Manage your expectations about the benefits of emissions cuts, study says - Ars Technica

The climate is sometimes compared to a huge ship, in that it takes some time to turn it in a new direction, meaning that actions to limit global warming produce very gradual results.

The new study checks the usual scenarios with a slightly different methodology but also zeroes in on what it would look like to reduce individual gases (like methane) against a backdrop where other emissions aren’t reined in as quickly.

All this means that it’s difficult to evaluate a short-term temperature trend record and confidently state what it would have looked like with slightly higher greenhouse gas emissions.

They then used a much simpler model that could quickly simulate the temperature trends in many different scenarios of emissions of greenhouse gases and aerosols between 2020 and 2100.

First, the researchers compared broad scenarios of emissions—low, medium, and high scenarios that represent warming ranging from less than 2°C by 2100 to over 4°C at that time.

But given that the world is currently on track to stay south of that high emissions scenario, the medium vs.

The researchers also ran scenarios where a single type of pollution was reduced while other emissions followed the medium scenario.

For CO2, methane, nitrous oxide, sunlight-reflecting sulfur aerosols, and sunlight-absorbing soot, they simulate the effects of dropping emissions to zero, dropping them five percent each year, and dropping them to their pathway from the overall low emissions scenario.

Things like methane and soot are a little more interesting.

Methane does produce more warming, pound for pound, but it breaks down in the atmosphere, turning into CO2 and water vapor.

Just as climate scientists undertake studies to see if warming trends or extreme weather events can be attributed to human-caused greenhouse gas emissions, there will (hopefully) soon be a need to analyze the effects of emissions cuts.

These are expectations that need to be clearly explained and communicated to policy makers, and to the public, if we wish to avoid a backlash against perceived ineffective mitigation policies.” In the meantime, they point out, we’ll have to keep our eye on other metrics, like emissions trends and concentrations of the greenhouse gases that continue to accumulate in the atmosphere.