ENVIRONMENT GLOBAL WARMING

Examples of Terrestrial Animals

What are terrestrial organisms? What are some examples of them?

Terrestrial Organisms

Climate Models

Terrestrial organisms

Warmer temperatures have increased growing seasons, with spring arriving earlier and fall coming later for many species of land plants and animals. The second half of the twentieth century saw an increase in growing season of up to two weeks in the mid and high latitudes, with many more frost-free days. The length of a growing season at a single research station in Spain increased by 32 days between 1952 and 2000, and the average increase across Europe was from 1.1 to 4.9 days per decade. Longer growing seasons and warmer temperatures are sometimes accompanied by higher productivity, range changes, and earlier spring and summer seasonal events.

The total effect of growing season length on productivity is unclear. Satellite data show that a lengthened growing season caused increased productivity in the Northern Hemisphere from 1982 to 1991. However, from 1991 to 2002, productivity decreased there, possibly due to hotter, drier summers and more widespread droughts.

Coral Reefs

Coral reefs are known as the “rain forests of the sea” because they harbor such an incredible abundance and diversity of life. These spectacular and beautiful ecosystems are home to more than one-fourth of all marine plant and animal species. Reefs are built of tiny coral animals called polyps that construct calcium carbonate (CaCO3) shells around their bodies. When the larva from a young coral polyp attaches itself to a good spot, usually on an existing coral, and builds a shell, the reef grows. The coral polyps enjoy a mutually beneficial relationship with minute algae called zooxanthellae. In this relationship, the photosynthetic algae supply oxygen and food to the corals, and the corals provide a home and nutrients (their wastes) for the zooxanthellae. The algae give the coral their bright colors of pink, yellow, blue, purple, and green. Coral polyps sometimes feed by capturing and eating the plankton that drift into their tentacles.

Corals can thrive only in a narrow set of conditions. They are very temperature sensitive, so the water must be warm, but not too hot. Water depth must be fairly shallow, with moderately high but constant salinity. The zooxanthellae must have clear, well-­ lit water to photosynthesize. Coral reefs protect shorelines from erosion and provide breeding, feeding, and nursery areas for commercially valuable fish and shellfish.

Damaged coral reefs sometimes turn white, a phenomenon called coral bleaching. First recognized in 1983, coral bleaching has become quite common. When coral animals are stressed, they expel their zooxanthellae. Since these algae give the coral its color, only the white limestone is left when they are gone. Sometimes zooxanthellae move back in when conditions improve, but if they are gone for too long, the corals starve and the reef dies. Coral reefs may recover from one bleaching event, but multiple events can kill them. Disease in corals and some other reef organisms has increased, especially in reefs that are already stressed.

Dr. Clive Wilkinson, coordinator of the Global Coral Reef Monitoring Network, blames the current upsurge in coral bleaching on rising seawater temperatures due to global warming. An increase in summer maximum temperatures of 1.8°F (1°C) for two to three days can trigger a coral bleaching event. If the elevated temperatures persist for less than one month, the reef will likely recover, but sustained heat will cause irreversible damage. After some high temperature episodes, the resident zooxanthellae have been replaced by a more heat tolerant species, and so the reef survives. However, many reefs are already found in the warmest water that zooxanthellae can tolerate, so this process is unlikely to save many reefs in the According to Wilkinson’s report, Status of Coral Reefs of the World: 2004, 20% of coral reefs are severely damaged and unlikely to recover, and another 24% are at imminent risk of collapse.

A wide variety of plants and animals have undergone recent range changes due to rising temperatures. An analysis of more than 1,700 species by Camille Parmesan of the University of Texas, Austin, and Gary Yohe of the University of Middletown, Connecticut, published in Nature in 2003, concluded that there has been a northward range shift of 3.8 miles (6.1 km) per decade. In tundra communities, a shift toward the poles or up mountains may result in a small decrease in range or replacement by trees and small shrubs. North American animals with ranges that are shifting northward include pikas (Ochotona sp.), Rufous hummingbirds (Selasphorus rufus), sea stars (of the class Asteroidea), and red foxes (Vulpes vulpes). Species of plants and animals that have never before been seen in the Arctic are moving in, such as mosquitoes and the American robin (Turdus migratorius). Antarctic plants have increased in abundance and range in the past few decades. Species are disappearing in the lower latitude portions of their ranges. In North America, the Edith’s checker spot butterfly (Euphydryas editha) is almost extinct in Mexico but thriving in Canada. Adélie penguins are now thriving at their southernmost locations but have experienced large population declines where they are found farthest north on the Antarctic Peninsula.

Organisms are also moving up in altitude. Besides contracting in the southern end of their range, many more populations of Edith’s checkers pot butterfly are becoming extinct in the lower elevation portions of their range (40%) than in the highest portions of their range (less than 15%). As a result, the mean elevation of the butterfly has moved upwards by 344 feet (105 m). In the Great Basin of the United States, the lower elevation populations of pika (Ochotona princeps) that were documented in the 1930s were extinct by the early 2000s because the animals have been found to die when the temperature reaches 88°F (31°C) for more than one half hour. In the Alps, native plant species have been driven off mountaintops as they search for favorable conditions and as nonnative plant species move uphill. Migrating animals are changing their ranges. Increasing numbers of European blackcap warblers (Syliva atricapilla) that have traditionally wintered in Africa are now migrating west to Great Britain. Chiffchaffs (Phylloscopus collybita) no longer migrate south, but remain in the United Kingdom for the winter. Of the 57 species of European butterflies Parmesan studied, the ranges of 35 of them were migrating northward: For example, the Apollo (Parnassius apollo), moved 125 miles in 20 years. The Purple Emperor (Apatura iris), unknown in Sweden until the early 1990s, has been increasing its population there. African species, such as the Plain Tiger (Danaus chrysippus), have moved into Spain.

In some species, life cycle events that are tied to day length or temperature are now occurring at different times. The springtime emergence of insects, egg laying in birds, and mating in all animal types is events that have advanced to earlier in the spring. Parmesan and Yoye detected an advancement of spring events of 2.3 days per decade averaged for all species and 5.1 days per decade averaged only for species that showed a change. These changes have been seen in plants, such as lupines (Lupinus sp.); insects, such as crickets and aphids; amphibians; and birds. For example, frogs in eastern North America and in England have been found to breed weeks earlier than they did early in the twentieth century. In mammals, high latitude and altitude species show the most changes. For example, yellow-bellied marmots (Marmota flaviventris) in the Rocky Mountains emerged from their winter hibernation 23 days earlier from 1975 to 1999.

Phenology is relatively easy to study in birds because the animals are visible, and their life cycles are highly regulated by seasonal changes. In many species, temperatures and conditions on the wintering grounds determine spring migration dates. British observers have noted that migratory birds now arrive in their breeding grounds 2 to 3 weeks earlier than they did 30 years ago. The egg laying dates of these birds have also advanced-an average of 8.8 days for 20 species between 1971 and 1995.

In some European flycatchers, the egg laying dates match trends in local temperature. For each 3.6°F (2°C) rise in temperature, the birds lay their eggs two days earlier. Unfortunately, the life cycles of the plants and invertebrates that these birds rely on for food have advanced even more, by about six days for each 3.6°F (2°C) rise in temperature. This timing discrepancy may, at some point, cause problems for the birds because their young will hatch well after their food sources peak. Already in some species, such as pied flycatchers (Ficedula hypoleuca), the number of young birds that hatch each year is smaller.

In some vulnerable locations, changing temperatures have led to the loss of suitable habitats, which is having a dramatic impact on some species. (A habitat is the natural environment of an organism, including the climate, resource availability, feeding interactions, and other features.) The loss of arctic sea ice, for example, is destroying the habitat that is needed by polar bears and northern seals. In the southern edge of their range, where ice is melting and hunting time is reduced, polar bear populations are in significant declines, and their mean body weight is decreasing. In addition, warmer temperatures have caused the populations of ringed seals, the bears’ main food, to decline. In the northern portions of their range, significant numbers of polar bears have drowned because they are unable to swim the greater distances between ice floes. These more northerly polar bears are also experiencing lower reproductive success and lower body weight. The direct effects of temperature changes affect animals differently. Populations of some birds increase when temperatures are high. But, as scientists have learned from El Niño events, when eastern Pacific Ocean temperatures are high, whales have less reproductive success. Some species experience mixed effects: Emperor penguins have greater hatching success when water temperatures rise, but the birds must swim farther from shore to feed, which puts a great strain on them. Also, the instability of ice shelves has reduced nesting success. These competing forces have resulted in a 70% decrease in emperor penguin populations since the 1960s.

Climate Science: What You Need To Know

CLIMATE CHANGE

The time of global warming as a controversy is over. Nearly all of the skeptics have come around. Thousands of scientists have gathered and analyzed trillions of bit soft data and constructed sophisticated climate models using the world’s most powerful computers. They have used those models to explain the environmental changes that are now being observed. And they have arrived data consensus. The data, the models, the observations, and the anecdotes all point in the same direction:

Earth is warming, and human activities are largely to blame.

Scientists mostly agree on this point, too:

People must take action on climate change, and they must do it now.

Unfortunately, society has not kept up with the scientists.

News reporters still seek out the few remaining skeptics to provide“balance “to their readers, despite the fact that these doubters have largely been discredited. Political leaders see no advantage in recognizing climate change because it is not relevant on the Short time frame of an electoral cycle.

People are happy to fall back on ideas such as “Well, Earth has been warmer in the past” without knowing what that really means and what the consequences really are. Therefore, while the problem of climate change is moving to the forefront of public consciousness, little organized action has been taken. Ultimately, climate change cannot be ignored. In human history, people have thrived when the weather was good and suffered and died when conditions were too dry, too cold, too hot, or too wet. The Vikings prospered on Greenland during the Medieval Warm Period, while at the same time the Maya civilization was collapsing due to a tremendous drought. But the good times did not last for the Vikings once the Little Ice Age arrived and wiped them out of their northern colonies. Cycles of floods and drought have initiated the spread of disease; the demise of past populations due to bubonic plague provides a chilling example.

Today, people may think that they are above the perils posed by global warming, but they are not. Small increases in temperature may benefit some crops in some regions, but that will not be true in other regions. Larger increases in temperature will hurt agriculture almost worldwide. Storms will increase in frequency and intensity, and sea level will rise, causing tens or hundreds of millions of people to become climate refugees. Vulnerable ecosystems-polar, alpine, and coral reef, to name a few-will disappear, as will the many species that will be unable to escape from, or adapt to, the new conditions. It is very unlikely that human society will be able to maintain its population and its lifestyle under these very different circumstances. But these changes are not yet inevitable.

Climate change is a more difficult environmental problem to understand and to fix than most. When a stream of toxic chemicals flows into a river, fish die. A coal-fired power plant visibly pollutes the air, and trees downwind are harmed by acid rain. These problems are visible and their effects immediate. But the buildup of greenhouse gases in the atmosphere cannot be seen and has no immediate consequences. No single event, even one as destructive as Hurricane Katrina, can unequivocally be attributed to it.

Nonetheless, there is a precedent for dealing with a similar environmental problem-a problem caused by substances that do not outwardly appear to be harmful, that bring about consequences that cannot be seen, and that are international in their effect. The problem was ozone depletion, and the cause was the chlorofluorocarbons and other man-made chemicals that caused it. When atmospheric scientists became convinced that these chemicals were causing the Antarctic ozone hole, the international community responded by phasing out and ultimately eliminating the production of ozone-destroying chemicals. As a result, the rate of increase in the size of the ozone  hole is decreasing, and the hole is likely to start healing by the end of this decade.

Solving the climate change problem will take much more effort and sacrifice than solving the relatively simple problem of ozone depletion. After all, the world economy is built on fossil fuel burning, and many portions of the economy benefit from the destruction of the

rain forests. To start dealing with the effects of climate change, climate scientists recommend that society first work toward becoming more energy efficient, and then work toward converting entirely to energy sources that produce zero carbon emissions. They also recommend reductions in the emissions of other greenhouse gases: For example, changing farming practices to reduce methane emissions and stopping the production of man-made chemicals that contribute to greenhouse warming. Finally, they recommend researching and developing more technologically advanced solutions, such as sequestering carbon and harnessing solar energy in space. The important thing is to start making these changes soon, before the temperature rise to which we are committed becomes dangerous. So far, it has been easy to ignore the environmental effects of climate change, in part because no single incident can be attributed to global warming and because the most serious consequences will not occur until the future. It is easier to deny the contributions people are making to global warming than to recognize and deal with them and make the sacrifices that this will require. The people now in power and those who are now producing most of the greenhouse gas emissions are not the ones who will suffer most of the consequences. The ones who will be most affected by global warming are the young people of today and those yet to be born.

As NASA’s James Hansen said in The New York Review of Books in July 2006, “Who will pay for the tragic effects of a warming climate?

Not the political leaders and business executives I have mentioned. If we pass the crucial point and tragedies caused by climate change begin to unfold, history will judge harshly the scientists, reporters, special interests, and politicians who failed to protect the planet. But our children will pay the consequences.” Because the consequences of global warming will largely be felt by young people, it is especially important for young people to become educated in climate change science and to learn what to do to mitigate climate changes and adapt to them. Young people can voice their dissatisfaction with the political status quo and work to help turn the situation around. It is not too late to begin.

Hurricane Katrina (2005)

Hurricane Katrina: Facts, Damage & Aftermath

Step Three: Research and Possibly Develop Some Far-out Ideas

Another idea for reducing rising temperatures is to lessen the amount of incoming solar radiation to reduce the amount of energy that enters the Earth system. There are many possible technologies for accomplishing this, and all would require a great deal of research and development to become usable. One crude idea is to enhance global dimming by purposely placing sulfate aerosols in the upper atmosphere. This strategy has a lot of trade-offs, including increased acid rain and negative health effects from pollution, although it would very likely reduce global warming. Incoming solar radiation could also be decreased by increasing cloud cover through cloud seeding.

A more technological solution is to shadow the planet with large orbiting objects. A 1,243­mile­diameter (2,000-km-) glass mirror manufactured from lunar rock, for example, could act as a sort of sunspot. As it orbited Earth, it would reflect back about 2% of incoming solar radiation to compensate approximately for the amount of heating expected from CO2 doubling. Creating such an object, however, would use a lot of energy.

Tapping into enormous amounts of energy without producing any greenhouse gas emissions is another category of technological solution to global warming. One idea is to place giant photovoltaic arrays on the Moon or in an orbit around Earth. The system would convert solar energy into microwaves and beam the energy to receivers on Earth.

A solar plant outside of Earth’s atmosphere would receive eight times more solar energy than one inside the atmosphere due to the lack of gases, clouds, or dust to block the sunlight. While these panels would be tremendously expensive, the technology could be extremely effective later this century.

For complex technical solutions to be successful in reducing global warming, at least four things are necessary:

The technology must work.

The negative consequences (e.g., environmental damage) of the technology must be minimal.

The technology must be effective enough to combat the effects of continual increases in greenhouse gas levels.

The technology must be less expensive than the cost of reducing emissions at the source.

Individual Contributions

While avoiding dangerous climate change will require coordinated efforts on a global scale, individuals can make a difference by being conscious of what they do, what they buy, and what actions they take. People in the developed world lead energy-intensive lives. Energy is used to power up computers, cook meals, drive to soccer practice, and manufacture consumer goods. Reducing energy consumption reduces greenhouse gas emissions. Limiting the consumption of consumer goods, seeking out more energy-efficient technologies, and avoiding activities that use excessive energy are all steps that individuals can take to reduce their impact. Governments can also assist individuals in being more energy efficient by providing monetary incentives for energy conservation.

Energy-Saving Behaviors

Small actions can lead to big energy savings when a large number of people engage in them. A few guidelines for saving energy are:

Turn electrical appliances off when they are not in use, including lights, televisions, and computers.

Unplug cell phones and other chargers when not in use.

Use precise task lighting at night.

Change old light bulbs to compact fluorescents.

Keep the thermostat set to a reasonable temperature.

Always be conscious of ways to reduce energy consumption.

For example, take showers instead of baths, and only boil the amount of water needed for cooking.

Because most energy consumption is involved with transportation, and because every gallon of gasoline burned emits 20 pounds (9 kg) of CO2 (and many other pollutants), conserving energy in transportation is extremely important. If possible, drive less by living near work or school or by using public transportation. Walking, riding a bike, and carpooling are also good ideas. When driving is necessary, avoid energy-wasting behaviors: Keep the car serviced and the tires inflated, drive within the speed limit, accelerate gradually, and avoid drive-through lines.

Energy-Saving Technologies

Choose technologies that are appropriate for the specific task: For example, a small, fuel-efficient car can transport a family to a soccer game as well as a large sport utility vehicle. A clothesline can be used to dry clothes on a sunny day as well as clothes drier.

Around the house, use energy-efficient appliances and lighting that are operating well. Look for the EPA’s Energy Star when choosing energy-efficient products. When possible, switch to more efficient forms of lighting, heating, and cooling. In the long term, encourage and support energy-efficient building design, including renewable energy technologies such as solar panels. Because manufacturing uses a great deal of energy, try purchasing recycled products, which use less energy than products made from new materials.

Vehicle choice is extremely important. Small, energy-efficient vehicles are preferable to larger “gas guzzlers.” As gasoline prices rise, alternative vehicles become more popular. Hybrid cars are now widely available, and cars powered by liquid natural gas or fuel cells will be more common in the future.

Some activities waste enormous amounts of energy. For example, burning airplane fuel produces greenhouse gases, while airplane exhaust produces ice crystals that trap them. The total warming effect of air travel is 2.7 times that of the CO2 emissions alone. Driving or taking a bus or train presents a good alternative.

Be Politically Active

Work with government at all levels to encourage or require energy-efficient behaviors and technologies. Governments can do many things, including:

Tax energy to encourage conservation and energy efficiency, and to provide funds for research and development of new energy-efficient technologies.

Develop public transportation and increase the safety of biking by building bike lanes and installing bike racks in public places.

Provide tax incentives for households and businesses to adopt more energy-efficient strategies or to convert to carbon-free power sources.

Provide tax incentives for people buying low greenhouse gas-emitting vehicles, while eliminating tax incentives for people buying high-emission vehicles.

Influence energy-efficient development by designing communities that encourage walking and public transportation use.

Individuals can encourage local politicians to take action on reducing greenhouse gas emissions by promoting energy efficiency, mass transportation, and by developing alternative energy sources. Individuals can vote for national leaders who recognize the potential consequences of climate change and will take action. Political leaders can also be encouraged to see that the United States participates in international treaties that seek to limit greenhouse gas emissions.

Offset Carbon Emissions

People can now pay to offset the carbon they produce. An average car produces about 10,000 pounds (4,535 kg) of CO2 per year. To offset that amount, a driver can donate $25 to $50 to a carbon-­neutral organization. The money helps pay for the development of clean power by subsidizing the construction of new wind turbines or solar energy collectors, for example. Planting trees or buying forestland to preserve it is another way to offset carbon emissions. Organizations can counteract their carbon emissions, too: The Rolling Stones offset carbon emissions from a 2003 concert by donating money for planting trees in Scotland, and Ben & Jerry’s ice cream offsets the carbon it produces in manufacturing and retailing. For this strategy to actually offset carbon emissions, the money must fund a project that would not otherwise have been realized.

Buying carbon offsets to counteract greenhouse gas–producing behavior is controversial. Some environmentalists say that buying carbon offsets in conjunction with a conscious effort to reduce an individual’s emissions is a way to increase awareness of the global warming problem while supporting projects that may someday help with the solution. But others say that this market approach does nothing to reduce overall greenhouse gas emissions. While it allows people to feel good about contributing money to offset their carbon footprints, most are still engaging in environmentally destructive behaviors. No matter which side of this issue a person takes, there is no doubt that this is a growing business. Estimates are that people are buying more than $100 million per year in offsets, and that the amount is escalating rapidly.

Adaptation

Even if a radical reduction in greenhouse gas emissions could be rapidly achieved, temperatures would continue to rise due to greenhouse gases that have already been emitted and the thermal inertia in the climate system. How much temperatures rise depends on what mitigation strategies are developed and when they are begun. In the meantime, people, communities, and nations can respond to environmental changes after they happen, or they can anticipate and prepare for the changes.

Communities and nations differ greatly in the resources they have to protect their people from the impacts of climate change. Poor communities already rarely have enough resources to deal with immediate problems, such as poverty. Poor people lack the access to financial and natural resources and social services and, as a result, are often unable to rebuild their lives after a disaster. For adaptation to climate change to work, wealthier communities will have to assist poorer communities in developing their economies while reducing their greenhouse gas emissions and learning to use alternative technologies.

Adaptation before the predicted changes occur has a large cost benefit. Preparing for a disaster is less expensive and less disruptive to people’s lives than mopping up after one.

Hurricane Katrina

Is a tragic example of how planning could have decreased economic costs, the number of lives lost, and the number of those whose lives were disrupted. For decades, climatologists and coastal scientists had warned that a very powerful hurricane could break the levees that protected New Orleans from surrounding water. The levees were designed only to withstand a Category 3 storm. (In the meantime, for a variety of reasons,

the city had sunk to 20 feet [6 m] below sea level in some areas.) Despite these warnings, the recommended improvements to the levees were never made. Hurricane Katrina reached Category 5 as it traveled through the Gulf of Mexico but had dwindled to a Category 3 at landfall and was only a Category 1 or 2 as it passed over New Orleans. Although initially people thought that the city had been spared, the storm’s slow passage over the region was enough to break the levees. The resulting flood left 1,800 people dead while displacing about one million others from their homes. The economic impact is estimated at as much as $150 billion. By upgrading the levees so that they could have protected against a Category 5 hurricane, New Orleans would have been ready for this inevitable storm and the storm surge that accompanied it. This preparation would have been expensive, but compared to the cost of the damage caused when the levees broke, the cost would have been minor.

Other regions can adapt to climate change by recognizing and preparing for their own potential problems. Healthy ecosystems can protect coastal regions, and the original wetlands that once thrived on the Louisiana coast might have spared New Orleans some of the brunt of the hurricane. Hard structures, such as seawalls, are better used sparingly; but soft protection, such as beach nourishment, is wise, although it is very expensive. Increasing the capacity of rainwater storage systems may reduce the number of times a city floods and can be used to save water for drier times. It is necessary for evacuation plans for residents of storm-prone areas to be well thought out, easy to implement, and understandable by all who need them.

Although this is unlikely to happen until the effects of global warming are even more pronounced, coastal scientists recommend that communities retreat from the shoreline, and that new building takes place farther inland. Insurance companies can help to reduce coastal development by increasing rates for those who live in dangerous areas, as they are beginning to do in the hurricane-vulnerable regions of Florida. Federal insurance, which has allowed coastal development to thrive, can also be eliminated (with some compensation for those who own vulnerable property).

London is the first major world city to recognize the need for a detailed climate change adaptation plan. This old but vital city is mostly built on the floodplain of the River Thames, which is a tidal river. Adaptation to higher water levels began in the early 1970s when a movable barrier was built along the Thames to stop flooding from storm surges. In the early years, the barrier was closed no more than two times per year. In most of the years since 1986, the barriers have been closed between 3 and 19 times. The barrier was designed to mitigate sea level rise until 2030. The city is working on plans for what will come next for flood protection and also on plans for other impacts of climate change, including positive ones. For example, planners anticipate an increase in tourism and recreational activities as weather becomes more favorable in the United Kingdom and less attractive in the Mediterranean region. Some small communities are facing inevitable climate change with similar foresight. To adapt agricultural systems to a warmer world, agriculturalists may need to develop crop strains that require less water and less soil moisture. Farms may need to be moved to more climatically hospitable areas. Changing the timing of farming events, such as planting crops earlier, will need to continue. In southern Africa, where droughts have become longer, farmers are making changes such as seeking out crops that are better adapted to the current climate, planting trees to protect the soil, and diversifying their livelihoods.

Adaptation will be an effective response to warming only to a certain extent. If no changes in emissions are made, at some point the environmental changes will likely become too overwhelming, and the costs too great. One example is what could happen to South Florida, where a small increase in sea level would flood some of the lowest lying areas and make the coast more vulnerable to damage from hurricanes and other storms. While people may be able to prepare for these changes or at least mop up after large climatic events, this is very draining when it occurs on the scale of a major city, as has been seen in New Orleans. As sea level rises even higher, the entire southern portion of the state of Florida could flood. If this scenario comes true, at some point Floridians will need to give up trying to patch up the damage and relocate. The economic and social costs of doing this for an entire region are unfathomable.

Society is a long way from mitigating the problem of climate change. Doing so will require the political will to make the necessary changes to reduce emissions at all levels of human organization, from governments down to individuals. Drastically improving energy efficiency is the easiest change to make and can be rapidly initiated. Technological advances in energy use and even in carbon sequestration should be pursued. Over time, more brazen strategies, such as placing solar panels in space, may be possible. The longer action is delayed, the more drastic future changes will need to be. It is predicted that if society delays action for 20 more years, emissions reductions will need to be 3 to 7 times more than if the reductions begin immediately.

Which major cities are leaders in reducing greenhouse gas emissions

How to Reduce Your Greenhouse Gas Emissions

Step Two: Transform Energy Technology

Experts suggest that to substantially reduce greenhouse gas emissions, society must make a massive change in the way energy is produced and used. By the middle of the century, humanity must make a transformation to energy sources that produce zero-carbon emissions.

That is, society must move away from an economy based on the use of carbon-based fuels, called the carbon economy, to an economy based on sustainable energy sources, which are those that can be used without compromising the needs of future generations.

Developing Technologies to Reduce Greenhouse Gas Emissions

Zero­carbon and lower carbon energy sources that are already in use-solar, hydro, wind, geothermal, nuclear, and biofuels-could be improved and in some cases expanded. Solar energy taps the Sun directly rather than indirectly, as with fossil fuels. With the proper technology, solar energy can efficiently heat water or a building. Photovoltaic cells, also known as solar cells, convert sunlight directly into electricity. Solar cells arranged in solar panels on rooftops can provide energy to a building. Producing large amounts of electricity requires building huge arrays of solar cells into panels, parabolic troughs, thermal dishes, or power towers. Solar energy is renewable and produces no pollutants or greenhouse gases. The potential for solar power is enormous, particularly in sunny locations such as the southwestern United States.

Hydropower plants harness the energy of water falling over a dam, which spins the blades of a turbine to produce electricity. Hydroelectric energy is renewable and pollutant and greenhouse gas free. While hydropower produces about 24% of the world’s electricity, it cannot be further cultivated in developed countries because their rivers are almost all dammed. In developing nations, there are still free-flowing rivers that can be dammed, although people sometimes object to hydropower development because the water that backs up behind dams may flood regions that are of scenic or social value.

Wind energy is renewable, is nonpolluting, produces no greenhouse gases, and is widely available. To create usable power, wind turns turbine blades that are connected to a generator that transfers the energy into usable electrical current. Small wind turbines can be placed individually in open areas, but the large-scale use of wind energy requires a wind farm. Wind farms can be located anywhere conditions are good.

Offshore wind farms supply about seven times as much energy in the same amount of area as land-based farms, although the machinery is more prone to corrosion.

Wind energy has enormous potential. Estimates are that wind could supply 40 times the current demand for electricity and about 5 times the global consumption of power. Although wind currently only generates about 1,5% of global power usage, that amount represents more than a fourfold increase between 2000 and 2014. Technological improvements have brought down the cost of building wind plants by 80%, making wind arrays less expensive to build than any other type of power plant. Wind energy is still more expensive to generate than fossil fuel or nuclear power, but when the entire cost to health and the environment is factored in, wind is extremely competitive. New wind farms are being planned all over the world and are increasingly popular in the United Kingdom.

Geothermal energy harnesses the power contained in hot rock below Earth’s surface. Hot water may flow directly from hot springs, or water can be pumped into a region of hot rock and heated. The steam created by the contact of water with hot rock is then used to generate electricity. Geothermal energy is renewable, nonpolluting, and does not emit greenhouse gases. At the world’s largest dry steam geothermal field, located at the Geysers in northern California, sewage effluent from nearby cities is injected into the hot rock found there to create steam.

Research is ongoing on a more advanced geothermal technique, Enhanced Geothermal Systems (EGS), in which boreholes are drilled into rock to a depth of about 6 miles (10 km), a depth routinely drilled by the oil industry. The Massachusetts Institute of Technology reported in 2006 that with improved technology, EGS would be able to supply the world’s total energy needs for several thousand years. The steam from the deep holes could be cycled into an existing coal, oil, or nuclear power plant.

Nuclear energy was nearly dead after the 1979 partial core melt-down at the Three Mile Island plant in Pennsylvania and the 1986 explosion and meltdown at Chernobyl, Ukraine. Several European countries abandoned the use of nuclear power entirely, and the United States and countries in other parts of Europe halted the construction of new nuclear power plants. But concerns about global warming have brought about a resurgence of interest in nuclear power, which is clean and produces no greenhouse gases.

Nuclear power still has many opponents who question several aspects of its safety: Nuclear power plants have a history of accidents, transporting nuclear materials exposes many people to potentially harmful radiation, and the waste generated is hard to dispose of because it remains radioactive for more than 10,000 years. Proponents of nuclear power say that the technology is well developed, and plants could come online quickly, allowing the world to lessen its reliance on fossil fuels rapidly. Plus, they say, the problems associated with nuclear power plants are being solved: New designs reduce the possibility of catastrophic accidents, and development is under way for the safe disposal of long-lived radioactive wastes for more than the required 10,000 years at Yucca Mountain, Nevada, in the United States. Still, this debate is likely to continue for a long time. There are two types of nuclear power. Nuclear fission power plants use enriched uranium as their energy source. Nuclear power is clean, but the uranium it needs must be mined and is nonrenewable. Current estimates are that if fossil fuels were replaced by nuclear fission, there would be only enough uranium to last anywhere from 6 to 30 years. Uranium can theoretically be collected from seawater, but that technology is a long way off. In a breeder reactor, the byproducts of nuclear fission are made to breed new fuel. No country yet has a functioning breeder reactor, although this research is ongoing.

Nuclear fusion takes place when the nuclei of light elements combine to form heavier elements, just as the Sun fuses hydrogen into helium. Energy produced from nuclear fusion is enormously desirable: clean and very efficient. Fusion reactions produce far more energy per unit of fuel than nuclear fission or any other energy source. For example, 0.04 ounces (1 gram) of nuclear fuel holds the same amount of energy as 2,483 gallons (9,400 liters) of gasoline. Once started, fusion reactions are self-sustaining.

Some of the qualities that make fusion energy attractive also make it problematic. The fusion of two isotopes of hydrogen, deuterium and tritium, takes place at enormously high temperatures of about 180 million °F (100 million °C). In a hydrogen bomb, fusion is initiated by the detonation of a fission bomb, and the reactions proceed until the material runs out. Because a reactor cannot be the site of a nuclear bomb detonation and cannot contain such enormous temperatures, scientists are researching the possibility of a process called cold fusion, which occurs at normal temperatures and pressures. Although progress is being made, there is no guarantee that fusion will be able to replace carbon-producing energy in any significant way by the middle of this century.

Biofuels harness the Sun’s energy that is stored in plant and animal tissue. Biomass can be used directly, as when wood, charcoal, or manure is burned to cook food or heat homes. Fuel can also be created by changing the form of biomass. Ethanol, for example, is liquid biofuel produced from plant material and can be burned in cars and other vehicles in place of gasoline. Typical ethanol is produced from plant sugar, such as the sugar in corn. Cellulosic ethanol is made from plant fiber, or cellulose, such as corn stalks. Cellulosic ethanol from crop waste could supply about 25% of the energy needed for transportation in the United States while creating about 85% less greenhouse gases than typical gasoline. Biodiesel is another liquid fuel and can be made from fats such as used cooking oil, animal guts, used tires, sewage, and plastic bottles.

Although biofuels burn cleaner than fossil fuels, they are not pollutant free. Ethanol from corn creates about one-third less greenhouse gases than regular gasoline. Because the CO2 was taken from the environment recently, its addition back into the atmosphere has no net effect (unlike fossil fuels, which emit CO2 that was sequestered). Because they burn more cleanly than fossil fuels, biofuels are used as a gasoline additive in the United States. One fuel, called E85, is 85% ethanol and 15% gasoline. Ethanol fuel is as much as 25% less efficient than gasoline per gallon. Biofuels have limits as an alternative fuel source. Cellulosic ethanol is limited by the amount of suitable agricultural waste, which is far less than the amount of fossil fuels used each year. Growing crops to be made into biofuels is extremely inefficient. For example, because fossil fuels are used extensively in pesticides, in fertilizers, and for performing mechanical labor, there is little or no energy gained from biofuels through using crops such as soybeans or rapeseed. Ethanol derived from corn on a large scale is already credited with increasing food prices because corn is a basic crop in much of the food industry, where it is used in a large variety of products, from animal feed to corn syrup. A 2005 paper by David A. Pimentel of Cornell University and Tad W. Patzek of the University of California, Berkeley, stated that the cornto­ethanol process powered by fossil fuels consumes 29% more energy than it produces. The results for switch grass were even worse, the paper said, with a 50% net energy deficit. Dr. Pimentel said in a 2006 interview in The New York Times, “Even if we committed 100% of the corn crop to making ethanol, it would only replace 7% of U.S.

vehicle fossil fuel use.” Other scientists say that biofuels provide a reasonable alternative to fossil fuels if the right crops are used and ethanol plants become more efficient. Algae contain much more usable oil than land-based crops  and could be fed agricultural and other wastes, although at this time research into algae biofuel is in the early stages.

Fuel cells may someday be used in motor vehicles, but will not be ready for mass production for some time. Fuel cells are extremely efficient at harnessing the energy released when hydrogen and oxygen are converted into water. Fuel cells form the basis of what is known as the hydrogen economy.

A fuel cell is made of an anode compartment (negative cell) and a cathode compartment (positive cell), which are separated by a porous disc known as the proton exchange membrane. A catalyst, which aids in chemical reactions, is located on the membrane. The membrane conducts positively charged ions and blocks electrons. In a hydrogen and oxygen fuel cell, pressurized hydrogen gas is sent into the anode compartment, and oxygen gas is sent into the cathode compartment. At the anode, hydrogen gas is forced through the catalyst and is split into electrons and protons. The protons move to the cathode side, and the electrons are conducted through the external circuit to produce electricity. At the cathode, the oxygen gas is sent through the catalyst and splits into two oxygen atoms. These ions have a strong negative charge and attract the two positively charged hydrogen ions and two of the electrons from the external circuit. The catalyst is dipped into each compartment, which assists in the reaction of oxygen and hydrogen.

The products of this reaction are water vapor and heat. To convert a significant amount of energy, fuel cells must be stacked together. Unfortunately, there are many problems with fuel cell technology. Hydrogen does not exist in vast reservoirs, but must be created. It is also difficult to store and use. One solution is to use a reformer, which turns hydrocarbon or alcohol fuels, such as natural gas, propane, or methanol, into hydrogen. Most of the  current generation of fuel cells runs on the hydrogen in natural gas. But collecting the compound uses up a great deal of energy and, at this time, produces more CO2 than burning the fossil fuel directly. Obtaining hydrogen from natural gas decreases fuel cell efficiency and increases the production of waste heat and gases.

Fuel cell technology is promising in other ways. Besides the incredible efficiency when pure hydrogen is used, the oxygen needed for hydrogen-oxygen fuel cells is widely available in the air. However, while vehicles that run with hydrogen fuel cells create no emissions, they do produce CO2. Unless this gas is sequestered, using hydrogen fuel cells to run vehicles will not solve the global warming problem. Fuel cells that use compounds other than hydrogen are now in development. While the use of fuel cells is still in its infancy, it is now entering a rapid growth phase, with revenue projected to grow to $15.1 billion in 2014. According to the Society of Automotive Engineers in 2007, “Fuel cell energy is now expected to replace traditional power sources in coming years-from micro fuel cells to be used in cell phones to high-powered fuel cells for stock car racing.” Fuel cells are already replacing batteries in portable electronic devices because they last longer and are rechargeable. Even so, many drawbacks remain in developing fuel cells as energy sources, as discussed above. Converting hydrogen to another form of energy requires electricity, which must be generated from conventional energy sources with their typical costs. In a 2005 Science article, a team of Stanford researchers suggests that these costs would be minimized, and pollutants would be negligible, if the hydrogen was pumped into the fuel cells using wind power. The authors state, “Switching from a fossil-fuel economy to a hydrogen economy would be subject to technological hurdles, the difficulty of creating a new energy infrastructure, and considerable conversion costs but could provide health, environmental, climate, and economic benefits and reduce the reliance on diminishing oil supplies.”

Power from coal is so integral to modern society that many energy experts believe that technologies must be developed to make coal burning more environmentally sound. As a result, clean coal, which is more efficient and produces far fewer emissions than normal coal, is becoming an important, but controversial, topic. To produce clean coal, emissions from coal-fired power plants are reduced by gasification. In gasification, the coal is heated to about 2,500°F (1400°C) under pressure to produce syngas, an energy-rich flammable gas. After cleansing, syngas is combusted in a turbine that drives a generator, and then the waste heat powers a second, steam-powered generator.

Syngas burns cleanly and is easily filtered for pollutants. Overall emissions of most air pollutants from syngas are about 80% less than emissions from traditional coal plants. Greenhouse gas emissions, particularly CO2, are also lower. Gasification has other positive features: It makes dirty coal usable, which benefits regions where only dirty coal is available. Also, because the gas is cleansed before it is burned, gasification plants don’t need expensive scrubbers-the devices that eliminate particulates, SO2, hydrogen sulfide, and other pollutants from the waste gases. Clean coal can also be liquefied and burned like gasoline.

Gasification has many downsides. A gasification plant costs 15% to 50% more to build and 20% to 30% more to run than a normal coal-fired plant. Due to these additional costs, conversions to clean coal plants will probably not become widespread until industry is given financial incentives or emissions caps. To produce syngas, gasification uses a great deal of energy, about 10% to 40% more than a standard coal-fired power plant. Also, coal mining is very often environmentally damaging. As yet, although gasification has been tested, it has not been used in a full-scale power plant.

Removing Carbon After It Is Emitted

An alternative to reducing greenhouse gas emissions is sequestering the emissions after they have been created. Carbon can be sequestered in natural systems, or technologies can be developed for carbon sequestration.

Natural carbon sequestration can be enhanced, for example, by reforesting on a large scale. Unfortunately, the opposite is happening as enormous expanses of forest are being cleared for slash-and-­burn agriculture. Forest preservation and reforestation are economically and politically complex issues.

Another approach to sequestration that has been researched is iron fertilization. In those parts of the ocean where the presence of nutrient iron is limited, scientists have discovered that adding iron dust to the ocean stimulates a plankton bloom. The plankton remove CO2 from the atmosphere, although for this to work as a means of sequestering carbon, the plankton must then sink out of the system into the deep sea or into seafloor sediments. While small-scale experiments have confirmed that iron fertilization stimulates plankton growth, no one is certain how large-scale fertilization would affect plankton, or how large-scale blooms would affect the oceans. Recent work has shown that there are few locations in the oceans where the plankton would be removed from the system, and climate scientists currently think that iron fertilization will not make much difference to global warming. Finally, another way to sequester carbon is by increasing the content of organic matter in soils in order to increase the amount of carbon in that soil. Farming techniques that protect soil, such as no till farming and crop rotation, can help sequester carbon.

Artificial carbon sequestration is another possible approach. CO2 from power plants and other large sources can be captured and stored. Carbon is easily captured in gasification plants, where CO2 emissions can be reduced by 80% to 90%, and from natural gas and biofuel plants. Once the CO2 is captured, it is transported by pipelines or by ship to a storage site. CO2 can be stored in rock formations, the oceans, or carbonate minerals. The most promising idea is to inject CO2 into salt layers or coal seams where the gas cannot escape to the surface. (When CO2 is added to nearly spent oil and gas fields, it actually flushes out some of the uncollected oil.) Reports by the Intergovernmental Panel on Climate Change (IPCC) suggest that sites could be developed that would trap CO2 for millions of years, with less than a 1% leakage rate for every 1,000 years.

Several sequestration projects are currently under way. Norway is injecting CO2 from natural gas into a salt formation in the North Sea. CO2 from a coal gasification plant in North Dakota is being used to enhance oil recovery in a reservoir in Canada. British Petroleum is involved in a project in Algeria that will store 17 million tons of CO2.

The Wrong Direction

Besides concerns about greenhouse gas emissions, fossil fuel supplies are dwindling.

Sometime before 2010, society will pass peak oil. Peak oil occurs when half of the oil that was ever available for extraction has already been pumped. Although it might seem that a lot of oil would still be left, what remains is generally lower grade, located in remote locations, and harder to extract. Besides that, if the carbon economy continues unaltered, by 2030 the demand for fossil fuels could be nearly 50% higher than it is today,

largely due to increased use by developing countries: China’s demand is expected to double over 15 years, and India’s may double in 30 years. For all of these reasons, the energy industry is looking for other sources of energy, particularly fossil fuels. Two of these possible sources are oil shale and tar sands.

A rock that contains oil that has not migrated into a reservoir is called an oil shale. Oil shale is mined in open pits. After mining, the rock is crushed, heated to between 840°F and 930°F (450°C and 500°C), and then washed with enormous amounts of water. This entire process creates petroleum, which can then be extracted from the rock. The amount of fuel available as oil shale is comparable to the amount remaining in conventional oil reserves. The United States holds 60% to 70% of the world’s oil shale, mostly in the arid

regions of Wyoming, Utah, and Colorado. These oil shale resources underlie a total area of 16,000 square miles (40,000 km), a little less than the combined area of Massachusetts and New Hampshire. Tar sands are rocky materials mixed with oil that is too thick to pump. Tar sands are strip mined, so many tons of overlying rocks are dumped as waste. Separating the oil from the rocky material requires processing with hot water and caustic soda. Tar sands represent as much as 66% of the world’s total reserves of oil; about 75% of this reserve is in the Canadian province of Alberta and in Venezuela. Extraction of both these sources of oil comes with environmental costs. Both require large amounts of water for processing- by chance, many of these deposits are found in arid areas. Plus, since the oil and tar are spread out, the rock must be mined over a large area. Not only does this degrade the landscape and create a large amount of waste rock, environmental restoration after mining is difficult. As for climate change, extracting usable energy from tar sands produces four times as much greenhouse gas as processing the same amount of conventional oil. This is true to a lesser extent of oil shale as well.