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Climate Change, CO2 and Carbon
[top] [end]1. Issue in brief[top] [end]Global warming and climate changeGlobal warming has always taken place; without it, the planet would be freezing cold and uninhabitable. It is caused by sunlight, which radiates to the earth as short wave radiation, being trapped by the 'greenhouse gases' surrounding the earth. As the solar radiation reaches the earth and the atmosphere around it (the troposphere), that part of the radiation which is converted to infra-red radiation can no longer pass through these gases so freely and is locked into the atmosphere. To try to return to an equilibrium, the air heats up until the outgoing long-wave radiation (OLR) matches the incoming solar radiation. Currently, this steady state is not being reached and the planet is gradually becoming hotter - known as the Enhanced Greenhouse EffectRadiative forcing describes the changes brought about by the mechanism described above. A positive radiative forcing makes the earth and the atmosphere around it hotter (global warming), whilst a negative radiative forcing makes it cooler. [top] [end]2. Trends and History[top] [end]Greenhouse gases and aerosols[top] [end]Greenhouse gasesGreenhouse gases can be split into those that are naturally occurring, and those that are produced as a result of human activity. Important greenhouse gases include carbon dioxide, ozone, methane, nitrous oxide and water vapour. Over the last thirty or so years, there has been a steady and unprecedented climb in the levels of greenhouse gases, and most people now believe that this accelerated growth is largely man-made (anthropogenic). This increase in greenhouse gases is raising the temperature of the earth and the air around it to dangerous levels. Manufacturing, power generation, farming and transport are largely blamed, and the excessive level of greenhouse gases they produce are believed to be at the root of climate change.See a country list of Carbon Dioxide emissions per capita here [top] [end]AerosolsAerosols (microscopic airborne particles or droplets) affect global warming. Some of them (such as those from erupting volcanoes) have a cooling effect. Most aerosols will scatter and absorb solar and infrared radiation in the atmosphere, and have probably had an overall negative contribution to global warming. They also affect cloud formations by increasing the numbers of fine particles that retain the droplets in warm clouds.On the other hand, black carbon (soot), created by burning carbonaceous fuels, tend to warm the planet. The quantity of black carbon is a function of the way in which it is burnt, and recent research indicates that the smoke from household cooking stoves is particularly high in black carbon. [top] [end]Feedback effects'Positive feedbacks' involving water vapour, snow, and ice may amplify the direct response to greenhouse gas emissions by a factor of two to three. The water vapour feedback is particularly important as water vapour is a powerful greenhouse gas, and models project that global warming will raise water vapour levels in the lower atmosphere - a phenomenon that appears to be happening already, particularly in the Northern hemisphere. Water vapour concentrations are affected by temperature and pressure, which dictate how much vapour can be carried within the atmosphere. If water vapour is at an altitude where the temperature is lower than ground temperature it will inhibit outgoing radiation, causing positive forcing. As the difference in these two temperatures widens, the effect is exacerbated. Further, as the air warms, allowing more water vapour to be held, this increases the effect, and is known as positive water vapour feedback.Snow and ice reflect sunlight very effectively. If a small warming melts snow earlier in the year, more energy will be absorbed by the ground exposed underneath it, in turn causing more warming. This is the main reason wintertime northern regions are expected to warm the most. Clouds are closely connected with this system; although they may prevent infrared radiation from escaping, they also reflect back some of the solar radiation. As clouds form from water vapour, they release latent heat, which can be a central influence in a weather system (http://www.grida.no/climate/ipcc_tar/wg1/266.htm). [top] [end]3. Current Best PracticeHEDON Household Energy Network has created a special interest group called CarbonSIG where through this, people who are concerned and working on climate change issues are trying to create a sustainable environment that benefits those living in poverty through information, discussion and action around improved household energy.Authors / contributers wanted! Do you have knowledge or expertise in this topic? If you do, please consider writing something for this topic... [top] [end]4. Areas of Research[top] [end]Cooking and greenhouse gasesOver two billion people cook using biomass, and yet more cook one coal - the majority of whom cook over three-stone fires and / or rudimentary stoves. These cooking methods lead to substantial levels of Products of Incomplete Combustion (PICs) - over one hundred of them, among which are some of the more potent greenhouse gases, including methane and Nitrous oxide . The amount of global warming attributed to each gas is known as its Global Warming Potential (GWP), which describes its potential relative to carbon dioxide. As gases break down over different periods of time, GWP changes with the time period over which the global warming is being considered - known as the Time Horizon.Table 1 shows some of the more common greenhouse gases, modified from the IPCC working group report 2001, showing the GWP with a time horizon of 100years: (http://www.grida.no/climate/ipcc_tar/wg1/130.htm#tab41a)
Note, however, that black carbon does not appear in these tables despite its high global warming potential. For further information on black carbon see: [top] [end]Effects of global warmingThere is a growing consensus that, with a business-as-usual scenario, the mean global temperature will increase by between 2C and 5C before the end of this century. We are already seeing the impacts:
Just to maintain the status quo of levels of carbon dioxide and other greenhouse gases affecting our planet, we need to reduce emissions by around 70%. [top] [end]5. Organisations/People[top] [end]International actionSince 1994, most countries of the world have joined an international treaty -- the United Nations Framework Convention on Climate Change (http://unfccc.int/2860.php ) to consider what can be done to reduce global warming and to cope with whatever temperature increases are inevitable. The Convention on Climate Change sets an overall framework for intergovernmental efforts to tackle the challenge posed by climate change. Under the Convention, governments strive to:
An addition to the treaty, the Kyoto Protocol, has more powerful (and legally binding) measures. Not all countries - notably the US - have signed up to this Treaty to date. [top] [end]Who does what?Main actors at international level
Expert groups
Partner agencies include
[top] [end]6. Resources and web links[top] [end]HEDON Cooking and Carbon Special Interest GroupCarbon SIG is a special interest group on cooking and carbon being established to discuss all things dealing with all things to do with climate change and household energy. Its specifically aims are to connect people and organisations working on household energy and carbon emission reduction, sequestration and adaptation to climate change, to support high quality business, government and NGO networking, to foster co-ordination and collaboration leading to the creation of new knowledge and ultimately improved household energy provision and finally to support information exchange on carbon emission reduction, carbon sequestration, and climate adaptation in the household energy sector. Carbon SIG special interest group has its own vocabulary for making the various meanings of words for climate change and household energy precise and comprehensive to people that do not have specific knowledge on this field. You can see the CarbonSIG glossary here?[top] [end]Climate change scienceThe IPCC website on climate change (http://www.grida.no/climate/ipcc_tar/wg1/index.htm) provides a very comprehensive scientific background to the current situation. It looks at evidence based on temperature of both land and sea, humidity, clouds, rainfall, snow and ice cover - and analyses the likely effects of global warming for separate geographic areas. The summary for policymakers provides an excellent overview http://www.grida.no/climate/ipcc_tar/wg1/005.htm)[top] [end]Carbon tradingCarbon trading - or carbon emissions trading - is a concept where companies in the industrial world can agree to offset some of their emissions by paying for those emissions to be reduced in a developing country. There is substantial argument over whether these emission reductions are 'real' or whether this mechanism allows large industrial organisations to continue to pollute by giving them a 'conscience clause' in that their payment is used to fund development in other countries. Emissions are sold by price per tonne of carbon dioxide saved. There are two distinct mechanisms:
[top] [end]7. Documents and further readingThese resources have been taken from the Carbon SIG special interest group page
[top] [end]Contributors
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12 February 2007; Last edited:
02 October 2008; Version: 14 | |||||||||||||
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HEDON CarbonSIG message on Non-renewable biomass and household energy (49 KB)