Global Warming

Natural phenomena such as solar variation combined with volcanoes have probably had a small warming effect from pre-industrial times to 1 950, but a cooling effect since 1950. The basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all Of the national academies Of science Of the major industrialized countries. The American Association of Petroleum Geologists is the only scientific society that rejects these conclusions,[2][3] and a few individual scientists also disagree with parts of them. 4] Climate models referenced by he EPIC project that global surface temperatures are likely to increase by 1. 1 to 6. 4 co (2. 0 to 11. 5 OF) between 1990 and 2100. 11] The range values reflects the use of differing scenarios of future greenhouse gas emissions and results of models with differences in climate sensitivity. Although most studies focus on the period up to 21 00, warming and sea level rise are expected to continue for more than a millennium even if greenhouse gas levels are stabilized. [l ] This reflects the large heat capacity of the oceans.

An increase in global temperatures can in turn cause other changes, including EAI level rise, and changes in the amount and pattern of precipitation. There may also be changes in the frequency and intensity of extreme weather events, though it is difficult to connect specific events to global warming. Other effects may include changes in agricultural yields, glacier retreat, reduced summer streetlamps, species extinctions and increases in the ranges of disease vectors. Remaining scientific uncertainties include the exact degree of climate change expected in the future, and how changes will vary from region to region around the globe.

There is ongoing political and public abate regarding what, if any, action should be taken to reduce or reverse future warming or to adapt to its expected consequences. Most national governments have signed and ratified the Kyoto Protocol aimed at combating greenhouse gas emissions. Causes Causes [pick] [pick Carbon dioxide during the last 400,000 years and the rapid rise since the Industrial Revolution; changes in the Earth’s orbit around the Sun, known as Implantation cycles, are believed to be the pacemaker of the 100,000 year ice age cycle.

Main articles: Attribution of recent climate change and scientific pinion on climate change The climate system varies through natural, internal processes and in response to variations in external forcing factors including solar activity, volcanic emissions, variations in the earth’s orbit (orbital forcing) and greenhouse gases. The detailed causes of the recent warming remain an active field of research, but the scientific consensus[7] identifies increased levels of greenhouse gases due to human activity as the main influence. This attribution is clearest for the most recent 50 years, for which the most detailed data are available.

Contrasting with the scientific consensus, other hypotheses have been proposed to explain some of the observed increase in global temperatures, including: the warming is within the range of natural variation; the warming is a consequence of coming out of a prior cool period, namely the Little Ice Age; or the warming is primarily a result of variances in solar radiation. [8] None of the effects of forcing are instantaneous. Due to the thermal inertia of the Earth’s oceans and slow responses of other indirect effects, the Earth’s current climate is not in equilibrium with the forcing imposed.

Climate commitment studies indicate that even if greenhouse gases ere stabilized at present day levels, a further warming of about 0. 5 co (0. 9 OF) would still OCCUr. [9] Greenhouse gases in the atmosphere Main article: Greenhouse effect [Pick] Recent increases in atmospheric carbon dioxide (CO). The monthly CO measurements display small seasonal oscillations in an overall yearly uptrend; each years maximum is reached during the northern hemisphere’s late spring, and declines during the northern hemisphere growing season as plants remove some CO from the atmosphere.

The greenhouse effect was discovered by Joseph Fourier in 1824 and was first investigated quantitatively y Savant Awareness in 1896. It is the process by which absorption and emission of infrared radiation by atmospheric gases warms a planet’s atmosphere and surface. Greenhouse gases create a natural greenhouse effect, without which, mean temperatures on Earth would be an estimated 30 DC (54 OF) lower, so that Earth would be uninhabitable. L O] Thus scientists do not “believe in” or “oppose” the greenhouse effect as such; rather, the debate concerns the net effect of the addition of greenhouse gases, while allowing for associated positive and negative feedback mechanisms. On Earth, the major natural greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect (not including clouds); carbon dioxide (CO), which causes 9-26%; methane (CHI), which causes 4-9%; and ozone, which causes 3-?7%. The atmospheric concentrations of CO and CHI have increased by 31% and 149% respectively above pre-industrial levels since 1750.

These levels are considerably higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores. From less direct geological evidence it is believed that CO values this sigh were last attained 20 million years ago. [11 ] “About three-quarters of the anthropogenic [man-made] emissions of CO to the atmosphere during the past 20 years are due to fossil fuel burning. The rest of the anthropogenic emissions are predominantly due to land-use change, especially deforestation. [1 2] The present atmospheric concentration of CO is about 383 parts per million (pimp) by volume. [1 3] Future CO levels are expected to rise due to ongoing burning of fossil fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological, natural placements, but may be ultimately limited by the availability of fossil fuels. The EPIC Special Report on Emissions Scenarios gives a wide range of future CO scenarios, ranging from 541 to 970 pimp by the year 2100. 14] Fossil fuel reserves are sufficient to reach this level and continue emissions past 2100, if coal, tar sands or methane accelerates are extensively used. [1 5] Positive feedback effects such as the expected release of CHI from the melting of permafrost peat bogs in Siberia (possibly up to 70,000 million tones) may lead to significant additional sources of greenhouse gas emissions[J not included in climate models cited by the EPIC. [I] Feedbacks The effects of forcing agents on the climate are complicated by various feedback processes. One of the most pronounced feedback effects relates to the evaporation of water.

CO injected into the atmosphere causes a warming of the atmosphere and the earth’s surface. The warming causes more water to be evaporated into the atmosphere. Since water vapor itself acts as a greenhouse gas, this causes still more warming the warming causes more water vapor to be evaporated, and so forth until a new dynamic equilibrium concentration of water vapor is reached at a slight increase in immunity and with a much larger greenhouse effect than that due to CO alone. CO] This feedback effect can only be reversed slowly as CO has a long average atmospheric lifetime.

Feedback effects due to clouds are an area of ongoing research and debate. Seen from below, clouds absorb infrared radiation and so exert a warming effect. Seen from above, the same clouds reflect sun light and so exert a cooling effect. Increased global water vapor concentration may or may not cause an increase in global average cloud cover. The net effect of clouds thus has not been well modeled, however, loud feedback is second only to water vapor feedback and is positive in all the models that contributed to the EPIC Fourth Assessment Report. 1 7] Another important feedback process is ice-lobed feedback. [18] The increased CO in the atmosphere warms the Earth’s surface and leads to melting of ice near the poles. As the ice melts, land or open water takes its place. Both land and open water are on average less reflective than ice, and thus absorb more solar radiation. This causes more warming, which in turn causes more melting, and this cycle continues. Positive feedback due to lease of CO and CHI from thawing permafrost is an additional mechanism contributing to warming.

Possible positive feedback due to CHI release from melting seabed ices is a further mechanism to be considered. Effects of global warming From Wisped, the free encyclopedia Jump to: navigation, search Further information: Global warming The net impact of global warming so far has been modest, but near-future effects are likely to become significantly negative, with large-scale extreme impacts possible by the end of the century. The predicted effects for the environment and for human life are numerous and varied. The main effect is an increasing global average temperature.

From this flow a variety of resulting effects, namely, rising sea levels, altered patterns of agriculture, increased extreme weather events, and the expansion of the range of tropical diseases. In some cases, the effects may already be occurring, although it is generally difficult to attribute specific natural phenomena to long-term global warming. A summary of possible effects and our current understanding can be found in the report of the Intergovernmental Panel on Climate Change (EPIC) Working Group a discussion of projected climate changes is found n Working Group 1. 2] The more recent EPIC Fourth Assessment Report outlines the latest agreed international thinking. Scientific and business groups in individual countries are also producing reports on the effects of global warming on their nation, such as in Australia. Proposed responses to the effects of global warming include mitigation and adaptation. [pick][edit] Overview Projected climate changes due to global warming have the potential to lead to future large-scale and possibly irreversible changes in our climate resulting in impacts at continental and global scales.

Examples Of projected climate hanged include: ; significant slowing of the ocean circulation that transports warm water to the North Atlantic, ; large reductions in the Greenland and West Antarctic Ice Sheets, ; accelerated global warming due to carbon cycle feedbacks in the terrestrial biosphere, and ; releases of terrestrial carbon from permafrost regions and methane from hydrates in coastal sediments. The likelihood, magnitude, and timing of many of these changes is uncertain. However, the probability of one or more of these changes occurring is likely to increase with the rate, magnitude, and duration of climate change.

Additionally, the United States National Academy of Sciences has warned, “greenhouse warming and other human alterations of the earth system may increase the possibility of large, abrupt, and unwelcome regional or global climatic events…. Future abrupt changes cannot be predicted with confidence, and climate surprises are to be It is not possible to be certain whether there will be any positive benefits of global warming. What is known is that some significant negative impacts are projected and these drive most of the concern about global warming and motivates attempts to taiga or adapt to the effects of global warming.

Almost all scientists agree, however, that the negative effects would outweigh the positive effects. [citation needed] Most of the consequences of global warming would result from one of three physical changes: sea level rise, higher local temperatures, and changes in rainfall patterns. Sea level is generally expected to rise 18-59 CM by the end of the century. [4] [edit] Effects on weather Global warming is responsible in part for some trends in natural disasters such as extreme weather. Pascal Peddled (2004) “Is climate change increasing he frequency of hazardous events? Environment Times UNEVEN/GRID-Arena Increasing temperature is likely to lead to increasing precipitation [5] [6] but the effects on storms are less clear. Extraterritorial storms partly depend on the temperature gradient, which is predicted to weaken in the northern hemisphere as the polar region warms more than the rest of the hemisphere [edit] More extreme weather This image shows the conclusions of Knutson and Tuttle (2004) that maximum intensity reached by tropical Storms is likely to undergo an increase, with a significant increase in the number of highly destructive étagère 5 storms.

Storm strength leading to extreme weather is increasing, such as the Emanuel (2005) “power dissipation index” of hurricane intensity. Kerry Emmanuel in Nature writes that hurricane power dissipation is highly correlated with temperature, reflecting global warming. Hurricane modeling has produced similar results, finding that hurricanes, simulated under warmer, high-CO conditions, are more intense than under present-day conditions; there is less confidence in projections of a global decrease in numbers of hurricanes.

Worldwide, the proportion of hurricanes caching categories 4 or 5 – with wind speeds above 56 meters per second – has risen from 20% in the 1 sass to 35% in the 1 sass. [9] Precipitation hitting the US from hurricanes increased by 7% over the twentieth century [10]. See also Time Magazine’s “Global Warming: The Culprit? ” and [1]. (The extent to which this is due to global warming as opposed to the Atlantic Multilateral Oscillation is unclear. ) Catastrophes resulting from extreme weather are exacerbated by increasing population densities. The World Meteorological Organization[2] and the U.

S. Environmental Protection Agency [3] have linked increasing extreme weather events to global warming, as have Hoys et al. (2006), writing that the increasing number of category 4 and 5 hurricanes is directly linked to increasing temperatures. [4] Thomas Knutson and Robert E. Tuttle of the NOAA stated in 2004 that warming induced by greenhouse gas may lead to increasing occurrence of highly destructive category-5 storms. [5] Vichy and Sodden find that wind shear, the increase of which acts to inhibit tropical cyclones, also changes in model-projections of global warming.

There are projected increases of wind shear in the tropical Atlantic and East Pacific associated with the deceleration of the Walker circulation, as well as decreases of wind shear in the western and central Pacific[6]. The study does not make claims about the net effect on Atlantic and East Pacific hurricanes of the warming and moistening atmospheres, and the model-projected increases in Atlantic wind shear. [1 1 ] A substantially higher risk of extreme weather does not necessarily mean a noticeably greater risk of slightly-above- average weather[1 2].

However, the evidence is clear that severe weather and moderate rainfall are also increasing. Stephen Mackinaw, national co- radiator of the Centre for Energy, Environment, Science and Technology – which prepared the Tanzania government’s climate change report to the UN – says that change is happening in Tanzania right now. “In the past, we had a drought about every 10 years”, he says. “Now we just don’t know when they will come. They are more frequent, but then so are floods. The climate is far less predictable. We might have floods in May or droughts every three years.

Upland areas, which were never affected by mosquitoes, now are. Water levels are decreasing every day. The rains come at the wrong time for farmers ND it is leading to many problems”[1 3]. Greg Holland, director of the Mescals and Microscope Meteorology Division at the National Center for Atmospheric Research in Boulder, Colorado, said on April 24, 2006, “The hurricanes we are seeing are indeed a direct result of climate change,” and that the wind and warmer water conditions that fuel storms when they form in the Caribbean are, “increasingly due to greenhouse gases.

There seems to be no other conclusion you can logically draw. ” Holland said, “The large bulk of the scientific community say what we are seeing now is linked directly to roundhouse gases. ” [14] (See also “Global warming? ‘ in tropical cyclone) [edit] Increased evaporation Increasing water vapor at Boulder, Colorado. Over the course of the 20th century, evaporation rates have reduced worldwide [1 5]; this is thought by many to be explained by global dimming. As the climate grows warmer and the causes of global dimming are reduced, evaporation will increase due to warmer oceans.

Because the world is a closed system this will cause heavier rainfall and more erosion, and in more vulnerable tropical areas (especially in Africa), desertification due to deforestation. Many scientists think that it could result in more extreme weather as global warming progresses. The EPIC Third Annual Report says: “… Global average water vapor concentration and precipitation are projected to increase during the 21 SST century. By the second half of the 21 SST century, it is likely that precipitation will have increased over northern mid- to high latitudes and Antarctica in winter.

At low latitudes there are both regional increases and decreases over land areas. Larger year to year variations in precipitation are very likely over most areas where an increase in mean reciprocation is projected” [16] [17]. [edit] Cost Of more extreme weather Choc and Fisher, writing in Climate Change, Volvo. 58 (2003) up. 149, predict that each 1% increase in annual precipitation would enlarge the cost of catastrophic storms by 2. 8%. The Association of British Insurers has stated that limiting carbon emissions would avoid of the projected additional annual cost optically cyclones by the sass.

The cost is also increasing partly because of building in exposed areas such as coasts and floodplains. The ABA claims that reduction of the vulnerability to some inevitable impacts f climate change, for example through more resilient buildings and improved flood defenses, could also result in considerable cost-savings in the longer. [1 8] [edit] Desalination of local climates The first recorded South Atlantic hurricane, “Catalina”, which hit Brazil in March 2004 In the northern hemisphere, the southern part of the Arctic region (home to people) has experienced a temperature rise 1 co to 3 co (1. 8 OF to 5. OF) over the last 50 years. Canada, Alaska and Russia are experiencing initial melting of permafrost. This may disrupt ecosystems and y increasing bacterial activity in the soil lead to these areas becoming carbon sources instead of carbon sinks [19]. A study (published in Science) of changes to eastern Siberian permafrost suggests that it is gradually disappearing in the southern regions, leading to the loss of nearly 1 1% of Siberian nearly 11,000 lakes since 1 971 [20]. At the same time, western Siberia is at the initial stage where melting permafrost is creating new lakes, which will eventually start disappearing as in the east.

Western Siberia is the world’s largest peat bog, and the melting of its permafrost is likely to lead to he release, over decades, of large quantities of methane-?creating an additional source of greenhouse gas emissions [21]. Hurricanes were thought to be an entirely North Atlantic phenomenon. In April 2004, the first Atlantic hurricane to form south of the Equator hit Brazil with 40 m/s (144 km/h) winds; monitoring systems may have to be extended 1 ,600 km (1 000 miles) further south [22]. [edit] Oceans [edit] Sea level rise Sea level has been rising 0. CM/year, based on measurements of sea level rise from 23 long tide gauge records in geologically stable environments Main article: Sea level rise With increasing average global temperature, the water in the oceans expands in volume, and additional water enters them which had previously been locked up on land in glaciers, for example, the Greenland and the Antarctic ice sheets. An increase of 1. 5 to 4. 5 co is estimated to lead to an increase of 15 to 95 CM (EPIC 2001 The sea level has risen more than 120 meters since the peak of the last ice age about 18,000 years ago.

The bulk of that occurred before 6000 years ago. From 3000 years ago to the start of the 1 9th century, sea level was almost constant, rising at 0. 1 to 0. 2 mm/yr; since 1 900, the level as risen at 1-2 mm/yr [23]; since 1 992, satellite altimeter from TOPE/ Poseidon indicates a rate of about 3 mm/yr [24]. The Independent reported in December 2006 that the first island claimed by rising sea levels caused by global warming was Lockhart Island in the Sandbars in Bay of Bengal.

Lockhart was home to Earlier reports suggested that it was permanently flooded in the sass due to a variety of causes[26], that other islands were also affected and that the population in the Sandbars had more than tripled to over 4 million. [27] [edit] Temperature rise The temperature of the Antarctic Southern Ocean rose by 0. 7 c (0. 31 OF) between the sass and the sass, nearly twice the rate for the world’s oceans as a whole [28]. As well as effects on ecosystems (e. G. Y melting sea ice, affecting algae that grow on its underside), warming could reduce the ocean’s ability to absorb CO. More important for the United States may be the temperature rise in the Gulf of Mexico. As hurricanes cross the warm Loop Current coming up from South America, they can gain great strength in under a day (as did Hurricane Strain and Hurricane Rata in 2005), with water above 85 seemingly promoting Category 5 storms. Hurricane season ends in November as the waters cool. Edit] Ecosystems Rising temperatures are beginning to have a noticeable impact on birds. Secondary evidence of global warming -? lessened snow cover, rising sea levels, weather changes -? provides examples of consequences of global warming that may influence not only human activities but also the ecosystems. Increasing global temperature means that ecosystems will change; some species are being forced out of their habitats (possibly to extinction) because of changing conditions, while others are flourishing.

Few of the terrestrial secretions on Earth could expect to be unaffected. Many of the species at risk are arctic and Antarctic fauna such as polar bears, emperor penguins, many salt wetland flora and fauna species, and any species that inhabit the low land areas near the sea. Species that rely on cold weather conditions such as gyrfalcons, and snowy owls that prey on lemmings that use the cold winter to their advantage will be hit hard. [citation needed] Butterflies have shifted their ranges northward by 200 km in Europe and North America.

Plants lag behind, and larger animals’ migration is slowed down by cities and highways. In Britain, spring butterflies are appearing an average of 6 days earlier than two decades ago [35]. In the Arctic, the waters of Hudson Bay are Ice-free for three weeks longer than they were thirty years ago, affecting polar bears, which prefer to hunt on sea ice. [36]. Two 2002 studies in Nature (Volvo 421 ) [37] surveyed the scientific literature to find recent changes in range or seasonal behavior by plant and animal species.

Of species showing recent change, 4 out Of 5 shifted their ranges towards the poles or higher altitudes, creating “refugee species”. Frogs were breeding, flowers blossoming and birds migrating an average 2. 3 days earlier each aced; butterflies, birds and plants moving towards the poles by 6. 1 km per decade [38]. A 2005 study concludes human activity is the cause of the temperature rise and resultant changing species behavior, and links these effects with the predictions of climate models to provide validation for them [39].

Grass has become established in Antarctica for the first time. [40] Forests in some regions potentially face an increased risk of forest fires. The ID-year average of boreal forest burned in North America, after several decades of around 10,000 km (2. 5 million acres), has increased steadily since 970 to more than 28,000 kern (7 million acres) annually. [41]. This change may be due in part to changes in forest management practices. Also note forest fires since 1997 in Indonesia. The fires are started to clear forest for agriculture.

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