Insights on Environmental Effects

Sherry Seethaler

Tempest Tech

Why can’t the wind wall of a hurricane be zapped with lasers, disrupting the airflow and degrading these destructive monsters to just simple passing storms?

The first hurricane-modification mission, Project Cirrus, in October 1947, resulted in outraged citizens and threats of legal action. The targeted hurricane, which was heading east away from the coast of Florida before intervention, turned around and pummeled the coasts of Georgia and South Carolina. From what we know now, the turn likely had nothing to do with the intervention, but the inauspicious beginning cast a pall over hurricane-modification efforts.

A couple bad hurricane years renewed interest in hurricane research and led to Project Stormfury, launched in the early 1960s. Stormfury’s goal was to study the formation, structure, and dynamics of hurricanes to improve forecasts and seek ways to modify hurricanes. Stormfury continued for 21 years, but modification attempts were conducted on only four hurricanes, in part because the region in which hurricanes could be targeted was very restricted.

Cirrus and Stormfury employed low-tech “seeding.” Seeding by dumping dry ice or silver iodide into clouds can result in rain or snow because the particles provide a surface on which cloud-borne moisture can freeze. Heat is released during freezing, and the working hypothesis was that the heat produced by seeding hurricanes would disrupt airflow in the storm system and weaken its winds.

Results consistent with the hypothesis occurred in three of the four hurricanes seeded. Unfortunately, as the researchers studied more hurricanes, they discovered that the weakening they observed in the seeded hurricanes also occurred in unseeded hurricanes. Worse, the basis of their working hypothesis turned out to be flawed. Seeding has an effect only if not enough natural ice crystals are present to act as seeds. In contrast to what the researchers initially thought, plenty of natural ice crystals are present in the hurricane updrafts and downdrafts.

Computer models show it is theoretically possible to weaken or reroute hurricanes. One suggested method is to use an array of solar power stations orbiting Earth that would produce microwave beams to heat sections of a storm to perturb it. Another idea is to cool the ocean surface or cover it with a biodegradable film to reduce evaporation, starving the storm of the energy that fuels it.

The sheer scale and immense power of hurricanes make any method a challenge, and although scientific understanding has advanced tremendously since Project Cirrus, hurricanes remain unpredictable. Political problems are a risk if the intervention fails or accidentally sends (or seems to send) the hurricane toward another country.

Eye of the Storm

Can you explain why warm water is needed to fuel a hurricane?

A skyward flow of warm, moist air is required for the initiation and continuation of the storm. Consequently, warm water, usually 80°F (27°C) or warmer, provides the energy that sustains the hurricane; hurricanes diminish in strength when they pass over cold water, churn up cold water from the ocean depths, or make landfall.

Warm, moist ocean air is forced aloft when air masses or surface winds converge. The air cools as it rises, causing the water vapor in it to condense. Condensation releases heat, which warms the air and causes it to rise further. To compensate, surrounding air flows outward at the top of the storm. The outward flow of air diminishes the amount of air in the column in which the storm is brewing, lowering the pressure at the ocean surface.

The reduction of pressure at the ocean surface increases evaporation. Therefore, a chain reaction of evaporation and condensation occurs as long as the source of warm, moist ocean air is available and no wind shear exists to break up the storm. As the chain reaction continues, the temperature increases dramatically at higher altitude in the storm’s core. At the surface, wind speed increases as more air is drawn into the low-pressure area.

The rotation of Earth creates a pattern of wind that circulates counterclockwise (in the Northern Hemisphere) around the center of the storm. This gives the hurricane its characteristic spiral shape of concentric bands of thunderstorms surrounding a central eye. The fiercest wind and rain occur just around the eye of the storm—in the eyewall—yet the eye itself remains a calm area because the winds swirl around the eye but do not extend into it.

Since Hurricane Katrina, much discussion has centered on how global warming may affect the number and intensity of hurricanes. Increased ocean surface temperatures could support more intense storms and increase the length of the hurricane season, which currently runs from June through November in the tropical North Atlantic and North Pacific oceans.

Hurricane number and intensity has increased in recent years, according to the available data, but this increase may not be “real.” Until satellite measurements began in the 1970s, hurricane data were collected with ships and airplanes, which cannot detect all storms or measure the strongest winds in the eyewall. So the apparent increase in hurricane number and intensity could be attributable to flaws in the older data.

What’s in a Name?

How are Asian cyclones named? I saw that TS 06W was followed by Typhoon Pabuk, with TS Wutip right behind.

Nearly all tropical cyclones are given people’s names. During World War II, U.S. Army and Navy meteorologists informally named storms after their girlfriends and wives. The U.S. Weather Bureau adopted the policy of giving women’s names to tropical cyclones in 1953. Later, in the interest of gender equity, men got equal opportunity to have storms named after them.

Now the United Nations’ World Meteorological Organization (WMO) names most storms. The WMO uses a predetermined list for each ocean basin. For most basins, the WMO uses yearly, alphabetical lists of names in the predominant languages of the countries in that region. For example, English, Spanish, and French names are used in the North Atlantic region, which includes the Gulf of Mexico and the Caribbean Sea.

The naming of cyclones in the Northwest Pacific follows a different pattern. Most of the names are either Asian words for plants, animals, and foods, or adjectives; just a few are personal names. In addition, the names are not listed from A to Z, but rather in order of the contributing nations, which are alphabetized. Laos contributed the name Pabuk, which is a freshwater fish. Macau contributed the name Wutip, which means butterfly.

As soon as the Joint Typhoon Warning Center in Hawaii detects a tropical depression, a rotating area of low pressure that may become a tropical storm, it assigns it two digits and a letter. The letter identifies the region; W stands for the western North Pacific. TD 06W was the sixth tropical depression (TD) in the western North Pacific that hurricane season. TD 06W did achieve tropical storm (TS) strength, defined as winds of 34 knots or more, at which point it should have been given a name. It retained tropical storm status for less than a day. It was then downgraded to a tropical depression, and it remained unnamed despite the damage it did.

Name rosters are reused, but if a storm causes significant damage and deaths, the name of the storm can be retired as an act of respect for the victims and to prevent confusion on insurance claims. Katrina, Rita, Isidore, and Juan are just a few of the many names that have been retired (see www.nhc.noaa.gov/retirednames.shtml for a full list). The country worst hit by a storm can ask the WMO’s Regional Association to retire the name from the region and can offer a replacement name.

What Causes Tornadoes to Occur?

About 800 to 1,000 tornadoes occur annually in the United States. Most occur in the center and southeast of the country, where warm, moist air from the Gulf of Mexico meets air masses from Canada or the Rocky Mountains. Tornadoes are most common in the spring and summer months, but they can happen anywhere, at any time of the year.

Tornadoes usually develop from thunderstorms. Thunderstorms result when warm, humid air rises and encounters a layer of colder air. This cools the warm air and causes the water vapor in it to condense into water droplets or freeze into ice crystals. Condensation and freezing release heat, which triggers more upward air movement and adds to the storm’s power. Tornadoes form between the rising warm air and the cooler air descending with the rain or hail.

The strongest tornadoes are produced by supercells, large thunderstorms with cloud structures 1,000 cubic miles or greater. Normal thunderstorms are stifled when falling, rain-cooled air cuts off the supply of rising, warm, humid air. In a supercell thunderstorm, a slowly rotating column of air called a mesocyclone prevents rain from falling into the rising air and allows the thunderstorm to last for hours.

A mesocyclone develops when winds at higher altitudes blow at different speeds than those at lower altitudes, which turns the air between like a rolling pin. The upward flow of warm air in the thunderstorm can tilt this rolling tube of air from horizontal to vertical, giving birth to the mesocyclone. Most strong and violent tornadoes form within the mesocyclone.

Meteorologists understand how thunderstorms and mesocyclones form. However, they cannot explain why not all thunderstorms, not even all supercells, give rise to tornadoes, or why tornadoes can be spawned by growing clouds that have not yet become thunderstorms. Preliminary evidence suggests that a fluctuating downdraft, driven by falling precipitation, may energize a tornado. The downdraft draws rotation downward and focuses it.

A series of aptly named projects have sought to determine the exact mechanism that produces the rapid twisting of the tornado itself: Verification of the Origins of Rotation in Tornadoes EXperiment (VORTEX); Radar Observations of Tornadoes And Thunderstorms Experiment (ROTATE); and the TOtable Tornado Observatory (TOTO), the real-life inspiration for the Dorothy device in the movie Twister.

TOTO never actually saw the inside of a tornado, but recently, armored probes called “turtles” have successfully measured pressure, temperature, and humidity beneath tornadoes. In addition, mobile Doppler radars are providing enhanced details of tornado features and wind speeds. With these measurements and computer modeling, researchers hope to turn out a much less cloudy picture of tornado formation.

Rain Terrain

Why is the western half of the Unites States mainly desert, whereas the eastern half is green from much more rain? Texas is actually split down the middle—desert and green.

Across the United States, average precipitation is high in the East and Northwest, moderate in the middle of the continent and very low in the Southwest. Geographic precipitation patterns depend on proximity to water, local topography, distribution of air masses, and global pressure systems.

The Pacific Northwest’s famously wet weather is due to the prevailing winds forcing moist maritime air masses to undergo orographic uplift, rise up a mountain slope. As the rising air masses cool, the moisture in them condenses and drops on the windward side of the Rocky Mountains. After the air masses pass over a mountain, they descend and warm, creating a rain shadow on the mountain’s lee side.

Because the Rockies run from north to south along the western part of North America, perpendicular to the prevailing winds, the central part of the continent is relatively dry. In contrast, in Europe, maritime air masses can penetrate deeper into the continent because the major mountain chains are oriented east–west, parallel to the prevailing winds.

The U.S. Southwest is dry for the same reason a belt of deserts circles the globe at approximately the same latitude, near 30° north and south. These deserts include the Mojave, Sonoran, Sahara, and Arabian deserts in the Northern Hemisphere, and the Atacama, Kalahari, and Australian deserts in the Southern Hemisphere.

These deserts coincide with high-pressure systems—the subtropical highs—caused by sinking air masses that are part of global air circulation patterns. Hot air rises at the equator and sinks at higher latitudes. Subsiding air inhibits precipitation as it warms and evaporates moisture and by suppressing uplift of other air masses in the region.

The subtropical high shifts poleward as the sun’s elevation increases in the spring and equator-ward as the sun’s elevation declines in the fall. The north–south shift brings dry summers and rainy winters to regions on the poleward edge of the subtropical high.

In the Southeast, air masses passing over warm Gulf Stream currents provide a source of moisture when they blow onshore. Uplift induces precipitation as these air masses pass onto land. Precipitation also occurs across the eastern half of the United States as these warmer air masses move inland and clash with polar air masses from Canada.

Blowin’ in the Wind

Earth rotates at about 1,000 miles per hour eastward. Therefore, one would think that the jet stream would blow from east to west. However, it doesn’t. Why this contradiction?

The atmosphere rotates along with Earth; therefore, the jet stream is not analogous to the wind in your face as you speed along on a bike or in a convertible. If it were, the jet steam would be strongest at the equator, where Earth’s surface is farthest from the rotation axis and spins the fastest. In reality, early mariners dubbed the equatorial region “the doldrums” because it lacks prevailing winds.

Jet streams are generated by differential heating of Earth’s surface. Because of the tilt of the Earth, higher latitudes receive less solar radiation than the tropics. The distribution of solar energy received by each hemisphere changes from summer to winter, altering the strength and locations of the jet streams. The gradient of incoming solar energy creates pressure gradient forces and sets up a north–south conveyor belt of air masses.

Air near the equator rises as it warms, creating a region of low pressure. The warm air from the equatorial region flows at high altitudes toward the poles. Partway there, the air cools and descends. From this high-pressure zone, air flows to the low-pressure zone at the equator, completing the north–south loop.

This large-scale overturning of the atmosphere is called the Hadley Circulation. In both hemispheres, two additional smaller circulation loops exist between the Hadley Circulation and the poles. The temperature gradient between the equator and the poles is not even. The jet streams, which are typically eastward-flowing rivers of wind miles above Earth’s surface, form along boundaries between air masses with the greatest temperature contrast.

The Coriolis effect, an indirect effect of Earth’s rotation, causes these winds to flow west to east. An air mass rising over the equator has the same west-to-east motion as the ground beneath it. As the air mass moves northward, it still has the same west-to-east motion, but as a result (because Earth’s surface spins faster at the equator), the air mass is moving more quickly eastward than the ground beneath it.

In contrast, an air mass flowing from higher latitudes to the equator has less eastward motion than the ground beneath it, so near the tropics, the winds tend to blow toward the west. Sailors have long taken advantage of prevailing wind patterns by sailing close to the equator (while avoiding the doldrums) to get from Europe to the Americas and taking a more northern route to return home.

It is generally believed that naturally occurring vortexes tend to rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. I heard someone say with absolute certainty that this directional phenomenon also applies to the swirl that occurs in the bowl when a toilet is flushed. My position is that the direction of swirl depends solely on the design of the toilet, not the hemisphere in which it is located. What are your thoughts in this regard?

Anyone who has traveled across the equator has probably been asked to report back on toilet swirl. On my own trip to the Land Down Under, I was (nerd alert!) so intrigued by the light flush/heavy flush options on many of the toilets (a water conservation measure for a dry continent) that I forgot to study direction of swirl.

Not that it matters. The direction in which water is injected into the bowl through angled tubes determines which way your business spins. That the direction toilets flush or drains drain depends on hemisphere is a myth perpetuated in popular culture, including a Simpsons episode, “Bart Versus Australia,” as well as some (usually) more scholarly sources.

Like many myths, it is based on the misapplication of a real phenomenon—in this case, the Coriolis effect. It was well known by the 1800s that cannonballs fired along a north–south line in the Northern Hemisphere tended to land to the right of their direction of travel. This apparent deflection is caused by the Coriolis effect, the rotation of Earth beneath the cannonball.

The eastward speed of an object on Earth is lower at higher latitudes. At the North Pole, it would have no eastward movement; it would simply spin around once per day. At the equator, an object travels in a circle the circumference of the Earth, moving eastward at more than 1,000 miles per hour. Therefore, a cannonball fired northward in the Northern Hemisphere has a greater eastward speed than the ground beneath it. It lands to the east (right) of where it would if Earth was stationary.

The Coriolis effect is responsible for the large-scale dynamics of the atmosphere and oceans. For example, in the Northern Hemisphere, it causes air to move clockwise around a high-pressure area and counterclockwise around a low-pressure area, as in the case of a hurricane. The motion is the mirror image in the Southern Hemisphere.

Nevertheless, just as one does not worry about the Coriolis effect when playing ball in the backyard, the effect is negligible on the small scale of toilets and sinks. The direction in which water was initially added and the geometry of the sink or toilet determines how it drains.

Be Still, Rubber Ducky

Isn’t standing water in a perfectly level and symmetrical basin actually slowly turning counterclockwise (in the Northern Hemisphere) due to Earth’s rotation? When the water is allowed to drain, the progressively smaller radius required for the water to flow through the drain opening requires that it increase in velocity to maintain angular momentum (think of a spinning ice skater pulling in his arms). Hence, the slow, imperceptible counterclockwise rotation of the standing water becomes much more pronounced as the water leaves the basin.

If no other torques—twisting forces—are acting, one can see the effect of Earth’s rotation on the direction of swirl in a draining bathtub. Ay, there’s the rub. Residual motions from filling or splashing in the tub, air currents in the room, thermal currents due to nonuniform water temperature, the act of pulling the plug, and any lack of symmetry of the vessel outweigh the Coriolis effect. For example, by varying how the kitchen faucet is positioned as the sink is filled, it is possible to switch the draining vortex from counterclockwise to clockwise.

For a small tub, the Coriolis acceleration is at least 100,000 times smaller than the acceleration due to gravity. Therefore, to detect the Coriolis effect on a draining tub, one must be very, very patient. Well-controlled conditions are also essential, including the use of a symmetrical tub to minimize torques produced by the tub’s walls, a plastic cover to eliminate the effect of air currents, a room maintained at uniform temperature to reduce thermal currents, and the ability to remove the drain plug from below.

Fortunately, a Boston-based scientist by the name of Ascher Shapiro had the patience and equipment and published his results in Nature in 1962. He discovered that if the water in a covered tub was left to settle for 24 hours, the residual motions were eliminated. When the plug was carefully removed, the vortex was invariably counterclockwise even if the water was initially added with a clockwise spin. Therefore, under tightly controlled conditions, drain swirl is consistent with the Coriolis effect, but in everyday situations, the Coriolis effect is too small to influence rubber ducky’s trajectory in the tub.

Parched

News reports frequently blame the Southwest’s diminishing water supply on a continuing drought. Are the news reports misidentifying an oversubscription (human demand) of Western water resources or has there really been a significant change in precipitation in the Southwest? Or are both causes contributing simultaneously?

The drought is real but not unusual. The two relatively wet decades that preceded it were more of an anomaly. A wealth of data about past climate, including lake sediments and annual growth rings of trees, reveal that periodic droughts are a normal occurrence in the Southwestern United States.

The last major drought in the region occurred during the 1950s. The recent drought has been warmer than the 1950s drought and has resulted in more extensive tree die-offs. The die-offs are not constrained to places where humans are competing with the trees for ground or surface water. Compared to a drought that occurred in medieval times, however, the current drought is mild. A.D. 900 to 1400 was a period of successive droughts, each tending to persist for decades, compared to the multiyear or decade-long droughts of modern times.

Today the demand of the colossal urban and agricultural infrastructure in the ever-growing Southwest far outstrips the water supply. In many places, groundwater extraction has dramatically lowered the water table. This has destroyed vegetation, resulted in subsidence—lowering of the ground surface—and caused sea water to intrude into coastal aquifers.

Surface waters are also receding all over the thirsty Southwest. Without a decrease in water use, the Lake Powell and Lake Mead reservoirs on the Colorado River likely will be completely depleted by 2021, according to a Scripps Institution of Oceanography study. The Colorado River is oversubscribed because the water rights documents that determine the water allocations to the states of the Southwest were drawn up in the early 1900s, during a period of exceptionally high stream flow.

Droughts in the Southwest are associated with periodic variations in sea surface temperatures linked to changes in ocean circulation. Most familiar, La Niña conditions—cooling in the equatorial Pacific (the opposite of El Niño)—lead to the formation of an atmospheric ridge that keeps precipitation off the Southwest. Climate in the Southwest is also influenced by periodic sea surface temperature changes farther north in the Pacific and the North Atlantic.

Or Deluged?

Some scientists believe Southern California will experience diminishing rainfall in the future due to global warming. I have also read that climate change will likely result in a “perennial El Niño effect” in the Pacific. Because El Niños generally increase California’s rainfall, these two predictions appear to conflict. What’s the real answer?

Initially, global warming was predicted to lead to more and stronger El Niños by affecting the sea surface temperature gradient that drives the El Niño–Southern Oscillation (ENSO), the planet’s most prominent year-to-year climate variation. The most recent evidence suggests that a change in the ENSO is unlikely.

In a non–El Niño year, the tropical Pacific is 3°F to 6°F (5°C to 10°C) warmer in the west than in the east. The warmer water in the west heats air masses and causes them to rise, generating strong rainfall in the area. The air masses then flow eastward, in the direction of the prevailing winds, and descend over the cooler water.

The result is a conveyor belt–like movement of air, the Walker circulation. Strong westward surface winds complete the circulation. The winds pile up warm water in the western equatorial Pacific and stimulate the upwelling of cold water from beneath the surface in the east. Therefore, the winds and sea surface temperature gradient reinforce each other through positive feedback.

During an El Niño event, there is a breach in the positive feedback. The sea surface temperature gradient declines as the water in the east warms. Global precipitation and climate patterns are impacted, including increased winter storms across the Southern United States.

Consistent with global warming, tropical Pacific sea surface temperatures have increased during the past half-century. The warming is asymmetrical and initially appeared to be occurring in an El Niño–like pattern.

A closer analysis, described in a December 8, 2009, study published in the journal Proceedings of the National Academy of Sciences, revealed that the latitude and extent of the warming differs from the canonical El Niño pattern. Furthermore, a comparison of 20 climate models revealed that El Niño frequency likely will remain the same during the next century.

ENSO is not the only way global warming can alter precipitation patterns. Warming also increases the amount of water vapor in the atmosphere. Instead of the increased water vapor leading to uniform increases in precipitation, a “rich-get-richer” scenario appears more likely. Regions that already receive high rainfall because of local geo-graphy and air currents will likely get wetter, while drought-prone areas such as Southern California will get drier.

Fast Fashion

How do we go about recycling old sheets, clothing that is no longer wearable, and towels? I cannot bear to throw them in the landfill, and I have enough rags to last the rest of my lifetime.

Americans generate more than 12 million tons of waste textiles annually, constituting 5 percent of total municipal solid waste, according to the U.S. Environmental Protection Agency. This textile waste, which is from industry and domestic sources, is equivalent to approximately 80 pounds per person. As globalization has made it possible to create clothing at increasingly lower prices, textile waste has increased, with implications that go beyond disposal. For example, a quarter of pesticides used in the United States are applied to cotton crops.

Fortunately, recycling of textiles is on the rise. Textile recyclers separate used clothing into categories according to type, size, and fiber content. Over half of the recycled clothes are turned into rags and absorbent pads for industrial spills or are recycled into fiber. Polyester is processed using heat, and cotton is garneted, a mechanical process that turns it back into fiber. The fibers are then used to make paper, stuffing for furniture, or insulation.

The remaining clothing is exported. The Salvation Army estimates that when clothing is disposed of, it has at least 70 percent of its useful life left. Japan is the largest buyer of high-end or vintage American fashion. Cheaper clothing is packaged into 100-pound bales and shipped to developing nations. Small entrepreneurs buy the bales and sell the clothing at markets.

Reuse or recycling of textiles results in considerable energy savings. For every pound of virgin cotton that is displaced by secondhand clothing, 30 kilowatt-hours (kWh) is saved, and for every pound of polyester, 40kWh is saved, when resource extraction, manufacturing, collection, distribution, and waste disposal are taken into account, according to a life cycle assessment published in the January 2006 issue of the journal Resources, Conservation and Recycling.

Textile recyclers do not usually obtain clothes directly from consumers. Instead, castoffs can be donated to charitable organizations, such as the Salvation Army, Goodwill, or St. Vincent de Paul. Those organizations sell items they cannot use or sell in thrift shops to textile recyclers for a few cents per pound. Other potential uses for old sheets, towels, and other fabrics include packaging materials, arts and crafts, or drop cloths for painting.

Items made from fur can be recycled into new animals (well, kind of) through the Coats for Cubs program run by the Humane Society of the United States (HSUS). HSUS distributes the furs to more than 200 wildlife rehabilitators across North America. Rehabilitators report that the fur “surrogate mothers” reduce stress in their injured and orphaned wildlife patients. For more information, see www.hsus.org/furdonation.

Trash or Treasure?

I have heard from a couple different sources that, with the exception of aluminum cans, recycling is actually bad for the environment because the resources expended in recycling are higher than those saved. What is the truth behind this concept?

An accurate assessment of the environmental soundness of recycling must consider the energy required to process virgin materials versus reprocess recyclables, the air and water pollution and solid waste produced in each case, the environmental costs of placing recyclables in landfill, and the environmental costs of acquiring virgin materials. Studies suggesting that recycling is bad for the environment ignore part of the picture.

• Aluminum—The efficiency of recycling varies for different types of materials. Recycling aluminum is both economically and environmentally advantageous. According to the Environmental Protection Agency, making a can from recycled aluminum takes 95 percent less energy than making one from virgin bauxite ore. Aluminum can be recycled repeatedly, keeping it out of landfills and reducing environmentally damaging mining operations.

• Paper—Recycling paper requires more water than producing paper from wood, but recycling releases fewer toxic chemicals.

Recycling paper reportedly uses more fossil fuels, but the data are misleading because the forest products industry generally does not factor in fuel used in forest management (drilling, seeding, harvesting). Furthermore, decomposition of paper in landfill produces methane, a greenhouse gas.

Some argue that because trees are replanted, harvesting wood has no environmental impact. Not true. Old-growth forests, which are cut down to make way for tree plantations, have more species of trees at mixed ages and heights, and they contain more animal habitats and, consequently, more biodiversity. Therefore, overall, recycling paper benefits the environment.

• Plastic—Melting plastic to reuse in containers, plastic lumber, and so on is environmentally sensible because plastic is derived from crude oil. Unfortunately, the wide variety of plastics, additives, and dyes makes separation arduous and expensive. Currently, more than three-quarters of all post-consumer plastics end up in landfills. Efforts are underway to create practical alternatives, such as gasifying plastic—turning it into fuel—to eliminate this waste.

• Glass—When glass is made from scratch (quartz sand, soda ash, limestone, and minerals), very high temperatures are required to melt the ingredients. Recycled crushed glass melts at a lower temperature, so less energy input is required when it is added to the raw materials. One complication is that window panes, light bulbs, and cookware contain ceramics and can introduce impurities. Colored glass also needs to be kept separate. Even when segregation is impractical, crushed glass is useful for drainage and building materials.

BYO Bag

Which is better for the environment, paper or plastic?

Bans on the use of plastic bags give the impression that paper
must be the better alternative. However, if they were recycled (unfortunately, a huge if), plastic bags would be more environmentally friendly than paper.

Less energy is required to make plastic bags, even factoring in that a paper bag usually gets packed with twice as many groceries as a plastic bag. Making plastic bags contributes less air pollution and waterborne waste than making paper bags. It is a disadvantage that plastic is not biodegradable, but excavations of old garbage have shown that paper also decomposes very little under the relatively dry conditions of most landfills.

The energy used to produce other plastic items, including disposable cups and plates and packaging materials, is less than the energy required to make the paper alternatives. Plastic products are lighter weight and less bulky than the comparable paper products, making them easier and cheaper to ship. The energy savings have improved over the years because the plastics industry has been “light-weighting”
objects—using less material to make products that serve the same function.

Sadly, a serious environmental problem is associated with plastic. Plastic debris is known to harm large numbers of marine animals, including whales, dolphins, seals, fish, birds, and turtles, which get tangled in it or eat it. Animals often selectively consume plastic items that resemble their natural prey, and the plastic can accumulate and block the digestive system. The plastic is released back into the environment when the animal dies and decomposes.

Enormous trash-filled gyres—areas with heavy currents that form giant whirlpools—are scattered around the world’s oceans. Because it is lightweight, slow to degrade, and omnipresent, plastic is the most common refuse in these garbage gyres. The confetti-like particles that plastic eventually degrades into over time are pervasive in the environment. Therefore, if plastic is not properly recycled, it is more environmentally harmful than paper.

For environmentally conscientious consumers anywhere, carrying reusable bags is the best solution to save resources and reduce waste. Selecting alternatives with less packaging and buying in bulk when practical also helps the environment. The largest portion of municipal waste is packaging and containers, comprising nearly one-third of total waste generated.

Americans generate about 250 million tons of solid waste annually (not including construction or industrial waste), according to the U.S. Environmental Protection Agency. That is an average of 4.5 pounds per person per day. Paper and cardboard make up 34 percent of the waste by mass, but half is recycled. Plastic accounts for 12 percent, and only a small fraction is recycled.

Trash Tour

Here’s a question that perplexes me every time I throw a tissue in the toilet or push vegetables down my garbage disposal. If organic matter or paper cannot be recycled, which method of disposal is the most environmentally friendly? Should we try to put as much as possible into the city sewer system and hope that the sludge it becomes will be used somehow? Or is it best to flush as little as possible and send everything off to be locked up in a landfill?

A general rule of thumb is that if it makes you send more water down the drain or toilet, it is not helping the environment.

Although rarely discussed in polite company, flushing accounts for more than a quarter of indoor water usage. Older toilets use up to seven gallons per flush. In 1994, a federal law created a new standard of 1.6 gallons per flush. The latest trend is dual-flush models that use 0.8 gallons of water to dispose of liquid waste and twice that for solids. Well over one-third of American homes have pre-1994 toilets.

Whether one’s abode is equipped with a water-gobbling monster or an eco-throne, if it is hooked up to the city sewer system, whatever gets flushed goes to a sewage treatment plant. There, screens are used to remove toys, rags, and other large items that were inadvertently or deliberately flushed down the toilet or sent down the drain. This material is sent to landfills. Sand grit and stones are allowed to settle out and are also usually sent to landfills.

The remaining liquids and solids are separated by sedimentation. The liquid is treated with bacteria that break down the biological compounds, including those from food waste, human waste, soap, and detergent. Before the liquid is released back into rivers or lakes or recycled for irrigation, it is filtered and disinfected with chemicals or with ultraviolet light.

The sludge is also usually processed with bacteria and then treated with chemicals. The U.S. Environmental Protection Agency estimates that about half the treated sludge, referred to as biosolids, is recycled to land as fertilizer. Otherwise, it ends up in landfills, sometimes as daily landfill cover.

Given that a lot of what goes down the pipes ends up in landfills after much processing, it is better to send garbage to landfills directly if it cannot be recycled, reused, or composted. Food composting is an educational family activity suitable for urban dwellers. Much food waste can be composted by red wriggler worms in a small bin.