The Earth’s climate is changing. The Arctic Ocean is becoming ice-free in the summer, and more than 80 percent of the world’s glaciers are melting. The frequency and strength of hurricanes, tornadoes, floods, heat waves and droughts is increasing. The acidity of the oceans has increased by 30 percent.

Virtually all climate scientists agree that the rising concentration of carbon dioxide is a major factor in climate change. The concentration of carbon dioxide increased from the preindustrial value of about 280 parts per million to 364 ppm in 1997, when the international Kyoto Accord was signed. Even though a major goal of this accord was to limit the rise in carbon dioxide, the concentration has continued to increase to its present value of about 400 ppm.

Last May, the Vatican held a workshop on sustainability that included scientists from around the world. One of the conclusions was that “the massive fossil fuel use at the heart of the global energy system drastically disrupts the Earth’s climate and acidifies the world’s oceans.” The workshop also called for changes in our values and ethics.

Because carbon dioxide stays in the atmosphere for hundreds of years, the burning of fossil fuels needs to be greatly reduced in order to prevent further climate change. This might best be accomplished by an international agreement for taxes on fossil fuels that gradually increase until very little is burned. Meanwhile, the United States should be a leader in showing how the use of fossil fuels can be minimized. Our per-capita carbon dioxide emissions are three times the global average, but we have the wealth and history of innovation to show how a good life is possible with minimal burning of coal, oil and natural gas.

Already some Americans have eliminated a large part of their personal carbon dioxide emissions (their carbon footprint). We should strive to follow their examples by walking or biking to work, living in houses that require very little heating or cooling, vacationing close to home and buying goods and services that have a minimal carbon footprint.

Those with higher incomes should especially reduce their carbon footprint. They have the resources to upgrade to houses that use minimal energy and can move to locations where they can walk or bike to work or, perhaps, commute using an electric car. They can afford to purchase green electricity and should consider photovoltaic panels or solar hot water for their houses. If people of higher incomes spend less on fossil fuels, vacation travel and purchase fewer carbon intensive goods and services, their incomes may substantially exceed their expenditures. As a result, they could retire earlier or reduce their working hours.

This would have the benefit of creating jobs for those displaced either from fossil fuel industries or from jobs that produce goods and services that have a large carbon footprint. They could also make investments in the enterprises needed for the transition away from fossil fuels. Possibilities include renewable energy sources, products and services that increase energy efficiency, and the construction and retrofitting of more energy-efficient houses, apartments and commercial buildings.

Climate change is already having negative consequences for many people. It is urgent that we greatly reduce the burning of fossil fuels before the effects get worse. Half measures such as switching from oil to natural gas, while much better than nothing, are not sufficient. The atmospheric concentration of carbon dioxide continues to increase rapidly, and the need for action is immediate. Obtaining energy from wind, solar, hydro, biomass and other sources is becoming practical, and we can reduce our energy needs by increasing efficiency and simply consuming less.

Effective international treaties need to be enacted as soon as possible to reduce global carbon dioxide concentrations. Meanwhile, we all need to reduce our personal carbon footprint. By doing so we can save money, set an example for others and support the new technologies and lifestyles that are being developed. We are beginning this transition in Maine via increased use of heat pumps, pellet stoves, improved housing, green electricity and locally produced food, but we need to go much further.

John Tjepkema of Orono is a professor emeritus in the School of Biology and Ecology at the University of Maine.