Climate Change and Global Warming
Climate change refers to the variation in the Earth's global climate or in regional climates over time. These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) or, more recently, human activities.

Climate change is a broad term that can include global cooling as well as global warming. However, the terms climate change and global warming have frequently been used synonymously. Scientists tend to use the term climate change in the wider sense to also include natural changes in climate.

In terms of popular usage, global warming often refers to temperature increases which are primarily caused by human action.

Greenhouse Gases
Greenhouse gases are components of the atmosphere that contribute to the greenhouse effect. These gases can come from natural sources or from human activity. In the order of relative abundance, Earth's atmospheric greenhouse gases include:

water vapor
carbon dioxide
methane
nitrous oxide
ozone

What is the Greenhouse Effect?
The greenhouse effect is the process in which the emission of infrared radiation by the atmosphere warms a planet's surface. The Earth's average surface temperature of 15 °C (288 K) is about 33 °C warmer than it would be without the greenhouse effect.

The greenhouse effect was discovered by Joseph Fourier in 1824 and first investigated quantitatively by Svante Arrhenius in 1896. Global warming, a recent warming of the Earth, is believed to be the result of increased concentrations of greenhouse gases in the atmosphere. In addition to the Earth, Mars and Venus have greenhouse effects.

What causes Global Warming?
Global warming occurs when carbon dioxide and other gases enter Earth's atmosphere, trapping heat and light from the sun. This insulating effect leads to increased temperatures. Coal-burning power plants are the largest U.S. source of carbon dioxide pollution, producing 2.5 billion tons every year. Automobiles, the second largest source, create nearly 1.5 billion tons of CO2 annually.

Various technologies exist today to reduce the effects of global warming. The challenge is to be sure these solutions are put to use.

Global Warming versus Ozone Depletion
Global warming and ozone depletion are two different problems.

Global warming comes from release of certain gases which enhance the natural greenhouse effect. These gases trap solar heat much as a greenhouse or blanket would, and cause temperature of the lower atmosphere to rise.

The ozone layer in the lower stratosphere protects Earth by shielding it from the sun’s ultraviolet radiation. Halocarbons, which contain chlorine, fluorine, and bromine, act as catalysts to kick off a chain reaction that destroys ozone. A thinning ozone layer means more ultraviolet radiation, which can harm living things (for example, by causing skin cancer in humans).

Though different processes, global warming and ozone depletion are related in some ways. The halocarbons which destroy the ozone layer are also potent greenhouse gases.

What is Sustainability?
Sustainability can be defined as "meeting the needs of the present without compromising the ability of future generations to meet their own needs." In 1971, Herman E. Daly from the University of Maryland School of Public Policy presented three operational rules defining the condition of sustainability. They are:

Renewable resources such as fish, soil, and groundwater must be used no faster than the rate at which they regenerate.
Nonrenewable resources such as minerals and fossil fuels must be used no faster than renewable substitutes for them can be put into place.
Pollution and wastes must be emitted no faster than natural systems can absorb them, recycle them, or render them harmless.

The Carbon Footprint
A carbon footprint measures the impact human activities have on the environment in terms of the amount of greenhouse gases produced, measured in units of carbon dioxide. The carbon footprint is similar to a greenhouse gas emissions inventory. However, the carbon footprint measures emissions over the lifetime of an entity, whereas the emissions inventory is measured at increments (usually on an annual basis). The carbon footprint is calculated using the Life Cycle Assessment (LCA) method (EPA). This established method has been standardized under ISO 14044.

The carbon footprint can be efficiently and effectively reduced by applying the following steps:

Perform a Life Cycle Assessment to accurately determine the current carbon footprint.
Identify hot spots in terms of energy consumption and associated CO2-emissions.
Optimize energy efficiency to reduce greenhouse gas emissions
Identify solutions to neutralize the greenhouse gas emissions that cannot be eliminated by energy-saving measures. This may involve carbon offsetting.

Carbon Offsetting and Emissions Trading
Carbon offsetting is the act of mitigating greenhouse gas emissions - for example, planting trees to compensate for the greenhouse gases emitted from personal air travel.

The idea of paying for emission reductions elsewhere instead of reducing one's own emissions is closely related to the concept of emissions trading. With emissions trading, a central authority (government agency) sets a limit or cap on the amount of a pollutant that can be emitted. Companies are required to hold an equivalent number of credits or allowances which represent the right to emit a specific amount. The total amount of credits cannot exceed the cap, limiting total emissions to that level. Companies that need to increase their emissions must buy credits from those who pollute less. The transfer of allowances is referred to as a trade. Basically, the buyer is being fined for polluting, while the seller is being rewarded for having reduced emissions.

In contrast to emissions trading, carbon offsets generally refer to voluntary acts by individuals or companies that are arranged by commercial or not-for-profit carbon-offset providers. The most popular offset methods include:

Use of renewable energy - taking advantage of wind power, solar power, hydroelectric power, and bio-fuels
Funding energy conservation - investing in cogeneration power plants, fuel-efficiency projects, energy-efficient buildings, subsidizing public transportation
Methane capture - combusting or containing methane generated by farm animals, landfills, or other industrial waste.
Tree planting - reforestation, afforestation, and avoiding deforestation.

Controversies exist regarding the practice of carbon offsetting. Critics disagree with the practice because it does not encourage conservation, since net power consumption is not reduced. Others argue that there is lack of transparency in the industry, and that it is almost impossible to monitor the process. A major concern with carbon offsets is that unethical companies do exist, and if you are dealing with one without knowing it, you may actually be paying for nothing.

The general consensus is that an entity should reduce its own emissions as much as possible before resorting to carbon offsets.

How is Energy Measured?
The most common unit of energy in the United States is the kilowatt hour (kWh). The joule (J) is the international standard unit of energy measurement.

Whereas the kilo-watt hour is most commonly used to measure electricity used in homes and businesses, the joule is standardized by the International System of Units (SI). It is more commonly used by scientists and engineers. In the US, an electric bill for a typical homeowner would be displayed in kWh units. One kilowatt-hour is equal to 3,600,000 joules or 3.6 megajoules.

recycle

USM News:

USM goes green: Chancellor launches system-wide sustainability initiative.

"This initiative ... will make the university system a national leader in institutional responses to climate change".

View news release

Did you know?

In 2006, the United States and China were the World's Largest Polluters.

In 2006, CO2 emissions for the US were 21.44 percent of total world emissions, while China's emissions were 19.4 percent.

2006 CO2 Fact Sheet

Some reports state that due to rapid growth, China has recently surpassed the US in CO2 emissions.

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