The world really has only two sources of energy. The most obvious is the sun, energy that comes to us through space and through the air. The other comes from deep below the ground, energy that was in the Earth when it was formed.

The energy that we get from burning wood comes from the sun, which was the source of energy that made the trees grow. Wind is produced by uneven heating of air by the sun. Cold air is heavier than warm air. The fossil fuels — petroleum, coal and natural gas — were made from remnants of life that have been stored underground for millions of years. The sources include vegetable (plants and trees) and animal (dinosaurs and other creatures) that died. This fossil energy came almost entirely from the sun.

We do get some energy, such as nuclear energy, from basic elements such as uranium and plutonium. In fact, all of the tiny molecules that are listed in the periodic table of the elements are really made of energy. This energy was either in the Earth when it was formed or received from the sun since that time.

We, humans, and all other forms of life, need energy to exist. We get our basic energy by eating food that exists because of the sun, whether it is fruit and vegetables or animals. We also take in oxygen from the air.

Over the centuries, people have used a lot of wood, and the English used up almost all of the trees that existed on their island. Conveniently, they found that they could burn coal and so people began to use fossil fuel.

Now we are using up coal, petroleum and gas that has been stored in the ground. If we continue, someday it will be all gone. We learned some time ago that using this source of energy generates carbon dioxide, which is warming the air so much that it that will make it more difficult for many kinds of life to continue to exist, including humans. This must stop.

Yet we do need energy. Where will it come from? The easy answer is to get the energy we need from the sun. We can do this without contributing to the problem of climate change. We can collect the sun’s energy by heating conductive substances, and now, by using solar panels to change the sun’s energy into electricity. Electricity can be used to propel automobiles, trucks, subways and railroad locomotives. These methods do not cause climate change problems and are renewable, unlike fossil fuel.

Of course, the sun does not shine all the time, but clean energy also can be produced by windmills, rivers and tidal water. Hydroelectric dams can store water when the sun is shining and generate electricity when the sun is not shining.

So why do we continue to develop new sources of fossil fuel when better ways to get energy are available?

I suppose it is because a lot of money has been invested in obtaining fossil fuel energy even though investors have known about the climate change problems since before 1980.

But if we don’t stop doing this, the world and its people are in a lot of trouble. The oceans are rising rapidly. The ocean water is becoming warmer and more acidic, which is destroying its ability to produce food.

Many of the places where we have grown food for centuries are becoming too dry. Drought-stricken California is getting less rainfall and does not have access to enough river water and underground water to irrigate the farmland. We can’t use salty and acidic ocean water to irrigate farmland.

Hopefully, the international conference in Paris this month relating to climate change will solve some of our problems, before it is too late. Hopefully, all governments will take action to require transition from fossil fuel energy to other sources and do so as quickly as possible, whether privately owned fossil fuel corporations want to or not.

Elery Keene of Winslow spent 31 years as executive director of the Kennebec Valley Council of Governments.