The carbon-sequestration potential of a global afforestation program

We analyzed the changes in the carbon cycle that could be achieved with a global, largescale afforestation program that is economically, politically, and technically feasible. We estimated that of the areas regarded as suitable for large-scale plantations, only about 345 million ha would actually be available for plantations and agroforestry for the sole purpose of sequestering carbon. The maximum annual rate of carbon fixation (1.48 Gt/yr) would only be achieved 60 years after the establishment of the plantations - 1.14 Gt by above-ground biomass and 0.34 Gt by below-ground biomass. Over the period from 1995 to 2095, a total of 104 Gt of carbon would be sequestered. This is substantially lower than the amount of carbon required to offset current carbon emissions (3.8 Gt/yr) in order to stabilize the carbon content of the atmosphere.     

Climatic Change and Witch-hunting: the Impact of the Little Ice Age on Mentalities

In addition to objective climatic data, subjective or social reactions can also serve as indicators in the assessment of climatic changes. Concerning the Little Ice Age the conception of witchcraft is of enormous importance. Weather-making counts among the traditional abilities of witches. During the late 14^th and 15^th centuries the traditional conception of witchcraft was transformed into the idea of a great conspiracy of witches, to explain "unnatural" climatic phenomena. Because of their dangerous nature, particularly their ability to generate hailstorms, the very idea of witches was the subject of controversial discussion around 1500. The beginnings of meteorology and its emphasis of "natural" reasons in relationship to the development of weather must be seen against the background of this demoniacal discussion. The resurgence of the Little Ice Age revealed the susceptibility of society. Scapegoat reactions may be observed by the early 1560s even though climatologists, thus far, have been of the opinion that the cooling period did not begin until 1565. Despite attempts of containment, such as the calvinistic doctrine of predestination, extended witch-hunts took place at the various peaks of the Little Ice Age because a part of society held the witches directly responsible for the high frequency of climatic anomalies and the impacts thereof. The enormous tensions created in society as a result of the persecution of witches demonstrate how dangerous it is to discuss climatic change under the aspects of morality.     

Present state and future developments of the European geoid

Regional geoid resp. quasigeoid determinations are nowadays required with an accuracy of ±1 to 10 cm over distances from 100 to some 1000 km in order to meet the demands of geodesy, geophysics, oceanography and engineering. Especially the combination of GPS heighting with classical leveling is one of the primary drivers for precise geoid computations. As a consequence, the IAG International Geoid Commission recognized at its meeting in Milano, 1990, that there is an urgent need for a new European geoid computation. This solution should be significantly improved in spatial resolution and accuracy as compared to presently available models. This led to the decision to form a Subcommission for the Geoid in Europe, and the Institut für Erdmessung (IfE) was asked to serve as a computing center in this project.In the first part of this paper early geoid/quasigeoid computations for the area of Europe as well as more recent results obtained at IfE are summarized. The latter solutions include a gravimetric and an astrogravimetric quasigeoid, which have a spatial resolution of about 20 km and a relative accuracy of some dm. Then the possibilities for an improved European quasigeoid calculation are outlined, considering the availability of new and better global and regional data sets. An overview is given on the procedures currently under study at IfE and on the work performed at IfE since 1990. This work includes the collection and screening of new point gravity and terrain data, some investigations on the use of topographic information available at present, and the calculation of a preliminary quasigeoid solution for central, northern and western Europe including a GPS/leveling control. The paper closes with a survey on future activities at IfE within the European geoid project.     

NIZUSE: a deep seismic reflection line in north-eastern Germany

Out of a dense network of seismic reflection lines for hydrocarbon exploration in the North-east German Basin, several lines were recorded to 12 s TWT to obtain information about the structure of the crust and the crust-mantle transition. One of these profiles is presented here. This stretches for 110 km in a NNE direction between Neustrelitz and the island of Usedom. It reaches from the External Variscides in the south across the North German Massif into the Rügen-Pomorze Terrane in the Baltic Sea. Below Cenozoic-Mesozoic-Paleozoic cover with clear reflections down to base Zechstein, the reflectivity varies considerably with depth and also laterally. The Paleozoic and Precambrian sediments and basement are generally void of reflections, but the lower crust and the Moho show strong reflections. To the north the reflectivity decreases, and the Moho depth increases to beyond the bottom of the record section at 12 s. There are no direct indications for deep-reaching faults such as the Trans-European Fault in the north. The North German Massif acted as a ramp towards the Variscan Orogeny, similar to the London-Brabant Massif further west.     

The international decade for natural disaster reduction (IDNDR): A challenge to science

The United Nations proclaimed the 1990s as the International Decade for Natural Disaster Reduction (IDNDR). Based on the ‘Tokyo Declaration’—an action plan for the IDNDR formulated by a commission of highly recognized experts—a program was drafted in March 1991 by the International Scientific and Technical Committee for the IDNDR, whose members were appointed by the Secretary General of the United Nations. Based on this international draft program a framework for national scientific programs should be developed by National Committees. The Decade and its translation into actions are briefly reviewed.