Transition to grass-dominated landscapes during the Neogene dramatically changed the recycling of water vapor, ushering in the modern hydrologic regime. We are examining the relationship between changes in vegetation cover and concurrent climate change. See our most recent papers in Earth and Planetary Science Letters (Mix et al., 2013) and Global Biogeochemical Cycles (Chamberlain et al., 2014).
Because of the need to understand the links and feedbacks of the carbon cycle during times of global greenhouse we are examining the Cretaceous climate record preserved in lake sediments in northern China. The Songliao basin offers a unique opportunity to understand Cretaceous climate of terrestrial settings because it contains a nearly complete record of lacustrine sediments deposited throughout the Cretaceous and there is an active drilling project to recover core from this paleolake. Our most recent papers on the Songliao basin were published in Palaeogeography, Palaeoclimatology, Palaeocology (Chamberlain et al., 2013) and Geology (Gao et al., 2015).
We are working to understand the interplay between tectonics and 60 million years of climate change on our planet's largest continent. Our field work is concentrated in Mongolia and in eastern Kazakhstan, where we are collecting paleosol and lake sediments for stable isotopic analysis. Our goal is to understand how uplift of the northern Central Asian mountain ranges--such as the Hangay, Sayan, and Altai Mountains--along with global climate change during the Cenozoic has impacted the climate and ecosystems of Central Asia. Recent work has been published in the American Journal of Science (Caves et al., 2014) and in Earth and Planetary Science Letters (Caves et al., 2015).
Three million years ago, when greenhouse gas concentrations were last as high as they are now and global temperatures were about 3ºC higher than today, the western US was a vastly different landscape with giant lake systems dominating the now-dry desert basins. Using a combination of stable isotope measurements from well-preserved Pliocene soils and modern observations of stable isotopes in precipitation, we are investigating whether or not wet conditions were a product of El Niño-like conditions in the tropical Pacific. See our most recent paper in Climate of the Past (Winnick et al., 2013).
The Early Eocene Climatic Optimum, occurring roughly 52 million years ago, represents a potential Earth System response to projected CO2 emissions over the next couple centuries. While global temperatures were much warmer, most of this temperature increase was concentrated at the high latitudes, reducing the Earth’s latitudinal temperature gradient. This has important implications for the hydrologic cycle, particularly with regards to the transport of latent heat from low to high latitudes. We have collected isotopic records of this time period from a broad latitudinal range and are comparing them with vapor transport models in order to quantify the relationships between latitudinal gradients of temperature, water vapor, and isotopes under a radically different climatic regime.
We are developing long-term climate records from the stable isotopes of paleosols, paleolake sediments, and weathered ashes in an effort to understand how climate and tectonics are linked in the North America Cordillera. Working with collaborators Profs. Stephan Graham (Stanford), Chris Poulsen (Univ. of Michigan), Andreas Mulch (Univ. of Frankfurt), and Todd Ehlers (Univ. of Tuebingen) we are using a wide range of techniques – such as climate models, stable isotope data, sedimentologic and cooling age studies to tease out these interactions. Recent work has been published in Geology (Mix et al., 2011), American Journal of Science (Chamberlain et al., 2012; Feng et al., 2013; Mulch et al., 2015), Geochimica et Cosmochimica Acta (Mix and Chamberlain, 2014), Tectonics (Methner et al., 2015), and Proceedings of the Royal Society of London B: Biological Sciences (Eronen et al., 2015).