In the last post, we discussed the time frame for the upcoming global warming disaster (40 to 90 years) and one of the three tools at our disposal to mitigate the impact - specifically the reduction of GHG emissions. This post will discuss two other tools: GHG "sinks" and engineering and technology solutions.
Carbon Dioxide Sinks
"Sinks" absorb and trap greenhouse gases. Forests, soil and oceans are three natural sinks.
A significant portion of the current higher levels of CO2 in the atmosphere is due to land use and development. The World Research Institue estimates that 18% of GHG emissions comes from land use changes. Specifically, deforestation reduces the amount of CO2 that can be absorbed via photosynthesis. As Tim Flannery writes in his recently published Here on Earth: "By 2009, around half of the tropical forests present in 1800 had been destroyed and, at the current rate of destruction, by 2050 most of the remainder outside protected areas will be gone as well." One solution to this is sustainable forestry enforced by a global treaty (for example, certification that forest products have been harvested sustainably). Another would be a ban on logging in old growth forests.
Soil presents an even larger total sink for CO2 than vegetation. The burning and natural decomposition of trees and agricultural matter contributes a large amount of CO2 being released to the atmosphere. Biochar can potentially store this carbon in the ground, thereby making a significant reduction in atmospheric GHG levels. The carbon in CO2 can be mineralized in charcoal and "biochar" using a technology called pyrolysis. Pyrolysis involves the burning of biomass in the absence of oxygen. The mineralized carbon can then be stored stably for hundreds or thousands of years by mixing it back in to the soil. Biochar also has a beneficial effect on the soil itself. It can improve plant yields for certain types of crops, improve water quality, reduce soil emissions of GHGs, reduce leaching of nutrients, reduce soil acidity, and reduce irrigation and fertilizer requirements. The UK's Royal Society has estimated that widespread application of this technology for sequestering carbon can reduce atmospheric CO2 levels by 50 to 150 ppm.
By far, the largest CO2 sink that we have is the oceans. That's the good news. The bad news as reported in a 2009 ScienceDaily article: "The oceans are the planet's main carbon sink, but in the last ten years they have become increasingly unable to play this role, in both the northern and southern hemispheres." As atmospheric CO2 levels increase and water temperatures increase, the oceans can absorb less and less CO2. The only solution to this is to reverse the trend of increased human-indiced emissions.
Engineering and Technology
The last tool to be discussed is engineering and technology solutions to protect coastal cities, shorelines, and food supply. Regardless of what steps we take to reduce emissions and increase the absorptive capacity of the land and oceans, there will be a signicant negative effect of the ongoing human-induced global warming. The extent to which we will need engineering solutions will depend on the extent we are able to reduce CO2 levels. If we do nothing, then the cost of the engineering solutions will be high. If we do much, then the cost of the engineering solutions will not be quite as high.
And if we do nothing at all - if we neither reduce atmospheric GHG levels nor provide mitigation by engineering solutions - the cost will be many trillions of dollars in damages and, globally, literally billions of displaced persons.
Dikes, levees and water removal systems for coastal cities will need to be constructed or improved. Improved heat-resistant crops with low water requirements will need to be developed. By 2050, the world's population will increase 50% to 9 billion. Let's hope we all do the right things to sustain these people of the future.
Global Political Will
More than anything else, the success or failure of the efforts to mitigate the effect of human-induced global warming depends on the political will of the nations of the world - the ability to think long-term and to cooperate globally. The United States, as one of the leading contributors to the current problem, must also be a leader in its solution. If the Know-Nothing's of today are really concerned about the world they will leave to their children and grandchildren, they better think about what the overwhelming scientific evidence is showing. Why not give the world an example of American exceptionalism in the best possible way by leading this effort ?
Final Note: For forecasts of the economic and human impacts, please see the Global Warming Forecasts website.
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