Climate Change and Global Warming | Blog Action Day
Thursday, October 15, 2009
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The whole world is facing the challenge of climate change, and it is not only an environmental issue. It is a complex issue of sustainable development, which arises mainly due to unsustainable energy production and consumption.
Solutions to address climate change issues can serve as a tool for addressing many other sustainable development concerns. One of the key sectors in terms of mitigation is the energy supply sector. More than two thirds of global greenhouse gas emissions come from this sector and the way in which future energy needs are met will determine whether the efforts to address climate change will remain manageable.
What is climate change and why should we be concerned about it?
What is climate change?
The Earth's climate has always varied, so the term climate change is now generally used to describe the changes caused by human activity - specifically, greenhouse emissions such as carbon dioxide and methane, which build up in the atmosphere and trap heat.
Is it the same as global warming?
As human activity increases the concentration of these gases in the atmosphere far beyond their natural levels, much more heat is trapped. Hence, the term climate change is often used interchangeably with global warming.
Can it be explained by natural causes?
Measurements at the Earth's surface show that average temperatures have risen by some 0.4C since the 1970s. Scientists are confident this change can be blamed on human emissions because the increase is too big to be explained by natural causes.
Although natural factors such as changes in the sun and large volcanic eruptions are known to have warmed and cooled the planet in the past, these effects are not powerful enough to explain the rapid warming seen recently. Only an increased greenhouse effect caused by higher amounts of heat-trapping gases in the atmosphere can explain it.
What is the main greenhouse gas?
Water vapour in the atmosphere produces the strongest greenhouse effect, but it has been in balance for millions of years. Human emissions, though relatively small, tip that balance.
Carbon dioxide is the chief greenhouse gas produced by human activity. It is produced when we burn fossil fuels: oil, gas and coal. The level of carbon dioxide in the atmosphere is measured in parts per million (ppm).
Before the industrial revolution, the carbon dioxide level was about 280ppm. It is now 386ppm and rising by 2-3ppm each year. When other greenhouse gases such as methane are included, the total level in the atmosphere, known as the carbon dioxide equivalent, is closer to 440ppm.
What future temperature rise is expected?
Scientists say continued emissions will cause the planet to heat up further. To work out how much, they use computer models based on the programs used to predict the weather.
These models are not perfect, and struggle to simulate some features of the climate system such as clouds. To get around this, the scientists run many different versions and pool the results. The computer models predict that if emissions continue to rise at the present rate, average temperatures will most likely increase by 4C by 2100.
There are uncertainties, though - for example, the planet's oceans, forests and soils could release their massive stocks of carbon as the world warms, leading to much greater temperature rises than human emissions alone would cause.
Why are warmer temperatures bad?
Most plants and animals have evolved to live in a fairly narrow ecological niche. Some will move to find their desired conditions, others will be able to adapt. Those that cannot move or adapt will perish. Some animals, such as the polar bear, have nowhere to move to.
A warmer climate will affect agriculture and water availability. Increased temperatures are also expected to limit rainfall in some regions and bring more extreme weather events such as storms to others.
Sea levels will rise - gradually at first as the extra warmth works its way into the oceans and makes them expand; more quickly if the gigantic ice sheets in Greenland and west Antarctica start to break up.
How can we tackle global warming?
Scientists say the only realistic way at present is to reduce greenhouse gas emissions. How to do that - and where - is a political hot potato.
Because it takes time for the heat to build up in the atmosphere, and because carbon dioxide stays in the atmosphere for a long time, there is a lag in the system, which means the effect of any changes will not be felt for decades. Put bluntly, we are headed for about another 0.5C of warming whatever we do.
What are the Kyoto protocol and the Copenhagen climate talks?
The world's only existing treaty to limit emissions, the Kyoto protocol, has had limited success, and expires in 2012. Politicians are working to develop a replacement that would include countries excluded from Kyoto, such as China, and those that refused to join, such as the US.
From December 7, environment ministers and officials will meet in Copenhagen to thrash out a successor to Kyoto. The two week event is being seen by many environmentalists as a crucial diplomatic opportunity to create an international agreement on meaningful cuts in emissions that will prevent the worst consequences of climate change.
Can renewable energy help?
The United Nations Intergovernmental Panel on Climate Change has said that we already have most of the technology we need to bring down emissions significantly. These include renewable energy sources such as windmills, geothermal and solar panels, as well as more efficient cars and power stations.
What about storing the CO2 underground or blocking the sun?
One technology that would allow us to continue burning fossil fuels such as coal and oil without increasing CO2 levels in the atmosphere is carbon capture and storage (CCS). This involves extracting CO2 at power stations then pumping it underground. Critics argue the technology will prove expensive and is several years away from being proven.
A more drastic approach is so-called geo-engineering. These are major technological fixes such as seeding clouds to bounce some of the sun's radiation back into space or stimulating the growth of algae in the oceans to soak up CO2
These are much more speculative, but Barack Obama's scientific adviser, John Holdren, has said that he is open to even these drastic measures.
Some explanation on Global Warming from Wikipedia
From Wikipedia,
Global warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-20th century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the last century.[1][A] The Intergovernmental Panel on Climate Change (IPCC) concludes that most of the observed temperature increase since the middle of the 20th century is caused by increasing concentrations of greenhouse gases resulting from human activity such as fossil fuel burning and deforestation.[1] The IPCC also concludes that variations in natural phenomena such as solar radiation and volcanoes produced most of the warming from pre-industrial times to 1950 and had a small cooling effect afterward.[2][3] These basic conclusions have been endorsed by more than 40 scientific societies and academies of science,[B] including all of the national academies of science of the major industrialized countries.[4] A small number of scientists dispute the consensus view.
Climate model projections summarized in the latest IPCC report indicate that the global surface temperature will probably rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the twenty-first century.[1] The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. Some other uncertainties include how warming and related changes will vary from region to region around the globe. Most studies focus on the period up to the year 2100. However, warming is expected to continue beyond 2100 even if emissions stop, because of the large heat capacity of the oceans and the long lifetime of carbon dioxide in the atmosphere.[5][6]
An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.[7] The continuing retreat of glaciers, permafrost and sea ice is expected, with warming being strongest in the Arctic. Other likely effects include increases in the intensity of extreme weather events, species extinctions, and changes in agricultural yields.
Political and public debate continues regarding climate change, and what actions (if any) to take in response. The available options are mitigation to reduce further emissions; adaptation to reduce the damage caused by warming; and, more speculatively, geoengineering to reverse global warming. Most national governments have signed and ratified the Kyoto Protocol aimed at reducing greenhouse gas emissions.
Greenhouse gases
The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in the atmosphere warm a planet's lower atmosphere and surface. It was discovered by Joseph Fourier in 1824 and was first investigated quantitatively by Svante Arrhenius in 1896.[19] Existence of the greenhouse effect as such is not disputed, even by those who do not agree that the recent temperature increase is attributable to human activity. The question is instead how the strength of the greenhouse effect changes when human activity increases the concentrations of greenhouse gases in the atmosphere.
Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F).[20][C] The major greenhouse gases are water vapor, which causes about 36–70 percent of the greenhouse effect; carbon dioxide (CO2), which causes 9–26 percent; methane (CH4), which causes 4–9 percent[not in citation given]; and ozone (O3), which causes 3–7 percent.[21][22] Clouds also affect the radiation balance, but they are composed of liquid water or ice and so are considered separately from water vapor and other gases.
Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. The concentrations of CO2 and methane have increased by 36% and 148% respectively since the mid-1700s.[23] These levels are much higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores.[24] Less direct geological evidence indicates that CO2 values this high were last seen about 20 million years ago.[25] Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, particularly deforestation.[26]
CO2 concentrations are continuing to rise due to burning of fossil fuels and land-use change. The future rate of rise will depend on uncertain economic, sociological, technological, and natural developments. Accordingly, the IPCC Special Report on Emissions Scenarios gives a wide range of future CO2 scenarios, ranging from 541 to 970 ppm by the year 2100.[27] Fossil fuel reserves are sufficient to reach these levels and continue emissions past 2100 if coal, tar sands or methane clathrates are extensively exploited.[28]
The destruction of stratospheric ozone by chlorofluorocarbons is sometimes mentioned in relation to global warming. Although there are a few areas of linkage, the relationship between the two is not strong. Reduction of stratospheric ozone has a cooling influence, but substantial ozone depletion did not occur until the late 1970s.[29] Tropospheric ozone contributes to surface warming.[30]
More information concerning Global Warming at WIKIPEDIA.
My post is dedicated to " Blog Action Day " ( 15/10/2009 ) concerning climate change around the world.
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