Carbon Offsets

Carbon offsets are emissions-saving projects intended to compensate for ongoing and increased pollution in industrialized, developed countries. The majority of these projects are undertaken by companies, international financial institutions, and governments. Offsets are usually part of capand- trade schemes, in which the cap is supposed to set a limit on pollution. Offset projects generate credits that allow pollution over and above this limit.

The United Nation’s (UN) Clean Development Mechanism (CDM) is the largest offsetting scheme, with almost 3,000 registered projects for third-world and developing countries as of April 2011 and over 3,100 further projects awaiting approval. Based on 2011 prices, the credits generated by approved schemes were scheduled to be worth over 11.5 billion euros by 2012.

In 2008, Stanford law professor Michael Wara and Laboratory on International Law and Regulation Director David Victor reviewed the world’s largest carbon offset market—the Kyoto Protocol Clean Development Mechanism. They discovered the following: (1) much of the current CDM market does not reflect actual reductions in emissions, (2) offsets were not likely to be effective costcontrol mechanisms, (3) the demand for credits in emissions-trading systems were likely to be out of phase with the CDM supply, and (4) the rate at which CDM credits were being issued in 2008—at a time of high demand—was only one-twentieth to one-fortieth the rate needed for the current CDM system to keep pace with the projects it had already registered.

In addition to the problems in carbon markets observed and documented by Wara and Victor, in 2009, Hannah Wittman of Simon Fraser University and Cynthia Caron of the Polson Institute for Global Development at Cornell University documented on-the-ground problems with some of the first carbon offset projects in the world, in Guatemala.

In 1988, Applied Energy Services (AES) was constructing a 183 MW, coal-fired power plant in Connecticut. AES hired World Resources Institute to find a forestry project to offset the 14.1 million tons of carbon that would be emitted over the power plant’s 40-year life. The following year, AES signed an agreement with the nongovernmental organization CARE International to fund an ongoing agroforestry project in Guatemala.

The report noted that in the first decade, the project failed to offset the emissions from the AES coal-fired power plant. In addition, turning the project into a carbon project diverted project resources from poverty alleviation to carbon measuring. The reasons cited in the report for this failure included “land use conflicts, struggles for control over scarce forest, and legal changes that criminalized subsistence activities such as fuel wood gathering [and] undermined local farmer participation.” Guatemala’s 1996 forest law declared forestland off-limits to farmers. The law effectively took access to forests away from local people.

At the same time, the main goal of the project deliverer, CARE International, is neither forestry nor carbon accounting. As a development organization, CARE prioritizes rural farmers’ needs for poverty alleviation before carbon mitigation. To maintain project funding, however, it needed to achieve mandated targets in establishing carbon sinks. The tension CARE staff experienced in attending to both carbon sequestration and poverty alleviation mirror the difficulties that extension agents face in reaching their targeted population:

when the objective of rural poverty reduction does not overlap with that of increasing carbon sinks, where do they direct their scarce resources?

Carbon Markets

Global environmental markets became a topic only after the approval of the Kyoto Protocol in 1997, which provided a foundation for the development of the first global carbon market. Carbon markets have been promoted by industry advocates such as the International Emissions Trading Association (IETA), some conservation nongovernmental organizations (NGOs), and some governments as a way to generate enough money to enable industries and countries to reduce their carbon dioxide (CO2) emissions. However, concerns about the efficacy and fairness of carbon markets have been raised, and Interpol, the world’s leading policing agency, has warned that organized crime easily takes advantage of carbonmarket schemes.

History

In the early 1990s, when the Kyoto Protocol was being debated at the United Nations Framework Convention on Climate Change (UNFCCC) negotiations, no country wanted markets as part of a climate agreement except the United States, says Payal Parekh, a Swiss-based climate scientist and energy expert. The Kyoto Protocol, which was adopted in 1997 and entered into force in 2005, sets binding targets for 37 industrialized countries and the European community for reducing greenhouse gas (GHG) emissions, which amount to an average of 5 percent against 1990 levels over the five-year period between 2008 and 2012. The United States subsequently refused to ratify the protocol, but the market component remained.

That legacy has resulted in carbon-offset markets that allow developed countries to continue to emit carbon while they invest in “emissionssaving projects” in less-developed countries. The biggest of these offset markets is the UN’s Clean Development Mechanism (CDM), with almost 3,200 registered projects so far in Africa, the Asia–Pacific region, eastern Europe, and Latin America and the Caribbean. In order to truly reduce emissions, the money invested by developed countries must be applied to emissionreduction projects that would not have otherwise been possible. However, the CDM has been widely criticized, as several studies estimate that 20 to 90 percent of CDM projects do not result in lower emissions overall.

European Emissions Trading System

The world’s biggest carbon market is the EU Emissions Trading System (EU ETS), which accounted for 95 percent of the $144 billion in carbon transactions in 2010. The aim has been to “cap” GHG emissions, but several available sources show that the EU ETS has failed to reduce carbon dioxide emissions. According to Steve Suppan, senior policy analyst at the U.S.-based Institute for Agriculture and Trade Policy (IATP), “Carbon markets are open to fraud, misrepresentation, and deceptive promotion.”

In studying the EU ETS, organizations such as Carbon Trade Watch discovered there were extra costs associated with setting up carbon markets that had not been disclosed or anticipated. Hazel Henderson, author and president of Ethical Markets Media in the United States and Brazil, observed:

There was a failure to disclose that setting up carbon caps and trading mechanisms actually entailed the creation of costly, complicated new bureaucracies. Monitoring, verifying the offsets, RECs (renewable energy certificates) while lowering the levels (caps) on CO2 emissions was opposed by the polluters. The CO2 permits were to be auctioned, but this quickly turned into massive giveaways to polluters, which then sold them at a profit, as global levels continued to rise. Thus, “cap and trade” turned out to be less efficient then direct taxing and regulation.

At the same time, the rethinking of climate policy produced two groundbreaking reports from the Intergovernmental Panel on Climate Change (IPCC) and UNFCCC with the World Meteorological Organization. They advised broader approaches to global emissions beyond CO2 to focus on soot, methane, volatile organic compounds (VOCs), and ozone—pointing out that this approach could decelerate global warming more rapidly.

Additionally, the EU ETS has experienced high levels of fraud. Earlier in 2011, according to reports by InterPress, carbon credits worth $38 million disappeared in the EU’s carbon market after computer hackers transferred funds from the Czech Republic to Poland, Estonia, and Liechtenstein—the fourth time funds had been stolen or mislaid. Suppan notes: “a lawyer formerly involved in carbon trading told me that if markets are still trading carbon 10 or 15 years from now, then the global environment will be in very big trouble.”

Several carbon-trading firms laid off significant staff in 2011, because of lackluster volumes in the European Union Allowance (EUA) and UN offset markets and weakening prices amid uncertainty about EU’s 2020 climate target and a future global climate regime. Moreover, institutional investors, such as pension funds, were much less interested in carbon markets than they were in 2010.

A recent collapse in EU prices is a signal that the trading scheme could be oversupplied through the entire third phase (2013–20). This has convinced many funds that the carbon market isn’t worth the outlay.

Carbon Footprint

A carbon footprint is defined as the total amount of carbon dioxide (CO2) and other greenhouse gases (GHGs) such as methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) that are emitted directly and indirectly from human activities such as the burning of fossil fuels, deforestation, livestock raising, and agricultural production. Calculating a carbon footprint is a tool for understanding the amount of global warming gases created by everyday activities. For example, when a living space is heated with oil, gas, coal, or electricity, a certain amount of CO2 is emitted. In addition, when consumer items are sold in a store, the production, transportation, and packaging of these products also create a certain amount of CO2 and other GHGs. A carbon footprint is the sum of the total amount of CO2 produced by human activities in a given time frame (typically one year). Carbon footprints are generally expressed in annual tons of CO2.

The carbon footprint is not only a method of estimating the amount of CO2 and GHGs humans are producing, it is also a way to understand the chemical nature these substances have in different parts of the atmosphere. The creation of CO2 and other GHG molecules from the burning of fossil fuels have different chemical behaviors than their original fossil fuel molecules. Many GHG molecules produced from human activities accumulate in parts of the atmosphere where they have an undesirable effect. For example, the production of ozone gas (O3) is desirable in the stratosphere (upper atmosphere), where it protects humans from harmful UV radiation; however, an abundance of O3 in the troposphere (closer to where humans live) is undesirable because it acts as a lung irritant for people with respiratory illnesses (such as emphysema, asthma, and chronic bronchial inflammatory diseases) and contributes to smog production.

Determining the Source and Impact

The largest sources of CO2 from the burning of fossil fuels are: liquid fuels (such as gasoline or diesel), 36 percent; solid fuels (such as coal and wood), 35 percent; gaseous fuels (such as natural gas), 20 percent; international bunkers (fuel used for international aviation and maritime transportation), 4 percent; and cement production, 3 percent. The most common human activity that produces an abundance of CO2 in the atmosphere is burning liquid fuels in automobiles.

Other GHGs produced from the burning of liquid fuel in engines include, but are not limited to, methane and ozone gas (CH4 and O3, respectively). One method for estimating the amount of CO2 and other GHGs produced by human activities is determined from a balanced chemical equation (for example, stoichiometry) and then converted to an equivalent amount of CO2, which allows it to be combined in order to determine the individual, household, city, state, nation, or total global carbon footprint. Human activities on the entire planet produce approximately 27,500 million tons of CO2 annually. In 2006, China surpassed the United States as the number one emitter of CO2, with 6,200 million tons annually. The U.S. emissions of CO2 was 5,800 million tons, according to the Netherlands Environmental Assessment Agency. However, on a per-capita basis, the average Chinese citizen is responsible for 10,500 lb. (4,763 kg) of CO2, while the average U.S. citizen is responsible for 42,500 lb. (19,278 kg) as a result of driving, traveling by airplane, heating and electricity for a living space, and purchasing manufactured products.

There are a significant number of online carbonfootprint calculator tools available, ranging from the very basic to the very complex, which demonstrates an increased public awareness and interest in understanding how individuals, groups, and/or countries utilize carbon-based resources. Most of these tools provide a basic snapshot of an individual’s carbon footprint. A typical basic carbon footprint example is Yahoo Green: Your Carbon Footprint. A more comprehensive example of an individual/household footprint can be found with the Carbon Footprint Calculator, which covers consumption of energy, flights, transportation, lifestyle, and food preference. Businesses can use the TerraPass Carbon Balanced Business program. For a country-by-country comparison, the researchers at the Norwegian University of Science and Technology and the Centre of International Climate and Environment Research in Oslo have created a detailed country footprint that includes countries’ transportation and manufactured goods.

There are a number of groups and organizations working to create a more scientifically literate population as well as propose and implement programs and policies that reduce CO2 and other GHGs. The Clean Development Mechanism (CDM), a provision in the Kyoto Protocol, is an offset that allows more developed countries to invest in lower emissions-producing facilities in developing or less-developed countries to avoid reducing emissions in their home countries. Another proposal is a carbon tax, or the taxation of burning fossil fuels (such as liquid, solid, and gaseous fuels) to reduce CO2 emissions. Some groups are proposing a carbon label, where consumer products would report their carbon footprint on the label. Other practical methods for reducing carbon footprints are to; reduce driving (by using public transportation or bicycles), reduce household heating by a couple of degrees, purchase green energy, plant a tree, recycle, and buy products with reduced packaging.

Carbon Dioxide Equivalent

Carbon Dioxide Equivalent (CO2e) is a term used in climate science to explain the global warming potential of the various greenhouse gases (GHGs) by comparing each gas to the most prevalent GHG, carbon dioxide (CO2). The basis for this concept is found in the comparative radiative forcing of the various gases.

The use of CO2 as a common denominator simplifies the process of measuring changes in GHG emissions, as countries attempt to meet the mitigation targets agreed under various conventions. Global warming potential (GWP) is not a static concept, but rather measures the cumulative radiative impact of GHGs over various time periods using the CO2e metric. Conventionally, the GWP of a GHG is understood to be its radiative impact over a 100-year period.

Using this principle, the Intergovernmental Panel on Climate Change (IPCC) has determined that the GWP of the various gases are as follows:

• Carbon dioxide (CO2): 1

• Methane (CH4): 21

• Nitrous oxide (N2O): 310

• Hydrofluorocarbons (HFC): 1,300 to 11,700 (there are eight different forms of HFC)

• Chlorofluorocarbons (CFC): 6,500 to 9,200 (there are four different forms of CFC)

• Sodium hexafluoride (SF6): 23,900

The final determination of GWP is based on a number of factors, including the infrared-absorbing ability of each gas as well as its natural decay rate (the amount removed from the atmosphere over a given number of years). As this suggests, the actual and relative GWP of GHGs will vary depending on the time horizon used. The current scientific consensus is that a 100-year period is sufficiently long to enable valid and reliable comparisons. Radiative forcing is defined by the IPCC as follows:

… a measure of the influence a factor has in altering the balance of incoming and outgoing energy in the Earth-atmosphere system and is an index of the importance of the factor as a potential climate change mechanism … radiative forcing values are for changes relative to preindustrial conditions defined at 1750 and are expressed in watts per square meter (W/m2).

In short, radiative forcing is a measure of changes in the way the planet absorbs and re-radiates heat energy (infrared rays), typically because of anthropogenic (human-induced) causes. Such changes could also be because of causes other than human intervention, but in the context of climate change, the term is used only for changes in the radiation balance imposed by anthropogenic factors and excludes other variables such as changes in stratospheric dynamics, changes in trophospheric motions or in the troposphere’s thermodynamic state, or dynamically induced changes in the amount and distribution of atmospheric water.

As indicated in the IPCC’s definition, the assumed start date for measuring impacts is 1750, the notional beginning of the Industrial Revolution. The idea of using CO2e as a basis for comparing GWP was introduced by the IPCC in its First Assessment Report (1990), although at the time, the convention of using the 100-year time horizon had not been clearly established, and the specific figures varied somewhat from later conventions— for example, methane is given a value of 21 in the 1990 report, but nitrous oxide has a value of 290.

Under the Kyoto Protocol, the Conference of the Parties decided (decision 2/CP.3) that the values of GWP calculated for the IPCC Second Assessment Report (1995) were to be used for converting the various GHG emissions into CO2 equivalents when computing overall sources and sinks. The values used in the IPCC Third Assessment Report (2001) are slightly different; methane is given a GWP of 23. When Kyoto was signed in 1997, the 1995 Second Assessment Report was seen as the most credible source for these values, although some authorities permit more recent data to be introduced.

Carbon Cycle

The carbon cycle describes the biogeochemical cycle, or routes by which carbon atoms are exchanged through nested networks of environmental systems from the atmosphere into the biosphere, through photosynthesis and back again with respiration, decomposition, and biomass burning. Elemental carbon is a traditional component of the hydrosphere, atmosphere, geosphere (rocks, such as limestone; coal; and soils), as well as the biosphere (all living things).

The carbon cycle also involves the process of removal and uptake of carbon on a global scale. This process involves components in food chains; the atmosphere, as carbon dioxide; the hydrosphere; and the geosphere. The major movement of carbon results from photosynthesis and respiration. Carbon is present in the planet in the following major reservoirs: as the gas carbon dioxide (CO2) in the atmosphere; as organic matter in soils; as organic molecules in living and dead organisms found in the biosphere; in the lithosphere as fossil fuels and sedimentary rock deposits such as limestone, dolomite, and chalk; and in the oceans as dissolved atmospheric CO2 and calcium carbonate shells in marine organisms.

The carbon cycle has a large impact on Earth, both globally and locally. At the global scale, the carbon cycle influences Earth’s climate by regulating the amount of CO2, a principal greenhouse gas, in the atmosphere. Terrestrial ecosystems store as much carbon as the atmosphere, so plants and soils play an important role in regulating climate. The carbon cycle also plays a primary role in keeping ecological systems in balance, since it is involved in basic ecological processes such as plant growth and accumulation, and the death and decay of plant material.

As a principal building block of organic matter, carbon is utilized by biotic components of an ecosystem, especially by organisms for structural growth: a portion of elemental carbon that a living thing takes in is usually incorporated into its tissues. Thus, the carbon cycle is one of the most important biogeochemical cycles to humans, because it is a vehicle through which one of the primary elements required for the formation of human tissues is cycled, and also because it is a means through which elemental carbon is introduced to plants, the basis of human food.

The carbon cycle is also important to the human climate system because it sets the background for the environment, through CO2 and methane (CH4), which are major drivers of global climate temperatures. The carbon atoms present in the atmosphere, hydrosphere, biosphere, and the geosphere are able to move from one of these environmental systems to another as part of the carbon cycle.

The carbon cycle is sometimes conceptualized as four major carbon sinks, interrelated by nested systems of pathways for transport of carbon atoms. The carbon reservoirs are the air (atmosphere), considered as the starting point of the cycle; seawater and oceans (hydrosphere), which include biotic and abiotic marine biota; sediments (fossil fuels); and terrestrial biosphere, which includes freshwater systems (lenthic or lotic), as well as nonliving organic substances, such as soil carbon. The carbon cycle is primarily controlled by a series of biological, physical, chemical, and geological processes within the environment.

In the atmosphere, carbon exists primarily as the gas CO2. It is this form that plants transform into carbohydrates via photosynthesis, releasing oxygen in the process. This process is mainly carried out in autotrophs (terrestrial and aquatic plants such as algae and cyanobacteria). They produce their organic compounds using atmospheric CO2, with solar radiation providing the source of energy for the process. However, a minor group of autotrophs harness chemical energy sources for the production of their organic compounds through a process called chemosynthesis.

Through the food chain, carbon is transferred as autotrophs (producers) and eaten by heterotrophs or as heterotrophs feed on other organisms. When the plants and animals die, their carcasses, stems, or leaves decompose, releasing the carbon trapped in them into the geosphere. Some could be buried, and over time, will become fossil fuels. Food webs serve as part of a carbon atom’s journey through the carbon cycle. Carbon is returned to the biosphere during cellular respiration.

Biomass burning has the ability to transport substantial amounts of carbon into the atmosphere. When humans burn fossil fuels to run industries, power plants, cars, airplanes, and jets, a significant portion of carbon is transferred directly into the atmosphere as CO2. When autotrophs and heterotrophs die, their remains may settle as sediments in freshwater and marine ecosystems. The carbon trapped in sediments is eventually released into the aquatic environments through geological and chemical processes. Marine animals use the released carbon to build their skeletal materials.

Ultimately, the stored carbon compounds in these organisms up the web are broken down by decomposition, and the carbon is released as CO2 back into the cycle to be used by plants. The world’s oceans act as sinks for CO2, and, in general, contain more than 90 percent of the carbon involved in the global cycle. The concentration of atmospheric CO2, which is an important driver of climate change, influences the temperature of the Earth’s surface, which is largely determined by the ocean. The levels of CO2 in surface water, and hence in the atmosphere, are usually kept lower than that in deep water by two principal natural processes: the solubility pump and the biological pump.

Black Carbon

Black carbon (BC) is an aerosol pollutant emitted as a byproduct of the combustion of organic matter, and is a component of soot or ash. Sources of BC include cooking and heating stoves, industrial plants, coke and brick kilns, diesel combustion, agricultural burning, and oil and gas flaring. Researchers estimate that approximately 20 percent of global BC emissions come from the burning of biofuels, 40 percent from fossil fuels, and 40 percent from biomass burning. There are very high levels of uncertainty surrounding how much BC is emitted globally each year, and it is difficult to quantify current and past emissions of BC from biomass burning. As countries industrialize, they tend to become greater sources of BC from fossil fuels. The largest BC emitters are the major emerging economies, including China, India, and Brazil. From 1950 to 1990, the largest emitters were the United States, Europe, and other industrializing regions, particularly in Asia.

Unlike carbon dioxide (CO2), which stays in the atmosphere for centuries, the atmospheric lifetime of BC is on the scale of days to weeks. This short lifetime means that BC, like a number of other short-lived climate forcers such as methane and some hydrofluorocarbons (HFCs), has disproportionately large short-term climate impacts, and that large-scale reduction of BC emissions could significantly contribute to the reduction of near-term climate change.

BC particles also generally travel shorter distances than globally distributed greenhouse gases (GHGs) because of this short atmospheric lifetime, making BC primarily a localized source of pollution and a regional and local mitigation issue. As a major component of fine particulate matter (PM), BC is a large contributor to local air pollution and is detrimental to human health. Black carbon is a large component of soot from household cookstoves, contributing annually to the death of approximately 2 million people in the developing world.

Climate Impacts of Black Carbon

BC is believed to be a large net contributor to global warming, though there is a wide range of estimates for the magnitude of its radiative forcing (a measure of instantaneous warming of the atmosphere). Some scientists believe that BC’s contribution to global climate change is second in magnitude to CO2, accounting for approximately 18 percent of current radiative forcing; other scientists place BC third, behind methane. However, BC has complex and varying effects on warming throughout the atmospheric layers and at the surface.

Generally, the direction and magnitude of BC’s climate forcing in any given instance depends on where it is located in the atmosphere and the nature of other aerosols with which it is mixed. In order to devise optimal mitigation strategies, BC’s climate impacts are best considered in the context of the impacts of all pollutants with which BC is co-emitted.

By itself, BC absorbs solar radiation and contributes to warming by reducing the Earth’s albedo, both in the atmosphere and when deposited on the ground, particularly on snow and ice. However, other aerosols with which BC is consistently mixed (e.g., sulfates, nitrates, organic carbon, and other ash components) contribute to cooling by reflecting solar radiation and assisting in cloud formation. This mix of aerosols, including BC, can form atmospheric brown clouds (ABCs), which can be continental in size and up to 3 mi. (5 km) in height. ABCs have a negative radiative forcing, which may counteract as much as 50 percent of warming from other GHGs. Black carbon and other aerosols can also contribute to cooling near the surface by absorbing solar radiation, thereby causing dimming. However, new research is showing that BC and ABCs contribute significantly to warming in the lower atmosphere by exacerbating solar heating.

Studies have shown BC to have acute warming impacts in landscapes with significant snow and ice coverage, including the Himalayas and the Arctic. Through atmospheric warming, BC is believed to contribute to an increase of 1.08 degrees F (0.6 degree C) in the Himalayas, causing glacial retreat. Through its ability to decrease albedo of snow and ice, BC is posited to be the greatest contributor to melting of Arctic sea ice. Black carbon not only causes climatic impacts, but may also impact the hydrologic cycle, increasing atmospheric humidity and rainfall in certain areas. For example, studies show that BC emissions in south Asia are impacting seasonal monsoon rains. Black carbon emissions are shown to have wide-ranging health effects, particularly for respiratory and cardiovascular health. Thus, reductions in BC emissions are likely to carry significant social and environmental benefits.

Reducing Black Carbon Emissions

Black carbon is rapidly removed from the atmosphere by precipitation (wet removal) and wind or gravity (direct deposition), resulting in a very short atmospheric lifetime of approximately one week. Thus, reducing BC emissions is a shortterm strategy for addressing climate change and has the potential to head off up to several degrees of warming in certain regions.

Given the broad array of BC sources, there are many possible strategies and policies for reducing BC emissions. Air quality standards for PM10 and PM2.5 (particles that are 10 and 2.5 micrometers in size), which regulate particulate matter, control BC emissions indirectly. Use of low-sulfur fuel, high-efficiency engines, and particulate filters can reduce emissions from diesel combustion, which is used for ships, power generators, and transportation, agricultural, and construction vehicles. Reduction and control of forest fires and agricultural burning can reduce BC emissions from biomass. Technology upgrades and fuel switching from coal to natural gas or renewables can reduce BC emissions from coal burning. Using more efficient stoves and furnaces can reduce emissions from burning solid fuels in developing countries. The Global Alliance for Clean Cookstoves, which seeks to increase usage of more efficient cookstoves in developing country households, acknowledges both the health and climate change implications of inefficient burning of biomass, particularly as they relate to BC emissions.

Internationally, there is a policy gap for regulating BC emissions. There is some discussion under the Convention on Long Range Transboundary Air Pollution that BC be included under the Protocol to Abate Acidification, Eutrophication, and Ground-Level Ozone (Gothenburg Protocol). The Arctic Council, an intergovernmental body that facilitates discussion and decisions among the eight Arctic nations, established a task force to determine the effect of short-lived climate forcers, including BC, on Arctic warming and identify technical needs for mitigation. In 2009, the United States committed $5 million toward international cooperation on reducing BC emissions in and around the Arctic.

Drift Ice

In the world’s polar regions, ice that floats on the water’s surface is termed drift ice. Drift ice is named for its tendency to be carried by wind and currents. The Arctic and Antarctic ice packs (drift ice that is forced into a single mass) account for the majority of the Earth’s drift ice. Research has shown that increased water and air temperatures are causing this ice to melt. The extent of this ice depletion by climate change is unknown, and the long-term impact on ice-dependent species is not clear.

Drift ice plays a critical role in both climate and ecosystem habitats. The ice originates from the freezing of seawater and varies greatly in size. The extent of regions that are covered in drift ice (sea ice) during the past 30 years has significantly decreased. Current climate models predict a continual decrease in sea ice in the foreseeable future, which will likely have a significant impact on the Earth’s albedo, or its potential reflectivity of the sun’s energy. With decreasing ice and, more importantly, snow-covered ice, the albedo of the Earth is decreasing, whereby the amount of sun energy that is absorbed at the surface is increasing. Research has shown that decreased albedo will increase average water and air temperatures, similar to the greenhouse effect discussed in climate change models.

Annual and seasonal variations in any ice formations are well known. The annual fluctuation in Arctic ice ranges from 2 to 5 million sq. mi. (7 to 15 million sq. km) from the end of summer melt to its peak at the end of winter, respectively. The sea and drift ice area surrounding the Antarctic continent, similarly, ranges from 1 to 6 million sq. mi. (3 to 18 million sq. km) during the same period. Seasonal ice can range in thickness from 3 to 6 ft. (1 to 2 m) compared to the typically much thicker “permanent” ice that does not melt during the summer.

Impact on Species, Livelihoods, and Oceans 

Drift ice is a key contributor to local and regional food webs. Changes in ice densities impact microorganisms that are dependent on the ice for nutrients and shelter. Ice algae are the primary producers in ice-associated food webs. As primary producers, they are critical to the survival of all higher-level organisms. Ice habitats are also critical for the juvenile life stages of many microorganisms, such as zooplankton, that are dependent on these algal and bacterial populations as food. Fish seek shelter under the drift ice and feast on the abundant zooplankton. Some of the polar regions’ most sensitive macrofauna, including birds, seals, penguins, and polar bears, are dependent on this floating ice as platforms for rest, hunting, and a source of food.

Indigenous peoples of the Arctic are dependent on drift ice and sea ice for subsistence hunting of whales, seals, and fish. Decreases in and thinning of drift ice because of the climate-warming trend reduce the annual window that these groups have available for hunting. In addition, the populations of macrofauna are declining because of the limited sea ice. Those that survive spend less time in areas that are readily accessible to hunters, concomitantly decreasing the opportunity for a successful hunt that would feed indigenous families. These decreases in drift ice may prove to be beneficial to some indigenous peoples, however, with the opening of channels for new sea routes and future economic benefits with increased navigation and potential for trade. In either case, the lifestyles of indigenous peoples will be altered.

From a global climate perspective, melting of drift ice is likely to have significant impacts on ocean circulation patterns. Ocean circulation is driven by density differences of the water (thermohaline circulation). As ocean surface waters freeze, salt from that water is transferred to the surrounding waters, increasing its salinity (drift ice has very low salt content). The drift ice is then moved by winds and currents to far-reaching locales, contributing freshwater ice melt to these new areas.

These fluxes in ocean salinity will have far-reaching impacts on food webs at and well away from the polar regions, as nearly all organisms have a low salinity range tolerance. Salinity variation is not the only effect of increasing ice melt. If the oceans change from being primarily ice-covered to having more open waters, the productivity (phytoplankton) of the affected regions will increase dramatically, altering the oxygen and nutrients available for other organisms and shifting the food-web structure (i.e., ice algae would disappear). Regional macrofauna may be forced to move to new regions, as drift ice is no longer present, or their populations may simply become extinct.

Research has found that the rate at which drift ice is moving is also increasing. Some suggest significant increases in the movement of ice out of the Arctic regions, up to a 70 percent increase annually, likely because of the thinning of the ice (decreased overall ice mass). Recent data analyses suggest similar trends in the Antarctic, with a net ice export of about 11,500 sq. mi. (30,000 sq. km) per year from the Ross Sea alone. Tracking changes in drift ice has become an important focus of oceanic research in recent years, including new modeling techniques. Ice forecasting systems, such as those employed by the Naval Research Laboratory (NRL), are used to study changes in ice thickness, movement, and stability. New highresolution systems are = coupled with the forecast system already in place to better track changes in drift ice. These technologies will allow scientists to better predict the long-term effects that changes in drift ice will have, both regionally and globally.