The Keenan Group, Berkeley

Department of Environmental Science, Policy and Management, UC Berkeley

Climate and Ecosystem Sciences Division, Lawrence Berkeley National Lab.

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The overarching objective of this interdisciplinary project is to improve understanding of the global exchange of carbon between terrestrial ecosystems and the atmosphere, by leverage new theory and observations in land, atmospheric and space-based research at high spatial and temporal resolutions.

We use eddy-covariance observations together with a suite of NASA, DOE and other partner agency data, to improve estimates of the partitioning of carbon between the biosphere and the atmosphere, advance theory on ecosystem scale photosynthetic light- and water-use efficiency, and develop a high-resolution framework that uses machine learning to combine these advances. By bringing together the "bottom up" and the "top down," we aim to elucidate the controls of inter-annual variability and transform our ability to characterize carbon-climate feedbacks. This will improve insight into the processes that govern global carbon uptake and functional responses that control the magnitude of carbon cycle feedbacks, a key goal in order to improve our ability to predict the future evolution of the Earth System.

See resulting publications here.

PI: Keenan
Co-Is: Fisher (JPL), Michalak (Stanford)
Funding: NASA Interdisciplinary Science
proxima


Extreme events such as drought, heatwaves and wildfire are becoming increasingly prevalent in the eastern US and will likely continue to be over the rest of this century. The HELIOS project focuses on understanding the impact of such extremes on both coastal ecosystems and water resources.

Ecosystem water use plays a large role in determining surface water availability, and thus streamflow, and societies water resources. Water use and streamflow are highly sensitive to multiple climate extremes, which frequently lead to devastating impacts on natural ecosystems and human society. For instance, co-occurrence of extreme precipitation and wind can result in massive infrastructural damage. Combined drought and heat can lead to widespread forest mortality, and extreme wildfire, as recently experienced along the US west coast. In this project we examine ecological responses to compound and sequential extreme events, and the resulting impact on coastal water resources, both in recent decades and over the coming century.

Publications: We're just getting started. Watch this space!

PI: Keenan
Funding: DOE Early Career Award
proxima


Water availability plays a large role in the global carbon, water and energy cycles, and limits ecosystem productivity in almost all biomes. The SMAP project leverages information from NASAs soil moisture active-passive sensor within a model benchmarking framework, combining both the carbon and water cycles to quantify the role of water in regulating global ecosystem state and function.

Limits on ecosystem productivity due to water availability manifest through constraints on the amount of biomass that can be sustained, and on the amount of photosynthesis that can be maintained. These constraints are most evident in the world’s warm and arid environments, where water plays the dominant role in primary production and where foliage cover, plant water use, and photosynthesis are all tightly coupled. They are also evident in the world’s cold regions, however, where freeze-thaw states dictate landscape hydrology and water availability. The consequences of changes in water availability on global ecosystems are thus potentially dramatic. Understanding both the current constraint of water availability on ecosystem function, and the consequences of likely future changes, is therefore an urgent need - one that we aim to address.

Publications: We're just getting started. Watch this space!

PI: Keenan
Co-I: Girotto (UC Berkeley)
Funding: NASA SMAP Science Team
proxima


LEMONTREE will develop a next-generation model of the terrestrial biosphere and its interactions with the carbon cycle, water cycle and climate.

The LEMONTREE approach draws on eco-evolutionary optimality theory as a basis for building ecosystem models that rest on firm theoretical and empirical foundations, and that can be incorporated into the land-surface component of climate models. These models should eventually yield more reliable projections of future climates. This could give a newfound ability to address issues in sustainability, including the potential to maintain the biosphere’s capacity to regulate the carbon cycle while benefiting human well-being and development. LEMONTREE is an international consortium with participants from UC Berkeley, The University of Reading, Imperial College London, Columbia University, the University of Pittsburgh, Utrecht University, Seoul National University, Texas Tech University, Tsinghua University and the Swiss Federal Institute of Technology in Zurich.

Publications: We're just getting started. Watch this space!

PI: Harrison, U. Reading UK
Co-Is: Keenan, Prentice, N. Smith, Ryu, W. Han, Gentine, Stocker, Liang, Vidale, Graven, Rebel, De Boer
Funding: Schmidt Foundation VESRI
proxima


Flash droughts are typically distinguished from conventional droughts on the basis of their rapid onset and/or duration. This project aims to examine the role of vegetation in flash drought events.

Flash droughts come on seemingly without warning, and sometimes with devastating effects. Another distinguishing feature of flash droughts is that they are largely driven by evaporative demand. This has implications for the dynamics and predictability of flash droughts in a changing climate. It also suggests that understanding and prediction of flash droughts is inherently linked to understanding and prediction of high evaporative demand periods, including heat extremes that persist for several days to weeks. In this NSF PREEVENTS project, we are working to advance the understanding and subseasonal-to-seasonal prediction of flash droughts and their associated heat extremes. At Berkeley, we are developing machine-learning based estimates of photosynthesis, evapotranspiration and respiration at high resolution, in combination with remotely sensed estimates of evaporative stress, to define and characterize flash drought events.

Publications: We're just getting started. Watch this space!

PI: Zaitchik (Johns Hopkins)
Co-Is: Keenan, Badr (Johns Hopkins), Otkin (U. Wisconsin-Madison), Anderson (USDA)
Funding: NSF PREEVENTS
proxima



Photosynthesis FP


2016-2019



Plants adapt and have the potential to acclimate, through changes in resource allocation, to the environment. This project aims to develop a theory of photosynthetic acclimation from first principles.

Under this project we are developing photosynthetic theory and using it to generate and test hypotheses regarding the mechanisms governing the biotic control of photosynthesis in response to climate. We combine recent understanding of optimal resource allocation with a large global databases of physiological measurements. Our results suggest that plants acclimate to growth conditions in a manner that fulfills co-optimality criteria. The resulting hypotheses regarding acclimation responses have large implications for the response of vegetation, and thus the global carbon cycle, to ongoing climate change.

See resulting publications here.

PI: Keenan
Funding: DOE LDRD
proxima



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