Global warming refers to a slow but sustained rise in the average temperatures of the air near the surface of the Earth. Global warming is a natural phenomenon which rendered the earth habitable due to rise in temperature. However, the current global warming we are experiencing is due to fast, unnatural increase in temperatures that threatens to change climate rapidly to harmful levels. The heating of the Earth surface is necessitated by the heat produced by the sun and which travels through the atmosphere. As the earth’s surface warms, heat energy rises into the space. Gases present in the atmosphere absorb this rising heat energy and redirects it back towards the surface, this is called the greenhouse effect. The atmosphere acts as a blanket which traps heat radiating from the earths surface. An increase in greenhouse gases in the atmosphere ensures heat is tapped within the atmosphere hindering its loss to the outer space. Greenhouse gases include vapor, carbon dioxide and nitrous oxide. Relatively small increases in these gases force more heat to be trapped and thus increase in temperatures. Carbon dioxide and methane gases have long residence time in the atmosphere stretching to decades compared to water vapor which lasts for only a few days. Presence of dust and aerosol chemicals causes a cooling effect in the atmosphere even in very small quantities.
The earth’s temperatures have gone through various climate cycles but in the last 10-11000 years the greenhouse and in effect earth temperatures and climate have remained relatively stable. This is the period when civilization of men started with the agrarian revolution, growth of cities and invention of machines. This saw gradual increase in the amount of carbon dioxide and other greenhouse gases causing a warming effect which continues up to date. Carbon dioxide current level is 385 part per million which is the greatest recorded so far. Temperature has also been increasing rapidly with a recorded 1 degree F between mid nineteenth to the end of the twentieth Century. An increase of about 0.50 C has also been recorded fort the past 25 years with the total heating from the late 19th century to 2005 being o.80 C. This has resulted in to many effects to the environment and humans and animals. The graph below shows temperature increases over the past centuries from 900 AD to 2000.
Effects of global warming on tropical regions
Tropical regions are areas that lie between the Tropic of Cancer in the northern hemisphere at approximately 23026’N and the Tropic of Capricorn in the southern hemisphere at approximately 23026’S. Here the sun reaches a point directly overhead and a point straight beneath at least once in a solar year. These will experience effects from global warming as discussed below.
Major shifts in ocean fisheries distribution is one of the most significant effect from global warming and climate change. Productivity of world’s fisheries will shift to other regions as a result of change in their ecosystems. Warmer waters attract fish populations to colder regions and warmer environment will create inhospitable conditions for species that cannot move to new regions leading to their extinction. This leads to loss of staple diets to the communities, which rely on them and this might lead to change of their cultures. Projections by researchers from University of British Columbia and Princeton show that climate change will lead to a drop of 40% fish catch in the tropics and an increase of 30-70% in catch potential in high latitude regions. This will lead to food insecurity in the tropic regions.
Climate change has resulted in changes in ocean conditions such as temperature and current patterns. These changes have directly affected the population and locations of different species of fish. This has resulted in large scale movement of fish towards the pole leading to tropical countries losing big fish catches and invasion and local extinction of some species which will eventually lead to disruption in marine ecosystems and biodiversity according to research by scientists from Universities of British Columbia, Princeton and East Anglia.
Climate change impacts fisheries in various ways both directly and indirectly depending on the type of ecosystem and fishery. inland fisheries will be severely affected by changing water levels and flooding events while coastal marine fisheries will be affected by rising water temperatures which will impact the sensitive ecosystems the depend on. Some of the ways include: changes in temperature affect the aquatic ecology by changing ocean currents, coral bleaching, disruption of fish reproductive patterns and migratory paths; changes in hydrology of inland waters as a result of changes in precipitation and evapotranspiration. This results in disrupted river flows, flood timing and the extent of the floods. These in turn affects fish reproduction, mortality and growth; changes in temperature will also result in rise in frequency of extreme events such as hurricanes and typhoons. These will lead to wasted fishing time, loss of nets, damage to boats and shore facilities, loss of life and destruction of coastal communities.
Coral reef changes
This is am major source of ecosystem goods and services to small island states in the tropics. Healthy corals are filled with life, sounds and activity as thousands of fish and invertebrates species inhabit them, but, currently few coral reefs are this abundant in species as they were a few decades ago. Surveys from 1960s and 19970s show that coral cover on undisturbed reefs was 70% or higher, however, in recent times coral loss on individual reefs is widespread even on the isolated and managed reefs such as.
Florida Keys and unpublished recent surveys show pacific coral reef cover to be about 30% which could be half of what it was a few decades ago.Climate change has been indicated as the main cause of coral loss. Coral loss is caused by coral bleaching which degrades the coral reef. Acid rain which is a result of accumulation of carbon dioxide in the atmosphere causes coral acidification.
Coral bleaching happens when the symbiotic relationship between coral animal and a plant like organism, zooxanthellae breaks due to rise in the normal ocean temperature and the coral dies. Zooxanthellae contain photosynthetic pigments which it uses to make food and oxygen for coral in return for nutrients. The greater the rise in temperature and the longer the time for the rise, the higher the mortality rate of coral which turns coral white due to loss of zooxanthellae. Global warming has led to 10 increases in ocean temperature for the last couple of decades which have resulted to severe coral loss.
Global warming has resulted in ocean warming which has led to increased incidences of infectious diseases which cause most coral deaths particularly in the tropical areas of the Caribbean. The severity of these diseases such as the white syndrome increases with rise in temperatures. White syndrome is a condition that leads to a disease on the coral reef and is caused by prevalence of relatively warm conditions over the years.
The increased presence of carbon dioxide gas concentration in the atmosphere, mostly as a result of increased human activities, usually results in absorption of the gas into the ocean waters leading to acidification of the water. Low Ocean PH slows down the growth of coral and their ability to compete with other species like seaweed and sponges. Temperatures are predicted by IPCC 4th assessment to increase by 1-40 C in the next few decades. This poses a major threat to coral reefs because it means temperatures will be beyond their tolerance levels which will lead to mass mortality.
Global warming has led to rise in the sea level as the ice sheets and glacier in the Polar Regions melt. This will lead to increased incidences of tropical storms through the elevation of the base of storm surges. Global warming will also impact weather events such as ENSO which in turn influence tropical storms. During the past 50 years an IPCC report have revealed that heat waves and intense rain events have increased in frequency with human induced global warming is the culprit. During this time tropical rain intensified which were received in form of large storms or light rainfall rather than moderate storms as experienced before. Incidences of cyclones and hurricanes have increased between 1979 and 2003.
Dislocation of Asian Communities
More than 10% of world population lives in coastal areas less than 10 meters above sea level according to IPCC. Sea levels are estimated to rise by about 0.1 and 0.5 meters by 2099 as a result of increase in sea water and melting glaciers9. This means that communities living in vulnerable countries in Asia such as Bangladesh, Philippines and small islands such as Tuvalu, Maldives and Solomon islands will be prone to storm damage and sea level rise. These coastal communities have experienced loss of their livelihoods as fisheries and crops are destroyed and their homes flooded. Drinking water has also been affected as sea water penetrates their drinking water sources.
United Nations Development Program
It has supported projects to help small communities cope with the effects of climate change as a result of global warming such as erosion, sea level rise and unpredictable rainfall. It has established a program referred to as Community Based Adaptation (CBA) scheme together with Global Environment Facility (GEF).
The scheme provides technical support to communities on the potential ways they could deal with climate change.
The scheme has projects in Jamaica blue mountain region which deal with erosion, Kazakhstan dealing with effects of drought, Samoa dealing with coastal flooding and drought, Bangladesh, Bolivia, Guatemala, Morocco, Namibia, Niger and Vietnam.
Catholic Agency for Overseas Development (CAFOD)
This is an agency supported by the Catholic church of England and Wales which provide relief to human suffering. The agencies sponsors held talks with world leaders and climate change experts in New York last September before the commencement of UN summit. In Bangladesh the organization is partnering with local organizations to reduce disaster risks of coastal flooding using a community focused approach. The program raises awareness in government and people about what can be tackled.
In these projects they encourage farmers to grow crops that can do well in both saline and fresh water and plant coconut trees along roads to prevent floods and provide food and building materials.
Effects of global warming in Polar Regions
Polar region are the areas around the poles of the earth. The Arctic region extends from 66 degrees 33’ latitude in the northern hemisphere and the Antarctic 66 degrees 33’ latitude in the southern hemisphere. These regions are covered with great masses of ice.
As a result of global warming, the average temperatures of the arctic region are increasing twice as fast as the temperatures elsewhere. In Alaska in US, temperature rise of 30C has been reported between 1970 and 2000 and the Greenland’s extensive ice sheet is melting as a result of temperature increases. NASA has also put the reduction of permanent ice cover at 9% each decade which could lead to ice-free summers by the end of the century.
As a result of thawing ice some species of both plants and animals are moving north ward in search of cooler temperatures. Melting of the Ward Hunt ice shelf which enclosed a rare freshwater lake caused the lake to drain in the sea. This destroyed the ecosystem which supported whales, polar bears and native communities.
Thawing permafrost may result to pools of water collecting where there was no water before. This will destroy habitats for the plants and wildlife therein as they drawn and become waterlogged and therefore die or migrate to other areas.
Permafrost in the tundra
In Polar Regions soil layer is permanently frozen and this is what is called permafrost. In Polar Regions permafrost does not thaw and goes to a depth of ten or more feet. This means in northern latitudes infrastructure such as homes, roads and buildings among others are built on permafrost. Due to global warming, permafrost has started to thaw leading to collapse of such infrastructure and erosion example is the Canadian coastline. Thawing of permafrost can result to floods in both human habited and wildlife habitats. This will also alter the hydrological cycle of such areas.
Ocean water levels
Scientists predict that there would be 3 foot sea-level rise by 2100 as a result of melting glaciers and ice sheets in the Polar Regions. This is a threat to low laying islands such as the Maldives, Solomon Islands and cities such as Shanghai which will experience massive dislocation of their populace and disruption or total loss of lifestyles. In US, the Environmental Protection Agency estimates the land that would be inundated to be 22,400 square miles by 2100 along the Atlantic and Gulf coasts.
The Chernobyl nuclear disaster
The disaster occurred in a nuclear power station 18 km northwest of Chernobyl city in Ukraine in 1986. This happened when the operating crew was trying to test a turbine under construction, which without warning, produced a series of incidences and
reactions which caused an explosion that released clouds of radiation into the air. The cause of this failure was linked to reactor design defects and operator faults leading to release of 50 tones of radioactive particles.
The immediate deaths were 54 people with estimated deaths as a result of the accident put at 4000-24,000 by the Chernobyl forum in a report in 2005. The Greenpeace on the other hand estimates 93,000 eventual deaths as a result of the accident which they base on data they obtained from the Belarus National Academy of Sciences.
It is estimated that 270,000 people in the region will develop cancer as a result of exposure to nuclear radiation. There are already 1800 thyroid cancers cases reported of the children who were between 0-1 years during the time of the disaster. Psychological effects are the biggest health impacts of the disaster as many people turned to drinking or suicide. The UNDP also noted that as a result of the accident people consider themselves as victims and be passive in the decisions on their future as opposed to taking proactive actions to self-sufficiency. Other health effects identified are premature births, metal illnesses in children and birth defects.
Besides long-term effects on health of people, mutations on both plants and animals are also evident with leaves even changing shape and deformities in animals.
The world has now become more aware and vigilant on the safety of nuclear power and the design of reactors. The scientists have also investigated effects of radioactive pollution and the safest and efficient procedures for cleaning up radioactive waste and how to prevent disasters from happening.
Attempt to mitigate the damage
The reactor which ailed contained radioactive materials which were of potential danger. To prevent exposure, a shield called sarcophagus was constructed to cover for 30 years. Since it is collapsing, another one in under construction at a cost of $1.1 billion to shield it for another 100 years.
Acid deposition is a phenomenon that occurs when emissions from industrial processes and combustion of carbon based fuels are released into the atmosphere where, they undergo a series of chemical reactions and the products fall to the earth as deposits either through rain water (acid rain) or snow fall.
Source of pollutant
The main pollutants that lead to acid deposition are the sulfur dioxide (SO2) and nitrogen Oxide (NOx). These two chemicals react with water, oxygen; carbon dioxide and sunlight produce sulfuric (H2SO4) and nitric (HNO3) acids which cause acid deposition. Sulfur dioxide originates from burning of fossil fuels such as peat, oil and coal in automobiles, power plants among others, which contain sulfur and natural phenomena such as volcanic eruptions.
Nitrogen Oxide on the other hand is emitted from natural processes in plant and animal growth and anthropogenic sources where combustion of fossil fuels occurs such as transportation, industrial processes etc.
Impacts of acid deposition
Acid deposition either in snow or acid rain causes depletion of nutrients from the soil through a process known as leaching. The nutrients are used in neutralizing of acids therefore forming complex compounds where these nutrients are not available to plants. This makes trees weaker and more vulnerable to diseases. The loss of the Pennsylvania sugar maples and red spruce attributed to chronic acidification.
Acid deposition is also the cause of aluminum toxicity. This heavy metal is released from the soil as a result of reactions between acid compounds and soil minerals and carried through runoff to wetlands. This creates inhospitable conditions for freshwater fish species, which is causing their extinction.
Eutrophication of aquatic ecosystems is another consequence of acid deposition. Nitric acid deposited reaches the aquatic systems, which enrich them with nitrogen encouraging growth of algae that sucks in oxygen from the water. The low oxygen condition has resulted to fish and shellfish deaths and threatens the biodiversity of the aquatic systems.
Strategies to mitigate acid deposition are as follows
Coal washing is a process of removing sulfur before combustion of fuels is done. This method is not a 100% effective and will result in pollution f water sources.
Fuel switching from carbon based fuels (coal, oil and peat) to clean and renewable sources of fuel such as wind energy, wave’s energy and solar energy. These are expensive ventures, which will require governments to invest heavily on and change their policies. These are also likely to generate a lot of politics.
Installation of scrubbers in industrial plants to direct waste to the high atmosphere is another way of mitigating acid deposition. This is quite effective but would not be feasible in old plants built before the law requiring for the same was passed. Moreover countries can also seek for alternative power plants and reduce consumption of fuels. These will require major energy policy shifts.
A fuel cycle is the chain of industrial processes which entail the production of electricity from a particular fuel in power stations. This affects the relative cost of power production in it shows the most suitable fuel or cycle for either baseloaded or peaking units generations for which utilization of the capital investment is efficient. Below is an illustration of nuclear fuel cycle from uranium mining to waste disposal adapted from World Nuclear association 1995.
The types of pollution generated
These are categorized as low-level which are produced at processes of th fuel cycle; intermediate-level waste which is generated during the reactor operation and in reprocessing stage; and high-level waste generated at the reprocessing stage and in the used fuel and is composed of fission products.
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