sea level rise

[Handy andy]

Could an ice comet 12000 years ago have initiated the younger dryas period and sea level rise globally? could it happen again?. A ice comet approx. 30km diameter could raise sea levels globally 20m, and could have initiated a global extinction event, and global climate change.

 

A comet would not need to have a direct hit on earth it could be captured in the earths gravitational field and orbit the planet slowly breaking up before coming to earth.

 

A link from the scientific American magazine

 

https://www.scientificamerican.com/article/did-a-comet-hit-earth-12900-years-ago/

 

Nasa on sea levels

 

https://www.giss.nasa.gov/research/briefs/gornitz_09/

 

One of many near miss links

 

https://www.usatoday.com/story/news/nation/2014/10/16/mars-comet-near-miss-planet-collide/17370459/

 

 

[swansont]

A comet would not need to have a direct hit on earth it could be captured in the earths gravitational field and orbit the planet slowly breaking up before coming to earth.

 

How would that happen?

[Handy andy]

How would that happen?

 

Shit happens

 

Comet Shoemaker Levy was captured in the orbit of Jupiter circa 1992 it took an estimated 2 years to break up. Finally impacting with the planet in 1994, it was first observed in 1993 orbiting the planet.

 

https://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9

 

Was all the water on the planet in place when the planet was formed or could there have been a more recent addition 12000 years ago causing sea level rise.

 

There is no reason why a comet could not hit the planet, the moon shows multiple impacts and it is just next door, we have had many near misses, and there is no reason it couldn't happen again.

 

There are lots of huge lumps of ice in the Keppler belt, some of which are orbiting the opposite direction to the other blocks of ice, these could collide causing them to change their orbit and hit the earth, that is if Jupiter does not get in the way.

 

The planet has been hit in the past, could a comet breaking up in the earths atmosphere cause sea level rise, on a biblical scale

[DrP]

I think the initial impact would give us more to worry about than a sea level rise. If it was that big then it would be a catastrophic event anyway. I am not sure any one would be left to witness the ensuing sea level rise.

[Handy andy]

I think the initial impact would give us more to worry about than a sea level rise. If it was that big then it would be a catastrophic event anyway. I am not sure any one would be left to witness the ensuing sea level rise.

 

Assuming we survived the initial impact or multiple impacts, and were not wiped out in some mini glacial period such as the younger dryas period, could this explain sea level rise approx 12000 years ago.

 

The climate change models which predicted massive sea level rise when the ice caps were all melted seem to have over estimated the effect of global warming and sea level rise.

 

Global warming of the oceans provides more energy for stronger storms, and coastal storm surges during bad weather, but the mean sea level does not seem to be changing noticeably.

 

I am just wondering if the many sea level rises over the history of the earth have another explanation.

[swansont]

Shit happens

 

Comet Shoemaker Levy was captured in the orbit of Jupiter circa 1992 it took an estimated 2 years to break up. Finally impacting with the planet in 1994, it was first observed in 1993 orbiting the planet.

 

Jupiter has a mass >300x of earth.

 

"Shit happens" doesn't cut it for defending conjecture.

 

Keppler belt? Did you mean Kuiper belt?

[MigL]

!5000 yrs ago the glaciers over North America went as far South as the Ohio valley.

By 12000 yrs ago they were quickly retreating North, carving out the Great Lakes system..

Could that have contributed to the rise in sea levels ?

 

Melting floating ice does not contribute to sea level rise.

Melting ice over land does.

So while melting the ice cover of Antarctica would raise sea levels considerably, melting The Arctic ice would not.

[Handy andy]

Jupiter has a mass >300x of earth.

 

"Shit happens" doesn't cut it for defending conjecture.

 

Keppler belt? Did you mean Kuiper belt?

 

Sorry again I know "shit happens" is not a defence, but it is the first answer that sprang in to my head and I thought it was amusing not annoying .

 

Yes I meant Kuiper belt which was studied by the Kepler mission. http://www.astronomy.ohio-state.edu/~gaudi/kvk.pdf

!5000 yrs ago the glaciers over North America went as far South as the Ohio valley.

By 12000 yrs ago they were quickly retreating North, carving out the Great Lakes system..

Could that have contributed to the rise in sea levels ?

 

Melting floating ice does not contribute to sea level rise.

Melting ice over land does.

So while melting the ice cover of Antarctica would raise sea levels considerably, melting The Arctic ice would not.

 

So do you still think climate change models are still accurate ref sea level rise and we can expect many low lying islands and coastal cities such as London and Washington DC to go under water, along with Bangladesh and other highly populated land masses.

 

Would you further state that worrying about star wars and asteroid or comet impacts diminishes into insignificance against the human disaster that is possibly predictably approaching that some politicians and world leaders don't seem to be to concerned about.

 

I don't think spending a few dollars more will do much to avoid the problem if it is going to happen. But carrying on driving around in huge petrol guzzling pink cadillacs isn't going to help either.

 

I guess !5000 is 15000

Edited May 31, 2017 by Handy andy

[swansont]

 

Sorry again I know "shit happens" is not a defence, but it is the first answer that sprang in to my head and I thought it was amusing not annoying .

 

 

 

But apparently no second answer sprung into your head.

[EdEarl]

An ice comet 30km dia is a few orders of magnitude too small to cause a 20m rise in the oceans from water stored in the comet. The kinetic energy of that size comet might melt enough glaciers and ice packs to raise the sea significantly, but it's a complex problem. I think simulations could improve most on your guess.

[Sensei]

A ice comet approx. 30km diameter could raise sea levels globally 20m

Let's assume comet is sphere, and that density of water is equal to ice, for simplification.

 

Volume of sphere is:

[math]V = \frac{4}{3} \pi r^3[/math]

 

r=15km = 15000m

[math]V = \frac{4}{3} \pi 15000^3 = 1.414 * 10^{13} m^3[/math]

 

Divide by area of Earth:

r=6370 km = 6370000m

[math]A = 4 \pi r^2[/math]

5.1*10^14 m^2

 

[math]1.414 * 10^{13} m^3 / 5.1*10^{14} m^2 = 0.028 m = 28 cm[/math]

 

30 km large ice comet would rise sea level only 28 cm.

[Handy andy]

 

 

But apparently no second answer sprung into your head.

 

You are so wrong Many answers have sprung into my head. The most interesting one, is more to do with the amount of ice that would have to arrive in the oceans to facilitate a significant sea level rise. A 30km diameter block of ice might be too small giving approx 14 139km^3 of water. How about a piece of ice the size of Antarctica with an area 14 000 000 km^2 and depth of approx. 1.9km. This would give approx. 28 000 000 km^3 of additional water in the oceans.

 

Total surface area of earth: 510,072,000 sq km Total water surface area: 70.8% (361,132,000 sq km) Total land surface area: 29.2% (148,940,000 sq km).

 

Very approximately if all the ice in Antarctica was to melt and spread evenly over the earths surface, the global sea level would rise 14/510 *1900 m of additional water depth globally = 52m . I hope I have put a decimal place in the wrong place, if I haven't don't panic because politicians don't think it is a problem and we are all safe, because climatologists are wrong and global warming isn't going to happen.

 

How much would the earths temperature have to rise to melt Antarctica and how long would it take?

Let's assume comet is sphere, and that density of water is equal to ice, for simplification.

 

Volume of sphere is:

[math]V = \frac{4}{3} \pi r^3[/math]

 

r=15km = 15000m

[math]V = \frac{4}{3} \pi 15000^3 = 1.414 * 10^{13} m^3[/math]

 

Divide by area of Earth:

r=6370 km = 6370000m

[math]A = 4 \pi r^2[/math]

5.1*10^14 m^2

 

[math]1.414 * 10^{13} m^3 / 5.1*10^{14} m^2 = 0.028 m = 28 cm[/math]

 

30 km large ice comet would rise sea level only 28 cm.

 

Thanks for the sums, There are places in the world where 28cm more than a 1/4m can make a huge difference. The San Blas Islands in the Carribean for instance, Venice, Amsterdam, Bangladesh, too many places to mention.

[Janus]

Shit happens

 

Comet Shoemaker Levy was captured in the orbit of Jupiter circa 1992 it took an estimated 2 years to break up. Finally impacting with the planet in 1994, it was first observed in 1993 orbiting the planet.

 

https://en.wikipedia.org/wiki/Comet_Shoemaker–Levy_9

No. Shoemaker Levy was estimated to have been captured by Jupiter in either the '60s or 70's, and orbited Jupiter for several decades before '92, when its orbit took it within Jupiter's Roche limit at perijove(likely caused by interaction with one of Jupiter's moons), which precipitated its break up.

 

Prior to its capture, it was likely had an orbit with an aphelion near Jupiter's orbit and a perihelion in the outer part of the asteroid belt. This would result in it having a low relative velocity with respect to Jupiter which is what allowed for Jupiter to capture it.

 

For Earth to capture such a comet, the relative velocity difference would have to be even smaller, due to Earth's mass. This is made more difficult by the fact that orbital speeds themselves are greater at the Earth's distance from the Sun than they are at Jupiter's. This in turn would require the comet's orbit to be much more similar to Earth's to allow a capture. Comets can't last long orbiting that close to the Sun. So the truth of the matter is that there are no comets in the type of orbit they would need to be in to be able to be captured into orbit around the Earth.

[swansont]

Let's assume comet is sphere, and that density of water is equal to ice, for simplification.Volume of sphere is:[math]V = \frac{4}{3} \pi r^3[/math] r=15km = 15000m[math]V = \frac{4}{3} \pi 15000^3 = 1.414 * 10^{13} m^3[/math]Divide by area of Earth:r=6370 km = 6370000m[math]A = 4 \pi r^2[/math]5.1*10^14 m^2[math]1.414 * 10^{13} m^3 / 5.1*10^{14} m^2 = 0.028 m = 28 cm[/math]30 km large ice comet would rise sea level only 28 cm.

0.028m is 28mm, not 28cm

[Handy andy]

!5000 yrs ago the glaciers over North America went as far South as the Ohio valley.

By 12000 yrs ago they were quickly retreating North, carving out the Great Lakes system..

Could that have contributed to the rise in sea levels ?

 

Melting floating ice does not contribute to sea level rise.

Melting ice over land does.

So while melting the ice cover of Antarctica would raise sea levels considerably, melting The Arctic ice would not.

 

Is Antarctic gaining or losing ice. Apparently the amount of sea ice may be increasing whilst the land ice is reducing. How quickly can sea levels rise if the Antarctic ice sheet melts over land.

 

The Greenland ice sheet is also melting.

 

Is coastal property a good investment, beyond 2100, should we be looking to sell now.

 

https://www.skepticalscience.com/antarctica-gaining-ice.htm

 

Is the sea level going to rise significantly or not? 28mm might not be too serious, unless it arrived via a comet at several thousand km/hour.

 

The Antarctic and Greenland ice sheet melting is in a different league to a comet. The media pays little attention to it, should we be concerned, worried or just PANIC.

 

https://skepticalscience.com/sea-level-rise-predictions.htm

https://www.washingtonpost.com/news/energy-environment/wp/2016/03/30/antarctic-loss-could-double-expected-sea-level-rise-by-2100-scientists-say/?utm_term=.d6868ec661e4

 

It seems depending on where you look different predictions are made. Do we need to wait until sea level rises to find out which academic argument was right or wrong.

Edited May 31, 2017 by Handy andy

[Janus]

https://skepticalscience.com/sea-level-rise-predictions.htm

https://www.washingtonpost.com/news/energy-environment/wp/2016/03/30/antarctic-loss-could-double-expected-sea-level-rise-by-2100-scientists-say/?utm_term=.d6868ec661e4

 

It seems depending on where you look different predictions are made. Do we need to wait until sea level rises to find out which academic argument was right or wrong.

By using the second link's prediction of a ~15 meter rise by 2500, this is what my neck of the woods would look like:

 

[Handy andy]

Is the Larsen C ice shelf important. http://www.bbc.co.uk/news/science-environment-40113393 its breaking off.

 

I note mr trump is likely to be excelling himself this afternoon when he pulls out of the Paris accord. Cynically will this announcement help oil giants share price rise and possibly push the Dow up and improve the economy and employment in the US, at the expense of the environment.

[Handy andy]

Does any one have anything sentient to say about the United States withdrawal from the Paris Treaty, and global sea level rise or warming.

Edited June 2, 2017 by Handy andy

[DrP]

Thanks America!

[Sensei]

Does any one have anything sentient to say about the United States withdrawal from the Paris Treaty, and global sea level rise or warming.

 

Not without using many rude words...

Edited June 2, 2017 by Sensei