Kevin Sieck

Response of Karakoram-Himalayan glaciers to climate variability and climatic change: A regional climate model assessment

The Karakoram and the Himalayan mountain range accommodate a large number of glaciers and are the major source of several perennial rivers downstream. To interactively describe to response of glaciers to climate change, a glacier parameterization scheme has been developed and implemented into the regional climate model REMO. The scheme simulates the mass balance as well as changes of the areal extent of glaciers on a subgrid scale. The parameterization scheme is for the first time applied to the region. A regional glacier inventory is compiled and is used to initialize glacier area and volume. Over the highly complex and data sparse region, the simulated mass balance largely agrees with observations including the positive Karakoram anomaly. The simulated equilibrium line altitude is well captured although a systematic underestimation is apparent. REMO simulates the glacier-climate interaction reasonably well; it has clear potential to be used for future climate assessments.

Case study for the assessment of the biogeophysical effects of a potential afforestation in Europe

BackgroundA regional-scale sensitivity study has been carried out to investigate the climatic effects of forest cover change in Europe. Applying REMO (regional climate model of the Max Planck Institute for Meteorology), the projected temperature and precipitation tendencies have been analysed for summer, based on the results of the A2 IPCC-SRES emission scenario simulation. For the end of the 21st century it has been studied, whether the assumed forest cover increase could reduce the effects of the greenhouse gas concentration change.ResultsBased on the simulation results, biogeophysical effects of the hypothetic potential afforestation may lead to cooler and moister conditions during summer in most parts of the temperate zone. The largest relative effects of forest cover increase can be expected in northern Germany, Poland and Ukraine, which is 15–20% of the climate change signal for temperature and more than 50% for precipitation. In northern Germany and France, potential afforestation may enhance the effects of emission change, resulting in more severe heavy precipitation events. The probability of dry days and warm temperature extremes would decrease.ConclusionsLarge contiguous forest blocks can have distinctive biogeophysical effect on the climate on regional and local scale. In certain regions of the temperate zone, climate change signal due to greenhouse gas emission can be reduced by afforestation due to the dominant evaporative cooling effect during summer. Results of this case study with a hypothetical land cover change can contribute to the assessment of the role of forests in adapting to climate change. Thus they can build an important basis of the future forest policy.

The Role of Forests in Mitigating Climate Change - a Case Study for Europe

Abstract - A regional-scale case study has been carried out to assess the possible climatic benefits of forest cover increase in Europe. For the end of the 21st century (2071-2090) it has been investigated, whether the projected climate change could be reduced assuming potential afforestation of the continent. The magnitude of the biogeophysical effects of enhanced forest cover on temperature and precipitation means and extremes have been analyzed relative to the magnitude of the climate change signal applying the regional climate model REMO. The simulation results indicate that in the largest part of the temperate zone potential afforestation may reduce the projected climate change through cooler and moister conditions, thus could contribute to the mitigation of the projected climate change for the entire summer period. The largest relative effect of forest cover increase can be expected in northern Germany, Poland and Ukraine. Here, the projected precipitation decrease could be fully compensated, the temperature increase could be relieved by up to 0.5 °C, and the probability of extremely warm and dry days could be reduced. Results can help to identify the areas, where forest cover increase could be the most effective from climatic point of view. Thus they can build an important basis of the future adaptation strategies and forest policy. Kivonat - Esettanulmány az erdők klímavédelmi szerepének vizsgálatára Európában. Az esettanulmány célja az erdőterület növekedés éghajlati hatásainak, a klímaváltozás mérsékelésében betöltött szerepének számszerűsítése Európában. A REMO regionális klímamodell segítségével vizsgáltuk, hogy a feltételezett potenciális erdőtelepítéssel milyen irányban és mértékben befolyásolhatók a 2071-2090-es időszakra előrevetített hőmérséklet- és csapadéktendenciák. A modellszimulációk eredményei alapján, potenciális erdőtelepítés feltételezésével nyáron a mérsékelt övi területek döntő része hűvösebb, csapadékosabb lehet. A legnagyobb hatás Németország és Lengyelország északi részén, valamint az ukrán-belorusz-orosz határvidéken várható. Ezeken a területeken az erdőtelepítés hatása a hőmérsékletre egy nagyságrenddel kisebb, mint az üvegházgáz koncentráció változásáé. A klímaváltozással járó csapadékmennyiség-csökkenés azonban szinte teljes egészében kiegyenlíthető lenne, és a szélsőségesen meleg és száraz napok gyakorisága csökkenhet. Az erdő-klíma kölcsönhatások számszerűsítése nem csak az erdők klímavédelmi szerepéről ad információt, hanem az éghajlatváltozás következményeinek megelőzését, enyhítését célzó stratégiák alapja is lehet.

Development of Wet-Bulb-Temperatures in Germany with special regard to conventional thermal Power Plants using Wet Cooling Towers

Wet-bulb-temperature (WBT) def nes the cooling distance of cooling water in wet cooling towers (or wet honeycomb radiators) at water-cooled power plants. Thus, the development of WBT in the 21 century under different scenarios of future climate change is highly relevant for the electricity production sector and is examined in this study for Germany. We use high-resolution simulated data from the regional climate model REMO. As WBT is no direct model output, it is calculated using dry-bulb-temperature (DBT), relative humidity and surface air pressure using two alternative methods. The iterative method provides better results for validation. The computed WBT is quite close to the observations. It reveals a statistically signif cant exponential increase until 2100 ranging from 1.6C to 2.4C in the B1 scenario and from 2.6C to 3.4C in the A2-scenario. Furthermore the study indicates that changes of the DBT will be the decisive factor for the WBT-increase in the 21 century. Signif cant differences in the increase of extreme heat events between a region in northern and one in southwestern Germany are highlighted by a threshold analysis. The increase of hourly extreme values in southwestern Germany is about 30% higher than in the north. A detected west-east gradient is probably related to the North Atlantic Oscillation and a general increase in westerly situations over Germany. The discrepancies between B1 and A2 scenario are striking and highlight the impact of different levels of global greenhouse gas emissions on regional climate.