana was characterized using the normalized difference vegetation index (NDVI). The defoliated land surface was then assimilated into the Weather Research and Forecasting (WRF) model version 4.2 and compared to a control, normal-foliage simulation for the 30 days following landfall. Over southwest Louisiana, the largest HI increase occurred at 0600 UTC (1:00 AM LT) with an average increase of + 0.25 °C, and the exposure time to HI ≥ 30 °C increased by 8.1% after accounting for the defoliated landscape. Meanwhile, Cameron, Louisiana, the site of Laura's landfall where defoliation was most severe, cumulatively experienced an extra 33 h of HI values exceeding 26 °C, while mean HI increased by 1.2 °C at 0300 UTC. Additional WRF experiments were performed with altered "landfall" years of 2017 and 2018 to determine the sensitivity of defoliation-driven HI changes to the ambient synoptic conditions. While synoptic conditions modulated the magnitude of increase, HIs nonetheless experienced statistically significant increases in both hypothetical "landfall" years. Such findings are valuable for emergency managers and community health officials because overnight minimum temperatures are a strong indicator of heat mortality.


Assuntos
Tempestades Ciclônicas , Transtornos de Estresse por Calor , Humanos , Tempo (Meteorologia) , Modelos Teóricos , Simulação por Computador
13.
Proc Natl Acad Sci U S A ; 116(16): 7732-7737, 2019 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-30936316

RESUMO

Volcanic eruptions can affect global climate through changes in atmospheric and ocean circulation, and therefore could impact tropical cyclone (TC) activity. Here, we use ensemble simulations performed with an Earth System Model to investigate the impact of strong volcanic eruptions occurring in the tropical Northern (NH) and Southern (SH) Hemisphere on the large-scale environmental factors that affect TCs. Such eruptions cause a strong asymmetrical hemispheric cooling, either in the NH or SH, which shifts the Intertropical Convergence Zone (ITCZ) southward or northward, respectively. The ITCZ shift and the associated surface temperature anomalies then cause changes to the genesis potential indices and TC potential intensity. The effect of the volcanic eruptions on the ITCZ and hence on TC activity lasts for at least 4 years. Finally, our analysis suggests that volcanic eruptions do not lead to an overall global reduction in TC activity but rather a redistribution following the ITCZ movement. On the other hand, the volcanically induced changes in El Niño-Southern Oscillation (ENSO) or sea-surface temperature do not seem to have a significant impact on TC activity as previously suggested.

14.
Environ Monit Assess ; 194(9): 668, 2022 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-35962808

RESUMO

The earth is experiencing the impact of climate change due to global warming. Lake ecosystems are no exception and are expected to cope with the consequences of extreme climatic events (hereafter ECE), such as storms, floods, and droughts. These events have significant potential to alter the hydrological characteristics (HC) influencing the physical, chemical, and biological behavior of lake ecosystems. Considering such ecosystem's high-value services and benefits, it is the need of the hour to monitor and evaluate the impact of ECE on lake ecosystems. The second-largest brackish water system in the world, Chilika Lake, situated at the shore of the Bay of Bengal (BoB), has encountered a total of 1306 tropical cyclonic storms in the last 131 years. Since most tropical cyclones lead to heavy floods, this could be devastating for the ecosystem and its services. Hence, in order to bridge the knowledge gap, the present study was carried out to understand its impact, based on the available field data of more than two decades (1999 to 2020) and historical records of ECE and HC since 1840 and 1915 respectively from the literature. The study revealed that the ECE attributed to short-term changes in HC which were reflected through an immediate change in trophic state index (TSI, indicator of lake health) and trophic switchover (net autotrophic to heterotrophic) between net sink and source of carbon dioxide (CO2) in specific regions. This study showed that both the ECE as well as a human intervention (opening of the new mouth) had an integrated role in the maintenance of HC within the lake as indicated by the variability of salinity level which is the lifeblood of the Chilika. Major ECE factors which controlled the salinity in Chilika were freshwater input through cyclone-induced flash flooding and seawater exchange through varying mouth conditions, i.e., opening of the new mouth, shifting, and widening of existing mouths due to cyclone impacts. The impact of the cyclone-induced flash flood was sustained for a couple of months to years depending on the magnitudes. As evidenced from the historical data available for ECEs, respective mouth variability, and salinity regime, ECE was found to maintain the salinity regime of the lake in the long run. Since the hydrological characteristics are found to be maintained through ECE as well as human intervention, the Chilika Lake recorded a substantial increase in fishery, seagrasses, Irrawaddy dolphins, migratory birds, and reduction in weed infestation. This study highlights the importance of historical data collection through a continuous systematic lake monitoring program which would enable understanding the ecosystem functioning and behavior with ECE-induced changing environmental conditions which is also a key component for formulating a sustainable management action plan for lake ecosystems around the globe.


Assuntos
Ecossistema , Lagos , Ásia , Monitoramento Ambiental , Humanos , Água do Mar
15.
Proc Natl Acad Sci U S A ; 115(12): 2930-2935, 2018 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-29507192

RESUMO

Idealized simulations of tropical moist convection have revealed that clouds can spontaneously clump together in a process called self-aggregation. This results in a state where a moist cloudy region with intense deep convection is surrounded by extremely dry subsiding air devoid of deep convection. Because of the idealized settings of the simulations where it was discovered, the relevance of self-aggregation to the real world is still debated. Here, we show that self-aggregation feedbacks play a leading-order role in the spontaneous genesis of tropical cyclones in cloud-resolving simulations. Those feedbacks accelerate the cyclogenesis process by a factor of 2, and the feedbacks contributing to the cyclone formation show qualitative and quantitative agreement with the self-aggregation process. Once the cyclone is formed, wind-induced surface heat exchange (WISHE) effects dominate, although we find that self-aggregation feedbacks have a small but nonnegligible contribution to the maintenance of the mature cyclone. Our results suggest that self-aggregation, and the framework developed for its study, can help shed more light into the physical processes leading to cyclogenesis and cyclone intensification. In particular, our results point out the importance of the longwave radiative cooling outside the cyclone.

16.
Proc Natl Acad Sci U S A ; 115(45): 11460-11464, 2018 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-30348766

RESUMO

Predicting North Atlantic hurricane activity months in advance is of great potential societal significance. The ocean temperature, both in terms of North Atlantic/tropical averages and upper ocean heat content, is demonstrated to be a significant predictor. To investigate the relationship between the thermal state of the Atlantic Ocean and the tropical cyclone (TC) activity in terms of accumulated cyclone energy (ACE), we use observed 1980-2015 TC records and a 1/4° resolution global ocean reanalysis. This paper highlights the nonlocal effect associated with eastern Atlantic Ocean temperature, via a reduction of wind shear, and provides additional predictive skill of TC activity, when considering subsurface temperature instead of sea surface temperature (SST) only. The most active TC seasons occur for lower than normal wind shear conditions over the main development region, which is also driven by reduced trade wind strength. A significant step toward operationally reliable TC activity predictions is gained after including upper ocean mean temperatures over the eastern Atlantic domain. Remote effects are found to provide potential skill of ACE up to 3 months in advance. These results indicate that consideration of the upper 40-m ocean average temperature improves upon a prediction of September Atlantic hurricane activity using only SST.


Assuntos
Tempestades Ciclônicas/estatística & dados numéricos , Previsões/métodos , Modelos Estatísticos , Água do Mar/análise , Oceano Atlântico , Humanos , Estações do Ano , Temperatura , Vento
17.
Proc Natl Acad Sci U S A ; 115(45): 11543-11548, 2018 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-30348774

RESUMO

Determination of long-term tropical cyclone (TC) variability is of enormous importance to society; however, changes in TC activity are poorly understood owing to discrepancies among various datasets and limited span of instrumental records. While the increasing intensity and frequency of TCs have been previously documented on a long-term scale using various proxy records, determination of their poleward migration has been based mostly on short-term instrumental data. Here we present a unique tree-ring-based approach for determination of long-term variability in TC activity via forest disturbance rates in northeast Asia (33-45°N). Our results indicate significant long-term changes in TC activity, with increased rates of disturbances in the northern latitudes over the past century. The disturbance frequency was stable over time in the southern latitudes, however. Our findings of increasing disturbance frequency in the areas formerly situated at the edge of TC activity provide evidence supporting the broad relevance of poleward migration of TCs. Our results significantly enhance our understanding of the effects of climate change on TCs and emphasize the need for determination of long-term variation of past TC activity to improve future TC projections.

18.
Mol Ecol ; 29(14): 2583-2597, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32573031

RESUMO

Expansion of many tree species lags behind climate change projections. Extreme storms can rapidly overcome this lag, especially for coastal species, but how will storm-driven expansion shape intraspecific genetic variation? Do storms provide recruits only from the nearest sources, or from more distant sources? Answers to these questions have ecological and evolutionary implications, but empirical evidence is absent from the literature. In 2017, Hurricane Irma provided an opportunity to address this knowledge gap at the northern range limit of the neotropical black mangrove (Avicennia germinans) on the Atlantic coast of Florida, USA. We observed massive post-hurricane increases in beach-stranded A. germinans propagules at, and past, this species' present day range margin when compared to a previously surveyed nonhurricane year. Yet, propagule dispersal does not guarantee subsequent establishment and reproductive success (i.e., effective dispersal). We also evaluated prior effective dispersal along this coastline with isolated A. germinans trees identified beyond the most northern established population. We used 12 nuclear microsatellite loci to genotype 896 hurricane-driven drift propagules from nine sites and 10 isolated trees from four sites, determined their sources of origin, and estimated dispersal distances. Almost all drift propagules and all isolated trees came from the nearest sources. This research suggests that hurricanes are a prerequisite for poleward range expansion of a coastal tree species and that storms can shape the expanding gene pool by providing almost exclusively range-margin genotypes. These insights and empirical estimates of hurricane-driven dispersal distances should improve our ability to forecast distributional shifts of coastal species.


Assuntos
Avicennia/genética , Tempestades Ciclônicas , Variação Genética , Mudança Climática , Florida , Repetições de Microssatélites , Dispersão Vegetal
19.
Geophys Res Lett ; 47(14): e2020GL088662, 2020 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-32999514

RESUMO

Future changes in tropical cyclone properties are an important component of climate change impacts and risk for many tropical and midlatitude countries. In this study we assess the performance of a multimodel ensemble of climate models, at resolutions ranging from 250 to 25 km. We use a common experimental design including both atmosphere-only and coupled simulations run over the period 1950-2050, with two tracking algorithms applied uniformly across the models. There are overall improvements in tropical cyclone frequency, spatial distribution, and intensity in models at 25 km resolution, with several of them able to represent very intense storms. Projected tropical cyclone activity by 2050 generally declines in the South Indian Ocean, while changes in other ocean basins are more uncertain and sensitive to both tracking algorithm and imposed forcings. Coupled models with smaller biases suggest a slight increase in average TC 10 m wind speeds by 2050.

20.
Proc Natl Acad Sci U S A ; 114(45): 11861-11866, 2017 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-29078274

RESUMO

The flood hazard in New York City depends on both storm surges and rising sea levels. We combine modeled storm surges with probabilistic sea-level rise projections to assess future coastal inundation in New York City from the preindustrial era through 2300 CE. The storm surges are derived from large sets of synthetic tropical cyclones, downscaled from RCP8.5 simulations from three CMIP5 models. The sea-level rise projections account for potential partial collapse of the Antarctic ice sheet in assessing future coastal inundation. CMIP5 models indicate that there will be minimal change in storm-surge heights from 2010 to 2100 or 2300, because the predicted strengthening of the strongest storms will be compensated by storm tracks moving offshore at the latitude of New York City. However, projected sea-level rise causes overall flood heights associated with tropical cyclones in New York City in coming centuries to increase greatly compared with preindustrial or modern flood heights. For the various sea-level rise scenarios we consider, the 1-in-500-y flood event increases from 3.4 m above mean tidal level during 1970-2005 to 4.0-5.1 m above mean tidal level by 2080-2100 and ranges from 5.0-15.4 m above mean tidal level by 2280-2300. Further, we find that the return period of a 2.25-m flood has decreased from ∼500 y before 1800 to ∼25 y during 1970-2005 and further decreases to ∼5 y by 2030-2045 in 95% of our simulations. The 2.25-m flood height is permanently exceeded by 2280-2300 for scenarios that include Antarctica's potential partial collapse.


Assuntos
Mudança Climática , Conservação dos Recursos Naturais , Tempestades Ciclônicas , Inundações , Desastres , Modelos Teóricos , Cidade de Nova Iorque , Oceanos e Mares
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