In the last century, sea levels rose roughly 7 inches after not having changed noticeably in the previous 2,000 years. Sea levels rising are an effect of global warming and put many states at risk of existing in the near future.
Thursday, February 7, 2013
Tropical rainforests are often called the "lungs of the planet" because they generally draw in carbon dioxide and breathe out oxygen. But the amount of carbon dioxide that rainforests absorb, or produce, varies hugely with year-to-year variations in the climate. In a paper published online Feb 6 2013 by the journal Nature, a team of climate scientists from the University of Exeter, the Met Office-Hadley Centre and the NERC Centre for Ecology & Hydrology, has shown that these variations reveal how vulnerable the rainforest is to climate change.
Friday, February 18, 2011
Thursday, October 15, 2009
Global warming is quite a recent phenomenon that came to international prominence only by the end of the 20th century.
But man-made pollution was known to affect the climate system of the planet as long ago as the middle – end of the 19th century.
It was first suggested in 1863 that changes in the composition of the atmosphere due to pollution could lead to climate change. In 1896 the Swedish scientist Svante Arrhenius made first actual calculations of the effect of greenhouse warming in which he estimated that a doubling of carbon dioxide in the atmosphere would increase the global average temperature by 4 ° C to 6 ° C.
Mechanism of global warming
In order to understand the mechanics of global warming, let’s see how the Earth is “powered” by the Sun (through solar radiation), how the energy (radiation) between these two entities is continuously recycled, and how this cycle maintains the equilibrium temperature of the Earth.
Here is how this process works:
1. The Earth receives its original supply of shortwave radiation from the Sun
2. The Earth then reflects 30% of this solar radiation back into space in its original shortwave form
3. The Earth absorbs the remaining 70% of this solar energy and then re-radiates it back into space in the longwave form (infrared radiation)
4. So in order to maintain thermal equilibrium, the amount of shortwave and longwave radiation leaving the Earth must be equal to the amount of the original shortwave radiation received from the Sun.
Thus, for a certain amount of radiation being exchanged with the Sun the Earth will achieve a certain equilibrium temperature. When there is a change in this equilibrium the problem begins.
The Earth’s atmosphere is a unique environment which consists of a number of naturally occurring gases.
The content of the atmosphere is roughly as follows:
Nitrogen (around 78% of the total)
Oxygen (around 20% of the total)
Water vapor (substantial amount)
Carbon dioxide (small amount)
Trace gases (hydrogen, argon, helium and other gases)
It is exactly some of these gases in the atmosphere (e.g., water vapor and carbon dioxide) that trap the upward-going longwave radiation emitted by the Earth, re-emit it in all directions and thus contribute to the warming of the planet.
The rise in the average temperature of the Earth (i.e. global warming) can take place in 3 ways:
1. An increase in the shortwave solar radiation that enters the atmosphere at the top
2. An increase in the percentage of the radiation that actually reaches the surface through the atmosphere (currently 70% of the total solar radiation), and
3. An increase in the concentration of the greenhouse gases in the atmosphere
The main fundamental causes of global warming are two-fold:
*The first one is our total dependence on the burning of fossil fuels to generate energy to power our industrialized lifestyles.
*The second one is the way we use our land to produce food, timber products etc.
These economic activities are the major drivers of an increase of greenhouse gas concentrations in the Earth's atmosphere.
The Green house gases are the main culprits of the global warming. The green house gases like carbon dioxide, methane, and nitrous oxide are playing hazards in the present times. These green house gases trap heat in earth’s atmosphere and thus result in increasing the temperature of earth. The excessive emission of these gases is the major cause of global warming. Actually green house gasses are the gasses which induces the green house effect. The common known green house gas is carbon-di-oxide.
The major source of carbon dioxide is the power plants. These power plants emit large amounts of carbon dioxide produced from burning of fossil fuels for the purpose of electricity generation. Coal is the major fuel that is burnt in these power plants. Coal produces around 1.7 times as much carbon dioxide per unit of energy when flamed as does natural gas and 1.25 times as much as oil. The coal gives out eighty percent more carbon per unit of energy it produces as compared to natural gas. Another major source of carbon dioxide in the atmosphere is the emission from the cars and other vehicles. About twenty percent of carbon dioxide emitted in the atmosphere comes from burning of gasoline in the engines of the vehicles. This is true for most of the developed countries. Moreover if sports bike and vehicles that are essentially designed for rough terrain, emit more carbon dioxide when used for general purpose on roads. It is always better to use vehicles designed for city driving on the city roads.
The second major greenhouse gas after carbon dioxide, which causes global warming, is Methane. Methane is more than 20 times as effectual as CO2 at entrapping heat in the atmosphere. Methane is obtained from resources such as rice paddies, bovine flatulence, bacteria in bogs and fossil fuel manufacture. Almost in all parts of the world, rice is grown on flooded fields. When fields are flooded, anaerobic situation build up and the organic matter in the soil decays, releasing methane to the atmosphere.
Another major cause of global warming is deforestation. Deforestation is to be blamed for 25% of all carbon dioxide release entering the atmosphere, by the cutting and burning of about 34 million acres of trees each year. Trees collect the CO2 that we breathe out and give away from various other sources, and they give back oxygen that we breathe in. Thus, cutting of trees is leading to greater concentration of carbon dioxide in the atmosphere. Greater urbanization, requirement of land for factories and buildings, requirement of timber are all reasons that are leading to deforestation, which in turn is leading to global warming.
Methane trapped in frozen tundra may be a ticking time bomb. Aparently as much as 400 billion tons of methane may be trapped in the frozen tundra in the Arctic region. This is about 3000 times the current methane content of the atmosphere. Methane is more than 20 times as strong a greenhouse gas as carbon dioxide. The warming and thawing of the tundra may start a chain reaction which could release billions of tons of methane into the atmosphere which would greatly exacerbate the global warming problem.
*Costal ocean temperatures are so high that sea corals are being killed globally.
Up to 90% of corals are dead or dying in many areas.
*The increase in the temperature of the oceans is providing fuel for stronger and more frequent hurricanes and typhoons
*Sea levels are slowly increasing, threatening cities such as Venice, Italy to a greater extent.
*In Montana's Glacier National Park only 27 of the 150 glaciers which existed in 1910 remain today and they will be gone in only 20 years.
*In Canada, polar bears are starving because Hudson's Bay is ice-free too long each year so they cannot catch enough seals to survive.
*Frogs are dying all over the world - not just a few frogs here and there but WHOLE SPECIES are dying off FAST.
*NASA satellite data shows that Solar radiation reaching the Earth is 0.036 percent warmer than it was in 1986.
*Confirmed by a Swiss/German research team whose data shows that the sun is brighter now than 100 - 150 years ago.
The major effect which could be felt by all of us is due to global warming is the un-bearable heat.
The earth has heated up extremely to a high temperature that in future no life can survive. It has changed the life style of the people considerably. We can visibly see a lot of polluted air in our own Chennai city sometimes making breathless! We also need to know few serious effects of global warming.
*Human activities have led to large increases in heat-trapping gases over the past century. The global warming of the past 50 years is due primarily to this human-induced increase. Global average temperature and sea level have increased, and precipitation patterns have changed.
*Many types of extreme weather events, such as heat waves and regional droughts, have become more frequent and intense during the past 40 to 50 years. The destructive energy of Atlantic hurricanes has increased... In the eastern Pacific, the strongest hurricanes have become stronger since the 1980s, even while the total number of storms has decreased.
*Sea level has risen along most of the U.S. coast over the last 50 years, and will rise more in the future. Arctic sea ice is declining rapidly and this is very likely to continue. Global temperatures are projected to continue to rise over this century.
*As global warming marches on and its effects unfold, the shrinkage of the Arctic ice cover that has been observed by the beginning of the 21st century may possibly be called a “poster case” for global warming.
*In the past few decades the Arctic average temperature increased at twice the rate as the rest of the world.
*Declining snow cover; widespread melting of glaciers and sea ice.
*Removal of the highly reflective Arctic ice cover reduces the albedo of the Earth – the ability of the planet to reflect a certain quantity of solar energy back to space. This leads to the Earth absorbing more sunlight and further contributes to climate warming.
*Reduction in sea ice will have a devastating effect on polar bears, ice-dependent seals and local people who use these animals as a food source
*Global warming is expected to increase forest fires and destruction of trees by insects. This will lead to the loss of valuable biodiversity-rich old-growth forests.
*Many coastal communities face exposure to storms because rising sea level and a
reduction in sea ice will allow high waves and storm surges to reach the shore; these storms in their turn will lead to coastal erosion.