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What-If

Explore what could change.

Choose a place, a documented issue and one of its documented interventions, then set how far it goes.

ILLUSTRATIVE SCENARIO — NOT A SCIENTIFIC PREDICTION. Built from documented causes, impacts and solutions plus general qualitative patterns. It contains no modelled numbers.

3 · Intervention
PilotScaledTransformative

Adopted across much of the area, with dedicated budgets and enforcement.

Illustrative scenario

What if Germany took a scaled approach to “Decentralised rainwater management”?

Starting point · documented

ClimateSeverity: Moderate
Heat, drought and Berlin's sponge city approach

Hotter, drier summers and heavy downpours are prompting Berlin to keep rainwater in the city.

The intervention · documented

Decentralised rainwater management

Green roofs, swales and infiltration on development sites.

Reduces runoff and supports cooling.

Schematic direction of change

Adaptation reduces exposure and harm, but the underlying hazard continues to be shaped by global greenhouse gas emissions.

Schematic, unitless illustration: relative pressure over time without the intervention compared with the intervention in place. Not based on measured data.NowLonger term →Relative pressure (unitless)
Without the intervention With the interventionSchematic shape only — no data, units or dates.

Causes this could address

  • Sealed surfacesBuilt-up areas prevent infiltration and heat up.

Impacts that could ease

  • Heat stressHot periods affect older and vulnerable residents.
  • Tree and forest stressDrought weakens urban trees and forests.

Wider reach at higher intensity is an assumption of this illustration.

How change might unfold

  1. Near term

    Early warning and preparedness measures can reduce harm quickly.

  2. Medium term

    Infrastructure and urban design changes reduce exposure as they are built out.

  3. Long term

    Protection must keep pace with a hazard that continues to intensify unless global emissions fall.

Faded stages are less likely to be reached at scaled intensity.

What this would not change

Local action cannot stop global warming; without global emission cuts the baseline pressure keeps rising.

What it depends on

  • Sustained funding and institutional capacity
  • Consistent enforcement and monitoring
  • Local stakeholder support
  • Participation of affected communities

ILLUSTRATIVE SCENARIO — NOT A SCIENTIFIC PREDICTION. Built from documented causes, impacts and solutions plus general qualitative patterns. It contains no modelled numbers.

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