Abrupt Climate Change in the Northern Mid- Latitudes Circa 5 ka: Pollen-Inferred Evidence for Hemispheric-Scale Climate Change

EPA Grant Number: F13B21520
Title: Abrupt Climate Change in the Northern Mid- Latitudes Circa 5 ka: Pollen-Inferred Evidence for Hemispheric-Scale Climate Change
Investigators: Marsicek, Jeremiah Patrick
Institution: University of Wyoming
EPA Project Officer: Lee, Sonja
Project Period: August 15, 2014 through August 15, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Earth Sciences


This project will not only place the recent global climate change in a long-term context, but will also investigate three primary questions related to possible abrupt changes in the climate system: (1)What relationships exist between rapid climate, hydrologic and ecosystem changes? When evaluated across the Northern Hemisphere, paleoclimatic reconstructions could be used in tandem with hydrologic and ecologic data sets to evaluate whether or not climate-resource relationships were linear, as well as what rates and magnitudes of climate change produced the various local resource changes. Ecosystem changes (e.g., fires, pathogens) may produce important abrupt shifts without direct climate influences, but climate may be vital for sustaining the outcome, or ecosystem responses to climatic changes may be linear (e.g., fast climate changes producing fast ecosystem changes). Either scenario has implications for mitigation and adaptation. (2) At what scale could even modest climatic forcing produce abrupt climate changes?Mapping the extent and rates of temperature changes in the Northern Hemisphere can help evaluate the linkages between climate forcing and extent of abrupt regime shifts. Understanding these scales could provide critical information for planning for potential future changes. (3)What role can intrinsic variability and feedbacks play in amplifying modest external forcing to produce abrupt changes? Changes in the ocean-atmosphere system or in vegetation-atmosphere feedbacks could have been critical in the mid-Holocene, and these should have produced detectable spatial patterns of change. Understanding the roles of such feedbacks in the past could be useful for anticipating changes and effects in the future.


This research will generate temperature data for the Holocene by using fossil pollen from trees and shrubs that have been preserved in lake sediments. Past temperatures will be reconstructed using modern vegetation-temperature relationships, which will be applied to fossil data to achieve temperature estimates from the past. A calibration data set has been compiled for both North America and Europe, and well-dated fossil pollen records exist for both continents, providing an opportunity to generate a temperature record for the last 11,000 years. Using these data sets in tandem with hydrologic and ecologic data sets will allow investigation of Question 1. Once the temperature records for both continents are generated, the spatial patterns of abrupt changes will be evaluated as a means to test Questions 2 and 3. It also will be critical to generate a Northern Hemisphere temperature reconstruction for comparison with climate model output, including a paleoclimate model output.

Expected Results:

Expected outcomes of this work are climate reconstructions, analyses and maps of patterns of abrupt changes, as well as evaluations of the linkages among abrupt ecosystem collapses across the Northern hemisphere during weak Holocene forcing. These results will be useful for anticipating climate change and its effects on ecosystem services.

Potential to Further Environmental/Human Health Protection

Reconstructing temperature changes over geological time allows placing recent and future warming in a long-term context to understand the processes involved and the potential for abrupt changes and other “surprises.” The Holocene provides useful empirical examples of change in ecosystems, species and natural resources like water in a warm world. Global climate change in the near future will result 
in changing distribution, health and functionality of the ecosystems on which humans rely; informed management and conservation strategies are critical in maintaining ecosystem services.

Supplemental Keywords:

climate change, fossil pollen, Holocene;

Progress and Final Reports:

  • 2015
  • Final