The group of scientists that make up the Intergovernmental Panel on Climate Change found in 2007 that the warming of Earth’s climate is unequivocal and largely due to human activity. Earth’s climate has changed in the past, though the recent magnitude and pace of changes are unprecedented in human existence....
Understanding how the latitudinal distribution of methane sources changed between stadial and interstadial climate states during the last glacial period can provide important clues about how terrestrial hydroclimate and ecosystems evolved between these different states. The punctuation of the millennial-scale structure by Heinrich events is also of interest in this...
Climate model simulations and paleoclimate proxies are two tools that enable an understanding of the climate history of the Earth. When utilized together, they form a powerful paradigm for understanding past changes. Proxies are the only physical link to the past conditions on Earth, and models “fill in the gaps”...
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Model results for ∆T, ∆δ18Op
Uncertainties in general circulation model (GCM) representations of marine boundary layer (MBL) shallow cloud cover contribute substantially to the spread in model predictions of future climate. Further uncertainties in GCM output arise from an incomplete understanding of cloud-aerosol interactions. For example, the Fifth Assessment Report from the Intergovernmental Panel on...
The South Pole ice core (SPC14), drilled in the field seasons of 2014/2015 and 2015/2016, is an intermediate length, 1,751-m ice core which preserves a 54,000-year record of past climate and atmospheric composition. The SPC14 ice core adds to the spatial grid of ice cores in Antarctica extending into the...
The topics in this dissertation are centered around the way that trees respond to environmental stress in the climates where they occur. Though forests across the planet are expected to experience change in local climate due to historic and ongoing anthropogenic greenhouse gas emissions, the effects of climate change will...
Nitrous oxide is an important greenhouse gas that has both natural and anthropogenic sources in the modern atmosphere (Ciais et al., 2013). This project expanded the knowledge of the history of atmospheric N2O in the geologic past by measuring N2O concentrations in air trapped in very old polar ice. A...
New ice cores retrieved from the Taylor Glacier (Antarctica) blue ice area contain ice and air spanning the Marine Isotope Stage (MIS) 5/4 transition, a period of global cooling and ice sheet expansion. Chronologies were determined for the ice and air bubbles in the new ice cores by visually matching...
Managing wildlands to protect species and ecosystem services in response to climate change is challenging. To develop effective long-term strategies, natural resource managers need to account for the projected effects of climate change as well as the uncertainty inherent in those projections. Vegetation models are one important source of projected...
Reconstructing the sensitivity of past climate to forcings, and of ancient glaciers and ice sheets to this climate, can allow us to better understand the range of climate and cryosphere behavior we may see in the coming centuries. The Arctic is a region of particular importance due to its well-documented...