Ongoing research projects
Here is an overview of our research program. Details are found elsewhere on this web site, and on member pages. The LPC uses two major approaches to understanding environmental variability. A first is the analysis and mapping of databases of past environments. Emphasis is on quantitative climate reconstruction, mapping and spatial analysis. A second is the gathering and analysis of new paleoenvironmental and environmental data from northern Canada. This includes dendroecological, paleoecological and paleolimnological approaches.
1. Quantitative paleoclimate reconstruction and analysis
There are several aspects to this work, and you can find more information on the member pages, or on the publications and data sections of this web.
1a. Paleoclimate reconstructions
New pollen databases have been developed and are being analyzed to reconstruct past climates. We use the North American Pollen Database to map past climates of North America. A database of Greenland and the Canadian Arctic is being developed to understand the spatial patterns of the climate changes so well recorded in the Greenland Ice cores. The NAPD was used to estimate the spatial patterns of surface climate for the past 18,000 years for North America. In a collaborative project of several groups of the CSHD project we synthesized what is known about the spatial patterns of the climate in North America 6000 years ago. The results can be found here. This work is leading toward a global reconstrcution of Holocene terrestrial climates. If we hope to make global maps of the climate conditions for time periods in the past and to compare these to global climate model simulations, we need to reconcile our estimates from the marine and terrestrial deposits. Our 1999 paper in The Holocene is a step in that direction (see abstract and key figures), as were our papers in 2008 and 2009 in CJES and J Cliamte. The global lake-level database has been used for GCM model verification, but only in a qualitative way. Can these data be used more objectively? Gridded fields of Holocene hydrological status using lake levels can be found here. Several other studies are illustrated on other pages of the website.
But how do you make quantitative estimates of past climates from fossil data? How good are our paleoclimate reconstructions? We are developing new methods to evaluate our quantitative paleoclimate reconstructions.
1b. Climate change and impacts
We are studying the climate of the past century and its impacts on the landscape. Some preliminary maps are shown here.
1c. The carbon cycle
Variations is the distribution of carbon among the various sources and sinks can have profound impacts on the climate. We documented the carbon stored in Sphagnum -dominated peatlands in the northern hemisphere through the postglacial. Data are found here.
1d. The Little Ice Age & Medieval Warm Period
What is the Little Ice Age and the Medieval Warm Period? What caused them? Are these singular events, or is only among many climate changes on the century scale? And what happens to the climate system on decadal scales during these century-scale event? The Little Ice Age had a significant impact on the vegetation of eastern North America. So did previous century-scale climate changes, such as the Medieval Warm Period. What are these impacts. How did we determine this? These are the questions we are investigating. Some leads to more information are found here.
2. Impact of human activities on the North American Ecosystems - 18ka to present
A new research program involves the we are using a large database of archaeological radiocarbon dates to study (a) the impact of past climate changes on the population numbers and cultures of prehistoric North Americans and (b) attempting to understand the imapcts of human activities on the vegetation and climate of North America - from the initial colonization of North America 15,000 years ago, through to the the arrival of Europeans, to the present. Our first studies on this subject appeared in 2009-2010, and we are continuing this program in the future.
3. Large-scale paleoecological studies
One important biogeographical question involves understanding how trees migrated over large distances during the Holocene. It is well established that taxa migrated at rates exceeding 500 m/yr during deglaciation in eastern North America. Did certain taxa migrate as a front or did migration take place via rare establishments of outlying populations in advance of the main population center. Were edaphic conditions more important than climate in constraining the presence or absence of certain taxa during migration? If so, at what spatial scales and for which taxa were such constraints important? For example, we used the FORSKA model to investigate how climate variability affects patch model behaviour in the boreal forest.
The paleo-approach can halp us to interpret changes in the landscape being observed today. For example, by analysing pollen at higher taxonomic or temporal resolution than previous studies, we showed how some observed recent changes in the forests actually began centuries ago. Further work has documented the migration of the major taxa of aquatic macrophytes and the history of the development of Sphagnum dominated peatlands. A key study was analysis of the role of Populus (aspen, poplar) in the postglacial vegetation succession.
3b. Treeline studies
Although the late Holocene vegetation and climate history at treeline in northwestern Québec has been studied, no pollen diagrams were available from this region. Fourteen new pollen diagrams are providing data about treeline variations in this region. Current work is investigating the spatial and temporal resolution of pollen diagrams. Click here for more information. The spatial pattern of treeline in northern Quebec, and other ecotones is characterized by a patchy transition from forest to tundra. What causes this pattern. A CA model can help us to understand the transition between different vegetation types in the presence of environmental gradients and disturbances; details here. Modifying the FORSKA model to include interannual climate variability enabled treeline to be more accurately modelled.
3c. Paleoenvironmental studies in the southwest Yukon
Current work is documenting treeline variations in the Kluane Lake region of the southwest Yukon, using a combination of pollen, paleolimnological and dendroecological techniques. Palaeoecological studies based on the analysis of pollen in lake sediments offer the potential for high resolution and well-dated independent records of past vegetation and climate. Results from Sulphur Lake, located in the southwest Yukon (60.95N, 137.95W), can be found here.
A combination of paleoecological and paleolimnological methods is being used to understand ecosystem evolution in the southwest Yukon. This includes analysis of the diatoms, chironomids and ostracods from the modern sediments of the region. Variations in climate in the have been studied for years by the analysis of glacier variations. How did these climate changes impact the ecosystems of the region? How fast does vegetation respond to climate changes of different duration and frequency? Dendroecological studies of treeline and post-fire succession provide information about the response of the forests of the region to climate changes of the past century.
3d. High resolution paleoenvironmental studies in the Gatineau Hills
We also are working locally, in the Ottawa region. There are numerous lakes in the Gatineau Hills, includingh some with varved sediments. High resolution records from a series of sites in the region will enable us to attempt detailed time-space reconstructions of the vegetation and cliamte history of the Ottawa-Gatineau region. We are also attempting detailed paleoclimate reconstructions from the mer Bleue peatland, just outside Ottawa.
4. Environmental change in the Canadian Arctic
One area of special interest is the Canadian Arctic. We are studying environmental changes in the Arctic at several time and space scales. Climate maps of the Canadian arctic are derived from only 4-5 climate stations, with finer-scale interpolations estimated by the author's experience. However, a unique dataset - the PCSP weather data are being used to better understand the mesoscale summer temperature of this region. Since the 1950s numerous expeditions and research groups have conducted work in the High Arctic. Most if not all groups gathered data of one form or another. Often, information that was incidental to the main goals of the research were collected and not used. Much of this information has never found its way into organized, available data sets and are now in danger of being lost. These data are available here.
Another project we have been involved with is to attempt to prepare an inventory of data sets for this region, identifying those at risk, to pave the way for their retrieval, clean up, and eventual integration. This work is being conducted with external collaboration. More information about the Inventory and Rescue of High Arctic Climate and Climate-related Data Sets Project may be found here. These data are all discontinuous, with an irregular spatial distribution. A empirical mesoscale model of July temperatures was developed to obtain finer-scale data for research purposes. More information is found here (coming soon). The Franklin expedition was lost during a period of severe weather in the mid 19th century. This century has seen a significant warming. What do we know about the recent climate history of the Arctic? Here is more information.
As opposed to Greenland, the Holocene climate history of the Canadian Arctic is practically unknown. There has been considerable activity in reconstructing postglacial climates of North America from fossil pollen. Methods used and some results are presented elsewhere on this web site. But few efforts have been made in the Arctic. The first reason is simple - there are few data available. Elsewhere on this site, we explain some of the efforts we are doing to collect new data from the arctic. A second reason for the lack of progress is that analysing climate from arctic pollen assemblages will require different approaches from those used on forested regions. Work is also ongoing to develop these methods. New pollen diagrams from this regions are telling us about vegetation stability and change in the central and western Arctic. See more information here.
It is expensive to obtain these data. To better exploit our lake sediment data, we are also performing paleolimnological analyses in the arctic. This includes the analysis of diatoms, chironomids, ostrcods and cladocera from our network of sites from across the arctic. As a first step, we analysed the physical and chemical limnology of numerous arctic lakes. Information can be found here. More information can be found on member pages.
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