Environmental Problems Exam 2

The Science Behindthe Story

Predicting the Oceans' "Garbage Patches" -Nikolai Maximenko at the International Pacific Research Center at the University of Hawaii at Manoa studies ocean currents -in 2008, he partnered with Peter Niiler of the Scripps Institution of Oceanography -combined data from the Global Drifter Program with satellite altimetry and wind currents, produced a more detailed-simulation results revealed that oceanic debris accumulates in portions of five subtropical gyres-simulation results also predicted the fate of debris from the 2011 tsunami in northern Japan

Forest

any ecosystem with a high density of trees, e.g. Boreal forest: Canada, Scandinavia, and Russia

Nations often cooperate to resolve water disputes

depletion of fresh water leads to shortages, which can lead to conflict-261 major rivers cross national borders -transboundary disagreements are common -water is a key element in hostilities among Israel, Palestinians, and neighboring countries, Georgia, Alabama, and Florida are feuding over water, water diversions threaten downstream supplies-many nations have cooperated to resolve disputes-they sign water-sharing treaties -water basins that cross national boundaries have potential for conflict if water supplies become scarce

Many kinds of forests exist

eastern U.S. has 10 forest types - e.g. spruce-fir, oak-hickory, longleaf-slash pine western U.S. has 3 forest types - e.g. Douglas fir, Ponderosa pine, Pinyon-juniper

Forests cover 31% of Earth's surface

forests provide habitat, maintain soil, air and water, and are part of vital biogeochemical cycles, t hey also provide essential goods for humans, forests are ecologically complex

Point and non-point sources of pollution

pollution-the release of matter or energy that causes undesirable impacts on health and well-being of humans or other organisms -water pollution has many forms and can cause diverse impacts on aquatic ecosystems and human health -chemical indicators -pH, nutrient concentrations, dissolved oxygen concentration -physical indicators -temperature, turbidity (density of suspended particles in water)-biological indicators-presence of harmful microorganisms, species diversity-point sources-discrete locations of water pollution, factories, sewer pipes, oil tanker, addressed by the U.S. Clean Water Act -non-point sources-multiple inputs of pollution over larger areas (farms, city streets, neighborhoods)

We extract timber from private and public lands

- National forests - public lands set aside to grow trees, produce timber, protect watersheds, and ensure future timber supplies, 77 million ha (191 million acres) — 8% of U.S. land - The U.S. Forest Service was established in 1905 - manages forests for the greatest good of the greatest number in the long run, we should wisely and carefully use resources from public lands - federal agencies own and manage over 600 million acres- most logging is on private land - timber companies cut national and state forests - the Forest Service manages timber sales and builds roads, companies log and sell the timber for profit, taxpayers subsidize private timber harvesting on public land - National forest harvesting has declined- Regrown forests are ecologically less valuable

Federal parks and reserves began in the U.S

- National parks - public lands protected from resource extraction and development, open to nature appreciation and recreation, Yellowstone National Park was established in 1872 - the National Park Service (NPS) administers parks 392 sites on 84 million acres, historic sites, recreation areas, seashores, etc. - national parks are the "best idea we've ever had"- National Wildlife Refuge - havens for wildlife, begun in 1903 by President Theodore Roosevelt, 61 million ha (151 million acres) in 550 sites, administered by the U.S. Fish and Wildlife Service (USFWS), allows hunting, fishing, birding, wildlife observation, photography, education - Wilderness areas - off-limits to development, allow hiking, nature study, other low-impact recreation, 750 areas, 44 million ha (110 million acres)

Plantation forestry has grown

- North America's timber industry focuses on plantations of fast-growing trees of single-species monocultures - plantations are not natural forests - simple communities that act more like crops, r educed complexity decreases habitat and biodiversity, vulnerable to pests - even-aged stands - all trees are planted at the same time - rotation time - time between cuts - uneven-aged stands - a mix of tree species and ages, more similar to natural forests

Management strategy: adaptive management

- adaptive management - testing different approaches and aiming to improve methods through time, monitoring results, adjusting methods as needed - fuses science and management - hypotheses about management are explicitly tested

Habitat fragmentation makes preserves vital

- agriculture, residential development, roads, logging, etc., divide habitat into small, disconnected fragments, species needing large habitats disappear (e.g., bears), areas are too small and isolated to be recolonized - edge effects - conditions created along a fragment's edge, parasites and predators easily attack bird nests, interior bird species can't reproduce when forced near the edge of a fragment - fragmentation is the main reason for decline of populations of North American songbirds

Forest management has evolved over time

- all logging affects the environment - disturbs the soil, changes habitat, and affects species, i ncreases erosion and degrades water quality, l andslides occur on clear-cut steep hillsides - increased awareness caused the public to urge that national forests be managed for: recreation, wildlife and ecosystem integrity, timber- National Forest Management Act (1976) - integrates harvesting methods with management goals to manage wildlife and restore degraded ecosystems - Hiawatha National Forest on Michigan's Upper Peninsula - established a management plan for renewable resources: carefully manage timber harvesting, monitor fish and wildlife populations, allow diverse recreation (hiking, fishing, boating, etc.), prohibit livestock grazing, protect historic and archaeological sites, and prohibit building of new roads, maintain habitats for threatened and endangered species and to restore wetlands, streams, forests, and soils, protect old-growth stands

Carbon storage limits climate change

- carbon storage by forests is of great international interest - trees absorb carbon dioxide and store carbon - forests store more carbon than the atmosphere - cutting forests worsens climate change - dead plants decompose and release carbon dioxide, fewer trees are left to soak up carbon dioxide - preserving forests keeps carbon out of the atmosphere

Climate change and pest outbreaks are altering forests

- climate change is worsening wildfire risk- pests kill huge areas of trees, particularly even -aged plantations, e.g. bark beetle has killed more than 30 billion conifer trees in western North America - some species will benefit, and others will be harmed - drier woodlands, shrublands, or grasslands may replace dense, moist forests

Solutions are emerging

- conservation organizations are buying concessions - to preserve, not cut, forests - POTICO (Palm Oil, Timber, and Carbon Offsets) - World Resources Institute (WRI) steers palm oil companies to already logged land, uncut forests are protected or sustainably logged - REDD: Reducing Emissions from Deforestation and Forest Degradation - wealthy nations pay poor nations to conserve forests, rich nations get carbon credits to offset emissions

Forest loss

- deforestation - the clearing and loss of forests, changes landscapes and ecosystems, reduces biodiversity, worsens climate change by adding carbon dioxide, disrupts ecosystem services - alteration, fragmentation, and outright loss of forests are one of society's primary challenges - especially as our population increases

We deforested much of North America

- deforestation propelled the expansion and growth of the U.S. and Canada - Primary forest - natural forest uncut by people, l ittle remained by the 20th century in the U.S. - Second-growth trees - trees that sprout after old-growth timber was cut - Secondary forest - contains second-growth trees Once deforested, timber companies move on - local loggers lose their jobs - the entire eastern half of the continent used to be covered in primary forest- most primary forest was cut for agriculture and timber

Many agencies and groups protect land

- each U.S. state has agencies that manage resources on public lands, c ounties and municipalities also do this - land trusts - local or regional organizations that purchase land to protect it, t he Nature Conservancy: the world's largest land trust, t rusts own 690,000 ha (1.7 million acres) and protect an additional 4.1 million ha (10.2 million acres), Big Sur, CA; Jackson Hole, Wyoming; Mount Desert Island, ME - thousands of volunteer groups care for protected land

Management strategy: ecosystem-based management

- ecosystem-based management - minimizes impacts on ecosystems and ecological processes - certified sustainable forestry plans - protect certain areas, restore ecologically important habitats, consider patterns at the landscape level, preserve the forest's functional integrity - it is challenging to implement this type of management - ecosystems are complex, our understanding of how they operate is limited

Forest management

- forestry - the practice of forest management, f orests are renewable if not exploited too quickly - foresters - professional managers who must balance: dDemand for forest products (short-term benefits) vs. the importance of forests as ecosystems (long-term benefits) - resource management - strategies to manage and regulate potentially renewable resources, sustainable management does not deplete resources, managers are guided by social, political, and economic factors

Forests are ecologically complex

- forests are some of the richest ecosystems for biodiversity - are structurally complex, with many niches, provide food and shelter for many species, fungi and microbes decompose plants and cycle nutrients - plant diversity leads to greater overall organism diversity - old-growth forests have higher diversity than younger forests - have higher structural diversity, microhabitats, and resources - A mature forest is complex in its structure

Forests provide valuable resources

- forests provide economically valuable resources - medicine, food, fuel, shelter, ships, paper- industrial harvesting has allowed us to extract more timber than ever before - boreal forests in Canada, Russia are logged, large areas of rainforest are also logged in Brazil, Indonesia, most U.S. logging is in southern pine plantations and western coniferous forests

Climate change threatens protected areas

- global climate change threatens to undo our efforts to design, establish, and guard protected areas - as temperatures warm, species' ranges shift northward - species can't move in a fragmented habitat- high -elevation species are at greatest risk, there is no place for them to go- corridors that allow movement become very important, reserves must be connected with corridors to save species- saving biodiversity must go beyond protecting areas

Parks and reserves are increasing internationally

- many nations have established national parks - they benefit from ecotourism, 158,000 protected areas cover 12.7% of the world's land - parks do not always receive necessary funding - they can't protect resources or provide recreation, "Paper parks" are areas protected on paper but not in reality - Biosphere reserves - land with exceptional biodiversity managed or designated by the United Nations, couple preservation with sustainable development, must benefit local people, Biosphere reserves have several zones - World heritage sites - another type of international protected area, listed for their natural or cultural value, over 1000 sites in 150 countries - Transboundary parks - protected land overlapping national borders, example: 3 African nations share a mountain gorilla reserve, "Peace parks" - transboundary parks that ease tensions by acting as buffers between quarreling nations - ocean protected areas and reserves are also being created

Resource managers follow several strategies

- maximum sustainable yield - aims to achieve the maximum amount of resource extraction without depleting the resource from one harvest to the next - a population grows fastest at an intermediate size - at half its carrying capacity - harvesting to keep the population at this size results in maximum harvest while sustaining the population - management strategy: maximum sustainable yield presents concerns - managed populations are much smaller than they would naturally be, reducing populations so drastically affects other species (changes the entire dynamic of the community), trees are cut long before they grow to maximum size (changes forest ecology, eliminates habitats)

Forests are being cleared most rapidly in developing nations

- most deforestation is in Latin America and Africa - settlements for more people, resource extraction and sales overseas, fuelwood for cooking and heating - European and North American forests are recovering from past deforestation - Brazil is home to most of the Amazon rainforest - shows success in reducing deforestation but has continuing pressures - Concession - foreign corporations pay a government for the right to extract resources, little incentive to conserve forests - economic benefits of deforestation are short term - temporary jobs are soon lost, along with the resources, wood is exported to North America and Europe - Asian palm oil plantations - replacing tropical forests, palm oil is used in snack foods, soaps, cosmetics(it also replaces fossil fuels), clearing forests encourages further development (increases illegal logging), plantations displace natural forests

Forests provide ecosystem services

- priceless ecosystem services - prevent erosion, recharge aquifers, purify water, produce oxygen, influence weather, return organic material to the soil as litter - forests also enhance our quality of life - culture, aesthetics, health, recreation, adventure

Sustainable forestry is gaining ground

- sustainable forest certification - granted to forests, companies, and products made using sustainable methods, t he Forest Stewardship Council (FSC) has the strictest standards, products are costly, but consumers willingly pay more, Home Depot and others sell sustainable wood, encouraging better logging practices - the world is still losing forests, but sustainable forestry is increasing

Fire can hurt or help forests

- the Forest Service used to suppress all fires- but many ecosystems depend on fires - for seed germination, grassland preservation, animal diversity and abundance, excess vegetation produces kindling for future fires - Fire suppression leads to catastrophic fires, damages property, hurts forests, threatens people, have become more numerous recently - wildland-urban interface - housing developments are placed near forests, vulnerable to forest fires- prescribed (controlled) burns - burning areas of forests under carefully controlled conditions, remove fuel loads, nourish soil, encourage growth of new vegetation - salvage logging - removal of dead trees following a natural disturbance (fire, windstorm, insects, disease), seems logical, but actually is destructive, s nags (standing dead trees) provide food, nesting and roosting cavities for animals, removing timber from recently burned areas increases erosion and soil damage, impedes forest regeneration and promotes future fire

Reserve design has consequences for diversity

- the SLOSS dilemma: given fragmentation and limited land..., is it better to protect a single large or several small reserves?, s ingle large area for large animals who migrate, smaller areas are fine for insects - corridors of protected land allow animals to travel between islands of habitats, should allow access to more habitat, should encourage gene flow, many land managers now try to establish corridors to join new reserves to existing reserves

Why create parks and reserves?

- we must preserve functional ecosystems by setting aside protected lands, 12% of all land is under some sort of protection - people establish parks and reserves to: preserve enormous or unusual scenic features, offer recreational value: hiking, fishing, hunting, etc., generate revenue from ecotourism, offer peace of mind, health, exploration, wonder, etc., provide benefits and ecosystem services, preserve biodiversity

Freshwater meets saltwater in estuaries

-67% of all people live within 100 miles of the ocean -estuaries-water bodies where rivers flow into the ocean, mixing fresh water with saltwater -shallow water nurtures plants that provide critical habitat for shorebirds and shellfish -estuaries are affected by development, pollution, habitat alteration, and overfishing

Water supplies houses, industry, and especially agriculture

-70% of our water use is for agriculture-crop irrigation, watering of livestock, 20% goes to industry, 10% for residential use -consumptive use-water is removed from an aquifer or surface water body and is not returned (e.g., irrigation) -nonconsumptive use-does not remove, or only temporarily removes, water, electricity generation at hydroelectric dams

Central Case Study: Starving the Louisiana Coast of Sediment

-Louisiana's vital coastal wetlands -support biodiversity, protect the coast from storms -Mississippi River sediments -keep soil levels high, water stable, and plants healthy -wetlands are shrinking -dams stop sedimentation, levees prevent water from spreading into the delta -Why are Louisiana's wetlands disappearing?-oil and gas extraction promote wetland losses -withdrawal compacts land and lowers soil levels, canals fragment wetlands and increase erosion, oil spills destroy vegetation-diverting the Mississippi River -can restore the wetlands, will cost millions

Other factors warm or cool the surface

-aerosols-microscopic droplets and particles, they have either a warming or a cooling effect -soot(black carbon aerosols) causes warming by absorbing solar energy -but most tropospheric aerosols cool the atmosphere by reflecting the sun's rays -sulfate aerosols from fossil fuel combustion may slow global warming, at least in the short term -volcanic eruptions reduce sunlight reaching Earth's surface and cool the Earth -radiative forcing-the amount of change in thermal energy that a given factor causes, positive forcing warms the surface, negative forcing cools it -earth is experiencing radiative forcing of 1.6 watts/m2more thermal energy than it is emitting into space

Greenhouse gases warm the lower atmosphere

-as Earth's surface absorbs solar radiation, the surface temperature increases and emits infrared radiation -greenhouse gases-atmospheric gases that absorb infrared radiation, water vapor, ozone, carbon dioxide, nitrous oxide, methane, halocarbons (chlorofluorocarbons [CFCs]) -greenhouse gases re-emit infrared energy-some energy is lost to space -greenhouse effect-the energy that travels downward warms the atmosphere and the planet's surface -greenhouse gases differ in their ability to warm the trophosphere and surface -global warming potential-the relative ability of one molecule of a greenhouse gas to contribute to warming, expressed in relation to carbon dioxide (potential 1), Nitrous oxide is 298 times as potent as carbon dioxide -carbon dioxide contributes most to the greenhouse effect-it is less potent, but far more abundant, than other gases, the major type of human-caused emissions

Temperatures continue to rise

-average surface temperatures increased 0.9°C in the past 100 years-most of the increase has occurred since 1975, since 2000, we have experience 13 of 15 warmest years

Biodegradable wastes

-biodegradable materials decrease dissolved oxygen in water-human waste, animal manure, paper pulp, yard wastes (grass clippings, leaves) -wastewater-humans release biodegradable wastes, from toilets, showers, sinks, dishwashers, washing machines, industrial cleaning processes, stormwater runoff -developed nations treat wastewater-many developing nations don't treat wastewater

Fishing practices damage the oceans

-bycatch-the accidental capture of nontarget animals, kills millions of animals each year -driftnetting drowns dolphins, seals, sea turtles, and nontarget fish -longline fishing kills turtles, sharks, and seabirds-bottom -trawling is likened to clear-cutting and strip mining-it destroys complex communities (e.g., reefs)

What is climate change?

-climate change is the fastest-developing area of environmental science -climate-an area's long-term atmospheric conditions, temperature, precipitation, wind, humidity, etc. -weather-short-term conditions at localized sites-global climate change -describes modifications in Earth's climate, changes in temperature, precipitation, storm frequency -global warming and climate change are not the same

Models help us predict the future

-climate models-combine data from atmospheric and ocean circulation and interactions, to simulate climate processes -if a model accurately reconstructs current climate it may accurately predict future climate -modeling is hard because climate and feedback loops are so complex

Enforcement of water quality needs money

-conditions improve when citizens push their government to take action-underfunded and understaffed state and federal regulatory agencies cannot investigate violations -violations of the Clean Water Act have risen, 10% of Americans are exposed to unsafe drinking water, the new EPA administrator has promised improvement

Coral reefs are treasure troves of biodiversity

-coral reef-amass of calcium carbonate composed of the skeletons of millions of tiny, invertebrate corals, protect shorelines by absorbing waves -corals-tiny organisms living in shallow subtropical or tropical waters, related to jellyfish and use tentacles to catch food, derive nourishment from symbiotic algae, zooxanthallae -coral reefs are valuable ecotourism destinations

We have erected thousands of dams

-dam-any obstruction placed in a river or stream to block the flow of water, erected to prevent floods, provide drinking water, allow irrigation, and generate electricity, 45,000 large dams have been erected in more than 140 nations -reservoirs-artificial lakes created by dams, store water for human use, only a few major rivers remain undammed-in remote regions (Canada, Alaska, Russia, Africa)

Industrialized fishing uses several methods

-driftnets-transparent, nylon nets that span large expanses of water to capture passing fish -longline fishing-uses extremely long lines with thousands of hooks -bottom-trawling-entails dragging immense nets through the water or on the ocean floor

Current and future trends and impacts

-evidence that climate has changed is everywhere-fishermen in the Maldives, ranchers in Texas, homeowners in Florida, etc. -we cannot blame any single weather event on climate change-but extreme weather is part of a pattern backed by an immense volume of scientific data

People build dikes and levees to control floods

-flooding-a normal, natural process in which water spills over a river's banks, spreads nutrient-rich sediments over large areas -dikes and levees(long, raised mounds of earth) along the banks of rivers hold water in channels -dikes and levees make floods worse by forcing water to stay in channels, which then overflow

Global warming

-global warming-an increase in Earth's average temperature, only one aspect of climate change -earth's climate has varied naturally through time -today's climate change is happening at an extremely rapid rate, these changes are due to human fossil fuel combustion and deforestation-understanding climate change requires understanding how our planet's climate works

Bottled water has ecological costs

-groundwater is being withdrawn for bottled water-an average American drinks 30 gallons/year -people drink bottled water for portability, convenience-they think it tastes better or is healthier-bottled water is no better than tap water -energy costs are 1000 to 2000 times more than those of tap water-manufacturing the bottle, transporting the product-75% of bottles (30-40 billion/yr) are thrown away and not recycled

Groundwater can also be depleted

-groundwater is easily depleted -aquifers recharge slowly, we are mining aquifers -as aquifers are mined-water tables drop, and freshwater wetlands dry up, water becomes harder and more expensive to get, saltwater intrudes into coastal aquifers, compacted soil loses porosity, making recharge harder -sinkholes-occur when aquifers losewater; the land above can't support strata, and the surface sinks

Groundwater plays a key role in the water cycle

-groundwater-water beneath the surface heldin pores in soil or rock, 20% of the Earth's supply of fresh water -aquifers-porous formations of rock, sand, or gravel that hold water -zone of aeration -pore spaces are partly filled with water -zone of saturation-spaces are filled with water-water table-boundary between the two zones -groundwater may occur in unconfined aquifers above impermeable layers or in confined aquifers under pressure between impermeable layers.

Reducing household and industrial demand

-households-install low-flow faucets, showerheads, washing machines, and toilets, capture and store rain runoff from roofs, xeriscaping-replacing exotic plants with native plants adapted to local precipitation patterns -industry and municipalities-shift to processes that use less water, recycle wastewater for irrigation and industrial uses, fix leaky pipes, and retrofit homes with better plumbing, audit industries, and promote conservation

Fishing has industrialized

-how can the fisheries' catch seem to be stable, when fisheries are collapsing?-fleets are fishing in increasingly remote areas, they are engaging in more intensive fishing, they are capturing smaller fish than before, they are capturing less desirable species -today's industrialized fishing fleets -are huge vessels that use powerful technologies to capture fish in huge volumes

Excessive water withdraws can drain rivers and lakes

-in many places, we are withdrawing water at unsustainable rates -major rivers (e.g., the Colorado) run dry before reaching the sea -reduced flow has devastating consequences-drastically changes the river's ecology and plant community and destroys fish and invertebrates

Municipal sewer systems

-in populated areas, municipal sewer systems carry wastewater to wastewater treatment plants -primary treatment-removes suspended solids -secondary treatment-water is stirred and aerated, aerobic bacteria degrade organic pollutants, further treatment may remove particular pollutants -clarified water is treated with chlorine (or ultraviolet light)-effluent: treated wastewater -is piped into rivers or the ocean, may be used for lawns, irrigation, or industry

The future will be even hotter

-in thenext 20 years, temperatures will rise 0.4C-at the end of the 21st century, temperatures will be 1.8 to 4.0C higher than today's -we will have unusually hot days and heat waves-polar areas will have the most intense warming-sea surface temperatures will rise -hurricanes and tropical storms will increase in power and duration -projected increases in surface temperature for 2081-2100 relative to 1986-2005

Intertidal zones undergo constant change

-intertidal(littoral) zones-where the ocean meets the land, between the farthest reaches of the high and low tides -tides-periodic rising and falling of the ocean's height due to the gravitational pull of the moon and sun, organisms spend part of their time submerged in water and part of their time exposed to sun and wind -life abounds along rocky shorelines because environmental conditions change dramatically

Kelp forests harbor many organisms

-kelp-large brown algae growing from the floor of continental shelves along temperate coasts, can grow to 200 ft tall, forming "forests", provide shelter and food for organisms, absorb wave energy and protect shorelines from erosion -kelp serves as food and as thickeners in cosmetics, paints, paper, and soaps

Lakes and ponds are ecologically diverse systems

-lakes and ponds-bodies of standing surface water, they have several zones -littoral zone-nutrient-rich edge of a water body, rooted aquatic plants grow in this shallow part -benthic zone-extends along the bottom of the water body, home to many invertebrates -limnetic zone-open portion of the lake or pond where sunlight allows photosynthesis, open water below this zone has no photosynthesis and supports fewer animals because there is less oxygen -oligotrophiclakes and ponds-have low-nutrient and high-oxygen conditions, they can transform into -eutrophiclakes and ponds-have high-nutrient and low-oxygen conditions-eventually, water bodies fill in completely through the process of aquatic succession-eutrophication can also result from human-caused nutrient pollution

Oil pollution

-large spills are infrequent but can be devastating -other sources-natural seepage, boat leakage, road and parking lot runoff, spills during transport and leakage during extraction -in 1989, the oil tanker Exxon Valdez ran aground-polluted Prince William Sound along the Alaskan coast -in 2010, the Deepwater Horizon drilling platform exploded-polluted Louisiana, Mississippi, Alabama, Florida

Marine reserves protect ecosystems

-management was based on maximum sustained yield-number of fish that can be harvested without reducing future catches, despite management, stocks have plummeted -it is time to rethink fisheries management-ecosystem-based management-shift the focus away from species and toward the larger ecosystem -protecting ocean areas helps species recover-protect 20-50% of the ocean as no-take areas -marine protected areas(MPAs)-established along the coastlines of developed countries, still allow fishing or other extractive activities -marine reserves-areas where fishing is prohibited, leave ecosystems intact, without human interference, improve fisheries: young fish disperse into surrounding areas, many commercial and recreation fishers do not support reserves -reserveswork: species density, biomass, size, and diversity all increased 1-2 years after establishment

Mangrove forests occur in the tropics

-mangrove forests line sandy coasts in tropical and subtropical latitudes -mangroves-salt-tolerant trees with unique roots, roots curve up for oxygen and down for support, habitat for fish, shellfish, birds, protect coastlines from storms, filter pollutants, stabilize soils, protect coral reefs, produce food, medicine, tools, wood -50% of mangroves have been destroyed for resorts or shrimp farms

Wetlands can aid wastewater treatment

-microbes "polish" treated wastewater-remove plant nutrients -cleansed water is released into waterways -or percolates underground, the U.S. has over 500 artificial or restored wetlands -releasing wastewater effluent can help restore marshes-nutrients increase marsh grass growth, increased organic matter offsets natural soil compaction

Agricultural demand can be reduced

-most water is used in agriculture-"Flood and furrow" method floods fields, but plants use only 40% of the water applied -use efficient irrigation methods-low-pressure spray irrigation sprays water downward, drip irrigation systems target individual plants -match crops to land and climate-don't grow cotton, rice, or alfalfa in arid areas -use selective breeding and genetic modification to produce crops that require less water

Melting ice has far-reaching effects

-mountaintop glaciers are disappearing-glaciers on tropical mountaintops have disappeared, the remaining 25 of 150 glaciers in Glacier National Park will be gone by 2030, reducing summertime water supplies to millions -melting of Greenland's Arctic ice sheet is accelerating-warmer water is melting Antarctica's coastal ice shelves, interior snow is increasing because of more precipitation -melting ice exposes darker, less-reflective (lower albedo) surfaces, causing even more melting-nations are rushing to exploit underwater oil and mineral resources made available by newly opened shipping lanes-permafrost(permanently frozen ground) is thawing -destabilizing soil, buildings, etc., and releasing methane

Ocean currents affect Earth's climate

-movementof ocean water affects global climate-Thermohaline circulation -aworldwide current system, warmer, fresher water moves along the surface, colder, denser, saltier water moves below the surface -North Atlantic Deep Water(NADW)-one part of this system, warm water from the Gulf Stream flows across the Atlantic Ocean, warming Europe, water cools, becomes saltier, and sinks, creating a region of downwelling-interrupting the thermohaline circulation can trigger rapid climate change -global warming could melt Greenland's ice sheet, freshwater runoff into the North Atlantic would make surface waters less dense, this could stop the NADW formation, Europe would cool rapidly -some evidence shows circulation in this area is slowing-others say there will not be enough runoff to cause a shutdown this century -El Niño-Southern Oscillation(ENSO)-ashift in atmospheric pressure, sea surface temperature, and ocean circulation-normally, winds blow westward, piling up" water in the western Pacific, deep, cold water rises and brings up nutrients, Peru and Ecuador have rich fisheries-decreasing air pressure in the eastern Pacific-triggers El Niño, suppresses upwelling on the America's Pacific coast, devastates fisheries and costs billions of dollars

Nutrient pollution

-nutrient pollution from fertilizers, farms, sewage, lawns, golf courses leads to eutrophication and hypoxia-excess nitrogen and phosphorus in water boosts algal and aquatic plant growth, spreading algae cover the surface, decreasing sunlight, bacteria eat dead plants, reducing dissolved oxygen, fish and shellfish die -solutions include treating wastewater, reducing fertilizer application, and using phosphate-free detergents-planting vegetation decreases nutrient flow into water -human activities dramatically increase the rate at which eutrophication occurs -harmful algal blooms(red tides)-excessive nutrients increase marine algae, which release powerful toxins, kill organisms and people, decreases tourism, fishing

Corals are experiencing alarming declines

-nutrient pollution promotes algal growth-smothering corals -coral bleaching-Zooxanthellae die or leave corals, depriving them of nutrition, results from warmer water from climate change, pollution, eutrophication -Ocean acidification-oceans absorb excess CO2, lowers the pH of seawater, reduces carbonate ions and dissolves calcium carbonate in coral shells

Acidifying oceans imperil marine life

-ocean acidification-caused by increased CO2, organisms can't build their exoskeletons -oceans have already decreased by 0.1 pH unit, they will decrease 0.15 to 0.35 more units -enough to kill most coral reefs, which will be catastrophic -coral reefs are habitat for marine species, are tourism destinations, and protect coastlines -warmer waters contribute to coral bleaching-which kills corals

Modern fishing fleets deplete marine life rapidly

-oceans contain only one-tenth of the large-bodied animals they once held -overfishing has caused many fisheries to collapse, destroying fishing economies-groundfish (e.g., cod, haddock, halibut, flounder) stocks collapsed, bans in the 1990s by the U.S. and Canada have helped restore fisheries, aslow path to recovery -red snapper stocks have been overfished and depleted in the Gulf of Mexico-current populations are only 3% of historic levels

The physical makeup of the ocean is complex

-oceanstouch and are touched by every system-they receive all inputs, sediment, pollutants, organisms -oceans cover 71% of Earth and hold 97% of surface water-ocean water is 96.5% water, plus dissolved salts -surface water is warmer than subsurface water -warmed by the sun and is less dense -deeper water is dense and sluggish -unaffected by winds, storms, sunlight, and temperature-currents-vast riverlike flows in the upper 1,300 feet, driven by wind, heating/cooling, gravity, density differences, and the Coriolis effect -upwelling-the rising of cold, deep water to the surface, rich in nutrients, high primary productivity and lucrative fisheries -downwelling-the sinking of warm, oxygen-rich water, provides oxygen for deep-water life-the seafloor topography can be rugged and complex-underwater volcanoes, steep canyons and deep trenches, the planet's longest mountain range is under water -many parts of the ocean floor are rugged and complex

The fate of solar radiation

-our planet receives about 340 watts of electricity per square meter from the sun -and it naturally reflects and emits the same amount

Pathogens and waterborne diseases

-pathogens enter water through inadequately treated sewage and animal waste from feedlots -biological pollution causes more human health problems than any other type of water pollution -1 billion people don't have safe water, 2.6 billion don't have adequate sewer or sanitation facilities -solutions -disinfecting drinking water and treating wastewater, public education to encourage personal hygiene, government regulations protecting food

Water pollution and its control

-people affect aquatic ecosystems by withdrawing too much water, adding toxic substances or disease-causing organisms -developed nations have cleaned up water pollution-still, half of the world's major rivers are seriously depleted and polluted -surrounding ecosystems are being poisoned, people's health and livelihood are threatened -the invisible pollution of groundwater has been called a "covert crisis"

Emptying the oceans

-people are overharvesting marine species-threatens the balance and functioning of marine and coastal ecosystems -half of the world's marine fish populations are fully exploited-28% of fish populations are overexploited and heading to extinction, with current trends, populations of all ocean species we fish for will collapse by 2048

We divert surface water for our needs

-people divert water from rivers and lakes to farm fields, homes, and cities -the world's largest diversion project is in China-goal is to move water from water-rich northern China to drier farms and cities in southern China, 3 sets of massive aqueducts (1550 miles long) are being built -critics say not enough water can be moved-the project will cause huge environmental damage, it will displace hundreds of thousands of people

Nets and plastic debris

-plastic items dumped into the sea harm or kill wildlife-examples: fishing nets, plastic bags and bottles, fishing line, buckets, floats, mammals, seabirds, and sea turtles eat plastic and die -plastic trash is accumulating in gyres, ocean regions where currents converge-North Pacific's Great Pacific Garbage Patch -Congress passed the Marine Debris Research, Prevention, and Reduction Act in 2006-minimize this harm by reducing, reusing, and recycling plastic

Proxy indicators tell us of the past

-proxy indicators-indirect evidence that serve as substitutes for direct measurements of past climate -ice caps, ice sheets, and glaciers hold clues to Earth's climate history -trapped bubbles in ice cores provide a timescale of atmospheric composition, greenhouse gas concentrations, temperature, snowfall, solar activity, frequency of fires and volcanic eruptions -other indicators include: pollen preserved in sediment, tree rings, pack-rat middens, coral reefs -data from the EPICA ice core reveals changes across 800,000 years-EPICA (European Project for Ice Core in Antarctica)

A river may shift course over time

-rivers shape the landscape through which they run, carve out valleys as they change course, damming reduces river meandering -floodplain-areas nearest to the river's course that are flooded periodically, soils are fertile as a result of frequent deposition of silt, good areas for agriculture

Rising sea levels may affect hundreds of millions of people

-runoff from melting glaciers and ice cause sea levels to rise -as oceans warm, they expand-leading to beach erosion, coastal floods, intrusion of salt water into aquifers, and storm surges -storm surge-temporary, localized rise in sea level, caused by the high tides and winds of storms -cities will be flooded-53% of people in the U.S. live in coastal areas-vulnerability to storm surges will increase -rising seas eliminate marsh grasses; dams stop sediment from replenishing deltas -in 2013 Typhoon Haiyan struck the Philippines-7000 lives lost, over $1.5 billion in damage -rising seas will displace millions of people from coastal areas-many will have to invest in costly efforts to protect against high tides and storm surges -areas that will be most affected include densely populated, poor regions (e.g., Bangladesh), storm-prone regions (e.g., Florida), coastal cities (e.g., Houston), areas with land subsidence (e.g., U.S. Gulf Coast), Pacific islands will have to be evacuated-Hurricane Sandy ("Superstorm") demonstrated the impact that storm surges can have on metropolitan areas

Salt marshes line temperate shorelines

-salt marshes-occur along coasts at temperate latitude, tides wash over gently sloping, sandy, or silty substrates, tidal creeks: channels that tides flow into and out of, have salt-tolerant plants, filter pollution and stabilize shorelines -high primary productivity provides critical habitat for birds and commercial fish and shellfish species

Extreme weather is becoming "the new normal"

-scientific data summarized by the U.S. Climate Extremes Index-confirms that frequency of extreme events in U.S. has been rising since 1970 -changes in jet stream can cause extreme weather events-atmospheric blocking pattern, blocks eastward movement of weather systems

Sediment pollution

-sediment in rivers can impair aquatic ecosystems-clear-cutting, mining, clearing land for housing, and cultivating farm fields expose soil to erosion -it dramatically changes aquatic habitats-impairs organism respiration, fish may not survive, cloudy water blocks sun, killing rooted plants -solutions-adopt sustainable soil practices, avoid large-scale disturbance of vegetation, maintain riparian vegetation to trap sediments

Climate varies naturally for several reasons

-solar output-the sun varies in the radiation it emits, variation in solar energy (e.g., solar flares) has not been great enough to change Earth's temperature, radiative forcing is 0.05 watts/m2-less than any human-made causes -ocean absorption-oceans hold 50 times more carbon than the atmosphere, slows global warming but does not prevent it, as oceans warm, they absorb less CO2,accelerating warming-ocean circulation -ocean water exchanges heat with the atmosphere, currents move energy from place to place -the oceans' thermohaline circulation system affects regional climates-moves warm tropical water north, etc., Greenland's melting ice sheet will affect this flow -El Niño and La Niña events change regional weather-dry areas get wetter, while wet areas get dryer -Milankovitch cycles-periodic changes in Earth's rotation and orbit around the sun, alter the way solar radiation is distributed over Earth-these cycles modify patterns of atmospheric heating-trigger climate variation, glaciation-cold temperatures and ice sheets

Some dams are being removed

-some feel that the costs of dams outweigh their benefits-they are pushing to dismantle dams -letting rivers flow free will restore ecosystems, reestablish economically valuable fisheries, and revive river recreation (fishing, rafting) -old dams or those that are no longer economical are candidates for removal-400 dams have been removed in the United States, 500 more may be removed

Open-ocean ecosystems vary in their biodiversity

-some ocean regions support more life than others-photic zone-well-lit top layer that supports high primary productivity, warm, shallow waters of continental shelves are the most productive and support the highest biodiversity-pelagic zone-habitats and ecosystems occurring between the ocean's surface and floor-benthic zone-habitats and ecosystems occurring on the ocean floor-surface primary production and animal populations are high around nutrient-rich upwellings-phytoplankton, zooplankton, fish, jellyfish, whales, predators include larger fish, sea turtles, and sharks

Precipitation is changing, too

-some regions are receiving more rain and snow -other areas are receiving less-in the U.S. Southwest, droughts have become more frequent and severe -harm agriculture, promote soil erosion, reduce water supplies, and trigger fires -in dry, humid regions, heavy rains cause flooding-kill people, destroy homes, and inflict billions of dollars in damage, example: 2008 floods in Iowa and the Midwest -precipitation will increase at high latitudes and decrease at low and middle latitudes -worsening water shortages in poor nations

Surface water converges rivers and streams

-surface water-water on Earth's surface, comprises 1% of freshwater, is vital for our survival and ecological systems, becomes groundwater by infiltration -runoff-water that flows over land, water merges in rivers and ends up in a lake or ocean -tributary-a smaller river flowing into a larger one -watershed-the area of land drained by a river and its tributaries

Scientific evidence for climate change is extensive

-the Intergovernmental Panelon Climate Change(IPCC) was established in 1988-composed of hundreds of international scientists and government representatives, IPCC released its Fifth Assessment Report(2014), documents observed trends in surface temperature, precipitation patterns, snow and ice cover, sea levels, storm intensity, etc., predicts future changes in wildlife, ecosystems, and human societies, discusses strategies to pursue in response to climate change

Greenhouse gas concentrations are rising fast

-the greenhouse effect is natural-greenhouse gases have always been in the atmosphere -we are concerned with the anthropogenic(human-caused) intensification of the greenhouse effect -we have increased the concentration of these gases beyond what we have ever experienced- CO2has increased from 280 ppm (1700s) to 399 ppm-the highest in 800,000 (possibly 20 million) years-burning fossil fuels transfers CO2from underground deposits into the atmosphere -the main reason CO2levels have increased-deforestation contributes to rising atmospheric CO2-plants store carbon in their tissues, less CO2is absorbed from the atmosphere-methane-fossil fuels, livestock, landfills, crops (rice), levels have increased 2.6 times since 1750-nitrous oxide-feedlots, chemical manufacturing plants, auto emissions, and synthetic nitrogen fertilizers, levels have risen 20% since 1750-ozone -levels have risen 36% because of photochemical smog, the Montreal Protocol has reduced halocarbons (CFCs)-water vapor-the most abundant greenhouse gas, contributes most to the natural greenhouse effect, but concentrations have not changed

Three factors influence Earth's climate

-the sun-without it, Earth would be dark and frozen, it supplies most of Earth's energy -the atmosphere-without it,Earth's temperature would be much colder, clouds, land, ice, and water absorb 70% of incoming solar radiation, the remaining 30% is reflected back into space -the oceans-shape climate by storing and transporting heat and moisture

The Aral Sea in central Asia was once the world's fourth largest lake

-the two rivers leading into the Aral Sea were diverted to irrigate cotton fields, 60,000 fishing jobs are gone, people are trying to save its northern part

We treat our drinking water

-treatment of drinking water is widespread and successful in developed nations -before water reaches the user, it is chemically treated and then filtered and disinfected -The EPA sets standards for over 90 drinking water contaminants-local governments and private water suppliers must meet these standards -water treatment has reduced deaths from diseases-it is one of the greatest advances of modern times

Fresh water and human populations are unevenly distributed across Earth

-water is unevenly distributed in space and time-different areas possess different amounts of water, people are not distributed according to fresh water -climate change will worsen water conditions -changed precipitation patterns, melting glaciers, droughts, floods, etc.

Freshwater systems

-water may seem abundant, but drinkable water is rare -fresh water-relatively pure, with few dissolved salts, most is tied up in glaciers, ice caps, and aquifers -water is renewed and recycled by the water cycle -precipitation forms rivers, which carry water to oceans and lakes, rivers interact with ponds, wetlands, and coastal systems, groundwater exchanges water with surface sources -the water cycle creates a web of interconnected aquatic systems -exchanges water, organisms, sediment, pollutants, what happens in one system affects other systems-a web of interconnected aquatic ecosystems

Legislation and regulation have helped to reduce water pollution

-water pollution was worse decades ago-U.S. citizen activism and government response resulted in legislation during the 1960s and 1970s -The Federal Water Pollution Control Act (1972)-renamed the Clean Water Act in 1977, made it illegal to discharge pollution without a permit, set standards for industrial wastewater, funded building of sewage treatment plants-the situation is much better now -the Great Lakes are much cleaner but still have issues

Thermal pollution

-water that is too warm causes problems-warmer water holds less oxygen, cooling an industrial facility with water heats water, which heats a river when it is released, removing streamside cover raises water temperature -water that is too cold also causes problems-water at the bottom of reservoirs behind dams is colder, when water is released, downstream water temperatures drop suddenly, killing aquatic organismsWaterpollutants can contaminate groundwater -groundwater pollution is hard to detect and address-groundwater retains contaminants for decades and longer, contaminants break down more slowly because of lower levels of sunlight, microbes, and dissolved oxygen -some toxic chemicals occur naturally-Aluminum, fluoride, sulfates -pollution from human activities leaches through soils-agricultural nitrates cause "blue baby syndrome", caused by leaking underground storage tanks, improperly designed wells, and improper storage of hazardous wastes

Effects of human activities on waterways

-wateris a limited, but renewable, resource as long as we use it sustainably -people are withdrawing water at unsustainable rates -surface and groundwater are being depleted, one-third of the world's people are affected by shortages -people also engineer waterways-dams, levees, diversion canals, for supplies, transportation, and flood control, what we do in one part of the aquatic system affects other parts

Solutions to depletion of fresh water

-we can either increase supply or reduce demand-dams have increased supplies-but most major rivers have already been dammed -desalination(desalinization)-removal of salt from seawater, 20,000 facilities operating worldwide -drawbacks-is expensive, requires large inputs of fossil fuel energy, kills aquatic life at water intakes, generates concentrated salty waste -mostly found in wealthy oil-rich nations where water is extremely scarce

China's Three Gorges Dam

-world's largest dam, on the Yangtze River, provides flood control, passage for boats, electricity, $39 billion to build, flooded 22 cities, displaced 1.24 million people, submerged farmland, wildlife habitat, 10,000-year-old archaeological sites, eroding tidal marshes