Million years of Greenland Ice Sheet history recorded in ocean sediments

Geological records from Tertiary and Quaternary terrestrial and oceanic sections have documented the presence of ice caps and sea ice covers both in the Southern and the Northern hemispheres since Eocene times, approximately since 45 Ma. In this paper focussing on Greenland we mainly use the occurrences of coarse ice-rafted debris (IRD) in Quaternary and Tertiary ocean sediment cores to conclude on age and origin of the glaciers/ice sheets, which once produced the icebergs transporting this material into the adjacent ocean. Deep-sea sediment cores with their records of ice-rafting from off NE Greenland, Fram Strait and to the south of Greenland suggest the more or less continuous existence of the Greenland ice sheet since 18 Ma, maybe much longer, and hence far beyond the stratigraphic extent of the Greenland ice cores. The timing of onset of glaciation on Greenland and whether it has been glaciated continuously since, are wide open questions of its long-term history. We also urgently need new scientific drilling programs in the waters around Greenland, in particular in the segment of the Arctic Ocean to the north of Greenland

Centennial-scale variability of the British ice sheet: implications for climate forcing and Atlantic meridional overturning circulation during the last deglaciation

Evidence from paleoclimatic archives suggests that Earth's climate experienced rapid temperature changes associated with pronounced interhemispheric asymmetry during the last glacial period. Explanations for these climate excursions have converged on nonlinear interactions between ice sheets and the ocean's thermohaline circulation, but the driving mechanism remains to be identified. Here we use multidecadal marine records of faunal, oxygen isotope, and sediment proxies from the northeast Atlantic proximal to the western margins of the last glacial British Ice Sheet (BIS) to document the coupling between ice sheet dynamics, ocean circulation, and insolation changes. The core data reveal successions of short-lived (80-100 years), high-amplitude ice-rafted debris (IRD) events that were initiated up to 2000 years before the deposition of detrital carbonate during Heinrich events (HE) 1 and 2. Progressive disintegration of the BIS 19-16 kyr before present (B.P.) occurred in response to abrupt ocean-climate warmings that impinged on the northeast Atlantic during the early deglaciation. Peak IRD deposition recurs at 180-220 year intervals plausibly involving repeated breakup of glacial tidewater margins and fringing marine ice shelves. The early deglaciation culminated in a major meltwater pulse at ∼16.3 kyr B.P. followed by another discharge associated with HE1 some 300 years after. We conclude that temperature changes related to external forcing and marine heat transport caused a rapid response of the BIS and possibly other margins of the Eurasian Ice Sheet. Massive but short-lived meltwater surges influenced the Atlantic meridional overturning circulation thereby contributing to North Atlantic climate variability and bipolar climatic asymmetr

Playful participation in social games

Abstract IN THIS PAPER WE INTRODUCE SOCIAL GAMES AS A NEW TERRAIN FOR STUDIES IN PARTICIPATORY CULTURE. SOCIAL GAMES DEFY EASY CLASSIFICATION AND CANNOT BE APPROPRIATELY UNDERSTOOD FROM EXISTING RESEARCH PERSPECTIVES. INITIALLY, WE THEREFORE ATTEMPT TO DEFINE SOCIAL GAMES BY COMPARING THE GENRE WITH RELATED GAME GENRES, NOTABLY SERIOUS GAMES AND HEALTH GAMES. TO FURTHER INCREASE KNOWLEDGE OF SOCIAL GAMES, WE INTRODUCE A TYPOLOGY OF PLAYFUL PARTICIPATION IN SOCIAL GAMES. THE TYPOLOGY IS CONSTRUCTED BY USING FORMAL CONCEPTS FROM THEORIES OF PARTICIPATORY ART. ITS RANGE OF APPLICATION IS THEN DEMONSTRATED THROUGH AN EMPIRICAL ANALYSIS OF EIGHT SOCIAL GAME PROTOTYPES THAT ARE DESIGNED AS PART OF AN ON-GOING THREE-YEAR RESEARCH PROJECT CALLED “SOCIAL GAMES AGAINST CRIME”. THE PURPOSE OF THIS PROJECT IS TO DEVELOP SOCIAL GAMES THAT CAN HELP CHILDREN BUILD RESILIENCE TOWARDS MANY OF THE PERSONAL AND SOCIAL PROBLEMS THEY EXPERIENCE AS A RESULT OF PARENTAL INCARCERATION.</jats:p

Investigations on the Peach 4 Debrite, a Late Pleistocene Mass Movement on the Northwest British Continental Margin

The Peach 4 debrite is the most recent in a series of large scale Pleistocene MTDs within the Barra fan on the northwest British continental margin. Geophysical data indicate that Peach 4 was formed through a combination of blocky and muddy debris flows and affects an area of ~ 700 km2. BGS core sample 56 -10 36, located directly over the Peach 4 debrite, provides a minimum age of 14.68 ka cal BP for the last major failure. An upwards fining turbidite sequence in BGS core sample 56 -10 239 is associ-ated with increased As and S concentrations, indicators of diagenetic pyrite which forms under anoxic conditions. It is proposed that As and S concentrations may pro-vide a method of distinguishing between contourite and turbidite sedimentation, though further research is required

Accelerated drawdown of meridional overturning in the late-glacial Atlantic triggered by transient pre-H event freshwater perturbation

Abrupt decreases of the Atlantic meridional overturning circulation (MOC) during the Late Pleistocene have been directly linked to catastrophic discharges of glacimarine freshwater, triggering disruption of northward marine heat transport and causing global climate changes. Here we provide measurements of excess sedimentary ²³¹Pa/²³⁰Th from a high-accumulation sediment drift deposit in the NE Atlantic that record a sequence of sudden variations in the rate of MOC, associated deep ocean ventilation and surface-ocean climatology. The data series reveal a sequential decrease in the MOC rate at ~18.0 ka BP ago that coincides with only transient and localized freshwater inputs. This change represents a substantial, though not total, cessation in MOC that predates the major Heinrich (H1) meltwater event by at least 1,200 years. These results highlight the potential of targeted freshwater perturbations in promoting substantial MOC changes without a direct linking with catastrophic freshwater surge

4-H Delivery to Homeschool Audiences

4-H Professionals can increase the scope of their program and meet the needs of a growing segment of youth in their community through outreach to homeschoolers. A 4-H Homeschool Program involves coordinating enrichment classes and field trips for homeschool families. 4-H membership has increased by 24% from 2003 to 2005 in Polk County, Oregon, and homeschoolers account for 43% of that increase. The number of 4-H volunteers has increased from the influx of homeschooling parents. This article gives the basics for implementing and delivering programming to homeschoolers, which can increase the overall size and scope of county 4-H programs.4-H Professionals can increase the scope of their program and meet the needs of a growing segment of youth in their community through outreach to homeschoolers. A 4-H Homeschool Program involves coordinating enrichment classes and field trips for homeschool families. 4-H membership has increased by 24% from 2003 to 2005 in Polk County, Oregon, and homeschoolers account for 43% of that increase. The number of 4-H volunteers has increased from the influx of homeschooling parents. This article gives the basics for implementing and delivering programming to homeschoolers, which can increase the overall size and scope of county 4-H programs

Urban experiments exhibited: Exploring practice-based design research and agency in urban space

This article explores the methodological considerations regarding the organization of a site-specific exhibition in urban space and the design research experiments that may be part of such an exhibition. The aim is to encourage design research as ‘exhibition’ and to propose a format that allows theory to enter the exhibition programme for the purpose of aligning exhibition contributions with theoretical contributions. Through the proposed analytical approach, we offer a method and a model to analyse interventions in public space in relation to agency and the participatory agenda for humans and non-humans. The main contribution is an exploration of the specificalities of curating an exhibition in urban space as a distinct practice-based design research project, where programme, research questions and experiments create knowledge on scaling agency in regard to temporality, citizenship and the value of urban space