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

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

/pdf/climate-change-2007-the-physical-science-basis-1x93ttz9jt.pdf

Climate Change 2007: The Physical Science Basis.

[1] EGM2008 is a spherical harmonic model of the Earth's gravitational potential, developed by a least squares combination of the ITG-GRACE03S gravitational model and its associated error covariance matrix, with the gravitational information obtained from a global set of area-mean free-air gravity anomalies defined on a 5 arc-minute equiangular grid This grid was formed by merging terrestrial, altimetry-derived, and airborne gravity data Over areas where only lower resolution gravity data were available, their spectral content was supplemented with gravitational information implied by the topography EGM2008 is complete to degree and order 2159, and contains additional coefficients up to degree 2190 and order 2159 Over areas covered with high quality gravity data, the discrepancies between EGM2008 geoid undulations and independent GPS/Leveling values are on the order of ±5 to ±10 cm EGM2008 vertical deflections over USA and Australia are within ±11 to ±13 arc-seconds of independent astrogeodetic values These results indicate that EGM2008 performs comparably with contemporary detailed regional geoid models EGM2008 performs equally well with other GRACE-based gravitational models in orbit computations Over EGM96, EGM2008 represents improvement by a factor of six in resolution, and by factors of three to six in accuracy, depending on gravitational quantity and geographic area EGM2008 represents a milestone and a new paradigm in global gravity field modeling, by demonstrating for the first time ever, that given accurate and detailed gravimetric data, asingle global model may satisfy the requirements of a very wide range of applications

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2011JB008916

The development and evaluation of the Earth Gravitational Model 2008 (EGM2008)

This chapter addresses changes in weather and climate events relevant to extreme impacts and disasters. An extreme (weather or climate) event is generally defined as the occurrence of a value of a weather or climate variable above (or below) a threshold value near the upper (or lower) ends (‘tails’) of the range of observed values of the variable. Some climate extremes (e.g., droughts, floods) may be the result of an accumulation of weather or climate events that are, individually, not extreme themselves (though their accumulation is extreme). As well, weather or climate events, even if not extreme in a statistical sense, can still lead to extreme conditions or impacts, either by crossing a critical threshold in a social, ecological, or physical system, or by occurring simultaneously with other events. A weather system such as a tropical cyclone can have an extreme impact, depending on where and when it approaches landfall, even if the specific cyclone is not extreme relative to other tropical cyclones. Conversely, not all extremes necessarily lead to serious impacts. [3.1] Many weather and climate extremes are the result of natural climate variability (including phenomena such as El Nino), and natural decadal or multi-decadal variations in the climate provide the backdrop for anthropogenic climate changes. Even if there were no anthropogenic changes in climate, a wide variety of natural weather and climate extremes would still occur. [3.1] A changing climate leads to changes in the frequency, intensity, spatial extent, duration, and timing of weather and climate extremes, and can result in unprecedented extremes. Changes in extremes can also be directly related to changes in mean climate, because mean future conditions in some variables are projected to lie within the tails of present-day conditions. Nevertheless, changes in extremes of a climate or weather variable are not always related in a simple way to changes in the mean of the same variable, and in some cases can be of opposite sign to a change in the mean of the variable. Changes in phenomena such as the El Nino-Southern Oscillation or monsoons could affect the frequency and intensity of extremes in several regions simultaneously.

/pdf/changes-in-climate-extremes-and-their-impacts-on-the-natural-1fikyoq21o.pdf

Changes in climate extremes and their impacts on the natural physical environment.

Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6-9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics-including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs-that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.

Contribution of Antarctica to past and future sea-level rise

This paper reviews various aspects of the direct method in airborne gravimetry, using a strapdown inertial measurement unit (IMU) and GNSS. The direct method (also referred to as “accelerometry approach” or “cascaded approach”) is a cascaded two-step approach: inertial accelerations are computed from GNSS positions using numerical differentiation in the first step, which are then removed from IMU specific force measurements in the second step. The transformation of strapdown measurements into the navigation frame requires the knowledge of the vehicle’s attitude, which is commonly computed using a commercial IMU/GNSS strapdown navigation software. In contrast, the indirect method (also referred to as “inertial navigation approach” or “one-step approach”) combines all available measurements (GNSS positions and IMU measurements) in a single Kalman-Filter, which is, however, more difficult to implement and requires a substantial tuning of the filter. A comparison of both approaches based on real campaign data indicates the overall quality of the two approaches being on a par. The accuracy achieved is 0.6 mGal (after line adjustment) and 1.3 mGal (without adjustment) at flight altitude, with a spatial resolution of about 6 km (half-wavelength). These results demonstrate for the first time that both processing approaches can achieve gravity disturbances at the same level of accuracy. This paper discusses the fundamentals of the direct method, addressing readers who are striving for their own implementation. The various corrections and data processing aspects are presented in detail as well as a standard evaluation scheme.

The Direct Method in Strapdown Airborne Gravimetry - a Review. submitted.

CryoVEx 2011-12 Airborne Campaigns for CryoSat Validation

Surface Elevation Changes Of The Greenland Ice Sheet- Results From ESA's Ice Sheet CCI

Gravity and Geoid.- Developments in static and kinematic gravimetry Convenor.- The changing role of gravity reference networks.- Improving accuracy and reliability of airborne gravimetry by multiple system configurations.- Combining airborne and ground gravity using collocation.- Comparisons between absolute (AG) and superconducting (SG) gravimeters.- An airborne geoid mapping system for regional sea-surface topography: application to the Skagerrak and Azores areas.- The German gravity base net 1994 (DSGN 1994).- SAR Interferometry for improved terrain corrections in surface and airborne gravimetry.- National gravimetric network of Uruguay.- Global gravity field from gravimetry and satellite altimetry Convenors.- Past and future developments in geopotential modelling.- The world of gravity according to Rapp.- Gravity field improvement activities at NASA GSFC.- The development by the National Imagery and Mapping Agency of a global surface gravity anomaly database for the EGM96 geopotential model and future applications.- On the possibility to estimate ocean bottom topography from marine gravity and satellite altimeter data using collocation.- Generating orthometric heights from the ERS-1 altimeter geodetic mission dataset: results from an expert systems approach.- Use of ERS-1 land altimetry to validate the Globe global digital elevation model.- Geodetic application of ERS-1 altimeter data over land.- Global marine gravity and mean sea surface from multimission satellite altimetry.- Sea level variations measured by TOPEX/POSEIDON and by tide gauges: a validation study in the southern Baltic Sea.- Observed inconsistencies between satellite-only and surface gravity-only geopotential models.- A comparison of satellite altimetry methods for the recovery of gravity field quantities.- Gravity determination in ice covered regions by altimetry.- The geoid - theory and methods Convenor.- A priori estimates of the solution of the geodetic boundary value problem.- Application of multiresolution filtering in geoid determination.- Geoid computation by collocation in scaling spaces.- An efficient technique for the computation of the gravimetric quantities from geopotential earth models.- Modified kernels in spectral geoid determination - first results from Western Australia.- Geoids and cap sizes.- The effects of varying cap sizes on geoid computations - experiences with FFT and ring integration.- A comparison of techniques for the integration of satellite altimeter and surface gravity data for geoid determination.- Application of spherical wavelets for regional gravity field recovery - a comparative study.- Comments on two dimensional convolutions of the geodetic problems in planar and spherical coordinates.- Overdetermined gravity gradiometry boundary value problem: theory and simulation.- Investigations on the earth's relativistic gravity field.- Geoid and mass density - why and how?.- Operational merging of satellite, airborne and surface gravity data by draping techniques.- Regional geoids and the gravity field of South America Convenors.- The European gravimetric quasigeoid EGG97 - an IAG supported continental enterprise.- A preliminary geoid model for Argentina.- The gravimetric geoid in Algeria: first results.- Geoid studies in the north-east Atlantic (Azores-Portugal).- The gravimetric geoid for Libya.- Comparison between altimetric and gravimetric geoid in the south-west Meditterranean basin.- Data, processing for a geoid model in Argentina.- Decimetric geoid for Buenos Aires province based on GPS and global models.- Towards a regional geoid determination in western Venezuela.- Improved gravimetric geoid AGG97 of Austria.- Geodynamics.- Earth rotation and variations of the geopotential Convenors.- Metrology of the Earth's rotation over 1988-1997.- Earth orientation parameter analysis from VLBI data.- Tempo: determining, combining, and predicting earth orientation parameters for space craft navigation.- Possible temporal variations of the free core nutation and forced nutations.- Excitation of nutation as deduced from results of the recent atmospheric reanalysis project.- Regional atmospheric angular momentum contributions to the polar motion excitation.- Time-frequency characteristics of the pressure term of the EAAM excitation functions in some geographic regions.- The spacetime gravitational field of a deformable body.- Temporal variation of the geopotential: processes and interactions among the Earth's subsystems.- Monitoring geoidal potential on the basis of Topex/Poseidon altimeter data and EGM96.- Reference frames and global deformations Convenor.- Absolute positioning, tectonic plate motions and polar motion determination with the DORIS system.- Geodetic baseline adjustment by VLBI technique.- Adjustment of a European combined GPS-SLR-VLBI fundamental network.- Combination of VLBI, SLR and GPS determined station velocities for actual plate kinematic and crustal deformation models.- Geodesy demonstration experiment (GEDEX) for space VLBI: state of the art and software development.- An integrated crustal movement monitoring network in China.- VLBI, SLR and GPS observations in the Key Stone Project.- Cooperation of the sixteen CEI (Central European Initiative) countries in geodesy and geodynamics.- No relative movements between South America and Scotia plates in Tierra del Fuego.- A numerical model for the study of the load effect of the water in the area of the river Plate.- Crustal deformation along the Caribbean-South American plate boundary derived from the CASA GPS project.- The Aqaba earthquake of November 22, 1995 and co-seismic deformation in Sinai Peninsula, deduced from repeated GPS measurements.- Fault model of the 1995 north Sakhalin earthquake based on SAR interferogram.- Integration of GPS Algerian sites in west Mediterranean geodynamical studies - case of TYRGEONET project.- Combination of space observations with other observations of deformations Convenors.- Multi-parametric experiment for observing crustal deformations in southern Brazil.- The determination of motion rates of blocks in Qinghai-Tibet plateau by GPS measurements.- Detection of crustal deformations by SAR interferometry in combination with dense GPS array.- Modelling vertical crustal deformation in time and position domains, inferred from GPS levelling.- Comparison of crustal deformations observed with GPS and strainmeters/tiltmeters.- Present-day kinematics of central Asia derived by joint inversion of geological and geodetic data.- Application of the anomaly of astrometric observations to earthquke prediction study.- Interdisciplinary studies of astronomical factors and earthquakes in China.- Geodesy in Antarctica.- Geodesy in Antarctica Convenor.- The ice-age geodynamics of Antarctica.- Elevation changes in Antarctica 1992-1996: implications for ice sheet mass balances.- The SCAR GPS campaigns: accurate geodetic reference in Antarctica.- Uruguayan contribution to the Antarctic geodesy.- GPS for ice sheet movement monitoring and grounding line detection.- Comparison of altimetric and shipborne marine gravity over ice-free and ice-covered polar seas.- Italian geodetic network as reference frame for geodynamics purposes (Terra Nova Bay - Victoria Land - Antarctica).- Ice-ocean-solid earth interactions in Dronning Maud Land/Antarctica: a geodetic approach to solve open questions.- The contribution of the geodetic observatory O'Higgins to the realization of a geodetic reference frame in Antarctica.- Towards a new free air anomaly map of the Antarctic Peninsula.- Regional geoid improvement based on surface gravity data.- SAR data acquisitions at Syowa station in Antarctica.- Crustal uplift around Syowa station, Antarctica.- Geodetical and geophysical observations at Syowa station, Antarctica.- Author Index.

Geodesy on the move : gravity, geoid, geodynamics and Antarctica : IAG Scientific Assembly, Rio de Janeiro, Brazil, September 3-9, 1997

OSGM02: A Geoid Model of the Britisk Isles: Stage Two (Final) Report

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