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It's not a sure-fire bet, but NASA climate scientist James Hansen and several colleagues have published an article in the latest issue of Global Biogeochemical Cycles making the case that curbing coal emissions alone could forestall a full-blown climate crisis. While they also recommend reducing the use of oil and gas, they estimate that phasing out coal, which has accounted for roughly 80% of emissions growth since the pre-industrial era (and still contributes a healthy slice), over the next few decades could prevent the planet from entering a prolonged period of climate change.
Instead, humans should grow more trees and burn them to produce electricity, capturing and storing the carbon dioxide generated during the process to further mitigate the environmental toll, Hansen told The Independent's Geoffrey Lean.
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Phasing out coal, planting more trees
He also told Lean that all coal plants should be phased out by 2030, at the latest (unless they're retrofitted with carbon capture and storage (CCS) equipment), and that atmospheric carbon dioxide levels should be capped at 350 ppm; the current level is 385 ppm. Widespread implementation of CCS technologies could stabilize the CO2 level around 400 ppm, he believes, after which an international tree planting initiative, paired with better agricultural practices and more CCS, could bring levels to 350 ppm within a century.
Five emissions scenarios equally grim
To reach this conclusion, Hansen and his co-authors devised a set of 5 different emissions scenarios, spanning the years 1850 to 2100 -- each of which reflected a unique fossil fuel peak production scenario:
The remaining three scenarios include the phaseout of coal, but consider different scenarios for oil use and supply. One case considers a delay in the oil peak by about 21 years to 2037. Another considers fewer-than-expected additions to currently proven reserves, or taxes on emissions that makes fuels too expensive to extract. The final scenario looks at emissions from oil fields that peak at different times, extending the peak into a plateau that lasts from 2020-2040.
The team used a mathematical model to convert CO2 emissions from each scenario into estimates of future concentrations in the atmosphere. The "business as usual" scenario resulted in CO2 that would exceed 450 parts per million from by 2035, and climb to more than double the pre-industrial level. Even when low-end estimates of reserves were assumed, the threshold was exceeded from about 2050 onwards. However, the other four scenarios resulted in CO2 levels that peaked in various years, but all fell below the prescribed cap of 450 parts per million by about 2080 at the latest. Levels in two of the scenarios always stayed below the threshold.
More about coal and Hansen
::Nature and Stop Kingsnorth Interview James Hansen about His Clash with Big Coal
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::Coal: Our Nation’s Workhorse