Equitable emissions reductions under the Paris Agreement

The Climate Action Tracker (CAT) has updated its effort sharing methodology to reflect the increase of climate mitigation required to meet the Paris Agreement 1.5°C long-term temperature limit, and the most recent literature published about equitable emissions reductions and the most recent emissions trends.

• The updated CAT rating system has six categories: “Role model,” “1.5°C Paris Agreementcompatible,” “2°C compatible,” “Insufficient,” “Highly insufficient,” and “Critically insufficient:”
  • We have now divided our “Sufficient” category into two: “1.5°C Paris Agreementcompatible “and “2°C compatible.” The “2°C compatible” category refers to the 2°C goal adopted in Copenhagen in 2009, now replaced by the 1.5°C limit in the Paris Agreement. This provides an historical reference point and bridge to the Paris Agreement-compatible category rating.
  • We have renamed the “Medium” category “Insufficient” because countries rated “medium” would still require others to take considerably more action to keep warming below 2°C, let alone limit it to 1.5°C as required under the Paris Agreement.
  • Similarly, so many countries fell into the “Inadequate” category that it was difficult to differentiate between their levels of (insufficient) action. We have therefore divided the “Inadequate” category into two: “Highly insufficient,” (Japan, South Africa), and “Critically insufficient”—reserved for those taking the very least amount of action, such as the US, Russia and Saudi Arabia.
• We find that the main implication of including 1.5°C Paris Agreement-compatible scenarios in fair-share mitigation ranges is that, for many countries, the “Role model” category now requires increased mitigation efforts, as would be expected for moving to a more ambitious target.
• The overall impact of including the most recently-available data varies from country to country. For most countries, the effect of updated allowances in the Fair Share range did not lead to a change in the country’s actual rating.