Early white paper draft version- October 2013
This preliminary draft is intended as a consultation document.
Comments/edits welcome. Please do not use or cite.
Theme 6: Interconnections between ocean biogeochemistry and stratospheric chemistry
Co-authors: Eric Saltzman and Roland von Glasow
1. Brief statement defining the theme:
Reactive gases emitted from the sea surface are transported to the stratosphere in the tropics, where they can
influence photochemistry and chemistry and catalytically destroy ozone. The chemical composition and
spatial/temporal distributions of these emissions, and the biogeochemical factors controlling them are not well
understood. The goal of this theme is to provide a basis for understanding how the oceans impact stratospheric
chemistry and how future changes in oceanic ecosystems will influence stratospheric ozone.
2. The scientific and societal basis justifying research on this issue. Why is it critical and why does it
need to be done now? What is the end goal? Why is international coordination required?
Stratospheric chemistry is of great importance to the Earth system because of its role as a protective shield
against harmful ultraviolet solar radiation and its influence on Earth’s energy budget. Over the past century,
industrial and agricultural emissions have altered stratospheric chemistry by the emission of chlorofluorocarbons
and other halogenated chemicals, methane, nitrous oxide, and sulfur dioxide. There has been progress
controlling the emissions of some of these compounds through international agreements under the international
Montreal Protocol and others are discussed under the Kyoto Protocol and other frameworks. However, the task
of returning stratospheric ozone to a natural or preindustrial state is complicated by other ongoing environmental
changes, which have the potential to alter biogeochemical emissions of stratospheric ozone-depleting chemicals.
For example, large-scale changes in oceanic ecosystems are anticipated over the coming century, driven by the
multiple stressors of climate change, ocean acidification, and anthropogenically-driven changes to nutrient
cycles. These changes may affect the emissions of ozone depleting substances from the ocean surface. As a
consequence, predicting the future evolution of stratospheric ozone during the coming century involves
understanding the oceanic emissions of ozone-depleting substances and how they will evolve.
Understanding the oceanic impact on stratospheric chemistry is a multidimensional problem, involving ocean
ecosystem dynamics, surface ocean biogeochemistry, and atmospheric chemistry and dynamics. The research
requires interaction across a wide range of disciplines – from phytoplankton physiology to photochemistry,
meteorology, oceanography, and climate. The observational requirements include coordinated observations in
the oceans and atmosphere, remote sensing, and coupled ocean/atmosphere modeling. The need for
international coordination is compelling in order to plan, and execute major field programs, involving both
oceanographic and atmospheric research platforms, and to facilitate communication between the various
communities engaged in the work. In terms of societal need, we require not only a scientific understanding of the
problem, but policies capable of responding to the factors coupling the two issues of stratospheric ozone and
climate change.
3. Background – major scientific concepts, key prior work defining the issues:
It is well established that halogen atoms (Cl, Br) released from halocarbons lead to the catalytic destruction of
stratospheric ozone. The majority of the chlorine and bromine in the stratosphere is derived from anthropogenic
emissions of long-lived compounds which are long-lived in the atmosphere, and which are controlled under the
Montreal Protocol. However, a portion of stratospheric ozone depletion can be attributed to the emissions and
transport of so-called “very short-lived substances” or VSLS. These are defined as trace gases whose chemical
lifetimes are comparable to transport times in the troposphere (<0.5 years). Hence, they are non-uniformly
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distributed in the lower atmosphere and their effects on the upper atmosphere are highly sensitive to their
chemistry and transport, and the location of their emissions. VSLS include both anthropogenic and natural
compounds.
It has been shown that the tropical oceans play a role in the delivery of VSLS: 1) a wide range of volatile
halogenated and sulfur-containing compounds are produced biologically and photochemically in seawater and
are released to the marine atmosphere, and 2) some biologically productive waters occur in tropical regions with
strong vertical uplift, where air is entrained into the upper troposphere/lower stratosphere.
4. Approaches – what will it take to make substantive progress on the issue? What will be achieved in
the 10 years of Future SOLAS?
 Field observations of emissions, and atmospheric distributions of stratospherically active compounds and
precursors over oceanic, most importantly the Indonesian “maritime continent” and tropical western Pacific
where strong uplift occurs.
 Laboratory, mesocosm, and field studies of the mechanism of production of such gases and the processes
that control their emissions from the sea surface, and investigation of how future changes in ocean nutrients,
pH, etc. will impact these processes at the organism or ecosystem level.
 Atmospheric chemistry field, laboratory, and modeling studies of the transformations of VSL compounds after
emission.
 Modeling studies examining the impact of oceanic emissions on stratospheric chemistry and the linkages
between climate and the biogeochemistry of these compounds.
5. Community readiness – is there an existing community engaged on this issue? Are there institutional
or other barriers to progress? Is infrastructure or human capacity building required in order to achieve
the goals?
This research requires collaborative interaction among communities which historically are trained in different
institutions, attend different scientific conferences, and utilize very different vocabularies. These include
microbiologists, biomolecular chemists, chemical oceanographers, tropospheric/stratospheric chemists and
dynamicists, and climate scientists. Progress in this area will require scientists who share a common
understanding of the complex interconnections between the ocean, stratosphere, and climate. The atmospheric
chemistry and dynamics communities are fairly well linked via joint consortia (e.g., the recent EU-funded SHIVA
consortium) and assessments, most prominently the WMO Scientific Assessment of Ozone depletion. New
efforts are needed to extend these linkages to the other communities listed above.
6. External connections – what partnerships are required in order to achieve the goals? What
mechanisms will be used to accomplish the interactions?
Important partnerships include the IGAC/SPARC Chemistry-Climate Model Initiative (CCMI), the SPARC
Stratospheric Sulfur and its Role in Climate (SSiRC).
7. Sustainability – articulate relationship (if any) between this project and the FE goals of Global
Development and Transformation Towards Sustainability.
Maintaining a healthy stratosphere is one of the most fundamental requirements of a sustainable society. The
costs of stratospheric degradation include human health risks, damage to oceanic ecosystems and food web,
potential changes in genetic mutation rates, damage to agricultural crops and livestock. In addition, there are
many interactions between stratospheric ozone and other elements of the climate system. There is a direct
societal interest in understanding the risks associated with various forms of human activity. The Montreal
Protocol was an outstanding example of how dramatic environmental change (i.e. the Antarctic ozone hole)
galvanized nations society to successfully cope with an urgent global environmental issue. The longer-term
climate/ozone interactions discussed here have the potential to change the “baseline” of ozone depleting gases
which the Montreal Protocol seeks to regulate. Furthermore, some proposed geoengineering schemes involve
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changing surface oceanic biogeochemistry. It is important to have a multidisciplinary community capable of
assessing such scheme for the full range of possible environmental consequences.
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