Environmental Challenges: Climate Change, Pollution, and Biodiversity Loss
Environmental Policy and Global Challenges
Priority Areas:
- Climate change
- Nature and biodiversity
- Natural resources and waste
- Environmental health and quality of life
Global Megatrends:
- Increasing global divergence in population trends: aging, growing, and migrating populations
- Urbanization: spreading cities and spiraling consumption
- Changing patterns of global disease burdens and the risk of new pandemics
- Continued economic growth
- Global power shifts: from a uni-polar to a multi-polar world
- Intensified global competition for resources
- Decreasing stocks of natural resources
- Increasing severity of the consequences of climate change
- Increasingly unsustainable environmental pollution load
Major Global Environmental Problems
Climate Change
(Deglaciation of the West Antarctic ice sheet (WAIS) and Greenland ice sheet (GIS)): Due to the combustion of fossil fuels, the concentration of carbon dioxide and other greenhouse gases in the atmosphere has been increasing. In the last few decades, the presence of these gases in the atmosphere has accumulated steadily, resulting in an enhanced greenhouse effect. Solar radiation strikes the Earth. Some of it is reflected back by the atmosphere into space, and some passes through the atmosphere to Earth.
Greenhouse Gases:
- CO2: Burning fossil fuels, deforestation
- CFCs: Refrigeration, solvents, insulation foams
- CH4: Termites, burning of fossil fuel, wood, landfills
- N2O: Burning of fossil fuels, fertilizers
Temperature Rise:
The world’s average surface temperature has increased by around 0.6 degrees Celsius over the last 100 years. Melting of polar ice caps, changes in rainfall patterns, and an increase in the frequency of hurricanes and storms are a few of the adverse effects of climate change. The average global temperature could increase between 1.4 and 6 degrees Celsius in the 21st century.
Tipping Points:
If a system has more than one equilibrium state, transitions to different states are possible. If a tipping point is passed, the development of the system is no longer determined by the timescale of the pressure but rather its internal dynamics, which can be much more rapid than the original pressure.
Ozone Layer Depletion
Ozone (O3) is a highly reactive molecule with three oxygen atoms. The stratosphere contains a thin layer of ozone. This ozone layer serves as a natural filter for blocking damaging incoming UV radiation from the sun. The UV-C (wavelength lesser than 280 nm) is most damaging to biological systems. The thinning of the stratospheric ozone layer is termed the “ozone hole.”
Causes of Ozone Layer Depletion:
Natural Causes:
A number of natural substances destroy stratospheric ozone: Hydrogen oxide (HOx), Methane (CH4), Hydrogen gas (H2), Nitrogen oxides (NOx). Chlorine monoxide (ClO) may be released during volcanic eruptions. Tiny particle matter in the stratosphere, stratospheric aerosols, may also lead to ozone destruction.
Human Activity:
The most damaging agents are human-made CFCs, widely used as refrigerants and to pressurize spray cans. In the stratosphere, chlorine atoms from CFCs react with ozone to form chlorine monoxide and an oxygen molecule. Ozone is naturally produced and destroyed, leading to a balance. If ozone production and destruction are balanced, ozone levels remain stable.
Large increases in stratospheric ODS, however, have upset that balance. In effect, they are removing ozone faster than natural ozone creation reactions can keep up.
Effects:
- On human beings: Increase susceptibility to skin cancer, damage DNA and cornea, increase cataracts.
- Harmful effects on plants: Inhibit photosynthesis, repress metabolism and growth, destroy cells.
- On other organisms: Marine/freshwater organisms are very sensitive to UV rays; plankton populations are severely damaged.
- On non-living materials: Accelerate the breakdown of paints and plastics, affect gradient temperature gradient levels in the atmosphere.
Biodiversity
What is Biodiversity: The richness of life on Earth, millions of plants, animals, microorganisms (including the genes they contain), and complex ecosystems which form the environment.
Biodiversity can be classified as:
- Species biodiversity: It includes a total number of different taxonomic or biological species.
- Genetic biodiversity: It includes land traces; horticultural varieties; cultivars.
- Ecosystem biodiversity: It includes various biological zones, like lakes, deserts, coasts, estuaries, wetlands, mangroves, coral reefs, etc.
Both flora and fauna all over the world are under assault from a variety of indiscriminate human activities. These activities are often related to the rapid growth of the human population, deforestation, urbanization, and industrialization.
Reasons for Loss of Biodiversity:
- Loss of habitat: Due to the demands of a growing human population, wetlands are being made dry through landfills, and natural forests are cleared for industry, agriculture, dams, etc. Thus, plant and animal species are temporarily or permanently affected.
- Pollution: Alters the habitat to such an extent that it becomes critical for the survival of some species.
- Overuse: Whales for oil, fish for food, trees for wood, plants for medicines, etc., are being removed by humans at higher rates than they can be replaced.
- Introduction of foreign species: Into new habitat areas is increasing, with new species sometimes thriving at the expense of native species.
Ocean Exhaustion
The ocean provides our largest source of oxygen and protein and absorbs around a quarter of our carbon dioxide emissions.
- One of the biggest threats to our oceans is man-made pollution. Discarded plastics and other residential waste, discharge from pesticides, and industrial chemicals eventually find their way into the sea with devastating consequences for marine life and the habitats they depend on.
- It is estimated that 80% of marine pollution originates on land. Land-based pollutants are contributing to ocean ‘dead zones.’
- Plastics are one of the biggest man-made pollutants in the marine environment, with an estimated eight million tonnes of plastic waste finding its way into our oceans each year.
Pollution
- Pollution of air, water, and soil requires millions of years to recoup.
- Industry and motor vehicle exhaust are the number one pollutants.
- Heavy metals, nitrates, and plastic are the main toxins responsible for pollution.
- Water pollution is caused by oil spills, acid rain, and urban runoff.
- Air pollution is caused by various gases and toxins released by industries and factories and the combustion of fossil fuels; soil pollution is majorly caused by industrial waste that deprives soil of essential nutrients.
Water Pollution
Water pollution occurs when harmful substances—often chemicals or microorganisms—contaminate a stream, river, lake, ocean, aquifer, or other body of water, degrading water quality and rendering it toxic to humans or the environment.
Causes of Water Pollution:
Water is vulnerable to pollution. Known as a “universal solvent,” water can dissolve more substances than any other liquid on Earth.
Groundwater:
When rain falls and seeps deep into the earth through cracks and porous spaces of an aquifer (basically an underground storehouse of water), it becomes groundwater—one of our least visible but most important natural resources. Groundwater gets polluted when contaminants—from pesticides and fertilizers to waste leachate from landfills and septic systems—make their way into an aquifer, rendering it unsafe for human use. The quality of fresh water is influenced by land use and vegetation cover.
Surface Water:
Covers about 70 percent of the Earth’s surface. Freshwater quality is worsening due to nutrient pollution, which includes nitrates and phosphates. Municipal and industrial waste discharges contribute toxins as well. The agricultural sector is the biggest consumer of global freshwater resources, with farming and livestock production using about 70 percent of the earth’s surface water supplies, and it’s also a serious water polluter. FAO estimates that over the next 30 years, water consumption in agriculture will increase by 14%.
Acid Rain:
Refers to any precipitation that is more acidic than normal. Acid rain is caused by atmospheric pollution from acidic gases such as sulfur dioxide and oxides of nitrogen emitted from the burning of fossil fuels.
Effects:
- On aquatic life: The pH of the surroundings is important for the metabolic processes of aquatic organisms. Acid rain kills the gametes, affecting the life cycles and productivity. This affects aquatic food chains in acidic water bodies, causing severe ecosystem imbalances.
- On terrestrial life: Acid rain damages cuticles of plant leaves, resulting in etiolation of foliage. This, in turn, reduces photosynthesis. Reduced photosynthesis accompanied by leaf fall reduces plant and crop productivity.
- On forests: Acid rains damage forests and kill vegetation and cause severe damage to the landscape.
Air Pollution
Air pollution is a mix of particles and gases that can reach harmful concentrations both outside and indoors. Its effects can range from higher disease risks to rising temperatures. Carbon dioxide is considered to be an air and greenhouse pollutant when associated with cars, planes, power plants, and other human activities that involve the burning of fossil fuels such as gasoline and natural gas. Sulfur dioxide is a component of smog and a cause of acid rain.
Causes of Air Pollution:
- Natural sources: Volcanic eruptions, forest fires, pollen grains of flowers.
- Man-made sources: Deforestation, emissions from vehicles, wars.
Soil Pollution
Soil pollution causes contamination of soil and degrades the soil quality. Soil contamination or soil pollution can occur either because of human activities or because of natural processes. Soil contamination can occur due to the presence of chemicals such as pesticides, herbicides, ammonia, lead, nitrate, mercury…in an excess amount.
Pesticides:
Were used for pest control in agriculture for killing rodents, weeds, insects, etc., and avoiding the damages due to these pests. They are insoluble in water and non-biodegradable, thus accumulating in the soil.
Herbicides:
Like sodium arsenite (Na3AsO3), sodium chlorate (NaClO3) can decompose in a few months. They affect the environment. Even though they are not as harmful as organo-chlorides, most herbicides are toxic. They are known to cause birth defects.
Land Cover and Land Use Change
- Humans affect climate through changes in land use and land cover.
- Cities are warmer than the surrounding countryside because the greater extent of paved areas in cities affects how water and energy are exchanged between the land and the atmosphere.
- Expansion and intensification of human land use causes major changes in biodiversity around the world. Land use change will likely have the largest effect on terrestrial ecosystems in the coming century.
- Changes in land cover and land use influence biodiversity by altering habitat, ecological processes, and biotic interactions.
- The most obvious repercussions of land use change are loss, fragmentation, and degradation of habitat.
Desertification
Desertification is the destruction of the biological potential of the land, which ultimately leads to the formation of a desert.
Causes:
- Over cultivation
- Overgrazing
- Deforestation
- Salt accumulation due to irrigation
Over Cultivation:
Every cycle of cultivation is preceded by plowing to remove weeds. The plowed land turns soil upside down, thus exposing rich subsoil to wind and water erosion, primarily on slopes.
Overgrazing:
Deserts receive less rainfall and have sparse vegetation – grasses and herbs best used for grazing.
Deforestation:
Forests and vegetation prevent soil erosion and hold water in the soil. Plant roots absorb and recycle nutrients released from the decaying organic matter.
Salting due to Irrigation:
Demand for agricultural land leads to crops grown in areas with little access to natural water. Water is supplied by artificial means and irrigation methods. Irrigation water often contains Water used for irrigation is lost from agriculture field through evaporation and transpiration by crop plants.
Hazardous Waste:
Any substance released into the environment causing substantial damage to public health and the environment due to:
- Toxicity
- Ignitability
- Corrosivity
- Reactivity
Farming Impacts:
Agriculture is responsible for about 80% of deforestation worldwide. The yield of existing farmland can be increased through intensive farming to feed our rapidly growing population. This approach is characterized by reliance on mechanization, pesticides, and chemical fertilizers. Such practices can be associated with soil erosion or depletion. Deforestation, in turn, leads to a reduced ability to capture CO2, thus exasperating the greenhouse gas problem.
Eutrophication
Agricultural runoff is one of the main causes of eutrophication, the presence of excessive nutrients in bodies of water, such as large pockets. There are more than 400 marine ‘dead zones’ caused by eutrophication. Eutrophication causes the dense growth of plant life that consumes oxygen, resulting in the death of aquatic animals. Other major sources of eutrophication are industry and sewage disposal–both related to population growth. The cost of mediating eutrophication in the U.S. is over $2.2 billion annually.