Facts about climate change

The Earth's climate has changed significantly over the last century. Scientists have found irrefutable evidence of global warming. As scientists study this evidence and use the information to build computer models, their goal is to be able to better understand how humans are not only affecting the Earth's climate today, but also how they will in the future. The many things they do know about climate change include:

• Current CO2 levels are higher than anytime in the last 420,000 years.

• The Earth's global temperature has increased by 1°F (0.6°C) over the 1900s. Some areas have increased more than 3.3°F (2°C).

• The warmest year on record was 2006. The hottest years on record have all taken place within the last decade.

• Some scientists have predicted that greenhouse gas concentrations could rise as much as 950 ppm by the year 2100 (an increase of 670 ppm).

• Glacier National Park in Montana has had 110 glaciers completely disappear over the last 150 years. If the warming continues, the park could lose all of its glaciers in the next few decades.

• In 2003, a heat wave caused 35,000 people to die in Europe.

• Scientists predict sea levels will rise up to 20 feet (6 m) by the year 2150.

• The 2005 Atlantic hurricane season was the most active and destructive ever recorded.

Source: TheClimateGroup.org the Earth's physical processes. Due to the complexities of the climate system, however, much research still needs to be done.

We must increase our knowledge of the global carbon cycle. The carbon cycle is complex, with many variables and relationships, both direct and indirect. Issues such as how the carbon reservoirs and carbon exchanges within the Earth operate, how carbon cycles through various components of the system, how long it resides in each component, how it is best managed from the human side of the cycle, and a better understanding of its long-term interactions with other components of the Earth's systems, such as the global water cycle, all need further research.

In order to further understanding of climate variability and the effects of global warming, it is also necessary to better understand the global water cycle. By understanding the intricate components of the water cycle, scientists will be able to comprehend its complexities (it involves chemical, physical, and biological processes that play a role in global warming and climate change). A better understanding will enable better modeling techniques, which will lead to better management strategies.

Jennifer Morgan, director of the World Wildlife Fund Climate Change Programme, says that "If we act now, it we address emissions now, we can avoid the worst case scenarios in the future. If it were too late, we would just work on adapting to climate change. We do some of that: we look at how we can make habitats more resilient, how you can extend protected areas, so that species can move. But the main goal for the world must be to cut down the emission of gas that pollutes the atmosphere and destroys the climate."

It is not too late to make a difference; to leave a livable world for future generations. While we will have to adapt to a certain degree to the damage that has already been done, much damage can be prevented by changing energy sources and lifestyle habits now. Planning and changing now while looking ahead will provide the key to a brighter tomorrow.

chronology ca.1400-1850

1800-70 1824



1894 1913-14



Little Ice Age covers the Earth with record cold, large glaciers, and snow. There is widespread disease, starvation, and death.

The levels of CO2 in the atmosphere are 290 ppm.

Jean-Baptiste Joseph Fourier, a French mathematician and physicist, calculates that the Earth would be much colder without its protective atmosphere.

Jean-Baptiste Joseph Fourier presents his theory about the Earth's warming. At this time many believe warming is a positive thing.

John Tyndall, an Irish physicist, discovers that some gases exist in the atmosphere that block infrared radiation. He presents the concept that changes in the concentration of atmospheric gases could cause the climate to change.

Beginning of the industrial pollution of the environment.

Svante Arrhenius discovers the greenhouse effect and predicts that the Earth's atmosphere will continue to warm. He predicts that the atmosphere will not reach dangerous levels for thousands of years, so his theory is not received with any urgency.

Texas and the Persian Gulf bring productive oil wells into operation, which begins the world's dependency on a relatively inexpensive form of energy.

The worst dust storm of the dust bowl occurs in the United States on what historians would later call Black Sunday. Dust storms are a product of drought and soil erosion.

The U.S. Office of Naval Research begins supporting many fields of science, including those that deal with climate change issues.

1949-50 Guy S. Callendar, a British steam engineer and inventor, propounds the theory that the greenhouse effect is linked to human actions and will cause problems. No one takes him too seriously, but scientists do begin to develop new ways to measure climate.

1950-70 Technological developments enable increased awareness about global warming and the enhanced greenhouse effect. Studies confirm a steadily rising CO2 level. The public begins to notice and becomes concerned with air pollution issues.

1958 U.S. scientist Charles David Keeling of the Scripps Institution of Oceanography detects a yearly rise in atmospheric CO2. He begins collecting continuous CO2 readings at an observatory on Mauna Loa, Hawaii. The results became known as the famous Keeling Curve.

1963 Studies show that water vapor plays a significant part in making the climate sensitive to changes in CO2 levels.

1968 Studies reveal the potential collapse of the Antarctic ice sheet, which would raise sea levels to dangerous heights, causing damage to places worldwide.

1972 Studies with ice cores reveal large climate shifts in the past.

1974 Significant drought and other unusual weather phenomenon over the past two years cause increased concern about climate change not only among scientists but with the public as a whole.

1976 Deforestation and other impacts on the ecosystem start to receive attention as major issues in the future of the world's climate.

1977 The scientific community begins focusing on global warming as a serious threat needing to be addressed within the next century.

1979 The World Climate Research Programme is launched to coordinate international research on global warming and climate change.

1982 Greenland ice cores show significant temperature oscillations over the past century.

1983 The greenhouse effect and related issues get pushed into the political arena through reports from the U.S. National Academy of Sciences and the Environmental Protection Agency.

1984-90 The media begins to make global warming and its enhanced greenhouse effect a common topic among Americans. Many critics emerge.

1987 An ice core from Antarctica analyzed by French and Russian scientists reveals an extremely close correlation between CO2 and temperature going back more than 100,000 years.

1988 The United Nations set up a scientific authority to review the evidence on global warming. It is called the Intergovernmental Panel on Climate Change (IPCC) and consists of 2,500 scientists from countries around the world.

1989 The first IPCC report says that levels of human-made greenhouse gases are steadily increasing in the atmosphere and predicts that they will cause global warming.

1990 An appeal signed by 49 Nobel prizewinners and 700 members of the National Academy of Sciences states, "There is broad agreement within the scientific community that amplification of the Earth's natural greenhouse effect by the buildup of various gases introduced by human activity has the potential to produce dramatic changes in climate . . . Only by taking action now can we insure that future generations will not be put at risk."

1992 The United Nations Conference on Environment and

Development (UNCED), known informally as the Earth Summit, begins on June 3 in Rio de Janeiro, Brazil. It results in the United Nations Framework Convention on Climate Change, Agenda 21, the Rio Declaration on Environment and Development Statement of Forest Principles, and the United Nations Convention on Biological Diversity.

1993 Greenland ice cores suggest that significant climate change can occur within one decade.

1995 The second IPCC report is issued and concludes there is a human-caused component to the greenhouse effect warming. The consensus is that serious warming is likely in the coming century. Reports on the breaking up of Antarctic ice sheets and other signs of warming in the polar regions are now beginning to catch the public's attention.

1997 The third conference of the parties to the Framework Convention on Climate Change is held in Kyoto, Japan. Adopted on December 11, a document called the Kyoto Protocol commits its signatories to reduce emissions of greenhouse gases.

2000 Climatologists label the 1990s the hottest decade on record.

2001 The IPPC's third report states that the evidence for anthropogenic global warming is incontrovertible, but that its effects on climate are still difficult to pin down. President Bush declares scientific uncertainty too great to justify Kyoto Protocol's targets.

The United States Global Change Research Program releases the findings of the National Assessment of the Potential Consequences of Climate Variability and Change. The assessment finds that temperatures in the United States will rise by 5 to 9°F (3-5°C) over the next century and predicts increases in both very wet (flooding) and very dry (drought) conditions. Many ecosystems are vulnerable to climate change. Water supply for human consumption and irrigation is at risk due to increased probability of drought, reduced snow pack, and increased risk of flooding. Sea-level rise and storm surges will most likely damage coastal infrastructure.


Second hottest year on record.

Heavy rains cause disastrous flooding in Central Europe leading to more than 100 deaths and more than $30 billion in damage. Extreme drought in many parts of the world (Africa, India, Australia, and the United States) results in thousands of deaths and significant crop damage. President Bush calls for 10 more years of research on climate change to clear up remaining uncertainties and proposes only voluntary measures to mitigate climate change until 2012.

2003 U.S. senators John McCain and Joseph Lieberman introduce a bipartisan bill to reduce emissions of greenhouse gases nationwide via a greenhouse gas emission cap and trade program.

Scientific observations raise concern that the collapse of ice sheets in Antarctica and Greenland can raise sea levels faster than previously thought.

A deadly summer heat wave in Europe convinces many in Europe of the urgency of controlling global warming but does not equally capture the attention of those living in the United States.

International Energy Agency (IEA) identifies China as the world's second largest carbon emitter because of their increased use of fossil fuels.

The level of CO2 in the atmosphere reaches 382 ppm.

2004 Books and movies feature global warming.

2005 Kyoto Protocol takes effect on February 16. In addition, global warming is a topic at the G8 summit in Gleneagles, Scotland, where country leaders in attendance recognize climate change as a serious, long-term challenge.

Hurricane Katrina forces the U.S. public to face the issue of global warming.

2006 Former U.S. vice president Al Gore's An Inconvenient Truth draws attention to global warming in the United States.

Sir Nicholas Stern, former World Bank economist, reports that global warming will cost up to 20 percent of worldwide gross domestic product if nothing is done about it now.

2007 IPCC's fourth assessment report says glacial shrinkage, ice loss, and permafrost retreat are all signs that climate change is underway now. They predict a higher risk of drought, floods, and more powerful storms during the next 100 years. As a result, hunger, homelessness, and disease will increase. The atmosphere may warm 1.8 to 4.0°C and sea levels may rise 7 to 23 inches (18 to 59 cm) by the year 2100.

Al Gore and the IPCC share the Nobel Peace Prize for their efforts to bring the critical issues of global warming to the world's attention.

2008 The price of oil reached and surpassed $100 per barrel, leaving some countries paying more than $10 per gallon.

Energy Star appliance sales have nearly doubled. Energy Star is a U.S. government-backed program helping businesses and individuals protect the environment through superior energy efficiency.

U.S. wind energy capacity reaches 10,000 megawatts, which is enough to power 2.5 million homes.

2009 President Obama takes office and vows to address the issue of global warming and climate change by allowing individual states to move forward in controlling greenhouse gas emissions. As a result, American automakers can prepare for the future and build cars of tomorrow and reduce the country's dependence on foreign oil. Perhaps these measures will help restore national security and the health of the planet, and the U.S. government will no longer ignore the scientific facts.

The year 2009 will be a crucial year in the effort to address climate change. The meeting on December 7-18 in Copenhagen, Denmark, of the UN Climate Change Conference promises to shape an effective response to climate change. The snapping of an ice bridge in April 2009 linking the Wilkins Ice Shelf (the size of Jamaica) to Antarctic islands could cause the ice shelf to break away, the latest indication that there is no time to lose in addressing global warming.

glossary adaptation An adjustment in natural or human systems to a new or changing environment. Adaptation to climate change refers to adjustments in natural or human systems in response to actual or expected climatic changes. aerosols Tiny bits of liquid or solid matter suspended in air. They come from natural sources such as erupting volcanoes and from waste gases emitted from automobiles, factories, and power plants. By reflecting sunlight, aerosols cool the climate and offset some of the warming caused by greenhouse gases.

albedo The relative reflectivity of a surface. A surface with high albedo reflects most of the light that shines on it and absorbs very little energy; a surface with a low albedo absorbs most of the light energy that shines on it and reflects very little. anthropogenic Made by people or resulting from human activities. This term is usually used in the context of emissions that are produced as a result of human activities. atmosphere The thin layer of gases that surround the Earth and allow living organisms to breathe. It reaches 400 miles (644 km) above the surface, but 80 percent is concentrated in the troposphere—the lower seven miles (11 km) above the Earth's surface. biodiversity Different plant and animal species. biomass Plant material that can be used for fuel. bleaching (coral) The loss of algae from corals that causes the corals to turn white. This is one of the results of global warming and signifies a dieoff of unhealthy coral.

carbon A naturally abundant nonmetallic element that occurs in many inorganic and in all organic compounds. carbon cycle A biogeochemical cycle in which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of Earth.

carbon dioxide A colorless, odorless gas that passes out of the lungs during respiration. It is the primary greenhouse gas and causes the greatest amount of global warming.

carbon sink An area where large quantities of carbon are built up in the wood of trees, in calcium carbonate rocks, in animal species, in the ocean, or any other place where carbon is stored. These places act as reservoirs, keeping carbon out of the atmosphere.

chlorofluorocarbons (CFCs) Gases that were once widely used as coolants in refrigerators and air conditioners, as foaming agents for insulation and food packaging, and as cleaning agents in certain industries. They are long-lasting compounds that absorb heat energy more effectively than CO2. When they enter the upper atmosphere, they destroy ozone (which protects life on Earth from harmful ultraviolet radiation). An international treaty calls for all production of CFCs to stop by the year 2010.

climate The usual pattern of weather that is averaged over a long period of time.

climate feedback An interaction between processes in the climate system is called a climate feedback, when the result of an initial process triggers changes in a second process that in turn influences the initial one. A positive feedback intensifies the original process, and a negative feedback reduces it.

climate model A quantitative way of representing the interactions of the atmosphere, oceans, land surface, and ice. Models can range from relatively simple to extremely complicated.

climatologist A scientist who studies the climate.

concentration The amount of a component in a given area or volume. In global warming, it is a measurement of how much of a particular gas is in the atmosphere compared to all of the gases in the atmosphere.

condense The process that changes a gas into a liquid.

Coriolis force The effect caused by the spherical shape of the Earth that results in winds veering to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

cyclone A large-scale, atmospheric wind and pressure system characterized by low pressure at the center and circular wind motion, counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere. deflection The angle formed by the line of sight to the target and the line of sight to the point at which an object is aimed. Because of the Earth's rotation, an object set into motion through the atmosphere will appear to deflect, or curve, from its beginning point to ending point in the path of travel because the Earth has moved underneath it while it was airborne. deforestation The large-scale cutting of trees from a forested area, often leaving bare areas susceptible to erosion. doldrums A belt of calms and light winds north of the equator between the northern and southern trade winds in the Atlantic and Pacific Oceans.

downwelling A downward current of surface water in the ocean, usually caused by differences in the density of seawater. ecosystem A community of interacting organisms and their physical environment.

El Niño A cyclic weather event in which the waters of the eastern Pacific Ocean off the coast of South America become much warmer than normal and disturb weather patterns across the region. Every few years, the temperature of the western Pacific rises several degrees above that of waters to the east. The warmer water moves eastward, causing shifts in ocean currents, jet stream winds, and weather in both the Northern and Southern Hemispheres.

emissions The release of a substance (usually a gas when referring to the subject of climate change) into the atmosphere. emissivity The ability of a surface to emit radiant energy compared to that of a black body at the same temperature and with the same area.

evaporation The process by which a liquid, such as water, is changed to a gas.

feedback A change caused by a process that, in turn, may influence that process. Some changes caused by global warming may hasten the process of warming (positive feedback); some may slow warming (negative feedback).

forcings Mechanisms that disrupt the global energy balance between incoming energy from the Sun and outgoing heat from the Earth. By altering the global energy balance, such mechanisms force the climate to change. Today, anthropogenic greenhouse gases added to the atmosphere are forcing climate to change. fossil fuel An energy source made from coal, oil, or natural gas. The burning of fossil fuels is one of the chief causes of global warming. glacier A mass of ice formed by the buildup of snow over hundreds and thousands of years. global dimming A reduction in the amount of the Sun's electromagnetic energy reaching the Earth's surface due to its blockage by particulate matter, clouds, and other opaque materials in the atmosphere.

global warming An increase in the temperature of the Earth's atmosphere, caused by the buildup of greenhouse gases. This is also referred to as the enhanced greenhouse effect caused by humans. global warming potential (GWP) The cumulative radiative forcing effects of a gas over a specified time resulting from the emission of a unit mass of gas relative to a reference gas (usually CO2). great ocean conveyor belt A global current system in the ocean that transports heat from one area to another. greenhouse effect The natural trapping of heat energy by gases present in the atmosphere, such as CO2, methane, and water vapor. The trapped heat is then emitted as heat back to the Earth.

greenhouse gas A gas that traps heat in the atmosphere and keeps the

Earth warm enough to allow life to exist. Gulf Stream A warm current that flows from the Gulf of Mexico across the Atlantic Ocean to northern Europe. It is largely responsible for Europe's milder climate. halogens Any of a group of five nonmetallic elements with similar properties. The halogens are fluorine, chlorine, bromine, iodine, and astatine. Because they are missing an electron from their outermost shell, they react readily with most metals to form salts.

hydrologic cycle The natural sequence through which water passes into the atmosphere as water vapor, precipitates to earth in liquid or solid form, and ultimately returns to the atmosphere through evaporation.

Industrial Revolution The period during which industry developed rapidly as a result of advances in technology. This took place in Britain during the late 18th and early 19th centuries.

infrared The invisible heat radiation that is emitted by the Sun and by virtually every warm substance or object on Earth. IPCC Intergovernmental Panel on Climate Change. This is an organization consisting of 2,500 scientists that assesses information in the scientific and technical literature related to the issue of climate change. The IPCC was established jointly by the United Nations Environment Programme and the World Meteorological Organization in 1988. jet stream A strong ribbon of horizontal wind that is found about 6 to 10 miles (10-16 km) above the ground in the area between the troposphere, the lower layer of the atmosphere, and the stratosphere above it.

Keeling Curve A famous curve showing increasing CO2 concentrations in the atmosphere, which was set up by Dr. Charles David Keeling of Scripps Institution of Oceanography at Mauna Loa in Hawaii, it illustrates the steady rise in CO2 concentrations since 1958.

land breeze Opposite of a sea breeze, a breeze that blows from the land toward open water. land use The management practice of a certain land cover type, forest, arable land, grassland, urban land, and wilderness. land use change An alteration of the management practice on a certain land cover type. Land use changes may influence climate systems because they influence evapotranspiration and sources and sinks of greenhouse gases, i.e., removing a forest to build a city. mass wasting The downslope movement of rock and regolith near the

Earth's surface mainly due to the force of gravity. Maunder minimum The period of reduced solar activity lasting through the 1600s and 1700s. mesosphere The layer of the atmosphere that lies on top of the stratosphere and runs upward to about 50 miles (80 km).

methane A colorless, odorless, flammable gas that is the major ingredient of natural gas. Methane is produced wherever decay occurs and little or no oxygen is present. monsoon Heavy rains that occur at the same time each year. mountain breeze It is formed at night by the radiational cooling along mountainsides. As the slopes become colder than the surrounding atmosphere, the lower levels of air cool and drain to the lowest point of the terrain. It may reach several hundred feet in depth and, in extreme cases, attain speeds of 57.5 miles per hour (50 knots) or greater. It blows in the opposite direction of a valley breeze.

nitrogen As a gas, nitrogen takes up 80 percent of the volume of the Earth's atmosphere. It is also an element in substances such as fertilizer.

nitrous oxide A heat-absorbing gas in the Earth's atmosphere. Nitrous oxide is emitted from nitrogen-based fertilizers.

nuclear power The electricity produced by a process that begins with the splitting apart of uranium atoms, yielding great amounts of heat energy.

ocean ridges An area under the ocean where the Earth's crust is pulling apart, allowing new lava to emerge on the ocean floor, harden, and become new crust in the plate tectonic process.

ozone A molecule that consists of three oxygen atoms. Ozone is present in small amounts in the Earth's atmosphere at 14 to 19 miles (23-31 km) above the Earth's surface. A layer of ozone makes life possible by shielding the Earth's surface from most harmful ultraviolet rays. In the lower atmosphere, ozone emitted from auto exhausts and factories is an air pollutant. paleomagnetism The study of the record of the Earth's magnetic field preserved in various magnetic minerals through time. parts per million (ppm) The number of parts of a chemical found in one million parts of a particular gas, liquid, or solid. permafrost Permanently frozen ground in the Arctic. As global warming increases, this ground is melting. photosynthesis The process by which plants make food using light energy, carbon dioxide, and water.

protocol The terms of a treaty that have been agreed to and signed by all parties.

proxies Methods of determining values such as temperatures and rainfall by using substitutes, which give indirect measurements. Tree rings serve as proxies for determining rainfall abundance. radiation The particles or waves of energy.

renewable Something that can be replaced or regrown, such as trees, or a source of energy that never runs out, such as solar energy, wind energy, or geothermal energy. resources The raw materials from the Earth that are used by humans to make useful things. rotation The movement or path of the Earth, turning on its axis.

satellite Any small object that orbits a larger one. Artificial satellites carry instruments for scientific study and communication. Imagery taken from satellites is used to monitor aspects of global warming such as glacier retreat, ice cap melting, desertification, erosion, hurricane damage, and flooding. Sea surface temperatures and measurements are also obtained from man-made satellites in orbit around the Earth. sea breeze A wind from the sea that develops over land near coasts. It is formed by increasing temperature differences between the land and water that create a pressure minimum over the land due to its relative warmth and forces higher pressure, cooler air from the sea to move inland.

simulation A computer model of a process that is based on actual facts. The model attempts to mimic, or replicate, actual physical processes.

stratosphere The layer of the atmosphere just above the troposphere. It extends 7.5 miles (12 km) to an average of 31 miles (50 km).

temperate An area that has a mild climate and different seasons.

thermal Something that relates to heat.

trace gases Gases found in minute amounts in the atmosphere.

trade winds Winds that blow steadily from east to west and toward the equator. The trade winds are caused by hot air rising at the equator, with cool air moving in to take its place from the north and from the south. The winds are deflected westward because of the Earth's west-to-east rotation.

tropical A region that is hot and often wet (humid). These areas are located around the Earth's equator. tropical depression A cyclone in a tropical region that is more intense than a disturbance but less than a storm, with wind speeds of 38 mph (61 km/h) or less.

tropical disturbance A very weak tropical cyclone. tropical storm A cyclonic storm having winds ranging from approximately 30 to 75 miles (48-121 kilometers) per hour. troposphere The bottom layer of the atmosphere, rising from sea level up to an average of about 7.5 miles (12 km).

tundra A vast treeless plain in the Arctic with a marshy surface covering a permafrost layer. ultraviolet radiation A portion of the Sun's electromagnetic spectrum, consisting of very short wavelengths and high energy. The atmosphere's ozone layer protects life on Earth from the damaging effects from UV radiation. upwelling The process by which warm, less-dense surface water is drawn away from along a shore by offshore currents and replaced by cold, denser water brought up from the subsurface. valley breeze An anabatic wind, it is formed during the day by the heating of the valley floor. As the ground becomes warmer than the surrounding atmosphere, the lower levels of air heat and rise, flowing up the mountainsides. It blows in the opposite direction of a mountain breeze.

visible light The wavelengths of the Sun's electromagnetic spectrum that humans can see; it falls in the wavelength range of 400 to 700 nm.

weather The conditions of the atmosphere at a particular time and place. Weather includes such measurements as temperature, precipitation, air pressure, and wind speed and direction.

weathering The progression of breaking down rocks and natural materials on the Earth's surface through physical and chemical processes.

westerlies A semipermanent belt of westerly winds that prevails at latitudes lying between the tropical and polar regions of the Earth.

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