Is it too late to reverse climate change?

Is reversal still possible? I'll check the latest science on what can — and can't — be undone.

No — it is not too late, but we cannot fully reverse climate change to what it was before industrialization on a human timescale. The more accurate question is whether it is too late to avoid the worst effects.

What is already irreversible

> 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

Science agencies and the Intergovernmental Panel on Climate Change (IPCC) consistently say this:

•"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

•The climate change that takes place due to increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop

•Some climate-related damage to humans and ecosystems will be irreversible, and some could be partially reversed with significant delay

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

Sea level rise from thermal expansion and melted ice sheets, ocean acidification, loss of species, and changes to permafrost are examples that would persist for centuries to millennia even if emissions stopped.

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

What is still reversible — or avoidable

The IPCC states that urgent and immediate action is needed to avoid the worst impacts, and issued a "final warning" message: act now or it will be too late.

But it also says it is not too late to act:

•We're not too late to avoid passing 1.5 °C, but the greatest threat is apathy

•The IPCC confirms that there is no "tipping point" for the planet as a whole

Instead:

> With every additional increment of global warming, changes in extremes continue to become larger. The reverse, then, is also true: every bit of warming we avoid will reduce the extremes of climate fluctuation. In other words, every bit of carbon we capture matters. It will never be too late to take action for the climate

NASA makes the same point:

> every little bit of avoided future temperature increases results in less warming that would otherwise persist for essentially forever

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

And while we cannot stop global warming overnight, we may definitely slow the rate and extent of global warming by reducing human-induced emissions of greenhouse gases

Scientifically, net-zero does work:

> "The report does really show – scientifically and robustly – that net-zero does work for stabilizing or even reducing surface temperatures," stated IPCC author Prof Piers Forster

The IPCC report also stresses the fact that the worst-case climate-related disasters are not inevitable and every half degree of lesser warming can ultimately make a huge difference

What would it take to limit warming?

Without major action to reduce emissions, global temperature is on track to rise by 2.5°C to 4.5°C by 2100

To keep warming around 1.5°C above pre-industrial levels:

> to limit global warming to around 1.5C, the global greenhouse gas emissions would have to peak before 2025 at the latest and be reduced by 43 percent by 2030
> the world needed to achieve net-zero carbon emissions by 2050

The IPCC says reducing present emission levels to at least halve by 2030 is possible with options in all sectors, which will require major transitions in the energy sector including a substantial reduction in fossil fuel use, widespread electrification, improved energy efficiency, and use of alternative fuels

So is it too late?

•To return to exactly the pre-industrial climate in our lifetimes? Yes, that is too late — some warming and damage is locked in.

•To reverse the trend of increasing warming and eventually bring temperatures back down? No — if we reach net-zero and then net-negative emissions, temperatures can stabilize and then slowly decline, as soils, ocean and vegetation keep absorbing CO2.

•To avoid catastrophic, worst-case warming? No — but the window is rapidly closing and requires immediate, large-scale action.

NASA describes responding as a two-tier approach:

> "Mitigation" – reducing the flow of greenhouse gases into the atmosphere
> "Adaptation" – learning to live with, and adapt to, the climate change that has already been set in motion

In short: We can't undo everything, but every 0.1°C of avoided warming reduces extreme heat, drought, floods, sea-level rise, and biodiversity loss. It will never be too late to make it better than it would otherwise be.

Citations (3)

1nasa.govGovernment
Is it too late to prevent climate change?
Backs: “The more accurate question is whether it is too late to avoid the worst effects. What is already irreversible. Humans have caused major climate changes to happen already, and we have set in motion more changes still”
2terraformation.comNot yet classified
Forests, Carbon, and Climate Change: Here’s What the IPCC Report Said
Backs: “But it also says it is not too late to act: We're not too late to avoid passing 1.5 °C, but the greatest threat is apathy”
3climatefactchecks.orgNot yet classified
Not too late, we may still slow or even reverse global warming
Backs: “every little bit of avoided future temperature increases results in less warming that would otherwise persist for essentially forever. But it may not be too late to avoid or limit some of the worst effects of climate change. And while we cannot stop global warming overnight, we may definitely slow the rate and extent…”