Uncertainty in complex systems

Complex systems often exhibit feedback loops, as a change in one part of the system leads to (often unanticipated changes) in another part. Conceptual sketch of the climate system, IPCC AR4, WG1, FAQ 1.2 2007

Tipping points

What processes are out there which will only kick in once the system is far away from its usual state?

• Tipping points [UK "met" ( = meteorological) service]
• Beavers emerge as agents of Arctic destruction [NYTimes]
• Can plants prevent permafrost thaw? [University of Edinburgh]
• "Six large amplifying feedbacks" [Climate Emergency Institute]
• More on Paul's 'feedback' bookmarks.

The biggest unknown, unknown in the climate system...

The largest uncertainty in climate models

Nowadays, there is one factor which is involved in many of the most important feedback loops in Earth's climate system which

• may be the most important,
• the least well understood,
• the hardest to predict,

It involves the response of this part of the system to changes:

What will the humans do??

(Human) tipping points

This (human!) part of the system has exhibited many non-linear tipping points in the past,which were not foreshadowed at all in the time dependence of the data (translation: fast changes with little warning ahead of time).

• 
  From A History of Violence, by Steven Pinker
• "This is How Fast America Changes its Mind"

Industrial *Learning curves*

Consider this graph of what fraction of the U.S. population owned these kinds of things:

These curves are often exponential (non-linear) when a new product enters the market:

• Scaling up: A company's first product may be crude. But once they start selling, profits combined with competition often result in improvements, and price drops.
  1. A company sells a few units of a new kind of product, initially at a high price.
  2. they make a little profit, enabling them to invest in more efficient machines to produce their products, and more research,
  3. with greater efficiencies, they can sell more units,
  4. enabling them to invest in even more efficient machines...
• Social effects Some things... like telephones, are moree attractive the more people that are using them.
  
  Sometimes, people hear or see new devices of friends and neighbors Solar power is contagious - The neighbor effect.
• Learning curves apply primarily to Manufactured goods: In contrast, houses are built "in the field", as are nuclear power plants, and their prices have not continued to drop.

This has been happening with renewables:
CarbonTracker

It is now 'Cheaper to save the planet than to ruin it"!
CarbonTracker: Gain not pain summarized in their Political tipping point graphic.

Katharine Hayhoe: Two (very) human feedback cycles

Katharine Hayhoe is a curious climate communicator. She is also a Canadian, evangelical, climate scientist, UN "Champion of the Earth", professor at Texas Tech of Political Science and director of the Climate Center and more...

She points out two feedback loops related to how we process information on climate change.

[Which one is a positive feedback loop and which is negative?]

Fear and anxiety

Pro-climate social feedback loop

Instead, when we talk about climate change, the two most important things to focus on are: (1) how climate change is affecting things, people and places we care about, and (2) what we can do - individually, collectively, and globally - to FIX it.

-Katharine Hayhoe in "Saving Us, a climate scientist's case for hope and healing in a divided world"