Question from a non-scientist

[magic_8ball]

A question just occurred to me, and since the only scientist I know in RL is in a WAY different discipline, I figured I'd post here and see if anyone could give a quick answer. (I read the community guidelines and no, this isn't for homework or anything. Also, I apologize if I shouldn't be posting at, since I'm not a scientist. I'm just a

Comments

[jennaflower]

So, volcanism can have an effect on global warming (or more accurately, global climate change), but not in the way that you've hypothesized (at least as far as I know). Volcanic gases include CO2, which can add to global warming, but in a much lower amount than human activities that produce CO2. On the other hand you have SO2, sulfur dioxide, which can form sulfuric acid aerosols in the stratosphere which can actually cool climate because they absorb solar radiation and scatter it back to space. You also have chlorine from hydrochloric acid, which destroys ozone

[ammonoid]

increase in global ocean temperatures will lead to thermal expansion of water, causing sea level to rise

I was fairly sure this was due to melting of polar ice and glaciers, not from thermal expansion of water. After all, water does not expand or contract much from temperature.

[surferrosa14]

It is from both. It doesn't expand or contract much but it does change slightly. When you look at something as vast as the ocean, this is effect is no longer negligible.

[magic_8ball]

Related question -- melting the polar ice cap would dump countless millions of gallons of fresh water into the ocean, changing the salinity factor and (presumably) raising the freezing temperature of the northern seas. Would that maybe facilitate re-freezing?

[jennaflower]

Interesting point. So then you'd have a negative feedback.

[surferrosa14]

Yes. There are so many feedbacks to consider. I don't know much about this one, but at my university there is a lot of active research on the subject of the ice-Albedo feedback. This feedback has a warming effect. It involves the loss of reflectivity with loss of ice, and it makes the predictability of the melting far more uncertain

[surferrosa14]

One of my coworkers just pointed out that "Field Notes from a Catastrophe" was written by a journalist. He says it is probably worthwhile reading but just be careful of what you take away from it, since it wasn't written by a scientist. I plan to read it, or at least attend her discussion of the book.

https://go.washington.edu/uwaa/events/2007commonbook_kolbert/details.tcl

[cassiopeia13]

Wouldn't that cause a drop in global temperatures over land? If the freezeing temp changed and more ocean water froze???

[magic_8ball]

Hmm

[cassiopeia13]

According to Al Gore's movie (which had lots of holes, I'll agree), He said that when the last ice age happened, North America froze. When things started to thaw, the ice that had melted in the middle of the US, flooded into the ocean, causing the atlantic waters saline levels to lower, and since all that frozen water went rushing into the ocean, pushed Europe into an ice age for another 900 years.

Sounds plausable, which is why I'll say "Yeah okay I'll go with that"

Something about ocean currents and all that jazz. Now I know there's a strong current going downt eh coast of Cali so if frozen fresh water was poured out of Alaska/Canada and the artic (antartic? I can never remember which one is on top) wouldn't that do something to the Pacific?

Wonder how long it takes for water to cycle the globe.. hmmm.... aaah questions!

[adrinna]

What's interesting is that thermal expansion is expected to have a much larger effect in the long run (over something like melting).

[jennaflower]

Actually, interestingly enough, thermal expansion of water does have a contribution to sea level rise, and most global climate models incorporate a term for thermal expansion. I did not mean to imply that thermal expansion was the main reason for sea level rise, only that it makes a contribution. Yes, obviously melting of polar ice and glaciers are major contributions, but so are other factors, including adding less dense freshwater from glaciers to more dense (i.e. occupying a smaller volume), salty ocean waters. The reason I mentioned thermal expansion was because the question asked referred to matter expanding due to an increase in temperature.

I am not familiar with the exact contribution of each factor, though a quick literature search seems to show that the contribution of thermal expansion to sea level rise is still be studied (e.g. Meehl et al., 2005, Science, vol. 307).

:-)

[adrinna]

I seem to recall the latest IPCC report showing that the thermal expansion contribution was projected to be the biggest (bigger than melting!). I'll try and dig up that table.

[cassiopeia13]

More damage would be caused by land ice falling into the sea than ocean ice as far as raising sea levels go. Like if you start off with a glass full of ice and pour water into it, when the ice melts the level of water stays relatively the same, but if you pour water into a glass THEN add ice, the water level goes up