Is it too late to reverse climate change?

Is it too late to reverse climate change? I'll check the latest science on what can still be turned around.

No, it is not too late to limit and ultimately reverse much of climate change, but it is too late to return quickly to a pre-industrial climate and some changes are already locked in for centuries to millennia.

1. Some warming and impacts are already irreversible on human timescales

> Humans have caused major climate changes to happen already, and we have set in motion more changes still

> While the effects of human activities on Earth's climate to date are irreversible on the timescale of humans alive today

Key science findings:

•“A large fraction of climate change is largely irreversible on human time scales,” the most recent assessment report from the Intergovernmental Panel on Climate Change (IPCC) warned

•A pioneering NOAA study shows how changes in surface temperature, rainfall, and sea level are largely irreversible for more than 1,000 years after carbon dioxide (CO2) emissions are completely stopped

•Even if human emissions of CO2 were cut to zero today, there is an inertia in the climate system that would continue for hundreds to thousands of years as the system attempts to re-equilibrate

•It could take as long as 1,000 years after a complete halt of greenhouse gases for environmental measures like sea level and ocean surface temperature to return to pre-industrial levels

This is why scientists say:

> Completely reversing climate change overnight is not possible. However, we can significantly reduce its impacts by lowering greenhouse gas emissions and restoring natural ecosystems

And why tipping points matter:

•Greenland ice sheet collapse risks irreversible meltdown at 1.5°C, committing the world to several meters of sea-level rise over centuries

•Even temporarily exceeding 1.5 degrees Celsius before bringing temperatures back down — a scenario known as an "overshoot" — could cause sea level rises and other disastrous repercussions that might last millennia

Even new research showing carbon dioxide removal can eventually reduce temperatures warns:

> Taking carbon dioxide out of the air won’t be enough to stop the harm caused by rising temperatures

2. It is NOT too late to stop it from getting much worse - and to stabilize the climate

> The short answer is that it's not too late to act, but our past actions may have already locked in certain outcomes and action is needed to avoid more substantial impacts in the future

NASA explains the dynamics if we act:

> if we stopped emitting greenhouse gases today, the rise in global temperatures would begin to flatten within a few years. Temperatures would then plateau but remain well-elevated for many, many centuries. There is a time lag between what we do and when we feel it, but that lag is less than a decade

> every little bit of avoided future temperature increases results in less warming that would otherwise persist for essentially forever. The benefits of reduced greenhouse gas emissions occur on the same timescale as the political decisions that lead to those reductions

The IPCC's conclusion from Climate Change 2021: The Physical Science Basis:

> strong and sustained reductions in emissions of carbon dioxide (CO2) and other greenhouse gases would limit further climate change. While benefits for air quality would come quickly, it could take 20-30 years to see global temperatures stabilize

NASA's current guidance is that:

> it may not be too late to avoid or limit some of the worst effects of climate change

Without major action, global temperature is on track to rise by 2.5°C to 4.5°C by 2100, but that trajectory is still a choice.

3. Can we actually reverse warming - make the planet cooler again?

Yes, in theory, but only with sustained net-negative emissions - not just reaching net-zero.

•Only if human emissions were “strongly negative over a sustained period”—for example, if tree planting and other activities were to sequester far more carbon than humans release—would climate change begin to be reversed

•A decline in global temperature would require sustained net-negative carbon dioxide emissions, meaning that human activities remove more carbon dioxide from the atmosphere than they add

•Offsetting these residual emissions is necessary to reach net-zero carbon, the only way to fully halt global warming... if successful, it could actually lower the Earth’s temperatures

This is why climate strategies now distinguish:

•Mitigation – reducing the flow of heat-trapping greenhouse gases into the atmosphere

•Adaptation – learning to live with, and adapt to, the climate change that has already been set in motion

And Carbon Dioxide Removal (CDR) options - like bioenergy with carbon capture and storage, ocean alkalinity enhancement, or ecosystem management - offer the possibility to support emission reduction and to provide net-negative emissions to reduce atmospheric CO2 concentrations in order to reverse a carbon budget or temperature overshoot.

Bottom line

•Too late to prevent all climate change? Yes. Major changes have happened and some will persist for 1,000+ years.

•Too late to reverse some impacts like sea-level rise and ice-sheet loss if we overshoot 1.5°C? For all practical human timescales, yes.

•Too late to act and change the future? No. It will never be too late to take action for the climate- every 0.1°C of avoided warming reduces extremes, and every ton of CO2 removed helps stabilize temperatures within 20-30 years if reductions are strong and sustained.

The next decade is viewed by the IPCC as the turning point for whether we limit warming to 1.5-2°C and eventually bring temperatures back down through net-negative emissions, or lock in irreversible tipping points.

Citations (2)

1nasa.govGovernment
Is it too late to prevent climate change? - NASA Science
Backs: “No, it is not too late to limit and ultimately reverse much of climate change, but it is too late to return quickly to a pre-industrial climate and some changes are already locked in for centuries to millennia. 1. Some warming and impacts are already irreversible on human timescales”
2nasa.govGovernment
NASA Jet Propulsion Laboratory Blog | Ask the Expert - Is It too Late to Reduce Climate Change?
Backs: “A pioneering NOAA study shows how changes in surface temperature, rainfall, and sea level are largely irreversible for more than 1,000 years after carbon dioxide (CO2) emissions are completely stopped. Even if human emissions of CO2 were cut to zero today, there is an inertia in the climate system that would continue…”