5 ms·

Melting is a proxy for warmer waters. Water becomes less dense (e.g. expands) as it warms above 0C (a little bit less for salt water). When you have a volume th

Melting is a proxy for warmer waters. Water becomes less dense (e.g. expands) as it warms above 0C (a little bit less for salt water). When you have a volume the size of the oceans, a small increase is a big surface volume change.

nimchimpsky 9y ago
Eh ? Sea level rises are due to land based ice melting.
discoursism 9y ago
Edit: this paragraph is full of lies. -- There are a lot of things to be worried about with global warming, but I have never heard the density of ocean water listed among them. Water at 24 C is 0.002 less dense than water at 14 C. Since 10 C swings in global temperatures would long have caused catastrophes in other domains, I don't think we'll be much bothered by this small of a change in ocean density. Please enlighten me if I am incorrect. Edit: thanks, all. I stand corrected.
- teraflop 9y ago
  A 0.002 relative change in density is actually quite a lot, if you consider that the oceans are 12,000 feet deep on average.
- flukus 9y ago
  If I'm correct (not a hydrologist) 0.002 decrease in density translates to a 2M (~6 feet) sea level rise per KM of ocean. Some quick googling suggest that the average ocean depth is close to 4KM. So even small changes can have noticeable effect, particular when it's combined with other changes.
  - yters 9y ago
    I'd be interested to hear more on this. Is this warming uniform throughout the entire depth? Does the change in density impact the ocean uniformly or mostly on the top layer where the pressure is less?
    - flukus 9y ago
      Take everything with a huge grain of salt here, I'm far from an authority on any of this, some of it I don't really grasp myself. > Is this warming uniform throughout the entire depth? I don't believe so, I think various ocean layers are practically on different planets. But I don't think it makes a difference, less warming at lower levels just means more warming at higher levels, producing the same effect. > Is this warming uniform throughout the entire depth? I don't think so, this is where waters uncompressability comes into play.
- yongjik 9y ago
  Yes, actually it is a significant factor. https://en.wikipedia.org/wiki/Sea_level_rise https://en.wikipedia.org/wiki/Sea_level_rise > Based on figures from between 1993–2008 two thirds (68%) of recent sea level rise has been attributed by melting ice, and roughly one third has come from thermal expansion. https://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-5-1.html https://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-5-1... > During recent years (1993–2003), for which the observing system is much better, thermal expansion and melting of land ice each account for about half of the observed sea level rise, although there is some uncertainty in the estimates.
dwaltrip 9y ago
The bigger deal is that ice is very reflective. Reflected light energy promotes cooler temperatures. Water is far less reflective, and so it absorbs significantly more incoming light energy, providing a general warming effect.

nimchimpsky 9y ago

Eh ? Sea level rises are due to land based ice melting.

discoursism 9y ago

Edit: this paragraph is full of lies. -- There are a lot of things to be worried about with global warming, but I have never heard the density of ocean water listed among them. Water at 24 C is 0.002 less dense than water at 14 C. Since 10 C swings in global temperatures would long have caused catastrophes in other domains, I don't think we'll be much bothered by this small of a change in ocean density. Please enlighten me if I am incorrect. Edit: thanks, all. I stand corrected.

teraflop 9y ago
A 0.002 relative change in density is actually quite a lot, if you consider that the oceans are 12,000 feet deep on average.
flukus 9y ago
If I'm correct (not a hydrologist) 0.002 decrease in density translates to a 2M (~6 feet) sea level rise per KM of ocean. Some quick googling suggest that the average ocean depth is close to 4KM. So even small changes can have noticeable effect, particular when it's combined with other changes.
- yters 9y ago
  I'd be interested to hear more on this. Is this warming uniform throughout the entire depth? Does the change in density impact the ocean uniformly or mostly on the top layer where the pressure is less?
  - flukus 9y ago
    Take everything with a huge grain of salt here, I'm far from an authority on any of this, some of it I don't really grasp myself. > Is this warming uniform throughout the entire depth? I don't believe so, I think various ocean layers are practically on different planets. But I don't think it makes a difference, less warming at lower levels just means more warming at higher levels, producing the same effect. > Is this warming uniform throughout the entire depth? I don't think so, this is where waters uncompressability comes into play.
yongjik 9y ago
Yes, actually it is a significant factor. https://en.wikipedia.org/wiki/Sea_level_rise https://en.wikipedia.org/wiki/Sea_level_rise > Based on figures from between 1993–2008 two thirds (68%) of recent sea level rise has been attributed by melting ice, and roughly one third has come from thermal expansion. https://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-5-1.html https://www.ipcc.ch/publications_and_data/ar4/wg1/en/faq-5-1... > During recent years (1993–2003), for which the observing system is much better, thermal expansion and melting of land ice each account for about half of the observed sea level rise, although there is some uncertainty in the estimates.

dwaltrip 9y ago

The bigger deal is that ice is very reflective. Reflected light energy promotes cooler temperatures. Water is far less reflective, and so it absorbs significantly more incoming light energy, providing a general warming effect.