Dr Chris Brierley
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Department of Geography
University College London
Tel.: +44 (0)20 7679 0571
I am interested in the role of the ocean under climate change. I use climate models to uncover this role both in the geologic past and the future. I joined UCL from Yale, where I worked closelyon the Pliocene climate. Prior to that I researched ocean model uncertainty and its impact on climate projections at Reading University.
I discovered that the meridional (North-South) extent of warm tropical waters was much larger in warm past climates, and have looked at the consequences of this for the climate of past 5 million years (more). It has been suggested that tropical cyclones (e.g. hurricanes) play an important role in the climate system and we have discovered a climate feedback involving them, which may explain permanent El Niño (more). I have published several articles looking at the contribution of uncertainties in ocean model parameter values to the total uncertainty of climate projections (more). You can find out much more about these topics and more on my research page.
I have been involved in publishing a quick guide to climate change with. If you have specific questions about climate change, I recommend that you look at the results of the NERC climate change challenge and the that I compiled about it.
As new data emerges, our interpretation of the early Pliocene climate continually evolves. More and more data from the last few years indicate a persistence of a significantly reduced zonal temperature gradient in the equatorial Pacific, which is associated with climate conditions usually referred to as a "permanent El Niño". We have collected together data from a variety of regions in both Pacific and Atlantic oceans to reconstruct the meridional temperature gradient in the ocean during the early Pliocene. Our
I have used an atmospheric general circulation model to look at the implications of a reduced meridional temperature gradient (by forcing it with hypothetical surface temperature boundary conditions, representative of our new understanding of the early Pliocene). I've explored the changes in the global circulation and precipitation patterns, along with inferences about the ocean heat transports. The Walker circulation is virtually removed by the imposed SST boundary conditions. The latitudinal extent of the Hadley cell increases only slightly, but the strength of the Hadley circulation is substantially reduced, which results in a weakening of the poleward heat transport by the atmosphere in the low- to mid- latitudes.
Previous research shows that oceans models predict a reduction in the ocean heat transport in the early Pliocene, rather than the warming my results would indicate. The issue of poleward heat transport in the early Pliocene has been called the
The temporal evolution of the meridional and zonal SST gradients in the tropical Pacific differ over the past 4 million years. We have used atmosphere modelling to determine the relative effects of the zonal and meridional gradients on glacial inception. Tropical merdional SST gradients, thought to be relatively constant until our
Tropical cyclones (such as hurricanes and typhoons) can have disastrous human impacts. There is substantial interest in the response of tropical cyclones to climate change, and recent evidence suggests they may also affect the dynamics of the climate system. Yet some fundamental issues remain unclear. An area of substantial research is the response of tropical cyclone activity in changed climates. There has been little work performed however on the question of whether tropical cyclones influence various components of the climate system. We have used our knowledge of the early Pliocene is to investigate this issue.
It is logical that the altered SST pattern of the early Pliocene has a different spatial distribution of tropical cyclones. Our atmosphere simulations show a surface warming and a reduction of windshear (with the reduction of the Hadley Cell), both of which would act in concert to form tropical cylceones more easily. Tropical cyclones are a substantial source of upper ocean mixing and altering the spatail location of that mixing could have interesting consequences. Were the mixing to impact the ocean pathways that cold water takes before upwelling in the east equatorial Pacific, then sea surface temperatures would be expected in a region already known to have global impacts - potentially feeding back onto the tropical cyclone distribution. This work was published in Nature (
I have also looked at how hurricane mixing is parameterized in climate models. We have performed a series of simulations using various temporally different representations of intermittent mixing. We find the spatial pattern is the response is robust, although the magnitude varies somewhat. This work (
Atmosphere-ocean general circulation models are the best tools available to provide policy-relevant predictions of the climate's response to a change in the amount of atmospheric CO2. They include parameterisations of physical processes that cannot be resolved explicitly. There is uncertainty in the numerical values (parameters) involved in the parameterisation of ocean physics. This is called ocean parameter uncertainty. My work was the first investigation of the effects of this uncertainty in a complex climate model.
I created a database of ocean parameters and their uncertainty ranges for a complex model (HadCM3) through expert consultation. A perturbed physics ensemble was then created from the highest priority parameters. The ensemble represents an upper bound of ocean parameter uncertainty. Each ensemble member has been run to a preindustrial quasi-steady state. I looked at the effects of ocean parameter uncertainty on the long-term climate state: there is surface temperature uncertainty of greater than 2.5°C at high latitudes.
I then performed a climate change experiment with CO2 increasing by 1% per year with the ensemble. The effects of ocean parameter uncertainty on the climate change signal can be detected above natural variability.
GEOG1002 Environmental Systems and Processes – An introductory course providing a comprehensive understanding of the fundamentals of the Earth's atmosphere, hydrosphere, lithosphere, and biosphere. I contribute lectures on weather, climate and climate change.
GEOG2020 Hydroclimatology – A course introducing the water cycle including components on meteoric water, surface water and ground water. I contribute lectures on the atmospheric water budget and climate variability.
GEOG3037 Climatology – This course describes the workings of the climate system and provides an introduction to climate modelling. I convene the course and deliver all the content.
GEOGG120 Models in Environmental Science – A course aimed at introducing students to a broad range of environmental models, interspersed with hands-on practice and theory. I contribute a class on climate models.
GEOGG130 Climate Dynamics – A course focused on the climate system: how we observe it, how we explain and what we project for its future. I convene the course and deliver all the content.
GEOGG133 Past Climates – A course describes the previous history of the climate system along with techniques of palaeoclimate reconstruction. I contribute a lecture on role of climate models in palaeoclimate.
GEOGG134 Climate Modelling – Explains how the equations that describe the atmosphere and ocean are solved numerically to create meaningful predictions. Involves running HadAM3, so is heavy on the practical side. I convene the course and deliver all the content.
Previous Courses (taught at Yale) See here for further details.
Introduction to Paleoclimates, G&G 402/602 . This is a graduate and upper-level undergraduate course on paleoclimate. The aim of the course was to provide students with an introduction to interesting climate periods in the Cenozioc (past ~65Ma). It married geochemical analysis with climate modelling to create a more complete understanding of the climate system. I co-taught this course with Prof. Mark .
Theory of Climate, G&G 523/323. A graduate and upper-level undergraduate course on climate dynamics. I contributed two lectures on Ice Ages.
Physical Oceanography, G&G 535/335. A graduate and upper-level undergraduate course introducing students to basic concepts in physical oceanography. I contributed a lecture on Air-Sea interactions.
The Physical Science of Global Climate Change G&G 702. A graduate seminar class, whose reading material was working group I of the latest IPCC (intergovernmental Panel on Climate Change) report. I was brought in to provide expert knowledge in the later chapters on climate models and their projections.
|University of East Anglia, School of Environmental Sciences, November 2012 - "Measurement and mechanisms of a structural climate change in the Early Pliocene" - in the Atmosphere, Ocean and Climate Seminar Series|
|University of Nottingham, Geography, November 2012 - "Structural climate change and the Early Pliocene" - Physical Geography Seminars|
|London Palaeoclimate Group, November 2012 - "An Introduction to PMIP3"|
|University of Edinburgh, School of GeoSciences, November 2012 - "Lessons from the warm Early Pliocene" - in the Global Change Seminar Series|
|Imperial College London, Physics, October 2012 - "Structural Climate Change" - in the Space & Atmosphere Physics Seminar Series.|
EGU Spring Meeting, April 2012 - "Can inter-ocean gateways explain long-term cooling since the early Pliocene?", EGU2012-5484, Poster in Session CL4.2/OS1.3
Also presented at Palaeoclimate Modelling Intercomparison Project, Phase 3 Workshop at Crewe, May 2012
University of Bristol, Geography, April 2012 - "Equatorial Temperature Gradients and Human Evolution"
Also presented as subsidiary talk at Brown University, March 2012
Brown University, Geological Sciences, March 2012 - "Beyond conventional climate sensitivity: understanding early Pliocene warmth"
Also presented at University of Exeter, College of Engineering, Mathematics and Physical Sciences, May 2012, in a modified form.
|University College London, Geography, November 2011 - "Ice Age Tropical Cyclones" - in the Physical Geography Seminar Series|
|University of Massachusetts, Amherst, Geosciences, June 2011 - "Comparing hypotheses for Pliocene tropical warmth"|
|University of Southern California, Earth Sciences, April 2011 - "Better climate predictions using hindsight"|
|AGU Fall Meeting, December 2010 - "The relative role of temperature gradients in the Pliocene climate", PP11G-03, Invited contribution to the session The Early Pliocene Warm Period as an Analog for Future Warmth.|
|AGU Fall Meeting, December 2010 - "Tropical Cyclones at the Last Glacial Maximum" Poster in session GC51G|
|Luncheon with the Postdocs, Yale Geology & Geophysics, April 2010 - "Vertical Mixing and the Ocean Circulation"|
|Ocean Sciences, 2010 - "Extratropical Hurricane Mixing and the Equatorial Cold Tongue", PO45W-04 in the session Theory and Modeling of the Equatorial Ocean. Also presented at the Department of Energy meeting in Gaithersburg in April 2010.|
|AGU Fall Meeting, 2009 - "Understanding Weak Low-Latitude SST Gradients and the Ocean Warm Pool Expansion in the Early Pliocene", PP11G-08 in the session The heat is on: past, present and future climate change in the Indo-Pacific warm pool.|
|University of Michigan Geological Sciences, Seminar, November 2009 - "Tropical Cyclones and the climate of the Pliocene"|
|Ocean-Atmosphere Energy Transport workshop, Caltech, November 2009 - "Extratropical Mixing, Ocean Temperatures and Heat Transport". Poster|
|Graduate School of Oceanography at University of Rhode Island, Invited Seminar, July 2009 - "Implications of the Vast Pliocene Warmpool"|
|Yale's Atmosphere, Ocean and Climate Dynamics group, March 2009 - "Temperature Gradients and Glaciation"|
|Yale's Atmosphere, Ocean and Climate Dynamics group, October 2008 - "The Curious Case of the Pliocene Climate"|
|Pliocene Model Intercomparison Workshop, June 2008 - "Greatly Expanded Warmpool and the onset of Glacial Cycles". Poster|
|Pliocene Model Intercomparison Workshop, June 2008 - "Greatly expanded warmpool, permanent El Nino and weaker Hadley circulation in the early Pliocene". Oral presentation given on behalf of Alexey Fedorov|
|AGU Fall Meeting December 2007 - "Permanent El Nino Conditions and the Meridional Expansion of the Tropical Ocean Warm-Water Pool in the Early Pliocene: Modeling Global Impacts with an Atmospheric GCM". Poster: PP43C-1531|
|Luncheon with the Postdocs, 2007 - "Ensembles, Uncertainty and Climate Projections"|
|Departmental Seminar, Uni. of Reading, June 2006. "Ocean Model Uncertainty"|
|Chapa Club 2006 - "Spatial Patterns of Climate Change in HadCM3" This presents the ensemble mean patterns from my perturbed ocean physics ensemble. The results are the average of year 61-80 from an 1% increase in carbon dioxide, so are centred on the time of CO2 doubling. It has a useful list of references for HadCM3 and climate change in it.|
|AGU Ocean Sciences, 2006 - "Incorporating and Quantifying Ocean Uncertainty in Ensemble Climate Prediction", OS52P-05 in the session on Ocean Convection, Heat Transport and Storage, and Climate.|
|Reading University's Ocean Research Group 2nd February 2006 - "The Relative Certainty of Ocean Parameters"|
|Royal Meteorological Society biennial conference, 2005 - "Including Ocean Model Uncertainties in Climate Predictions"|
|Departmental Poster Session, October 2005 - "The effect of Isopycnal Mixing in HadCM3"|
|Chapa Club October 2005 "Opal Fruits: made to make your mouth water"|
|Earth System Sciences Summer School, September 2004 - Ocean Model Uncertainty I created this early on, and it describes why ocean model uncertainty exists.|
PhD research students
Currently no PhDs being undertaken
- 2013 Sarah Cripps ongoing
- 2013 Tino Kretschmer ongoing
- 2013 Kanhe Wang ongoing
- 2012 Heidi Richardson The effect of disturbance on the bottlenose dolphin (Tursiops trucatus) in Cardigan Bay in Wales