The 5 Big Climate Unknowns?

[prokaryotes]

I went and made a video on what I think are The 5 Big Climate Unknowns.

Climate unknowns include the rate of sea level rise, ozone loss, how the Gulf Stream will react and what it possibly means, the Earth's response, and the potential for extra methane release from methane clathrates, stored at continental margins. There are many more climate unknowns, for example elaborated in this article https://thinkprogress.org/what-are-the-unknown-unknowns-of-global-warming-1438d934bdee

http://www.youtube.com/watch?v=mIrnJwMPzY4

I would be interested if you think there is an equal unknown, such as Mountain Pine Beetle infestations, destroying carbon sinks. What would you have added, or think is missing?

[johnm33]

How far south will the Arctic Ocean extend when the permafrost all melts? Hudson Bay?

[rboyd]

I feel that the El Nino/Nina cycle provides a great tool for seeing into the future (next decade) as the short term temperature spikes give us a taste of what will happen as the temperature trend hits those spike levels.

The soil/forest carbon turnaround during the last El Nino is extremely worrying, as it seems to show that somewhere between 1.5 degrees and 2 degrees we will get big moves from carbon sinks to carbon sources - negating any anthropogenic reductions (I silently laughed as I wrote those last 2 words given the recent jump in Chinese emissions).

Some of these feedbacks can become self-driving, even if temperatures fall back. The loss of forest leads to reduced rainfall, the microbes that digest the organic material in permafrost are exothermic etc. So a big unknown is whether an El Nino event could kick off feedbacks that continue during the Nina part of the cycle.

I also see the feedbacks as being highly connected, with one of them kicking temperatures to the point where another feedback kicks in. The finding that climate sensitivity increases with temperatures lends some support to this view.

[prokaryotes]

Two unknowns possibly worth a look is the ocean acidity increasing regarding both the the death collapse of coral reefs (circa 2050) and the impact on small deep ocean species eg planktons and their connections with the entire ocean life cycles. and therefore food sources. Included in this is the somewhat interconnected timing of oxygen death zones in the seas and oceans.

Indeed, probably have to make an update with the top 10 unknowns.

[Sciguy]

Sensitivity (usually measured with respect to a doubling of the CO2 concentration).

Rate of heat mixing from the ocean near surface to the depths.

Impact of reduction of aerosols as fossil fuel use decreases.

[Tom_Mazanec]

Looks like one unknown is turning out bad...how good a carbon sink the Southern Ocean is:
https://www.sciencenews.org/article/southern-ocean-antarctica-absorbs-less-carbon-expected