Bill Gates has a lot of money and power. So when he gives the American public a wake-up call, as he recently did, people listen. In February, Gates announced that his top priority is getting the world to zero climate emissions. The way to achieve this objective: create a global society that uses only climate-neutral energy. That's a pretty tall order.

Gates promised to use his philanthropic foundation to improve public health and help alleviate poverty, and news reports say that it's precisely because he wants to improve the lives of vulnerable people that he believes climate change is the most important challenge for the world to address. In his speech, he said we need to eliminate carbon emissions and achieve no net emissions in the developed world by the year 2050.

In his speech, Gates broke down how climate emissions produced by humans result from four main factors: Population growth, services that provide prosperity, energy (in the form of the amount it takes to produce and provide goods and services) and carbon generated to produce the energy it takes to fuel prosperity. Environmentalists argue that we need to focus on the last factor-the carbon intensity of energy.

Gates supports the development of reactors fueled by nuclear waste from disposal facilities or generated by today's power plants. He said this is more reliable than wind and solar, and cleaner than burning coal or natural gas, and safer than current nuclear plants. Of course, there is the problem of plant meltdowns, which would be environmental tragedies. Not to mention, nuclear energy is not the most cost-effective form of alternative energy.

Speaking of nuclear energy, in February, President Obama announced more than $ 8 billion in federal loan guarantees for the construction of a nuclear power plant, which would be the first one built in the United States in nearly three decades. Environmentalists' opposition, safety concerns and the massive cost of reactors have prevented the development of plants since the early 1980s. The federal loans will help fund the construction and operation of two reactors in Burke County, Georgia. When the project finishes in 2017, the plant will generate power for about 1.4 million people. As part of Obama's comprehensive energy agenda, he says that nuclear energy will reduce US dependence on foreign oil and fossil fuels, such as from coal-fired power plants.

As Obama and Gates advocate for nuclear energy, environmentalists continue to promote renewable energy, including solar, wind and geothermal. For instance, wind power as one type of energy is replenishable, widely distributed and produces no greenhouse-gas emissions. Wind is used to make electricity, supply mechanical power and pump water. Solar power is another non-carbon source of energy, which means it doesn't contribute to global warming. Geothermal uses the earth's heat to heat and cool buildings.

There's another major element environmentalists are focusing on in the quest for achieving carbon neutrality in the near future: green building. In the United States alone, buildings account for 38 percent of all carbon-dioxide emissions. Sustainable buildings integrate energy efficiency, water conservation, improved air quality, recycled materials and design innovation. This eco-conscious building philosophy and practice will go far in reducing the carbon emissions that contribute to global warming.

Gates touched upon something very important when he said the world needs to use climate-neutral energy. If we're going to achieve no net emissions by 2050, we need to start the transition today.