The Lammi Meeting: 4-7 April, 1997

The first meeting of the CAPE Holocene Project was held in Lammi, Finland on 4-7 April 1997. Regional working groups began their compilations in the fall of 1996, following protocols established at the London organizational meeting. The Lammi meeting was attended by nearly 40 scientists from Canada, Denmark, Finland, Germany, Iceland, Norway, Russia, Sweden, United Kingdom, and the United States, who are currently active in Arctic research (see List of Participants, Regional Co-ordinators). The first day was devoted to presentations of regional terrestrial and shallow shelf syntheses, and a discussion of the BIOME and EVE models that convert climate model output into vegetation.

On the second day, the group revisited the biome definitions used in the regional compilations and revised the vegetation classification system, reducing the number of biomes, while providing subdivisions that allowed all major vegetation assemblage types to be identified. The final classification system (Fig. 2) and the pollen assemblages on which they are based will be posted on the CAPE Homepage. The group then developed a scheme to provide semi-quantitative climate interpretations from the vegetation assemblages, mostly in terms of relative change in growing-season temperature and effective moisture, both defined in comparison to modern conditions. Each working group re-evaluated their individual sites in terms of the revised criteria, and the final vegetation and climate interpretations were entered into computer spreadsheets.

The marine group spent the second day developing a protocol to derive surface water-mass characteristics from a more diverse range of proxy evidence. The most important elements for the CAPE reconstructions were the extent of seasonal and permanent sea ice, and summer sea surface temperatures, the later as a proxy for the incursion of relatively warm Atlantic water into the Arctic Ocean and its marginal seas. Marine reconstructions are hampered by the limited number of sites available and the extreme difficulty precisely dating the available cores in the Canadian Arctic Islands, and the Beaufort, East Siberian and Laptev Seas. Important regional datasets that characterize surface water conditions are available for the Canadian Arctic and to a lesser extent the Svalbard Archipelago from the distribution of Bowhead whales. Marine bivalves with diagnostic water mass affinity also provide important information for coastal sites in the Canadian Arctic, Greenland, and Svalbard.

On the final day, the group evaluated the spatial pattern of vegetation zones in 1ka time slices, and summer temperature reconstructions, concentrating on the 10ka and 6 ka time slices, for which we were able to compare GCM summer temperature anomalies and reconstructed vegetation from the NCAR-GENESIS-EVE model and the BIOME 6000 vegetation reconstruction. It was possible to generate color transparencies of the 6ka and 10 ka GCM temperature anomalies on which the semi-quantitative estimates of temperature from nearly 400 individual sites were superimposed in a color- and size coded scheme corresponding to the sign and magnitude of change reconstructed from the proxy data. Strong spatial patterns emerged that were by in large concordant with the GCM simulation.

Products

The primary product to emerge from the Lammi Workshop, for which the participants felt most confident that the uncertainties were minimal, is a series of vegetation assemblage (or biome) maps for the terrestrial regions of the Arctic. These reconstructions were based strictly on the actual pollen data, converted to vegetation assemblages based on objective criteria defined for each of the 12 regions. The data can be portrayed in one-thousand-year time slices for the past 10,000 years.

A second order interpretation is the semi-quantitative interpretation of temperature anomalies from the changes in vegetation assemblages. Maps showing the temperature anomalies plotted at the location of each data site are also available in 1 ka time slices for the past 10ka. For 6ka and 10ka, the anomalies observed from the vegetation changes are compared to summer temperature anomalies predicted from the GENESIS GCM simulations.

It is essential for CAPE to make the results of these efforts as widely available as possible. To accomplish this goal, we intend to publish the individual regional syntheses, the circum Arctic syntheses, and the comparisons with the GCM results in a special volume of an international journal, most likely The Holocene or Arctic.. Additionally, the results of the syntheses and comparisons are available electronically here at the CAPE website (Go to Maps). Until the compilations are published they will be protected by a password known by the contributors to the Lammi meeting.

Accomplishments and Future Directions

The consensus of the participants at the Lammi meeting was that major strides were achieved in the synthesis of the terrestrial data. Particularly encouraging was the development of a consensus scheme to characterize Arctic vegetation by a limited number of biomes, and the real-time visualization of these reconstructions for the entire Arctic. The marine synthesis was less complete. It was hampered by more complex, multi-proxy datasets, and less comprehensive spatial coverage. The history of sea ice variations, the single most important marine surface parameter remains elusive, although promising data are emerging using marine dinoflagelates as sea-ice proxies. However, few high-resolution Holocene dinoflagelates records for the Arctic have been developed yet.

Short-term goals: The Lammi participants will reconsider all of their sites and review all of the regional compilations based on the discussions at the meeting. Revised datasheets will be resubmitted within two months for a second generation of the synthesis maps.

Longer-term goals:

Marine Working Group:

1.) Determine the terms for data compilation.

2.) What are the most reliable proxies and how can they be interpreted in terms of specific environmental parameters?

3.) What can be deduced about climate variability?

Terrestrial Working Group

1.) Better calibration of the pollen to biome to climate transformation

2.) Are there additional sites to provide better geographic coverage

3.) What proxies other than pollen should be included?

4.) Ensure that all primary data are archived appropriately

5.) What can be deduced about climate variability?

6.) Biomization of Arctic vegetation

Follow-on meeting

Depending on the results of the re-mapping aspect following each working group's revised compilations, a second meeting may be appropriate. This may be associated with a major meeting or a stand-alone meeting, depending on the anticipated duration. A meeting of more than two days should be independent of any other meeting.

The regional compilations should be presented in a special session of a major international meeting. The December, 1998 American Geophysical Union Meeting was suggested as one possibility.

Future CAPE Plans

Proposals were presented for two new pan-Arctic syntheses.

1.) A high resolution synthesis of the last 1ka to 2 ka, addressing seasonal to decadal climate change.

2.) Synthesis of the Last Glacial Maximum (LGM), ca. 25ka to 10ka.

Proposals for both projects will be submitted to the CAPE Steering Committee for consideration in the near future. The High Resolution Project could be underway by mid 1998 whereas the LGM Project would by unlikely to begin until the Holocene Project was completed.

Summarized for the CAPE Project By:

Gifford H. Miller, Anders Elverhoi, Sheila Hicks


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