Thursday, June 10, 2010
The greenhouse effect is the process where short wavelength radiations(Ultra Violet Radiations) from the sun reach the earth’s surface and gets converted to long wavelength radiations(heat energy). Most of the sunlight is absorbed by earth and water bodies and then re-emitted as thermal energy. As the amount of carbon in atmosphere increases the amount of heat they trap and send back to the surface increases. This effect steadily increases the temperature of earth and causes global warming.
Carbon dioxide has major stake in greenhouse gasses and most of the carbon dioxide is generated from burning fossil fuels for reasons like power generation, transportation etc,. Every year over 26 billion tons of carbon dioxide is generated and rising. There was a steady increase in CO2 since 2000 and as the economy grows the emissions also grew. Over the past hundred years, earth has warmed 0.6 degrees celcius as a result of increasing greenhouse gasses. The average surface temperatures may increase from 1.4 to 5.8°C from 1900 to 2100. Burning fossil fuels accelerates the levels of greenhouse gasses at a life-threatening rate causing global warming.
The raise in global temperatures result in melting polar ice caps, thereby increase in sea levels. This temperature raise impacts the rainfall where some areas experience heavy rainfall and less rain fall in others. Raise in sea levels is a threat to coastal and low lying areas. Flooding, extreme heat waves are some of the examples of global warming. Andhra Pradesh a state in India has experienced an extreme heat wave in the month of may 2002, when the temperature rose to 49oCelsius resulting in highest death toll in a week. This was a result of long term warming trend observed in Asia. Buenos Aires, Argentina received heaviest rains in hundred years in May 2000. It received 34.2 cm (13.5 inches) of rain in just five days; this is four times the average rainfall.
Glaciers in Himalayan mountain ranges are retreating at an average rate of 15 m per year with consistent warming recorded at Himalayan climate stations. (Kulkarini et al., 2007)
These are some of the effects of global warming. Moderate global warming would enhance the agricultural productivity across some parts of the world. Sophisticated climate models predict that the warming effect would be more at northern latitudes which means Russia and Canada could become most productive when the earth surface warms up. Rising sea levels are most disturbing, observations found that the mean sea level rise of at least one foot corresponding to an increase in approximately 10 F mean global temperature. Since the beginning of industrial revolution the concentrations of CO2 have increased by 30% and are increasing rapidly today. We also know that once the CO2 is mixed in our atmosphere and may remain until a century unless we actively participate in removing it. In order to stabilize the co2 concentrations we need to reduce the emissions well below the current rates.
There are other greenhouse gasses like methane (ch4), nitrous oxides whose contributions towards warming are also increasing. These gasses are well mixed in earth’s atmosphere and may remain there for decades. Aerosols also contribute for global warming. Volcanic eruptions eject large amounts of SO2 gasses into atmosphere. When these gasses are washed away by rainfall these gasses disperse across the world and cut’s down some of the sun’s radiations resulting in cooling the lower atmosphere. Unusual weather patterns have been observed during 1991-1992 due to volcanic dust resulting in unusual cold winters in Middle East and mild winters in Western Europe.
It’s our responsibility to make sure that our future generations would not have to face worst effects this catastrophe. Unfortunately at this point of time we do not have scientific capabilities which can remove the excess concentrations of carbon from the atmosphere; however we have the option of restricting the levels of carbon emission in to the atmosphere.
Governments of developing countries have taken steps to reduce the carbon emissions. The government of United Kingdom have implemented carbon budgets and launched a new action plan on international climate change action plan “Beyond Copenhagen; The UK Government's International Climate Change Action Plan". Post Copenhagen conference climate change has moved to political center stage for first time in many countries across the world. Leaders from 49 countries have agreed to limit the global temperature rise to 2oc and have committed to support developing countries to take action.
As per Lord Stern, if we do not take early action the long term costs of climate change with outweigh the costs of early movement to low carbon economy. In this process country showing leadership would have the advantage of new markets for low carbon goods and services. UK promises to deliver at least 34% cut in carbon emissions by 2020 and 80% by the end of 2050. UK’s contribution of £1.5billion for 2010-2012 is to take immediate action in developing countries. There has to be a significant progress to the UN framework convention for climate change negotiations towards legally binding agreement which is built on Kyoto protocol. Developed countries like Japan, Norway and Australia have increased their proposed emission reduction targets. Majority of developing countries for the first time came forward with commitments to reduce the emissions. Countries with major emerging economies like China and India have recognized that the average global temperature rise should not exceed 2oC. This is a positive leap taken by many countries to limit the carbon emissions and reduce the impacts of global warming.
In order to tackle this situation not just government’s role would be sufficient, governments have to stress more on educating its citizens to conserve energy and reduce the household carbon emissions. Emphasis on usage of renewable energy sources like solar energy, saving water, insulating their home, limited usage of household appliances and turning them off when they are not in use. These can help reduce the household carbon foot print and when everyone follows these simple guidelines a difference would be seen.
Saturday, February 3, 2007
Global warming is here, it's human-caused, and it will continue for centuries even if greenhouse-gas emissions are stabilized, an international panel of climate experts said in a report issued today.
The Intergovernmental Panel on Climate Change (IPCC) used its strongest language yet to link human activity to Earth's warming temperatures, rising seas, more intense storms, and a host of other environmental maladies.
"Fossil fuel use, agriculture, and land-use change are fundamentally affecting the systems on our planet," Achim Steiner, executive director of the United Nations Environment Programme, said at a press briefing in Paris, France.
(Get the basics: "Global Warming Fast Facts.")
The United Nations and the World Meteorological Organization oversee the IPCC.
Hundreds of climate experts and government representatives from 113 countries labored all week in Paris to reach unanimous agreement on the wording of each sentence in the 20-page summary for policymakers.
"Most of the observed increase in globally averaged temperature since the mid-20th century is very likely due to the observed increase in anthropogenic [human-caused] greenhouse gas concentrations," the report reads.
"Very Likely" a Big Step
The phrase "very likely" translates to a 90 percent probability, the report's authors note. This is a significant departure from previous reports.
In 2001 the panel concluded humans were "likely," or with 66 percent probability, the cause of global warming. The panel also released reports in 1995 and 1990.
"Each time they've used a more explicit statement about the human contribution," said Henry Jacoby, co-director of the Center for Energy and Environmental Policy Research at the Massachusetts Institute of Technology, in a phone interview Thursday.
Jacoby, who studies the threat of global climate change, said the report will cause some people to "be somewhat more concerned" but doubted it would be "revolutionary" in spurring action to reduce greenhouse gas emissions.
The report assesses the research of hundreds of climate scientists from more than 130 countries. It summarizes the current state of climate science including causes, observed changes, and projections for the future.
The full report will be released later this year. In coming months, the panel will also release chapters on global warming's threats and how to combat climate change.
Rajendra Pachauri, the IPCC chair, said at the briefing that the report's broad participation gives it "the stamp of acceptance of all the governments of the world … that really provides the credibility of this massive scientific undertaking."
Among the findings in the summary report:
• Global temperatures will increase between 2 and 11.5 degrees Fahrenheit (1.1 and 6.4 degrees Celsius) by the end of this century over pre-industrial levels.
• A best-guess temperature rise is between 3.2 and 7.1 degrees Fahrenheit (1.8 and 4 degrees Celsius), though the high end remains possible.
• Sea levels are projected to rise between 7 and 23 inches (18 and 59 centimeters) by the end of the century.
• If recent melting in Greenland and Antarctica continues, sea levels could rise an additional 4 to 8 inches (10 to 20 centimeters).
• Temperatures and sea levels will continue to rise for centuries even if greenhouse gas emissions are stabilized today.
• Eleven of the last 12 years rank among the 12 warmest years in the instrumental record, which stretches back to 1850.
• Observational evidence suggests an increase in hurricane strength in the North Atlantic since 1970 that correlates with an increase in sea surface temperatures.
• In some projections, Arctic sea ice will disappear in the late summer by the later part of this century.
• It is very likely that hot extremes, heat waves, and heavy rains will continue to become more frequent.
• The Gulf Stream, which brings warm waters to the North Atlantic, may slow but is unlikely to shut down as depicted in the Hollywood disaster movie The Day After Tomorrow.
(See National Geographic magazine's "Global Warning: Signs From Earth.")
What to Do?
MIT's Jacoby said today's report demonstrates the reality of global climate change but does "not have any very great guidance on what will be the right thing to do."
Susan Solomon, a U.S. government scientist and co-chair of the group that produced the IPCC report, noted at the briefing that deciding what to do is a job for societies, not scientists.
"In my view, that is what IPCC also is all about, namely not trying to make policy-prescriptive statements but policy-relevant statements," she said.
Daniel Sarewitz is the director of Consortium for Science, Policy and Outcomes at Arizona State University. He said the proper reaction to the IPCC report requires looking at climate change in the context of global environmental change.
For example, he said, rapid population growth along the coasts is the greatest cause of losses from hurricanes over the past century, not warming.
Fixing the problem, therefore, requires better coastal management in addition to reducing greenhouse gases.
"The major flaw of the IPCC is that it reinforces the tendency to view climate impacts in such narrow terms," he said by email on Thursday.
Pachauri, the IPCC chair, said he is hopeful that society will use the information in the report to make decisions that "reduce the risks and dangers that might exist in the future."