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Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner. Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise and longer, more intense heat waves. Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time. Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century. Future effects Temperatures will continue to rise

Greenhouse Gases The most common and most important greenhouse gases are carbon dioxide, methane and nitrous oxide. Black carbon is also a potent warmer, although not a greenhouse gas. Carbon dioxide (CO2) This greenhouse gas is present in relatively low concentrations in the atmosphere; prior to the Industrial Revolution, it made up about 0.03 percent of the atmosphere. Despite its low levels, CO2 makes up about 30 percent of the greenhouse gases naturally found in the atmosphere and it is the major driver of climate change. There are currently approximately 3 trillion metric tons of CO2 in the atmosphere; this is 37 percent higher than the level prior to the Industrial Revolution. Natural sources of carbon dioxide include rotting plant and animal matter, forest fires and volcanoes. Methane (CH4) Methane is a very strong greenhouse gas. There is, however, around 220 times less methane than carbon dioxide in the atmosphere, so overall carbon dioxide has a far greater effect in the atmosphere.

World of Change: Global Temperatures : Feature Articles The world is getting warmer. Whether the cause is human activity or natural variability—and the preponderance of evidence says it’s humans—thermometer readings all around the world have risen steadily since the beginning of the Industrial Revolution. (Click on dates above to step through the decades.) According to an ongoing temperature analysis conducted by scientists at NASA’s Goddard Institute for Space Studies (GISS) and shown in this series of maps, the average global temperature on Earth has increased by about 0.8°Celsius (1.4°Fahrenheit) since 1880. But why should we care about one degree of warming? The global temperature record represents an average over the entire surface of the planet. A one-degree global change is significant because it takes a vast amount of heat to warm all the oceans, atmosphere, and land by that much. The maps above show temperature anomalies, or changes, not absolute temperature. References Hansen, J., R.

Global Warming : Feature Articles Throughout its long history, Earth has warmed and cooled time and again. Climate has changed when the planet received more or less sunlight due to subtle shifts in its orbit, as the atmosphere or surface changed, or when the Sun’s energy varied. But in the past century, another force has started to influence Earth’s climate: humanity How does this warming compare to previous changes in Earth’s climate? What is Global Warming? Global warming is the unusually rapid increase in Earth’s average surface temperature over the past century primarily due to the greenhouse gases released as people burn fossil fuels. Despite ups and downs from year to year, global average surface temperature is rising. Earth’s natural greenhouse effect Earth’s temperature begins with the Sun. As the rocks, the air, and the seas warm, they radiate “heat” energy (thermal infrared radiation). This absorption and radiation of heat by the atmosphere—the natural greenhouse effect—is beneficial for life on Earth.

Glossary of climate change acronyms Assigned amount unit (AAU) A Kyoto Protocol unit equal to 1 metric tonne of CO2 equivalent. Each Annex I Party issues AAUs up to the level of its assigned amount, established pursuant to Article 3, paragraphs 7 and 8, of the Kyoto Protocol. Assigned amount units may be exchanged through emissions trading. Abatement Refers to reducing the degree or intensity of greenhouse-gas emissions. Accession An act whereby a State becomes a Party to a treaty already negotiated and signed by other States; has the same legal effect as ratification. Activities implemented jointly (AIJ) Activities carried out under the Convention to mitigate climate change through partnerships between an investor from a developed country and a counterpart in a host country under a pilot phase that ended in the year 2000. Adaptation Adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities. top CFC Chlorofluorocarbon.

Global Warming : Feature Articles Earth has experienced climate change in the past without help from humanity. We know about past climates because of evidence left in tree rings, layers of ice in glaciers, ocean sediments, coral reefs, and layers of sedimentary rocks. For example, bubbles of air in glacial ice trap tiny samples of Earth’s atmosphere, giving scientists a history of greenhouse gases that stretches back more than 800,000 years. The chemical make-up of the ice provides clues to the average global temperature. See the Earth Observatory’s series Paleoclimatology for details about how scientists study past climates. Glacial ice and air bubbles trapped in it (top) preserve an 800,000-year record of temperature & carbon dioxide. Using this ancient evidence, scientists have built a record of Earth’s past climates, or “paleoclimates.” As the Earth moved out of ice ages over the past million years, the global temperature rose a total of 4 to 7 degrees Celsius over about 5,000 years.

Growth in emission transfers via international trade from 1990 to 2008 Author Affiliations Edited by William C. Clark, Harvard University, Cambridge, MA, and approved March 29, 2011 (received for review May 12, 2010) Abstract Despite the emergence of regional climate policies, growth in global CO2 emissions has remained strong. Footnotes Author contributions: G.P.P., J.C.M., and C.L.W. designed research; G.P.P., J.C.M., and C.L.W. performed research; G.P.P., J.C.M., C.L.W., and O.E. analyzed data; and G.P.P., J.C.M., C.L.W., and O.E. wrote the paper. Freely available online through the PNAS open access option.