New (March 2008) scientific research was presented in a paper published by Dr James Hansen and nine of the world’s leading climate scientists.

They come to the “shocking conclusion” that the upper limit to the “safe zone” is not 450 ppm but 350 ppm. Further, the findings conclude a “shocking corollary”: the target of 2°C is “a recipe for global disaster, not salvation.”

These conclusions are not based upon theoretical models.

These conclusions are based on paleoclimate data showing how the Earth responded to past levels of greenhouse gases and on observations showing how the world is responding to today’s carbon dioxide amount. These are verified by climate models.

The critical importance of paleoclimate data is that they reveal so-called “slow feedbacks” such as changes as soil composition, melting permafrost and methane release, perennial sea-ice, changes in forests and vegetation and long-term water and carbon cycles creating additional forcings to the climate change process beyond the control of humanity to stop “cataclysmic changes.”

Evidence from the paleoclimate data shows that as the Earth cooled down 50 million years ago, CO2 levels were between 1000 and 2000 ppm. Circa 25 million years ago when CO2 ppm fell to ~450 ppm, Antarctica glaciated. It iced over.

It is uncertain when these slow feedbacks kick-in. But carbon dioxide emissions are currently increasing 3% per year. At this rate, we are 30 years from the 450 ppm level that turned Antarctica into a glacier.

Current observations in the Arctic, Greenland, West Antarctica, glaciers worldwide, and the recent melting of the permafrost regions of Alaska, Canada, and Russia, all demonstrate changes far in advance of the time line presented by the latest IPCC report, all of which strongly suggest that slower feedbacks may be beginning to kick-in.

It should be remembered that in 1988 when Dr James Hansen alerted the US Congress “that the Earth had entered a long-term warming trend, that human-made greenhouse gases almost surely were responsible for the trend, and that global warming enhanced both extremes of the water cycle, meaning stronger droughts and forest fires, on the one hand, but also heavier rains and floods,” CO2 stood at 350 ppm. Hansen said he was 99% certain and the evidence led him to say, “it was time to stop waffling.”

350 ppm is an initial global target. It represents the upper limit of a “safe zone”. To restore the Arctic Sea Ice, other glaciers and other pre-industrial planetary conditions, it may well require reaching a level of 300 to 320 ppm in time, according to the new conclusions.

What does the new science say?

• “All elements for a perfect storm are present.” (Hansen)
• The global mean temperature has risen 0.7-0.8°C since 1850, with most of the increase since 1980.
• More warming –.5°-.7° C – is already “in-the-pipeline,” delayed only by the great inertia of the world oceans.
• Climate can reach points such that amplifying feedbacks spur large rapid changes.
• Arctic sea ice extent is falling dramatically. The Arctic could be ice-free in the summer in five years. In the “old” science, presented February 2007 (IPCC) this process was projected to take 100 years.
• West Antarctic and Greenland ice sheets are vulnerable to even small additional warming. These respond slowly at first, but if disintegration gets well underway it will become unstoppable. If emissions follow a business-as-usual scenario, sea level rise of at least two meters is likely this century, condemning future generations to 20 or more meters of sea level rise.
• As climate zones move farther and faster, climate change will become the primary cause of species extinction. The tipping point for life on the planet will occur when so many interdependent species are lost that ecosystems collapse.
• Arid subtropical climate zones expand poleward with global warming.  Already an average expansion of about 250 miles has occurred, affecting the southern United States, the Mediterranean region, Australia and southern Africa.  Forest fires and evaporation of lakes will increase.
• Mountain glaciers that are the source of fresh water for hundreds of millions of people are rapidly receding world-wide, in the Himalayas, Andes and Rocky Mountains.
• Coral reefs are under stress for several reasons, including warming of the ocean, but especially because of ocean acidification, a direct effect of added carbon dioxide. Ocean life dependent on carbonate shells and skeletons is threatened by dissolution as the ocean becomes more acid.
• During an ice-age global mean temperature is about 2° to 5°C lower than today. Failure of action to lower CO2 levels below 350 ppm could swing the planet into climate changes of the same size – but in the opposite direction. And changes at the speed of 100 years instead of 10,000. This is what global warming is about: can civilization survive outside what Dr Robert Corell terms, “The Anthropogenic Sweet Spot” in which human societies developed over the past 10,000 years?
• “For the last 10,000 years we have been living in a remarkably stable climate that has allowed the whole of human development to take place. In all that time, through the mediaeval warming and the Little Ice Age, there was only a variation of 1°C. Now we see the potential for sudden changes of between 2°C and 6°C. We just don’t know what the world is like at those temperatures. We are climbing rapidly out of mankind’s safe zone into new territory,and we have no idea if we can live in it.” — Robert Corell, Arctic scientist and IPCC member, September 2007

These and other phenomena, confirm that we have already gone too far.  We must draw down atmospheric carbon dioxide, if we wish to preserve the planet we know. Once again, it is time to stop waffling.