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Авторский перевод статей о климате и его изменениях
Выполнила: Ключенко Александра Григорьевна
An Overview of Climate
Climate, Climate Classification, and Climate Change
Climate is defined as the average weather patterns existing throughout several years over a large portion of Earth's surface. Usually, climate is measured for a specific area or region based on weather patterns over a 30-35 year time period. Climate therefore varies from weather because weather is concerned only with short term events. A simple way to remember the distinction between the two is the saying, "Climate is what you expect, but weather is what you get."
Since climate is composed of long-term average weather patterns, it encompasses the average measurements of various meteorological elements like humidity, atmospheric pressure, wind, precipitation and temperature. In addition to these components, Earth's climate is also composed of a system consisting of its atmosphere, oceans, land masses and topography, ice and biosphere. Each of these is a part of the climate system for their ability to influence long-range weather patterns. Ice for example, is significant to climate because it has a high albedo, or is highly reflective, and covers 3% of the Earth's surface, therefore helping to reflect heat back into space.
Although an area's climate is normally a result of a 30-35 year average, scientists have been able to study past climate patterns for a large part of Earth's history through paleoclimatology. In order to study past climates, paleoclimatologists use evidence from ice sheets, tree rings, sediment samples, coral and rocks to determine how much Earth's climate has changed through time. With these studies, scientists have found that Earth has experienced various periods of stable climate patterns as well as periods of climate change.
Today, scientists determine the modern climate record through measurements taken via thermometers, barometers (an instrument measuring atmospheric pressure) and anemometers (an instrument measuring wind speed) over the past few centuries.
Many scientists or climatologists studying Earth's past and modern climate record do so in an attempt to establish useful climate classification schemes. In the past for example, climates were determined based on travel, regional knowledge and latitude. An early attempt the classify Earth's climates was Aristotle's Temperate, Torrid and Frigid Zones. Today, climate classifications are based on the causes and effects of climate. A cause for example would be the relative frequency over time of a specific type of air mass over an area and the weather patterns it causes. A climate classification based on an effect would be one concerned with vegetation types present an area.
The Köppen System
The most widely used climate classification system in use today is the Köppen System, which was developed over a period from 1918 to 1936 by Vladimir Köppen. The Köppen System (map) classifies the Earth's climates based on natural vegetation types as well as the combination of temperature and precipitation.
In order to classify different regions based on these factors, Köppen used a multi-tiered classification system with letters ranging from A-E (chart). These categories are based on temperature and precipitation but generally line up based on latitude. For example, a climate with a type A, is tropical and because of its characteristics, a climate type A is almost completely confined to the region between the equator and the Tropics of Cancer and Capricorn. The highest climate type in this scheme is polar and in these climates, all months have a temperature below 50°F (10°C).
In the Köppen System, the A-E climates are then subdivided into smaller zones which are represented by a second letter, which can then be further subdivided to show more detail. For A climates for example, the second letters of f, m and w indicate when or if a dry season occurs. Af climates have no dry season (such as in Singapore) while Am climates are monsoonal with a short dry season (as in Miami, Florida) and Aw has a distinctive long dry season (such as that of Mumbai).
The third letter in the Köppen classifications represents the temperature pattern of the area. For example, a climate classified as Cfb in the Köppen System would be mild, located on the marine west coast, and would experience mild weather throughout the year with no dry season and a warm summer. A city with a climate of Cfb is Melbourne, Australia.
Thornthwaite's Climate System
Although Köppen's System is the most widely used climate classification system, there are several others that have been used as well. One of the more popular of these is the climatologist and geographer C.W. Thornthwaite's system. This method monitors the soil water budget for an area based on evapotranspiration and considers that along with total precipitation used to support an area's vegetation over time. It also uses a humidity and aridity index to study an area's moisture based on temperature, rainfall and vegetation type. The moisture classifications in Thornthwaite's system are based on this index and the lower the index is, the drier an area is. Classifications range from hyperhumid to arid.
Temperature is also considered in this system with descriptors ranging from microthermal (areas with low temperatures) to megathermal (areas with high temperatures and high rainfall).
A major topic in climatology today is that of climate change which refers to the variation of Earth's global climate over time. Scientists have discovered that Earth has undergone several climate changes in the past which include various shifts from glacial periods or ice ages to warm, interglacial periods.
Today, climate change is mainly to describe the changes occurring in modern climate such as an increase in sea surface temperatures and global warming
Various attempts have been made to classify the climates of the earth into climatic regions. One notable, yet ancient and misguided example is that of Aristotle's Temperate, Torrid, and Frigid Zones. However, the 20th century classification developed by German climatologist and amateur botanist Wladimir Koppen (1846-1940) continues to be the authoritative map of the world climates in use today.
Introduced in 1928 as a wall map co-authored with student Rudolph Geiger, the Koppen system of classification (overview map) was updated and modified by Koppen until his death. Since that time, it has been modified by several geographers. The most common modification of the Köppen system today is that of the late University of Wisconsin geographer Glen Trewartha.
The modified Koppen classification uses six letters to divide the world into six major climate regions, based on average annual precipitation, average monthly precipitation, and average monthly temperature. . . (click the links for a map of each classification)
* A for Tropical Humid
* B for Dry
* C for Mild Mid-Latitude
* D for Severe Mid-Latitude
* E for Polar
* H for Highland (this classification was added after Köppen created his system)
Each category is further divided into sub-categories based on temperature and precipitation. For instance, the U.S. states located along the Gulf of Mexico are designated as "Cfa." The "C" represents the "mild mid-latitude" category, the second letter "f" stands for the German word feucht or "moist," and the third letter "a" indicates that the average temperature of the warmest month is above 72°F (22°C). Thus, "Cfa" gives us a good indication of the climate of this region, a mild mid-latitude climate with no dry season and a hot summer.
While the Koppen system doesn't take such things as temperature extremes, average cloud cover, number of days with sunshine, or wind into account, it's a good representation of our earth's climate. With only 24 different subclassifications, grouped into the six categories, the system is easy to comprehend.
Koppen's system is simply a guide to the general climate of the regions of the planet, the borders do not represent instantaneous shifts in climate but are merely transition zones where climate, and especially weather, can fluctuate.
Jun 26 2008
Global Warming, the general increase in the earth's near-surface air and ocean temperatures, remains a pressing issue in a society that has expanded its industrial use since the mid-twentieth century.
Greenhouse gases, atmospheric gases that exist to keep our planet warm and prevent warmer air from leaving our planet, are enhanced by industrial processes. As human activity such as the burning of fossil fuels and deforestation increases, greenhouse gases such as Carbon Dioxide are released into the air. Normally, when heat enters the atmosphere, it is through short-wave radiation; a type of radiation that passes smoothly through our atmosphere. As this radiation heats the earth's surface, it escapes the earth in the form of long-wave radiation; a type of radiation that is much more difficult to pass through the atmosphere. Greenhouse gases released into the atmosphere cause this long-wave radiation to increase. Thus, heat is trapped inside of our planet and creates a general warming effect.
Scientific organizations around the world, including The Intergovernmental Panel on Climate Change, the InterAcademy Council, and over thirty others, have projected a significant change and future increase in these atmospheric temperatures. But what are the real causes and effects of global warming? What does this scientific evidence conclude in regards to our future?
Causes of Global Warming
The crucial component that causes greenhouse gases such as CO2, Methane, Chlorofluorocarbons (CFC's), and Nitrous Oxide to be released into the atmosphere is human activity. The burning of fossil fuels (i.e., non-renewable resources such as oil, coal, and natural gas) has a significant effect on the warming of the atmosphere. The heavy use of power plants, cars, airplanes, buildings, and other man-made structures release CO2 into the atmosphere and contribute to global warming.
Nylon and nitric acid production, the use of fertilizers in agriculture, and the burning of organic matter also release the greenhouse gas Nitrous Oxide. These are processes that have been expanded since the mid-twentieth century.
Another cause of global warming is land-use changes such as deforestation. When forest land is destroyed, carbon dioxide is released into the air thus increasing the long-wave radiation and trapped heat. As we lose millions of acres of rainforest a year, we are also losing wildlife habitats, our natural environment, and most significantly, a non-regulated air and ocean temperature.
Effects of Global Warming
The increase in the warming of the atmosphere has significant effects on both natural environment and human life. Obvious effects include glacial retreat, Arctic shrinkage, and worldwide sea level rise. There are also less obvious effects such as economic trouble, ocean acidification, and population risks. As climate changes, everything changes from the natural habitats of wildlife to the culture and sustainability of a region.
Melting of the Polar Ice Caps
One of the most obvious effects of global warming involves the melting of the polar ice caps. According to the National Snow and Ice Data Center, there are 5,773,000 cubic miles of water, ice caps, glaciers, and permanent snow on our planet. As these continue to melt, sea levels rise. Rising sea levels are also caused by expanding ocean water, melting mountain glaciers, and the ice sheets of Greenland and Antarctica melting or sliding into the oceans. Rising sea levels result in coastal erosion, coastal flooding, increased salinity of rivers, bays, and aquifers, and shoreline retreat.
Melting ice caps will desalinize the ocean and disrupt natural ocean currents. Since ocean currents regulate temperatures by bringing warmer currents into cooler regions and cooler currents into warmer regions, a halt in this activity may cause extreme climate changes, such as Western Europe experiencing a mini-ice age.
Another important effect of melting ice caps lies in a changing albedo. Albedo is the ratio of the light reflected by any part of the earth's surface or atmosphere. Since snow has one of the highest albedo level, it reflects sunlight back into space, helping to keep the earth cooler. As it melts, more sunlight is absorbed by the earth's atmosphere and the temperature tends to increase. This further contributes to global warming.
Another effect of global warming is changes in wildlife adaptations and cycles, an alteration of the natural balance of the earth. In Alaska alone, forests are continually destroyed due to a bug known as the spruce bark beetle. These beetles usually appear in the warmer months but since the temperatures have increased, they have been appearing year-round. These beetles chew on spruce trees at an alarming rate, and with their season being stretched for a longer period of time, they have left vast boreal forests dead and gray.
Another example of changing wildlife adaptations involves the polar bear. The polar bear is now listed as a threatened species under the Endangered Species Act. Global warming has significantly reduced its sea ice habitat; as the ice melts, polar bears are stranded and often drown. With the continuous melting of ice, there will be less habitat opportunities and a risk in extinction of the species.
As Carbon Dioxide emissions increase, the ocean becomes more acidic. This acidification affects everything from an organism's ability to absorb nutrients to changes in chemical equilibrium and therefore natural marine habitats.
Since coral is very sensitive to increased water temperature over a long period of time, they lose their symbiotic algae, a type of algae that gives them coral color and nutrients. Losing these algae results in a white or bleached appearance, and is eventually fatal to the coral reef. Since hundreds of thousands of species thrive on coral as a natural habitat and means of food, coral bleaching is also fatal to the living organisms of the sea.
Spread of Disease
Global warming will also enhance the spread of diseases. As northern countries warm, disease-carrying insects migrate north, carrying viruses with them that we have not yet built immunity for.
Floods and Droughts and Global Warming
Strong shifts in precipitation patterns will ensue as global warming progresses. Some areas of the earth will become wetter, while others will experience heavy droughts. Since warmer air brings heavier storms, there will be an increased chance of stronger and more life-threatening storms. According to the Intergovernmental Panel on Climate, Africa, where water is already a scarce commodity, will have less and less water with warmer temperatures and this issue could even lead to more conflict and war.
Global warming has caused heavy rains in the United States due to warmer air having the ability to hold more water vapor than cooler air. Floods that have impacted the United States since 1993 alone have caused over $25 billion in losses. With increased floods and droughts, not only will our safety be affected, but also the economy.
Since disaster relief takes a heavy toll on the world's economy and diseases are expensive to treat, we will suffer financially with the onset of global warming. After disasters such as Hurricane Katrina in New Orleans, one can only imagine the cost of more hurricanes, floods, and other disasters occurring worldwide.
Population Risk and Unsustainable Development
Projected sea-level rise will greatly affect low-lying coastal areas with large populations in developed and developing countries worldwide. According to National Geographic, the cost of adaptation to a newer climate could result in at least 5% to 10% of gross domestic product. As mangroves, coral reefs, and the general aesthetic appeal of these natural environments are further degraded, there will also be a loss in tourism.
Similarly, climate change impinges on sustainable development. In developing Asian countries, a cyclic disaster occurs between productivity and global warming. Natural resources are needed for heavy industrialization and urbanization. Yet, this industrialization creates immense amounts of greenhouse gases, thus depleting the natural resources needed for further development of the country. Without finding a new and more efficient way to use energy, we will be depleted of our natural resources needed for our planet to thrive.
Future Outlook of Global Warming: What can we do to help?
Studies performed by the British government show that to avert potential disaster in relation to global warming, greenhouse gas emissions must be reduced by approximately 80%. But how can we preserve this vast amount of energy that we are so accustomed to using?
In February 2002, the United States government announced a strategy to reduce greenhouse gas emissions by 18% over a 10-year period from 2002-2012. This policy involves reducing emissions through technology improvements and dissemination, improving the efficiency of energy use, and voluntary programs with industry and shifts to cleaner fuels.
Other U.S. and international policies, such as the Climate Change Science Program and the Climate Change Technology Program, have been reinstated with a comprehensive objective of reducing greenhouse gas emissions through international cooperation. As the governments of our world continue to understand and acknowledge the threat of global warming to our livelihood, we are closer to reducing greenhouse gases to a manageable size.
Plants absorb the greenhouse gas Carbon Dioxide (CO2) from the atmosphere for photosynthesis, the conversion of light energy into chemical energy by living organisms. Increased forest cover will help plants remove CO2 from the atmosphere and help alleviate global warming. Although having a small impact, this would help reduce one of the most significant greenhouse gases contributing to global warming.
There are small actions that we can all take in order to help reduce greenhouse gas emissions. First, we can reduce electricity use around the house. The average home contributes more to global warming than the average car. If we switch to energy-efficient lighting, or reduce energy needed for heating or cooling, we will make a change in emissions.
This reduction can also be made through improving vehicle-fuel efficiency. Driving less than needed or buying a fuel-efficient car will reduce greenhouse gas emissions. Although it's a small change, many small changes will someday lead to a bigger change.
Global Warming and The Road Ahead
As global warming progresses, natural resources will be further depleted, and there will be risks of wildlife extinctions, melting of the polar ice caps, coral bleaching and disintegration, floods and droughts, disease, economic disaster, sea level rise, population risks, unsustainable land, and more. As we live in a world characterized by industrial progress and development aided by the help of our natural environment, we are also risking depletion of this natural environment and thus of our world as we know it. With a rational balance between protecting our environment and developing human technology, we will live in a world where we can simultaneously progress the capabilities of mankind with the beauty and necessity of our natural environment.
Apr 10 2008
Global warming, an increase in the earth's average atmospheric temperature that causes corresponding changes in climate, is a growing environmental issue caused by the influx of human industry and agriculture in the mid-twentieth-century to the present. As greenhouse gases such as CO2 and methane are released into the atmosphere, a shield forms around our Earth, trapping heat inside of our planet and therefore creating a general warming effect. One of the most influenced territories of warming has been our oceans.
Rising air temperatures affect the physical nature of our oceans. As air temperatures rise, water becomes less dense and separates from a nutrient-filled cold layer below.
There are two general physical effects of ocean warming on marine populations that are crucial to consider:
* Changes in natural habitats and food supply
* Changing ocean chemistry/acidification
Photosynthesis is a process that removes carbon dioxide from the atmosphere and converts it into organic carbon and oxygen that feeds almost every ecosystem. According to a recent NASA study, phytoplankton is more likely to thrive in cooler oceans. Similarly, algae, a plant that produces food for other marine life through photosynthesis, is vanishing due to ocean warming.
The warming of oceans may also lead to migration of organisms along the east and west coasts. Heat-tolerant species, such as shrimp, will expand northward, while heat-intolerant species, such as flounder, will retreat northward. This migration will lead to a new mix of organisms in an entirely new environment, ultimately causing changes in predatory habits. If some organisms cannot adapt to their new marine environment, they will not flourish and die off.
As carbon dioxide is being released into the ocean, the ocean chemistry drastically changes. Greater CO2 concentrations released into our oceans create increased ocean acidity. As ocean acidity increases, Phytoplankton is reduced. This results in less ocean plants able to uptake greenhouse gases. Also, increased ocean acidity threatens marine life, such as corals and shellfish.
Acidification Effect on Coral Reefs
Coral, one of the leading sources for the ocean's food and livelihood, is also changing with the onset of global warming. Naturally, coral secretes tiny shells of calcium carbonate in order to form its skeleton. Yet, as CO2 from global warming is released into the atmosphere, acidification increases and the carbonate ions vanish.
Coral bleaching, the breakdown in the symbiotic relationship between coral and algae, is also occurring with warmer ocean temperatures. Since Zooxanthellae, or algae, give coral its particular coloration, increased CO2 in our oceans causes coral stress and a release of this algae. This leads to a lighter appearance. When this relationship that is so important for our ecosystem to survive vanishes, corals begin to weaken. Consequently, food and habitats for a great number of marine life are also destroyed.
Holocene Climatic Optimum
This drastic climate change and its effect on surrounding wildlife is not news to us. The Holocene Climatic Optimum, a general warming period displayed in our fossil record from 9,000 to 5,000 B.P., proves that climate change can directly impact nature's inhabitants. In 10,500 B.P., younger dryas, a plant that was once spread throughout the world in various cold climates, became near extinct due to this warming period. Towards the end of the warming period, this plant that so much of nature had depended on was only to be found in the few areas that remained cold.
Future Outlook and Human Effects
The warming of our oceans and its effect on marine life has a direct impact on us. As coral reefs die, we will lose an entire ecological habitat of fish. According to the World Wildlife Fund, a small increase of two degrees Celsius would destroy almost all existing coral reefs. Additionally, ocean circulation changes due to warming would have disastrous impacts on marine fisheries.
This drastic impact is often hard to imagine. It can only be related to a similar historical event. Fifty-five million years ago, ocean acidification led to a mass extinction of ocean creatures. According to our fossil record, it took more than 100,000 years for the oceans to recover. Eliminating the use of greenhouse gases and protecting our oceans will prevent this from reoccurring.
On Friday, February 2, 2007, the United Nations’ Intergovernmental Panel on Climate Change (IPCC)—the leading international group of climate scientists—published a 20-page summary of a much longer scientific report, The Physical Basis of Climate Change, which confirms global warming is now “unequivocal” and states with more than 90 percent certainty that human activity “very likely” has been the primary cause of rising temperatures worldwide since 1950.
The report summary also says that global warming is likely to continue for centuries, and that it is already too late to stop some of the serious consequences it will bring—even if mankind could somehow hold the line on greenhouse gas emissions worldwide starting today.
Despite those grim conclusions, however, the report does say that there is still time to slow global warming and to lessen many of its most severe consequences if we act quickly.
This article answers some of the most common questions about the IPCC report and its predictions for the future of our planet.
Q: What are the expected consequences of global warming based on the summary of the fourth IPCC assessment of climate change science?
A: Global temperatures are expected to increase 3.5 to 8 degrees Fahrenheit by 2050, and there is a 1-in-10 chance that the increase could be far worse, a risk that many experts believe is too great to ignore.
Rising temperatures will alter global weather patterns that have a direct effect on water supplies and agriculture. Deserts will expand, the frequency and severity of droughts and deadly heat waves will increase, and snow will disappear in most areas—except on the very highest mountain peaks.
Sea levels worldwide are expected to rise between 7 and 23 inches by 2100, and will continue to rise for at least the next 1,000 years.
Fierce storms, such as hurricanes, will become more frequent and more floods will occur, due to rising sea levels and heavier rainfall in some areas.
Continuing global warming will also lead to a rise in many diseases that are deadly to humans. Flooding will contaminate water supplies in some areas, giving rise to infectious diseases. Rising temperatures will also increase the range and breeding grounds of mosquitoes and other disease-bearing insects, exposing more people to diseases such as malaria, yellow fever and encephalitis.
Q: What does the IPCC report say about the relationship between global warming and human activity?
A: In the strongest language ever used by the IPCC, the report says that human activity “very likely” has been the primary cause of global warming since 1950.
The report summary also says that human activity has been a major contributor to climate change since the Industrial Revolution, which began around 1750.
Global concentrations of carbon dioxide, methane and nitrous oxide—three of the most notable greenhouse gases—have increased significantly over the past 250 years as direct result of human activities. Concentrations of carbon dioxide and other greenhouse gases now far exceed any found during ice core research spanning the past 650,000 years.
The increase of carbon dioxide is due primarily to the use of fossil fuels, such as oil and coal, and changes in land use, such as cutting down forests to make way for farming, housing and other development. Increases in methane and nitrous oxide are primarily due to agriculture.
Q: What does the report say about the risks of rising sea levels due to global warming?
A: Sea levels worldwide are expected to rise between 7 and 23 inches by 2100, and will continue to rise for at least the next 1,000 years. By comparison, global sea levels rose 6 to 9 inches in the 20th century, so the effects of global warming on sea levels are clearly accelerating.
Rising sea levels will create millions of environmental refugees as people are forced to leave their homes in coastal areas.
Increased levels of carbon dioxide in the atmosphere will change the pH balance of seawater, making it slightly more acidic. Although the oceans will remain alkaline, marine biologists predict that a shift toward greater acidity could threaten the survival of coral reefs and plankton—an essential and fundamental link in the marine food chain.
Even a moderate increase in the build up of greenhouse gases in the atmosphere could easily push average global temperatures to levels last seen 125,000 years ago during a warm period between two ice ages. At that time, sea levels were 12 to 20 feet higher than they are today. Much of the water from that earlier period is now frozen in Greenland and Antarctica, but many of those ice fields are beginning to melt.
Because scientists are not certain how quickly polar ice will melt, the estimates of sea level increases in the report are based on how much warming oceans will expand and do not take into account anticipated runoff from melting ice on land in Greenland and the polar regions.
Official agencies from the U.S. to the U.K. have declared 2007 the second warmest year on record—and the hottest ever in the Northern Hemisphere—despite a variety of climate conditions that usually lead to cooler temperatures. Was 2007 Really the Second Warmest Year on Record?
“With the record for 2007 now complete, it is clear that temperatures around the world are continuing their upward climb,” according to a statement from the Earth Policy Institute. “The global average in 2007 was 14.73 degrees Celsius (58.5 degrees Fahrenheit)—the second warmest year on record, only 0.03 degrees Celsius behind the 2005 maximum. January 2007 was the hottest January ever measured, a full 0.23 degrees Celsius warmer than the previous record.”
2007 Hottest Year for Northern Hemisphere
Looking at the northern hemisphere alone, 2007 temperatures averaged 15.04 degrees Celsius (59.1 degrees Fahrenheit)—easily the hottest year in the northern half of the globe since the record began in 1880, and more than a degree warmer than the 1951–1980 average. Paleo-temperature records from ancient tree rings suggest that the northern hemisphere is now warmer than at any time in at least the last 1,200 years.
2007 fits into a pattern of steadily increasing global average temperature, with the eight warmest years on record all occurring in the last decade. According to data maintained by NASA’s Goddard Institute for Space Studies, global average temperature rose from 14.02 degrees Celsius in the 1970s to 14.26 degrees in the 1980s and then to 14.40 degrees in the 1990s. In the first eight years of the 21st century, the world averaged 14.64 degrees Celsius. Since 1990, mean global temperature has risen by 0.33 degrees, a rate of increase faster than climate models had predicted.
2007 Second Warmest Year Despite Cooling Climate Conditions
Although 2007 did not post a new record high, the year stands out as being extremely warm despite several natural factors that usually cool the planet. El Niño conditions in the southern Pacific tend to increase the global average temperature, and yet the second half of 2007 saw the opposite—a La Niña pattern that would usually depress global temperature.
This is in stark contrast to conditions in 1998, now the third warmest year on record, when temperatures were boosted around 0.2 degrees Celsius by the strongest El Niño of the century. In addition to the moderate La Niña in 2007, solar intensity in 2007 was slightly lower than average because the year was a minimum in the 11-year solar sunspot cycle. The combination of these factors would normally produce cooler temperatures, yet 2007 was still one of the warmest years in human history. According to the Earth Policy Institute, this strongly suggests that the warming effect of increased greenhouse gas concentrations is now dwarfing other influences on the Earth’s climate.
Warm 2007 Marked by Extreme Weather
While some areas baked under intensive heat or drought conditions, others were inundated by record amounts of rain. England and Wales experienced widespread flooding and damage estimated at £3 billion ($6 billion) during the wettest May to July period since records began in 1766. In South Asia, some of the worst flooding in decades occurred during the monsoon season, affecting at least 25 million people and killing more than 2,500.
Fifteen countries across Africa—from Ghana to Ethiopia—were affected by severe floods in the summer of 2007. The flooding displaced hundreds of thousands of people and washed away crops and farmland, seriously damaging food security in the region.
Intense rainfall events and flooding will become more common in the future. This means more heavy rainstorms but also more dry periods, producing more severe droughts as well as more frequent and intense floods. Rainfall data from the 20th century show precipitation intensity increasing over the last two decades, suggesting this trend is already beginning.
UN Science Panel Confirms Effects of Humans on Global Climate
In 2007, the Intergovernmental Panel on Climate Change released its Fourth Assessment Report, which detailed the likely climatic consequences if human beings continue to pump greenhouse gases into the atmosphere. It reported that unabated emissions would result in a temperature rise of between 1.1 and 6.4 degrees Celsius (2 to 12 degrees Fahrenheit) during the 21st century.
To put this in perspective, temperatures over the last 100 years rose by a comparably small 0.74 degrees Celsius, and yet this appears to have already contributed to trends of more heat waves, longer and more intense droughts, higher sea level, more frequent heavy rain, and stronger hurricanes.
“The many effects of warmer temperature, which we are already beginning to see, will only become more severe and more costly to society if greenhouse gas emissions are not cut quickly and dramatically," according to the Earth Policy Institute. “Our future now depends on what we do to limit warming by moving away from climate-disrupting fossil fuels and toward renewable energy and energy-efficient technologies”
Scholars Predict 50 Million “Environmental Refugees” by 2010
Scholars are predicting that 50 million people worldwide will be displaced by 2010 because of rising sea levels, desertification, weather-induced flooding and other serious environmental changes. So says Andrew Simms, policy director of the New Economics Foundation in the United Kingdom and the author of a book titled, “Environmental Refugees: The Case for Recognition.”
In an interview with Steve Curwood, host of Living on Earth, an independent media program funded by listener contributions and institutions that support public service, Simms says that these people should be considered “environmental refugees” and given refugee status under international law.
No Aid Available to “Environmental Refugees”
According to the United Nations University (UNU), an international community scholars that work on pressing global problems, victims of political upheaval or violence have access through governments and international organizations to assistance such as financial grants, food, tools, shelter, schools and clinics, but “environmental refugees” receive no such aid because they are not yet recognized in world conventions.
The UNU says that environmental problems already have contributed to large permanent migrations and could eventually displace hundreds of millions of people. Meanwhile, Red Cross research shows more people are now displaced by environmental disasters than by war.
Simms argues that because the homes of these displaced people are being gradually destroyed as a result of environmental policies pursued by industrialized nations, it amounts to “environmental persecution,” which makes them legitimate refugees deserving of legal protection.
Scholars at the United Nations University agree.
“There are well-founded fears that the number of people fleeing untenable environmental conditions may grow exponentially as the world experiences the effects of climate change and other phenomena,” says Janos Bogardi, director of UNU’s Institute for Environment and Human Security (UNU-EHS). “This new category of ‘refugee’ needs to find a place in international agreements. We need to better anticipate support requirements, similar to those of people fleeing other unviable situations.”
Environmental Changes Causing Widespread Migration
Environment-related migration has been most acute in Sub-Saharan Africa, but also affects millions of people in Asia and India. Meanwhile, Europe and the United States are witnessing increasing pressure from victims of often mismanaged and deteriorating soil and water conditions in North Africa and Latin America.
Such migrations may grow dramatically in future:
* Among many global problem sites, Yemen’s capital, has doubled its population on average every six years since 1972 and now stands at 900,000. The aquifer on which the city depends is falling by 6 meters a year, and may be exhausted by 2010, according to the World Bank.
* In China, the Gobi desert expands more than 10,000 square kilometers per year, threatening many villages. Oxford-based expert Norman Myers says Morocco, Tunisia and Libya each lose over 1,000 square kilometers of productive land annually to desertification.
* In Egypt, half of irrigated croplands suffer from salinization, while in Turkey 160,000 square kilometers of farmlands is affected by soil erosion.
* In the United States, Louisiana now loses roughly 65 square kilometers per year to erosion by the sea, while in Alaska 213 communities are threatened by tides that creep roughly 3 meters further inland each year.
* The low-lying Pacific island state of Tuvalu has struck an agreement with New Zealand to accept its 11,600 citizens in the event rising sea levels swamp the country.
* By one rough estimate, as many as 100 million people worldwide live in areas below sea level and/or are subject to storm surge.
“Around the world, vulnerability is on the increase due to the rapid development of megacities in coastal areas,” says Dr. Tony Oliver-Smith, a Florida professor.
“Combine this trend with rising sea levels and the growing number and intensity of storms and it is the recipe for a disaster-in-waiting, with enormous potential to create waves of environment-driven migration.”
Climatologists have been raising alarms about global warming for years, and now geologists are getting into the act, warning that melting glaciers will lead to an increasing number of earthquakes, tsunamis and volcanic eruptions in unexpected places.
People in northern climates who have been looking south and shaking their heads sadly over the plight of people living in the path of Atlantic hurricanes and Pacific tsunamis had better get ready for a few seismic events of their own, according to a growing number of prominent geologists.
Less Glacial Pressure, More Earthquakes and Volcanic Eruptions
Ice is extremely heavy—weighing about one ton per cubic meter—and glaciers are massive sheets of ice. When they are intact, glaciers exert enormous pressure on the portion of the Earth’s surface they cover. When glaciers begin to melt—as they are doing now at an increasingly rapid rate due to global warming—that pressure is reduced and eventually released.
Geologists say releasing that pressure on the Earth’s surface will cause all sorts of geologic reactions, such as earthquakes, tsunamis (caused by undersea earthquakes) and volcanic eruptions.
"What happens is the weight of this thick ice puts a lot of stress on the earth," said Patrick Wu, a geologist at the University of Alberta in Canada, in an interview with the Canadian Press. "The weight sort of suppresses the earthquakes, but when you melt the ice the earthquakes get triggered."
Global Warming Accelerating Geologic Rebound
Wu offered the analogy of pressing a thumb against a soccer ball. When the thumb is removed and the pressure released, the ball resumes its original shape. When the “ball” is a planet, the rebound happens slowly, but just as surely.
Wu said many of the earthquakes that occur in Canada today are related to the ongoing rebound effect that started with the end of the last ice age 10,000 years ago. But with global warming accelerating climate changes and causing glaciers to melt more quickly, Wu said the inevitable rebound is expected to happen much faster this time around.
New Seismic Events Already Happening
Wu said melting ice in Antarctica is already triggering earthquakes and underwater landslides. These events aren’t getting much attention, but they are early warnings of the more serious events that scientists believe are coming. According to Wu, global warming will create “lots of earthquakes.”
Professor Wu is not alone in his assessment.
Writing in New Scientist magazine, Bill McGuire, professor of geological hazards at University College in London, said: "All over the world evidence is stacking up that changes in global climate can and do affect the frequencies of earthquakes, volcanic eruptions and catastrophic sea-floor landslides. Not only has this happened several times throughout Earth's history, the evidence suggests it is happening again."
Источник статей: Журнал «Scientific American». Путь доступа: http://www.scientificamerican.com/
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