(Comments regarding the lack of a basic courtesy link now edited out.)
Your quote is from the first link below. The citation it references in indicated in the second link below. The referenced article itself is in the 3rd link below. Now for my comments.
First, this is a paper dated October 1992. You might consider the idea that there has been more recent work in the 22 years since. That paper has been cited by later work perhaps 140 times already. Ever bother to look and see what may have added to the picture since then? Consider the 4th link below, for one such example.
But let's just drop back to the 1992 reference. The significant uncertainties are discussed in a question/answer there:
Q: ? ? ?Given the uncertainties involved in the calculation of air-sea
? ? ? ? exchange of gases such as DMS, is it possible to assess by
? ? ? ? other methods the importance of natural versus anthropogenic
? ? ? ? sulfur emissions?
With the following response from the authors:
A: ? ? ?In our paper we discuss various approaches that have been
? ? ? ? taken to estimate the rate of emission of DMS from the oceans
? ? ? ? including models (Erikson et al. 1990, Thompson et al. 1990)
? ? ? ? and the use of observed concentration fields of DMS combined
? ? ? ? with knowledge of air-sea transfer velocity (Andreae 1986,
? ? ? ? Bates et al. 1987b). In addition measurements of MSA in
? ? ? ? atmospheric aerosols can be used to infer the emission of
? ? ? ? DMS into the atmosphere (J. Prospero, University of Miami,
? ? ? ? pers. commun.). Many studies (not reviewed in this paper)
? ? ? ? have investigated the emissions of sulfur from manmade
? ? ? ? sources. In all these attempts, an assessment is often made
? ? ? ? of the relative importance of the two sources, although the
? ? ? ? methodology used to calculate biogenic and anthropogenic
? ? ? ? sources are fundamentally different. The only consistent
? ? ? ? approach we are aware of, which has the potential to directly
? ? ? ? ascribe sulfur in the atmosphere to its major sources, is
? ? ? ? through the use of sulfur isotope signature measurements.
? ? ? ? The method relies on the sulfur isotope signature of fossil
? ? ? ? fuels being significantly different from that of DMS and its
? ? ? ? oxidation products. This approach shows great promise and
? ? ? ? is currently being investigated in our laboratory.
It's an interesting topic. DMS produced by plankton is a major source of sulfate aerosols. Sulfate aerosols come from both human and natural sources and they do play a role in the overall radiation balance on Earth, through a variety of mechanisms. These include direct and indirect scattering and absorption, at solar and terrestrial wavelengths. However, these aerosol effect uncertainties are very, very large.
What's actually a MUCH more interesting question is how AGW from human CO? releases can feed back through modification of plankton activity -- especially in polar regions where the impacts appear greater -- and the consequent DMS production to change the radiative balance. It's just one of many impacts where there is still yet interesting research going on. This one is fascinating, too.
I believe sulfate aerosols would have more impact if they could reach the stratosphere. But I don't think they'd survive the tropospheric transit time required to travel towards the equator to get upwelled there. Let alone stay long once arrived. I'll have to write someone and ask, though, now that it has crossed my mind.
Yes, like hydrogen sulfide, sulfur dioxide and many other sulfur compounds, dimethyl sulfide in the atmosphere will react with water vapor and oxygen to make sulfuric acid. Since dimethyl sulfide, and hydrogen sulfide are produced by microorganisms under anaerobic conditions similar to what produce methane, these compounds could partially cancel out the effects of methane.
But sulfuric acid is a component of acid rain, and it is doubtful that they completely cancel out the effects of methane. Methane may have ended glaciations in the past.
Methane and carbon dioxide during ice age
http://www.giss.nasa.gov/research/briefs...
Cyclops
< A review of the scientific literature, however, reveals the strength of this negative feedback is likely much larger than the IPCC asserts>
If DMS were a strong negative feedback, cloud cover would be increasing with increasing temperature.
Low cloud cover vs time
http://www.climate4you.com/images/CloudC...
Yes, there are likely countless feedbacks (both positive and negative) that have not been identified yet, and probably many that never will be identified. The climate and weather is a REALLY complex system.
http://en.wikipedia.org/wiki/CLAW_hypoth...
http://en.wikipedia.org/wiki/Dimethyl_su...
https://www.google.com/?gws_rd=ssl#q=Dim...
SO, yes, it has been proposed.
And it's also been proposed that it might have the opposite effect.
At the moment, until it can be shown to have any effect at all, I doubt that either side can claim it.
It is an organic compound produced by phyto-plankton
