GC51D-1067 0800h
Simulation of the Last Glacial Inception with the Green McGill Paleoclimate Model
The ``green'' McGill Paleoclimate Model (MPM), which now includes an interactive vegetation component, is run between 122 and 80 kyr Before Present (BP) under variable insolation (Milankovitch forcing) and Vostok-derived atmospheric $CO_2$ concentration (radiative forcing). The model simulates the last glacial inception at around 119 kyr BP, which is followed by the buildup of huge ice sheets over the high northern latitudes, especially North America. Due to the addition of a vegetation component to the MPM, more realistic ice volumes and ice sheet distributions are simulated. In agreement with observations, the ice sheets are smaller over Eurasia and larger over North America. The changes in tree, grass and desert cover during the ice growth phase are also investigated. The results show a southward shift of the treeline and an expansion of the desert at high latitudes, as the ice sheets develop.
GC51D-1068 0800h
The NAO, the AO, and Global Warming: How Closely Related?
The North Atlantic Oscillation (NAO) and closely related Arctic Oscillation (AO) strongly affect Northern Hemisphere (NH) surface temperatures with patterns similar to the global warming trend. The NAO and AO have been in a positive trend for much of the 1970s and 1980s with historic highs in the early 1990s, and it has been suggested that they contribute significantly to the global warming signal. We examine the trends in standard indices of the AO, NAO, and NH average surface temperature for Dec-Feb, 1950 through 2004, and the associated patterns in surface temperature anomalies. We also examine factors previously identified as relating to the NAO, AO, and their positive trend: North Atlantic sea surface temperatures (SSTs), Indo-Pacific warm pool SSTs, stratospheric circulation, and Eurasian snow cover.
GC51D-1069 0800h
Temperature sensitivity and time dependence of the global ocean clathrate reservoir
We assess the impact of anthropogenic warming on the 1-100kyr timescale stability of the methane clathrate reservoir in the oceans. Our assessment is based on model-predicted pCO$_{2}$ and temperature responses to anthropogenic CO$_{2}$ release, coupled to a mechanistic model for the steady-state inventory of clathrate. The model predicts that the steady-state inventory under present-day conditions would contain ~5000 Gton C, and that the steady-state inventory is very sensitive to temperature. Future anthropogenic warming may trigger the release of carbon from the clathrate reservoir, which oxidizes to CO$_{2}$ and contributes to further warming of the deep sea. The strength of this amplifier depends on how quickly the reservoir responds to temperature, because the anthropogenic temperature spike decays with time. The strength of the amplifier also depends on the fraction of methane that escapes from sediments during the meltdown of clathrates. Both of these parameters are still highly uncertain, but plausible values for both predict a global clathrate reservoir which would be unconditionally unstable at the present time, melting down periodically every few million years. If the timescale for meltdown is 10 kyr (conservatively consistent with the Paleocene / Eocene Thermal Maximum event 55 Mya, if that was truly a clathrate carbon release event), then a 50% release fraction is marginally stable. Decomposition of clathrates has the potential to double or triple the anthropogenic perturbation to atmospheric CO$_{2}$ 100 kyr from now. The model predicts glacial / interglacial changes in the methane clathrate reservoir of order 10$^{2}$ Gton C, enough to impact the deglaciation carbon and carbon isotopic budgets.
GC51D-1070 0800h
Stochastic Radiative Transfer in Polar Mixed Phase Clouds
According to recent research, mixed phase clouds comprise one third of the overall annual cloud cover in the Arctic region. These clouds contain distinct regions of liquid water and ice, which have a different impact on radiation than single-phase clouds. Despite the prevalence of mixed phase clouds in the polar regions, many modern atmospheric general circulation models use single-phase clouds in their radiation routines. A stochastic approach to representating the transfer of shortwave radiation through a cloud layer where the distribution of the ice and liquid is governed by observed statistics is being assessed. Data from the Surface Heat Budget of the Arctic (SHEBA) program and the Atmospheric Radiation Measurement (ARM) program's North Slopes of Alaska Cloud and Radiation Testbed site will be used to determine the characteristic features of the cloud field and to evaluate the performance of this statistical model.
GC51D-1071 0800h
Development and Evaluation of a Stochastic Cloud-radiation Parameterization
Previous studies have shown that a stochastic cloud-radiation model accurately represents the domain-averaged shortwave fluxes when compared to observations. Using continuously sampled cloud property observations from the three Atmospheric Radiation Measurement (ARM) Program's Clouds and Radiation Testbed (CART) sites, we run a multiple-layer stochastic model and compare the results to that of the single-layer version of the model used in previous studies. In addition, we compare both to plane parallel model output and independent observations. We will use these results to develop a shortwave cloud-radiation parameterization that will incorporate the influence of the stochastic approach on the calculated radiative fluxes. Initial results using this resulting parameterization in a single-column model will be shown.
GC51D-1072 0800h
Lake Sihailongwan - A Natural Monitor Of Dust Deposition For NE-China. The Pb, Nd, and Sr Isotopic Record.
The dimictic Lake Sihailongwan (SHL, 42$^{o}$17'N, 126$^{o}$25'E) fills a Quaternary volcanic crater. The siliciclastic sediment fraction of Holocene SHL sediments accounts for c. 75 wt-% at 0.3 mm mean annual sediment accumulation and is largely represented by aeolian influx of clay to silt sized debris of remote provenance. The major mineral constituents of the silt are quartz and feldspar. Because of the low influx of solutes, the geochemical signatures of the lacustrine record closely correspond with those of the siliciclastic input. Carbonate, if present in the aeolian input, is not preserved in the local soils and in the Holocene SHL sediments.In the $^{87}$Sr/$^{86}$Sr - $^{143}$Nd/$^{144}$Nd diagram, local alkalibasalts and SHL-sediments define narrow fields that differ from each other. The sediment cluster falls in the variation field of loess and desert sands from North China. The Sr isotope composition of the clay fraction of loess is characterised by a more radiogenic composition than the silt, whereas the Nd isotope characteristics for clay and silt are similar for individual sampling sites. Leaching experiments of loess and sand samples from China demonstrate that the carbonate fraction of loess is characterised by lower $^{87}$Sr/$^{86}$Sr values than the siliciclastic residue. The Sr isotope values of the SHL sediments may be therefore slightly shifted towards higher $^{87}$Sr/$^{86}$Sr values by post depositional carbonate dissolution. Since we have independent evidence for the low concentration of alkalibasaltic debris and the clay/silt balance of the SHL sediments, the mixing trends between the end members (i) alkalibasalt [$^{87}$Sr/$^{86}$Sr= 0.7048, $^{143}$Nd/$^{144}$Nd= 0.51266], (ii) dust-silt, and (iii) dustclay could be used to get a close approximation for the isotopic composition of the dust end members in the SHLsediments: (ii) [$^{87}$Sr/$^{86}$Sr= 0.710, $^{143}$Nd/$^{144}$Nd= 0.51267], (iii) [$^{87}$Sr/$^{86}$Sr= 0.717, $^{143}$Nd/$^{144}$Nd= 0.51268]. The $\epsilon$$_{Nd}$ values for the above end member compositions (-7.2, -7.0) show a close correspondence with the $\epsilon$$_{Nd}$ values of aeolian deposits between 42-43$^{o}$N, 250 to 1000 km west of the lake and are less negative than typical $\epsilon$$_{Nd}$ values of loess or sand samples from the southern Gobi, the Loess Plateau, the Takla Makan desert, and of loess west and north of Beijing. Local alkalibasalts define a mixing trend between $^{206}$Pb($^{208}$Pb)/ $^{204}$Pb= 17.6(38.3) and 18.0(39.0). The SHL sediments plot distinct off this trend with a more radiogenic composition [$^{206}$Pb/$^{204}$Pb= 18.6-18.7, $^{208}$Pb/$^{204}$Pb= 38.8-38.9] close to a narrow field defined by the clay fractions of loess samples from North China. The Pb-concentrations of the silt (16.4 ppm) and clay sized dust influx (30.8 ppm) exceed that of the alkalibasalts (4 ppm). This makes the mixing trend between alkalibasalt Pb and remote Pb less sensitive for minor variations in the influx of alkalibasalt debris. The SHL sediments largely record variations in the Pb isotope signatures of the dust influx. Our data suggest that silt sized dust is characterized by a higher variability in its Pb isotope composition than the clay sized influx. Recent SHL sediments, which record the sedimentation history during the last 50 years, document an increase in the Pb-influx and show a shift to a less radiogenic Pb composition. The Pb isotope composition of soil samples from the vicinity of the lake falls between the trend defined by alkalibasalts and the field defined by the SHL sediments.
http://www.gfz-potsdam.de/pb3/pb33/staff/schet/bilder/LakeSHL.jpg
GC51D-1073 0800h
Primary carbonaceous aerosols and climate modeling: Classifications, global emission inventories, and observations
Carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), make up a large fraction of the atmospheric aerosols and affect the radiative balance of the earth either by directly scattering and absorbing solar radiation or through indirect influence on cloud optical properties and cloud lifetimes. The major sources of BC and OC emissions are from combustion processes, mainly.fossil-fuel burning, biofuels burning, and open biomass burning. OC is nearly always emitted with BC. Because different combustion practices contribute to the emission of BC and OC to the atmosphere, the magnitude and characteristics of carbonaceous aerosols vary between regions. Since OC mainly scatters light and BC absorbs it, it is possible that OC can oppose the warming effect of BC, so that the net climatic effect of carbonaceous aerosols is not known. There is presently disagreement on whether carbonaceous aerosols produce a net warming or cooling effect on climate. Some differences in model prediction may result from model differences, such as dynamics and treatment of cloud feedbacks. However, large differences also result from initial assumptions about the properties of BC and OC: optical properties, size distribution, and interaction with water. Although there are hundreds of different organic species in atmospheric aerosols, with widely varying properties, global climate models to date have treated organics as one compound. In addition, emissions of OC are often derived by multiplying BC emissions by a constant factor, so that the balance between these different compounds is assumed. Addressing these critical model assumptions is a necessary step toward estimating the net climatic impact of carbonaceous aerosols, and different human activities. We aim to contribute to this effort by tabulating important climate-relevant properties of both emissions and ambient measurements. Since one single organic compound is not sufficient to represent all the organics in aerosols, we propose a Climate-Relevant Optical & Structural Subgroups of OC (CROSS-OC) which is a classification for organic aerosols based on structural and optical properties. We provide broad classes aiming at global models instead of very detailed classifications, which are not amenable for use in global-scale models due to the calculation cost. Organic matter (OM) which includes the hydrogen and oxygen bound to this carbon is divided into classes with varied absorption and scattering capabilities. Because our inventory tabulates emissions from specific sources, we make use of data available from source characterization. We present a global emission inventory of primary carbonaceous aerosols that has been designed for global climate modeling purpose. The inventory is based on our CROSS-OC classification and considers emissions from fossil fuels, biofuels, and open biomass burning. Fuel type, combustion type, and emission controls, and their prevalence on a regional basis are combined to determine emission factors for all types of carbonaceous aerosols. We also categorize surface concentration observations for BC and OC by region, size (super vs. sub micron), measurement type, time (including season) and date. We parallel the data format suggested by the Global Atmosphere Watch aerosol database. Work underway includes providing information on the CROSS-OC divisions in ambient aerosol when measurements contain sufficient detail.
GC51D-1074 0800h
Contribution of thermal expansion to present-day sea level rise revisited
In this study, we revisit the contribution of thermal expansion to sea level rise of the last fifty years, comparing two global ocean temperature data sets from Levitus et al. (2000) and Ishii et al. (2003). We apply the method developed by Cabanes et al. (2001) which consists of comparing sea level records of historical tide gauges with thermosteric sea level time series interpolated from the gridded ocean temperature data. First we note that thermosteric sea level trends from Levitus and Ishii data over 1955-1994 agree well at all tide gauges sites considered here except along the coast of northeast US, north of 37°N, where the Levitus thermosteric rates appear overestimated. A similar observation was noticed by Miller and Douglas (2004) based on raw hydrographic data who found the Levitus temperatures abnormally high in the Gulf Stream region. Excluding tide gauges sites from this region (leaving 17 useful sites), we obtain, for the period 1955-1994, mean thermosteric trends of 0.4 +/- 0.3 mm/yr (Levitus data down to 500m and 3000m ) and 0.2 +/- 0.2 mm/yr (Ishii data down to 500m). Such values are more than 3 times lower than the rate of sea level rise computed with tide gauges records, of 1.7 +/- 0.7 mm/yr. This result based on gridded data sets agrees well with that of Miller and Douglas (2004) based on raw hydrographic data. The residual (observed minus thermosteric) rate of sea level rise for 1955-1994 has an average value of 1.4 +/- 0.6 mm/yr. This result confirms recent investigations suggesting a dominant eustatic contribution to last decades mean sea level rise (Antonov et al., 2001, Munk, 2003, Wadhams et al., 2004, Miller and Douglas, 2004).
GC51D-1075 0800h
Climatic Effects on Mammalian Body Size During the African Plio-Pleistocene
Climatic and environmental differences cause geographic patterns of larger versus smaller body sizes (size clines) in certain extant mammals, such as the spotted hyaena (Crocuta crocuta) and the Plains zebra (Equus burchellii). Likewise, body size changes seen in fossil specimens of these taxa from East and southern African Plio-Pleistocene sites are presumed to have climatic and environmental causes. This paper examines body size changes in these two taxa from key fossil sites in East Africa (Olduvai Beds I-IV, East Turkana and Olorgesailie) and southern Africa (Swartkrans, Sterkfontein and Kromdraai) to assess the nature and extent of body size changes. The differences between modern size variation and fossil size variation will be discussed. Results indicate that body sizes of fossil conspecifics in the focal taxa do not follow the pattern of geographic variation seen in modern conspecifics. Climatic and environmental changes may explain these differences, in particular that shifts in the East African region during the Plio-Pleistocene were greater than contemporaneous changes in southern Africa.
GC51D-1076 0800h
Climate Change Affects the East African Rift Valley Lakes
Over the last 100 years, air temperatures in eastern African have been warming consistent with the global average temperature increase. This has led to warmer water temperatures in the East African Rift Valley lakes, increasing the stability of the water column. Subsequently, there has been a reduction in the upwelling of deep nutrient-rich waters that are the primary source of nutrients for most of these lakes. There were decreases in surface water N and P and increases in the Si:P ratio over the past 70 years for Lakes Malawi, Tanganyika, Edward, and Albert. The lower nutrient concentrations in the surface waters were associated with reduced algal biomass and increased water clarity. The consistent, regional-scale changes among these lakes provide strong evidence that climate warming may be having a large negative affect on these unique tropical lakes. A decrease in primary productivity of 20% has been indicated for Lake Tanganyika, which would be associated with a 30% decrease in fisheries yields. The human implications of such subtle, but progressive, environmental changes are potentially dire in this densely populated region of the world, where these large lakes are an important nutritional and economic resource.
GC51D-1077 0800h
Probability Distributions for U.S. Climate Change Using Multi-Model Ensembles
Projections of future climate change vary considerable among different atmosphere ocean general circulation models (AOGCMs) and climate forcing scenarios, and thus understanding of future climate change and its consequences is highly dependent upon the range of models and scenarios taken into consideration. To compensate for this limitation, a number of authors have proposed using multi-model ensembles to develop mean or probabilistic projections of future climate conditions. Here, a simple climate model (MAGICC/SCENGEN) was used to project future seasonal and annual changes in coterminous U.S. temperature and precipitation in 2025, 2050, and 2100 using seven AOGCMs (CSIRO, CSM, ECHM4, GFDL, HADCM2, HADCM3, PCM) and the Intergovernmental Panel on Climate Change's six SRES marker scenarios. Model results were used to calculate cumulative probability distributions for temperature and precipitation changes. Different weighting schemes were applied to the AOGCM results reflecting different assumptions about the relative likelihood of different models and forcing scenarios. EQUAL results were unweighted, while SENS and REA results were weighted by climate sensitivity and model performance, respectively. For each of these assumptions, additional results were also generated using weighted forcing scenarios (SCENARIO), for a total of six probability distributions for each season and time period. Average median temperature and precipitation changes in 2100 among the probability distributions were +$3.4\deg$C (1.6-$6.6\deg$C) and +2.4% (-1.3-10%), respectively. Greater warming was projected for June, July, and August (JJA) relative to other seasons, and modest decreases in precipitation were projected for JJA while modest increases were projected for other seasons. The EQUAL and REA distributions were quite similar, while REA distributions were significantly constrained in comparison. Weighting of forcing scenarios reduced the upper 95% confidence limit for temperature and precipitation changes under the EQUAL and REA distributions, but had little effect on the REA distributions. Although these methods do not represent a completely unbiased sample of possible climate outcomes, multi-model ensembles from simple climate models may be useful for better incorporation of climate uncertainty into impact assessment and other applications.
GC51D-1078 0800h
A Test for Extending the High-Resolution Global Climate Record in Santa Barbara Basin
ODP Site 893 in Santa Barbara Basin recovered high-resolution global climate data extending back to $\sim$160 ka at 200 m sub-seafloor. Safety concerns though have prevented deeper drilling at this site. Santa Barbara Basin is, however, tectonically active. As a result, continuous late-Quaternary strata deposited in the deep paleo-bathymetric basin were uplifted and folded across the Mid-Channel Trend, and strata as old as $\sim$450 ka (OIS 12) appear to be exposed at the seafloor where they are now accessible to piston coring. This project will test the accessibility along the anticline of these older stratigraphic sequences through detailed basin correlation of high-resolution seismic stratigraphy and subsequent coring. In preparation for coring in summer 2005, grids of high-resolution MMS analog, industry multichannel, and 2D USGS high-resolution seismic reflection data (collected in 2002) are being used to correlate dated reference horizons at $\sim$120 ka, $\sim$160 ka and $\sim$1 Ma along with several intervening seismic sequence boundaries across the Mid-Channel Trend. Results provide the basis for modeling the structure and stratigraphy in 3D, and to precisely locate suitable sites for coring. Subsequent core analyses will be used to verify the predicted outcrop pattern and basin-wide sequence stratigraphic interpretation. Thus, in addition to its contributions to Quaternary climate history, this project will help document the nature and evolution of the Mid-Channel anticline, and the local interaction between tectonics, climate, and sea-level change. To date, our results show that the Mid-Channel Trend has propagated from east to west as previously proposed. South of Santa Barbara harbor, folding on the anticline began about 1 Ma, while 10 km farther west, folding began after $\sim$450 ka. Furthermore, our results confirm that older strata (extending back to inferred OIS 12) of the paleo-Santa Barbara Basin have been folded, and are present at or near the seafloor.
GC51D-1079 0800h
Influence of Global Change and Asian Emissions on Regional Air Quality in the Pacific Northwest
Global climate change, land use changes and population growth are interrelated forces that can cause significant changes in future air quality in the US. In the Pacific Northwest, air quality now and in the future can also be exacerbated by the impact of polluted air masses transported from Asia across the Pacific to the US. In this work we address the issue of what role current Asian emissions play on air quality in the Northwest, and how global change might influence the impact of future Asian emissions. To do this we employ a multi-scale numerical modeling system, which is comprised of global scale and nested regional models. On the global scale we employ the NCAR/DOE Parallel Climate Model (PCM) and the NCAR MOZART-2 chemical transport model. The MM5/SMOKE/CMAQ regional modeling system is used to refine the global scale model outputs to regional scale air quality. Global and regional model simulations are conducted for a future period (2045 - 2055) and compared to base case simulations of contemporary climate conditions (1990 - 2000). For contemporary simulations, US anthropogenic emissions are based on the National Emissions trend 1999 (NEI99) dataset, while future year anthropogenic emissions are projected using emission growth factors from EPA's the Economic Growth Analysis System (EGAS) along with IPCC scenarios. Biogenic emissions are treated using the new biogenic emissions Model of Emissions of Gases and Aerosols from Nature (MEGAN). In this paper, we present a preliminary analysis of the results of contemporary, long term simulations in terms of the impact of Asian emissions on Northwest air quality, and we examine the results of MOZART global simulations in terms of changes in boundary conditions for regional simulations in the Northwest for future periods.
GC51D-1080 0800h
Spatiotemporal Analysis on the Long-term Climate Trend in the Twentieth Century
The spatiotemporal signal of the twentieth century long-term climate trend is obtained from the global surface temperature datasets by applying ENSO-removed EOF analysis. The trend mode principle component time series match with the global mean temperature time series. The relative uniform global warming shown in the EOF spatial patterns implies that the global long-term trend should be attributed to relative evenly distributed radiative forcing. And the feature of that stronger warming happens in middle-high latitude land region is consistent with previous linear trend analyses and anthropogenic greenhouse gases model simulations. Several embedded cooling spots that have been related to the anthropogenic sulfate aerosol forcing are also detected in our analysis. Except above previously discovered characters of the 20th century long-term trend, we addressed other characters of the global long-term trend. The most significant one is the mild warming happened in the Pacific basin, comparing to the stronger temperature increase along and beyond the west and east coast of the Pacific Ocean. The changes in the atmospheric parameter fields associated with the long-term trend are also been isolated from the NCEP/NCAR reanalysis dataset. Consistent with the surface temperature zonal contrast caused by the weakened warming in the Pacific Ocean, the main feature of the atmosphere circulation change appears to be a large scale anomalous zonal overturning circulation over the Pacific basin and the surround region, with two ascending wet branches located over the Maritime Continent region and the east Pacific-Amazon region, and one descending dry branch located over the middle Pacific region. This anomalous zonal overturning circulation manifests itself clearer in the middle and upper troposphere than in the lower troposphere, because the atmosphere change in the lower troposphere is affected more by the regional characteristic of the underlying surface. We will also discuss the possible mechanisms behind the weakened warming in the Pacific Ocean and the meaning of this newly disclosed character of the long-term climate change.
GC51D-1081 0800h
Reconstruction of Paleoenvironmental Conditions at the Last Glacial-Interglacial Transition Using Pollen Data From Core MD03-2620 (Cariaco Basin, Caribbean Sea)
The Cariaco Basin, off the coast of Venezuela, acts as a depocenter for sediments of marine and terrestrial origin. The high rate of sedimentation in the basin and the anoxic conditions create a favorable setting for studying short-term paleoenvironmental changes. Pollen analyses of fifty-six samples from core MD03-2620 collected in the basin and spanning the Younger Dryas and Last Glacial/Holocene transition, provide vital information for reconstruction of vegetation dynamic, paleoclimate and sea-level oscillations on the northern margins of South America. Dynamic changes in environmental conditions are clearly reflected in the ratio of arboreal to non-arboreal pollen. The maximum forest vegetation is found at the end of the Last Glacial. Subsequent oscillations in the arboreal to non-arboreal pollen ratio probably represent the Bolling/Allerod. The minimum in forest vegetation occurs at the Younger Dryas, which is followed by a gradual increase in arboreal forms up to Holocene time. Variations in both the diversity of species and the pollen concentration correlate well with the marine oxygen isotope records.
GC51D-1082 0800h
Seasonal Effects on Vegetation Greenness of California Grassland During Five Years of Global Change Treatments
The response of ecosystem net primary production to global environmental changes can vary among ecosystems, across years, and as a result of multi-year feedbacks. To better understand the response of California grassland production to four globally occurring environmental changes, we studied the response of vegetation "greenness" indices, such as the normalized difference vegetation index (NDVI), using a hand-held vis-nir-swir spectrometer during five growing seasons of the Jasper Ridge Global Change Experiment (JRGCE). The JRGCE studies the response of California annual grassland to four global change treatments--warming, nitrogen addition, elevated CO$_{2}$, and increased precipitation--applied in a full-factorial, randomized block design. Across the five years, NDVI followed a characteristic seasonal pattern, rising steeply in the fall at the start of the Mediterranean-type growing season, leveling off or dropping slightly during mid-winter, then rising to an annual maximum in mid-spring, and finally dropping sharply with the onset of summer drought. Each of the global change factors modified this pattern with specific seasonal effects on NDVI. Warming increased NDVI during January and February, except during the one year when these months were unusually warm; warming also tended to decrease NDVI in late spring, indicating accelerated senescence of the vegetation. In all years, watering increased NDVI from the time of peak standing biomass until shortly after two post-season waterings. In addition, during two growing seasons with mid-winter droughts, watering increased NDVI during winter and early spring. In all years, elevated CO$_{2}$ decreased NDVI during late winter and early spring; in some years there was a compensatory increase in NDVI in late spring or early summer. In the spring of each year, added nitrogen increased vegetation greenness, but in alternating years there was also a lag in greening during fall and winter. Seasonally integrated measures of NDVI mirrored interannual changes in the response of aboveground net primary production to the global change treatments.
GC51D-1083 0800h
Recent Active Forest Fires in Boreal Forests and Climate Change
Forest fires in boreal forests are very activated recently. The authors focused on many large forest fires occurred in Alaska and Sakha, East Siberia. The total burnt area of these forest fires of Alaska in 2004 and Sakha in 2002 became historical records. The background of these fires was discussed from the viewpoint of climate change. In 2002, a large number of forest fires occurred near Yakutsk, the eastern part of the Russian Federation. Forest fires started from early May, 2002 and continued until September. In 2004, a large number of forest fires occurred in the interior Alaska. Forest fires started from June, 2004 and also continued even into September. Smoke from these fires not only covered Fairbanks area but also reached east and south coast of main land of the United States of America. The authors approach an investigation of the causes from various angles to establish the causes of the recent abnormal forest fires. Weather conditions such as temperature, rainfall, humidity, wind direction and so on were analyzed by comparing average values. Daily satellite images were processed to show how the forest fires spread in the regions. The results of analysis show how the forest fires near Fairbanks in 2004 and Yakutsk in 2002 were abnormal. The fire phenomenon in boreal forests may be caused by the ongoing global climate change.
GC51D-1084 0800h
Data Modeling, Development, Installation and Operation of the ACEX Offshore Drilling Information System for the Mission Specific Platform Expedition to the Lomonosov Ridge, Arctic Ocean.
During August/September 2004, the Arctic Coring Expedition (ACEX) was used to trial a new Offshore Drilling Information System (OffshoreDIS). ACEX was the first Mission Specific Platform (MSP) expedition of the Integrated Ocean Drilling Programme (IODP), funded by the European Consortium for Ocean Research Drilling (ECORD). The British Geological Survey in conjunction with the University of Bremen and the European Petrophysics Consortium were the ECORD Science Operator (ESO) for ACEX. IODP MSP expeditions have very similar data management requirements and operate in similar working environments to the lake drilling projects conducted by the International Continental Scientific Drilling Program (ICDP), for example, the GLAD800, which has very restricted space on board and operates in difficult conditions. Both organizations require data capture and management systems that are mobile, flexible and that can be deployed quickly on small- to medium-sized drilling platforms for the initial gathering of data, and that can also be deployed onshore in laboratories where the bulk of the scientific work is conducted. ESO, therefore, decided that an adapted version of the existing Drilling Information System (DIS) used by ICDP projects would satisfy its requirements. Based on the existing DIS, an OffshoreDIS has been developed for MSP expeditions. The underlying data model is compatible with IODP(JANUS), the Bremen Core Repository, WDC-MARE/PANGAEA and the LacCore in Minneapolis. According to the specific expedition platform configuration and on-board workflow requirements for the Arctic, this data model, data pumps and user interfaces were adapted for the ACEX-OffshoreDIS. On the drill ship Vidar Viking the cores were catalogued and petrophysically logged using a GeoTek Multi-Sensor Core Logger System, while further initial measurements, lithological descriptions and biostratigraphic investigations were undertaken on the Oden, which provided laboratory facilities for the expedition. Onboard samples were registered in a corresponding sample archive on both vessels. The ACEX-OffshoreDIS used a local area network covering the two ships of the three icebreaker fleet by wireless LAN between the ships and partly wired LAN on the ships. A DIS-server was installed on each ship. These were synchronized by database replication and linked to a total of 10 client systems and label printers across both ships. The ACEX-OffshoreDIS will also be used for the scientific measurement and analysis phase of the expedition during the post-field operations `shore-party' in November 2004 at the Bremen Core Repository (BCR). The data management system employed in the Arctic will be reconfigured and deployed at the BCR. In addition, an eXtended DIS (XDIS) Web interface will be available. This will allow controlled sample distribution (core curation, sub-sampling) as well as sharing of data (registration, upload and download) with other laboratories which will be undertaking additional sampling and analyses. The OffshoreDIS data management system will be of long-term benefit to both IODP and ICDP, being deployed in forthcoming MSP offshore projects, ICDP lake projects and joint IODP-ICDP projects such as the New Jersey Coastal Plain Drilling Project.
http://acex.icdp-online.org
GC51D-1085 0800h
Sealevel, global seismicity and tectonics
Current estimates of secular relative sealevel variations give a uniform rise in the range 1.5-2.0 mm/yr over the last century. The main climatological contributions come from water volume increase due to thermal expansion and water mass increase due to ice melting. The volume increase accounts for a rise of about 0.5 mm/yr while the mass increase is thought to be even smaller. Since earthquakes produce vertical crust displacements and geoid height variations, they change also the relative sea level. On a global scale the combined effect of world seismicity is responsible for a mean relative sealevel variation of 0.1 mm/yr, with a large regional variability. This value is of the same order of magnitude of the climatological contributions and, in sites with strong seismotectonical activity, may represent the dominant contribution of relative sealevel variations measured by tide gauges. The recent measures of sealevel obtained by satellite altimetry show a wide regional variation of sealevel trends over the oceanic surfaces. These measurements, when compared with the global seismic driven signal, show a strong correlation of the geographical distribution of trend signs, while the absolute values of seismic RSL trends are much smaller in magnitude. The physical processes underlying the observed correlation need a deeper analysis to be understood, but we have a strong indication that seismic and tectonic processes plays an important role in the variation of global sealevel.
GC51D-1086 0800h
Simulation of the global warming by the one-dimensional simplified earth system model.
Global warming, resulting from anthropogenic greenhouse gas emissions, is one of the most significant Earth_fs environmental problems. Since global warming is caused by the coupled feedback cycles of energy and carbon, it is essential to assess the impacts of various feedback processes on CO2 uptake by the land and oceans to project future carbon cycle and climate variations. In order to project future changes in carbon cycle and climate, a simple one-dimensional earth system model the carbon and energy coupled cycle model in the simplified manner have been developed. The model consists of a north-south one-dimensional zonally averaged atmosphere-ocean energy balance model, and a box-type one-dimensional carbon cycle model of atmosphere, terrestrial biosphere (vegetation and soil) and ocean, and their interactive feedback processes. The following feedback processes were included in the model, (1) water vapor feedback, (2) biospheric CO2 fertilization, and temperature dependencies on (3) photosynthesis, (4) soil decomposition, (5) ocean surface chemistry. First we simulated the historical variations in temperature and atmospheric CO2 concentration. The model was calibrated to reproduce the past atmospheric CO2 concentration and temperature variations. The past carbon cycle and climatic variations are in good agreement with observational data, but ocean carbon uptake was smaller than the observational result because the south middle latitudinal carbon uptake was small. The future change of carbon cycle and climate was simulated up to the year 2100 based on the IPCC IS92a emission scenario. The atmospheric CO2 concentration reaches 610 ppmv in 2100 and global average temperature increases 1.5 K for 2000-2100. The regional difference of warming between the high and low latitudinal zones is 1.5 K for 2000-2100. The sensitivity analysis showed that uncertainties originated from CO2 emissions by land use, ice albedo feedback and ocean current velocity change were the primary causes of uncertainties in projecting future CO2 concentrations.
GC51D-1087 0800h
Estimates of the Global Inventory of Methane Clathrate: Past, Present and Future
We present a mechanistic model for the distribution of methane clathrate in marine sediments, and use it to predict the sensitivity of the steady-state methane inventory to changes in the deep ocean. The methane inventory is determined by binning the seafloor area according to water depth, temperature, and O$_2$ concentration. Organic carbon rain to the sea floor is treated as a simple function of water depth, and carbon burial for each bin is estimated using a sediment diagenesis model called Muds. The predicted concentration of organic carbon is fed into a clathrate model to calculate steady-state profiles of dissolved, frozen and gaseous methane. We estimate the amount of methane in ocean sediments by multiplying the sediment column inventories by the corresponding binned seafloor areas. Our estimate of the methane inventory is sensitive to the efficiency of methane production from organic matter and to the rate of fluid flow within the sediment column. Preferred values for these parameters are taken from previous studies of both passive and active margins, yielding a global estimate of $3\times10^{18}$ g of carbon (3000 Gton C) in clathrate and $2\times 10^{18}$ g (2000 Gton C) in methane bubbles. The predicted methane inventory decreases by 85% in response to $3^{\circ}$ C of warming. Conversely, the methane inventory increases by a factor of two if the O$_2$ concentration of the deep ocean decreases by 40 $\mu$M or carbon rain increases by 50% (due to an increase in primary production). Changes in sea level have a small effect. We use these sensitivities to assess the past and future state of the methane clathrate reservoir.
GC51D-1088 0800h
Effects of Mean Annual Temperature and Vegetation Type on Soil Carbon Quality in Soils from North America.
Temperature influences belowground carbon cycling, but many uncertainties remain regarding the effects of mean annual temperature (MAT) on soil carbon quality. In particular, it is unclear how temperature alters the physical and chemical protection of organic matter in the more stable soil carbon fraction. The potential of stable carbon to act as a long-term reservoir of carbon is important, but whether storage is sensitive to management or climate is poorly quantified. Here we review data on acid insoluble carbon (AIC), separated from other soil carbon fractions using the established method of acid hydrolysis, and found a negative but non-significant correlation between AIC (soil content or percent of total soil carbon) and MAT (AIC = -MAT x 0.38 + 43; R2 = 0.01; p= 0.59). From the analyses of mean residence time (MRT) of the recalcitrant fraction, we observed that, across the gradient, there is no significant relationship between AIC turnover time and MAT (R2 = 0.08; p = 0.25), although AIC was found to be older at the warmest sites. We explored these relationships more precisely by examining AIC in soils of paired hardwood and Pinus dominated sites across an MAT gradient from Georgia to Colorado, and in parallel samples examining soil C quality through incubation. In this study, MAT across Pinus and hardwood stands ranges between -2 degree C and 20 degree C. Clay content across Pinus stands varied from 1% and 12.3%, with no relationship to MAT, while across hardwood clay content ranged between 2% and 16%, again with no relationship to temperature. Our results will provide information for understanding the relationship between MAT and soil carbon quality.
GC51D-1089 0800h
Sensitivity of Climate Change Diagnostics to Latitude Dependence of Deep-Ocean Heat Uptake
Forest et al. (2002) have presented joint probability density functions (pdfs) for three climate system properties (climate sensitivity (CS) to a doubling of CO2 concentration, effective deep-ocean vertical thermal diffusivity (KV), and the net aerosol forcing (FA)) based on simulations with the MIT 2DLO model. The effective vertical diffusivities used in this model were based on observations of tritium mixing into the deep ocean. As was recently shown by Sun & Hansen (2003, J. Climate), the changes in ocean heat content with depth for the 1951-1998 period differ from the mixing implied by the tritium distribution. The ocean heat content changes show stronger uptake in the tropical and mid-latitude regions as compared to high latitude regions. The goal of this study is to evaluate the sensitivity of temperature change diagnostics used in Forest et al. (2002) to different assumptions regarding the latitudinal distribution of deep-ocean heat uptake. We carried out a number of simulations with the MIT 2DLO model for the 1860-1995 period with a latitudinal profile of the effective vertical diffusion coefficients derived from the Levitus data for ocean heat content changes. The changes in global-mean sea surface air temperature are mainly defined by the global mean value of the effective diffusivities and are not sensitive to the latitudinal dependence. For simulations with CS= 4.0K, KV = 9.0 cm$^2$/s, and FA = -0.5 W/m$^2$, the main effects are seen in the tropical regions where enhanced deep-ocean mixing reduces the surface warming. We will show results of the dependence of the surface, upper-air, and deep ocean temperature diagnostics on CS and FA and discuss the implications for the estimation of the pdfs for the model parameter space: (CS,KV,FA).
http://web.mit.edu/globalchange/www/
GC51D-1090 0800h
Spatio-Temporal Modeling of Vegetational Transboundary Propagation Due to Climate Change
Significant uncertainty is associated with mapping the movement of vegetational zones due climate change. For more accurate mapping of such movements and related impacts on hydrology, a probabilistic approach combined with conceptual hydrologic modeling has been developed. A pattern recognition technique that couples empirical orthogonal functions (EOF), based on Karkhunen-Loeve approach, and a predictor- corrector technique to map vegetational transboundary lines as functions of time and space has been developed. The superiority of the technique lies in its ability to map moisture index isolines, which drive vegetational zones as generated by Monte Carlo simulations. The predictor-corrector method has been incorporated into a monthly water balance model utilizing a Bayesian approach that employs moisture indices derived from remotely sensed imagery and digital elevation information, conditioned by climatic processes. The potential use of this approach in the assessment of streamflow sensitivity to climate change is demonstrated by applications to Western Canadian and Eastern African watersheds. The reliability characteristics of this approach are currently under investigation.
GC51D-1091 0800h
Ocean Warming and Biochemical Effects of Dissociation of Oceanic Methane Hydrates
Ocean exploration during last two decades indicates that huge deposits of oceanic methane hydrate (MH) exist on the seafloor on continental margins. MH transforms into water and methane (CH4) gas when it dissociates. After MH dissociates, CH4 gas is entrapped in bubbles coated with films of microbial. Evidences indicate that a great population of tiny bubbles flows with ocean currents at intermediate depth instead of rising to the ocean surface. This provides the time for microbes (methane oxidation bacteria) to consume the CH4. Earlier observations of CH4 bubbles in swamp and those generated from hydrothermal vents indicate that a great portion of CH4 has been oxidized before the bubbles rise to water surface. The chemical energy (heat) from oxidizing CH4 is released step-by-step following the chemical reactions and transferred from one organism to another through out the food chain. As long as the final products are water and CO2, the total heat to be generated will be conserved in the water mass no matter what processes take place. The energy density is low due to diffusion, but the yield (~195 Kcal/mole of CH4) remains the same. The oxidation of CH4 causes a depletion of dissolved oxygen (O2) in seawater near (and above) MH dissociation level. Ocean observations reflect this biochemical mechanism with a distinct core of minimum dissolved O2 within major ocean currents (like Gulf Stream) flowing over known methane hydrate deposits (like Blake Ridge). The additional heat generated through this micro-biochemical process is sufficient to cause the trend of ocean warming during last 5 decades since the advent of modern ocean observation. The biochemically generated extra heat is carried by Gulf Stream into Arctic Ocean and that complements the atmospheric heat fluxes in thawing the basin's sea ice by the observed thickness. Therefore, it is hypothesized that this micro-biochemical warming of oceans might be one of the factors causing the global warming in the geological past.
GC51D-1092 0800h
Landcover Classification of the Nyack Floodplain Using Remote Sensing and Comparing MultiSpec and ENVI Software
For the past two summer's, I have had two internships studying the Nyack Floodplain south of Glacier National Park in Montana. The internships were with the Flathead Lake Biological Station and with the Landsat Data Continuity Mission at NASA's Goddard Space Flight Center. During the summer of 2003, my internship with the Flathead Lake Biological Station for the biodiversity study to complete a landcover classification of the Nyack floodplain. That same summer my NASA internship was a three-week training course on the basics of Arcview GIS and learning remote sensing using MultiSpec software. That same summer, I used a Trimble GPS backpack unit in the field to collect polygon data of the different landcover types and downloaded the data into Arcview. I also assisted three University of Montana Graduate students with their field research on the same site. During my internships in the summer of 2004, I continued my landcover classification of the Nyack floodplain for the Flathead Lake Biological Station, and I attended a five-week internship at NASA's (Goddard Space Flight Center). During this internship, I continued my landcover classification of the Nyack floodplain. I had two goals for my internships: to identify stressed stands of cottonwood trees along the losing reaches and gaining reaches of the Nyack floodplain using Landsat 7 imagery, and to compare the MultiSpec and ENVI software. The MultiSpec software is a freeware provided through the University of Purdue. This software is very easy to use, with an abundance of tutorials and web pages to make it very user friendly. While the ENVI software is available by purchase. ENVI is a more advanced software that provides more functionality than MultiSpec. Each software did an exceptional job of classifying the Nyack floodplain. I was able to use both MultiSpec and ENVI to classify the landcover types of the Nyack floodplain, but the ENVI program gave me more options and made the supervised classifications easier then the MultiSpec program. A combination of classifications and fieldwork allowed me to locate specific areas on the imagery like the losing and gaining reaches and the cottonwood stands. The cottonwood stand were identified by the use of hyperspectral aerial photographs taken by Dr. F. Richard Hauer of the Flathead Lake Biological Station, and the losing and gaining reaches of the river were identified through research by Dr. Jack A. Stanford of the Flathead Lake Biological Station. Research by Dr. Jack A. Stanford, indicated that the cottonwood stands in the losing reaches of the floodplain were stressed compared to the cottonwood stands in the gaining reaches of the floodplain. This was due to the losing reaches of the floodplain removing nutrients from the substrate of the river, and dispersing them throughout the floodplain through ground water flow paths. While the gaining reaches of the floodplain had less stressed cottonwood stands, due to the nutrients added to these areas from the ground water forced back up into the substrate of the river channel. Using Landsat 7 imagery, MultiSpec software, and ENVI software to identify these areas, I was unable to determine what stands of cottonwood trees were the ones stressed and what ones were not. This is due to the 30-meter pixel size resolution of the Landsat 7 imagery. Higher resolution imagery may be able to identify these stressed stands of cottonwood trees along the losing and gaining reaches of the Nyack floodplain. Since my results came back inconclusive using the Landsat 7 imagery, my next step will be to use higher resolution imagery to see if it can determine these stressed cottonwood stands.
GC51D-1093 0800h
Evidence for a Direct Link Between Solar Variability and Holocene Climate in the Southwest USA
We obtained high-resolution ($<$20 yr sample interval) O and C isotopic data for the past 12,000 years from a well-dated speleothem with continuous growth from the Guadalupe Mountains, New Mexico. The $\delta$$^{18}$O and $\delta$$^{13}$C data show significant variability (-5.81 to -2.66 and 0.35 to -5.26, respectively). At short time scales variations in $\delta$$^{18}$O and $\delta$$^{13}$C are incoherent, while large shifts in both isotopic values are fairly coherent over the period of interest. It is unlikely that changes in $\delta$$^{18}$O and $\delta$$^{13}$C values are driven by kinetic fractionation. Large shifts in $\delta$$^{18}$O and $\delta$$^{13}$C values coincide with changes in other climate proxies such as tree ring data (although these data cover a short period) and speleothem gray scale data. Summer moisture is primarily derived from the Gulf of Mexico, while isotopically lighter Pacific moisture dominates winter precipitation. Stable isotope variations in our speleothem likely reflect variability in the amount of precipitation and/or balance in moisture source. The most salient feature of our stable isotopic data, and especially the $\delta$$^{18}$O data, is that shifts in isotopic values at centennial time-scales strongly coincide with shifts in the $\Delta$$^{14}$C values. Variations in $\Delta$$^{14}$C values are thought to reflect changes in solar activity and intensity. Residuals of the detrended $\delta$$^{18}$O and $\Delta$$^{14}$C values are negatively correlated. The excellent visual match is supported by preliminary results from cross correlation and spectral analyses. The strong coherence between the stable isotope data and the $\Delta$$^{14}$C data suggests solar forcing may play a role in continental climate variability at centennial to millennial time scales. The forcing may not be necessarily direct however, given the inferred magnitudes in solar variability over the past 12,000 years are not large.
GC51D-1094 0800h
Clearing the Air: Challenges and Successes in Overcoming Confusion about Climate Change
Summarized are experiences with a variety of audiences, such as public events and radio talk shows as well as in coordinating panel presentations at four annual Environmental Law Conference and in presenting to students. In particular the usefulness is explained of clarifying that, while scientists differ regarding particular possible climate dynamics and scenarios, there is no scientific controversy about the Greenhouse Effect. Also successes in making the distinction between the greenhouse effect and the enhanced greenhouse effect are described. Asking audiences the question "Approximately how much carbon (not "carbon dioxide") is added to the atmosphere when one gallon of gasoline is burned?" (answer, approximately 5 pounds) has proven to be an effective way to help people to understand and relate their personal experience to larger aggregate measures of carbon emissions. Other issues regarding differences in how much people discount the future and the implications of these differences for support for climate and energy policies are discussed.
GC51D-1095 0800h
Subsurface thermal effects of deforestation and borehole climatology
Changes in land surface conditions such as deforestation or forest fires modify the energy balance at the ground surface. Such energy imbalances appear as subsurface transient thermal signals superimposed on the climatic signal and the steady state geothermal field. Removal of the forest canopy increases the solar radiation reaching the ground surface. The associated increase in albedo is compensated by a decrease in evapotranspiration and the ground gains energy causing the surface temperature to increase. In the context of the ground surface energy balance and the thermal regime of the subsurface, the forest floor organic matter layer acts as a thermal insulator and moisture-retaining layer covering the ground. The integrated transient thermal signals caused by the rearrangement of the energy budget at the air-ground interface and by the variation of forest floor organic matter layer after deforestation are propagated and recorded in the subsurface. In this study, we examine the effects of deforestation on borehole temperature data by applying a first-order correction method to the subsurface data. We simulate the ground surface temperature variation following deforestation using a combined power and exponential function, based on data obtained from a chronosequence study of the evolution of forest floor organic matter mass. We show that the effects of deforestation on the subsurface temperatures, though important, are much smaller than previously thought. The application of this correction to the borehole temperature data from areas affected by land use changes may allow their incorporation into climatological studies.
GC51D-1096 0800h
Assessing Benefits and Costs of Adaptive and Mitigative Strategies for Climate in Urban Areas
Over the next five decades, climate change is projected to have adverse impacts on human health in temperate regions such as North America. Urban areas within temperate regions may warm disproportionately compared to tropical and subtropical zones according to the IPCC Special Report on The Regional Impacts of Climate Change, and the frequency of very hot days in these climates is expected to approximately double for an increase of 2-3°C in the average summer temperature. Interventions in the built environment to promote urban heat island mitigation can reduce ambient temperatures, potentially reducing heat-related mortality rates in vulnerable populations, electricity consumption and air pollutant emissions, and slow ozone formation, an important health stressor. These mitigation measures may also serve as adaptive responses to a range of potential future climate conditions. We review studies that attempt to quantify health and environmental benefits in US cities from these interventions in the built environment, and discuss the techniques and potential benefits of measures that may serve as both adaptive responses to current conditions and mitigation for potential future increased climate variability.
GC51D-1097 0800h
Integrated Assessment of Climate Variability and Change in the Tropical Peruvian Andes
Considering that the intensity and frequency of recurrent extreme events associated with flooding, droughts and freezes observed in the tropical Peruvian Andes could change with future global warming, an effort has begun to: (1) investigate the causes of such extreme events using correlation and principal component analysis; (2) generate future climate scenarios using statistical and dynamical downscaling; (3) integrate with the studies of vulnerability and adaptation strategies in the region. The purpose of this paper is to describe the results of this effort, which is part of the national plan to strengthen the capacity to manage the impacts of climate change.