science activities

focus 2 - regional climate dynamics
rationale

During the past three decades the focus of paleoclimatological research was to diagnose global and Northern Hemisphere climate variability, including teleconnections, rapid transitions, feedbacks, and modes of operation of the climate system. Greenland and Antarctic ice cores and ocean sediments provided excellent data to study millennial scale processes which were found to be controlled by Milankovitch forcing and ocean thermohaline circulation. In addition, dynamical studies on sub-millennial to decadal time scales, including volcanic forcing as well as solar activity changes, revealed clearly that the warm pools of the tropics and the dynamics of the Hadley cell are crucial for the understanding of past climate variability and change. With the increasing spatial-temporal resolution of different types of models came the demand for highly resolved proxy data. New analytical techniques allowed the inclusion of a growing array of paleoclimate proxies and sources for information, such as ice cores, corals, tree rings, laminated sediments, stalagmites, boreholes, documentary data, etc. As a result, an increasing number of high resolution reconstructions, mainly temperature, are now available.

Understanding climate dynamics prior to, and under the increasing influence of humans, forms a much needed basis for improved climate prediction capabilities. Consequently, we place a strong emphasis on studies of regional to continental dynamics of past climate variability on seasonal to centennial timescales. Such studies must include:
- specific runs with models of different complexity and resolution
- multi-proxy reconstructions of the key climate state parameters, such as air pressure, temperature and precipitation
- improved reconstructions of natural climate forcings

This procedure also allows investigation of how the specific patterns, modes and regimes of climate variability changed over time. It also gives us the opportunity to study how strongly regional patterns are dominated by internal variability. In close coordination with Focus 1, Focus 2 addresses these questions by including regions with an as yet sparse data density, such as the tropics and the Southern Hemisphere.


goals

1. To reconstruct important climate state variables for the past, such as air pressure, temperature, precipitation or precipitation minus evaporation (P-E) and wind (circulation) patterns, following the LOTRED concept (see Box; Wanner and Luterbacher 2002). Emphasis lies on periods of rapid climate change, e.g. during the last deglaciation and the Holocene, including the last 1000 to 2000 years.

2. To carry out ensemble simulations of past climate variability with suitable climate models of different complexity. These experiments should be performed in close coordination with the reconstruction activities and, above all, with Focus 1.

3. To understand the interplay between natural and anthropogenic forcing, internal system variability (ENSO, AO/NAO, AMO, QBO, etc.), and feedbacks in the climate system. A special emphasis should be put on teleconnections between the tropics and the higher latitudes as well as on important climate patterns, modes and regimes, as well as testing hypotheses that variability on multidecadal and longer time scales are linked with changes in the ocean meridional overturning circulation (MOC). This will also require coordination with the Foci 1 and 3, as well as with CLIVAR activities.

4. To understand the mechanisms leading to rapid climatic and environmental transitions and the dynamics causing extreme climate events. Activities are coordinated with Focus 3.

5. To understand the response of marine and terrestrial ecosystems to rapid climate change. Activities towards this goal are coordinated with Focus 4 and offer links with the DIVERSITAS program.

6. To identify and quantify the effect of humans on climate and environment, in close collaboration with Focus 4 and in coordination with IHOPE.



PLEASE NOTE: This is draft text pending publication of PAGES Science Plan and Implementation Strategy.