THOUGHT EXPERIMENT: Some 70% of people, depends how you ask, accept the global emergency. Climate system destabilisation is one aspect, declining biodiversity and increasing pollution is another. I ask: what would actually *break* if humanity responded decisively? 1/

Climate: a decisive response = cap on fossil fuel extraction and planned phase out. Fewer private car journeys, less electricity. Nothing would *break*. We still live and eat. There are alternatives and we can all cut back and share more. So what are we afraid of breaking? 2/

Pollution: reducing the above helps all that, cracking down on pollution and biodiversity loss will reduce materials consumption but changing and sharing we can still live on the planet. What would break? 3/

Most pollution and resource consumption is done by rich people. Billions of poor people live and thrive so the rich can too. Nothing will *break* there? 4/

Of course, a rapid reduction in resource consumption, less of most things and enough of the essentials for everyone will *break*something. Economic growth for one thing. But if that broke, what would *break*with it? 5/

THREAD: Understanding pivot. Growing pressure from world population life-style will reach a point where it is damaging the capacity of Earth systems to an extent where life support will be challenged. It is simply a question of at what stage governments act. 1/X

Pivot is the same at each point 1-4. I use the STOP acronym. a) Stop, or halt, all increase of extraction/drawdown. b) Think, plan measures that will restore Earth system capacity and keep delivering basic services. c) Organise, re-work old regulations and agencies and then 2/x

Proceed to act. Notice that pivots are different depending on where measures are set in. It is MUCH harder to change when carrying capacity is challenged to an extent where people are dying. However, the pivot idea is a useful decision framework as you will see in 3/x

Pivot planning will be informed by three different criteria:
-which societal services and Earth systems are involved?
-how well is the societal system performing now?
-what drawdown stage has been reached? For example: 4/x

Water: FAO identify five levels of water extraction stress. Measures introduced in the light green countries will be far different than those in high stress areas. That is one dimension for pivot but not sufficient. The other level is societal performance. 5/x

TAIL RISK THREAD: A tail risk is one that is small but devastating. When an 8 year- old asks about crossing the road to get to a bus stop you correctly point out that there is a 1% risk she will get run over. However you might want to suggest instead 1/x

A 3-min walk to the traffic lights and crossing. To frame tail risk you include probability distribution of the event (car colliding with girl), with an outcome function (girl likely dies if hit), and account for the cost of mitigation (3 minutes to walk to traffic light) 2/x

In the realm of climate change, climate scientists are the ones charged with estimating the event risk, while other disciplines (e.g. economics, engineering) must be brought to bear on estimating outcome, and the costs of mitigating the risk or adapting to it. 3/x

In climate change there is a 5% chance of the Earth's temperature staying stable. And 5% chance it runs away to 4,6 degrees and mass die-off. We need a multi-perspective method to frame a risk response. What would that look like? 4/x

We cannot ask climate scientists to be truthful about the risks and then call them alarmists when they describe the tail risks. We need to create that space where the nexus of science, technology, social science and economics can meet to have a sensible discussion 5/x

THREAD: Last-Century thinking got humanity into a mess. It worked well though, just too well. Into the third decade of the new century and I am sad to see how little last century thinking is being named and challenged. 1/

OLD THINKING: Take that nature, use that nature. Same amount of land that we stated with, but going on four times the population and much soil erosion behind us. NEW THINKING: use it, put it back, regenerate it. 2/

OLD: Either you are good or bad. Promoted on almost every TV show. Reality is, we created a system and it grew and that system brings out the worst in us to an extent we have forgotten how to bring out the best in each other, almost. 3/

OLD: If you have money you should spend it on what you want. A few people had cars back in the 1920's. Now there are so many on the Earth that they alone can push the climate over the tipping point. NEW: Money should never give you the power and right to commit ecocide. 4/

OLD: the power in the economy is consumption. Using stuff up. Problem is, we are already using more stuff than our earth-society-earth can sustain. Successful ideas like that end badly when there is more human stuff on the earth than natural. 5/