Climate Change in Africa: Impacts and Effects on the Inhabitants of the Lake Chad Region.
The Department of Energy and Climate Change defined climate as the average weather experienced over a long period. This includes temperature, wind and rainfall patterns. The climate of the Earth is not static, and has changed many times in response to a variety of natural causes. Due to human activities in emmiting green house gases has resulted the Earth to get warmed by 0.74°C over the last hundred years. Around 0.4°C of this warming has occurred since the 1970s. Climate is now one of the major phenomenon threatening lives and humanity in general since the beginning of industrial revolution. Climate exerts a profound influence on the lives of poor populations in the Lake Chad region of Africa who depend on fishing and crop cultivation for livelihood and sustenance, who are unprotected against climate-related diseases, who lacked secure access to water and food and who are vulnerable to hydro meteorological hazard. The effects of climate change on the study area are many and include diminishing resources and conflicts over the available limited water resources. The Lake Chad region is a fragile area with high climate variability and extremes of weather. As this inland water is used for domestic and agricultural purposes, salt mining, as well as transportation by Nigerians, Nigeriens, Chadian and Cameroonians, it is an area of trans-boundary water conflicts. This paper examines the part played by climate change in the decline of fishery resources and livelihood activities in the Lake Chad region. Data from field studies, structured interview and secondary sources show that fish catches and livelihood activities have declined tremendously in recent times due to several factors including overexploitation and increasing demands on the aquatic resources. Findings from the study show that droughty periods have resulted in the reduction of open lake water surface from about 25,000 km2 in 1973 to less than 2,000 km2 in the 1990s. This has led to the diminishing aquatic and other resources in the area as well as potentially major challenge to social and economic development of the region. Although the importance of fisheries and irrigation in the region are well known, mechanism for mitigating and/or responding to climate change is not in place. A call is made in this paper to support the earlier advocate by scholars for inter-basin water transfer from the Congo Basin to the Chad Basin and the construction of canals on the Lake Chad to boost fishing activities and transportation.
Simulation of Climate Change Impacts on North American Lake-Ice Phenology and Composition
The formation and breakup of ice are important seasonal events in mid- to high-latitude lakes. The timing of these events, ice phenology, and the ice cover composition are sensitive to the characteristics of individual water bodies and to broader-scale weather patterns and climate variability. This study demonstrate that climate change in the form of global warming and increased precipitation has the potential to change ice cover duration and composition over high latitude lakes using the one dimensional processes based Lake thermo- and phytoplankton dynamics model (MyLake) with daily gridded data of atmospheric variables derived from the Canadian Regional Climate Model (CRCM4.2 - A2) over the cold regions of North America. Analysis of the simulation results for the baseline (1961 - 1990) and future (2041 -2070) time periods shows a reduction of lake ice thickness and ice-cover duration as a result of later freez-up and earlier break-up of lake ice. The study also reveals spatially dependant increase or decrease in snow-ice formation corresponding to the future climate scenario and the magnitude of precipitation and altitudes are found to have a more significant influence on lake-ice composition than the latitudinal effects.
Predicted Hydrological Impacts of Climate Change for Harp Lake and Catchment, South- Central Ontario
Potential hydrological impacts of two climate change scenarios were analyzed for a typical inland lake (Harp Lake) and its catchment in the boreal ecozone of Ontario, Canada. The first scenario was created by extrapolation of long-term trends of monthly temperature and precipitation over a 129-year data record, into a future target year 2050. This scenario predicts a slight temperature increase (0.6 0C per 50 years on average) in each of 12 months and a slight increase in monthly precipitation (on average 2.8 mm/m per 50 years). The second scenario was based on a Canadian general circulation model (GCM) prediction, which predicts larger changes and more differences among months. It predicts that the temperature of each month would increase in 2050 by 3.1 0C on average, and monthly precipitation would increase or decrease depending on the month by 1.7 mm/m on average compared to the present. The hydrological responses of the catchment and the lake were calculated using a USGS catchment water balance model and a proposed lake water balance model respectively, and the two models were calibrated with 26-years of hydrological and meteorological data from the Harp catchment. The USGS model has six parameters which were calibrated. Model-estimated runoff and observed runoff have a high correlation coefficient of 0.88. The model was then used to calculate catchment's responses in evapotranspiration and runoff under each of the two climate change scenarios. The lake's water balance model includes a relationship of lake outflow and inflow (i.e. catchment runoff) which was regressed using the 26-year data for each month, and a monthly water budget accounting. The change of lake-water level within a month was calculated as the difference of input term (precipitation, inflow) and output term (outflow, evaporation). The first scenario with a warmer and wetter climate predicted a smaller magnitude of hydrological impact than the second scenario. The first scenario showed an increase in evaporation each month, an increase in catchment runoff in summer, fall and winter, but a decrease of runoff in spring. The sum of these effects produced a slight rise in lake level. Annually, the runoff and lake level would increase by 18 mm and 0.01 m respectively, because the change in precipitation (34 mm) would exceed the change in evaporation (17 mm). In contrast, the second scenario with a warmer, drier climate predicted a greater impact, and indicated that evaporation would increase each month, runoff would increase in many months, but decrease in spring. Annual runoff and lake level would decrease by 57 mm and 0.02 m respectively, because the change in evaporation (90 mm) would exceed the change in precipitation (21 mm). In both scenarios the predicted water balance changes in winter and spring are pronounced. However, the two scenarios produce qualitatively different impacts on hydrology of the lake and its catchment.
Lacustrine Records of Forest Fire Indicators and Trace Elements Deposition in an Land Use Change Region in the Brazilian Amazonia (Alta Floresta, MT)
The dynamics of terrestrial ecosystems depend on interactions between the carbon cycle, nutrient cycles, and the hydrological cycle, all of which may be modified by climate and human actions. Terrestrial ecological systems, in which carbon is retained in live biomass, decomposing organic matter, and soil, play an important role in the global carbon cycle. Human activities change carbon stocks in these pools and exchanges between them and the atmosphere through land-use change and other activities. From 1850 to 1998 about 136 (+55) Gt C has been emitted as a result of land-use change, predominantly from forest ecosystems. Amazonia's carbon storage potential gives great importance to land-use changes in this region because disturbances of the natural landscape can increase atmospheric carbon and affect global biogeochemical cycles. Mercury release from gold mining activities and deforestation are the two most important environmental issues in the Amazon Basin. Gold mining activities in Amazonia have been responsible for the release of about 2000-3000 t of Hg over the last 20 y. In Alta Floresta region (southern Amazonia), concurrent with the deforestation, an intense gold rush occurred with the exploration of riverbed sediments. This region was a significant gold mining site from 1980 to 1996. This study aims to understand the atmospheric deposition rates of charcoal particles, mercury and other trace elements and discuss the environmental changes caused by man activities in an area of an intense land use change. Accordingly to the fact that in Brazilian Amazonia the colonization process generally takes place after the building of a road, an 82 cm core (AF SSW 150) was collected in a lake formed by the barrier effect of a road embankment and distant 150 km of the center of Alta Floresta city. The ages of the sedimentary sections in the core were calculated by the activity of 210Pb. The grain size profile showed a huge change from 1985, with the dominance of fine material. Before 1985, the coarse fractions prevailed. The counting of charcoal particles was done in microscopic laminas. Charcoal particles were present along the entire lacustrine faces of the core, but the greater concentrations were found in the top of the core, from 1980 to 2000, with the greatest peak in 1985. The percentual of organic carbon showed the same behavior of the charcoal, indicating that the greater fraction of the organic carbon in this sediment is from allochthonous material. The concentrations of Hg and other major and trace elements (Al, As, Co, Cr, Ti, V, Zn) also increased significantly from 1985. The AF SSW 150 core shows that the charcoal, Hg and other trace elements deposition are related to the land use change and gold mining. Trace elements and charcoal fluxes presented low values at the beginning of the human occupation (prior to 1980). At the beginning of the 1980s, there was an increase in the forest fires and mining activities. From 2000 to 2005 all the elements analyzed showed a decreased in their concentrations.
Patterns in change factors for assessing future climate change scenarios
New York City Department of Environmental Protection (NYCDEP) is undertaking a program to evaluate the potential effects of climate change on the New York City water supply. Preliminary simulations used a simple change factor methodology (CFM) to predict future climate conditions. In CFM, future changes in climate projected by General Circulation Models (GCMs) are applied to baseline climatology assuming that the difference between future and current GCM results are representative of the difference between future and current local climates, regardless of model biases in the current climate simulations. There are a number of different ways by which change factors have been estimated. The purpose of this presentation is to define a criteria for applying CFM based on a comparison of the statistical distributions of current and future GCM scenarios. The mathematical formulation of change factors varies with the statistical characteristics of the meteorological variable of interest. Analysis of statistical distributions provides an objective method for applying CFM across meteorological variables with inherently different levels of variability.