Wk 7: Hungate

Climate Change and Terrestrial Ecosystems: from the globe to the cell and back
Bruce A. Hungate

Associate Professor, Ecosystem Ecology

Dept. of Biological Sciences, Northern Arizona State Univ.

4-5:30, Tuesday, November 10, 2009, LH 1
PLATO Royalty Lecture Series[1]


Bruce Hungate (10 November 2009) presented a focus on plants and microorganisms in ecosystem processes, (specially carbon, water, and nutrient cycling as biogeochemical responses to rising atmospheric CO2 in scrub woodor grasslands with species infestation such as piñon-needle scale in juniper decomposition.)

Abstract: Responses of humans to the challenge of global warming are unclear – whether to tax carbon emissions, implement cap and trade systems, continue funding the science, or try engineering carbon sequestration, aerosols in the atmosphere, mirrors in space, or even something creative with ice cubes.

Global warming challenges natural ecosystems, too, and many of those responses are also unclear, not just in the magnitude but also in the sign of their impacts. These feedbacks are important. As the concentration of carbon dioxide and other greenhouse gases increase in the atmosphere, the climate warms and precipitation patterns change. Plants and soil microorganisms in ecosystems respond to these changes. Their responses produce and consume greenhouse gases, and they produce and consume enough of them that any changes are likely to affect the pace of climate change.

These feedbacks are interesting because they scale between organisms and the Earth’s climate system, literally from the globe to the cell and back. And these feedbacks are interesting because they contribute to the policy debate about global climate change: how much can we expect natural ecosystems to continue to buffer atmospheric CO2 rise? Can we manage natural ecosystems to ameliorate climate change?

In this presentation, Dr. Hungate discussed some of the expected responses of terrestrial ecosystems to climate and atmospheric change, focusing on responses that influence the climate system, for example changes in carbon sequestration caused by elevated CO2, nitrogen fixation, and fluxes of trace gases from soils. He then discuss climate mitigation, including an overview of global emissions today with respect to emissions targets, mitigation, and geoengineering.


The Speaker: Dr. Bruce A Hungate is a Professor of Ecosystem Ecology at Northern Arizona University, and the Director of the US Department of Energy’s Western Regional Center of the National Institute for Climatic Change Research. He has bachelor’s degrees in Music, English, and Biology from Stanford University and a PhD in Integrative Biology from the University of California at Berkeley. He has published over 80 scientific articles on environmental issues. Dr. Hungate’s research focuses on the ecology of global warming, including human contributions to greenhouse gas emissions and how these emissions might be offset or mitigated. He also studies responses of natural ecosystems to environmental change, and how ecosystems affect the climate system. His research spans grasslands, woodlands, forests, and rivers in the temperate zone, boreal forests in Siberia, and tropical forests of the Amazon basin. Through teaching, research and outreach, Dr. Hungate hopes to raise awareness of the role of earth system science for managing global environmental change.

Companion Reading

( Note to Students:  Please be aware that your program might have additional or different reading! Check your respective program web site. )

  1. Hungate BA, van Groenigen KJ, Six J, Jastrow JD, Luo Y, de Graaff MA, van Kessel C, Osenberg CW, 2009. Assessing the effect of elevated CO2 on soil C: a comparison of four meta-analyses. Global Change Biology. 15: 2020-2034
  2. Hungate BA, Dukes JS, Shaw MR, Luo Y, Field CB, 2003. Nitrogen and Climate ChangeScience 302:1512-1513

[1] This Lecture is sponsored by Evergreen’s PLATO Royalty Fund, established with royalties from computer assisted instruction (CAI) software, written by Evergreen faculty John Aikin Cushing and students in the early 1980’s, for the Control Data PLATO system.