The development of this
review article has evolved from work carried out by an international
team of the International Space Science Institute (ISSI),
Bern, Switzerland, and from work carried out under the auspices
of Scientific Committee on Solar Terrestrial Physics (SCOSTEP)
Climate and Weather of the Sun‐Earth System (CAWSES‐1).
The support of ISSI in providing workshop and meeting facilities
is acknowledged, especially support from Y. Calisesi and V. Manno.
SCOSTEP is acknowledged for kindly providing financial assistance
to allow the paper to be published under an open access
policy. L.J.G. was supported by the UK Natural Environment
Research Council (NERC) through their National Centre for Atmospheric
Research (NCAS) Climate program. K.M. was supported
by a Marie Curie International Outgoing Fellowship within the
6th European Community Framework Programme. J.L. acknowledges
support by the EU/FP7 program Assessing Climate Impacts
on the Quantity and Quality of Water (ACQWA, 212250) and from
the DFG Project Precipitation in the Past Millennium in Europe
(PRIME) within the Priority Program INTERDYNAMIK. L.H.
acknowledges support from the U.S. NASA Living With a Star
program. G.M. acknowledges support from the Office of Science
(BER), U.S. Department of Energy, Cooperative Agreement
DE‐FC02‐97ER62402, and the National Science Foundation. We
also wish to thank Karin Labitzke and Markus Kunze for supplying
an updated Figure 13, Andrew Heaps for technical support, and
Paul Dickinson for editorial support. Part of the research was
carried out under the SPP CAWSES funded by GFG. J.B. was
financially supported by NCCR Climate–Swiss Climate Research.

/pdf/solar-influences-on-climate-48ynhy9kuz.pdf

Solar influences on climate

. The aim of this paper is to provide the community with a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the last three decades is unprecedented since the maximum extension of the Little Ice Age (LIA, mid-17th–early 18th century). In terms of changes in mass balance, although there have been some sporadic gains on several glaciers, we show that the trend has been quite negative over the past 50 yr, with a mean mass balance deficit for glaciers in the tropical Andes that is slightly more negative than the one computed on a global scale. A break point in the trend appeared in the late 1970s with mean annual mass balance per year decreasing from −0.2 m w.e. in the period 1964–1975 to −0.76 m w.e. in the period 1976–2010. In addition, even if glaciers are currently retreating everywhere in the tropical Andes, it should be noted that this is much more pronounced on small glaciers at low altitudes that do not have a permanent accumulation zone, and which could disappear in the coming years/decades. Monthly mass balance measurements performed in Bolivia, Ecuador and Colombia show that variability of the surface temperature of the Pacific Ocean is the main factor governing variability of the mass balance at the decadal timescale. Precipitation did not display a significant trend in the tropical Andes in the 20th century, and consequently cannot explain the glacier recession. On the other hand, temperature increased at a significant rate of 0.10 °C decade−1 in the last 70 yr. The higher frequency of El Nino events and changes in its spatial and temporal occurrence since the late 1970s together with a warming troposphere over the tropical Andes may thus explain much of the recent dramatic shrinkage of glaciers in this part of the world.

/pdf/current-state-of-glaciers-in-the-tropical-andes-a-multi-4u3jbp6s6n.pdf

Current state of glaciers in the tropical Andes: a multi-century perspective on glacier evolution and climate change

The Mediterranean offers a unique opportunity to study the driving forces of tectonic deformation within a complex mobile belt. Lithospheric dynamics are affected by slab rollback and collision of two large, slowly moving plates, forcing fragments of continental and oceanic lithosphere to interact. This paper reviews the rich and growing set of constraints from geological reconstructions, geodetic data, and crustal and upper mantle heterogeneity imaged by structural seismology. We proceed to discuss a conceptual and quantitative framework for the causes of surface deformation. Exploring existing and newly developed tectonic and numerical geodynamic models, we illustrate the role of mantle convection on surface geology. A coherent picture emerges which can be outlined by two, almost symmetric, upper mantle convection cells. The downwellings are found in the center of the Mediterranean and are associated with the descent of the Tyrrhenian and the Hellenic slabs. During plate convergence, these slabs migrated backward with respect to the Eurasian upper plate, inducing a return flow of the asthenosphere from the backarc regions towards the subduction zones. This flow can be found at large distance from the subduction zones, and is at present expressed in two upwellings beneath Anatolia and eastern Iberia. This convection system provides an explanation for the general pattern of seismic anisotropy in the Mediterranean, first-order Anatolia and Adria microplate kinematics, and may contribute to the high elevation of scarcely deformed areas such as Anatolia and Eastern Iberia. More generally, the Mediterranean is an illustration of how upper mantle, small-scale convection leads to intraplate deformation and complex plate boundary reconfiguration at the westernmost terminus of the Tethyan collision.

Mantle dynamics in the Mediterranean

The western Mediterranean recorded subduction rollback, slab segmentation and separation. Here we address the questions of what caused Oligocene rollback initiation, and how its subsequent evolution split up an originally coherent fore arc into circum-southwest Mediterranean segments. We kinematically reconstruct western Mediterranean geology from subduction initiation to present, using Atlantic plate reconstructions as boundary condition. We test possible reconstructions against remnants of subducted lithosphere imaged by seismic tomography. Transform motion between Africa and Iberia (including the Baleares) between ~120 and 85 Ma was followed by up to 150 km convergence until 30 Ma. Subduction likely initiated along the transform fault that accommodated pre-85 Ma translation. By the ~30 Ma inception of rollback, up to 150 km of convergence had formed a small slab below the Baleares. Iberia was disconnected from Sardinia/Calabria through the North Balearic Transform Zone (NBTZ). Subduction below Sardinia/Calabria was slightly faster than below the Baleares, the difference being accommodated in the Pyrenees. A moving triple junction at the trench-NBTZ intersection formed a subduction transform edge propagator fault between the Baleares and Calabria slab segments. Calabria rolled back eastward, whereas the Baleares slab underwent radial (SW-S-SE) rollback. After Kabylides-Africa collision, the western slab segment retreated toward Gibraltar, here reconstructed as the maximum rollback end-member model, and a Kabylides slab detached from Africa. Opening of a slab window below the NBTZ allowed asthenospheric rise to the base of the fore arc creating high-temperature metamorphism. Western Mediterranean rollback commenced only after sufficient slab-pull was created from 100 to 150 km of slow, forced subduction before ~30 Ma.

/pdf/origin-and-consequences-of-western-mediterranean-subduction-51fwqcz33s.pdf

Origin and consequences of western Mediterranean subduction, rollback, and slab segmentation

Timing of glaciation during the last glacial cycle: evaluating the concept of a global 'Last Glacial Maximum' (LGM)

/pdf/influence-of-upper-mantle-anisotropy-on-isotropic-p-wave-5c9zgnndsg.pdf

Maximiliano Bezada

Papers

Influence of Upper Mantle Anisotropy on Isotropic P-Wave Tomography Images Obtained in the Eastern Mediterranean Region

Late Quaternary deglaciation and Neoglaciation of the Humbloldt Massif, Northern Venezuelan Andes

Paleosols and Andean uplift in Venezuela: assessing competing hypotheses of relict tropical soils versus paleohydrogeochemical variations

Measuring the impact of land degradation on agricultural production: A multi-disciplinery approach

Overlapping slabs: Untangling subduction in NW South America through finite-frequency teleseismic tomography