Some solutions are relatively simple and would provide economic benefits: implementing measures to conserve energy, putting a price on carbon through taxes and cap-and-trade and shifting from fossil fuels to clean and renewable energy sources.

Of course we have to use coal... the renewable energy sources will supplement the supply from coal.

I spent more than 20 years of my professional career researching and developing renewable energy sources.

We should not just consume hydrocarbon fuel but use it to develop nuclear energy, hydro power and renewable energy sources.

Just as fossil fuels from conventional sources are finite and are becoming depleted, those from difficult sources will also run out. If we put all our energy and resources into continued fossil fuel extraction, we will have lost an opportunity to have invested in renewable energy.

It's going to cost trillions of dollars to rework the energy sources all over the world. Were going to have to move away from fossil fuels.