Whether the warming is part of a natural cycle or anthropogenic will make no difference to us in the case of phytoplankton. Drastic reductions in their populations would cause major changes throughout the biosphere that I'm not so sure humans would be able to cope with successfully.

 

Thanks for the link Mike. The 2001 Climate Change report was very interesting. I will spend more time with it. Sorry I'm still not sold on your conclusion, despite the use of capital letters in "no doubt." While you seem to dismiss the "nobody really knows and anything is possible" crowd out of hand, there seems to be quite a bit of valid data to suggest the merit of that argument too.

 

Defining global warming in terms of the atmospheric temperature skews it toward the atmosphere; what's happening out there is that the entire system (air, water, land) is warming up. Because each component has its own thermal inertia, they respond at different rates -- the oceans (which serve the climate system as a sort of flywheel) are warming more slowly but their response to the greenhouse forcing is measurable.

Until recently, this atmospheric-centric definition has been used by the "contrarians" (as the energy-financed crowd has come to be called) to confound the issue, because one of the puzzles has been how to resolve apparent differences between computer simulations and satellite-derived inferences of upper-air temperatures. That's now becoming resolved, though (more sophisticated inferences) -- indeed, every issue that the contrarians have raised has been shown to be, in reality, a non-issue.

Our carbon emissions, bolstered by our emissions of other greenhouse gases, are warming the Earth up. Not a huge amount, and not instantly. But it's happening.

So, as I noted before, the question is whether we should be worried about it. That's something for people to debate, as different people have different comfort levels with different sorts of risks.

For reference, my credentials on the matter are in my CV, here. HPH

 

Well, lets explore this further. Are you saying that all (or most, or some) active researchers believe the current trend will continue ever upward (if the current conditions continue) and will never reverse for any period of time beyond a day (or week or month)? When I look at the very general 100 year graphs, it seems that just 20 or 30 years ago a 30 or 40 year cooling period came to an end. Are you saying that won't ever happen again, absent some change?

 

Ok, one further clarification then. By atmospheric, I was referring to air temps at or near the surface of the earth rather than upper levels of the atmosphere. I understand the temps in the upper levels have risen much less.

Based on your back ground, please tell us about the data and why you believe it to be valid.

 

Do you happen to know what the associated changes in salinity are projected to be?

 

[QUOTE=Legal Bill,Nov 9 2005, 07:21 PM] Thanks for the link Mike.

 

Nope. Due to my job requirements I'm more familiar with atmospheric effects than ocean effects. But the salinity change is likely to be quite significant.

 

If I understand you correctly, you are wondering whether most researchers in the field are convinced that the data we have seen so far is a long term anthropogenic shift, rather than a cyclical or random shift. And the answer is "yes".

A decade or so ago, the answer would have been "the jury is still out". But inside the research community, the jury has come in and the verdict has been read and announced. You know this by looking at the journals and seeing what people are choosing to work on and choosing to publish. There is no one seriously working on "is anthropogenic climate change real?" any more, because after enough people come to the same conclusion using enough different sources of data, it ceases to be interesting.

 

Mike's comment about preponderance of data and his jury metaphor fit the situation perfectly.

Acceptance of a hypothesis by individuals and by a community consensus is based on persuasive evidence (belief is for religion) generated by well-grounded, repeatable research results. In the case of global warming, the fundamental hypothesis (which is, in essence: increased loading of the atmosphere with greenhouse gases will decrease emission to space of Earth's heat and thus warm the planet up) has been validated by theory (in the form of simple, mechanistic explanations of the phenomenon), experiment (using a wide variety of detailed computer simulations based on solid physical principles), and observations (not only of temperature, but also of everything else linked to climate).

The popular press, either in its ignorance or in its zeal to create controversy, has given far more credence to the contrarians than the scientific community ever did, and perhaps that's why lay people remain skeptical. But now, scientists are interested in the next set of issues: How much warmer (and: wetter or drier?)? Where? When? What implications are there for the biosphere? How about those counter-intuitive changes I mentioned?

The IPCC reports mentioned previously come out every 5 years or so; the third one (2001) runs hundreds and hundreds of pages in three volumes, and the fourth one (due out soon) will probably be fatter. And they build on each other (like all science does), in the sense that the later volumes focus on unresolved issues rather than re-hashing old stuff.

Unlike more esoteric fields of study (quantum physics, say), climate is something that everyone has a taste of, and instant experts abound ("Hell, it was colder than ever at my place last winter! What's this global warming crap, anyway?"). Yet it is a vibrant scientific research area, well funded, involving hundreds of scientists across the world. Every little thing (including the urban heat island temperature record bias) gets picked apart in great, gory detail. And because this research is all under the spotlight, it's done carefully, with that in mind.

So the question of whether we should worry or not is the relevant one. Like a famous movie cop said: How lucky do you feel? HPH