According to the US Environmental Protection Agency, the Earth's average temperature has risen by 1.4°F over the past century, and is projected to rise another two degrees to 11.5°F over the next 100 years [Source]. Small changes in the average temperature of the planet can translate to large and potentially dangerous shifts in climate and weather, which will impact California [Source].
Greenhouses gases (GHGs) are the cause. GHGs surround the earth like a blanket, trapping energy in the atmosphere and causing it to warm. The “greenhouse effect” is natural and necessary to support life. However, the build up of GHGs because of human activity is greater than the earth can compensate for and the temperature is slowing rising.
The main greenhouse gases
Carbon dioxide (CO2) enters the atmosphere through burning fossil fuels (coal, natural gas and oil), solid waste, trees and wood products, and also as a result of certain chemical reactions (e.g., manufacture of cement). Carbon dioxide is removed from the atmosphere (or "sequestered") when it is absorbed by plants as part of the biological carbon cycle.
Methane (CH4) is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from livestock and other agricultural practices and by the decay of organic waste in municipal solid waste landfills.
Nitrous oxide (N2O) is emitted during agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.
Fluorinated gases, including hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride, are synthetic, powerful greenhouse gases that are emitted from a variety of industrial processes, including refrigerants used in air conditioning systems, aerosol propellants and by-products from manufacturing silicon chips.
What causes greenhouse gases?
The California Air Resources Board conducts a regular survey of GHGs and the most recent report indicates that 38 percent of GHGs come from transportation [Read more]. Electricity generation is the next largest contributor at 23 percent. (This is quite different from the EPA’s national totals because California has very little coal-fired electricity [Source]). Overall, 73 percent of statewide GHGs are tied to fuel from burning natural gas to make electricity to emissions from transportation fuel.
Addressing global warming
In 2006, the California Global Warming Solutions Act (AB 32) established the goal of reducing greenhouse gases to 1990 levels by 2020. An executive order issued by Gov. Schwarzenegger and reinforced by Gov. Brown called for reducing GHGs a total of 80 percent by 2050 through cleaner electricity and transportation.
Fuel cell electric vehicles have zero tailpipe greenhouse gas emissions. When making the hydrogen from natural gas, as most hydrogen is made today, the GHG emissions are cut in half compared to a conventional vehicle using gasoline. When the hydrogen comes from renewable sources, like electrolysis of water or using biogas, the greenhouse gas emissions are nearly zero.
Meeting the 2050 goal for reducing GHGs will require nearly 100 percent of passenger vehicles sold by 2040 to be zero-emission vehicles (ZEVs), including fuel cell and battery electrics. The Advanced Clean Cars Program is one way that California is helping to bring ZEVs to market.