HTH Chapter 21

population growth

• the united nations projects that the world population will grow to 9.8 billion people by 2050, given recent jumps in fertility rates.

• other factors including overall survival and life expectancy at birth may contribute to over 12 billion by 2100.

global population growth

• 50 percent of global population growth by 2050 will occur in 9 countries: India, Nigeria, the Democratic Republic of the Congo, Pakistan, Ethiopia, the United Republic of Tanzania, the US, Uganda, and Indonesia.

educated women and fertility rates

• in countries where women have little education and little control over reproductive choices, and where birth control is not easily available, pregnancy rates continue to rise.

• as women become more educated, obtain higher socioeconomic status, work more outside the home, and have more control over reproduction, and birth control becomes more accessible, fertility rates decline.

zero population growth

• proponents of zero population growth believe that each couple should produce only two offspring, allowing the population to stabilize.

decreased mortality

• mortality rates from chronic and infectious diseases have declined as a result of improved public health infrastructure, increased availability of drugs and vaccines, and better disaster preparedness. 

• as people live longer, they add more years of resource consumption and add to the overall human footprint on the environment. 

differing growth rates

• China and India are the most populous countries, making up 37 percent of the world population

  • China has 1.4 billion people

  • India has 1.3 billion people

• the US has 326 million people and a net gain of one person every 8 seconds, and is among the fastest growing industrialized nations, also with one of the largest ecological footprints. 

• of the ten largest nations, Nigeria is growing the fastest.

analyzing the carrying capacity of Earth

• since 1996, the global demand for natural resources has doubled.

• it now takes 1.5 years to regenerate the renewable resources humans use in 1 year.

• we are running out of the natural resources necessary to sustain us, and the problem is growing at an unprecedented rate.

• when essential resources become unavailable, the likelihood of human conflict to ensure survival will increase, along with increased pressure on all living things.

effects of unchecked human population growth

• impact on ecosystem

• impact on other species 

• impact on the food supply

• land degradation and contamination of drinking water

• energy consumption

human pop growth impact on ecosystems

• aquatic ecosystems are heavily contaminated by chemical and human waste, particularly by fossil fuels.

• at least 25 percent of the excess carbon dioxide released into the atmosphere dissolves in the water, at a rate of nearly 22 million tons per day. 

• carbon dioxide causes the ocean’s pH to become more acidic leading to ocean acidification. 

• ocean acidification has devasting impacts on aquatic life creating dead zones that contain no life, and decreases biodiversity. 

human pop growth impact on other species

• changes in the ecosystem are resulting in the mass destruction of many species and their habitats.

• over 477 vertebrate species have gone extinct since 1900. vertebrates are declining at rates over 100 million faster than normal rates of extinction, leading to the sixth mass extinction of living creatures.

human pop growth impact on the food supply

• globally, oceans are being fished at rates 250 percent faster than they can regenerate. 

• scientists project a global collapse of all fish species by 2050 and major food shortages. 

human pop growth land degradation and contamination of drinking water

• the per capita availability of freshwater is declining rapidly.

• contaminated water remains the greatest single environmental cause of human illness.

• unsustainable land use and climate change are intensifying land degradation.

• fracking and other processes place additional pressure on increasingly scarce ground and surface water reserves.

human growth pop and energy consumption

• on the basis of total population, the US is the largest consumer of liquid fossil fuels and natural gas and is among the top four consumers of nuclear power, coal, and hydroelectric power. 

• in many developing regions of the world, movement toward greater industrialization and increasing citizen affluence have resulted in skyrocketing demands for limited fossil fuels. 

anthropogenic air pollutants (caused by humans)

• air pollutants caused by humans, including:

  • stationary sources: power plants, factories, and refineries.

  • mobile sources:

    • on-road vehicles

    • off-road sources, construction equipment

    • nonroad sources: planes, trains, watercrafts

Clean Air Act 1970

• passed by Congress and amended several times since 1970, it established standards for six of the most widespread air pollutants that seriously affect health.

  • sulfur dioxide, particulates, carbon monoxide, nitrogen dioxide, ground-level ozone, and lead. 

pollutant: carbon monoxide (CO)

• sources: motor vehicle exhaust, kerosene and wood burning stoves.

• health effects: headaches, physical and mental impairment, cardiovascular diseases, death.

pollutant: sulfur dioxide (SO₂)

• sources: coal-fired power plants, petroleum refineries, manufacture of sulfuric acid, and smelting of ores containing sulfur.

• health effects: eye irritation, wheezing, chest tightness, shortness of breath, lung damage.

pollutant: nitrogen dioxide (NO₂)

• sources: motor vehicles, electric utilities, and other industrial, commercial, and residential fuel burning sources.

• health effects: susceptibility to respiratory infections, respiratory symptoms, cough, chest pain, difficulty breathing.

pollutant: ground-level ozone (O₃)

• sources: vehicle exhaust and other air pollutants in the presence of sunlight.

• health effects: eye and throat irritation, coughing, respiratory tract problems, asthma, lung damage.

pollutant: lead (Pb)

• sources: metal refineries, lead smelters, battery manufacturers, iron and steel producers.

• health effects: anemia, high blood pressure, cancer, brain and nervous system impairment, kidney damage.

pollutant: particulate matter (PM)

• sources: diesel engines, power plants, industries, dust, wood stoves.

• health effects: eye irritation, respiratory problems, cancer, heavy metal poisoning, cardiovascular effects.

photochemical smog

• smog is a brownish haze produced by the photochemical reaction of sunlight with hydrocarbons, often called ozone pollution.

• the most noticeable adverse effects of smog are difficulty breathing, burning eyes, headaches, and nausea. 

air quality index (AQI)

• a measure of how clean or polluted the air is on a given day and if there are any health concerns related to the air quality.

• the AQI scale is from 0 to 500: the higher the AQI value, the greater the level of air pollution and health risks.

• AQI of 100 corresponds to the national air quality standard for the pollutant, the level the EPA has set to protect public health. 

• AQI below 100 are considered satisfactory. 

acid deposition

• acid deposition gradually acidifies ponds, lakes, and other bodies of water.

• acid deposition aggravates and causes bronchitis, asthma, and other respiratory problems.

• acid deposition can cause metals such as aluminum, cadmium, lead, and mercury to leach out of the soil. 

indoor air pollution

• air pollution levels within homes and other buildings is two to five times higher than outdoor pollution levels.

• indoor air pollution comes primarily from cooking stoves and furnaces, woodstoves and space heaters, household cleaners and solvents, mold, pesticides, asbestos, formaldehyde, radon, and lead.

• preventing indoor air pollution focuses on three areas:

  • source control - eliminating or reducing individual contaminants.

  • ventilation improvements - increasing the amount of outdoor air coming indoors.

  • air cleaners - removing particulates from the air.

environmental tobacco smoke

• the greatest source of indoor air pollution is environmental tobacco smoke, or secondhand smoke. 

radon

• the US surgeon general warns that radon is the second leading cause of lung cancer.

• the EPA estimates that as many as 21,000 lung cancer deaths per year are attributable to excess radon in the home. 

lead

• although banned in 1978, as many as 25 percent of US homes still have lead based paint hazards.

• nearly 535,000 children ages 1 to 5 in the US have blood lead levels above the 5mcg limit. 

• lead affect the circulatory, reproductive, urinary, and nervous systems, as well as the kidneys, and it can accumulate in bone and other tissues. 

global warming

• over the past 100 years, the average temperature of the earth has increased by 1.5F.

• projections indicate another 2F to 11.5F rise expected in the next 100 years.

human-caused global warming

• the amounts of greenhouse gas in the atmosphere rose dramatically around the time of the industrial revolution and correlated very closely with temerpature increase. 

• global sea levels rose 6.7 inches in the past 100 years, mostly in the past decade.

• the year 2016 was the warmest globally since records have been kept beginning in 1880.

• sixteen of the 17 warmest years on records have occurred since 2001. since 1981, 20 of the warmest years ever have occurred.

• Greenland is losing 36 to 60 cubic miles of ice per year, and Antarctica is losing 36 cubic miles of ice per year. 

the enhanced greenhouse effect

1. solar energy passes through the atmosphere, some is reflected back into space.

2. Earth’s surface is warmed by the sun and radiates heat back out toward space.

3. some heat passes through the atmosphere into space, but most is trapped by greenhouse gases and rereleased toward Earth, furtherwarming it.

4. human activites cause an increase in greenhouse gases, trapping more heat and intensifying the warming effect.

The Paris Agreement 2015

• nearly 190 nations, representing over 95 percent of the world’s greenhouse gas emissions, met in Paris to work toward slowing emissions and spurring the development of alternative energy sources.

• allowed countries to come up with their own intended nationally determined contributions (INDCs).

• under the Trump Administration 2017 the US exited the Paris Agreement. 

US intended national determined contribution (INDC)

• the US goal for INDC was to reduce net greenhouse gas emissions to 26 to 28 percent below 2005 levels by 2025.

• this would come from obtaining compliance with existing policies, along with additional technological advances and improvements.

alternative energy

• alternative energy refers to energy sources that do not utilize fossil fuels. including solar power, wind energy, geothermal, hydroelectric, biomass energy.

US gallons per capita per day (GPCD)

• we have seen imporvements in our GPCD water usage from agriculture, thermoelectric power, minicipal, and insustrail sources in the US, decling from 1900 GPCD in 1900 to 1100 in 2019. 

• we continue to exceed most nations of the world in water consumption.

• rediential use declined, however the average US family still uses over 300 gallons of water per day, 70 percent of which occurs indoors.

plastic pollution impact

• by 2050, our oceans will house more plastic than fish.

• we produce over 30 million plastic bottles globablly each day, 79 percent of which end up in landfills. 

• daily use plastics make for over 315 billion pounds of plastic in our likes, rivers, and oceans. 

• another 17 billion pounds to the mass added each year.

water pollution

• point source pollutants enter a waterway at a specific location through a pipe, ditch, culvert, or other conduit. 

  • major point source pollution sources include sewage treatment plants and industrial facilities.

• nonpoint source pollutants, known as runoff and sedimentation, drain or seep into waterways from broad areas of land. 

  • nonpoint source pollution results from a variety of land-use practices, including soil erosion and sedimentation, construction and engineering project wastes, pesticide and fertilizer runoff, urban street runoff, acid mine drainage, septic tank leakage, and sewage sludge.

major sources of water pollutants

• gasoline and petroleum products

• organic solvents

• fracking by-products

• polychlorinated biphenyls

• dioxins

• pesticides

water pollutants: gasoline and petroleum products

• leaks from underground storage tanks at filling stations; occupational exposures in processing plants and filling stations. furnaces can speak fires and cause respiratory issues

• today only 560,000 underground storage tank (UST) are still in operation, with over 70 percent compliance and much lower risk of contamination.

water pollutants: organic solvents

• chemicals designed to dissolve grease and oil; dry-cleaning fluids, paints, antifreeze, ect.

• consumers dump leftovers into the toilet or street drains, industries bury barrels that can leak.

water pollutants: fracking by-products

• chemicals used in hydraulic fracking, a method of extracting natural gas from the ground by forcing pressurized liquids into underground rock. 

water pollutants: polychlorinated biphenyls (PCBs)

• insulating materials in high-voltage electrical equipment such as transformers and fluorescent lights, no longer manufactured in the US.

water pollutants: dioxins

• formed as contaminant during certain industrial processes, such as the production of some herbicides, the incineration of waste, and the burning of fuels such as wood, coal, or oil.

water pollutants: pesticides

• chemicals designed to prevent, mitigate, or kill any pest, including insects, rodents, weeds, and microorganisms.

• can be dispersed by winds, water runoff, and food contamination. 

solid waste

• on average each day every person in the US generates nearly 4.5 pounds of municipal solid waste (MSW), or trash/garbage.

• this total to 262 million tons of trash each year, with paper, food, and plastics making up the largest share.

inadequate recycling

• although we recycle one-third of the waste we generate, experts believe that we could recycle up to 90 percent.

• currently 34.7 percent of all municipal solid waste in the US is recycled or composted, 12.8 percent is burned and the remaining 52.5 percent is disposed of in landfills.

strategies to reduce municipal solid waste (MSW)

• source reduction - altering the design, manufacture, or use of products and materials to reduce the amount and toxicity of water. 

• recycling - sorting, collecting, and processing materials for reuse in new products and diverts items such as paper, cardboard, glass, plastic, and metals from the waste. 

• composting - collecting organic waste, such as food scraps and yard trimmings, and allowing it to decompose with the help of microorganisms, producing a nutrient-rich substance used for soil enhancement. 

• combustion with energy recovery - the use of boilers and industrial furnaces to incinerate waste and use the burning process to generate energy. 

food waste

• over one-third of the world’s edible food is lost or wasted annually. 

• Americans are among the worst of food wasters, wasting over 40 percent of all edible food. 

• the average person in the US dumps over 20 pounds of food each month.

the Comprehensive Environmental Response, Compensation and Liability Act (superfund)

• enacted in 1980 to provide funds for cleaning up what the typically “abandoned” hazardous waste dump sites. 

• has since located and assessed tens of thousands of hazardous waste sites, worked to protect people and the environment, and involved communities and states in the cleanup.

• the vast majority of sites have been cleared or recovered with over 1729 final or deleted sites and 53 proposed sites needing cleanup as of July 2017.

nonionizing radiation

• radiation at the lower end of the electromagnetic spectrum, which moves in relatively long wavelengths. 

• includes radio waves, TV signals, cell phones, computer monitors, microwaves, and infrared waves.

• concerns have been raised about the safety of radio frequency waves generated by cell phones.

ionizing radiation

• caused by the release of particles and electromagnetic rays from atomic nuclei during process of disintegration. 

• naturally occuring elements such as uranium emit ionizing radiation, as well as the sun and its ultraviolet rays. 

radiation exposure

• measured in radiation-absorbed doses (rads), can cause damage at doses as low as 100 to 200 rads. 

• at 350 to 500 rads, symptoms of nausea, diarrhea, fatigue, anemia, sore throat, and hair loss become more severe and death may result because the radiation hinders bone marrow production of the white blood cells.

• doses above 600 to 700 rads are fatal. 

safe radiation exposure

• recommended maximum safe exposure to radiation ranges from 0.5 to 5 rads per year.

• approximately 50 percent of the radiation to which we are exposed comes from background sources.

  • including natural sources like radon gas in the air and cosmic radiation.

  • also include human-made sources such as certain building materials.

• another 45 percent comes from medical and dental x-rays.

• the remaining 5 percent is non-ionizing radiation that comes from sources such as computer monitors, microwave ovens, televisions, and radar screens. 

nuclear power plants

• proponents of nuclear energy believe that it is a safe and efficient way to generate electricity.

• the initial costs of building nuclear power plants are high, but actual power generation is relatively inexpensive in comparison to other forms.

• nuclear power causes reduction in fossil fuel use in heating and discharges less carbon into the air than fossil-fuel powered generators.

• however, disposal of nuclear waste poses significant risks to our environment.