Climate change and chemicals : Environmental and biological aspects

Our climate is changing. these changes are due to two main reasons. The first and foremost is due to emissions of green house gases (GHGs) to atmosphere. The principal GHGs are carbon dioxide, methane and nitrous oxide. Human activities such as burning of fossil fuels, and agricultural activities (growing rice, application of nitrogen fertilisers, livestock rearing) have increased the amount of GHGs in the atmosphere in recent times. The enhanced greenhouse effect (an increase in the concentrations of GHGs) has resulted in a change in weather and climate of our planet. Some of these effects are rising of surface and ocean temperatures, rising of sea levels, widespread melting of glaciers and snows, rising of atmospheric CO2 concentrations and extreme weather events (intense drought, intense precipitation, heat waves). The likely negative impacts of climate change or CHG effects are acidification of oceans, changes in river hydrology, changes in abundance and distribution of biodiversity, coral bleaching, increased incidence of pests and diseases (malaria, dengue), harmful algal blooms and increase in the toxicity of common harmful pollutants and more heat waves, etc. Despite several negative impacts, there are a few beneficial aspects of enhanced GHGs effects, for example, higher atmospheric concentrations of CO2 (or carbon dioxide fertilisation) may enhance the productivity of seagrasses, mangroves and crop production including rice, wheat, soybeans (so called C3 crops). Higher temperatures may accelerate the growth of temperate fish. Part 1 of the book (chapter 1-5) provides an introduction to GHGs and its relationships with climate change and likely impacts of climate change on freshwater resources, agriculture and livestock, fisheries and aquatic ecosystems and human health.