The future means to sustain conditions for civilizations to keep the climate in balance, to avoid all the bad stuff scientist predict might happen when we keep burning fossil fuels. Today begins another climate conference with the aim to get an agreement done, which involves all the nations of planet Earth. The 2015 United Nations Climate Change Conference, or COP21 will conclude on December 11, the first conference was held back in 1992.
Professor Stefan Rahmstorf pointed out: In November 1965, US President Lyndon B. Johnson was presented with the first-ever government report warning of the dangers that could result from burning large amounts of fossil fuels. Fifty years is a long time in politics, so it is remarkable how little has been done since then to address the threat posed by carrying on with business as usual.
In remarkably prescient language, Johnson’s scientific advisory committee warned that releasing carbon dioxide into the atmosphere would lead to higher global temperatures, causing ice caps to melt and sea levels to rise rapidly. “Man is unwittingly conducting a vast geophysical experiment,” warned the scientists. “Within a few generations he is burning the fossil fuels that slowly accumulated in the earth over the past 500 million years…The climatic changes that may be produced by the increased CO2 content could be deleterious from the point of view of human beings.”
Today the discussion evolves around the so called 2C target, which some consider to be a turning point. But the ultimate indicator for our climate is ultimately measured by the amount of CO2 in our atmosphere. The naming for the 350.org movement makes this very clear. But even with 350 ppm of CO2, we would be still in the realm of potential disasters, feedbacks, climate chaos.
Hansen et al 2008 noted: Paleoclimate data show that climate sensitivity is ~3°C for doubled CO2, including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, is ~6°C for doubled CO2 for the range of climate states between glacial conditions and ice-free Antarctica. Decreasing CO2 was the main cause of a cooling trend that began 50 million years ago, the planet being nearly ice-free until CO2 fell to 450 ± 100 ppm; barring prompt policy changes, that critical level will be passed, in the opposite direction, within decades.
If humanity wishes to preserve a planet similar to that on which civilization developed and to which life on Earth is adapted, paleoclimate evidence and ongoing climate change suggest that CO2 will need to be reduced from its current 385 ppm to at most 350 ppm, but likely less than that. The largest uncertainty in the target arises from possible changes of non-CO2 forcings. An initial 350 ppm CO2 target may be achievable by phasing out coal use except where CO2 is captured and adopting agricultural and forestry practices that sequester carbon. If the present overshoot of this target CO2 is not brief, there is a possibility of seeding irreversible catastrophic effects.
CO2 in Deep Time
Carbon dioxide in Earth’s atmosphere: There is evidence for very high CO2 volume concentrations between 200 and 150 million years ago of over 3,000 ppm, and between 600 and 400 million years ago of over 6,000 ppm. In more recent times, atmospheric CO2 concentration continued to fall after about 60 million years ago. About 34 million years ago, the time of the Eocene–Oligocene extinction event and when the Antarctic ice sheet started to take its current form, CO2 is found to have been about 760 ppm, and there is geochemical evidence that concentrations were less than 300 ppm by about 20 million years ago. Carbon dioxide decrease, with a tipping point of 600 ppm, was the primary agent forcing Antarctic glaciation. Low CO2 concentrations may have been the stimulus that favored the evolution of C4 plants, which increased greatly in abundance between 7 and 5 million years ago.
Above image from the Antarctic Vostock records indicate that the CO2 amount has been relatively stable for at least the past 420.000 years. And more ice core data reveals that it has been relatively balanced for at least 800.000 years.
Indeed as another study concluded back in 2009, “The only time in the last 20 million years that we find evidence for carbon dioxide levels similar to the modern level of 387 parts per million was 15 to 20 million years ago, when the planet was dramatically different.”
Sure there were times in the geological past when the planet had higher figures. But one has to look at the conditions of those times, these weren’t conditions which favored live as we know it today. Intelligent life only begun to form once CO2 levels dropped below 300 ppm.
With about 400 ppm CO2 currently observed we can assume that the climate and the conditions will adjust to analog records. That means that with the current amount of CO2 we have a situation, which is very likely the precursor for much higher temperatures, as below image indicates.
If the Paris outcome today doesn’t result in large reductions of emissions, the system might balance out with much higher temperatures, which would mean we are heading for the ice free planet state. Which would mean that billions of people need to move away from the rising tides. And because of the rate of change we will likely see many ecosystems collapse, which in turn threatens civilization.
Natural climate change can not be compared to our current situation, since natural change takes normally thousand of years to reach thresholds, an asteroid impact would only create a single impulse in the record. What we do is to apply a constant and growing emission uptake within a very short geological time. Even when the Ocean currently takes up most of our emissions, at one point it will be saturated enough and likely result in tipping points, when response from natural systems add additional climate forcing.
Even now we risk abrupt developments, which could mean sudden temperature changes, different atmospheric regimes, or additional release of greenhouse gases through ecosystems. And all this would mean an existential threat to our food supplies. When climatic zones shift, when the tide rises we might be able to move, but we cannot move farm land, and we cannot move all the other species we need.
We must act today. We ow this to our children, future generations, and to preserve what we call our home. There is no more time for delay. If you delay climate action you are a threat for the survival of the human species.