Earth Forum Posts

How can I reduce my carbon footprint?

1. Save energy (and money): switch to Energy Star qualifying compact fluorescent lightbulbs; draft-proof your windows and doors; consider a ceiling fan to push warm air to the floor in winter and help circulate cool air in the summer; set your heater to 68 ºF (or lower) in the winter, and your air conditioner to 72 ºF (or higher) in the summer; wash your clothes in cold water and dry them outside in the summer; if you need a new appliance, consider purchasing Energy Star appliances.
2. Think before you drive: try walking, biking, or public transportation; cut down unnecessary car trips and combine errands; keep your car serviced regularly; keep your tires properly inflated.
3. Recycle: make an effort to always recycle your plastic, metal and glass; recycle your food waste by starting a compost pile. Remember to first reduce, then reuse, then recycle!
4. Buy recycled products: recycled products generally use less energy; look for paper with a minimum of 30% post-consumer waste, purchase goods with less packaging (i.e. less waste).
5. Choose green electricity: contact your utility company to check whether renewable energy, such as solar or wind, is available to you; if this is not an option, consider purchasing carbon offsets for your electricity use.
6. Use your consumer power: make informed choices about the products you buy; support businesses that sell climate-friendly products.

What is the greenhouse effect?

The Sun powers Earth’s climate, radiating energy at very short wavelengths, predominately in the visible or near-visible (e.g., ultraviolet) part of the spectrum. Roughly one-third of the solar energy that reaches the top of Earth’s atmosphere is reflected directly back to space. The remaining two-thirds is absorbed by the surface and, to a lesser extent, by the atmosphere. To balance the absorbed incoming energy, the Earth must, on average, radiate the same amount of energy back to space. Because the Earth is much colder than the Sun, it radiates at much longer wavelengths, primarily in the infrared part of the spectrum. Much of this thermal radiation emitted by the land and ocean is absorbed by the atmosphere, including clouds, and reradiated back to Earth. This is called the greenhouse effect. The glass walls in a greenhouse reduce airflow and increase the temperature of the air inside. Analogously, but through a different physical process, the Earth’s greenhouse effect warms the surface of the planet. Without the natural greenhouse effect, the average temperature at Earth’s surface would be below the freezing point of water. Thus, Earth’s natural greenhouse effect makes life as we know it possible. However, human activities, primarily the burning of fossil fuels and clearing of forests, have greatly intensified the natural greenhouse effect, causing global warming.

How do human activities contribute to climate change and how do they compare with natural influences?

Human activities contribute to climate change by causing changes in Earth’s atmosphere in the amounts of greenhouse gases, aerosols (small particles), and cloudiness. The largest known contribution comes from the burning of fossil fuels, which releases carbon dioxide gas to the atmosphere. Greenhouse gases and aerosols affect climate by altering incoming solar radiation and out-going infrared (thermal) radiation that are part of Earth’s energy balance. Changing the atmospheric abundance or properties of these gases and particles can lead to a warming or cooling of the climate system. Since the start of the Industrial Era (about 1750), the overall effect of human activities on climate has been a warming influence. The human impact on climate during this era greatly exceeds that due to known changes in natural processes, such as solar changes and volcanic eruptions.

Are the increases in atmospheric carbon dioxide and other greenhouse gases during the Industrial Era caused by human activities?

Yes, the increases in atmospheric carbon dioxide (CO₂) and other greenhouse gases during the Industrial Era are caused by human activities. In fact, the observed increase in atmospheric CO₂ concentrations does not reveal the full extent of human emissions in that it accounts for only 55% of the CO₂ released by human activity since 1959. The rest has been taken up by plants on land and by the oceans. In all cases, atmospheric concentrations of greenhouse gases, and their increases, are determined by the balance between sources (emissions of the gas from human activities and natural systems) and sinks (the removal of the gas from the atmosphere by conversion to a different chemical compound). Fossil fuel combustion (plus a smaller contribution from cement manufacture) is responsible for more than 75% of human-caused CO₂ emissions. Land-use change (primarily deforestation) is responsible for the remainder. For methane, another important greenhouse gas, emissions generated by human activities exceeded natural emissions over the last 25 years. For nitrous oxide, emissions generated by human activities are equal to natural emissions to the atmosphere. Most of the long-lived halogen-containing gases (such as chlorofluorocarbons) are manufactured by humans, and were not present in the atmosphere before the Industrial Era. On average, present-day tropospheric ozone has increased 38% since pre-industrial times, and the increase results from atmospheric reactions of short-lived pollutants emitted by human activity. The concentration of CO₂ is now 379 parts per million (ppm) and methane is greater than 1,774 parts per billion (ppb), both very likely much higher than any time in at least 650 kyr (during which CO₂ remained between 180 and 300 ppm and methane between 320 and 790 ppb). The recent rate of change is dramatic and unprecedented; increases in CO₂ never exceeded 30 ppm in 1 kyr – yet now CO₂ has risen by 30 ppm in just the last 17 years.

If emissions of greenhouse gases are reduced, how quickly do their concentrations in the atmosphere decrease?

The adjustment of greenhouse gas concentrations in the atmosphere to reductions in emissions depends on the chemical and physical processes that remove each gas from the atmosphere. Concentrations of some greenhouse gases decrease almost immediately in response to emission reduction, while others can actually continue to increase for centuries even with reduced emissions.

Why do some companies undertake voluntary greenhouse gas reductions?

They seek strategic advantages through (1) operational improvement; (2) anticipating and influencing regulations; (3) accessing new sources of capital; (4) improving risk management; (5) elevating corporate reputation; (6) identifying new market opportunities; and (7) enhancing human resource management. Each presents new kinds of questions to help companies ascertain their vulnerability under a climate change protocol.

What is the risk to a company that does not take action now to reduce greenhouse gas emissions?

They risk missing out on myriad of near-term financial opportunities such as lower energy costs, minimized emissions, access to new sources of capital, and improved risk management. Inaction also sets a company up for long-term political and financial challenges. Advancing climate regulation, rising energy prices, and the investment community’s increasing attention on climate change all bring a fluid business environment into stark relief. The rules of the game are changing in ways that cannot be ignored. In the near term, companies need to be prepared for a carbon-constrained world that will alter existing business models. In the long term, they need to be prepared for a carbon-constrained world in which they will be transformed.

What are Certified Emissions Reduction (CER)?

Reductions of greenhouse gases achieved by a Clean Development Mechanism (CDM) project. A CER can be sold or counted toward Annex I countries’ emissions commitments. Reductions must be additional to any that would otherwise occur.

What is the Clean Development Mechanism (CDM)?

One of the three market mechanisms established by the Kyoto Protocol. The CDM is designed to promote sustainable development in developing countries and assist Annex I Parties in meeting their greenhouse gas emissions reduction commitments. It enables industrialized countries to invest in emission reduction projects in developing countries and to receive credits for reductions achieved.

What is Emissions Trading?

A market mechanism that allows emitters (countries, companies, or facilities) to buy emissions (”permits” or “credits”) from or sell emissions to other emitters. Emissions trading is expected to bring down the costs of meeting emission targets by allowing those who can achieve reductions less expensively to sell excess reductions (e.g. reductions in excess of those required under some regulation) to those for whom achieving reductions is more costly.

How is energy connected to climate change?

The combustion of oil, coal, and natural gas is the single largest human contribution to global warming. Atmospheric releases from fossil fuel energy systems comprise 64 percent of global anthropogenic carbon dioxide emissions from 1850-1990 and 17 percent of global anthropogenic methane emissions from 1860-1994. The majority of these emissions come from energy use in power generation and transportation. Improving the efficiency of energy use and developing low-carbon energy sources is essential if we are to avoid the more serious possible impacts of future climate change.

Sources:

• Clean Air-Cool Planet
• Cleveland, Cutler (Lead Author); Peter Saundry (Topic Editor). 2008. “Energy transitions past and future.” In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth April 11, 2007; Last revised January 27, 2008; Retrieved April 18, 2008].
• Hoffman, Andrew J. (Lead Author); Michael Toffel (Topic Editor). 2007. “Business strategy and climate change.” In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth May 19, 2007; Last revised September 27, 2007; Retrieved April 18, 2008].
• IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

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