Past and Future Climate
The Climate Modeling Alliance (CliMA) is a coalition of scientists, engineers, and applied mathematicians from Caltech, MIT, the Naval Postgraduate School, and NASA's Jet Propulsion Laboratory. CliMA is building a new Earth system model that leverages recent advances in the computational and data sciences to learn directly from a wealth of Earth observations from space and the ground. The model will harness more data than ever before, providing a new level of accuracy to predictions of droughts, heat waves, and rainfall extremes.
How has the earth's climate varied in the past? We know from ice core records that the CO2 content of the atmosphere is correlated with climate variations. These records also tell us that global climate has many timescales of variability, from one hundred thousand to tens of years. We use records from deep-sea corals and ocean sediments to understand the ocean's role in these processes. We mine the information in tropical cave deposits to constrain the relative roles of low-latitude processes like El Niño, and high-latitude processes like deep ocean circulation, in setting past climate change. Models ranging from simple reservoir exchanges in the carbon system to fully dynamic ocean circulation examples help us interpret the data from these climate archives. Our goal is to understand why there are glacial cycles in the past, and the rapid changes associated with them, with the hope of better understanding our climate future.
Tools and Facilities
Coral Culturing and Analysis
We have coupled two disparate techniques, growing corals in controlled cultures and nanoscale analysis of metals and isotopes via Secondary Ion Mass Spectrometry (nanoSIMS), to probe the way corals make their skeletons. Our goal is to understand how chemical tracers are incorporated into living coral hard parts to better understand how to read them for the record of past climate change in the oceans. In addition, as ocean acidification is a certain outcome of burning fossil fuels, we hope to understand how corals will react to their future environment, perhaps even finding the telltale signals of stress in the trace metal chemistry of their skeletons.stratigraphy.
Measurements of trace metals in the environment and precise dating of corals and cave deposits all require extremely clean conditions for processing samples. The clean room, custom designed for this purpose, is unlike any built earlier. It has air cleansed of almost all particles and has been constructed entirely from non-metallic materials. Measurements of corals and stalagmites in it reveal how climate has varied in Earth's past and how carbon cycles between the biosphere, the atmosphere, and the oceans.
Geochemistry Instrument Lab
The instrument lab houses three inductively coupled plasma mass spectrometers (ICP-MS). They are used to measure metal isotope ratios and Uranium-Thorium (U-Th) dates of samples that have been chemically processed in the clean room. They are also used to measure sulfur isotopes in the modern ocean and in ancient rocks to develop a quantitative understanding of how oxygen levels in the atmosphere have evolved over Earth's history.