Pisonia forest where coconuts have already been eradicated on Palmyra Atoll. The forest is lush and green.
David Wahl, PhD
David is a research scientist at the Geology, Minerals, Energy, and Geophysics Science Center. He received a PhD in Geography from UC Berkeley in 2005. Since joining the USGS in 2004, his research has focused on understanding drivers and impacts of Quaternary environmental change, specifically droughts, floods, and wildfire, in North America and the Pacific Islands.
Science and Products
Reconstructing Vegetation and Climate Histories on Palmyra Atoll to Assist with Climate-Smart Adaptation
Project Overview Palmyra Atoll National Wildlife Refuge (NWR) is a critical nesting site for seabirds in the central Pacific Ocean, with ecosystems that are regularly impacted by the El Niño Southern Oscillation (ENSO). Researchers supported by this Pacific Islands CASC project aim to understand how past ENSO-driven climate variability and human activities have affected vegetation and...
Drivers and Impacts of North Pacific Climate Variability
Climate model forecasts indicate an increase in extreme hydrologic events, including floods and droughts, for California and the western U.S. in the future. To better understand what the consequences of this future change in climate may be, USGS scientists are studying the frequency, magnitude, and impacts of past hydroclimate variability and extremes in the region. This project produces well...
Pisonia Forest, Palmyra Atoll
Pisonia forest where coconuts have already been eradicated on Palmyra Atoll. The forest is lush and green.
Kamole (Laysan) Island
USGS and FWS researchers collect sediment cores from Lake Layman (Kamole) to reconstruct vegetation history, nutrient cycling related to bird populations, and climate change over the Holocene.
USGS and FWS researchers collect sediment cores from Lake Layman (Kamole) to reconstruct vegetation history, nutrient cycling related to bird populations, and climate change over the Holocene.
Leonard Lake, California
Early morning fog lifts at Leonard Lake, located in Mendocino, California. (Photo Credit: Dave Wahl)
Early morning fog lifts at Leonard Lake, located in Mendocino, California. (Photo Credit: Dave Wahl)
Extracting a Sediment Core from Leonard Lake, CA
USGS scientists Clarke Knight, Marie Champagne, and Lysanna Anderson (left to right) drive a coring device into the bottom of Leonard Lake to recover a sedimentary core in 2022. (Photo Credit: Dave Wahl)
USGS scientists Clarke Knight, Marie Champagne, and Lysanna Anderson (left to right) drive a coring device into the bottom of Leonard Lake to recover a sedimentary core in 2022. (Photo Credit: Dave Wahl)
Measuring Sediment Core from Leonard Lake, CA
Marie Champagne holds a freshly obtained surface sediment core while Lysanna Anderson takes measurements of the sediment and sediment-water interface length. (Photo Credit: Dave Wahl)
Marie Champagne holds a freshly obtained surface sediment core while Lysanna Anderson takes measurements of the sediment and sediment-water interface length. (Photo Credit: Dave Wahl)
Science and Products
Reconstructing Vegetation and Climate Histories on Palmyra Atoll to Assist with Climate-Smart Adaptation
Project Overview Palmyra Atoll National Wildlife Refuge (NWR) is a critical nesting site for seabirds in the central Pacific Ocean, with ecosystems that are regularly impacted by the El Niño Southern Oscillation (ENSO). Researchers supported by this Pacific Islands CASC project aim to understand how past ENSO-driven climate variability and human activities have affected vegetation and...
Drivers and Impacts of North Pacific Climate Variability
Climate model forecasts indicate an increase in extreme hydrologic events, including floods and droughts, for California and the western U.S. in the future. To better understand what the consequences of this future change in climate may be, USGS scientists are studying the frequency, magnitude, and impacts of past hydroclimate variability and extremes in the region. This project produces well...
Pisonia Forest, Palmyra Atoll
Pisonia forest where coconuts have already been eradicated on Palmyra Atoll. The forest is lush and green.
Pisonia forest where coconuts have already been eradicated on Palmyra Atoll. The forest is lush and green.
Kamole (Laysan) Island
USGS and FWS researchers collect sediment cores from Lake Layman (Kamole) to reconstruct vegetation history, nutrient cycling related to bird populations, and climate change over the Holocene.
USGS and FWS researchers collect sediment cores from Lake Layman (Kamole) to reconstruct vegetation history, nutrient cycling related to bird populations, and climate change over the Holocene.
Leonard Lake, California
Early morning fog lifts at Leonard Lake, located in Mendocino, California. (Photo Credit: Dave Wahl)
Early morning fog lifts at Leonard Lake, located in Mendocino, California. (Photo Credit: Dave Wahl)
Extracting a Sediment Core from Leonard Lake, CA
USGS scientists Clarke Knight, Marie Champagne, and Lysanna Anderson (left to right) drive a coring device into the bottom of Leonard Lake to recover a sedimentary core in 2022. (Photo Credit: Dave Wahl)
USGS scientists Clarke Knight, Marie Champagne, and Lysanna Anderson (left to right) drive a coring device into the bottom of Leonard Lake to recover a sedimentary core in 2022. (Photo Credit: Dave Wahl)
Measuring Sediment Core from Leonard Lake, CA
Marie Champagne holds a freshly obtained surface sediment core while Lysanna Anderson takes measurements of the sediment and sediment-water interface length. (Photo Credit: Dave Wahl)
Marie Champagne holds a freshly obtained surface sediment core while Lysanna Anderson takes measurements of the sediment and sediment-water interface length. (Photo Credit: Dave Wahl)