Tuesday, November 27, 2007

Summary of Climate change

Book review from Benjamin

“Climate Change is an issue of intergenerational justice. If we know how our actions affect our planet, it would be criminal to keep acting like we are now, knowing that it jeopardizes future generations.”Greenhouse gases’ is the main contributor to climate change. This is because the earth’satmosphere acts much like a giant greenhouse. The gases allow solar radiation (heat) to pass through the atmosphere but, after it is absorbed and re-radiated by the earth, the gases prevent this heat from escaping back into space. Under natural circumstances this is what keeps the earth warm enough to support life. But current conditions are far from natural. Since the beginning of the Industrial Revolution, when humans began burning fossil fuels on an unprecedented scale, greenhouse gases have steadily been piling up in the atmosphere. Many of these gases last far longer than a century. As a result, current carbon dioxide (CO2)concentrations are now 35.4% higher than pre-industrial levels and growing rapidly. They are now far above any level in the past 650,000 years. Likewise, methane (CH4) concentrations have more than doubled to far above anything seen in the past 650,000 years. Global emissions of all greenhouse gases have increased by 70% between 1970 and 2004. The consequence of all this is that more and more heat is being trapped in our atmosphere, leading to an ‘enhancedgreenhouse effect.’

The world is warming incredibly fast. Global temperatures have risen by 0.76˚C since 1850, with the rate of warming for the past 50 years double that for the past century. Eleven ofthe past twelve years rank among the twelve warmest years since records began in 1850.

There are many different greenhouse gases responsible for climate change, but just three – CO2 (carbon dioxide), CH4 (methane) and N2O (nitrous oxide) – account for almost 99% of the total.Nitrous Oxide – N2O• Nitrous oxide is 275 times more potent than CO2 Sources:• Agriculture and land-use change – Natural emissions from the soil are greatly increased with the application of fertilisers and other materials, which are commonly used today in intensive agriculture. Deforested and degraded land also releases higher emissions• Combustion of fossil fuels, in cars as well as in industrial processes. Hydrofl uorocarbons, perfl uorocarbons, sulphur hexafl uoride – HFC, PFC, SF6 These three gases are extremely powerful and often have very long lifespans. Sulphur hexafl uoride, for example, is over 22,000 timesmore potent than CO2 and lasts for 3200 years!! Fortunately, these gases are emitted in very small quantities that are generally easy to reduce. Their main sources include semi-conductor manufacturing, the production of aluminium (PFCs) and magnesium (SF6), electricaltransmission (SF6), and the replacement of ozone-depleting substances with HFCs.Carbon Dioxide – CO2• By far the most prevalent greenhouse gas, currently accounting for about 77% of total concentrations. Since it is so common, CO2 (or simply “carbon”) is often used as shorthand for all greenhouse gases.

Sources:• Burning of fossil fuels such as coal, oil and gas (eg. for electricity generation and transportation)•

Land-use change: Through photosynthesis, plants absorb CO2, thereby acting as a ‘sink’ and balancing emissions. When forests are destroyed and supplanted by other land uses, such as farms or cities, these important sinks are removed, leading to a net increase in emissions.

Current concentrations of CO2 are at 379 ppm (IPCC, 2007), while total concentrations of all greenhouse gases are at 430ppm CO2e.

Methane – CH4• Though shorter lived, it is 62 times more powerful as a greenhouse gas than CO2Sources:• Agriculture, especially livestock – high emissions from cattle/ sheep. In some livestock-intensive countries, such as New Zealand, methane is often the number one greenhouse gas.• The retrieval, processing and distribution of fossil fuels - coal mining and the use of natural gas account for the second-largest portion of methane emissions• Waste – methane is emitted as a ‘landfill gas’ from decomposing waste in anaerobic (oxygen-free) conditions.

What we can do to reducing emissions:

1. Power Stations- Use less power (and save money) by increasing energy efficiency in your home and workplace- Switch from dirty power to clean, renewable energy like wind and solar, regulate emissions, research new technologies like carbon capture and storage (CCS).

2. Waste Disposal and Treatment- Reduce your waste, re-use, recycle and compost!- Better waste diversion, landfi ll gas recovery, packaging directives Land Use and Biomass Burning- Avoid unsustainably-harvested wood products and paper with a low recycled content- Provide clean energy alternatives to biomass burning, provide incentives for forest conservation Residential, Commercial, and Other Sources- Improve energy effi ciency of buildings by improving insulation, favouring natural light and air circulation, moreeffi cient lighting, appliances, etc.- Introduce greener building standards, better town planning Fossil Fuel Retrieval, Processing, and Distribution- Use fewer fossil fuels by driving less, switching to renewable energy- Regulation and emissions limits for extraction, refi ning and distribution processes, implementation of new technologies Agricutural Byproducts- Support organic agriculture, eat less meat- Regulate intensive agriculture, promote alternatives and lowerimpact farming Transportation Fuels- Drive less by using alternative forms of transport, eat local- Improve vehicle efficiency standards, promote lower-emission technologies.

3. Industrial Processes- Consume less, consume wisely (choose products manufactured in an environmentally-friendlyway)- Government regulation of industrial emissions.