Small changes can cause transition to a Pliocene climate

[pietkuip]

According to a new article by Tierney et al:

Climate model simulations agree with our new analysis, suggesting that higher CO2, along with small changes in ice, vegetation, and mountains, are enough to explain Pliocene climate. We also show that the SST patterns in the Pliocene Pacific Ocean look similar to those that climate models predict under a low‐emissions climate change scenario.

[mitch]

The Tierney article said that the higher CO2 plus other feedbacks was sufficient to make a model look like the Pliocene, not that it would change the world into the Pliocene. You have to understand that the Pliocene deep ocean was about 2°C warmer than modern, a huge heat reservoir.  There will be several hundred years needed to warm the deep ocean by that extent.  If the ocean warms faster then the surface is kept more temperate.

There is inertia caused by the arrow of time--warm to cool is not the same is cool to warm.

[pietkuip]

What happens deeper down is certainly relevant for the circulation in the ocean. But the press release says:

"The reason today sea levels and ice sheets don't quite match the climate of the Pliocene is because it takes time for ice sheets to melt," Tierney said. "However, the changes in the atmosphere that happen in response to CO2 - like the changes in the trade winds and rainfall patterns - can definitely occur within the span of a human life."

[DrTskoul]

There is inertia caused by the arrow of time--warm to cool is not the same is cool to warm.

What do you mean by that ?

[Richard Rathbone]

There's a few strands to this paper.

1) The Pliocene climate wasn't what you think it was (unless you've read the paper)

2) Its actually a better analog for the climate we are heading into than was previously thought.

3) We get into that climate under low emission scenarios.

[philopek]

https://en.wikipedia.org/wiki/Pliocene

https://www.google.com/search?q=pliocene&oq=plio&aqs=chrome.0.69i59j69i57j0l3j69i60.1498j1j4&sourceid=chrome&ie=UTF-8

[DrTskoul]

The biggest differences that cannot be replicated is the atlantic / Pacific connection at the isthmus of Panama (it was not closed in most of pleiocene), the height of as several mountain ranges affecting atmospheric currents and the shape/formation of the Mediterranean...

[philopek]

The biggest differences that cannot be replicated is the atlantic / Pacific connection at the isthmus of Panama (it was not closed in most of pleiocene), the height of as several mountain ranges affecting atmospheric currents and the shape/formation of the Mediterranean...

THX, forgot about that and it's so much THE difference, whatever else.

[DrTskoul]

I didn't say they are THE differences, I just mentioned the biggest differences in the way air and ocean currents transport the heat comparing pliocene and today. For example when the isthmus of Panama closed, the oceans cooled down.

[philopek]

I didn't say they are THE differences, I just mentioned the biggest differences in the way air and ocean currents transport the heat comparing pliocene and today. For example when the isthmus of Panama closed, the oceans cooled fown.

I knew that was coming and you're right again. Was to lazy to look for a better way to emphasize.

I will remember to who i speak which is what i ask from others

[DrTskoul]

Děkuji za objasnění

[philopek]

Děkuji za objasnění

Jste vítáni, jak to, že mluvíš Česky?

Rétorická otázka, samozřejmě

Hezký večer

[DrTskoul]

Nemluvím česky.

Mr. google does though with some help.

Viděl jsem tvůj profil a myslel jsem, že odpovím zdvořile.

[pietkuip]

So that was the end of this thread I suppose

[Tor Bejnar]

But isn't the subject of this thread "Small changes can cause translation to a Praguean claim".  Without my glasses, anything is possible!

[nanning]

Don't put your glasses on Tor and we still might have a chance. 

[mitch]

Going back to the Tierney paper--what they showed is that small changes in CO2 (280 to 400 ppmV) could make a model match the observations made by the paleoclimate community.  Despite what Tierney says, it does not say how easy it would be to convert from an interglacial to a warm climate. 

What impresses most paleoclimatologists is how long it takes before a change happens. Glacial-interglacial cycles happen because the world with northern hemisphere glaciations have two endpoints (cold and warm) that are hard to move past.  We are currently in a low albedo interglacial, so it is unclear how long and what CO2 will be needed to drive the world to the Pliocene state.

I just wanted to add a final point of information.  The PRISM (Pliocene Research, Interpretation and Synoptic Mapping) interval was chosen when the Central American Seaway was essentially closed and the Bering Strait was open, but before the initiation of Northern Hemisphere glaciation. Tectonic reconfigurations of ocean circulation are minimized.  Here's a recent report that will allow tracking back:
https://pubs.er.usgs.gov/publication/ofr20181148

https://pubs.er.usgs.gov/publication/ofr20181148
 

[DrTskoul]

Yeah, the problem is that deglaciation or glaciation, requires the natural venting or sequestering CO2. Those rates initiate and grow much more slowly than the venting we are experiencing right now. Initiation can span a rather large time interval.  We dont have the ability to measure such minute changes with confidence.