The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth system. Here, we revise and update the planetary boundary framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth system into a new state should they be substantially and persistently transgressed.

/pdf/planetary-boundaries-guiding-human-development-on-a-changing-5gmf909etg.pdf

Planetary boundaries: Guiding human development on a changing planet

TiO2 photocatalysis and related surface phenomena

Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely. Transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental- to planetary-scale systems. We have identified nine planetary boundaries and, drawing upon current scientific understanding, we propose quantifications for seven of them. These seven are climate change (CO2 concentration in the atmosphere <350 ppm and/or a maximum change of +1 W m-2 in radiative forcing); ocean acidification (mean surface seawater saturation state with respect to aragonite ≥ 80% of pre-industrial levels); stratospheric ozone (<5% reduction in O3 concentration from pre-industrial level of 290 Dobson Units); biogeochemical nitrogen (N) cycle (limit industrial and agricultural fixation of N2 to 35 Tg N yr-1) and phosphorus (P) cycle (annual P inflow to oceans not to exceed 10 times the natural background weathering of P); global freshwater use (<4000 km3 yr-1 of consumptive use of runoff resources); land system change (<15% of the ice-free land surface under cropland); and the rate at which biological diversity is lost (annual rate of <10 extinctions per million species). The two additional planetary boundaries for which we have not yet been able to determine a boundary level are chemical pollution and atmospheric aerosol loading. We estimate that humanity has already transgressed three planetary boundaries: for climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. Planetary boundaries are interdependent, because transgressing one may both shift the position of other boundaries or cause them to be transgressed. The social impacts of transgressing boundaries will be a function of the social-ecological resilience of the affected societies. Our proposed boundaries are rough, first estimates only, surrounded by large uncertainties and knowledge gaps. Filling these gaps will require major advancements in Earth System and resilience science. The proposed concept of "planetary boundaries" lays the groundwork for shifting our approach to governance and management, away from the essentially sectoral analyses of limits to growth aimed at minimizing negative externalities, toward the estimation of the safe space for human development. Planetary boundaries define, as it were, the boundaries of the "planetary playing field" for humanity if we want to be sure of avoiding major human-induced environmental change on a global scale.

/pdf/planetary-boundaries-exploring-the-safe-operating-space-for-ir5ysgjg96.pdf

Planetary boundaries: Exploring the safe operating space for humanity

Photoinduced reactivity of titanium dioxide

The global decline in estuarine and coastal ecosystems (ECEs) is affecting a number of critical benefits, or ecosystem services. We review the main ecological services across a variety of ECEs, including marshes, mangroves, nearshore coral reefs, seagrass beds, and sand beaches and dunes. Where possible, we indicate estimates of the key economic values arising from these services, and discuss how the natural variability of ECEs impacts their benefits, the synergistic relationships of ECEs across seascapes, and management implications. Although reliable valuation estimates are beginning to emerge for the key services of some ECEs, such as coral reefs, salt marshes, and mangroves, many of the important benefits of seagrass beds and sand dunes and beaches have not been assessed properly. Even for coral reefs, marshes, and mangroves, important ecological services have yet to be valued reliably, such as cross-ecosystem nutrient transfer (coral reefs), erosion control (marshes), and pollution control (mangroves). An important issue for valuing certain ECE services, such as coastal protection and habitat-fishery linkages, is that the ecological functions underlying these services vary spatially and temporally. Allowing for the connectivity between ECE habitats also may have important implications for assessing the ecological functions underlying key ecosystems services, such coastal protection, control of erosion, and habitat-fishery linkages. Finally, we conclude by suggesting an action plan for protecting and/or enhancing the immediate and longer-term values of ECE services. Because the connectivity of ECEs across land-sea gradients also influences the provision of certain ecosystem services, management of the entire seascape will be necessary to preserve such synergistic effects. Other key elements of an action plan include further ecological and economic collaborative research on valuing ECE services, improving institutional and legal frameworks for management, controlling and regulating destructive economic activities, and developing ecological restoration options.

https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/10-1510.1

The value of estuarine and coastal ecosystem services

Bioreactor Landfill: Cheaper for MSW disposal?

Sustainable Energy and Environmental Technology: Proceedings of the Asia-Pacific Conference

An improved version of a mechanistic mathematical model of anaerobic degradation processes has been developed. It was incorporated into three types of high-rate reactor configuration; namely, single-stage, two-stage, and two-stage with recycle. Implemented in a recently developed simulation package NIMBUS (1) the model was able to simulate the dynamic behaviour of anaerobic wastewater treatment systems. In the present study, the model has been used to predict the system response to a short-term concentration and hydraulic step changes at various volumetric organic loading rates. The comparison between the predicted and the measured data using a synthetic diluted molasses wastewater showed that reactor variables such as pH, alkali consumption rate, gas production and its composition, and effluent organic acids concentration were modelled reasonably well.

The Effect of Concentration and Hydraulic Shock Loads on the Performance of a Two-Stage High-Rate Anaerobic Wastewater Treatment System: Prediction and Validation

Our laboratory has over a period of four years conducted extensive research into the metabolism and batch, fed-batch, continuous, perfusion and serum-free culture of hybridomas with a view to increasing the productivity of these animal cell lines A brief overview of this work and future plans will be presented here In addition an overview of our more limited work on the Baculovirus expression system using insect cell culture, begun during 1989, will also be given

Paul F. Greenfield

Papers

Bioreactor Landfill: Cheaper for MSW disposal?

Sustainable Energy and Environmental Technology: Proceedings of the Asia-Pacific Conference

The Effect of Concentration and Hydraulic Shock Loads on the Performance of a Two-Stage High-Rate Anaerobic Wastewater Treatment System: Prediction and Validation

Studies on hybridoma and insect cells in suspension culture.

Evaluation of reforming catalyst diffusion properties using a batch adsorber