Box 2.1 PPM (Parts Per Million) is the measure of concentration of greenhouse gases in the atmosphere.
CO2 eq (Carbon dioxide equivalent) is
a standard unit for measuring carbon footprints. The idea is to express the impact of each different greenhouse gas in terms of the amount of CO2
create the same amount of warming.
Figure 2.1 A quadruple squeeze on humanity’s ability to secure long-term sustainable development on planet Earth. Our planet is under the pressure from (1) population growth and human development, (2) climate change, (3) ecosystem degradation, and (4) the risk of sudden change or surprise when crossing thresholds in ecosystems. The 1st squeeze is characterized by a 20/80 dilemma (bulk of environmental prob- lems so far due to the rich minority, ~20% of the world population, while the remaining ~80% have a right to development). The 2nd squeeze is characterized by the dilemma that we are rushing towards 560 ppm of greenhouse gas concentration (CO2
eq), and we have almost reached 450 ppm, while we need to stabilize at that would
400 ppm to avoid too large risks. The 3rd squeeze has the dilemma that we are rapidly eroding the resilience of Earth, where we so far have undermined 60% of key ecosystem services in support of human wellbeing. The 4th squeeze is the shrinking safe space for human development, due to the need to recognize that surprise is universal in ecosystems and that the way to deal with this is to build in redundancy and buffers; 99% of change occurring as a result of 1% of events, indicating that abrupt change is commonplace.