Climate change in one part of the globe can have a significant impact on climate elsewhere. Such climate relationships over long distances are called teleconnections. Teleconnection patterns also exist in the weather, where they can persist for periods of weeks to years and influence for example storm track positions, temperature, and precipitation. The most well-known example of such a weather teleconnection is the El Nino effect in the central Equatorial Pacific, that is known to influence precipitation patterns in areas as remote as the continental US and the horn of Africa. The observational climate record is too short to identify all teleconnection patterns that exist in Earth's climate system. Natural climate change events that happened in the past provide a unique opportunity to study the working of such teleconnections on long timescales, allowing a better understanding of the dynamics of Earth's climate.

Heinrich Events are a type of abrupt climate change that happened repeatedly during the last ice age. During these Heinrich Events a large fleet of icebergs out of the Hudson Strait created a period of extreme cooling in the North Atlantic. We know that these events strongly disturbed rainfall patterns in the tropical monsoon regions, creating changes in the atmospheric concentration of methane. However, their climatic teleconnection to the southern hemisphere high latitudes remains unclear. The goal of the project was to use ice cores from both Greenland and Antarctica to identify the impact of Heinrich events both close to, and far away from, the North Atlantic. Any consistent relationship between climate changes seen in Greenland and Antarctica would reflect a bipolar climatic teleconnection.

The project performed high-resolution and high-precision measurements of the isotopic composition of atmospheric nitrogen in the Greenland GISP2 (Greenland Ice Sheet Project 2) ice core, which is a sensitive recorder of Greenland climate change. Measurements were made on 643 unique sampling depths, with 312 measurements completed in replicate. Contrary to expectations, the data show that Heinrich events do not impact Greenland climate, despite the proximity to the North Atlantic.

The project further created a new high-resolution and high-precision record of atmospheric methane from the same GISP2 ice core. Measurements were made on 995 unique sampling depths, all of which completed in replicate. The project identified the timing of five Heinrich events in the Greenland ice core via the aforementioned signal in atmospheric methane. They further synchronized the timescale of the Greenland ice core to that of Antarctic ice cores, using the fact that variations in atmospheric methane are synchronous at both poles. Using this bipolar timescale synchronization, the project found that Antarctic climate showed abrupt warming events coincident with the Heinrich events in the North Atlantic.

The project identified a new kind of teleconnection pattern that had not previously been recognized. The synchroneity of changes seen in Antarctic climate and atmospheric methane suggests that the teleconnection pattern likely has an atmospheric origin. The global impact of Heinrich events has a counterintuitive spatial pattern, in which proximal sites (Greenland) are less impacted than remote ones (Antarctica). The project will lead to future research to better understand these puzzling observations.

The award provided support for a graduate student at Oregon State University, contributing to an educated workforce in STEM (science, technology, engineering, and mathematics) fields. The award further provided opportunities for professional development for the principle investigator, who is an untenured faculty member at Oregon State University

For the duration of the project researchers visited local middle schools to provide polar science education reaching around 300 students annually, and on a regular basis provided laboratory tours and lectures to members of the public.

Last Modified: 09/22/2022
Modified by: Christo Buizert