Uninhabitable Earth, or merely the “Anthropocene”— humans altering the planet to the point where the changes are visible in the geological record, ringing in a new epoch. A team led by Earth systems scientists Johan Rockström and Will Steffen developed the concept of “planetary boundaries” (Figure1.1) in 2009. They identified nine major systems where humans were altering fundamental Earth systems—from climate change to land-system change to stratospheric ozone and gave us now-infamous spider graphs summarizing the all-too dire warnings. The green zone is the safe operating space, the yellow represents the zone of uncertainty (increasing risk), and the red is a high-risk zone. The planetary boundary itself lies at the intersection of the green and yellow zones. The control variables have been normalized for the zone of uncertainty; the centre of the figure, therefore, does not represent values of 0 for the control variables. The control variable shown for climate change is atmospheric CO2 concentration. Grey wedges represent processes for which global-level boundaries cannot yet be quantified; these are atmospheric aerosol loading, novel entities, and the functional role of biosphere integrity. “Planetary boundaries” is a concept involving Earth system processes that contain environmental boundaries. Beyond zone of uncertainty (high risk) In zone of uncertainty (increasing risk) Below boundry (safe) Boundary not yet quantified Role of agriculture
Figure 1.1 Current status of the control variables for seven of the planetary boundaries. The green zone is the safe operating space, the yellow represents the zone of uncertainty (increasing risk), and the red is a high-risk zone. The planetary boundary itself lies at the intersection of the green and yellow zones. (Source: Will Steffen (2015))
Climate Change To discuss the issue about climate change, it is better to consider four types of Carbon dioxide emission (Figure 1.2 (a)) prediction that mentioned by IPCC, RCP2.6 (representative concentration pathways), RCP4.5, RCP6.0, and RCP8.5. Warming will continue beyond 2100 under 3 | Introduction
