- Global warming poses one of the greatest threats to society and the economy, requiring 15-30% cuts in greenhouse gas emissions by 2020 and deeper 60-80% cuts by 2050 to limit temperature rise. - Information and communication technology (ICT) can both directly reduce its own 2-3% share of emissions and enable much larger indirect emission reductions in other sectors like transportation and buildings. - A "zero carbon" strategy of relocating ICT infrastructure to remote renewable energy sites powered by wind and solar is proposed, using optical networks to connect to users. This could make growth in ICT services carbon neutral.