Carbon dioxide is the largest component of greenhouse gas, making up over 80 percent of total U.S. greenhouse gas emissions (EPA, 2013). The largest source of CO₂ emissions is from the burning of fossil fuels such as gasoline, natural gas and coal.

Methane makes up about 10 percent of U.S. greenhouse gas emissions. Human-generated sources of methane include: natural gas distribution, landfills and livestock handling.

About 4 percent of U.S. greenhouse gas emissions are nitrous oxide. The major N₂O sources are agricultural soil and animal management and fossil fuel combustion.

The Federal government uses voluntary, regulatory and incentive-based programs to reduce emissions and established programs to promote climate technology and science. For more information on actions the federal government is taking to reduce greenhouse gas emissions and slow climate change, visit: http://epa.gov/climatechange/initiatives/index.html.

In addition to impacting our ecosystems, climate changes can affect air quality, water availability and human health. Temperatures in the desert Southwest are expected to rise, and rainfall is expected to decrease. These changes, coupled with the urban heat island effect will greatly impact our desert cities. Both Pima County, the City of Tucson and the surrounding jurisdictions support programs to address the harmful effects of urban heat islands. There are initiatives in place that increase green space, encourage planting of native trees, and promote light-colored, permeable materials for parking lots and roads.

Hotter and drier conditions can adversely impact air quality and human health in several ways.Drier conditions can promote the suspension of more dust and particulates in the air and higher temperatures could elevate our ozone levels. Currently, ozone levels in Pima County are at 90 percent of the EPA’s health standard. At high levels, these air pollutants are lung irritants and can cause heart and lung damage.

Reductions in rainfall would decrease the volume of water draining from the landscape and entering rivers and washes, thereby reducing the water available for people’s needs. Actions such as rainwater harvesting and use of gray water can reduce the demand for our limited drinking water supply.
 

Several PAG programs work to reduce greenhouse emissions in the Tucson region.

Clean Air Starts with Me Program

PAG’s Air Quality Planning program, in cooperation with the Pima County Department of Environmental Quality, coordinates an air pollution reduction outreach campaign to educate the public on ways to reduce vehicle travel and promote vehicle maintenance to help keep our air clean.

Travel Reduction Program

PAG’s Travel Demand Management (TDM) program includes a region wide Sun Rideshare and Travel Reduction Program. TDM promotes the use of alternative transportation modes for the daily work trip to reduce air and stormwater pollution, energy consumption and traffic congestion in the region.

Clean Cities Alternate Fuels Program

PAG manages the Clean Cities Program, a voluntary initiative of the U.S. Department of Energy. The program promotes the expansion of cleaner alternative fuels, and accelerates the use of alternative fuel vehicles and the establishment of local refueling stations. Its major goal is to reduce U.S. reliance on foreign fuel sources but air quality benefits also are realized through this program. Alternative fuels (ethanol, biodiesel, and compressed natural gas) produce less pollutant emissions per unit volume than gasoline and diesel.

Rainwater Harvesting

Water conservation in a Sonoran Desert community is an important practice with many benefits. Broad-based use of rainwater harvesting can reduce municipal water demand by lowering the need for potable water for outdoor use (over a third of Tucson’s household water use). The pumping, delivery and treatment of water requires a great deal of energy. Reducing water use also reduces energy use and the greenhouse gas emissions resulting from the production of electricity needed to deliver the water. Rainwater harvesting, a practice supported through PAG’s Stormwater Program, captures or slows the movement of surface stormwater so it can be put to beneficial use.

Stormwater Pollution Prevention

PAG’s Stormwater Program coordinates a pollution prevention outreach on behalf of its member jurisdictions through its annual Clean Water Starts With Me campaign. Simple acts like picking up after your pet and keeping your vehicle maintained, can help keep our washes clean.

Southern Arizona Regional Solar Partnership

The Southern Arizona Regional Solar Partnership, managed by PAG, is a cooperative effort focusing on this region’s natural opportunities for using solar energy. This partnership encourages the expansion of solar-based systems to reduce our reliance on other energy sources that generate greenhouse gases.

Sustainable Action Plan

In August 2008, the Pima County Board of Supervisors unanimously adopted the Sustainable Action Plan for County Operations. This 5-year plan recommends specific programs for enhancing practices for water conservation and management, green building, renewable energy and energy efficiency, alternative fuel vehicles and other sustainable practices. Since 2008, County staff has incorporated a wide range of programs that integrate sustainable practices into all aspects of county government operations. Its FY 2011-12 Sustainability Report Card, charts the progress of the action plan’s implementation after four years of work to reduce energy use and greenhouse gas emissions.

Mayor’s Climate Protection Agreement

In 2006, Mayor and Council adopted the Mayor’s Climate Protection Agreement, thereby committing Tucson to reduce greenhouse gas emissions to 7 percent below the 1990 levels by 2012. In 2008, the Mayor and Council authorized the formation of the Climate Change Advisory Committee to guide City staff on the implementation of the agreement. The Committee along with others developed the first phase of greenhouse gas reduction measures which was approved by the Mayor and Council in December 2011.

The Committee is currently developing a Climate Change Adaptation Plan, a guide for the community on ways to adjust to the environmental changes due to climate change in the desert Southwest.

Pima County and Tucson Collaborative Programs

Pima County and Tucson have developed Green Building programs and a Net-Zero Energy Building Code to provide builders with information on designing energy-efficient private and commercial buildings.

Marana had initiated a Green Building and Sustainability program, which incorporates energy efficiency and conservation, stormwater protection program and has initiated the development of green building initiatives.

Oro Valley’s Town Council also signed the Mayor’s Climate Protection Agreement in 2009, committing the town to reducing greenhouse gas emissions. Oro Valley has developed various programs to promote water and energy conservation.

Sahuarita’s General Plan>promotes sustainability through environmental planning, water and energy conservation and land use planning. Sahuarita also has a Green Residential Building Program> in place that provides information to builders, developers and home owners on ways to reduce energy and water use.

Office of the Governor

In 2005, Governor Napolitano signed Executive Order 2005-02, which established a Climate Change Advisory Group, charged with developing a statewide GHG inventory and a Climate Change Action Plan for reducing GHG.

In 2006, Governor Napolitano signed Executive Order 2006-13 which set goals for reducing greenhouse gas emissions to 2000 levels by 2020, and further reducing greenhouse gas emissions by 50 percent below the 2000 levels by 2040. In addition to setting reduction goals, the Executive Order charged the Climate Change Advisory Group with developing strategies for implementing the Climate Action Plan.

In 2010, Governor Brewer signed Executive Order 2010-14, recognizing the need to reduce Arizona’s greenhouse emissions and affirmed state representatives’ continued participation in regional climate change advisory groups.

Additionally, various state agencies are involved in managing the effects of climate change and in promoting clean energy and sustainability.

Arizona Corporation Commission

In 2006, the Arizona Corporation Commission approved the Renewable Energy Standard and Tariff (REST). These rules require regulated electric utilities to generate 15 percent of their energy from renewable resources by 2025. The Commission’s Standards encourage utilities to use solar, wind, biomass, biogas, geothermal and other similar technologies to generate clean energy to power Arizona’s future.

In 2010, the Arizona Corporation Commission passed the Electricity Energy Efficiency Rules and the Natural Gas Efficiency Rules. The electricity rules require public utilities to design programs that are cost effective and promote energy efficiency, by providing tools and incentives for customers to reduce their energy usage, thereby lowering their energy bills. Arizona’s public utilities are required to achieve annual energy savings of at least 22 percent by 2020. Gas utilities will be required to achieve annual energy savings of at least 6 percent by 2020.