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PI: K. Gajewski - Département de géographie, Université d'Ottawa |
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Co-PI: P. Richard - Département de géographie, Université de Montréal |
The goal of CSHD Project 4 is the reconstruction of past climates and the analysis of the climate change from the fossil record. This project is synthesis of existing data, development of new quantitative methods for climate reconstruction and the generation of key data of terrestrial paleoclimates.
The analyses are being done on a nested hierarchy of spatial scales, which are determined in part by available data and potential for significant new syntheses and results, as well as potential for collaboration with international efforts. The areas are: (a) The St Lawrence Valley, (b) Québec, (c) Eastern Canada arctic and Greenland, (d) North America, (e) Global. During the first period of the project, work was primarily concerned with the Holocene time-scale. This will continue in the second grant period, however more work will be done on another PAGES time-scale - the last 2000 years.
ACHIEVEMENTS ||| Top |||
St Lawrence Valley: M. Lavoie is in the final stages of writing his doctoral thesis on Holocene paleohydrological changes in southern Québec based on peatland development and lake-level changes. Results are important to constrain precipitation and evapotranspiration reconstructions based on other methods.
A new project, a collaboration between U Montréal and U Ottawa, is made possible due to dense array of sites, developed by Richard during more than 20 years of research, in this region (CSHD papers 4-2, 4-4, 4-7). M. Sawada is currently writing his thesis proposal on this subject, which will be described below (Proposed Activities). We are developing the database needed for this project, and this should be available shortly.
(b) Québec: The objectives of this project are to better document and understand the postglacial environmental history, emphasising hydrological and associated phenomena such as fire. Syntheses of the paleoenvironmental conditions of Québec have been published (CSHD papers 4-3, 4-6). An additional project of paleohydrological reconstructions based on lake-level changes has been developed for the Abitibi region (M. Savard, Ph.D.) and the Gaspé Peninsula (H. Asnong, M.Sc.) along with vegetational reconstructions (CSHD paper 4-4, 4-5). A new deglaciation chronology provides revised boundary conditions for climate models (CSHD paper 4-12).
Charcoal analysis is progressing in sites from several regions including the Gaspé Peninsula and Abitibi (CSHD papers 4-9, 4-11). In addition to fire incidence (background charcoal), fire chronologies (fire frequency) are being developed through high-resolution contiguous analyses of lake sediment cores and linked to the Canadian Fire Weather Index (M. Flannigan, Forestry Canada). Since fire incidence is related to climate, this should help us to improve our climate reconstructions. These data can be used by glaciologists, who are estimating fire occurrence in eastern North America from tracers in Greenland ice cores. The interpretation of these tracers is not clear, and having good calibration data for such a large area as Québec will help in the interpretation.
(c) Eastern Canada arctic and Greenland: Accomplishments during this grant period include completion of a collaborative study between Project 4 and Project 2 comparing marine and terrestrial climate reconstructions of eastern Canada (CSHD paper 4-14). Pollen analyses in the marine cores by deVernal and associates provided the link to the terrestrial pollen sequences. This study is the first step in our goal of a data-model comparison of the North American - North Atlantic - European sectors, which is planned for the coming grant period.
Several issues arose during the course of the North American climate reconstruction, described in (d) below. One is the lack of modern pollen data in northern North America (CSHD paper 4-8), making the paleoclimate estimates less reliable. The generation of new data is the focus of Gajewski's NSERC Science Grant, but little money is available for the analysis after field and lab expenses. M. Frappier was hired to speed along the generation of new data. Progress was made, but was slowed by the extremely low pollen concentrations encountered in the samples.
Atkinson's Ph.D. thesis, partly supported by this project, provides new modern climate data with higher spatial resolution for the arctic. He is estimating the mesoclimate of the arctic using two approaches: (a) the development and analysis of a database of non-standard summer climate measurements (PCSP archive) and (b) development of a GIS-based model of mesoscale climate. These are needed for pollen-climate calibration that will be done in the next grant period. As well, these high-resolution modern data will be publicly distributed and can be used by the scientific community working in northern Canada.
As part of the collaboration with project CSHD Project 6, J. Bourgeois, a GSC researcher, has nearly finished her Ph.D. with Gajewski (CSHD paper 4-1). She is investigating pollen in ice cores as indicators of past climates, and investigating the modern transport of pollen in the arctic. In addition to tracing the transport of pollutants in the arctic this information aids in the interpretation of pollen diagrams in the arctic.
We have developed a new climate proxy indicator in the arctic – varve thickness measurements in a lake from Devon Island (CSHD paper 4-10). These data have already been incorporated into a synthesis publication (CSHD paper 4-13).
As part of the international collaboration with PALE (G. Miller), two high-resolution pollen diagrams from Baffin, one 12, 000 years old and the other dating to the last interglacial have been produced by Richard’s team. Results will soon be published in co-operation with A. Wolfe (INSTAAR; ex-postdoc with Richard)
(d) North America: A first accomplishment was to integrate the Canadian pollen database (developed by Gajewski) with the North American Database (Grimm, Illinois Museum) to perform a North American-scale climate reconstruction for the Holocene. By the end of the first grant period, the Canadian database will be sent to Illlinois, to be made public and fill in several gaps in the available coverage. Still to be integrated is a Greenland pollen database, and this will be a goal of the renewal.
A major effort was made to create a map of Holocene climates for North America (Soroko MA thesis). A 6ka map has been finished (Soroko & Gajewski, 1997, presentation at Banff conference; CSHD paper 4-15), and maps at 1000 year intervals are being finished using the method of modern analogues. The research indicates that the results are quite sensitive to the pollen sum used, to the method of interpolating the date and to the specific method of choosing the analogue (best, 5 best, weighted or not), among others. This was one of the goals we had set in the original proposal. We have made considerable progress in understanding these problems, and one possibility to deal with these is to grid the modern pollen data fields to smooth the fossil data. The best way to do this will be investigated.
(e) Global: For GCM verification, it is desirable to have the largest possible area. For this we are obviously dependent on the availability of data from other sources. We have made progress by developing the first continental-scale reconstruction for North America, and will expand our area in the next grant period as described below.
COLLABORATIONS WITH PARTICIPANTS ||| Top |||
The collaboration between Richard and Gajewski has flourished during the first part of this grant, including two papers (CSHD papers 4-14, 4-15) and the development of the thesis of M. Sawada. A comparison of marine and terrestrial climate reconstructions (CSHD paper 4-14) with deVernal and Richard (Project 2) is the first step toward a larger synthesis of the conditions at 6k, to be done in the coming grant proposal. Collaborations with Project 3, 6, 7 and 10 includes the combining of our climate estimates for a synthesis of the North American conditions at 6ka (CSHD papers 4-15). We have been working with Project 6 in the analysis and synthesis of arctic pollen data (CSHD paper 4-1).
INTERNATIONAL COLLABORATIONS ||| Top |||
Richard and Gajewski have both collaborated with the American PALE project and this has already resulted in a joint publication (Overpeck et al., in press). Gajewski is collaborating with R. Hyde (Norwich) in an investigation of the climate of the past 2000 years. Richard is working with Clark (Duke), among others, in syntheses of fire impacts on vegetation dynamics and G. Miller (Colorado) on Baffin Island vegetation and climate reconstructions.
PROPOSED ACTIVITIES FOR THE NEXT GRANT PERIOD ||| Top |||
The work described above as well as other recent work in terrestrial paleoclimatology had opened a number of questions that will be investigated in the coming grant period. We will continue projects begun during the first two years of the grant, as well as initiating new work suggested by.
(a) The St Lawrence Valley: M. Sawada is currently writing his thesis proposal which will concentrate on the processes of climate-vegetation relationships at several scales. This will permit more accurate paleoclimate estimates, as well as increase our knowledge of how future climate changes may impact vegetation. A first part is the analysis of the existing pollen dataset using GIS and spatial statistics to investigate the mesoscale patterns through time in the vegetation and determine the edaphic influences on dynamics of the major tree species. This may permit the separation of climatic, biological and edaphic factors on vegetation-climate interactions, thereby increasing the reliability of our paleoclimate estimates. In addition, this increases our ability to predict climate impacts on vegetation, a central question in current ecological research (Pitelka 1997 Amer Sci 85:464). He will also use a cellular automata model to generate alternative hypotheses of the influences on plant distribution and change.
(b) Québec: Work will focus on paleohydrological reconstructions for Québec. This is currently a significant gap in our understanding of the climate of eastern North America. This will provide key information to evaluate global climate models as precipitation has proven difficult to estimate. We will continue to reconstruct past lake-level changes in southern Québec (Gaspé and Abitibi) and the Holocene development of an addition peatland will be analysed (Mirabel bog). Both lake-levels and bog development are affected by the interplay of temperature and precipitation and this work will better specify changes in the hydrological component. We will reconstruct Holocene July temperature using chironomids (Walker et al. 1997. J. Paleolimnol) as well as pollen in order to quantify the thermic past of the hydrological budget. Collaborations are in place to pursue this component and a student thesis will be based on it.
We have evidence of relatively abrupt changes in fire frequency around 6ka in some sites and also evidence of water levels up to 3 metres lower than present at other sites. Hydrological modelshelp to explain the conditions necessary to keep a water level at a low stand in the past and relate them to the general circulation. Lake-level reconstructions for the Abitibi region will be related to a hydrological model to reconstruct past hydrological networks (river discharges) at the regional level.
(c) Eastern Canada arctic and Greenland: New data from Somerset Island (CSHD paper 4-8) and a manuscript in prep presenting new data from Banks Island will present the opportunity to try some climate reconstructions for the arctic. A database of pollen diagrams from Greenland was put together several years ago; this will be put into NAPD format and quantitative reconstructions attempted. Our preliminary attempts using the method of modern analogues suggest that there may be insufficient data to apply this method, so we will attempt ordination or response surface methods as well.
We will be applying new methods of core analysis, developed for marine sediments (Rack et al., in press, J. Paleolimnology), to our arctic cores as a way of rapidly obtaining information about changes in sedimentation in these arctic environments. This will be done in collaboration with researchers from Project x.
(d) North America: We will be continuing our work to obtain reliable estimates of the climate during the Holocene. As more data are made available through the NAPD, we will rerun our analyses. We will try to incorporate lake level data (c.f. Guiot) with our pollen-based reconstructions. We will use response surfaces to estimate the Holocene climates in another way. We will analyse the non-analogue surfaces by (a) multivariate analysis of the pollen types to determine which are contributing most significantly to this situation and (b) mapping to attempt to separate transport problems from actual non-analogue situations.
(e) Global: Two possibilities arise for syntheses during the next 5 years. Our reconstructions are now available for North America (above) and published quantitative reconstructions are available for Europe (Guiot). When climates for the North Atlantic will be reconstructed, we can compare our fossil climates with several GCM's across much of the temperate regions of North America. In collaboration with deVernal (Project x), we will attempt to produce maps of the 6ka period for the North America-North Atlantic-European sector. As the PACT project begins to produce data from around Siberia, this synthesis can also be extended to Russia.
(f) PAGES time-stream 1: During the second grant period, we will also work on another aspect of the PAGES science programme: the analysis of the past 2000 years. Data have bee accumulating and it is an appropriate time to attempt larger-scale syntheses of these data. This will continue from Gajewski’s Ph.D. thesis, which summarised climates of the Little Ice Age in eastern North America. Work on reconstructing sea level pressure patterns using proxy climate data (expansion of Gajewski, 1996 Climate changes of the past millenium reconstructed from high-resolution pollen records. (Paper presented at the conference on Climate variations and biodiversity change during the past millennium, Ottawa) will be attempted, using among others, a recently expanded network of sites in northern latitudes (Overpeck et al., in press). New high-resolution (decadal time-scale) charcoal analysis of varved or laminated lake sediments during the last 2000 years (Gaspé, Abitibi) will convey additional proxy climate information to this synthesis
A complementary approach will be the analysis of tree-ring and other data using wavelet analysis, in collaboration with R. Hyde of Norwich University. We have just begun to investigate this, and are in the stage of analysing synthetic series to determine the characteristics of this method.
TRAINING OF HIGHLY QUALIFIED PERSONNEL ||| Top |||
We are training the first Canadian students doing quantitative paleoclimate reconstructions of the terrestrial environment. Our students are leaders in the application of GIS to environmental analysis, (e.g., we have given a GIS workshop at the 27th Annual Arctic Workshop). Jason Soroko (M.A. expected winter 1998) has been working on the reconstruction of the climate of North America using the method of modern analogues. He has gained considerable experience in database programming, and is one of the first people outside of the developers of the NAPD who has used it for mapping and analysis. Mike Sawada (Ph.D. in progress) is investigating scale effects in paleoclimate reconstructions, and has already carried through a joint-authored paper that will become a chapter of his thesis. David Atkinson (Ph.D. expected winter 1998) is developing a GIS model of climate-surface interactions for the arctic and also attempting data analysis using sparse and discontinuous data. Jocelyne Bourgeois (Ph.D. expected winter 1998) is analysing the postglacial climate of the arctic using pollen from ice cores, and will be applying multivariate statistics in her analysis. André Viau has just begun his M.A., and will be similarly trained. Martin Lavoie is finishing his Ph.D. with 4-5 publications in preparation. He made the first North-American whole-system reconstruction of Holocene peatland development for two sites, relating to carbon sequestration and to climatic conditions. With the addition of multi-core lake-level reconstructions, he is one if not the only researcher with this broad approach to paleohydrology in Canada. Manon Savard (Ph.D. in progress, NSERC Fellowship) is beginning her project on paleohydrology of Abitibi based on lake-level changes coupled with a hydrological model. Hans Asnond is beginning his M.Sc. on vegetation history and lake-level changes in the central and eastern Gaspé Peninsula. Christopher Carcaillet (Ph.D., Marseilles) will join Richard’s lab as a post-doctoral fellow working on the reconstruction of Holocene fire frequency and impact on vegetation dynamics.
Publication list from January 1994
CSHD – 4
K. Gajewski & P. Richard
CSHD 4-1 Gajewski, K., M. Garneau and J. Bourgeois. 1995. Paleoenvironments of the Canadian High Arctic derived from pollen and plant macrofossils: problems and potentials. Quaternary Science Reviews 14: 609-629.
CSHD 4-2 Richard, P.J.H. 1994. Postglacial palaeophytogeography of the eastern St. Lawrence River Watershed and the climate signal of the pollen record. Palaeogeography, Palaeoclimatology, Palaeoecology 109: 137-163.
CSHD 4-3 Richard, P.J.H. 1994. Wisconsinan Late-glacial environmental change in Québec: a regional synthesis. Journal of Quaternary Science 9: 165-170.
CSHD 4-4 Richard, P.J.H. and A.C. Larouche. 1994. Histoire postglaciaire de la végétation et du climat dans la région de Rimouski, Québec. pp 49-89 in: C. Chapdelaine, (ed). Il y a 8000 ans à Rimouski. Paléoécologie et archéologie d'un site de la culture plano. Collection Paléo-Québec, no 22, Recherches amérindiennes au Québec et ministère des Transports du Québec, 314 pp.
CSHD 4-5 Marcoux, N. et P.J.H. Richard. 1995. Végétation et fluctuations climatiques postglaciaires sur la côte septentrionale gaspésienne, Québec. Canadian Journal of Earth Sciences 32: 79-96.
CSHD 4-6 Richard, P.J.H. 1995. Le couvert végétal du Québec-Labrador il y a 6000 ans BP: un essai. Géographie physique et Quaternaire 49: 117-140.
CSHD 4-7 Lavoie, M., A.C. Larouche et P.J.H. Richard. 1995. Conditions du développement de la tourbière de Farnham, Québec. Géographie physique et Quaternaire 49: 305-316.
CSHD 4-8 Gajewski, K. 1995. Modern and Holocene pollen assemblages from some small arctic lakes on Somerset Island, N.W.T., Canada. Quaternary Research 44:228-236.
CSHD 4-9 Clark, J.S., B.J. Stocks and P.J.H. Richard. 1996. Climatic implications of biomass burning since the 19th century in eastern North America. Global Change Biology 2:433-442.
CSHD 4-10 Gajewski, K., P.B. Hamilton and R. McNeely. 1997. A high resolution proxy-climate record from an arctic lake with laminated sediments on Devon Island, Nunavut, Canada. Journal of Paleolimnology 17:215-225.
CSHD 4-11 Clark, J.S., and P.J.H. Richard. 1996. The role of paleofire in boreal and other cool-coniferous forests. pp 65-89. in: Fire in ecosystems of boreal Eurasia. J.G. Goldhammer and V.V. Furyaev, eds. Forestry Sciences Vol 48. Kluwer Academic Publishers, 528 pp.
CSHD 4-12 Richard, P.J.H., J. Veillette, A. Larouche, B. Hétu, J. Gray et P. Gangloff. 1997. Chronologie de la déglaciation en Gaspésie: nouvelles données et implications. Géographie physique et Quaternaire 51: 163-184.
CSHD 4-13 Overpeck, J., K. Hughen, D. Hardy, R. Bradley, R. Case, M. Douglas, B. Finney, K. Gajewski, G. Jacoby, A. Jennings, S. Lamoureux, G. MacDonald, J. Moore, M. Retelle, S. Smith, A. Wolfe and G. Zielinski. 1997. Arctic environmental change of the last four centuries. Science.
CSHD 4-14 Sawada, M., K. Gajewski, A. deVernal and P.Richard. 1999. Comparison of marine and terrestrial Holocene climates in eastern North America. The Holocene, 9: 267-277.
CSHD 4-15 Vance, R., K. Gajewski, M. Sawada, J. Soroko, I. Fung, L.D. Gignac, L. Halsey, P. Richard and D.H. Vitt. to be subm. The North American landscape at 6ka.
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