Human Impact

Do Now 1. List three ways humans have impacted the environment. Section 6-3 1. List three ways humans have impacted the environment. 2. Do you think humans have had a positive impact or negative impact? Explain your answer. 3. Do you think it is important to preserve our environment? What can we do to preserve our environment? Go to Section:

Changing landscape Past and present humans have had a powerful influence on the physical and living world by modifying their environment. Our practices have changed the environment! From deforesting to fishing We used the environment for food, medicine, wood, and fiber We introduced new species, predators, agriculture, industry, and disease The world is very different from what it was long ago. Think of Earth as an island – all of the organisms that live on Earth share limited resources and increasing population sizes place greater demands on the biosphere

Human Activities Humans have advantages in competing with other species for limited resources (food, energy, and space) Humans are the most important source of environmental change on the planet, because we can change the flow of energy in an ecosystem and reduce the ability of ecosystems to recycle nutrients Human activities that have transformed the biosphere include: Hunting and gathering Agriculture Industry and urban development Technology

Human Impact Hunting and Gathering – the primary means of survival for most of human history, changed environment by diverting water, burning grasslands to grow certain plants, and causing major mass extinctions

Human Impact Agriculture – farming began about 11,000 years ago supplying a dependable food source and beginning civilization development Domestication of animals  provides humans’ energy to do work  overgrazing (changing ecosystem) Human population growth  strain on world’s food supply  Green Revolution (new farming practices with increased yields and new hardier strains of plants)

Human Impact Industrial growth and Urban development – added machines and factories to civilization during 1800s creating cities Industrial Revolution (increased productivity and scientific knowledge)  increased energy use (coal, oil, gas)  increased waste/pollution (air, water, soil) and stress on natural habitats

Quick Activity Classify the following resources as renewable or nonrenewable with your seat partner: Solar energy Wind/air Water Fossil fuels Metals Soil Plants Animals } Biodiversity

Resources Environmental resources can be classified as: Renewable = regenerate and replaceable (trees, water), but not necessarily unlimited The classification “renewable” depends upon the context in which you use it. (For example, a forest is not renewable, because the climate would change if all trees were cut down, but individual trees are renewable) Nonrenewable = cannot be replenished by natural processes (fossil fuels, coal, oil, natural gas)

Renewable resources Human activities affect the supply and the quality of renewable resources including: Land resources Forest resources Ocean resources Air resources Water resources

Land Resources Provide space for cities and suburbs, raw materials for industry, and fertile soil with nutrients and moisture to grow plants with roots to hold soil against rain and wind Negative activities: Soil erosion = wearing away of surface soil by water and wind (usually results from removing roots that hold soil) Desertification = turning once productive areas into deserts (usually results from farming, overgrazing, and drought) Positive activities: Sustainable agriculture = reduces soil erosion by conserving soil’s properties

Sustainable Agriculture Section 6-4 Cover Crops Legumes, grasses, and other cover crops recycle soil nutrients, reduce fertilizer need, and prevent weed growth. Controlled Grazing By managing graze periods and herd densities, farmers can improve nutrient cycling, increase the effectiveness of precipitation, and increase the carrying capacity of pastures. Biological Pest Control The use of predators and parasites to control destructive insects minimizes pesticide use as well as crop damage A B C Contour Plowing Contour plowing reduces soil erosion from land runoff. On hilly areas, plowing is done across the hill rather than straight up and down. Yr. 1 Crop Rotation Different crops use and replenish different nutrients. By rotating crops, the loss of important plant nutrients is decreased. corn oats alfalfa Yr. 2 alfalfa (plowed in) corn alfalfa Yr. 3 oats alfalfa corn Go to Section:

Forest resources Provide wood for homes, paper, fuel and “lungs of the Earth” because they remove carbon dioxide and produce oxygen, store nutrients, provide habitats and food, moderate climates, limit soil erosion, and protect fresh water supplies Negative activities: Deforestation = loss of forests leading to soil erosion Positive activities: Tree farms = plant, promote growth, manage, harvest and replant trees to preserve the ecosystem

Ocean resources Provides protein-rich food (cod and shrimp) Negative activities: Overfishing = fish are being harvested faster than they can reproduce Positive activities: Limit the catch of fish populations Aquaculture = farming of aquatic organisms

Amount of Fish per Person Growth of Fish Catch Larger fishing boats with better technology for locating and catching fish Section 6-2 World Fish Catch World Fish Catch per Person Total Catch (million tons) Amount of Fish per Person (kilograms) Year Year Go to Section:

Air resources Used to breathe Negative activities: Pollutant = harmful material that can enter the biosphere through the land/air/water Smog = mixture of chemicals that results in a gray-brown haze in the atmosphere mostly due to car exhausts and industrial emissions causing respiratory conditions Acid rain = mixture of acidic gases (nitrates and sulfates) from combustion with water vapor damaging plants, soil and water Positive activities: Clean-air regulations and controlling emissions has improved air quality

Chemical Transformation Emissions to Atmosphere The Formation of Acid Rain Section 6-2 Chemical Transformation Nitric acid Sulfuric acid Condensation Emissions to Atmosphere Nitrogen oxides Sulfur dioxide Dry Fallout Precipitation Acid rain, fog, snow, and mist particulates, gases Industry Transportation Ore smelting Power generation Go to Section:

Water resources Billions of gallons of water are used daily by Americans for drinking, washing, watering crops and making steel (“everyday use”) Negative activities: Our renewable water supply can be limited by drought, overuse, oil spills, improperly discarded chemicals and waste (sewage) Positive activities: Protect natural cycles because plants naturally filter and purify water = Fresh Water Wetlands Act Water conservation Clean Water Act

Which would you rather swim in? Why?

Which would you rather live in? Why?

Do Now Section 6-3 1. List three ways in which other organisms have proved to be a benefit to humans. 2. Compare biodiversity with other natural resources, such as wood and fossil fuels. Do you think biodiversity is a renewable or a nonrenewable resource? Explain your answer. 3. What can be done to preserve the biodiversity of organisms? Go to Section:

Biodiversity Biological diversity or “Biodiversity” = the sum total of the genetically based variety of all organisms in the biosphere Our existence relies on a great variety of other organisms. Some branches within biodiversity: Ecosystem diversity = variety of habitats, communities, and ecological processes in the living world Species diversity = number of different species in the biosphere (about 1.5 million discovered) Genetic diversity = sum total of all the different forms of genetic information carried by all organisms living on Earth today

Species Diversity Insects Protists Other Animals Plants Bacteria Fungi Section 6-3 Insects 54.4% Protists Other Animals 4.2% 19.7% Plants 18% Bacteria Fungi 0.3% 3.4% Go to Section:

Value of Biodiversity Biodiversity is one of Earth’s greatest natural resources providing us with food, industrial products, and medicines (painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs) When biodiversity is lost, potential sources of material with significant value to the biosphere and to humankind may be lost.

Threats to Biodiversity Human activities can reduce biodiversity by: Habitat alteration Hunting species to extinction Extinction = occurs when a species disappears from all or part of its range Endangered species = species in danger of extinction with declining population sizes As the population declines, the species loses genetic diversity, making it more vulnerable to extinction Introducing toxic compounds (pollutants) into food webs Introducing foreign species to new environments

Habitat Alteration When land is developed, natural habitats may be destroyed and the species that live in those habitats may vanish Habitat fragmentation = development of land that splits ecosystems into pieces resulting in biological “islands” with fewer species and smaller populations more vulnerable to further disturbances or climate changes

Hunting In the past, hunting for meat, fur, hides or other body parts caused the extinction of some species Today, endangered species are protected from hunting by laws in most of the world

Pollution Pollution can threaten biodiversity, because toxic compounds accumulate in tissue of organisms Biological magnification = increasing concentrations of harmful substances at higher trophic levels in a food chain/web Entire food web is affected, but top-level carnivores are at highest risk

Biological Magnification of DDT Section 6-3 Magnification of DDT Concentration Fish-Eating Birds 10,000,000 Large Fish 1,000,000 100,000 Small Fish 10,000 Zooplankton 1000 Producers Water 1 Go to Section:

Introducing Foreign Species Biodiversity is also threatened by apparently harmless plants and animals that humans transport around the world either accidentally or intentionally Invasive species = organisms introduced into new habitats and reproduce rapidly lacking the parasites and predators that control population size in their native country They can displace native species driving them close to extinction Ex. Zebra Mussels

Conserving Biodiversity Conservation = wise management of natural resources Preservation of habitats and wildlife to protect Earth’s biodiversity for future generations, however protected areas may not be enough Current conservation efforts focus on protecting individual species as well as entire ecosystems (to ensure natural habitats and interactions among different species are preserved). “Hot spots” = places around the world where everything possible is being done to conserve the ecosystem and species

Our Future Since the human population is rapidly increasing, we are creating greater environmental changes. Two major concerns are: Ozone depletion Global warming

Ozone Depletion Ozone layer = a layer of concentrated ozone gas made up of three oxygen molecules (O3) between 20 and 50 kilometers above Earth’s surface absorbing harmful UV radiation Ozone holes caused by CFCs (chlorofluorocarbons) breaking down ozone molecules Increased UV radiation can cause cancer, eye damage, decreased resistance to disease, and tissue damage to plants and animals

Global Warming A 0.5°C increase in the average temperature of the biosphere in the past 120 years (abiotic factor) Some scientists believe the rising temperature may be due to natural variations in climate Others believe it is caused by human activities adding carbon dioxide and other greenhouse gases into the atmosphere, making the atmosphere retain more heat More carbon dioxide from burning fossil fuels, cutting down trees and burning forests It may result in rising sea level causing more frequent and more severe weather disturbances Environmental changes benefit some species, but greatly disturb others that may not survive

The Value of a Healthy Biosphere A healthy biosphere provides us with many valuable goods and services (food, medicine, temperature control, water purification, soil formation, etc) Make wise choices about resources used, disposal, recycling, and energy conservation

Ecosystem services are provided, but it’s your responsibility to help save the Earth! Section 6-4 Solar energy Production of oxygen Storage and recycling of nutrients Regulation of climate Purification of water and air Storage and distribution of fresh water Food production Nursery habits for wildlife Detoxification of human and industrial waste Natural pest and disease control Management of soil erosion and runoff Go to Section: