To answer William's question (assuming you mean surface air temperatures) I’d say
never. If the relatively flat trend over the last 11 years (David has it as 18 years, 1 month based of one selected dataset) were to continue at the elevated level it is right now (nearly 1.5F over pre-industrial years), the harm we are causing to earth’s habitat would continue to sink in for centuries with increasing extreme weather.
To answer my question, about shutting me (and concerned climate scientists) up, I’ll give 3 criteria that would indicate to me that we do not have to fret over global warming anymore.
1) The surface air temperature reduce down to a temp anomaly of 0.0 or less (relative to the base period 1951-1980), only then can the climate extremes (hat waves, hurricane/typhoons, severe thunderstorms/flooding, drought, wildfires) be minimized to natural levels.
2) The ocean heat content anomaly reduce down to at least 2 x10 22 power Joules.
Then the ocean food chain and acidification would no longer be harmed. And the sea level would stop increasing.
3) The global cryosphere (glaciers, ice) stop melting also contributing to sea level rise and ending water supplies to many areas of the world.
That is my candid assessment of the state of the world that would shut this alarmist up. It considers all three “spheres” that have been influenced by ghgs (air, ocean, cryosphere). We have a long way to go.
It is not as simple as just having the surface air temp staying at it’s current trend (as you might be thinking William).
Informed by Data.
Driven by the SPIRIT and JESUS’s Example.
Promoting the Kingdom of GOD on Earth.