About 150 people in Edinburgh joined in yesterday's International Day of Climate Action by forming a human "350" outside the Scottish Parliament building at Holyrood.
The Edinburgh event was one of 5,200 events taking place within 24 hours in 181 countries across the planet highlighting the importance of getting co2 emissions in the atmosphere below 350 parts per million.
350 ppm originally came from a NASA research team headed by American climate scientist James Hansen, which surveyed both real-time climate observations and emerging paleo-climatic data in January of 2008.
Their peer-reviewed article concluded that above 350ppm co2 the earth’s atmosphere couldn’t support "a planet similar to the one on which civilization developed and to which life on earth is adapted."
"It’s a very tough number," says Bill McKibben, founder of www.350.org, who wrote the first book on Climate Change for a general audience in 1989.
"We’re already well past it — the atmosphere holds 390 ppm today, which is why the Arctic is melting and the ocean steadily acidifying. To get back to the safe level we need a very rapid halt to the use of coal, gas and oil so that forests and oceans can absorb some of that carbon."
In Edinburgh, a march led down the Royal Mile from the City Chambers to the Scottish Parliament at Holyrood where Keith Baker, of local 350 campaign group www.Holyrood350.org, organised people into a large 3, a 5 and an 0 in the wind and rain.
Similar public actions are expected to take place in the run-up to the United Nations Climate Change conference in Copenhagen in December.
Leaders of the world will be negotiating a global plan to replace the Kyoto Accord and, it is hoped, that will be enough to prevent the catastrophic effects of runaway Climate Change.