AGU Chapman Conference on Abrupt Climate Change

Byrd Polar Research Center
The Ohio State University
Columbus, Ohio, USA
15–19 June 2009


Program Committee

Conference Objectives and General Description

The main objective of the proposed conference on Abrupt Climate Change is to bring together a diverse group of researchers who deal with paleo-proxy records such as ice cores, corals, marine sediments, terrestrial (lakes and speleothems) archives, and coupled ocean-atmosphere climate models to discuss recent advances in understanding the mechanisms of abrupt climate changes. Since the discovery of the Dansgaard-Oeschger events in Greenland ice cores and their subsequent cousins in the marine sediments of the North Atlantic, search for these abrupt, millennial-scale events across the globe has been intensified. A good compilation of these abrupt climate events are given by Voelker et al. (2002). Since then, the number of paleoclimatic records has increased with most Northern Hemisphere records showing teleconnections with the D/O cycles in Greenland. However, the evidence for the abrupt climate change from the Southern Hemisphere is not clear although there appears to be a one-to-one correlation of the new EDML records of Antarctica with Greenland.

Marine and terrestrial paleoclimate records from the Southern Hemisphere are sparse and do not have enough temporal resolution to characterize the relevant timescales of climate variability. The paleo-records from the northern tropics and subtropics mainly show concordant climate changes with those in the North Atlantic, while asynchronous and even anti-correlated phenomena are exhibited in records from the Southern Hemisphere. For example, the Indian and East Asian monsoon systems seem to correlate with the North Atlantic climate, whereas the South American monsoon seems to operate differently. Furthermore, paleo-proxy records from the equatorial Pacific are characterized by a complex pattern of abrupt climate change that borrows elements from both the Northern and Southern Hemisphere end-members.

Three mechanisms were invoked to explain these abrupt climate changes: (a) freshwater forcing in which meltwater input from the circum-North Atlantic ice-sheets disrupts the meridional overturning circulation (MOC) by preventing the formation of North Atlantic Deep Water (NADW) in the Nordic seas; (b) sea-ice extent in which the albedo effect through altering the local and global energy and thus insulating the ocean from the atmosphere by cutting off the heat and moisture supply; and (c) tropical forcing which calls for a combination of the orbital configuration, El Niño-Southern Oscillation (La Niña) and sea-surface temperature (SST) conditions.

A number of outstanding scientific questions regarding Abrupt Climate Change include:

We invite contributions dealing with any aspect of Abrupt Climate Change, including the numerical models which incorporate proxy records as well as idealized models. Abstracts are solicited for any topic relevant to the above or other questions relating to Abrupt Climate Change.

A Chapman conference is uniquely suited to fruitful discussion of existing records, strategies to acquire new records and research priorities, and of crosscutting science issues: a group of manageable size that includes observational and modeling expertise across sub-disciplines rarely occurs in any other venue.

Format and Schedule

The complete program [PDF] is now available, including the detailed schedule and abstracts.

The meeting spanned five days, with Wednesday afternoon being reserved for the field trip to the margin of the Laurentide Ice Sheet (see below). The schedule was designed to maximize discussion and debate opportunities, and to make the meeting accessible to a broad audience. Each meeting day consisted of a morning and afternoon session, beginning with a keynote lecture, and then continuing with two sessions on each of the main focus areas:

  1. Polar and high altitude ice cores records
  2. High latitude atmosphere-ocean dynamics and the meridional overturning circulation
  3. Low to mid-latitude ocean-atmosphere changes (and coupled systems)
  4. Mechanisms for the onset of past interglacials
  5. Coupled climate models and their performance in simulating abrupt climate change
  6. Abrupt climate change and the collapse of past civilizations

Field Trip — Laurentide Ice Sheet Margin at LGM, Central Ohio

During the LGM Columbus, Ohio was covered by the Scioto Lobe of the Laurentide Ice-Sheet, which reached the Appalachian Plateau to the east. There it disrupted drainage, formed ice-marginal lakes, end moraines, and ice-contact topography (kames) and outwash terraces. The objective of the half-day field trip is to understand the development of these terrestrial features which are dominated by till plain, end moraines and outwash and ice-contact deposits. We plan to make several stops to examine till and outwash deposits. These will enhance our understanding of the Quaternary history of the region and help us visualize changes beneath the ice and at the ice margin.

For more information, please contact Professor Garry Mackenzie of the School of Earth Sciences, The Ohio State University or Lynn Everett.

Fields of Interest

Abrupt climate change, freshwater forcing, meridional overturning circulation, sea-ice and their impact in abrupt climate change, ice cores, paleo-monsoon, paleo-ENSO, ice-sheet dynamics, climate system and theory, general circulation models, and collapse of the past civilization.

General Information

The conference was be held at The Ohio State University's Mendenhall Laboratory. The lab is located on 125 S. Oval Mall in Columbus, Ohio. All oral sessions will be in Room 100.

A detailed map of the university's campus is available.

The welcome reception on Sunday, 14 June was held at Baxter's Restaurant. The restaurant is in the University Plaza Hotel at 3110 Olentangy River Road, Columbus, Ohio.


We wish to gratefully acknowledge the following sponsors for their generous support of this conference.

CWC NSF Ocean Leadership Ohio State U

Further Information

If you would like to receive future updates about this conference, e-mail, or call the AGU Meetings Department at +1-202-777-7332. For information about the scientific program, please contact one of the conveners via e-mail:

Harunur Rashid
Byrd Polar Research Center
The Ohio State University
Columbus, Ohio

Lynn Everett
Byrd Polar Research Center
The Ohio State University
Columbus, Ohio