"Remember this number for the rest of your life."

The world is starting to realise that the goal of 450 ppm as a reasonable level to balance and stabilize the CO2 in our atmosphere is based on wrong and outdated science and won’t be enough to stop man-made climate change.

More and more scientific reports show that the older science has been too "soft" in their climate change calculations. For example, we can already now see a never ending and rapid melting of the Arctic ice, something that "would happen in 20-30 years" according to the older science reports. Scientific reports earlier projected that the Arctic would become ice-free by year 2050. But newly released reports suggest it could happen as early as 2013.

450 ppm is wrong. 350 ppm is, and should be, the new goal.

We are currently at 385-387 ppm and that number is increasing faster for each day that passes by with no end in sight. That means we won’t be able to just stop or lower our greenhouse gas emissions. We need to stop and even negate all emissions.

No wonder the world's leaders are choosing to ignore the number 350.

The yearly Tallberg Forum, in Tällberg, Sweden, is about to start. During the five days the forum is held hundreds of people from around the world will discuss "how, on Earth, can we live together?" One of their main talking points will be the Earth's limits and especially the 350 ppm CO2 limit.

Yesterday the Tällberg Foundation published a full page ad in the New York Times, the Financial Times and the International Herald Tribune with the title "350. Remember this number for the rest of your life."

The full page ad was signed by 150 of the world's most respected climate scientists, politicians and business leaders calling upon "all nations in the ongoing climate negotiations to adopt 350 as the target to be reached peacefully and deliberately, with all possible speed".