Identifying and quantifying planetary boundaries that must not be transgressed could help prevent human activities from causing unacceptable environmental change, argue Johan Rockstrom and colleagues.

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A safe operating space for humanity

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.

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Planetary boundaries: Guiding human development on a changing planet

Advances in the science and observation of climate change are providing a clearer understanding of the inherent variability of Earth's climate system and its likely response to human and natural influences. The implications of climate change for the environment and society will depend not only on the response of the Earth system to changes in radiative forcings, but also on how humankind responds through changes in technology, economies, lifestyle and policy. Extensive uncertainties exist in future forcings of and responses to climate change, necessitating the use of scenarios of the future to explore the potential consequences of different response options. To date, such scenarios have not adequately examined crucial possibilities, such as climate change mitigation and adaptation, and have relied on research processes that slowed the exchange of information among physical, biological and social scientists. Here we describe a new process for creating plausible scenarios to investigate some of the most challenging and important questions about climate change confronting the global community.

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The next generation of scenarios for climate change research and assessment

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.

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Planetary boundaries: Exploring the safe operating space for humanity

Investigating soil moisture-climate interactions in a changing climate: A review

The Physical Science Basis

The data set presented represents 15 years of collection. It contains tree-ring width measurements from 64 sites of living trees and ten historical chronologies based on archaeological and construction wood up to year 572 CE, altogether 2909 tree-ring series and more than 450000 measured and cross-dated tree rings. It covers the vast territory of European Russia, including its forested northern and central parts, and the Northern Caucasus mountains. The potential use of these data include climatic reconstructions of regional and hemispheric scale, dendrochronological dating of historical and cultural wood, ecological and remote sensing studies. 

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Tree-ring data set for dendroclimatic reconstructions and dendrochronological dating in European Russia

Contrasting climate signals across a Scots pine (Pinus sylvestris L.) tree-ring network in the Middle Volga (European Russia)

Three paleosols buried in the left lateral moraines of the Greater Azau Glacier (Northern Caucasus) were identified in an excavated outcrop (43.2658 N, 42.4766 E, 2370 m a.s.l.). When the glacier was overlying the surface of the lateral moraines at this site, the thickness of the ice was 50 m and more above the valley floor. Fragments of charcoal from the uppermost soil (S1) buried 0.6 m below the surface yielded the radiocarbon date 130 ± 20 yr BP (IGANAMS-6826) (AD 1680–1939). The middle soil (S2), buried at the depth of 13 m yielded two 14C dates 320 ± 20 yr BP (IGANAMS-8127) (bark of birch) (AD 1496–1641) and 1190 ± 20 yr BP (IGANAMS-8126) (AD 774–889) (charcoal). We suggest that the soil S2 has been formed between these dates during the Medieval Warm Period and in the early Little Ice Age. The lowermost (S3) unit lying 15 m below the surface is the thickest (0.4–0.6 m), well-developed paleosol. Charcoal collected at the top of S3, yielded the date 1300 ± 20 yr BP (IGANAMS-6826) (AD 663–773), indicating a prominent glacier advance occurred shortly before this date. Two dates from the charcoal buried at the bottom of S3 (2855 ± 20 yr BP (IGANAMS-8125) and 2880 ± 20 yr BP (IGANAMS-6827) mark the beginning of a long episode of restricted glacier extent that lasted for about 1600 years. The dates at the bottom of the S3 paleosol constrain the end of glacier advance that occurred before 2800–2900 14C yr BP. The timing of most prominent advances of the Greater Azau Glacier in the past 3500 years is in general agreement with the Late-Holocene glacial chronologies in the European Alps, Scandinavia and other regions of the Northern Hemisphere.

O Solomina

Papers

The Physical Science Basis

Tree-ring data set for dendroclimatic reconstructions and dendrochronological dating in European Russia

Contrasting climate signals across a Scots pine (Pinus sylvestris L.) tree-ring network in the Middle Volga (European Russia)

Late-Holocene advances of the Greater Azau Glacier (Elbrus area, Northern Caucasus) revealed by 14C dating of paleosols

Climate signal strength in tree-ring width of spruce growing in the Solovetsky Islands (Russia)