I actually just attended an incredibly interesting seminar about sea level rise! (ChemE grad student: the our department required it. It was way cooler than watching yet another presentation about catalysis!)
Based on what I saw, I think it's wrong to think of the ocean level as ONLY rising or ONLY sinking. Sort of like how its wrong to call global climate change "global warming": climates are complicated, and some places may end up cooler in the brave new world even if the global average is rising.
Besides the raw amount of water in the ocean, lots of other factors go into sea level rise. Some surprised me! A few interesting ones I remember:
- thermal expansion of the water: i.e. increasing the temperature of a constant amount of water causes its volume to increase
- rising or sinking land: in places like Norway or Greenland, the land is rising from all the glaciers melting. He talked about some piers he saw in Northern Europe many meters away from the seaside.
- flow of ocean currents: the ocean isn't a big bathtub, all the water is moving around. The movement causes the water to rise in some places and go down in others
- additional gravity stuff that I didn't understand.
Among many fascinating figures, he plotted where the sea level rise would be the most dramatic, and the US East Coast was one of the worst in the world. Besides the general rise in sea level affecting most of the planet, something in the ocean currents causes the water to be especially high over there.
"In the 19th century, as the Industrial Revolution took hold, the ocean began to rise briskly, climbing about eight inches since 1880."
"The sea is rising at what appears to be an accelerating pace, lately reaching a rate of about a foot per century."
"That body [The Intergovernmental Panel on Climate Change] found that continued high emissions might produce a rise in the sea of 1.7 to 3.2 feet over the 21st century."
It's all in there. Towards the bottom, so if you just skimmed you may miss it.
Yes, but what is the delta? Since we are coming out of an ice age a mere 12,000 years ago, we should expect sea level rising. The issue is how much extra sea level rise are we seeing due to anthropomorphic climate change.
I seem to remember from the first IPCC report that it was on the order of a few centimeters per century, which is why I am not greatly concerned about this. But I could be wrong.
>Since we are coming out of an ice age a mere 12,000 years ago, we should expect sea level rising.
Given that the headline is that the rate is higher than the last 2800 years, I'm not sure why you would think that the change that started 12,000 years ago is going to be a significant factor.
The IPCC summary for policymakers [1] has highlevel quick facts, from that:
>Proxy and instrumental sea level data indicate a transition in the late 19th to the early 20th century from relatively low mean rates of rise over the previous two millennia to higher rates of rise (high con dence). It is likely that the rate of global mean sea level rise has continued to increase since the early 20th century. {3.7, 5.6, 13.2}
>I seem to remember from the first IPCC report that it was on the order of a few centimeters per century
Sure, that's the currently observed rate; about 3.2 mm/year +/- 0.4 mm/year, from Table 13.1 of IPCC AR 5. [1]
Of course nobody's really concerned about 3.2 cm in a century. The problem is when that increases by a couple orders of magnitude due to increased warming, which it will unless we stop forcing the climate with additional CO2 within the next 30-50 years.
> Of course nobody's really concerned about 3.2 cm in a century.
You mean 32cm in a century at the current rate of 3.2mm/year. I think people are concerned about even that number, although the real value is likely to be significantly higher.
I know, CO2 is a greenhouse gas: So,
light from the sun warms the surface
of earth which, then, from Planck
black body radiation, radiates more
infrared light. As we can see from
our exhaled breath, CO2 is invisible,
that is, does not absorb visible light.
But CO2 does absorb light in three
narrow bands in the infrared, one band
for each of bending, twisting, and
stretching of the molecule. So, thus
absorbing infrared, CO2 gets warmer
and warms the atmosphere and is a greenhouse
gas.
I've looked a little on the Internet
for details of the absorption spectra
of CO2 and how to calculate the
rates as a function of concentration,
temperature, distance, pressure, etc.
Anyone know how to get such background
info?
That is, something like in
a greenhouse, CO2 lets the visible
light from the sun through to the
ground but traps some of the
infrared light from the ground
that otherwise would escape to space.
Maybe since the Little Ice Age,
the oceans are still warming up?
Maybe the sea level rise is due to
the water expanding due to being warmer?
Maybe the recent increases in CO2
concentration in the atmosphere
are from CO2 from the warmer oceans and
the point that cooler water absorbs more
CO2 and warmer water absorbs less and, thus,
releases CO2?
During the Little Ice Age, as civilization
grew and developed, likely the
rate of CO2 from human activity was
increasing, but, then, maybe the significantly
lower temperatures of the Little Ice Age
were due not
to less CO2 from human activity
but from less solar activity, e.g.,
in terms of sun spots,
the Maunder Minimum?
Maybe going back to the Medieval Warming Period,
the higher temperatures, IIRC, higher than now,
e.g., growing grapes in England, have
agriculture boom
and wealth and cathedral construction increase,
were due not to more CO2 from human
activity or more CO2 at all but from
more solar activity, i.e., sun spots?
Maybe the higher temperatures since the
end of the Little Ice Age have been
due to more solar activity? E.g., from
about 1940 to 1970, the CO2 from
human activity was increasing but the
level of solar activity was decreasing and,
also, the temperature was decreasing.
So, more CO2 from human activity but
lower temperatures?
Maybe the last 15 years or so of increasing
CO2 from human activity but relatively stable
temperatures have been from less solar activity?
Maybe the temperature changes are driven more
by changes in the level of solar activity than
by the changes in the levels of CO2
from human activity or the levels of CO2
in the atmosphere from CO2 released from
warmer oceans, from volcanoes, from rotting
plants, etc.?
Trying to make sense out of all of this:
Effect of solar activity? More solar
activity means more sun spots and, thus,
more solar wind blowing past earth. But,
there are claims that one of the main
sources of cloud formation on earth is
cosmic rays hitting water molecules
and, thus, stimulating the formation
of water droplets and, thus, clouds. But
supposedly more clouds have a net cooling effect,
maybe from clouds reflecting more sunlight?
So, more cosmic rays hitting the atmosphere
would have a net cooling effect.
But there are claims that more solar
wind blocks some of the cosmic rays,
thus, reduces cloud formation, and
has a net warming effect.
So, if believe this chain of causes, then
more solar activity means more sun spots,
more solar wind, fewer cosmic rays
hitting water molecules, less formation
of water droplets, less cloud formation,
and net warming. Any good sources of evidence
for such a causal chain? Anyone debunk
such stuff? Anyone believe such stuff?
Human emissions levels were very low in the Little Ice Age, compared to today. The only proto-industrialized part of the world was Europe, and Braudel estimated that Europe had access to 1.5-2.5 million horsepower total from all machinery (including wind- and water-power). That's roughly 2 gigawatts of power; we might guess that burning fuel for heat produced about the same order of magnitude. (Fuel was very expensive as late as the 1930s; Orwell has some interesting statistics in _The Road to Wiglan Pier_.) Double that is probably enough to account for the rest of the world: not more than 10 gigawatts of human-generated power and heat, some fraction of it from wind and water. 10 gigawatts is probably too large.
Today, the United States apparently consumes about 2,000 gigawatts (2 terawatts) of power from power plants, and another 2 from all other sources; Europe, China, and the rest of the world probably consume another 2-4 terawatts apiece, for close to a petawatt total -- about 100,000 times the power output of the world in the Little Ice Age.
I don't rule out the possibility that human emissions are having no effect or a limited effect -- or that their effect is positive, by keeping the Little Ice Age from developing into the real thing -- but I'm also not ruling out that the prophets of doom might be on to something. (Jeremiah was simply correct, after all.)
I'm hoping that emissions-cap negotiations get somewhere, and that we see more use of alternative energy (especially nuclear and geothermal), more artificial and biological carbon sequestration, more hybrid and electric cars (and is it too much to wish for, to hope that we see more commuter rail?), and general efforts to keep things from getting out of hand. We don't know what happens next, after all, and we only have to get it wrong once.
Besides, if these sorts of things start producing hazardous levels of global cooling in 50 years, we can just scale them back, or even remove some filters from remaining coal-fired plants. This sort of effort will be expensive, but I'd rather risk doing more than we need to than not doing enough...
Here's a related question: Supposedly
now the CO2 concentration is about
400 parts per million (maybe by weight)
and up from ballpark 200.
Okay, how much CO2 is 200 parts per million
in the atmosphere? Then, how does that
much CO2 compare with what comes from
human activity? Or, over a time interval
while CO2 concentration increases by, say,
1 part per million, how much CO2 was
generated during that time interval?
Why?
(1) The atmosphere is a biggie thing,
and maybe CO2 from human activity is
tiny in comparison, too small to represent
increasing CO2 concentration by 200 parts
per million. Need some numbers to know.
(2)There are claims that CO2 emitted into
the atmosphere by human activity is tiny
compared with that from volcanoes and
rotting vegetation. If so, then we have
to ask where the CO2 for the increased
concentration is coming from? From
the oceans as they slowly warm from
the cooling of the Little Ice Age?
My point about the cooling of the Little
Ice Age was that it was likely not caused
by reductions in CO2 from human activity.
Indeed, as the climate cooled, humans had
one heck of an incentive to burn all the
firewood they could find. So, the Little
Ice Age seems to be a case where
there was drop in temperature without
a drop in CO2 from human activity. If so,
then there have to be some causes of
temperature change other than
changes in the rate of CO2 emissions from
human activity. That is, apparently there
would be climate change even without
humans.
The title and premise of the article is that we now have news that the oceans are rising at the fastest rate over the last 2,800 years. Is the specific news event a) that the rate last year was the highest ever or b) that scientists have better calculations of the rate of rise for the last century, and these new calculations show the rise is faster than previously believed. I assumed (a), which was why I was looking in the article for what the actual rare of increase was for last year. When the article says, "lately reaching a rate of about a foot per century" is that based on recording the rise over the last century? Or is that based on multiplying last year's rise by 100?
I'm also curious -- how do we know, within plus or minus a foot -- what the sea level changes were in centuries that happened millennia ago?
1.8 to 3 millimeters a year from 25 years of satellite sea surface laser altimetry. Its not an easily obtained number because you have to account for the "noise" of much larger waves, seafloor topography gravitational distortion, multiple satellite generations, and other phenomena. But its is considered a more accurate number than local tidal gauge measurements, which is subject to local interference causes like subsidence.
I do not know if any paper has claimed an observable acceleration or deceleration of this rate yet.
Well oddly the other day NASA claimed that the climate change is also slowing down the rise that should have occurred because 3.2 trillion gallons have been soaked up by parched continents.
too be honest I am not sure who to believe and when anymore. Why do they always ratchet this stuff during US election cycles?
Still being in an interglacial time period we should expect warming, perhaps we are helping it along but cooling would likely be more devastating than warming. The odd thing about reading about glacier melt and such is that the effects are greater on your shoreline the further you are away from the affected glacier.
That linked article just leaves me in the dust at times, the connections made are just making me rethink how it all works. That we can look back at Roman actions and see that a lot of increase is recent is really cool.
(1) I work with the lead author of the study you mention (http://science.sciencemag.org/content/351/6274/699.full). It is absurd to say that the timing of his work has to do with the election cycle. He's been working on establishing the size of the groundwater component of hydrological mass balance for at least the past year. I believe the take-away from that article is that groundwater storage has to be taken into account in the next IPCC report, or else we will see missing water and we won't know why.
(2) The study you cite found that some water, that would have otherwise appeared as a sea level rise, is being sequestered as groundwater. The study in the OP said that sea level rise is higher than expected, apparently due to anthropogenic warming. These do not conflict, it's just further information about what's going on. Note also that the OP vs. the article you cite have vastly different time scales (millennia vs. decade) and consequently different precision (cm vs mm).
(3) These studies show we're learning more, because we have a lot of new observational capabilities now (like GRACE, which for the first time measures groundwater mass by its effect on Earth's gravity field). We'll continue to see new studies that establish the sizes of the dominant mass flows as we're able to learn more.
The IPCC assessment reports[1] are really well researched and comprehensive reports of the current science, including measures of confidence in plain language. They aren't hard to read, and there's any number of summaries available, including on Wikipedia[2]. It's a great place to start (and, for most non-climate-scientists, end) your research.
If you (general 'you', not you specifically, parent) want to dismiss an aggregate report of almost all climate scientists across the planet who research this stuff day in and day out as political theater, then I suggest your view of reality may be skewed by some other factor. Science provides us with data as near to facts as it's possible to get; it's up to us how to interpret those facts.
"Science provides us with data as near to facts as it's possible to get; it's up to us how to interpret those facts."
What is your definition of the word "science" in this sentence? Seems an odd use of the word. "Science" does not provide us with data. Particular people and institutions provide us with data. Furthermore when it comes to climatology, the data is hardly clear cut. All the results and predictions you read about in the paper are based on, as the article says "elaborate statistical techniques." When I hear that, my alarm bells go off. Using "elaborate statistical techniques" one can prove pretty much whatever one wants to prove.
I disagree with your use of "prove" when you wrote
Using "elaborate statistical techniques" one can prove pretty much whatever one wants to prove.
One may be able to massage data and create a nice looking chart to give an incorrect impression to unsuspecting people. This does not constitute a proof and it certainly won't pass muster with others who look at the same data and do their own statistical analyses.
I agree that my words were poorly phrased. I wanted to communicate that the IPCC report is really the best information we have, and an incredible amount of effort went into ensuring the information in the report is solid.
> one can prove pretty much whatever one wants to prove
Yes, but everyone knows this and this has been gone over again and again and everyone who studies this stuff and understands the science agrees with the report. This isn't a couple yahoos with a copy of SimEarth, this is almost every single climate scientist on the planet.
0.11 inches per year right now. We have had high precision sea level monitoring satellites up since 1992, and the measured sea level rise has been linear since then.
Actually "scientists reconstructed the level of the sea over time and confirmed that it is most likely rising faster than at any point in 28 centuries, with the rate of increase growing sharply over the past century"
'Confirmed it is most likely' is stronger than 'most likely'?
These ice cores show sudden, massive ice ages every 100,000 years. We are currently near (or overdue for) one of the big ice ages.
In such a case it would seem that a warm world, even with a higher sea level and the human movement that would require, would be less disruptive than much of current civilization being under 200 feet of ice.
That's a very convenient interpretation of the data. We are within the rounding error on a scale of several thousands of years.
If the ice age was coming RIGHT NOW, and our carbon emissions were offsetting it, and the situation could be a LOT WORSE, then MAYBE you'd have a point. (Though even in this highly unlikely scenario, you'd think we'd be able to come up with a better strategy to offset global cooling than acidifying our ocean, melting our glaciers, and inadvertently creating more extreme weather events).
But if that's NOT Happening, if that scheduled ice age is actually "due" 500 years from now, at the rate at which we are going right now, we can do a LOT of damage to our habitat, and the other living creatures on the planet before it shows up. Before the cooling comes to offset our warming we'd have created hundreds of millions of refugees from low lying watersheds, caused hundreds of species extinctions, and decreased the quality of life for every single person on the planet - not just the poor fuckers who couldn't afford new sea-walls.
Is that worth it to you? Or are you happy tasting sand with your head buried below the ground? If you are, that's great because you'll be dealing with a lot more sand in your life before it's all said and done.
About ten or fifteen years ago, I got to visit several of the Hawaiian islands. On the big island I saw new land being "created", live in front of my eyes, as lava flowed into the sea. It just kept coming.
All my life I'd thought of land as essentially permanent, only shaped by man. I realized that this was wrong - sometimes nature shifts into unstoppable mode, and the only thing we can do is to adapt - and/or get out of the way.
If there were no global warming, the next scheduled move on the Earth's climate cycle would be an ice age. I don't think that's scientifically in dispute? Besides a lot of land going under ice, and the world getting a colder, the sea levels have historically dropped around 400 feet in the mega ice ages. It would be epic.
People have survived them in the past, but it's certainly something that gets a lot of people moving.
Your capacity for self-deception is alarming. Yes, nature can be more powerful than man. But we are not powerless. The scientific consensus is not in dispute. The next asteroid to hit the earth will also be a big problem, but we need to survive until then, and the next ice age. Or, how about THRIVE, instead of survive
“The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by an endless series of hobgoblins, most of them imaginary.”
― H.L. Mencken 1922
(n.b. I'm not saying global warming is imaginary.)
That politicians love scare tactics about things real or imaginary, and even speculating things like maybe global warming is good in some circumstances (as is the parent), or that we can try things like geoengineering, etc will be quickly dismissed since it does not serve their purposes.
>In such a case it would seem that a warm world, even with a higher sea level and the human movement that would require, would be less disruptive than much of current civilization being under 200 feet of ice.
How about the fact that many human settlements are supposed to be near bodies of water (both the sea coasts and inland lakes and rivers)? At least for the former, the higher sea level could affect things a lot. Though I agree being under a lot of ice would be worse - with higher sea level at least there is the opportunity to move to higher levels of land. But there could be several factors that could still affect things or cost a huge, possibly impossible amount - one example being the amount of land used for agricultural and other use land that might be submerged. Also, people need to be reasonably near the land they work on (even if it is an office), and again, suitable replacement land for whatever use (farms, industry, offices) may not be easy to find at the higher levels that people move too.
Based on what I saw, I think it's wrong to think of the ocean level as ONLY rising or ONLY sinking. Sort of like how its wrong to call global climate change "global warming": climates are complicated, and some places may end up cooler in the brave new world even if the global average is rising.
Besides the raw amount of water in the ocean, lots of other factors go into sea level rise. Some surprised me! A few interesting ones I remember:
- thermal expansion of the water: i.e. increasing the temperature of a constant amount of water causes its volume to increase
- rising or sinking land: in places like Norway or Greenland, the land is rising from all the glaciers melting. He talked about some piers he saw in Northern Europe many meters away from the seaside.
- flow of ocean currents: the ocean isn't a big bathtub, all the water is moving around. The movement causes the water to rise in some places and go down in others
- additional gravity stuff that I didn't understand.
Among many fascinating figures, he plotted where the sea level rise would be the most dramatic, and the US East Coast was one of the worst in the world. Besides the general rise in sea level affecting most of the planet, something in the ocean currents causes the water to be especially high over there.