Strengths and weaknesses of the Net-Map tool for participatory social network analysis in resource management: Experience from case studies conducted on four continents

For researchers, conducting face-to-face interviews is always a challenge as it often turns into a one-way directed information retrieval. Therefore, interviewees not always are very motivated, enthusiastic and cooperative in responding to the questions. In the end, this has implications for the quality of the interview data. To improve the interview setting and the resulting data, in several projects the Net-Map tool was used to conduct participatory social network analysis. The tool is a combination of in-depth interviews and participatory network mapping. During the interviews, the interviewee draws the network of relevant actors, notes down their motivations and evaluates and displays the actors’ influence and benefits by building towers using any kind of stacks. In this research note, we present the strengths and weaknesses of the method against the experiences with applying the Net-Map tool on four different continents and give ideas for improvements and further research.Peer Reviewe

Transient simulation of the last glacial inception. Part II: sensitivity and feedback analysis

Abstract The sensitivity of the last glacial-inception (around 115 kyr BP, 115,000 years before present) to different feedback mechanisms has been analysed by using the Earth system model of intermediate complexity CLIMBER-2. CLIMBER-2 includes dynamic modules of the atmosphere, ocean, terrestrial biosphere and inland ice, the last of which was added recently by utilising the three-dimensonal polythermal ice-sheet model SICOPOLIS. We performed a set of transient experiments starting at the middle of the Eemiam interglacial and ran the model for 26,000 years with time-dependent orbital forcing and observed changes in atmospheric CO 2 concentration (CO 2 forcing). The role of vegetation and ocean feedback, CO 2 forcing, mineral dust, thermohaline circulation and orbital insolation were closely investigated. In our model, glacial inception, as a bifurcation in the climate system, appears in nearly all sensitivity runs including a run with constant atmospheric CO 2 concentration of 280 ppmv, a typical interglacial value, and simulations with prescribed present-day sea-surface temperatures or vegetation cover-although the rate of the growth of ice-sheets growth is smaller than in the case of the fully interactive model. Only if we run the fully interactive model with constant present-day insolation and apply present-day CO 2 forcing does no glacial inception appear at all. This implies that, within our model, the orbital forcing alone is sufficient to trigger the interglacial-glacial transition, while vegetation, ocean and atmospheric CO 2 concentration only provide additional, although important, positive feedbacks. In addition, we found that possible reorganisations of the thermohaline circulation influence the distribution of inland ice

Simulation of the global bio-geophysical interactions during the Last Glacial Maximum.

The bio-geophysical feedbacks during the Last Glacial Maximum (LGM, 21 000 y BP) are investigated by use of an asynchronously coupled global atmosphere-biome model. It is found that the coupled model improves on the results of an atmosphere-only model especially for the Siberian region, where the inclusion of vegetation-snow-albedo interaction leads to a better agreement with geological reconstructions. Furthermore, it is shown that two stable solutions of the coupled model are possible under LGM boundary conditions. The presence of bright sand desert at the beginning of a simulation leads to more extensive subtropical deserts, whereas an initial global vegetation cover with forest, steppe, or dark desert results in a northward spread of vegetation of up to some 1000 km, mainly in the western Sahara. These differences can be explained in the framework of Charney's theory of a "self-induction" of deserts through albedo enhancement. Moreover, it is found that the tropical easterly jet is strengthened in the case of the "green" Sahara, which in turn leads to a modification of the Indian summer monsoon

Climate change in northern Africa: The past is not the future

By using a climate system model of intermediate complexity, we have simulated long-term natural climate changes occurring over the last 9000 years. The paleo-simulations in which the model is driven by orbital forcing only, i.e., by changes in insolation caused by changes in the Earth's orbit, are compared with sensitivity simulations in which various scenarios of increasing atmospheric CO2 concentration are prescribed. Focussing on climate and vegetation change in northern Africa, we recapture the strong greening of the Sahara in the early and mid-Holocene (some 9000-6000 years ago), and we show that some expansion of grassland into the Sahara is theoretically possible, if the atmospheric CO2 concentration increases well above pre-industrial values and if vegetation growth is not disturbed. Depending on the rate of CO2 increase, vegetation migration into the Sahara can be rapid, up to 1/10th of the Saharan area per decade, but Could not exceed a coverage of 45%. In our model, vegetation expansion into today's Sahara is triggered by an increase in summer precipitation which is amplified by a positive feedback between vegetation and precipitation. This is valid for simulations with orbital forcing and greenhouse-gas forcing. However, we argue that the mid-Holocene climate optimum some 9000 to 6000 years ago with its marked reduction of deserts in northern Africa is not a direct analogue for future greenhouse-gas induced climate change, as previously hypothesized. Not only does the global pattern of climate change differ between the mid-Holocene model experiments and the greenhouse-gas sensitivity experiments, but the relative role of mechanisms which lead to a reduction of the Sahara also changes. Moreover, the amplitude of simulated vegetation cover changes in northern Africa is less than is estimated for mid-Holocene climate