Even if we take drastic action today, we won’t reap the benefits of a cooling planet until the mid-century.

Using climate model, researchers at the Norway’s Centre for International Climate Research probed hypothetical futures in which emissions of nine different industrial pollutants (e.g. CO2) , were either eliminated instantly or phased out at a rate of 5% each year, starting in 2020.

Key Study Findings

Key Finding #1: CO2 Emissions Eliminated in 2020 = Rate of Warming Slows in 2033

Cutting CO₂ emissions could slow the rate of warming as early as 2033, but only if they are ended worldwide in 2020 which is unrealistic as it would mean eliminating 80% of the world’s energy sources, including shutting down all fossil-fuel power stations, overnight—clearly not a realistic or desirable scenario.

Key Finding #2: CO2 Emissions Reduced at 5% p.a. starting in 2020 = Rate of Warming Slows in 2044

Reducing CO₂ by 5% per year, starting this year, would produce a statistically significant deviation from what temperatures would have otherwise been only in 2044.

Even at 5% that rate of CO₂ reduction is ambitious, on a par with the 4-7% drop estimated this year as a result of the covid-19 pandemic and widespread economic shutdowns.

Why the delayed effect?

CO2 Lingers In the Atmosphere for Decades

Carbon dioxide emitted today will remain in the atmosphere for decades to centuries before it is reabsorbed by vegetation and the oceans.

Natural variability in the climate.

Large-scale natural climate effects (E.g. El Niño and La Niña) play a role in warming and cooling the planet in a cyclical fashion by fractions of a degree. The Centre for International Climate Research took this into account.

Oceans Greenhouse Emissions

More than 90% of the energy trapped by the greenhouse-gas emissions produced in the past half-century has been stored in the ocean and released to the atmosphere as heat only slowly.

References:

1. Nature Jul 7, 2020 Edition; “Delayed emergence of a global temperature response after emission mitigation” Source: https://www.nature.com/articles/s41467-020-17001-1
2. The Economist Jul 11, 2020 Edition; “Emissions slashed today won’t slow warming until mid-century” Source: https://www.economist.com/science-and-technology/2020/07/11/emissions-slashed-today-wont-slow-warming-until-mid-century