Guest HUSSEIN BARAKA Posted March 9, 2008 Report Share Posted March 9, 2008 AL GORE IS STILL IN HIDING SINCE IT WAS PROVEN HE IS A FRAUD. Link to comment Share on other sites More sharing options...
Guest Wild Bill Posted March 9, 2008 Report Share Posted March 9, 2008 AL GORE IS STILL IN HIDING SINCE IT WAS PROVEN HE IS A FRAUD. Who is Al Gore? Did he do something to affect us. Did he work for Haliburton or someone? Link to comment Share on other sites More sharing options...
Guest Guest-Getting Warmer Posted March 9, 2008 Report Share Posted March 9, 2008 Who is Al Gore? Did he do something to affect us. Did he work for Haliburton or someone? Table of Contents How to order printed copies The issue that's heating up Global warming: It’s a phrase we’ve been hearing on weather broadcasts and news reports, in science classrooms and around supper tables since the early 1980s. It’s a vague concept that seems far removed from our everyday lives, something that concerns anonymous scientists digging into polar ice caps thousands of miles away – not us. But global warming and the changes it could cause in world climate should concern us. Wisconsin as we know it could experience drastic change as temperatures inch up globally. © Robert Queen The great majority of scientific research agrees that between now and the middle of the coming century the globe could very well warm up, and the results could significantly alter life in this little corner of the planet we call home. Credible scenarios show Wisconsin could face: wetter winters and drier summers with longer, hotter and more frequent heat waves weather and climate changes that could require farmers to raise different crops dairy cattle beleaguered by heat exhaustion and growing pest populations poor air quality and higher concentrations of ground-level ozone, an air pollutant that causes severe health problems warmer and more shallow river waters – conditions that could hurt populations of cold-water fish like trout denser algae blooms and lower oxygen levels in ponds and lakes more frequent floods, droughts, forest fires and damaging storms changes in tree species that could affect the forestry industry and wildlife populations increases in disease-carrying insect populations All of these potential changes are just that: potential. Because of the intricate interplay of a whole slew of climatic factors, it's difficult to predict what an increase in global temperature might bring. This publication dips into the ocean of global climate change theory, and attempts to fish out the bits pertinent to Wisconsin. Table of Contents The issue that's heating up What is global warming? From global temperature to global climate Wisconsin under the heat lamp Responding to a global threat What can I do? How do scientists study past climate? What is global warming? Historical records indicate the average global temperature increased by 0.5 to1° Fahrenheit (F) between 1890 and 1990. In the next 100 years, scientists predict the temperature may rise another 2 to 6° F. Such increases have occurred previously in Earth’s history, but never over such a short time span. In fact, the average global temperature has risen more in the last century than at any time in the past 10,000 years. What’s causing this warming trend? Scientists agree the answer hinges on the six main human-influenced greenhouse gases in our atmosphere. These gases – carbon dioxide (CO2), methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride – make up about 1% of our atmosphere. They keep our planet warm by trapping the sun’s energy and slowing its escape back into space. This heat-trapping ability is called the greenhouse effect, and it allows us to enjoy an average global temperature of 60° F. If our atmosphere lacked greenhouse gases, the Earth would be a cold gray lump of cosmic matter, and life as we know it would not exist. Since the Industrial Revolution, however, atmospheric concentrations of the most important human-influenced greenhouse gases – CO2, methane and nitrous oxide – have increased at an unnatural rate. In the last 200 years, CO2 levels have risen almost 30%, methane levels have gone up 145%, and nitrous oxide levels have increased by 15%. Gasoline-powered vehicles account for nearly half of Wisconsin's greenhouse gas emissions. © Robert Queen Where are all these "extra" greenhouse gases coming from? Us. Large-scale burning of fossil fuels for industry and motor vehicles, intense agricultural activity, mining, and other human activities pump more and more greenhouse gases into the atmosphere, creating a heightened greenhouse effect that leads to a higher average global temperature – global warming. How do scientists study past climate? If scientists had to rely on written weather records for historical climate information, they would be in trouble. Such records only exist for the last 150 years or so. However, clues in the environment can provide information from thousands of years ago. Ice cores -- Ice in polar regions contains air bubbles trapped thousands of years in the past. Scientists can check the gases in the bubbles and provide a good estimate of the temperature at that time. Also, the thickness of the ice layers gives information about past climates. Tree rings -- Trees can live for centuries, and for each year of their lives they add a ring of growth to their diameter. The width of these rings can give scientists information about climate during that year of growth. Fossils -- The bones of long-dead animals indicate which species lived in certain areas and when they were there. Since each species has a set of food and temperature requirements, scientists can deduce the climate of their time and area. Sediment cores -- A column of sediment from a lake bottom contains pollen grains in each layer. The deeper the layer, the older the sediment. After determining the age of the layers, scientists can study what plants were growing when the sediment was deposited. Archaeological records -- Humans have left their traces throughout the world for ages. How they lived and what they needed to survive can provide important clues about the climates they experienced. Normally, the elements that compose greenhouse gases (carbon, oxygen, nitrogen, etc.) cycle freely through the environment between sources and sinks. Sources release elements to the atmosphere; sinks store them. For example, carbon is stored in most life forms on Earth, including trees; trees are sinks for carbon. When trees are cut down and burned, this stored carbon is released into the atmosphere as carbon dioxide; thus, the burning of trees is a carbon source. For two centuries, we've been releasing greenhouse gases into the atmosphere at unprecedented rates while destroying forests and other natural sinks that could absorb those gases. In our attempts to improve the quality of life, we've created a greenhouse that’s a little too effective. From global temperature to global climate Because of human activities, the average global temperature may become 2 to 6° F warmer by 2100. While the prospect of a few more degrees of warmth may sound appealing to anyone who's endured a Wisconsin winter, it’s important to realize the repercussions of such a change. Consider that during El Nino, which tends to bring with it severe dry spells, storms and other dangerous weather events, average winter temperatures go up by only 0.5° F. There is no longer much dispute over whether an increase in global temperature will affect global climate. Exactly how the climate will change, however, is a topic rife with debate. Researchers use computer models that mimic the Earth’s climate to make educated predictions on what changes global warming may bring. The view they see is daunting: Nearly all regions of the globe would experience higher temperatures, but some, particularly inland areas in northern latitudes like Wisconsin, could get warmer than others. Some regions could become significantly drier while others would get more rain and snow. More frequent and intense floods could drown dairying and other mainstays of Wisconsin's economy. © Robert Queen Altered weather patterns could affect agriculture, forest make-up and wildlife populations. By 2100, ocean levels could rise as much as 3 feet, causing extensive coastal flooding that could disrupt food supplies, damage or destroy human dwellings, and displace millions of people. Extreme weather events like hurricanes, floods, droughts, and forest fires could become more frequent and intense. Local and regional economies as well as human health could suffer. Wisconsin under the heat lamp Because the models scientists use to study climate change are not sufficiently precise to offer specific predictions for an area as small as the state of Wisconsin, the following discussion is taken from predictions for the upper Midwest region. While it’s fairly safe to say that global climate change won’t turn our state into a tropical paradise, scientists agree that it could significantly alter the way we live. Weather and climate Researchers speculate the upper Midwest would generally become warmer and wetter, with the average temperature increasing by about 4° F. The increase doesn’t mean we’d simply up the daily temperature by 4° ; a more likely scenario is that summer heat waves would be longer and hotter, and nighttime winter temperatures wouldn’t sink so low. Precipitation could increase by as much as 10% on average, but much of the increased precipitation could come in the form of intense storms, leading to local flooding and more runoff. Precipitation patterns could also change, with more rain coming in the winter and less in the summer. Less rain in the summer, paired with increased evaporation caused by warmer temperatures, could trigger severe summer droughts. Water resources Wisconsinites treasure our 15,000-plus lakes, and the scores of rivers, streams and wetlands that grace our state. Climate change could have tremendous effects on these waters, including the Great Lakes. As warmer weather raises water temperatures, more algae blooms could clog lakes, endangering aquatic species. © Dale Lang Lake Superior water levels could drop over time by 1 to 1.5 feet, while Lake Michigan levels could fall 3 to 8 feet. Such drops could result from longer and drier summers during which more of the lakes’ waters would be claimed by evaporation. Winters might have less snow and shorter periods of snow cover. Lowered Great Lakes levels could strike a heavy blow to industries like shipping and hydropower generation. Smaller inland lakes could also get shallower, and some ponds and wetlands might disappear altogether, jeopardizing wildlife habitat and our tourism and recreation industries. Finally, groundwater levels could drop significantly, threatening drinking water quality and quantity. Water temperature could also be a problem. Warmer water would encourage algae blooms and other aquatic plant overgrowth in the summer, transforming clear blue waters into a thick, smelly pea soup that turns off boaters, anglers and swimmers, and makes survival difficult for fish and other aquatic species. Cold-water species like trout could decline in number or disappear from their traditional areas altogether. And decreased winter ice cover could disturb both lake ecology and the ice fishing season. Agriculture Should the weather warm significantly, crops like soybeans and corn currently grown in southern Wisconsin might have to be cultivated in northern fields, where thinner soils may not produce abundant harvests. © Robert Queen Anything that affects farming affects the state’s economy. Some researchers predict that under the influences of climate change, southern Wisconsin farms might begin to resemble those in present-day Kansas. Wheat would do well, but the ideal range for corn and soybeans would shift northward, and these crops might not grow as well in the soils of northern Wisconsin. High levels of carbon dioxide in the atmosphere may actually increase crop production, because certain plants can become larger and more productive in a CO2–rich environment. However, gains in crop productivity might be counter-balanced by more frequent and severe droughts, and by more weed, pest and disease problems. Dairy and other livestock farmers might see productivity decline as their herds suffer from heat stress, the feed supply is disrupted (from changing crop yields), and the water supply reduced. Warmer, longer summers might encourage the growth of pest populations that could further stress livestock and spread disease. Forests and wildlife As temperature and precipitation patterns change, habitat ranges for flora and fauna are expected to shift northward. Some species might be able to migrate with their ideal habitat, but others, especially those already endangered, could face extinction. Researchers predict that mixed northern hardwood and oak forests would be transformed to oak savannas and grasslands within 30 to 60 years. Typical northern forests could completely disappear from Wisconsin, along with the eastern hemlock and the sugar maple. Such radical changes in forest makeup could have far-reaching effects on the forestry industry, some types of hunting -- and the very character of our state's landscape. Human health Weather changes could directly affect human health. More frequent and severe heat waves would threaten the elderly – especially those living alone – and people suffering from cardiovascular and respiratory diseases. The U.S. Environmental Protection Agency (EPA) projects that a 3° F warming could almost double heat-related deaths in Milwaukee during a typical summer, from 30 to about 55. Aside from deaths caused directly by heat, climate change poses other health-related threats. A longer, hotter summer, along with increased emissions from power plants trying to keep up with greater air conditioning demands, would likely intensify air pollution problems. This could result in more, and more serious cases of asthma, emphysema and lung disease for Wisconsin residents. Wisconsin’s allergy season could lengthen because some plants would flourish in the extended summer. Warmer weather might also be more hospitable to disease-carrying insects like mosquitoes and ticks, leading to more cases of Lyme disease, tick-borne encephalitis, and possibly even malaria. Finally, more frequent severe weather events like forest fires, floods and dangerous storms could cause injuries and take lives. Responding to a global threat Despite the uncertainty of predicting the effects of climate change, scientists and policy-makers are not sitting idly by. Wisconsin is working with other states and nations to understand climate change and find ways to limit or prevent the disruption and devastation it could cause. The Wisconsin Department of Natural Resources (DNR) has completed several studies showing that the use of energy-efficient technologies could reduce the state’s emissions of greenhouse gases with little or no net cost. One study showed that if Wisconsin adopted improved energy efficiency measures, we could realize a 12.5-million-ton decrease in the growth of greenhouse gas emissions by 2010 (compared to projected levels) and save $490 million in energy expenditures at the same time. Another study predicted that investing in energy efficiency measures could create a $490 million increase in disposable income, a $41 million increase in gross state product, and 8,500 new jobs in 2010. Based on these studies, the Wisconsin DNR created the Wisconsin Climate Change Action Plan. For more information on the studies or the plan, see the following website: www.dnr.state.wi.us/org/aw/air/global/global.htm In 1992, 154 nations and the European Union adopted the United Nations Framework Convention on Climate Change, a voluntary agreement to stabilize greenhouse gas emissions at 1990 levels. In December 1997 at a United Nations meeting in Kyoto, Japan, some industrialized countries went a step further and agreed to the Kyoto Protocol, which requires developed nations to reduce their greenhouse gas emissions to an average of 5 percent below 1990 levels by 2008-2012. Specific reduction commitments vary among nations. If the protocol goes into effect, it will require the U.S. to reduce Greenhouse gas emissions to seven percent below 1990 levels. However, at current rates our nation stands to increase its emissions to 30 percent above 1990 levels by 2010. Our country is already the world’s largest emitter of greenhouse gases, contributing approximately 23 percent of global emissions despite having only 5 percent of the world’s population. What can I do? The solutions to global warming may seem to be out of our hands, but we can take action -- and many of the things we can do to reduce greenhouse gas emissions offer personal benefits as well. Save the planet -- take the bus! © Robert Queen The biggest contribution individuals can make is to use less energy. By tuning cars, insulating homes and using energy-efficient appliances, we can decrease our use of fossil fuels and save money. We can carpool, use public transportation, or walk or bike to our destinations. These activities cut fuel consumption, decrease traffic congestion, decrease emissions of other air pollutants, and may even get our hearts pumping. Finally, we can purchase items with reusable, recyclable, or reduced packaging – all options that help decrease the amount of energy being used to make new packaging. Those willing to invest even more in guarding against climate change have further options. Alternative energy sources like solar and wind power can supply home energy needs. Cars that use propane or natural gas – fuels that burn more cleanly than gasoline – are already on the roads. Hybrid cars, which use electricity from batteries along with gasoline for power, are entering the market. And solar-powered cars, as well as fuel-cell cars powered by hydrogen, may be available within the next 10 years. Responding to the complexities of climate change won't be easy, but the State of Wisconsin has never backed down from a challenge. With cooperation from business, industry and individuals, Wisconsin can continue to serve as a national leader as the global warming issue heats up. Hot stuff For more information on global warming and climate change, peruse the following websites and publications: U.S. Environmental Protection Agency Global Warming www.epa.gov/globalwarming U.S. Global Change Research Program www.usgcrp.gov United Nations Framework Convention on Climate Change www.unfccc.org United Nations Environment Program and the World Meteorological Organization, Common Questions About Climate Change www.unep.org Intergovernmental Panel on Climate Change www.ipcc.ch Consortium for Integrated Resource Planning, Engineering Professional Development, University of Wisconsin, Wisconsin Department of Natural Resources and Leonardo Academy, Inc., The Economic and Greenhouse Gas Emission Impacts of Electric Energy Efficiency Investments: A Wisconsin Case Study. Report 4 of the Wisconsin Greenhouse Gas Emission Reduction Cost Study, February 23, 1998. Intergovernmental Panel on Climate Change, IPCC Second Assessment: Climate Change 1995. Intergovernmental Panel on Climate Change, The Regional Impacts of Climate Change: An Assessment of Vulnerability, 1998. Office of Science and Technology Policy, Climate Change: State of Knowledge, October 1997. United States Department of State, U.S. Climate Action Report, ISBN 0-16-045214-7, July 1997. U.S. Environmental Protection Agency, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-1997, EPA 236-R-99-003, April 1999. Wisconsin Department of Natural Resources, Global Climate Change: Management Strategies for Wisconsin, Publication Number AM-066-91, December 1991. Wisconsin Department of Natural Resources, University of Wisconsin Consortium for Integrated Resource Planning, and Leonardo Academy, Inc., Wisconsin Greenhouse Gas Emission Reduction Cost Study, Report 3: Emission Reduction Cost Analysis, Publication Number AM-269-98, February 1998. Wisconsin Department of Natural Resources and the Wisconsin Climate Change Committee, Wisconsin Climate Change Action Plan: Framework for Climate Change Action, Publication Number AM 271-98, May 1998. To order printed copies of "Warming trends" send an email message to Anne Urbanski requesting publication number AM-303-00. Include your name, address and number of copies desired. ---------------------------------------------------------------------------------------------------------- Link to comment Share on other sites More sharing options...
Guest Global Posted March 9, 2008 Report Share Posted March 9, 2008 Please do more than stick your head out your front door and declare Global Warming does not exist. You sound like the crew from Faux News DOC > NOAA > NESDIS > NCDC Search Field: National Oceanic and Atmospheric Administration Global Warming Frequently Asked Questions Please note that this page is in the process of being updated with new information from the Fourth IPCC Assessment and other recent work. Please check back frequently for changes. Introduction What is the greenhouse effect, and is it affecting our climate? Are greenhouse gases increasing? Is the climate warming? Are El Niños related to Global Warming? Is the hydrological cycle (evaporation and precipitation) changing? Is the atmospheric/oceanic circulation changing? Is the climate becoming more variable or extreme? How important are these changes in a longer-term context? Is sea level rising? Can the observed changes be explained by natural variability? What about the future? Additional Information -------------------------------------------------------------------------------- All figures linked from this page with the exception of global surface temperatures are from the IPCC 2001 report 'Climate Change 2001: The Scientific Basis'. -------------------------------------------------------------------------------- Introduction This page is based on a brief synopsis of the 2001 report by the Intergovernmental Panel on Climate Change, and the National Research Council's 2001 report Climate Change Science: An Analysis of Some Key Questions, as well as NCDC's own data resources. It was prepared by David Easterling and Tom Karl, National Climatic Data Center, Asheville, N.C. 28801. One of the most hotly debated topics on Earth is the issue of climate change, and the National Environmental Satellite, Data, and Information Service (NESDIS) data centers are central to answering some of the most pressing global change questions that remain unresolved. The National Climatic Data Center contains the instrumental records that can precisely define the nature of climatic fluctuations at time scales of a up to a century. Among the diverse kinds of data platforms whose data contribute to NCDC's armamentarium are: Ships, buoys, weather stations, balloons, satellites, and aircraft. The National Oceanographic Data Center contains the subsurface data which reveal the ways that heat is distributed and redistributed over the planet. Knowing how these systems are changing and how they have changed in the past is crucial to understanding how they will change in the future. And, for climate information that extends from hundreds to thousands of years, the paleoclimatology program, also at the National Climatic Data Center, helps to provide longer term perspectives. Internationally, the Intergovernmental Panel on Climate Change (IPCC), under the auspices of the United Nations (UN), World Meteorological Organization (WMO), and the United Nations Environment Program (UNEP), is the most senior and authoritative body providing scientific advice to global policy makers. The IPCC met in full session in 1990, 1995 and in 2001. They address issues such as the buildup of greenhouse gases, evidence, attribution, and prediction of climate change, impacts of climate change, and policy options. Listed below are a number of questions commonly addressed to climate scientists, and brief replies (based on IPCC reports and other research) in common, understandable language. This list will be periodically updated, as new scientific evidence comes to light. -------------------------------------------------------------------------------- What is the greenhouse effect, and is it affecting our climate? The greenhouse effect is unquestionably real and helps to regulate the temperature of our planet. It is essential for life on Earth and is one of Earth's natural processes. It is the result of heat absorption by certain gases in the atmosphere (called greenhouse gases because they effectively 'trap' heat in the lower atmosphere) and re-radiation downward of some of that heat. Water vapor is the most abundant greenhouse gas, followed by carbon dioxide and other trace gases. Without a natural greenhouse effect, the temperature of the Earth would be about zero degrees F (-18°C) instead of its present 57°F (14°C). So, the concern is not with the fact that we have a greenhouse effect, but whether human activities are leading to an enhancement of the greenhouse effect. -------------------------------------------------------------------------------- Are greenhouse gases increasing? Human activity has been increasing the concentration of greenhouse gases in the atmosphere (mostly carbon dioxide from combustion of coal, oil, and gas; plus a few other trace gases). There is no scientific debate on this point. Pre-industrial levels of carbon dioxide (prior to the start of the Industrial Revolution) were about 280 parts per million by volume (ppmv), and current levels are about 370 ppmv. The concentration of CO2 in our atmosphere today, has not been exceeded in the last 420,000 years, and likely not in the last 20 million years. According to the IPCC Special Report on Emission Scenarios (SRES), by the end of the 21st century, we could expect to see carbon dioxide concentrations of anywhere from 490 to 1260 ppm (75-350% above the pre-industrial concentration). -------------------------------------------------------------------------------- Is the climate warming? Yes. Global surface temperatures have increased about 0.6°C (plus or minus 0.2°C) since the late-19th century, and about 0.4°F (0.2 to 0.3°C) over the past 25 years (the period with the most credible data). The warming has not been globally uniform. Some areas (including parts of the southeastern U.S.) have, in fact, cooled over the last century. The recent warmth has been greatest over North America and Eurasia between 40 and 70°N. Warming, assisted by the record El Niño of 1997-1998, has continued right up to the present, with 2001 being the second warmest year on record after 1998. Linear trends can vary greatly depending on the period over which they are computed. Temperature trends in the lower troposphere (between about 2,500 and 26,000 ft.) from 1979 to the present, the period for which Satellite Microwave Sounding Unit data exist, are small and may be unrepresentative of longer term trends and trends closer to the surface. Furthermore, there are small unresolved differences between radiosonde and satellite observations of tropospheric temperatures, though both data sources show slight warming trends. If one calculates trends beginning with the commencement of radiosonde data in the 1950s, there is a slight greater warming in the record due to increases in the 1970s. There are statistical and physical reasons (e.g., short record lengths, the transient differential effects of volcanic activity and El Niño, and boundary layer effects) for expecting differences between recent trends in surface and lower tropospheric temperatures, but the exact causes for the differences are still under investigation (see National Research Council report "Reconciling Observations of Global Temperature Change"). An enhanced greenhouse effect is expected to cause cooling in higher parts of the atmosphere because the increased "blanketing" effect in the lower atmosphere holds in more heat, allowing less to reach the upper atmosphere. Cooling of the lower stratosphere (about 49,000-79,500ft.) since 1979 is shown by both satellite Microwave Sounding Unit and radiosonde data, but is larger in the radiosonde data. Relatively cool surface and tropospheric temperatures, and a relatively warmer lower stratosphere, were observed in 1992 and 1993, following the 1991 eruption of Mt. Pinatubo. The warming reappeared in 1994. A dramatic global warming, at least partly associated with the record El Niño, took place in 1998. This warming episode is reflected from the surface to the top of the troposphere. There has been a general, but not global, tendency toward reduced diurnal temperature range (DTR), (the difference between high and low daily temperatures) over about 50% of the global land mass since the middle of the 20th century. Cloud cover has increased in many of the areas with reduced diurnal temperature range. The overall positive trend for maximum daily temperature over the period of study (1950-93) is 0.1°C/decade, whereas the trend for daily minimum temperatures is 0.2°C/decade. This results in a negative trend in the DTR of -0.1°C/decade. Indirect indicators of warming such as borehole temperatures, snow cover, and glacier recession data, are in substantial agreement with the more direct indicators of recent warmth. Evidence such as changes in glacier length is useful since it not only provides qualitative support for existing meteorological data, but glaciers often exist in places too remote to support meteorological stations, the records of glacial advance and retreat often extend back further than weather station records, and glaciers are usually at much higher alititudes that weather stations allowing us more insight into temperature changes higher in the atmosphere. Large-scale measurements of sea-ice have only been possible since the satellite era, but through looking at a number of different satellite estimates, it has been determined that Arctic sea ice has decreased between 1973 and 1996 at a rate of -2.8 +/- 0.3%/decade. Although this seems to correspond to a general increase in temperature over the same period, there are lots of quasi-cyclic atmospheric dynamics (for example the Arctic Oscillation) which may also influence the extent and thickness of sea-ice in the Arctic. Sea-ice in the Antarctic has shown very little trend over the same period, or even a slight increase since 1979. Though extending the Antarctic sea-ice record back in time is more difficult due to the lack of direct observations in this part of the world. -------------------------------------------------------------------------------- Are El Niños related to Global Warming? El Niños are not caused by global warming. Clear evidence exists from a variety of sources (including archaeological studies) that El Niños have been present for hundreds, and some indicators suggest maybe millions, of years. However, it has been hypothesized that warmer global sea surface temperatures can enhance the El Niño phenomenon, and it is also true that El Niños have been more frequent and intense in recent decades. Recent climate model results that simulate the 21st century with increased greenhouse gases suggest that El Niño-like sea surface temperature patterns in the tropical Pacific are likely to be more persistent. -------------------------------------------------------------------------------- Is the hydrological cycle (evaporation and precipitation) changing? Overall, land precipitation for the globe has increased by ~2% since 1900, however, precipitation changes have been spatially variable over the last century. Instrumental records show that there has been a general increase in precipitation of about 0.5-1.0%/decade over land in northern mid-high latitudes, except in parts of eastern Russia. However, a decrease of about -0.3%/decade in precipitation has occurred during the 20th century over land in sub-tropical latitudes, though this trend has weakened in recent decades. Due to the difficulty in measuring precipitation, it has been important to constrain these observations by analyzing other related variables. The measured changes in precipitation are consistent with observed changes in streamflow, lake levels, and soil moisture (where data are available and have been analyzed). Northern Hemisphere annual snow cover extent has consistently remained below average since 1987, and has decreased by about 10% since 1966. This is mostly due to a decrease in spring and summer snowfall over both the Eurasian and North American continents since the mid-1980s. However, winter and autumn snow cover extent has shown no significant trend for the northern hemisphere over the same period. Improved satellite data shows that a general trend of increasing cloud amount over both land and ocean since the early 1980s, seems to have reversed in the early 1990s, and total cloud amount of land and ocean now appears to be decreasing. However, there are several studies that suggest regional cloudiness, perhaps especially in the thick precipitating clouds has increased over the 20th century. -------------------------------------------------------------------------------- Is the atmospheric/oceanic circulation changing? A rather abrupt change in the El Niño - Southern Oscillation behavior occurred around 1976/77 and the new regime has persisted. There have been relatively more frequent and presistent El Niño episodes rather than the cool La Niñas. This behavior is highly unusual in the last 120 years (the period of instrumental record). Changes in precipitation over the tropical Pacific are related to this change in the El Niño - Southern Oscillation, which has also affected the pattern and magnitude of surface temperatures. However, it is unclear as to whether this apparent change in the ENSO cycle is caused by global warming. -------------------------------------------------------------------------------- Is the climate becoming more variable or extreme? On a global scale there is little evidence of sustained trends in climate variability or extremes. This perhaps reflects inadequate data and a dearth of analyses. However, on regional scales, there is clear evidence of changes in variability or extremes. In areas where a drought or excessive wetness usually accompanies an El Niño, these dry or wet spells have been more intense in recent years. Other than these areas, little evidence is available of changes in drought frequency or intensity. In some areas where overall precipitation has increased (ie. the mid-high northern latitudes), there is evidence of increases in the heavy and extreme precipitation events. Even in areas such as eastern Asia, it has been found that extreme precipitation events have increased despite total precipitation remaining constant or even decreasing somewhat. This is related to a decrease in the frequency of precipitation in this region. Many individual studies of various regions show that extra-tropical cyclone activity seems to have generally increased over the last half of the 20th century in the northern hemisphere, but decreased in the southern hemisphere. It is not clear whether these trends are multi-decadal fluctuations or part of a longer-term trend. Where reliable data are available, tropical storm frequency and intensity show no significant long-term trend in any basin. There are apparent decadal-interdecadal fluctuations, but nothing which is conlusive in suggesting a longer-term component. Global temperature extremes have been found to exhibit no significant trend in interannual variability, but several studies suggest a significant decrease in intra-annual variability. There has been a clear trend to fewer extremely low minimum temperatures in several widely-separated areas in recent decades. Widespread significant changes in extreme high temperature events have not been observed. There is some indication of a decrease in day-to-day temperature variability in recent decades. -------------------------------------------------------------------------------- How important are these changes in a longer-term context? Paleoclimatic data are critical for enabling us to extend our knowledge of climatic variability beyond what is measured by modern instruments. Many natural phenomena are climate dependent (such as the growth rate of a tree for example), and as such, provide natural 'archives' of climate information. Some useful paleoclimate data can be found in sources as diverse as tree rings, ice cores, corals, lake sediments (including fossil insects and pollen data), speleothems (stalactites etc), and ocean sediments. Some of these, including ice cores and tree rings provide us also with a chronology due the nature of how they are formed, and so high resolution climate reconstruction is possible in these cases. However, there is not a comprehensive 'network' of paleoclimate data as there is with instrumental coverage, so global climate reconstructions are often difficult to obtain. Nevertheless, combining different types of paleoclimate records enables us to gain a near-global picture of climate changes in the past. For the Northern Hemisphere summer temperature, recent decades appear to be the warmest since at least about 1000AD, and the warming since the late 19th century is unprecedented over the last 1000 years. Older data are insufficient to provide reliable hemispheric temperature estimates. Ice core data suggest that the 20th century has been warm in many parts of the globe, but also that the significance of the warming varies geographically, when viewed in the context of climate variations of the last millennium. Large and rapid climatic changes affecting the atmospheric and oceanic circulation and temperature, and the hydrological cycle, occurred during the last ice age and during the transition towards the present Holocene period (which began about 10,000 years ago). Based on the incomplete evidence available, the projected change of 3 to 7°F (1.5 - 4°C) over the next century would be unprecedented in comparison with the best available records from the last several thousand years. -------------------------------------------------------------------------------- Is sea level rising? Global mean sea level has been rising at an average rate of 1 to 2 mm/year over the past 100 years, which is significantly larger than the rate averaged over the last several thousand years. Projected increase from 1990-2100 is anywhere from 0.09-0.88 meters, depending on which greenhouse gas scenario is used and many physical uncertainties in contributions to sea-level rise from a variety of frozen and unfrozen water sources. -------------------------------------------------------------------------------- Can the observed changes be explained by natural variability, including changes in solar output? Since our entire climate system is fundamentally driven by energy from the sun, it stands to reason that if the sun's energy output were to change, then so would the climate. Since the advent of space-borne measurements in the late 1970s, solar output has indeed been shown to vary. There appears to be confirmation of earlier suggestions of an 11 (and 22) year cycle of irradiance. With only 20 years of reliable measurements however, it is difficult to deduce a trend. But, from the short record we have so far, the trend in solar irradiance is estimated at ~0.09 W/m2 compared to 0.4 W/m2 from well-mixed greenhouse gases. There are many indications that the sun also has a longer-term variation which has potentially contributed to the century-scale forcing to a greater degree. There is though, a great deal of uncertainty in estimates of solar irradiance beyond what can be measured by satellites, and still the contribution of direct solar irradiance forcing is small compared to the greenhouse gas component. However, our understanding of the indirect effects of changes in solar output and feedbacks in the climate system is minimal. There is much need to refine our understanding of key natural forcing mechanisms of the climate, including solar irradiance changes, in order to reduce uncertainty in our projections of future climate change. In addition to changes in energy from the sun itself, the Earth's position and orientation relative to the sun (our orbit) also varies slightly, thereby bringing us closer and further away from the sun in predictable cycles (called Milankovitch cycles). Variations in these cycles are believed to be the cause of Earth's ice-ages (glacials). Particularly important for the development of glacials is the radiation receipt at high northern latitudes. Diminishing radiation at these latitudes during the summer months would have enabled winter snow and ice cover to persist throughout the year, eventually leading to a permanent snow- or icepack. While Milankovitch cycles have tremendous value as a theory to explain ice-ages and long-term changes in the climate, they are unlikely to have very much impact on the decade-century timescale. Over several centuries, it may be possible to observe the effect of these orbital parameters, however for the prediction of climate change in the 21st century, these changes will be far less important than radiative forcing from greenhouse gases. -------------------------------------------------------------------------------- What about the future? Due to the enormous complexity of the atmosphere, the most useful tools for gauging future changes are 'climate models'. These are computer-based mathematical models which simulate, in three dimensions, the climate's behavior, its components and their interactions. Climate models are constantly improving based on both our understanding and the increase in computer power, though by definition, a computer model is a simplification and simulation of reality, meaning that it is an approximation of the climate system. The first step in any modeled projection of climate change is to first simulate the present climate and compare it to observations. If the model is considered to do a good job at representing modern climate, then certain parameters can be changed, such as the concentration of greenhouse gases, which helps us understand how the climate would change in response. Projections of future climate change therefore depend on how well the computer climate model simulates the climate and on our understanding of how forcing functions will change in the future. The IPCC Special Report on Emission Scenarios determines the range of future possible greenhouse gas concentrations (and other forcings) based on considerations such as population growth, economic growth, energy efficiency and a host of other factors. This leads a wide range of possible forcing scenarios, and consequently a wide range of possible future climates. According to the range of possible forcing scenarios, and taking into account uncertainty in climate model performance, the IPCC projects a global temperature increase of anywhere from 1.4 - 5.8°C from 1990-2100. However, this global average will integrate widely varying regional responses, such as the likelihood that land areas will warm much faster than ocean temperatures, particularly those land areas in northern high latitudes (and mostly in the cold season). Precipitation is also expected to increase over the 21st century, particularly at northern mid-high latitudes, though the trends may be more variable in the tropics. Snow extent and sea-ice are also projected to decrease further in the northern hemisphere, and glaciers and ice-caps are expected to continue to retreat. -------------------------------------------------------------------------------- Additional Information/links Intergovernmental Panel on Climate Change U.S. Environmental Protection Agency World Data Center for Greenhouse Gases A Paleoclimate perspective on global warming EL Niño/La Niña Climate of 2003 Climate of 2002 Climate of 2001, comprehensive (large pdf file)/ brief (html) Climate of 2000, comprehensive (large pdf file)/ brief (html) Climate of 1999 Climate of 1998 U.S. Climate Returns to Heat of the 1930s as Global Warmth Continues http://lwf.ncdc.noaa.gov/oa/climate/globalwarming.html Downloaded Sunday, 09-Mar-2008 08:18:09 EDT Last Updated Thursday, 29-Mar-2007 13:20:18 EDT by Anne.Waple@noaa.gov Link to comment Share on other sites More sharing options...
Guest Guest Posted March 9, 2008 Report Share Posted March 9, 2008 You are all being hoodwinked by this shuckster. Glad that al gore ain't president. Read this: http://globalwarminghoax.wordpress.com/ Link to comment Share on other sites More sharing options...
Guest Tom's Mom Posted March 9, 2008 Report Share Posted March 9, 2008 You are all being hoodwinked by this shuckster. Glad that al gore ain't president. Read this: http://globalwarminghoax.wordpress.com/ Well, THAT was a waste of time! Thanks a lot! Where do you find such crap? Newsmax?? Link to comment Share on other sites More sharing options...
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