Our Research

The main goal of our global climate research is to determine what controls the climate’s sensitivity to global-scale external forcing. A prime example of external forcing is the observed increase in greenhouse gases due to human activity over the past century and the projected continuation of this trend over the next century. External climate forcings can also be found in the distant past and the climate response to them may guide us in understanding response to future forcings. Present-day climate variations are also relevant to future climate change because information about the feedback mechanisms controlling climate sensitivity may be found in the variability generated by the atmosphere-ocean system as well as the system’s response to the annual cycle of sunshine.

We analyze coupled ocean-atmosphere climate simulations to shed light on climate sensitivity. Having resolved spatial scales of approximately 100 kilometers, these numerical models are relatively coarse compared to regional climate models; however, their global scope allows us to study processes critical to climate variability and climate change that operate on very large scales or involve links among far-flung regions. We also employ earth observations made from space in this work.

The goal of our regional climate research is to understand climate variability and change on spatial scales most relevant to humans and ecosystems. These scales may be quite small in areas of significant surface heterogeneity such as intense topography, where profound climate variations may occur on scales of just few kilometers. These scales are significantly smaller than those that have been the historical focus of climate research. Our main tools for studying this problem are high-resolution (~ 5 kilometer) climate simulations focused on a particular region. A critical component is also comparison of these simulations with available in situ and satellite data.

Our principal laboratory for studying regional climate has been Southern California, whose large mountain complexes generate significant spatial variations in climate. A testament to this climate diversity is the unusually wide variety of ecosystems found in the region. About 20 million people also live in Southern California, making for intricate and powerful interactions between humans and the natural environment as well. Our work in this area is intended to lay the foundation for an understanding of how global climate change might affect the Southern California region.