What is a wedge?

What a wedge means

A wedge is a building block of climate change mitigation. A wedge from any strategy has the same scale, whether it comes from building nuclear reactors or eating less meat. Each wedge ramps up linearly from nothing in 2020 to saving 2 billion tonnes of CO₂-equivalent in 2050. In total, each wedge amounts to 30 billion tonnes avoided over those 30 years.

Emissions savings are counted in CO₂ equivalent, covering all greenhouse gases. This includes emissions that occur upstream from fuel production, and from the electricity needed to power strategies (like electric vehicles or heat pumps). It excludes embodied emissions in new capital and infrastructure.

Baselines and additionality

To bend the emissions curve down, you must start with a baseline pathway: what will happen if we don't act.

By default this is the 'Current Policies' scenario that reflects the actions that governments around the world have committed to. Countries might back-track on their pledges, or progress on some solutions may stall - so you might want to explore what is needed relative to a 'No Policy' counterfactual, or anywhere in between.

For any wedge, deployment must be additional to that which occurs in your chosen baseline scenario. Solar power and electric vehicles are being deployed rapidly already, so acheiving a wedge of them means going even further.

Using the wedges

To build a pathway, start by deciding how many wedges you want to achieve relative to your baseline. The number of wedges you choose will determine how far the world will warm in the future: see the next section on relating wedges to warming.