Quantity and Quality of Soil Carbon Sequestration Control Rates of Co2 and Climate Stabilization at Safe Levels
Author: Tom Goreau | Published: May 3, 2017
Today’s CO2 atmosphere concentrations will lead to devastating increases in global temperatures and sea level over the thousands of years that cold deep ocean waters warm up, even if no more fossil fuel CO2 is added. Long-term impacts shown by climate records are much greater than IPCC projections, which are politically mandated to only include short-term initial responses. They ignore 90% or more of the long-term climate impacts that will affect future generations for millions of years unless CO2 is rapidly reduced to pre-industrial levels, giving policy makers a false sense of security. Even complete emissions reductions cannot remove the existing CO2 excess already in the atmosphere, only increased carbon sinks can do so, and only soil has the capacity to store it in time to avert runaway climate change. CO2 can be reduced to safe levels in decades if 1) current carbon farming sequestration practices are applied on a large scale, 2) lifetime of soil carbon storage is increased with biochar, and 3) with large scale restoration of coastal marine wetland peat soils, especially using new electrical stimulation methods. Regenerative Development strategies to reverse climate change by increasing soil and biomass carbon need to be implemented by UNFCCC.
Keywords: CO2 sequestration, soil carbon, lifetime, burial rates, stabilization time, reversing climate change, regenerative development
Introduction, scope and main objectives
Climate change strategies claiming that 2 degrees C warming or 350 ppm are “acceptable” sentence coral reefs and low lying countries to death. Corals are already at their upper temperature limit (Goreau & Hayes, 1994). The last time global temperatures were 1-2 C warmer than today, sea levels were 6-8 meters higher, equatorial coral reefs died from heat, crocodiles and hippotamuses lived in London, England, yet CO2 was only 270 ppm (Goreau, 1990; Koenigswald, 2006, 2011).
CO2 in the atmosphere (>400ppm) is already way above the pre-industrial (270ppm) levels consistent with modern global temperature and sea level, and millions of years of ice core and deep sea climate records show that current atmospheric CO2 levels will lead, over thousands of years, to steady state global temperatures and sea levels around 17 degrees Celsius and 23 meters higher than modern levels (Goreau 1990, 2014; Rohling et al., 2009).
It takes thousands of years for this response to happen to the CO2 already in the air because the deep ocean, which is around 4 degrees Celsius and holds nearly 95% of the heat in the earth climate system, takes 1600 years to turn over, and until the deep ocean warms up we won’t feel the full effect at the surface. This time lag is ignored in IPCC projections. Once the earth enters a super Greenhouse, like those the last time when CO2 was last 400 ppm millions of years ago, temperatures and sea levels were indeed around 17 celsius and 23 meters higher respectively (Rohling et al., 2009). The excess CO2 (and temperatures) will take from hundreds of thousands of years to millions of years to be finally buried in sediments and geologically removed from the system (Goreau, 1995). The oceans cannot serve as a major sink without turning them into dead zones stinking of hydrogen sulfide and devoid of life above bacteria.
However, there is a vastly faster biological short-circuit to the slow geological burial of CO2, namely rapid enhancement of biomass and soil carbon sinks, especially in the tropics, which could stabilize CO2 at safe levels rapidly (Goreau, 1987, 1990, 1995, 2014). Worldwide we have already lost about half the carbon in the Earth’s living biomass, and about half the carbon in soils that have been converted to farming and grazing, but restoring these natural CO2 sinks (“Geotherapy”) can absorb excess fossil fuel carbon at the lowest cost.
Main objectives:
1) Identify scientifically-sound safe CO2 levels from climate records
2) Determine how quickly CO2 can be stabilized to prevent extinction of coral reefs and flooding of low-lying coasts, based on quantity and quality (long-lived fraction) of soil carbon sequestration and global atmospheric CO2 input-output models.
3) Identify the specific methods and locations for the fastest and most effective reduction of CO2 to safe levels.
Methodology
The rate at which CO2 can be stored in soil can be done depends on the quantity and quality (in terms of lifetime) of carbon sequestration, and the target. The “safe” CO2 target in terms of global temperature and sea level changes is identified as preindustrial CO2 levels from nearly a million years of Antarctic Ice Core, fossil coral, and deep sea sediment climate records.
IPCC model projections are not used because they seriously under-estimate long term impacts due to use of the wrong time horizons for calculating impacts. Steady-state temperature and sea level for TODAY’S 400 ppm CO2 level are around 17 degrees C warmer and 23 meter higher than now (Rohling et al.: 2009; Goreau, 1990, 2014), and it takes thousands of years for the deep ocean to warm up, only then we will feel full impacts. IPCC estimates don’t include this lag.
To meet global Geotherapy goals of restoring planetary life support systems to health, not only is increased soil carbon storage needed in every terrestrial habitat and ecosystem, but increases in soil carbon storage lifetime will also be essential. We calculate here how long it takes to reduce atmospheric CO2 to safe preindustrial levels and show the results graphically as a function of the global increase in net carbon burial on the land surface (the soil carbon sequestration quantity parameter), and as a function of the fraction of long-lived carbon that does not decompose (the soil carbon sequestration quality parameter).
Results
Current agricultural practices only return about one ton of carbon per hectare per year, and very little of this, perhaps 1% is long lived, so typical practices would take thousands of years to drawdown the excess, coral reefs will die, and coasts flood. On the other hand, best practice carbon farming is capable of burying tens of tons per hectare per year (Toensmeier, 2016), and using biochar up to tens of percent of soil carbon can be long lived, which would allow the dangerous excess CO2 to be removed in decades, and avert the worst runaway global climate change impacts (Figures 1 & 2).