Global Climate Program
Our Global Climate Program investigates the operation of Earth’s climate system over a range of timescales, encompassing the study of Earth’s climate system past, present, and future. We use diverse techniques, ranging from geochemical measurements that provide indirect ‘proxy’ evidence for past changes in climate to high-resolution, global satellite and in-situ data to constrain changes in the modern climate system. We develop, apply, and interrogate a variety of numerical climate models, from Earth system models of intermediate complexity that represent the key physical and biogeochemical processes operating on the planet, to the state-of-the-art coupled ocean and atmosphere models that inform detailed future climate change projections.
Below, we outline major themes in our current research.
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Climate Dynamics
Our climate dynamics research focuses on how external drivers of climate change impact large-scale atmospheric and oceanic circulation. This includes widening of the tropical belt and expansion of the subtropical dry zones; dynamical and thermodynamical perturbations to mid-latitude storm tracks and the corresponding impacts on hydrology and extreme events; and changes in the ocean conveyor belt, otherwise known as the Atlantic Meridional Overturning Circulation (AMOC). We also seek to understand how climate change impacts prominent modes of naturally occurring climate variability, including the North Atlantic Oscillation and the Pacific Decadal Oscillation. Much of our climate dynamics research focuses on the role of near-term climate forcers (e.g., sulfate and black carbon aerosol).
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Atmospheric Aerosols
Aerosols are micron sized particles suspended in the atmosphere. They alter the radiative balance of the planet and thus contribute to climate change. They also constitute air pollution, and have negative impacts on human health. Our aerosol research addresses both of these issues. We seek to understand how aerosols impact clouds, particularly absorbing aerosols and the so-called “semi-direct” effect. Additional aerosol research seeks to understand their ability to impact the large-scale atmospheric and oceanic circulation, including the tropical rain belt and monsoonal circulations, as well as Arctic climate. Finally, we also address how climate change itself may impact the burden of atmospheric aerosols (the climate change penalty to air quality).
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High-latitude climates
We focus on climate processes and dynamics of ocean, atmosphere and sea ice in high-latitude regions. Our research topics include the interaction between Arctic sea ice and the AMOC, the effects of Arctic sea ice and the AMOC on Northern Hemisphere storm track, climate change and variability of Arctic Ocean circulation and heat and freshwater budgets, North Atlantic and Southern Ocean heat uptake and regional sea level change in high-latitude oceans.
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Climate and Biogeochemistry
We principally use the Earth system model (‘cGENIE’); a model that is unique in its direct applicability to the study of long-term climate in that it represents an unprecedentedly diverse suite of marine nutrient cycles (P, N, Fe, Si), both major and trace elements (Ca, Mg, S, I, Li, Sr, Os), and many of their isotopes, plus the key processes controlling the concentration of O2, CO2, and CH4 in the atmosphere. Many of these capabilities have been developed here at UCR over the past ~6 years.
We apply the model to a wide variety of topical Earth history questions and time-periods. Questions include controls on ocean circulation and oxygenation (and implications for extinctions), constraining the amount and understanding the causes and consequences of massive CO2 release, how CO2 and hence climate is regulated on geological time-scales, and how marine ecosystems differed in the past and the implications for marine carbon cycling and atmospheric CO2. Time-periods of interest span much of Earth history: Precambrian, Ordovician and end Permian extinctions, episodes of intense ocean anoxia during the Mesozoic, ecosystem and carbon cycling disruption and recovery after the end Cretaceous impact, carbon release events in the Paleogene, and the emergence of the modern ice-house climate system from the Miocene to the present-day.
The climate and biogeochemistry group also applies discoveries informed by the geological record to the future. Our knowledge of the past informs future projections regarding the long-term fate of fossil fuel CO2 and duration of elevated global warming, the fate of zooplankton diversity in the ocean, and even the trajectory of future sea-level rise. -
Past Climate Reconstruction
Geochemical analyses of sediments provide indirect, ‘proxy’ estimates of past changes in climate and biogeochemical cycling. We maintain state-of-the-art analytical facilities to evaluate the elemental and isotopic composition of a wide variety of organic and inorganic materials from both marine and terrestrial sedimentary archives across a wide span of Earth history. A particular focus area is using deep-sea sediment cores obtained through ocean drilling to reconstruct climate change across our modern Era.