- 350 PPM, not 450, should be our target

Centre partner SEI and Tällberg Foundation unite scientists and global leaders in call for tougher targets in climate negotiations.

On Monday 23 June 2008, full-page advertisements was published simultaneously in the Financial Times, the International Herald Tribune, the New York Times,  and in the Swedish papers Dalarnas tidningar,  carrying the headline "<350". This figure relates to the upper limit for atmospheric Carbon Dioxide. The message in the advertisements is directed towards nations involved in the negotiations leading up to and beyond the Copenhagen Climate Change Conference in December 2009.

See the “<350" ad and a full listing of signatories here.PDF (pdf, 60.7 kB)

- Heading in the wrong direction
The advertisement was initiated by Bo Ekman, founder of the Tällberg Foundation, and is supported by the Stockholm Resilience Centre partner Stockholm Environment Institute and over 170 signatories, including a dozen of the world´s leading environmental scientists, such as James Hansen, Robert Corell and James Lovelock.

Other signatories include Jacqueline McGlade, Executive Director of the European Environment Agency; José Maria Figueres, ex-president of Costa Rica; the former Swedish Prime Minister, Göran Persson; and authors Bill McKibben, Mark Lynas and Tim Flannery.

The parts per million (PPM) of Carbon Dioxide (CO2) in the atmosphere has long been a key indicator for climate change.  Setting a PPM limit is one of the guiding principles behind the ongoing climate negotiations. Several proposals for an upper limit for CO2 have come forward and until recently scientists estimated that the level could reach 450 PPM without threatening life on Earth.

- We are concerned that the negotiations are heading in the wrong direction, said Professor Johan Rockström, Executive Director of the Stockholm Environmental Institute.

- The CO2 threshold under discussion is too high. Today, the scientific community has a pretty clear picture of how much CO2 our atmosphere can sustain, and there is growing evidence that 350 PPM should be our target, rather than 450 PPM. Sadly, this has not yet been reflected in the negotiations, he said.

CO2 emissions increasing by 3 percent annually
The latest studies show that a 450 PPM level of CO2 is expected to cause more than a one meter rise — and perhaps as much as a 3 meter rise — in the sea level during this century, and more than 20 meters over a longer period. The global mean temperature on Earth will increase by 2 degrees Celsius above pre-industrial levels, which carries enormous implications for global and regional ecosystems.

According to James Hansen, “The shocking conclusion I have reached is that the safe level of atmospheric carbon dioxide is no more than 350 parts per million and it may be less.  Today, CO2 emissions are increasing by 3 percent annually. Setting an upper limit of 350 PPM doesn´t just mean stopping this annual increase.  It will mean taking actions that, during this century, will lower the PPM level to less than 350.  Even if we do this, populations across the globe will still have to face significant adaption to climate change."  

- The 350 PPM upper limit is currently a hot topic in the U.S, and according to scientists this is the figure that we have to deal with," said Bo Ekman. 

- We hope that the advertisement will help politicians and decision-makers realize that we cannot negotiate with nature, and that this is the greatest challenge of our time, he said.

See the “<350" ad and a full listing of signatories here.PDF (pdf, 60.7 kB)

Read more about the vision and science behind <350 on the Tällberg website.

Further info

Related info

Tällberg Foundation has during 28 years gathered global readers to discuss our common future. Between 25th-29th June this year, the village of Tällberg welcomes 400 global leaders who will meet and exchange experiences about how on Earth we all can live together. More information at www.tallbergforum.org

This year the Forum, along with the Stockholm Environment Institute and Stockholm Resilience Centre, will host a workshop of 20 of the world´s leading scientists. They´ll discuss and present the Planetary Boudaries within which human development can flourish. 350 PPM is one of those boundaries.


Stockholm Resilience Centre is a collaboration between Stockholm University and the Beijer Institute of Ecological Economics at the Royal Swedish Academy of Sciences

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