BAMS 1413 B

Peter D. Blanken, Assistant Professor

Editorial Board, Bulletin of the AMS

Department of Geography & Program in Environmental Studies

University of Colorado at Boulder

260 UCB

Boulder Colorado 80309-0260

Email:

Dear Peter,

I have finally reviewed the lengthy manuscript by Miller et al. (AMS BAMS 1413, Potential Feedbacks between Pacific Ocean Ecosystems and Interdecadal Climate Variations) that you sent me in late February. My overall recommendation is Accept with little revision. This manuscript covered material that is actually fairly distant from my field of interest and therefore I found much of it difficult to read and digest. The other reviewers or editors will have to decide if there is too much detail here. It seemed to me that the take home message was that while theoretically there could be biological feedback to climate, there is precious little observational evidence and not likely to be for decades to come. Nevertheless, this is a fascinating subject that deserves broader recognition. Within much of the marine biology community I think the very notion that biology might influence interdecadal climate variability would be initially dismissed as impossible. Let’s hope they are somewhere referred to this paper should it be published in BAMS.


General Comments

This a very lengthy review paper that covers much ground – in varying detail – and is not a simple read. At the heart of this paper is the premise that there are two potentially important pathways by which “ecosystems” may influence climate on interdecadal time scales. One is through a change in ocean surface albedo due to changing concentrations of phytoplankton. Increased phytoplankton concentrations decrease albedo, increases absorption of solar radiation and warms the ocean surface. The other is via a change in dimethylsulfide fluxes associated with phytoplankton. The amount of intracellular DMSP ( a precursor to DMS) varies among phytoplankton species. The effect of DMS fluxes is primarily on clouds and the atmospheric radiation budget. The paper is extremely well written and organized and appears to be highly polished.

There is not a great deal of observational evidence provided for either of the potential major mechanism; this paper is perhaps more of a detailed thought exercise.

With the exception of what I consider to be excess detail on pages 11-13, the relative length of the sections - intro, review, mechanisms, suggested research and conclusions is proper.

The figures are probably the weakest part of the manuscript. Figures 1 and 8 seem overly cartoonish and could be upgraded. There are no figures showing simultaneous interdecadal variation in biology and climate which is the topic of the paper.

Specific comments

p. 9 – What is the GBC journal?

p. 11-13, This much detail about modeling problems really bogs down the paper. Perhaps it could be shortened or moved to an Appendix. For example, the length and level of detail in part ii of this section, Phytoplankton effects on DMS fluxes, is just right.

p. 15/16. The math here seems to differ with the conclusion. A change in chlorophyll concentration from .03 to 30 is a 1000 fold change and this would change reflected solar flux by 1 W/m^2. This does seem somewhat negligible since a 1000 fold change in average concentration is highly unlikely.

p. 16 What is Tg S/yr? Terragram? How about a definition.

Figures 3&4 - The symbols for N. Hemisphere, S. Hemisphere, Global should be the same for the two figures.