16 myo, the Columbia River Basalt Floods released enough CO2 to raise sea level 40 meters

[repoman]

Pretty interesting article and applicable to our near future:

https://www.skepticalscience.com/print.php?n=2845

 

[Underseer]

Please forgive me for not reading the whole thing, and I know that this blog is generally considered good and properly cites primary sources, but forty meters over what time period? The current sea level rise is measured in millimeters per year.

 

[Loren Pechtel]

Please forgive me for not reading the whole thing, and I know that this blog is generally considered good and properly cites primary sources, but forty meters over what time period? The current sea level rise is measured in millimeters per year.

I doubt they know.

 

[bilby]

Please forgive me for not reading the whole thing, and I know that this blog is generally considered good and properly cites primary sources, but forty meters over what time period? The current sea level rise is measured in millimeters per year.

I doubt they know.

The article gives a range of between 10,000 and 300,000 years for the carbon dioxide releases; presumably the sea level change would have occurred over a similar period.

 

[repoman]

I think that sea level over time is probably moderately well known by the experts. It is a matter of laymen finding that info that is difficult.

I am just saying that our descendants are in for the very long haul for sea level rise.

 

[Loren Pechtel]

I doubt they know.

The article gives a range of between 10,000 and 300,000 years for the carbon dioxide releases; presumably the sea level change would have occurred over a similar period.

I think that sea level over time is probably moderately well known by the experts. It is a matter of laymen finding that info that is difficult.

I am just saying that our descendants are in for the very long haul for sea level rise.

"Moderately well known" isn't going to give data of useful accuracy given how far in the past we are talking about. Even a 1% error is over 100k years--utterly useless in trying to predict what is going to happen to Earth now.

 

[fromderinside]

The article gives a range of between 10,000 and 300,000 years for the carbon dioxide releases; presumably the sea level change would have occurred over a similar period.

I think that sea level over time is probably moderately well known by the experts. It is a matter of laymen finding that info that is difficult.

I am just saying that our descendants are in for the very long haul for sea level rise.

"Moderately well known" isn't going to give data of useful accuracy given how far in the past we are talking about. Even a 1% error is over 100k years--utterly useless in trying to predict what is going to happen to Earth now.

Seems to me that if the Glacier park super volcano was erupting about every 600 k years (https://en.wikipedia.org/wiki/Yellowstone_Caldera#/media/File:Yellowstone_Caldera_map2.JPG), that it may have interfered or accelerated the to-be Columbia river basalt events https://en.wikipedia.org/wiki/Columbia_River_Basalt_Group#Dating_of_the_flood_basalt_flows. Seems apparent enough to me that the ocean rose and fell significant amounts in the last 1.5 million years. I believe it had to be about 450 feet lower to permit aborigines to migrate to Australia, for instance, around 40-55 thousand years ago http://www.migrationheritage.nsw.gov.au/cms/wp-content/uploads/2008/06/Map-of-ice-age-Aust.jpg Again there was probably enough of a decline in ocean depth around 13-15 thousand years ago to permit migration to America from Asia. Then there were to multiple collapses of glacial dams in the last one and one half million years to create the lake Missuola floods http://www.glaciallakemissoula.org/virtualtour/

 

[Loren Pechtel]

I think that sea level over time is probably moderately well known by the experts. It is a matter of laymen finding that info that is difficult.

I am just saying that our descendants are in for the very long haul for sea level rise.

"Moderately well known" isn't going to give data of useful accuracy given how far in the past we are talking about. Even a 1% error is over 100k years--utterly useless in trying to predict what is going to happen to Earth now.

Seems to me that if the Glacier park super volcano was erupting about every 600 k years (https://en.wikipedia.org/wiki/Yellowstone_Caldera#/media/File:Yellowstone_Caldera_map2.JPG), that it may have interfered or accelerated the to-be Columbia river basalt events https://en.wikipedia.org/wiki/Columbia_River_Basalt_Group#Dating_of_the_flood_basalt_flows. Seems apparent enough to me that the ocean rose and fell significant amounts in the last 1.5 million years. I believe it had to be about 450 feet lower to permit aborigines to migrate to Australia, for instance, around 40-55 thousand years ago http://www.migrationheritage.nsw.gov.au/cms/wp-content/uploads/2008/06/Map-of-ice-age-Aust.jpg Again there was probably enough of a decline in ocean depth around 13-15 thousand years ago to permit migration to America from Asia. Then there were to multiple collapses of glacial dams in the last one and one half million years to create the lake Missuola floods http://www.glaciallakemissoula.org/virtualtour/

Yeah, we can conclude that climate change can have a substantial impact on sea level. What we can't see from the historical data is how fast it can move.

 

[bilby]

I think that sea level over time is probably moderately well known by the experts. It is a matter of laymen finding that info that is difficult.

I am just saying that our descendants are in for the very long haul for sea level rise.

"Moderately well known" isn't going to give data of useful accuracy given how far in the past we are talking about. Even a 1% error is over 100k years--utterly useless in trying to predict what is going to happen to Earth now.

Seems to me that if the Glacier park super volcano was erupting about every 600 k years (https://en.wikipedia.org/wiki/Yellowstone_Caldera#/media/File:Yellowstone_Caldera_map2.JPG), that it may have interfered or accelerated the to-be Columbia river basalt events https://en.wikipedia.org/wiki/Columbia_River_Basalt_Group#Dating_of_the_flood_basalt_flows. Seems apparent enough to me that the ocean rose and fell significant amounts in the last 1.5 million years. I believe it had to be about 450 feet lower to permit aborigines to migrate to Australia, for instance, around 40-55 thousand years ago http://www.migrationheritage.nsw.gov.au/cms/wp-content/uploads/2008/06/Map-of-ice-age-Aust.jpg Again there was probably enough of a decline in ocean depth around 13-15 thousand years ago to permit migration to America from Asia. Then there were to multiple collapses of glacial dams in the last one and one half million years to create the lake Missuola floods http://www.glaciallakemissoula.org/virtualtour/

Yeah, we can conclude that climate change can have a substantial impact on sea level. What we can't see from the historical data is how fast it can move.

We can set an upper bound fairly easily though, by calculating the additional energy due to radiative forcing, and plugging in the heat of fusion of ice.

The Antarctic icecap contains 2.65x10¹⁹kg of ice, which Google tells me is enough to raise sea level by 58m if it all melted.

To melt that much ice requires 8.8x10²⁴J of heat; The IPCC estimates that in 2014, the additional radiative forcing due to Greenhouse Gasses (compared to the pre-industrial baseline year of 1750) is 2.936Wm^-2. Plugging in the surface area of the Earth, 5x10¹⁴m², we get an additional insolation due to GHG of 1.5x10¹⁵W, which would take 6x10⁹s to melt that ice, assuming that all of the additional energy went into the Antarctic icecap, and the rest of the world remained at its current temperature.

That gives a fastest possible melt time of ~190 years, and sea level rise at a rate of about 2.25 years per metre.

Of course, the actual time required must be far larger than this, as the heat will not only go into the Antarctic ice cap - a significant fraction will go to melting Arctic ice (which has no effect on sea level as it is already floating), and to warming the oceans (which will increase sea levels slightly due to thermal expansion), the atmosphere, and the Earth's crust. However it is also worth noting that the 2014 value of 481ppmCO₂eq of GHGs has already been exceeded, and likely will continue to rise over the next two centuries, so that will tend to accelerate the rate of ice loss.

I would hazard a guess that we can expect to see, at the absolute worst, about one third of the extra heat going to the Antarctic ice (with a third going to Arctic ice, and another third into the oceans and crust), giving a worst case scenario of ~7 years per metre of sea level rise; So we can guesstimate that 40m of sea level rise will take a minimum of 270 years to occur. That's effectively instantaneous in geological terms, and at 150mm (6 inches, for those watching in black and white) per year, is FAR faster than the current rate of sea level increase, which is about 3mm (0.1 inches) per year.

Of course, this is a VERY crude 'worst case' guesstimate; The real rate could be dramatically slower (if the proportion of the energy that goes to melting Antarctic ice is significantly less than a third of the additional amount due to radiative forcing, which my gut tells me it likely is). But Back-of-the-Napkin-Physics suggests it is not likely to be significantly faster.

Of course, sea level is not the only concern. Ocean acidification will be another major issue, as will increases in severe weather events, and changes in rainfall patterns worldwide. All of these will have major impacts on humans, even if sea level rise were to turn out to be far slower than this guesstimate suggests.

 

[Underseer]

I think that sea level over time is probably moderately well known by the experts. It is a matter of laymen finding that info that is difficult.

I am just saying that our descendants are in for the very long haul for sea level rise.

The more immediate problem is changes in precipitation patterns. Most of our current farmland was selected based on precipitation patterns that may no longer be valid, which means that as the climate changes, more and more farmland is going to fail to produce adequate amounts of food.

Furthermore, the longer we wait to fix things, the more expensive it will be to fix. I would say either of those things are more immediate issues than millimeters per year of sea level rise.

 

[bilby]

I think that sea level over time is probably moderately well known by the experts. It is a matter of laymen finding that info that is difficult.

I am just saying that our descendants are in for the very long haul for sea level rise.

"Moderately well known" isn't going to give data of useful accuracy given how far in the past we are talking about. Even a 1% error is over 100k years--utterly useless in trying to predict what is going to happen to Earth now.

Seems to me that if the Glacier park super volcano was erupting about every 600 k years (https://en.wikipedia.org/wiki/Yellowstone_Caldera#/media/File:Yellowstone_Caldera_map2.JPG), that it may have interfered or accelerated the to-be Columbia river basalt events https://en.wikipedia.org/wiki/Columbia_River_Basalt_Group#Dating_of_the_flood_basalt_flows. Seems apparent enough to me that the ocean rose and fell significant amounts in the last 1.5 million years. I believe it had to be about 450 feet lower to permit aborigines to migrate to Australia, for instance, around 40-55 thousand years ago http://www.migrationheritage.nsw.gov.au/cms/wp-content/uploads/2008/06/Map-of-ice-age-Aust.jpg Again there was probably enough of a decline in ocean depth around 13-15 thousand years ago to permit migration to America from Asia. Then there were to multiple collapses of glacial dams in the last one and one half million years to create the lake Missuola floods http://www.glaciallakemissoula.org/virtualtour/

Yeah, we can conclude that climate change can have a substantial impact on sea level. What we can't see from the historical data is how fast it can move.

We can set an upper bound fairly easily though, by calculating the additional energy due to radiative forcing, and plugging in the heat of fusion of ice.

The Antarctic icecap contains 2.65x10¹⁹kg of ice, which Google tells me is enough to raise sea level by 58m if it all melted.

To melt that much ice requires 8.8x10²⁴J of heat; The IPCC estimates that in 2014, the additional radiative forcing due to Greenhouse Gasses (compared to the pre-industrial baseline year of 1750) is 2.936Wm^-2. Plugging in the surface area of the Earth, 5x10¹⁴m², we get an additional insolation due to GHG of 1.5x10¹⁵W, which would take 6x10⁹s to melt that ice, assuming that all of the additional energy went into the Antarctic icecap, and the rest of the world remained at its current temperature.

That gives a fastest possible melt time of ~190 years, and sea level rise at a rate of about 2.25 years per metre.

Of course, the actual time required must be far larger than this, as the heat will not only go into the Antarctic ice cap - a significant fraction will go to melting Arctic ice (which has no effect on sea level as it is already floating), and to warming the oceans (which will increase sea levels slightly due to thermal expansion), the atmosphere, and the Earth's crust. However it is also worth noting that the 2014 value of 481ppmCO₂eq of GHGs has already been exceeded, and likely will continue to rise over the next two centuries, so that will tend to accelerate the rate of ice loss.

I would hazard a guess that we can expect to see, at the absolute worst, about one third of the extra heat going to the Antarctic ice (with a third going to Arctic ice, and another third into the oceans and crust), giving a worst case scenario of ~7 years per metre of sea level rise; So we can guesstimate that 40m of sea level rise will take a minimum of 270 years to occur. That's effectively instantaneous in geological terms, and at 150mm (6 inches, for those watching in black and white) per year, is FAR faster than the current rate of sea level increase, which is about 3mm (0.1 inches) per year.

Of course, this is a VERY crude 'worst case' guesstimate; The real rate could be dramatically slower (if the proportion of the energy that goes to melting Antarctic ice is significantly less than a third of the additional amount due to radiative forcing, which my gut tells me it likely is). But Back-of-the-Napkin-Physics suggests it is not likely to be significantly faster.

Of course, sea level is not the only concern. Ocean acidification will be another major issue, as will increases in severe weather events, and changes in rainfall patterns worldwide. All of these will have major impacts on humans, even if sea level rise were to turn out to be far slower than this guesstimate suggests.

On reflection, it occurs to me that there is a mechanism by which sea level rise could be much faster.

If higher global temperatures allowed the Antarctic and/or Greenland land ice to slide off the land and into the ocean, then it wouldn't be necessary for the ice to melt - as soon as it is floating, it will displace enough water to have the same effect on sea level as if it had melted.

So if warmer climate leads to faster glacial flows into the ocean, sea level rise could be markedly more rapid than my earlier figures imply.

There is some evidence that the floating ice shelves around Antarctica are breaking up, which could lead to more rapid glacial ice flow into the ocean in the areas currently occupied by that sea ice.

Of course, glaciers are notoriously (indeed eponymously) glacial in their flow; a fast glacier is not in the same league as a slow river in terms of bringing water into the sea. But they could certainly bring ice off the land far faster than it could melt.

 

[Loren Pechtel]

On reflection, it occurs to me that there is a mechanism by which sea level rise could be much faster.

If higher global temperatures allowed the Antarctic and/or Greenland land ice to slide off the land and into the ocean, then it wouldn't be necessary for the ice to melt - as soon as it is floating, it will displace enough water to have the same effect on sea level as if it had melted.

So if warmer climate leads to faster glacial flows into the ocean, sea level rise could be markedly more rapid than my earlier figures imply.

There is some evidence that the floating ice shelves around Antarctica are breaking up, which could lead to more rapid glacial ice flow into the ocean in the areas currently occupied by that sea ice.

Of course, glaciers are notoriously (indeed eponymously) glacial in their flow; a fast glacier is not in the same league as a slow river in terms of bringing water into the sea. But they could certainly bring ice off the land far faster than it could melt.

Not only that, but if it falls into the ocean the ocean water can melt it by cooling, no additional solar heat needed.

As I said before, this data is useless for showing how fast it can happen.

 

[bilby]

On reflection, it occurs to me that there is a mechanism by which sea level rise could be much faster.

If higher global temperatures allowed the Antarctic and/or Greenland land ice to slide off the land and into the ocean, then it wouldn't be necessary for the ice to melt - as soon as it is floating, it will displace enough water to have the same effect on sea level as if it had melted.

So if warmer climate leads to faster glacial flows into the ocean, sea level rise could be markedly more rapid than my earlier figures imply.

There is some evidence that the floating ice shelves around Antarctica are breaking up, which could lead to more rapid glacial ice flow into the ocean in the areas currently occupied by that sea ice.

Of course, glaciers are notoriously (indeed eponymously) glacial in their flow; a fast glacier is not in the same league as a slow river in terms of bringing water into the sea. But they could certainly bring ice off the land far faster than it could melt.

Not only that, but if it falls into the ocean the ocean water can melt it by cooling, no additional solar heat needed.

As I said before, this data is useless for showing how fast it can happen.

Once it's in the ocean, it doesn't matter how fast it melts (or even whether it melts at all).