Krishnan's Blog

Chlorofluorocarbons, commonly known as CFCs, are a group of man-made compounds containing chlorine, fluorine and carbon. They are not found anywhere in nature. The production of CFCs began in the 1930s for the purpose of refrigeration. Since then they have been extensively utilised as propellants in aerosols, as blowing agents in foam manufacture and in air conditioning. There are no removal processes or sinks for CFCs in the lowest part of the atmosphere called the troposphere. As a result they are transported up into the stratosphere, between 10 to 50 km above the Earth's surface, where they are broken down by ultraviolet (UV) radiation from the Sun, releasing free chlorine atoms which cause significant ozone depletion . Although the amounts of CFCs in the atmosphere are very small, measured in parts per trillion (million million), they do contribute significantly to the enhancement of the natural greenhouse effect , because they are very good at trapping heat. Molecule for mo...

A change in global climate would be accompanied by shifts in climatic zones, thereby altering the suitability of a region for the growth of distinctive species. Trees in particular have long reproductive cycles, and many species may not be able to respond to the climatic changes quickly enough. A shift in climatic zones not only affects the vegetation but also affects the incidence of tree pests such as insects and diseases. These pests have less difficulty in migrating with their climatic zones than vegetation and may damage tree species with lower immunity. As well as the effects of temperature and precipitation variations, and changes to weather patterns, forest growth may also respond to increased atmospheric concentrations of carbon dioxide. Studies with immature forest plantations suggest that an increase in atmospheric carbon dioxide would be beneficial to tree growth. The elevated carbon dioxide concentrations enhance photosynthesis rates with increased utilisation of carb...

The Sun, which is the Earth's only external form of heat, emits solar radiation mainly in the form of shortwave visible and ultraviolet (UV) energy. As this radiation travels toward the Earth, 25% of it is absorbed by the atmosphere and 25% is reflected by the clouds back into space. The remaining radiation travels unimpeded to the Earth and heats its surface. The Earth releases a lot of energy it has received from the Sun back to space. However, the Earth is much cooler than the Sun, so the energy re-emitted from the Earth's surface is much weaker, in the form of invisible longwave infrared (IR) radiation, sometimes called heat. Greenhouse gases like water vapour, carbon dioxide , methane and nitrous oxide trap the infrared radiation released by the Earth's surface. The atmosphere acts like the glass in a greenhouse, allowing much of the shortwave solar radiation to travel through unimpeded, but trapping a lot of the longwave heat energy trying to escape back to space...

Climate is the most significant factor in determining plant growth and productivity. Without intervention to reduce emissions of greenhouse gases, global average surface temperature is projected to increase by about 0.2°C per decade during the 21st century. This rapid change in climate will have major implications for agriculture around the world. Crop growth is often limited by temperature. Temperatures during the 21st century are expected to increase more in the higher latitudes where shifts in vegetation will be greater. In Britain an increase in temperature of 1.5°C by 2050 is the equivalent of a decrease in altitude of approximately 200m. This is the same as a shift southward in latitude of 200-300 km. Such an increase in temperature would allow widespread maize cultivation across southern England to take place. In other regions however, a rise in temperature may not be so beneficial. Small increases in temperature would extend the range of temperature-limited pests. The European ...

Carbon dioxide (CO 2 ) is a colourless, odourless gas consisting of molecules of two oxygen atoms and one carbon atom. Carbon dioxide is produced when any form of carbon or almost any carbon compound is burned in an excess of oxygen. For example, it is released into the atmosphere during natural forest fires and the man-made combustion of fossil fuels . Other natural sources of carbon dioxide include volcanic eruptions, decay of dead plant and animal matter, evaporation from the oceans and respiration (breathing). Carbon dioxide is removed from the atmosphere by carbon dioxide "sinks". The main removal processes are absorption by seawater, and utilisation (for photosynthesis) by ocean-dwelling plankton and land-dwelling biomass, including forests and grasslands. Through Earth history the amount of carbon dioxide in the atmosphere has varied significantly. The Earth's early atmosphere was probably composed mostly of carbon dioxide. At that time, the natural greenhouse e...

Although we are currently concerned about global warming caused by mankind's enhancement of the natural greenhouse effect through greenhouse gas pollution, the Earth's climate has fluctuated many times in the past in response to natural mechanisms of climate change. Such changes in global climate have also occurred over much longer time scales, from hundreds and thousands of years to millions and hundreds of millions of years. In fact the current global warming trend which began at the end of the 19 th century spans only a tiny fraction of the Earth's climatic history. Taking a longer perspective on climate variability can help us gain a better understanding of the global climate and of the evolution of the climate today and in the future. The overall state of the global climate is largely determined by balance between energy the Earth receives from the Sun and the heat which the Earth releases back to space, called the global energy balance. Many causes of climate ch...

One of the impacts which global warming may have on the surface of the Earth is to exacerbate the worldwide problem of desertification. A decrease in the total amount of rainfall in arid and semi-arid areas could increase the total area of drylands worldwide, and thus the total amount of land potentially at risk from desertification. Desertification was defined at the Rio Earth Summit in 1992 as "land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors including climatic variations and human activities". Desertification involves the depletion of vegetation and soils. Land degradation occurs all over the world, but it is only referred to as desertification when it takes place in drylands. This is because these areas are especially prone to more permanent damage as different areas of degraded land spread and merge together to form desert-like conditions. Global warming brought about by increasing greenhouse gas levels in the atmosphere is...

Everyone contributes to global emissions of greenhouse gases , but it is not only governments which can take action to reduce the threat of global warming. We all use energy for heating our homes, running electrical appliances, cooking food and driving our cars. Most of this energy comes from the burning of fossil fuels , such as oil, coal and gas, which release carbon dioxide , the main greenhouse gas, into the atmosphere. Despite uncertainties, the general scientific consensus is that increased levels of greenhouse gases as a result of mankind's activities are enhancing the Earth's natural greenhouse effect and causing global warming. Energy use is responsible for about 75% of man-made carbon dioxide emissions. Therefore, it is important to try to reduce our dependence on fossil fuels and reduce energy consumption. Energy used in the home can be saved by a number of measures, including draught proofing, insulation, and using energy efficient lighting and other household ...

During the 20 th century , the global climate has warmed by about 0.6°C, or about 0.06°C per decade. Computer models which simulate the effects on climate of increasing atmospheric greenhouse gas concentrations project that global average surface temperatures will rise by a further 3°C by the end of the 21 st century , or 0.3°C per decade. It is currently believed that most ecosystems can withstand at most a 0.1°C global temperature change per decade, before experiencing severe ecological stresses, leading in some cases to species extinction. A warming of even 2°C over the next 100 years would shift current climate zones in temperate regions of the world about 300 km towards higher latitudes, and vertically by 300 m. The composition and geographical distribution of unmanaged ecosystems will change as individual species respond to new conditions. At the same time, habitats will be degraded and fragmented by the combination of climate change, deforestation , desertification and ot...

Forests cover around a quarter to a third of the total land surface of the Earth. The reduction in area of this valuable environmental, social and economic resource through deforestation has the potential to cause problems on a global scale. Climate models have demonstrated a clear link between deforestation and climate change. Deforestation is the process of changing land use from forestry to a non-forest use. Western Europe has already lost over 99% of its primary forest. Today, deforestation programmes focus on the major rainforests of the tropics. In the 1980s global deforestation was estimated at 17 to 20 million hectares per year, equivalent to the size of Britain. Current tropical tree planting programmes are not keeping pace with this rate of deforestation. Countries in these areas are often under-developed and striving for improved economies. Deforestation for wood and agricultural land can provide numerous economic benefits, but can have damaging environmental impacts on ...

"With electronic items high on Christmas shopping lists, a new report is calling on the government to ensure that manufacturers collect and recycle unwanted computers and mobile phones to protect environmental and human health. "This is the motherboard of all problems. Federal and state governments must act to stop the dumping of millions of electronic items in landfill each year," says Jeff Angel, director of the Total Environment Centre (TEC), an independent Australian green organisation. In a report released earlier this month titled ‘Tipping Point: Australia's E-Waste Crisis', the TEC says that by the end of 2008, in excess of 168 million items of electronic waste -- known as e-waste -- will either be in landfills or on their way to be buried in the ground. The problem with this method of disposal, says the TEC's resource conservation campaigner, Jane Castle, is the hazardous legacy that e-waste can create. "There are toxic materials that are leached...

Computers, networking and internet have certainly changed our lives and they way we work. In the 21 st century 99% of the offices have all the above mentioned three great inventions. Every office uses computers networked to each other and also connected to the internet. Every office uses one or more servers for e-mails, hosting websites, FTPs, backups, storage the list goes on and on. No office can function without these boons of technology. Even my office has all these and it helps us function better. But these inventions are destroying our environment. So what can we do, so that our environment is not harmed from the energy that our offices consume. The office complexes use a lot of energy there by inc reasing the energy consumption, which is directly proportional to the burning of fossil fuels (coal). So does that mean, our earth has to die in the hands of technology? Certainly not. The wise usage of electricity in offices can certainly reduce the green house e...

Hansen is director of the Goddard Institute of Space Studies at NASA . Hansen is on of first scientists that warm people about global warming in the 1980. He said if web (human) still produce CO2 will make disaster to our world. By using coal and other fossil fuel , this will increase CO2 concentration on our atmosphere from 385 to 600 parts per million (ppm) in the next 10 year. Major scientists will say that cause of global warming is because human produce CO2, but not for Roy W. Spencer, a research scientist at the University of Alabama in Huntsville. But Spencer views are not shared by most science, including the Intergovernmental Panel on Climate Change , a multinational panel that released updated conclusions about human produced global warming and its risks last year. How To Reduce CO2 Emissions Hansen has some idea and solution for this : 1. Postpone building new coal fired power plant unless they have carbon sequestration technology. 2. Phasing out the use of coal fire ...