Tier 7 — Frontier
The interesting question is not whether a rebuilt civilization could reach this point, but whether it would repeat the same sequence — and which of the shortcuts available to a second attempt are real.
7
Frontier
Reach the point you started from — then decide, deliberately, what to do differently.
Energy used: about 230,000 kcal per person per day, Cook's technological stage (AD 1970) · where civilization stands
Binding constraint. The binding constraint is no longer technical. Everything in this tier is a choice about coordination, incentives and time horizons. The failure modes are institutional: extraction outrunning replacement, knowledge held privately, and short-term decisions with century-long consequences.

t7-energy
Reach an industrial energy supply that does not have to be paid for twice.
Energy
Guide ×5Sheet ×21

t7-shipping
Move the world's goods by sea safely and with falling emissions, and build and equip small boats to the standards that keep their crews alive.
Transport
Guide ×2Sheet ×11

t7-aviation
Fly people and goods with the safety of today's airlines, fly drones within the rules, and cut aviation's emissions.
Transport
GuideSheet ×8

t7-institutions
Build the machinery that makes the other steps hold.
Society
Guide

t7-choose
Use the one genuine advantage a second attempt has: hindsight.
Society
Guide ×2

t7-cea
Grow leafy greens, herbs and transplants on stacked tiers under electric light, with the electricity per kilogram worked out before building, and the room held safe for the people working in it.
Food
Guide
Lettuce about 24 °C by day and 18 °C at night
Light, temperature, humidity and CO₂ logged and held to set points around the clock

t7-farming
Raise yields on the land already farmed while cutting the nitrogen, water, methane and soil each tonne costs, and stop losing the harvest after it is grown, each change measured on the farm.
Food
GuideSheet

t7-city
Build and renew neighbourhoods to UN-Habitat's five principles, with public transport and open space within a short walk of everyone, and plan, measure and report disaster risk against the Sendai Framework's targets.
Settlements
Guide
