Cop 21 gets under way today. For those of you for whom the acronym is a mystery, it's got nothing to do with the police and everything to do with climate change. Expectations are high.For the first time in over 20 years of UN negotiations, COP 21, the 2015 Paris Climate Conference, is intended to achieve a legally binding and universal agreement on climate, with the aim of keeping global warming at below 2C by the year 2100.The push factor is the understanding that warming beyond that would set in motion dangerous and probably unstoppable disastrous climate effects, such as melting ice sheets and extreme, deadly heat waves.Over the past 21 years, COP's timeline shows, many milestones have been reached, but there have also been missteps. Alarm bells are now signalling that time is running out for humanity in deciding how the climate change story will pan out.All we have to do is look out of the window to realise that it's not just scaremongering.Heatwaves. Droughts. Torrential rain.We need to sit up and take notice.It's easy to focus on the greenhouse gas emissions from big industry and blame it for polluting our air and water. It would be easy to raise our hands in defeat and say we cannot change how big business behaves.Over the next 12 days, 40 000 diplomats, experts and advocates, including more than 135 world leaders, will meet to discuss how to make the big changes needed.There's a level of optimism in the air for several reasons: the explosive growth and plunging costs of renewable energy production, and increasingly effective societal pressure on governments to act.But that's not enough to get us off the hook. In our daily lives we should look for ways to reduce the damage we do to our planet - walk instead of drive, re-use and recycle.Every bit helps because, as the activists say, there is no Planet B...