The health of our
climate is crucial for the comfort of life on Earth. The climate is
ever-changing and influenced by natural and anthropogenic factors. Over the
last two centuries, human interference has changed climate in ways that are
unprecedented and the phrase ‘Climate Change’ is now familiar to common man.
Accumulation of human induced greenhouse gases in air has heated the atmosphere
and oceans. Our altered climate is already having negative impacts on the
health and socioeconomics of various populations. There is an urgent need to
reduce human interference and explore possible remedial measures to overcome
the ill-effects of global change.
Aerosols and clouds play
an important role in reducing the amount of solar radiation that reaches the
Earth. The clouds help by acting like a ‘mirror’ reflecting part of the
incident solar radiation. Earth would be far hotter without this cooling
mechanism. Clouds are formed by the aggregation of moisture and aerosols. The
moisture comes from evaporation and the released aerosols have both
anthropogenic and natural sources. Whilst industry is the dominant source of
the man-made aerosols, natural aerosols are released at the earth surface in the
form of dust and sea spray. Aerosols also form in the atmosphere from biogenic
gases emitted at the Earth's surface. Dimethylsulphide (DMS) is perhaps the most
important marine biogenic gas that contributes to white clouds in the
atmosphere and facilitates higher reflectivity and cooling.
The role of DMS in
climate was first highlighted in the 1970’s, but we still don’t completely
understand its mechanisms of formation and fate. DMS is derived from a major
algal precursor dimethylsulphoniopropionate (DMSP). The biological reasons for
DMSP production by phytoplankton are not clear although several theories on its
role as osmolyte, anti-grazing compound, anti-bacterial and anti-oxidant have
been proposed. Similarly, the fate of DMSP in seawater is important because
decomposition doesn’t always lead to DMS formation. The biogenic DMS undergoes
transformations before forming the sulphate aerosols in air. The hygroscopic
sulphate aerosols condense along with other constituents in atmosphere leading
to the formation of condensation nuclei (CN) and cloud CN (CCN), which are
important in formation of clouds and rain.
Despite the relatively
simple schematic that biogenic DMSP leads to the formation of DMS, oxidation of
which will lead cloud droplet formation, there is substantial complexity in the
picture between the processes and intermediate compounds produced in cells of
organisms in seawater and particles/clouds in atmosphere. Our current level of
knowledge already represents significant progress, but a lot needs to be done
before we claim that the biogeochemical cycling of DMS is understood in the
context of our changing climate. Understanding these processes better and
modelling their role in the Earth’s climate system are the challenges that the
scientific community has accepted.
One of the major
mechanisms for stimulating research on the production of DMS is the periodic
review of research progress. Realizing this, the DMS(P) community has been organizing
international meetings in a series. The ‘International Symposium on biological
and environmental chemistry of DMS(P) and related compounds’ have been held
roughly once every four years: the 1st Symposium in Mobile, USA (5-8 June
1995); the 2nd in Groningen, The Netherlands (25-28 August 1999); the 3rd at
Rimouski, Canada (26-28 September 2002); the 4th in Norwich, UK (2-6 May 2006).
The 5th in the series be being organised at the National Institute
of oceanography, Goa, India.
The scientific
objectives of the 5th International DMS(P) Symposium are to:
1. Facilitate world ‘DMS(P)
and related compounds’ community interactions and promote related research.
2. Review the recent
advances on DMS(P) and related compounds biological and environmental research.
3. Document the advanced
understanding in a special issue of a reputed journal, and
4. Identify new areas
for DMS(P) research with particular focus on relating phytoplankton to climate.
The symposium will
comprise invited talks, offered talks, poster presentations, and open to all
aspects of research related to the Symposium. The expected invited speakers are
well known experts in their fields, whose interactions will ignite the minds of
younger researchers. This will promote research on DMS and related compounds to
new heights and help in further understanding its relevance to biological and
climate processes. We fully expect the symposium to strengthen existing links
and facilitate the establishment of new links between DMS researchers and
institutions from various countries.
Special publications are important outputs for the
Symposium series. Special issues of peer-reviewed, international journals and a
book, have ensured that that ‘state-of-the-art’ research on DMS and related
compounds reaches a wide audience. The 1st symposium book was published by
Plenum Press (1996). The 2nd, 3rd and 4th Symposia contributions appeared in
special issues of Journal of Sea Research (2000), Canadian Journal of Fisheries
and Aquatic Sciences (2004) and Aquatic Sciences (2007), respectively. Discussions
are underway with Springer for publishing papers from the 5th Symposium in the
journal Biogeochemistry. We firmly believe the deliberations during our
meeting and the special publication end product will stimulate new links and
further research on DMS and related compounds.
