The Climate CIRCulator is brought to you by The Pacific Northwest Climate Impacts Research Consortium (CIRC) and The Oregon Climate Change Research Institute (OCCRI).

Climate Patterns Impact Epidemics Beyond Current Season

A recent study found a connection between warm winters and influenza epidemics in successive years. Towers et al. (2013) investigated patterns of multiple strains of influenza in winter seasons from 1997-98 to 2012-13 in the US and found that a more severe and earlier onset epidemic of influenza was more likely to occur after a previous warm winter season. Transmissibility of influenza rapidly decreases in warm temperatures, which leads to fewer individuals infected by the illness, ultimately making them more susceptible in the succeeding winter. The authors suggest a mild (warmer than average) winter will significantly influence epidemic peak timing and growth rate in the following season.

Our interpretation of this article: it demonstrates a connection that may be very useful in mitigating severe influenza epidemics by implementing progressive vaccination programs in preparation for influenza seasons in the years following a mild winter. In an average year, more than 200,000 people are hospitalized and roughly 36,000 people die as a result of complications from influenza infection; warning of a particularly severe influenza season can decrease transmission and save lives. While the study demonstrated an intriguing connection between the temperatures in one winter and the severity of a flu outbreak the following winter, it did not address the possible results of a warming climate.
Towers, S., G. Chowell, R. Hameed, M. Jastrebski, M. Khan, J. Meeks, A. Mubayi, and G. Harris. 2013. Climate change and influenza: the likelihood of early and severe influenza seasons following warmer than average winters. PLOS Currents Influenza Edition 1. doi: 10.1371/currents.flu.3679

Large-Scale Ecosystem Resilience to Drought

Drought frequency and duration, along with temperature, are predicted to increase during this century in many regions of the world, including most of the Americas. With large regions of the globe (for example, United States and Australia), undergoing a decadal-scale drought during the beginning of the 21st century, we already have the opportunity to begin examining the response of biomes to a foreseeable future climate. A team of authors (Ponce Campos et al. 2013) has recently taken advantage of these large-scale droughts to look at the resilience of biomes to drought by examining carbon gain at the expense of water loss or water-use efficiency (WUE). The authors measured WUE as the ratio of above-ground net primary production to evapotranspiration for an ecosystem. Resilience was defined as the capacity for a system to absorb a drought disturbance and still be able to transition to a “common minimum native state” of WUE given subsequent water abundance. The authors separated wet and dry years, and showed that the wet-year WUE was the same irrespective of biome and whether the year was during the recent large-scale drought (2000-2009) or from the wetter preceding years (1975-1999). This implies that biomes exhibit resilience or the capacity to absorb drought disturbance and maintain eco-hydrologic function despite interannual climate variability.
Ponce Campos, G. E., and 19 coauthors. 2013. Ecosystem resilience despite large-scale altered hydroclimatic conditions. Nature Vol. 494, 349-352. doi:10.1038/nature11836.
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Photo Credit

Dudley Chelton is a Distinguished Professor in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University.

If interested in featuring your PNW photos contact Kim Carson at

Featured Researcher

CIRC investigator Dr. Jeffrey Bethel is an Assistant Professor in the College of Public Health and Human Sciences at OSU. Bethel’s primary research interests include infectious disease epidemiology, health effects of climate change, and disaster preparedness. Currently, his research group is working to identify populations vulnerable to natural and man-made disasters and to develop interventions to increase household- and community-level preparedness. He is also leading a study to identify risk factors for heat-related illness among farmworkers in Oregon, as outdoor workers have been identified as a population vulnerable to climate-related health effects. Bethel recently authored a chapter in the Northwest Climate Assessment Report on the health effects of climate change in the Northwest.

Managing for Carbon Sinks

A study by Post et al. (2012) discusses how land management practices can play a role in reducing atmospheric greenhouse gas concentrations. For example, forestry managers in the US can potentially increase storage of carbon dioxide by up to 740 million metric tons per year. For comparison, the average coal-fired power plant in the US produces more than 3.5 million metric tons of carbon per year. Converting farming practices to plant seeds directly into the soil (known as 'direct seeding') without requiring tillage is estimated to remove 1.22 metric tons of carbon dioxide equivalent per hectare per year. In the Pacific Northwest, a multi-university study, Regional Approaches to Climate Change - Pacific Northwest Agriculture (REACCH PNA), is investigating similar opportunities for dry-land wheat producers to increase carbon storage through direct seeding techniques and other farming practices. You can learn more about REACCH PNA here.
Post, W. M., R. C. Izaurralde, T. O. West, M. A. Liebig, and A. W. King. 2012. Management opportunities for enhancing terrestrial carbon dioxide sinks. Frontiers in Ecology and the Environment Vol 10.(10) 554-561. doi: 10.1890/120065.

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CO2 Sources and Sinks in North America

If we exclude the combustion of fossil fuels and the production of cement from the carbon dioxide (CO2) budget, North America at the beginning of the 21st century is a net sink for CO2, storing it at a rate between 1.7 to 2.9 billion tons (Gt) per year. These rates were estimated by King et al. (2012), who have recently provided a “synthesis of syntheses” from various prior studies. The size of this North American sink is modified largely by land-use change and natural disturbances. Currently, recovery from past forest harvest and reforestation of abandoned cropland in the US is the largest sink: it is responsible for 30-70% of the net North American sink (Mexican deforestation, in contrast, is a source of atmospheric CO2). Considering disturbances only, wildfires are the largest source of CO2, though other natural events, such as the mountain pine beetle outbreak in Canada, have had non-negligible impacts on the CO2 budget. The magnitude of the North American sink in the first decade of this century is equivalent to 26-44% of 2010 North American fossil fuel emissions (of which 85% come from the US), which would imply that it has played an important role in modifying the effect of fossil fuel combustion on global climate trends.
King, A. W., D. J. Hayes, D. N. Huntzinger, T. O. West, and W. M. Post. 2012. North American carbon dioxide sources and sinks: magnitude, attribution, and uncertainty. Frontiers and Ecology in the Environment Vol. 10, 512-519. doi: 10.1890/120066.

Wildlife Corridors and Climate Change in the Northwest

A study by Nuñez et al. (2013) explores the potential for maintaining wildlife corridors in the northwest given future climate change conditions. Corridors defined will allow migration along spatial temperature gradients, keeping similar habitat conditions and threading among human land-uses and barriers. Researchers used a coarse-scale analysis of current land-uses highlighting connectivity among low human influence areas coupled with maps of current temperature patterns and using a “cost-distance” algorithm to estimate potential wildlife movement.

The study assumes identified corridors are robust to uncertainty in climate change conditions because the focus on temperature gradients and land-use shows optimum routes for migration when climate actually does change. Additionally, the model used does not depend on individual wildlife habitat modeling but rather focuses only on temperature compatibility and potential for migration within suitable temperature ranges.

The study tends to focus on identifying large “natural” patch areas, and assumes species will migrate over extended periods of time (e.g., generations) allowing adjustments of entire habitats. Movement of wildlife is assumed to be from warmer to cooler or like conditions following unidirectional changes in temperature and avoiding extremes. Although the model simplifies temperature and land-use assumptions, it is flexible enough to incorporate new climate and land-use patterns, allowing application in other locations under different demographic conditions or as climate changes.
Nuñez, T. A., J. J. Lawler, B. H. Mcrae, D. J. Pierce, M. B. Krosby, D. M. Kavanagh, P. H. Singleton, and J. J. Tewksbury. 2013.  Connectivity Planning to Address Climate ChangeConservation Biology. doi: 10.1111/cobi.12014.

National Fish, Wildlife and Plants Climate Adaptation Strategy
The Climate CIRCulator is brought to you by The Pacific Northwest Climate Impacts Research Consortium (CIRC). CIRC delivers science, information, and tools to decision makers responsible for the management of  resources and services in a changing climate. Our team consists of experts from Oregon State University, the University of Oregon, the University of Idaho, Boise State University, and the University of Washington. CIRC is funded by the National Oceanic and Atmospheric Administration (NOAA) and housed in the Oregon Climate Change Research Institute (OCCRI) at Oregon State University. The OCCRI brochure can be downloaded  here.
The Climate CIRCulator, March, 2013, Issue 3.
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