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Over the past century, the total material wealth of humanity has been enhanced. However, in the twenty-first century, we face scarcity in critical resources, the degradation of ecosystem services, and the erosion of the planet’s capability to absorb our wastes. Equity issues remain stubbornly difficult to solve. This situation is novel in its speed, its global scale and its threat to the resilience of the Earth System. The advent of the Anthropence, the time interval in which human activities now rival global geophysical processes, suggests that we need to fundamentally alter our relationship with the planet we inhabit. Many approaches could be adopted, ranging from geoengineering solutions that purposefully manipulate parts of the Earth System to becoming active stewards of our own life support system. The Anthropocene is a reminder that the Holocene, during which complex human societies have developed, has been a stable, accommodating environment and is the only state of the Earth System that we know for sure can support contemporary society. The need to achieve effective planetary stewardship is urgent. As we go further into the Anthropocene, we risk driving the Earth System onto a trajectory toward more hostile states from which we cannot easily return.

Keeping the Earth system in a stable and resilient state, to safeguard Earth's life support systems while ensuring that Earth's benefits, risks, and related responsibilities are equitably shared, constitutes the grand challenge for human development in the Anthropocene. Here, we describe a framework that the recently formed Earth Commission will use to define and quantify target ranges for a “safe and just corridor” that meets these goals. Although “safe” and “just” Earth system targets are interrelated, we see safe as primarily referring to a stable Earth system and just targets as being associated with meeting human needs and reducing exposure to risks. To align safe and just dimensions, we propose to address the equity dimensions of each safe target for Earth system regulating systems and processes. The more stringent of the safe or just target ranges then defines the corridor. Identifying levers of social transformation aimed at meeting the safe and just targets and challenges associated with translating the corridor to actors at multiple scales present scope for future work.

Climate change is an urgent problem. Because it is causing new weather extremes and fatal catastrophes, climate change is better termed climate disruption. Bending the curve to flatten the upward trajectory of pollution emissions responsible for climate disruption is essential in order to protect billions of people from this global threat. Education is a key part of the solution. This textbook book lays out ten solutions that together can bend the curve of climate warming below dangerous levels. These solutions fall into six categories: science, societal transformation, governance, economics, technology, and ecosystem management. Four themes emerge from the book: * There is still time to bend the curve. The time to act was yesterday, but if proper actions are taken now, there is still time to avoid disastrous changes. We have to pull on three levers: The carbon lever to achieve zero net emissions of carbon dioxide before 2050; the short-lived climate pollutants lever to drastically reduce concentrations of other major climate pollutants; and the atmospheric carbon extraction lever to remove massive amounts of carbon dioxide from the atmosphere. * Bending the curve will require interdisciplinary solutions. Climate change requires integrating approaches from the natural sciences, social sciences, and humanities, so this textbook—unlike most on climate change solutions—does just that, with chapters written by experts in climate science, social justice, economics, environmental policy, political science, energy technologies, ecology, and religion. Bending the curve also requires preservation and restoration of ecological systems. * Bending the curve requires a radical shift in attitude. This shift requires change in behavior, change in our attitudes towards each other, and change in our attitude towards nature. Climate justice has to be an integral part of the solution. * Technology, market mechanism and policy need to be a part of the solution. New market mechanisms and other policies are required to spur technological innovations and to scale clean technologies globally.

Fifty-two cities, sixty-three businesses, and several universities have become living laboratories for ambitious climate mitigation programs. By 2050, the total annual emissions for the fifty-two cities will reduce by 407 MMTCO2e (million metric tons), compared with their base period (ranging from 1990 to 2013) emissions, which is equivalent to making the entire state of California, the sixth largest world economy, nearly carbon neutral. Case studies reveal that between 2000 and 2014, California and Sweden grew their Gross Domestic Products (GDPs) by nearly 30% while their CO2e emissions declined by 5% and 24% respectively. Such reductions employ a multitude of action plans, which we place in the context of the Ten Solutions for Carbon Neutrality and Climate Stability published by the University of California. The technologies deployed by the living laboratories include: improving end-use efficiencies; conversion to renewably generated electricity; solving intermittency of solar and wind power with batteries, fuel cells, and hydrogen; developing micro-grids for distributed power generation; expanding use of electric vehicles; recycling reform; capturing agricultural/landfill emissions for conversion to gas; and food waste reduction. The living laboratories have demonstrated that scalable technologies are available now to drastically reduce world-wide carbon emissions. However, doing so requires fundamental behavioral changes.

Fifty-two cities, sixty-three businesses, and several universities have become living laboratories for ambitious climate mitigation programs. By 2050, the total annual emissions for the fifty-two cities will reduce by 407 MMTCO2e (million metric tons), compared with their base period (ranging from 1990 to 2013) emissions, which is equivalent to making the entire state of California, the sixth largest world economy, nearly carbon neutral. Case studies reveal that between 2000 and 2014, California and Sweden grew their Gross Domestic Products (GDPs) by nearly 30% while their CO2e emissions declined by 5% and 24% respectively. Such reductions employ a multitude of action plans, which we place in the context of the Ten Solutions for Carbon Neutrality and Climate Stability published by the University of California. The technologies deployed by the living laboratories include: improving end-use efficiencies; conversion to renewably generated electricity; solving intermittency of solar and wind power with batteries, fuel cells, and hydrogen; developing micro-grids for distributed power generation; expanding use of electric vehicles; recycling reform; capturing agricultural/landfill emissions for conversion to gas; and food waste reduction. The living laboratories have demonstrated that scalable technologies are available now to drastically reduce world-wide carbon emissions. However, doing so requires fundamental behavioral changes.

© 2016, National Academy of Sciences. All rights reserved. The introduction of cloud condensation nuclei and radiative heating by sunlight-absorbing aerosols can modify the thickness and coverage of low clouds, yielding significant radiative forcing of climate. The magnitude and sign of changes in cloud coverage and depth in response to changing aerosols are impacted by turbulent dynamics of the cloudy atmosphere, but integrated measurements of aerosol solar absorption and turbulent fluxes have not been reported thus far. Here we report such integrated measurements made from unmanned aerial vehicles (UAVs) during the CARDEX (Cloud Aerosol Radiative Forcing and Dynamics Experiment) investigation conducted over the northern Indian Ocean. The UAV and surface data reveal a reduction in turbulent kinetic energy in the surface mixed layer at the base of the atmosphere concurrent with an increase in absorbing black carbon aerosols. Polluted conditions coincide with a warmer and shallower surface mixed layer because of aerosol radiative heating and reduced turbulence. The polluted surface mixed layer was also observed to be more humid with higher relative humidity. Greater humidity enhances cloud development, as evidenced by polluted clouds that penetrate higher above the top of the surface mixed layer. Reduced entrainment of dry air into the surface layer from above the inversion capping the surface mixed layer, due to weaker turbulence, may contribute to higher relative humidity in the surface layer during polluted conditions. Measurements of turbulence are important for studies of aerosol effects on clouds. Moreover, reduced turbulence can exacerbate both the human health impacts of high concentrations of fine particles and conditions favorable for low-visibility fog events.

NGOs, social entrepreneurs, impact investors, and philanthropists need to help slow climate warming., Stanford Social Innovation Review, 11(3), 48-53