An Introduction

The Charles Paleoceanography Group at SIO uses the geological archives of recent climate change and carbon cycling to address several prominent issues of "global change": How sensitive is the Earth's climate system to disturbance? Is there a relationship between the variability of climate and the average state of climate? What are the principal mechanisms for instability in both cold and warm climates? I am interested in any medium that registers and preserves a climate signal, but the group mainly uses a few analytical tools (primarily, the stable isotopes of oxygen, carbon and nitrogen) to reconstruct climate variability on timescales ranging from ice age cycles to interannual fluctuations. Students (and post-docs) in the lab are encouraged to develop and carry out their own projects (click on their individual links for more information), making full use of the diverse resources available at SIO.

One steady theme for the group has been the coral record of interannual climate variability. In the mid 1990's we spent a number of years exploiting the record from living corals and sponges. After this initial period of exploration, we have since moved on to fossil material that spans greater intervals of time, and graduate student Kim Cobb made this material the subject of her doctoral dissertation (completed in 2002). After Kim graduated, she and I have further developed the record of fossil coral from the Line Islands (Central Pacific), and we are aiming to arrive at a continuous reconstruction of the El Niño/Southern Oscillation phenomenon, at monthly resolution, for at least the last 1100 years. Looking ahead, I am trying to work along analogous lines to investigate the coupling between the Indian Ocean and the South Asian monsoon throughout the Holocene, again making use of fossil coral material from various atolls throughout the Indian Ocean .

Another current theme is the deep sea sediment record of the ocean's large scale overturning circulation. This circulation has often been implicated in the abrupt climate changes that punctuated the late Pleistocene epoch, but the explanations for these dramatic climate events will remain largely speculative until there is a legitimate picture of "what happened when" in the deep ocean. Current student Jenna Munson's work with the radiocarbon record of the deep South Atlantic, we hope, will constitute as yet the most complete vertical profile of the influence of Antarctic Intermediate Water and North Atlantic Deep Water over the last deglaciation. Inspired by Ralph Keeling's theoretical arguments, Jenna's work grew out of my long standing collaboration with Niall Slowey at Texas A+M. She is analyzing a suite of cores collected on our joint cruise in 2003.

Another theme that has carried through from my dissertation work involves the cycling of carbon over the Pleistocene ice ages. The mystery of what caused the large natural, glacial-interglacial fluctuations of atmospheric carbon dioxide has endured for over 20 years, but if the enigma could be solved, this advance would lead directly to a refined assessment of how (and at what rate) the ocean might soak up anthropogenic CO2. Our lab's contributions, along with various collaborators, have essentially dealt with the timing of Southern Ocean record of nutrient cycling and the biological pump of carbon. The basic principle is that all the different proposed mechanisms for reducing atmospheric CO2 during the ice ages make unique predictions for the sequence of events in the ocean/atmosphere system. The general problem has been especially difficult to "nail" for various reasons, and there are still plenty of discoveries to be made! Current activities include collaboration with Professor Devendra Lal on the trace metal signature of marine diatoms. Also, graduate student Patrick Rafter is attempting to disentangle the various imprints on the marine nitrogen isotope budget of the equatorial Pacific.

Finally, a significant fraction of my own published work falls in the category of general Southern Ocean paleoceanography. This work reflects my collaboration with David Hodell at the University of Florida and former SIO graduate students Graham Mortyn and Ule Ninnemann. My group's papers essentially describe the series of observations that arose from Ocean Drilling Program Leg 177. The main strategy behind this drilling campaign was to collect a transect of sedimentary sequences from sites spanning the potential latitudinal excursions of the frontal boundaries and seasonal sea ice cover. As a result of these efforts, the sediments collected yield constraints on the dynamics of the surface Southern Ocean over a variety of timescales. We are not finished mining these sequences for various purposes, but, along with a host of other collaborators, we have already started looking ahead to the more challenging prospect of acquiring analogous sequences from the Pacific sector of the Southern Ocean (perhaps by 2008).

April 2008

The ESYS 10 class is over, but there was no Spring Break for the Charles Lab. After grading the final exams from ESYS 10, Patrick prepared to give a talk at USC and Chris prepared for his next class--Paleoclimatology (a graduate student level class at SIO).

In other news, we just noticed that Lydia Roach's upcoming cruise to the Santa Barbara Basin is on the UNOLS website and here's a screen grab and link of it:

March 2008

Chris and Patrick are still immersed in their ESYS 10 class, Patrick continues his months of work analyzing sediment N isotopes (slow going, but good data!). Lydia travels to Minnesota this month with her newest Swamp Lake sediment cores. However, the most important event in the Charles lab this month was Jenna's defense! Here are some photos:

Jenna and her committee

Jenna waits, while Chris introduces her

February 2008

Chris is teaching Introduction to Environmental Systems (ESYS 10) this quarter and Patrick is TA'ing. Jenna is finishing up her thesis and getting ready to defend next month. Lydia takes a trip to Cal Tech to measure H isotopes in her Swamp Lake cores and Danny is culturing diatoms and running coral samples on our mass spectrometer.

January 2008

There is a lot going on in the Charles Lab this quarter--Chris is teaching ESYS 10 (Intro. to Environmental Systems) and Patrick is the teacher's assistant. To find the syllabus, click here (or over to the left).

Here's a nice photo of the science party from the last cruise (missing Arjan and Peter):

December 2007

Lydia is giving a talk at the fall AGU meeting in San Francisco. Everyone else continues with their own work at home and we finally receive the sediment cores from the last cruise!

October/November 2007

The Charles Lab is out to sea! We are in the middle of the Indian Ocean--our objective is to retrieve fossil coral from the outer Seychelles Bank. Read the whole story here.

September 2007

We've just experienced a major heat wave in southern California, but today it feels like autumn is just around the corner and technically speaking, it is approaching quickly.

The Charles lab is very, very busy in the upcoming months. Chris is travelling around the world and preparing for our research cruise this October in the Arabian Sea. Meanwhile, Lydia has a second expedition to Yosemite National Park.

Patrick is also getting married.

Here's a photo from last year's Yosemite expedition:

July 2007

Summertime here at SIO is somewhat quiet with many groups out to sea or out in the field. The Charles lab's upcoming cruise isn't until this fall, so we've been busy working in the lab or writing, writing, writing.

May 2007

As we are approaching the summer, we are all busy in the Charles lab. Lydia is creating thin sections from her Swamp Lake freeze cores, Jenna is beginning to write her thesis, Patrick is running sediment samples for N isotopes here at SIO, and Danny is culturing diatoms! A very diverse group.

January 2007(update)

New photos from Chris' pursuit of Porites coral in Sri Lanka:

Discussing the coral

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We also just received some older images (from 2005) of former Charles Lab student Kim Cobb drilling coral underwater:

Kim taking a break from drilling

Kim drilling and Jordan watching

January 2007

A new year for the Charles Lab and like the last, it's a busy one. Chris will be teaching a class entitled Introduction to Environmental Systems (ESYS 10) this quarter (link here).

December 2006

For Earth Scientists, December means the American Geophysical Union's Fall Conference in San Francisco. Most of the Charles Lab was in attendance and Jenna was presenting her research. Jenna's talk was great and afterward she fielded several good questions.

October /November 2006

The Roach Yosemite Expedition went off without any problems (except for some blisters due to lots of hiking). Here's some photos for your enjoyment:

The Expedition Group on the luxurious R/V Roach

The object of their desire--the FREEZE CORE!

I'm sorry to say that I forgot to put up a photo of Danny Richter growing his diatoms for the last update--here it is:

August / September 2006

It was busy couple of months for the Charles Lab. Danny was culturing diatoms (they are doing much better than the plants in the lab), Jenna and Lydia flew off to Lawrence Livermore National Laboratory to analyze foraminifera for radiocarbon, and Patrick flew to Princeton, New Jersey to analyze the Nitrogen isotopic composition of Nitrate in the equatorial Pacific (at the Sigman lab). Danny did not get to fly off to anywhere exotic like Patrick, but he has a lot to do back here at SIO--he organized the new student welcome party on the SIO pier and he is helping to organize the SIO Geology, Geochemistry, and Marine Chemistry Seminars.

Patrick and Lydia also drove to Flagstaff, AZ where they saw plenty of cactus:

Next month (October) will see the Lydia Roach Scientific Expedition to Swamp Lake (in Yosemite National Park). Stay tuned for many pictures!

June/July 2006 (updated)

Well, the newest member of the Charles Paleoceanography Group just finished his first year of graduate school--here is Daniel Richter:

Congratulations Danny! Expect a biography from him soon (now that he has no more excuses!).

June 2006

It's summer time in La Jolla, California, which means... June Gloom--overcast skies that hug the coastline. You can see an interesting discussion on this meteorological condition on the SIO Climate Research Division's June Gloom website.

The Charles Lab has been working hard with Jenna and Patrick writing papers, Chris continuing his isotopic analyses of coral, and Lydia picking forams for radiocarbon analysis. Patrick also just received the SIO Whole Earth Society grant and he would like to thank this organization for their support. Finally, Daniel Richter (profile in development), who is co-advised by Chris and Devendra Lal, received a National Science Foundation Graduate Student Fellowship! Congratulations Danny!

April 2006

Once again, Lydia makes the Charles Lab News--she gave her first talk at the PACLIM Conference, which focused on climate variability of the eastern North Pacific and western North America. It sounds like it went well.

As for the rest of the lab, Jenna is writing up her first paper and so is Patrick. Patrick also visited the Sigman Lab at Princeton to analyze nitrogen and oxygen isotopes of Nitrate.

March 2006 (updated)

Our very own Lydia Roach was featured on the Scripps homepage:

Here's another from the SIO Alumni page:

By the way, Lydia isn't an alumnae yet.

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We've added some new photos to the Charles Lab website and now we are all much better looking.

Also, check out the photos from the Line Islands trip with Kim, Jordan, and Kristy here.

January/February 2006

A lot going in the Charles Lab recently. Chris recently returned from Sri Lanka where he was on a teaching fellowship. Lydia received a grant from the California Space Institute and Patrick received a fellowship from the Ocean Drilling Program. Patrick also discussed the first results of his thesis at the Ocean Sciences conference in Honolulu, Hawaii. Jenna is busy writing her first paper.

November/December 2005

Welcome to Kristina Dahl, the new Post-Doc at the Charles Lab. Kristy comes to SIO from Woods Hole and we'll have a personal page up for her soon. Until then, check out her WHOI webpage here.

Chris is in Sri Lanka for a few months to teach and search for new coral skeletons.

August/September 2005

The Charles lab's technician Jordan Watson has joined former student, now Georgia Tech Associate Professor Kim Cobb along with our future Post-Doctoral researcher Kristina Dahl on a trip to collect more coral skeletons from Fanning and Christmas islands in the tropical Pacific. A short explanation of their trip can be viewed here on the "Line Islands Expedition" website.