SAN FRANCISCO: The head of Microsoft Corp's $9 billion research unit thinks the debate over stopping climate change is being muddied by talk of renewable energy.

Efforts should be focused on stopping output of carbon dioxide, the greenhouse gas which helps heat the planet, rather than moving to a source that can be regenerated, said Craig Mundie, the man who replaced Bill Gates as the world's largest software maker's futurist.

Conservation and radical technologies, including new nuclear, could be key, he said.