Image courtesy of Proceedings of the Royal Society B. Months of transmission suitability in the Americas of dengue (left) and Zika (right).

GAINESVILLE, FL – A University of Florida Medical Geography researcher recently participated in a study that found that current estimates of Zika virus transmission vastly over predict its possible range. Temperature is a major driver of vector-borne disease transmission, but current transmission models rely on untested assumptions about life history of Zika infected Aedes aegypti mosquitoes. Previous models of Zika transmission were based on similarities between Zika and dengue fever.

The study, led by Dr. Courtney Murdock from the University of Georgia, examined the influence of temperature on Zika transmission in lab-reared Aedes mosquitoes at eight different constant temperatures. Zika transmits optimally at a temperature similar to dengue, but the lowest possible transmission temperature of Zika is 5 degrees centigrade warmer than dengue. As global average temperatures increase under climate change the range of Zika will expand north and into longer transmission seasons, but some areas that are currently suitable for Zika transmission will no longer support transmission.

UF Medical Geography professor Dr. Sadie Ryan used the temperature relationships to make updated models and maps, which she compared with previous transmission models. “These maps show that the predicted area for year round risk of Zika transmission is over 6 million square kilometers smaller than previous models would predict,” said Ryan. “This shows that Zika is not dengue and we need to have specific transmission models for specific diseases.”

The findings have been published in a paper titled Temperature drives Zika virus transmission: evidence from empirical and mathematical models in Proceedings of the Royal Society B.

The study was part of a collaboration between UF’s Dr. Sadie Ryan and Dr. Calistus Ngonghala, the CDC Southeastern Center of Excellence in Vector Borne Diseases, the University of Georgia, as well as investigators from Stanford University and Harvard Medical School.

Image credit: Ms. Catherine Lippi. This study was conducted with epidemiological data collected in Barbados, an island located in the Caribbean (left). Population in Barbados (middle) and elevation on the island (right) are shown, as well as the location of the two meteorological stations that provided climate data for the study.

GAINESVILLE, FL – Medical Geography researchers from the University of Florida recently participated in a study that successfully predicted dengue fever outbreaks on the Caribbean island of Barbados, using climate data. This paper is part of a special issue of PLOS MEDICINE, focusing on the impacts of climate change on health, and is a result of an unprecedented collaborative project, funded by USAID to address climate driven health impacts in the Caribbean.

The study, led by Dr. Rachel Lowe from the London School of Hygiene and Tropical Medicine, tested whether dengue outbreaks in the Caribbean island of Barbados could be predicted using weather station data for temperature and a precipitation index (Standardized Precipitation Index- SPI) used to monitor drought and extreme rainfall. Using data from June 1999 to May 2016, researchers found that the statistical model was able to successfully predict months with dengue outbreaks versus non-outbreaks in most years.
Dengue fever is spread by Aedes sp. mosquitos and infects over 350 million people each year, resulting in 25,000 deaths globally and costing households, governments, and businesses over $45 million annually. In recent decades, the disease has emerged as a major public health threat, and as many as 2 in 5 people globally are at risk of contracting dengue fever.

UF Medical Geography professor Dr. Sadie Ryan and doctoral student Ms. Catherine Lippi collaborated on models that explored the delayed effect of climate indicators like extreme rainfall and drought on future outbreaks of dengue fever on the Caribbean island.
“This study highlights the importance of keeping long term records of climate and health data so that we can learn about how a changing climate will impact our health and well-being in the future,” said Dr. Ryan.
The model found a sharp increase in disease transmission one to two months after extreme rainfall events, but a surprising result of the model was an increase in infections four to five months after a drought event. Lippi explained “During droughts, people store water in containers near their homes,” she said, “which creates the perfect habitat for Aedes mosquitos.” Senior author, Dr Stewart-Ibarra, from SUNY Upstate Medical University said she and others working on the project had heard from locals that this was a recurring trend but it wasn’t until they studied the data that they found it to be true. “Barbados is a water-scarce country. During periods of drought, people have to store water.”

The findings have been published in a paper titled Nonlinear and delayed impacts of climate on dengue risk in Barbados: A modelling study in PLOS Medicine.

The study was part of a collaboration between UF and the Caribbean Agency for Public Health, the Pan American Health Organization, the Caribbean Institute for Meteorology and Hydrology, as well as investigators from the London School of Hygiene and Tropical Medicine, SUNY Upstate Medical University, and the Escuela Superior Politecnica del Litoral of Ecuador.

DOWHANIUK, GOLDMANRYAN – Park isolation in anthropogenic landscapes: land change and livelihoods at park boundaries in the African Albertine Rift

Jonathan Salerno, Colin A. Chapman, Jeremy E. Diem, Nicholas Dowhaniuk, Abraham Goldman, Catrina A. MacKenzie, Patrick Aria Omeja, Michael W. Palace, Rafael Reyna-Hurtado, Sadie J. Ryan, Joel Hartter

Article first published online: 14 NOV 2017 Regional Environmental Change

DOI: 10.1007/s10113-017-1250-1

ABSTRACT: Landscapes are changing rapidly in regions where rural people live adjacent to protected parks and reserves. This is the case in highland East Africa, where many parks are increasingly isolated in a matrix of small farms and settlements. In this review, we synthesize published findings and extant data sources to assess the processes and outcomes of park isolation, with a regional focus on people’s livelihoods at park boundaries in the Ugandan Albertine Rift. The region maintains exceptionally high rural population density and growth and is classified as a global biodiversity hotspot. In addition to the impacts of increasing numbers of people, our synthesis highlights compounding factors—changing climate, increasing land value and variable tenure, and declining farm yields—that accelerate effects of population growth on park isolation and widespread landscape change. Unpacking these processes at the regional scale identifies outcomes of isolation in the unprotected landscape—high frequency of human-wildlife conflict, potential for zoonotic disease transmission, land and resource competition, and declining wildlife populations in forest fragments. We recommend a strategy for the management of isolated parks that includes augmenting outreach by park authorities and supporting community needs in the human landscape, for example through healthcare services, while also maintaining hard park boundaries through traditional protectionism. Even in cases where conservation refers to biodiversity in isolated parks, landscape strategies must include an understanding of the local livelihood context in order to ensure long-term sustainable biodiversity protection.

Read the full publication at Regional Environmental Change






Wild Futures in Conservation and Climate

November 9th, 3pm, Rion Ballroom, Reitz Union

Mac Stone, Conservation Photographer, Author and Educator

Title: Dispatches from the Field – A World in Flux

Mac Stone travels the globe to bring back stories from the frontiers where mankind and the natural world collide. Copies of Mac’s book Everglades: America’s Wetland will be available to purchase.

Shaun Martin, Senior Director, Climate Change Adaptation, and Resilience at World Wildlife Fund

Title: Learning to Live with Climate Change

Shaun will discuss the need to consider climate change risks on biodiversity and natural resources and the necessary paradigm shift in conservation away from managing for persistence to facilitating change.

The Kevin and Jeannette Malone Distinguished Scholar Series began in 2014 with a generous donation for the purpose of bringing world class scholars and educational opportunities to the University of Florida. The invited scholars have been renowned experts in fields such as food security, sustainable development, climate and energy, wildlife and natural systems, resource policies, and other environmentally-focused research. In addition to delivering a lecture to both campus and the public, the scholars meet with students, faculty, and private industry partners to discuss their work, establish potential collaborations, and develop continuing relationships with the University of Florida.

Supplement your major with an understanding of the atmosphere and awareness of the societal impacts of natural hazards and climate change. The certificate is designed for students seeking employment as climatologists, broadcast meteorologists, water district managers, those interested in environmental issues, to prepare for graduate studies, or those who just love the weather.

ecological-modelingBUNTING, SOUTHWORTH – Utilization of the SAVANNA model to analyze future patterns of vegetation cover in Kruger National Park under changing climate

Erin L. Bunting, Timothy Fullman, Gregory Kiker, Jane Southworth

Article first published online: 17 OCT 2016 Ecological Modelling

DOI: 10.1016/j.ecolmodel.2016.09.012


Within southern Africa’s savanna ecosystems, woody and herbaceous species have differing growth characteristics that allow a tenuous co-existance. The high dependence of humans on the landscape, through agricultural production, tourism, and natural resource extraction makes understanding savanna vegetation dynamics essential. Studies analyzing resilience of savannas suggest potential state changes in vegetation structure from continuous grasslands with sporadic woody cover to less biologically productive landscapes. One of the biggest questions in this landscape is the impact of climate change. The spatially explicit SAVANNA model is used to analyze the impact of climate change on vegetation cover across Kruger National Park’s (KNP) main land system classifications (Satara, Skukuza, Letaba, and Phalaborwa). Manipulating climate inputs and management regimes allowed us to analyze the resilience of savanna vegetation under multiple Intergovernmental Panel on Climate Change (IPCC) scenarios. Trends in future climate indicate an increase in temperatures greater than 1.0 °Celsius and a slight decrease in precipitation by 2080. Model results indicate a long-term decrease in multiple size classes of vegetation across all the four land systems. However, the model runs show differing response to climate change between the woody and herbaceous cover types. Spatial trends across the park follow closely with the north-south climate gradient. The most spatially distinct land system was Skukuza, which exhibited some of the highest initial net primary production (NPP) values and also the greatest decreases in NPP into the future. While this region is projected to lose large proportions of its herbaceous and shrub vegetation it is projected to increase in tree green leaf, mostly related to increasing fine leaf vegetation (Acacia sp.). The northern land systems were already dominated by mopane, but under all model scenarios mopane will increase in Letaba and Phalaborwa. This mopane increase will offset the loss of herbaceous and shrub vegetation, resulting in little to no decrease in NPP across time for these land systems. This work illustrates that landscape resilience is not only impacted by the severity of changing climate but the degree to which we manage such systems.

Read the full publication at Ecological Modelling

MOSSA – How much is enough? An integrated examination of energy security, economic growth and climate change related to hydropower expansion in Brazil

Fernando Almeida Prado Jr., Simone Athayde, Joann Mossa, Stephanie Bohlman, Flavia Leite, Anthony Oliver-Smith

Article first published online: January 2016 Renewable and Sustainable Energy Reviews

DOI: 10.1016/j.rser.2015.09.050

ABSTRACT: Reconciling economic growth and energy supply with the reduction of greenhouse gas emissions and other goals for environmental protection is a major challenge for emerging economies such as Brazil. Establishing energy security standards consistent with realistic economic growth projections while considering climate change requires complex calculations and relies upon risky assumptions. Yet, such calculations and decisions must be made to avoid future energy shortages and economic crises. This paper discusses the current dilemma concerning planning and decision-making for the Brazilian electric sector considering the construction of hydroelectric power plants in the Amazon region, energy security requirements, projected economic growth and climate change feedbacks.

Read the full publication at Renewable and Sustainable Energy Reviews