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- CLIMATE
- PREDICTIONS
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BIOLOGYThe general biologic condition of the CPYRW was evaluated by the Ecosystems Investigations Program at the GSA. General ecosystem conditions, characterization of biological resources, habitat conditions, fish consumption advisories, and aquatic biodiversity is discussed in the Ecosystem Resources section of this report. The biological stream condition of the watershed has been determined by the Index of Biotic Integrity (IBI) method. Based on historical IBI collection data in the GSA database, biological condition was determined for 35 sites within the CPYRW by calculating the IBI using metrics and scoring criteria presented in O’Neil and Shepard (2012). Four sites rated very poor (12%), nine sites rated poor (26%), nine sites rated fair (26%), 11 sites rated good (30%), and two sites rated excellent (6%). Samples taken at these 35 sites represented a range of stream water quality and habitat conditions and were taken for different reasons in the CPYRW. The distribution of these sampling sites is shown in figure 6. Around one-third of the sites had poor to very poor biological condition while two-thirds of the sites were fair or better. The IBI varies seasonally reflecting natural fish community changes due to reproduction cycles, population recruitment and growth, and climate-related flood and drought cycles. As such, several samples should ideally be collected from different seasons to adequately characterize the statistical distribution of IBIs at any one site. SOILSThere are three soil orders in the CPYRW study area: Ultisols, Inceptisols and Histosols (fig. 7). Ultisols account for 90% of soil orders within the study area. Ultisols are intensely weathered soils of warm and humid climates. They are usually formed on older geologic formations in parent material that is already extensively weathered. They are generally low in natural fertility and high in soil acidity, but contain subsurface clay accumulations that give them a high nutrient retention capacity (University of Nebraska, USDA and National Science Foundation [or University of Nebraska and others], 2014). Ultisol soils can be agriculturally productive with the addition of lime and fertilizers. The Ultisol taxonomic soil classifications for the CPYRW include the following: Coarse-loamy, siliceous, subactive, thermic Plinthaquic Paleudults; Fine-loamy over sandy or sandy-skeletal, siliceous, semiactive, thermic Typi; Fine-loamy, kaolinitic, thermic Plinthic Kandiudults; Fine-loamy, kaolinitic, thermic Typic Kandiudults; Fine-loamy, kaolinitic, thermic Typic Kanhapludults; Fine-loamy, siliceous, semiactive, thermic Plinthaquic Paleudults; Fine, mixed, semiactive, thermic Typic Hapludults; Fine, smectitic, thermic Vertic Hapludults; and Loamy, kaolinitic, thermic Grossarenic Kandiudults (USDA, 2009). Inceptisols account for 6% of soil orders within the CPYRW area and are described as soils in the beginning stages of soil profile development. The differences between horizons are just beginning to appear in the form of color variation due to accumulations of small amounts of clay, salts, and organic material (University of Nebraska Library, 2014). The natural productivity of these soils varies widely and is dependent on clay and organic matter content as well as other plant-related factors. The Inceptisol taxonomic soil classification for this area is fine-loamy, siliceous, active, acid, thermic Aeric Endoaquepts (USDA, 2009). Histosols account for the remaining 4% of soil orders within the CPYRW. They are described as soils without permafrost predominantly composed of organic material in various stages of decomposition (University of Nebraska Library, 2014). They are usually saturated with water that creates anaerobic conditions and causes faster rates of decomposition, resulting in increased organic matter accumulation. They generally consist of at least half organic materials, which are layered and common in wetlands. The Histosol taxonomic soil classification for this area is Dysic, thermic Typic Haplosaprists (USDA, 2009). The taxonomic soil classification areas for the CPYRW are listed in table 5.
Since weather records at multiple stations became available in the 1880s, analyses of these data indicate that, overall, the climate of Alabama has changed little. The temperature of the state has declined slightly since 1883, especially in the climatically sensitive metric of summer daytime maximum temperatures (-0.16 °F per decade). A reconstruction of average daily maximum summertime temperatures near the CPYRW shows year-by-year variability since 1883 and general cooling (fig. 9) (Christy, 2014 [change to personal communication or unpublished data?]). As an illustration of this decline, since 1883, at least one station in Alabama reached 100°F or greater in every year to 1964. Since 1965, however, there have been six summers (1965, 1974, 1994, 2001, 2003 and 2013) without any station reaching 100°F despite the presence of many more stations. The downward temperature trend of the past 130 years cannot be used as a forecasting tool, however, and one would anticipate the very hot summers of the first half of the 20th century are likely to return simply from natural variability as well as from the added influence of extra greenhouse gases in the atmosphere (Christy, 2014). Figure 9 shows year by year average of daily maximum temperatures for June-August (1883-2013) for an area centered on Montgomery, Alabama, and extending 50 miles in all directions. Thirty-two climate stations were used in this analysis (Christy, 2014). An analysis of annual precipitation since 1895 (using the water-year of October through the following September) indicates variations around a humid climate. Figure 10 shows the water-year annual precipitation for Climate Division 7 (Alabama Coastal Plain) which includes the CPYRW region. There is no rising or falling trend of any significance in the observations. As with the nation as a whole, the occurrences of very dry and very wet periods have not changed over time (Christy, 2014). Because Alabama occupies the land between the warm waters of the Gulf of Mexico and is subject to continental influences to the north and west, extremes in weather events can have a large range, relative to other parts of the country. The extremes of these events, i.e., floods, droughts, heat waves, cold outbreaks, winter storms, severe thunderstorms, tornadoes, and tropical cyclones, often inflict considerable damage on infrastructure as well as nonhuman systems. These events have contributed to more billion-dollar weather disasters in the Southeast than in any other region of the USA during the past three decades, though when normalized for inflation and population growth, there is no long-term trend in these disasters (Pielke, 2013, Senate EPW Testimony and references therein). In other words, the evidence is very strong to demonstrate that extreme events themselves (hurricanes, tornadoes, winter storms, heat waves, cold spells, droughts, floods, etc.) are not increasing in frequency or intensity. However, the infrastructure exposed to such events has expanded significantly both in quantity and value so that damage now is more severe cost-wise than in the past.
The term “projection” describes how future climate is expected to respond to various scenarios of population growth, greenhouse gas emissions, land development patterns, and other factors that may affect climate change. The latest IPCC (AR5, 2013) uses what is termed “Representative Concentration Pathway” or “RCP” that becomes the input for climate model projections. These RCP scenarios attempt to account for changes in energy systems, population, etc., and are defined as (basically) the maximum radiative forcing that the extra greenhouse gases will exert on the climate system (Christy, 2014). The values range from 2.6 Wm-2 to 8.5 Wm-2 (fig. 11). By comparison, the earth, on average, absorbs the sun’s energy at a rate of about 235 Wm-2. The basic idea is that with greater forcing, greater changes should be observed (Christy, 2014). The change we can be most confident of, related to the climate system, will be the continued rise in sea level (Christy, 2014). Between 15,000 and 7,000 years ago the melting of the major ice sheets on the continents that had formed during the last Ice Age (120,000 to 20,000 years ago) caused sea level to rise at a rate of 5 inches per decade—a total of over 300 ft. The recently revealed submerged “forest” off Mobile Bay, found in 60 ft of water, grew on dry ground 12,000 years ago, before the sea rose to drown it (Christy, 2014). The previous warm period, or interglacial (130,000 years ago), saw sea levels about 20 ft higher than at present, so the natural direction of sea level is to continue rising as there is still land-bound ice to melt (Christy, 2014). Over the past 7,000 years, sea level rose more slowly as the remaining land ice, vulnerable to melting, was limited and resided in mountain glaciers and the ice caps of Greenland and Antarctica. General cooling of the Earth occurred from 5,000 years ago to about 1850 during which glaciers advanced, such as those in the Rocky Mountains, to their largest extent in the past 10,000 years (Christy, 2014). Since 1850, glaciers have been in general retreat, and along with some melting from Greenland, has added about 0.7 inch per decade of sea level rise. The oceans have warmed since 1850 as well, and this expansion has added another 0.3 to 0.6 inch per decade (Christy, 2014). The total global average rate of sea level rise in the past century has not accelerated and is currently estimated at 1.2 inches per decade (IPCC WG1 Fig. 3.4). Estimates of total rise by the end of the 21st century are plagued by considerable uncertainty and depend on such processes as local land motion, and range from 8 to 24 inches (IPCC WG1 Fig. TS.21). Mean relative sea level rise across the northern Gulf coast is generally consistent with the global trend, except in regions of considerable land subsidence or where land sediments have been prevented from replenishing delta areas (Christy, 2014). Other than sea level, very little confidence can be attached to regional projections of climate change in terms of the features of weather and climate that are important (Christy, 2014). For example, figure 12 displays 76 climate model runs of Alabama summer temperature and precipitation beginning in 1895 and ending in 2013. Summer is the season in which changes are more clearly seen relative to the background variability. (Note that though these projections are labeled “RCP8.5” scenario, there is virtually no difference between the various RCP scenarios, since the time period below is primarily concerned with the known past, or historical forcings which were identical in all RCP scenarios.) In this period, for which we have observations, the models universally and significantly over estimated temperature change (as noted above, it actually declined in Alabama) and were highly inconsistent in terms of precipitation (90% were too dry) (Christy, 2014). Regarding the future of Alabama climate, figure 13 shows projections for precipitation from scenario RCP4.5 (a middle scenario) for the southern half of the state that includes the CPYRW during the critical growing season (March through August). No actionable information is provided from these latest model projections. On average, the models depict no change in growing season rainfall (Christy, 2014). In consideration of the evidence above, it is clear that the observational record can provide useful information for the future (Christy, 2014). Observations indicate that extremely dry/wet and cold/hot periods will continue to occur. Anticipating and adapting to the impacts of these past extremes given today’s population, infrastructure and resource needs is a prudent exercise to consider. For example, a heavy rainfall event with today’s infrastructure which includes large areas of impervious surfaces, will likely cause greater flood damage than would otherwise be the case. Further, several cold and icy events have occurred in the past 20 years that have exposed Alabamian’s inability to cope with such events with the present modern infrastructure (Christy, 2014).
Projected climate changes will stress human health. Heat waves caused by frequently high temperatures will likely increase heat stress and heat-related deaths. Since high temperatures correlate with poor air quality, there will most likely be an increase in respiratory illnesses (USEPA, 2014d). Impacts from reduced air quality include increases in ozone as well as changes in fine particulate matter and allergens. The spread of certain types of diseases are linked with warmer temperatures, flooding, and increases in geographic range that were limited by temperature. Climate is an important environmental influence on ecosystems. For many species, climate influences where they live as well as key stages of their life cycle, such as migration, blooming, and mating. Climate impacts on ecosystems include changes in timing of seasonal life-cycle events, range shifts, food web distributions, threshold effects, the spread of pathogens, parasites, and disease, and extinction risks (USEPA, 2014d). Other effects from warmer temperatures include an increase in the occurrence of wildfires as well as pest outbreaks. Climate-related stressors that threaten wildlife will also affect domestic animals. Livestock may be at risk, both directly from heat stress and indirectly from reduced quality of their food supply. Fisheries will be affected by changes in water temperature that shift species ranges, make waters more hospitable to invasive species, and change life cycle timing (USEPA, 2014d). Agriculture is highly dependent on specific climate conditions. Moderate warming and more carbon dioxide in the atmosphere may help plants to grow faster. However, more severe warming, floods, and drought may reduce yields. Declining soil moisture and water scarcity will likely stress agricultural crops. These climate-induced stressors may ultimately affect human food supply, especially in areas with significant population growth. RECOMMENDATIONSPreparation for potential climate change impacts includes monitoring climate conditions (short and long term) and corresponding water resource availability and water use, precipitation and temperature, surface-water discharge, and groundwater levels. CPYRWMA flood warning system and levees at Elba and Geneva must be properly maintained in perpetuity. Coordination and participation with state drought committees, ADECA OWR, Alabama Department of Agriculture and Industries (ADAI), Alabama Emergency Management Agency (AEMA), USDA Natural Resources Conservation Service (NRCS), U.S. Army Corps of Engineers (USACE), and local governments and water supply systems. Close coordination with stakeholders particularly susceptible to climate impacts such as farmers and public water suppliers should be maintained to share information and remedial strategies. POLICY OPTIONSPublic water suppliers should develop enforceable water conservation policies. A state-implemented water management plan and associated regulations should be developed for equitable water resource distribution and conservation. DROUGHTIn the past, drought conditions have endangered Alabama’s water resources and adversely affected the livelihood of many people. Drought is a natural event, but can be exacerbated by climatic conditions. There are several different indicators of drought: precipitation, soil moisture, forestry fire conditions, stream flows, groundwater levels, and reservoir elevations (Littlepage, 2013). The impacts of drought fall under five main categories: agriculture, industry, domestic supply, recreation, and environment. Each of these drought impact categories have inherent economic risks including crop failure, increased need for irrigation, additional resources to maintain livestock health, timber loss from wildfires, hydroelectric power failure, impaired waterway navigation, and increased food costs (National Drought Mitigation Center (NDMC), 2014). As water becomes scarce, the environment becomes vulnerable to drought impacts including loss of habitat, lack of water and food sources for wildlife, increased disease, migration of wildlife, additional stress on threatened and endangered species, loss of wetlands, wind and water erosion of soils, poor soil quality, threat of aquifer depletion, and lower water levels in water bodies (NDMC, 2014). Human health and social wellbeing are reliant upon environmental health. When environments are compromised, social impacts follow. These impacts include health problems related to low water flows, dust, and poor water quality, increased threat to public safety, reduced incomes, fewer recreational activities, and loss of human life (NDMC, 2014). As demonstrated by the potential drought impacts listed above, water resource scarcity compromises the quality of life for present and future generations. It is important to implement mitigation strategies, identify future water sources, and practice water conservation to protect natural resources. In May 2002, the Alabama Department of Economic Affairs Office of Water Resources was given the initial Executive Order (EO #70) to establish organizations and processes for drought planning. In order to develop a statewide drought management plan and coordinate drought response, ADECA OWR established these organizations: Alabama Drought Assessment and Planning Team (ADAPT) and the Monitoring and Impact Group (MIG). ADAPT coordinates intergovernmental drought response, management, and appropriate media information releases. They also monitor drought-related activities and advise the Governor and ADECA OWR, in coordination with input from the MIG (ADECA OWR, 2012b). The MIG is responsible for monitoring and analyzing all available climate and hydrological data to assess current drought conditions within the state. Based on these analyses, the MIG recommends levels of conservation implementation, which is reported to the ADECA OWR and the ADAPT (ADECA OWR, 2012b). The Alabama Drought Management Plan was released in 2004 to establish a framework for the assessment of drought conditions, assist stakeholders and water managers in mitigating drought conditions, and encourage water conservation practices (ADECA OWR, 2012b). The plan also establishes an organizational structure to facilitate exchange of data in addition to interagency coordination. In order to accomplish these goals, the plan (1). defines a process to address drought and drought-related activities, such as monitoring, vulnerability assessment, mitigation, and impact assessment and response, (2) identifies long- and short-term activities that can be implemented to reduce and prevent drought impacts, (3) identifies local, state, federal, and private sector entities that are involved with state drought management and defines their responsibilities, and (4) acts as a catalyst for creation and implementation of local drought and response efforts (ADECA OWR, 2012b). On June 24, 2011, Governor Robert Bentley issued Executive Order 19 on Drought Planning and Management, which enhanced drought planning efforts on a state level and streamlined organizational structure. It formally tasked the ADECA OWR to support Alabama’s drought planning and response efforts. The 2007 drought was the first time the Alabama Drought Plan was activated in actual drought conditions. Coordination and communication worked well among government agencies and reservoir systems. A process was developed for Alabama to be entered into the national drought monitor map (U.S. Drought Monitor). Adjustments were made to the drought plan concerning drought regions, drought indicators, and the need for local and timely impact data (Littlepage, 2013). The ADECA OWR periodically revises the Drought Declarations based on current and projected conditions. The latest drought declaration was issued on February 28, 2013, stating that recent rains had continued to improve drought conditions in the state, but emphasizing that public and private water users should continue to monitor water conditions. The CPYRW is included in regions 6, 7, and 8 of the Alabama Drought Management Plan (fig. 14). Available drought related data are provided by the agencies listed in table 8. On January 14, 2014, the Alabama Drought Planning and Response Act (No. 2014-400, HB49) was codified by the Alabama Legislature to create the Alabama Drought Assessment and Planning Team (ADAPT) and to provide advice to the Office of Water Resources on development of a statewide drought plan, assess drought conditions in the state, advise the Governor when a drought emergency exists, and recommend mandatory water restrictions to the Governor. The ADAPT consists of various state agencies including the Choctawhatchee, Pea, and Yellow Rivers Management Authority. An amendment was later added which authorizes the Governor to invite representatives of county government to serve on the team in a nonvoting capacity. The Alabama Drought Planning and Response Act is included in Appendix _. There is no way to prevent drought; however, the effects of drought can be reduced or eliminated altogether. The impact of drought can be reduced by improving overall forest health (which reduces the risk of drought induced fires), by improving and maintaining water systems which reduces pumping failures, and by establishing and implementing contingency plans, such as predetermined water conservation measures or by designating alternative emergency water sources (ADECA OWR, 2012b). The Alabama Drought Management Plan includes domestic, agriculture, environmental, industrial, and recreation drought response sectors to be used in coordination with local drought ordinances. Domestic and residential water suppliers are encouraged to develop local water conservation plans and ordinances to promote reductions in water use during drought conditions or implement more severe restrictions, if necessary (ADECA OWR, 2004). The development of additional water sources may be a viable option to maintain public water supply where there is water scarcity; this is discussed specifically for the CPYRW study area in the Identification of Future Water Sources section. Water conservation and water reuse are discussed in detail in the Water Source Sustainability section. Years of prevalent drought within the CPYRW area during the past decade are mentioned in the Precipitation Monitoring section of Water Monitoring. Research including drought indices and drought impacts, shown on hydrographs, are discussed in detail in the Drought Impact section of Water Quantity. 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