Sea level rise due to global warming

Factual Questions
1

Hello Everyone,

Full disclaimer, I am not convinced that any global temperature change is man made. However, I have tried to keep an open mind and read some about it before setting my opinion in concrete. I am not wanting my question to morph into an argument wether GW is real or not.

The question I have is that many on who claim GW is man made and real keep saying that the icebergs in the polar regions are melting and this will eventually result in a catastrophic rise in the sea level. This is one claim I can’t seem to wrap my head around. If the icebergs are already in the water, then they are already displacing their weight and melting wouldn’t add anything to the sea level. Just wondering if that would be correct.

However, just thinking about it, perhaps they weren’t so much referring to the icebergs as much as the ice covering land masses. E en so, is there really enough ice that could make much difference in sea level. I know there is a lot of ice, but the oceans are huge. Perhaps I can’t imagine there is enough ice to impact sea level in a meaningful way.

Anyway, just thinking.

2

The two factors cited in sea-level rise are expansion (water expands as it warms) and land-ice melting (glaciers in particular).

From an IPCC report:

http://www.ipcc.ch/publications_and_data/ar4/wg2/en/spmsspm-c-15-magnitudes-of.html

ETA: Ice sheet melting is a much longer-term process than glaciers. Hundreds to thousands of years vs. decades.

3

Yes, they are refrring to ice on land, especially the Antarctic land mass, which is huge, and elevated above the water. Greenland also is expected to add to this, along with glacial ice from various places. see here:

In fact, the rise isn’t equal everywhere. The US Geological Survey reported just last week that the rise along the East Coast ogf the US is accelerating several times the average value:

4

What is clear is that most climate change researchers do see a rise of a foot or more by the end of the century, but that is based on the conservative estimates that they themselves acknowledge that do not include a possible acceleration of the melting, the recent data shows that the melting is accelerating, mostly in the poles, so more than just a few feet can come, the main problem is that the end of the century is not the end of time, with no control of our emissions of global warming gases, then eventually in a few centuries the oceans can rise up to 200 feet.

5

Not wanting to start any arguments, but why is this? Virtually all natural cycles (e.g. solar activity) say that the Earth should have been cooling for the past few decades; sure, some people (mostly non-scientists, or rather, non-climate scientists, which excludes meteorologists and the like) make claims that this or that is causing global warming but their arguments aren’t supported by the evidence.

And yes, like the others have said, it is land ice, not sea ice that is the concern, although as Arctic sea ice melts it will reinforce warming in the region, which has a major ice sheet (Greenland) which is already experiencing accelerating melt (and could have another record melt season this year, same goes for the sea ice - the U.S. isn’t the only place that has been unusually warm lately, see the global analysis for May).

6

Natural global warming since the last ice age has already raised the sea level by 300 feet. If all the remaining continental ice on Greenland and Antarctica melts, we’re looking at another 200 feet (as GIGObuster already noted). There is most definitely enough ice there.

7

Mainly because as a kid growing up in the 80’s I can clearly remember the theme then was Global Cooling and we were on the verge of another ice age. Seems as with coffee good for you then bad for you, scientist can’t seem to nail these things down. What was touted as fact this decade is written of as wrong the next. I don’t doubt that temporaries are rising, but am not convinced at this point it is entirely man made and not just a natural fluctuation. Once again, not saying I don’t believe it is happening, just that I haven’t been convinced of it yet.

8

BTW, you’d be better off not using weather arguments, since some areas (for example, the Pacific Northwest) have been unusually cool this summer. That just gives people ammo. You need to make it clear that it’s the average temperature over decades that matters, not year-to-year weather patterns.

9

Who says that? Because you are exactly right, sea-ice melting makes no different to sealevel. Salinity, yes, but not sealevel.

So can you point us to some of these “many”?

10

I’m not sure anyone does make it the crux of their argument, but it does lessen the reflectivity of the earth since ice reflects better than open water and thus is a positive feedback loop in global warming. But I don’t know how big that effect is.

11

Is this right? Anyone who has put a water bottle in their freezer can tell you that water expands as it freezes. If it also expands when it melts, then after a few hundred freeze-thaw cycles we’ll have a solid ice planet the size of Jupiter.

12

Water is “smallest” at 4ºC. it expands as it freezes due to the crystal structure, which is actually rather an unusual property.

13

You have to separate the difference between science and science news. The two items have, effectively, no correspondence to one another. Interesting and fascinating ideas by whacko one-off scientists get a lot of news coverage, regardless of whether there’s been any peer review of the research, let alone peer acceptance.

If you look back, you won’t find large government agencies dedicated to the study of Global Cooling, in the 80s. If you look at modern day, every modern nation’s government has at least one group studying Global Warming. If you look at the guys who Ronald Reagan/George Bush I appointed to the head of the EPA, they’re going around doing their best to convince people that global warming is real.

14

I say many because I have heard this claim “many” times. A Google search on rising sea level due to GW brings over twenty million hits, which I would say qualifies as many. However, I didn’t imply that ALL supporters of the GW theory claim there will be a rise in sea level. Which is why I choose the term many, as in more than a few.

15

Are these many hits saying that sea levels will rise due to melting icebergs or melting icecaps? (And the expansion of warmer water.)

16

Well, at first I assumed they were discussing icebergs, but then as demonstrated in the second paragraph of my OP I reasoned that they must have meant the ice caps. Hence what evolved into a two part question. The first about the icebergs, the second asking if there was enough water in the ice caps to noticeably affect the sea level. Plus just out of curiosity I wanted to confirm my thought that even if the icebergs melted the sea level wouldn’t change because of displacement. Simple really. :smiley:

17

Unfortunately, that was a case of the media misreporting things (if not outright lying); you still see the same thing today (Google “coming ice age” or such and you’ll see what I mean;; the first result for that phrase is a website called iceagenow which claims that another ice age is imminent if not already beginning, next is “scientists predict coming ice age”, dated this year). Yes, those stories in the 70s were based on a grain of truth, but no, scientists weren’t claiming that another ice age (or cooling) was imminent. Among other things, it was based on concerns that aerosols might offset greenhouse gasses (we now know that they have masked about half the warming that would have occurred otherwise). Nowadays you usually see stories about how the Sun is going into another Maunder Minimum or some such (or just from the current solar cycle, likely to be the weakest in a century, but note that the strongest solar cycles were in the 1950s), which won’t have much of an effect unless solar irradiance somehow fell much lower than it did back then, currently we would make up for it in just 7 years of CO2 increase (scroll down to graph of TSI).

18

I an fairly certain that you misheard or misremembered this claim, then. No-one with any knowledge of the matter (or indeed of science in general) would make such a patently silly claim; if you yourself worked out floating ice cannot affect sealevel by melting then you could hardly believe that any scientist could make such an error.

If you can find specific references to any qualified scientist asserting this I’ll be very surprised.

19

As has been pointed out already, you’ve either misread or the people who said this misread themselves. The worry is about ice on land (Northern Canada, Greenland, Siberia, etc.) melting and running into the ocean. Ice which is already floating in the ocean won’t affect the overall depth of the ocean as it melts.

The last IPCC report that I looked through also predicted no more than a maximum of 2-3 feet of gain in depth over the next century or two. While this is problematic to people who live very near to the beach and the Netherlands – the whole nation is at or under sea level already – it’s not a catastrophe in itself.

Where there would be a greater worry is that larger, warmer oceans will have a greater effect on weather. Hurricanes are, effectively, powered by the ocean. If the ocean has more power to give, then you get stronger hurricanes. With an overall faster wind speed across the globe, this will generally make cooler climates colder and warmer climates even hotter (temperate climates will shift towards warmer.) This plays havoc with ecology. In the US, changing out what plants are grown in what regions isn’t too difficult, but in the majority of the impoverished world, a shift in what plants are sustainable is hard to maintain.

Overall, of effects that we expect from data, in the US and Europe, the main issue is going to be the cost of adaptation. Houses which have been hardened to modern day hurricanes will become insufficient. Prime farming territory will move out of the US West Coast and into the Canadian West Coast. Some number of lives will be lost to historically unparalleled storms during the period of change. But, like Katrina, the vast majority of the population will be fine, and it will mostly be the poor and sickly who come to harm. Seeing as you’ve enough free time to argue politics on the internet, you’re probably not among these.

Catastrophe will mostly hit Africa and poor nations around the world – but not necessarily more than is already caused by simple tyranny and poor governance. Installing a better government and teaching modern economics to the general populace could likely do better for most of these areas than stopping global warming.

BUT, there is always the chance that significant, reallocated weight on the tidal plates will cause massive earthquakes and massive tsunamis – which are a lot less predictable and a lot harder to build for. There’s also the possibility that the raised temperature will cross some lynchpin boundary which could then cause a mass extinction event.

It’s also worth noting that most of the suggested changes for our nation to make, like transitioning to more fuel efficient vehicles, less power hungry light bulbs, a smarter power grid, and nuclear energy, are all more efficient and subsequently (in the long run) cheaper than what we have today (as well as reducing the amount of money that we pump into 3rd world nations). Even if climate change wasn’t happening or wasn’t caused by man, there wouldn’t be much value in arguing against the recommendations of the carbon-cutting crowd.