We provide a method to estimate how to determine the amount of carbon to remove to affect the cumulative emitted anthropogenic carbon dioxide for Carbon Dioxide Removal (CDR) targets when climate modeling is unavailable. Additionally, comparing the growth in anthropogenic carbon dioxide emissions to the late-Holocene atmospheric carbon dioxide concentration for historical context and present hypothetical emissions declines for climate restoration. We explore the recent historical context of cumulative anthropogenic carbon dioxide emissions and how it has induced increases to each of the natural sinks: the oceans, atmosphere, and land. The magnitude of cumulative emissions is obscured when only considering yearly emissions change. A possible baseline CO2 concentration of 280.9 ± 0.9 ppm for pre-human change stretching from 600 BCE to 1750 CE was found and could be explored separately. We show multiple speculative emission declines to zero cumulative CO2 emissions to reach complete climate restoration. For groups seeking climate restoration, which completes in less than half a human lifespan, a pair of emission declines are presented, which complete in twenty years. The declines bound a possibility horizon of complete climate restoration ending with 2100 targets. There is a tradeoff between how fast the climate can be restored compared to how long humans can continue to emit carbon dioxide from the use of fossil fuels and land use change. We conclude with hypothesized climate reversibility through hypothesized emissions declines.
Speculations extend the opportunity space of possible future climates by increasing the potential to provide plausible estimated qualities and quantities to further scientific research and aid engineering solutions. This novel work outlines the first steps to achieving an Anthropocene reversal that completes in Zoomers’ lifetimes — by 2100. The novel experimental high-scale carbon removal pathway, which was studied in MAGICC 6.8, required CDR to counterbalance all accumulated anthropogenic emissions since 1750 to return to preindustrial temperature (0.07ºC over the 1720-1800 and 0.14ºC over the 1850-1900) means by 2100 and complete GHG phaseouts by 2077, excluding Ammonia. The experimental pathway set extreme front loading of emissions reductions to reach net zero, and avoid tipping points, then achieve scaled removal to reach 300 ppm of CO2 concentration by roughly mid-century. This work’s findings recommend exploring carbon removal of cumulative anthropogenic emissions totaling 600 GtC to 775 GtC on a recent model ensemble with 1.55 to 1.7 times preindustrial CO2 concentration driven by forcings from emissions and calibrate to reproduce present-day temperatures to provide more detailed projections of temperature, holding below 1.5ºC, regional temperatures, below ground CO2 mineralization, sea-level rise, ENSO, AMOC, and jet-stream turnover, evolve. Continued fossil-fuel use is unable to yield complete emissions phaseouts or deep removals necessary to match a preindustrial climate. The findings support the utmost urgency to attain a maximally scaled sustainable zero-carbon intensity green growth development. And reinforce the increased global commitment to achieve net zero sooner and to avoid setting off more climate tipping points. The possibility of reaching a preindustrial climate should help inform the debate of maximally scaled sustainable green growth development for the fastest path to net zero, phase out of anthropogenic emissions sources, and scaled carbon removals with zero-carbon intensity to develop a more equal future world.