Many of the events were held as part of a worldwide climate change campaign by the international environmental group 350.org.
The figure represents 350 parts per million of carbon dioxide in the atmosphere -- the amount some scientists say must be reached for a safe CO2 limit. According to 350.org">350.org, the actual atmospheric concentration of CO2 is 390 parts per million.
Activists put on awareness events across Asia.
In Sydney, Australia, an estimated 2,000 protesters with umbrellas sat on the Opera House steps to spell out "350.org">350."
Climate change activists also converged on European capitals, trying to mobilize public opinion in the run up to next month's international climate conference in Copenhagen.