Everything on Earth is connected, and global climate change illustrates this concept. Global climate change is a complex issue that involves changes in the energy balance of the Earth as a result of human activities. Choices we make about the types of vehicles we drive, how we maintain our yards, what we buy, what we throw away, how we use energy resources, and what is in our homes all influence our impact on global climate change.

The terms greenhouse effect, global warming, and global climate change are sometimes used interchangeably. However, they are not the same thing. The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere trap energy from the sun. Without these gases, heat would escape back into space and Earth’s average temperature would be about 60ºF colder. Because of how they warm our world, these gases are referred to as greenhouse gases. Problems may arise when the atmospheric concentration of greenhouse gases increases.

Some greenhouse gases occur naturally in the atmosphere, while others result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases. It is the addition of greenhouse gases from these human activities that cause the greatest concern:

• Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned.

• Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills and from the raising of livestock. A recent study found that sulfur in acid rain may limit global warming by counteracting the natural production of methane gases by microbes in wetland areas.

• Nitrous oxide is emitted during agricultural and industrial activities, as well as during the combustion of solid waste and fossil fuels.

• Very powerful greenhouse gases that are not naturally occurring include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6), which are generated in a variety of industrial processes. 

Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the Earth’s atmosphere.

Each greenhouse gas differs in its ability to absorb heat in the atmosphere. Methane traps over 21 times more heat per molecule than carbon dioxide, and nitrous oxide absorbs 270 times more heat per molecule than carbon dioxide.

Fossil fuels burned to run cars and trucks, heat homes and businesses, and power factories are responsible for about 98% of U.S. carbon dioxide emissions, 24% of methane emissions, and 18% of nitrous oxide emissions. Increased agriculture, deforestation, landfills, industrial production, and mining also contribute a significant share of emissions.

Often, estimates of greenhouse gas emissions are presented in units of millions of metric tons of carbon equivalents (MMTCE), which weights each gas by its GWP value, or Global Warming Potential. Global warming refers to an average increase in the Earth’s temperature, which in turn causes changes in climate. A warmer Earth may lead to changes in rainfall patterns, a rise in sea level, and a wide range of impacts on plants, wildlife, and humans. 

When scientists talk about the issue of climate change, one of their concerns is about rapid global warming caused by human activities. Global warming is a symptom of climate change, which is a disturbance of the global energy balance. Climate is the average weather (usually taken over a 30- year time period) for a particular region and time period. Climate change represents a change in long-term weather patterns; for example, temperatures can become warmer or colder or annual amounts of rainfall or snowfall can increase or decrease. The average annual temperature experienced by a particular location is a function of latitude, cloud cover, proximity to large bodies of water, and altitude.

Scientists know for certain that human activities are changing the composition of Earth’s atmosphere. Increasing levels of greenhouse gases, like carbon dioxide (CO2), in the atmosphere since preindustrial times have been well documented. Widely recognized as the “Keeling curve,” atmospheric CO2 concentration measurements at the Mauna Loa Observatory in Hawaii, taken since 1958, constitute the longest, continuous record of atmospheric CO2 concentrations available in the world. Ice cores and tree rings also provide evidence for climate change.

It is well accepted by scientists that greenhouse gases trap heat in the Earth’s atmosphere and tend to warm the planet. By increasing the levels of greenhouse gases in the atmosphere, human activities are strengthening Earth’s natural greenhouse effect. The key greenhouse gases emitted by human activities remain in the atmosphere for periods ranging from decades to centuries. The carbon cycle is impacted by these activities. For instance, burning of fossil fuels and biomass produces carbon dioxide, and deforestation decreases carbon uptake.

Climate models predict that the global temperature will rise by about 1.4 – 5.8°C by the year 2100. This change would be much larger than any climate change experienced over at least the last 10,000 years. The projection is based on a wide range of assumptions about the main forces driving future emissions (such as population growth and technological change). It is based on current emissions trends and assumes that no efforts are made to limit greenhouse gas emissions.

Emissions of GHGs vary based on the country in which you live. The United States presently emits more greenhouse gases per person than any other country, and we have the greatest emissions per capita. In the United States, approximately 6.6 tons (almost 15,000 pounds carbon equivalent) of greenhouse gases are emitted per person every year. Emissions per person increased about 3.4% between 1990 and 1997.

Emissions also vary based on the state in which you live. Several factors can affect the emissions per person in a state, including the types of fuel used to generate electricity, population size, vehicle miles traveled (people tend to drive longer distances in sparsely populated areas), and whether fossil fuels are extracted or processed within the state. According to the Michigan Greenhouse Gas Inventory, Michigan greenhouse gas emissions per capita increased from 6.17 metric tons carbon equivalent (MTCE) in 1990 to 6.23 MTCE in 2002. Michigan greenhouse gas emissions accounted for 3.3 percent of total U.S. greenhouse gas emissions in 2002 and 3.4 percent of total U.S. greenhouse gas emissions in 1990.

About 85% of these emissions are carbon dioxide from burning fossil fuels to generate electricity and power our vehicles. The remaining emissions are largely methane (9%) from the decomposition of wastes in landfills, ruminant digestion and manure management associated with domestic livestock, natural gas and oil systems, and wastewater treatment. Another contribution is nitrous oxide (4%) from agricultural soil management and mobile sources.

Five sources and sinks were evaluated for Michigan’s inventory: energy, industrial processes, agriculture, land use change, and waste. The largest contributor to total emissions in Michigan is the electricity generation sector (33% of total emissions in 2002). The second largest contributor is the transportation sector (26%). In 2002, industry contributed 17% to total emissions. Contributions from other sectors were residential (11%), commercial (10%), and agriculture (3%).

There is an important link between GHGs and solid waste. The disposal of solid waste produces GHGs in a number of ways. First, the anaerobic decomposition of waste in landfills produces methane. Second, the incineration of waste produces carbon dioxide as a by-product. In addition, the transportation of waste to disposal sites produces GHGs from the combustion of the fuel used in the equipment. Finally, the disposal of materials indicates that new products are being produced as replacements; this production often requires the use of fossil fuels to obtain raw materials and manufacture the items.

With increased emissions of greenhouse gases leading to global warming, changes to Earth systems and ecosystems are becoming apparent. Effects of global climate change vary with location and the type of ecosystem. For example, there appears to be an increase in frequency of extreme weather-related events, Arctic sea ice is melting, tropical diseases are spreading their range, geographic ranges of plants and animals are changing, glaciers are disappearing, and sea levels are rising.

Global cooperation coupled with individual actions is needed to address climate change. Recognizing the problem of global climate change, the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988. The role of the IPCC is to assess on a comprehensive, objective, open and transparent basis the scientific, technical, and socioeconomic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts, and options for adaptation and mitigation.

The Kyoto Protocol is a pact agreed on by governments at a United Nations conference in Kyoto, Japan, in 1997. Its purpose was to reduce the amount of greenhouse gases emitted by developed countries by 5.2 percent of 1990 levels during the five-year period 2008-2012. The Kyoto Protocol became effective on February 16, 2005. The United States had not ratified the Protocol when it came into effect. The Federal government is using voluntary and incentive-based programs to reduce emissions and has established programs to promote climate technology and science. Also, states have formulated climate change action plans.

These plans help states identify and evaluate feasible and effective policies to reduce their greenhouse gas (GHG) emissions through a combination of public- and private-sector policies and programs. By taking a proactive approach to planning GHG emissions reductions, states can lower their GHG emissions, reduce their energy costs, protect air quality and public health, and improve the economy and environment.

State agencies and/or other members of a task force develop a GHG inventory and make projections of GHG emission levels for their state. They identify areas where reductions would be feasible and, in some cases, they develop a voluntary GHG emission reduction goal. Collectively, they identify and select policy options based on several characteristics, including GHG reduction potential, cost-effectiveness, ancillary benefits, political feasibility, and public acceptance. Policies are ultimately ranked and selected by the task force. The best policy mix to achieve the plan’s objectives are specified in the state action plan as recommendations and shared with state policymakers. Often the plan is circulated to the public for comments during the process.

Michigan’s greenhouse gas inventory has been completed, and an action plan was formulated in 2009. Companies and electric utilities in Michigan have voluntarily responded to the issue. For example, the U.S. EPA, DaimlerChrysler, and the United Parcel Service (UPS) are collaborating to put several zero-emission package delivery vehicles powered by hydrogen fuel cells into commercial service in Michigan. This joint initiative marks the first time that efficient, zero emission fuel cell delivery vehicles have been introduced as a part of a commercial vehicle fleet in North America. General Motors’ U.S. facilities reduced their overall composite greenhouse gas (GHG) emissions more than 72 percent in the period between 1990 and 2003; the company also began a tree-planting program in 1990 that has put more than one million trees in the ground. Ford Motor Company is a founding member and the only auto manufacturer participating in the U.K. Trading Scheme and the Chicago Climate Exchange, two innovative and market-based trading programs with voluntary greenhouse gas emissions reduction targets. Since 1996, DTE Energy has achieved a steady decline in CO2 emissions per megawatt-hour (MWh) for both fossil fuel generation and total system generation. Consumers Energy manages its business with an eye on understanding the environmental aspects of its activities.

As an individual, you can affect the emissions of about 4,800 pounds of carbon equivalent, or nearly 32% of the total emissions per person, by the choices you make in three areas of your life. These areas are the electricity you use in your home, the waste you produce, and your choice of personal transportation. The other 68% of emissions are affected more by the types of industries in the Michigan, efficiency of energy use in buildings, how our food is grown, and other factors.