Permanent ice is already melting, climate is already changing. Even if we completely stop emitting CO2 right now (which we can't), there would still be too much CO2 in the atmosphere for some time, leading to further heating and longer melting. Even if we were to remove all excess CO2 from the atmosphere right now (which we obviously can't), Earth would still be too warm and icecaps would continue to melt while global temperatures would slowly revert to normal.
We're doing none of those things; we're still arguing over whether we should do anything at all. Our inaction over the past couple of decades on this issue is going to have repercussions for the next centuries.
The issue right now is: how bad do we want things to get? We can't stop it anymore, but we may be able to mitigate it. I really really hope we can prevent the Eastern Antarctic icecap from melting, because that would truly be a disaster. When that melts, most major population centers will have to be evacuated.
I share your concern regarding the gravity of the situation, and that a whole battery of efforts need to be made in order to mitigate the effects of current global warming. But I wish intelligent people would refrain from supporting the notion that there is any kind of "normal" regarding the climate. There is no such thing.
We have enjoyed a climate favorable to humans (in many places) in the last 8000 years or so, which has really been an anomaly in terms of the geological record. And the notion that we can manipulate the climate forever so that cities can stay put where they happened to be built at some point has to go. It is not sustainable.
While I agree that that is true for a sufficiently long timescale, the rate of change that we force on the world right now does make it look like we're changing the normal.
And yup, we are changing that fast, not as fast as a supervolcano of the past or an asteroid impact but not so many orders of magnitude away from it, even more considering geological scales.
It's undeniable that the past 8000 years have been pretty good to us, and that's not going to last forever, but the impact we're currently having on the planet is much faster, and very likely to be larger and more dramatic than the end of the last ice age.
Do you have any data on this? If you look at how quickly things cool off at night, Earth's biosphere reaches steady-state thermal equilibrium over the course of a few days. Your claim is essentially that we've already set off an albedo forcing function that we can't stop, and which is also stronger than existing negative feedback loops. Seems unlikely to me.
"Even if we stopped emitting greenhouse gases today, global warming would continue to happen for at least several more decades, if not centuries. That’s because it takes a while for the planet (for example, the oceans) to respond, and because carbon dioxide – the predominant heat-trapping gas – lingers in the atmosphere for hundreds of years."
And for all the time that there's more CO2 in the atmosphere, the atmosphere will continue to trap more heat from the sun, and temperatures will continue to rise.
At night the temperature drops not due to a lack of CO2, but due to a lack of sunlight. If we were to be able to partially block the sun, or reflect significantly more sunlight back into space, we would indeed be able to lose heat more more quickly, but that would require engineering on a scale we've never done before.
So sure, paint the entire Earth white, but how? Or build a giant solar screen in space, but again: how? Besides, blocking sunlight will also have many negative repercussions.
Yes, if you can just shut off the sun for some time, we can definitely easily overcome global warming... ...
Albedo is important, being snide is not.
But warmer seas can also mean more evaporation, more precipitation and therefore more snow, higher albedo and a brake on rising temperatures, possibly even a new ice age. (It gets mentioned sometimes; an ice age is ironically a potential result of global warming.)
But it seems to me that effect will mostly be limited to higher latitudes. There's not a lot of snow around the equator, which receives the most sunlight.
But if we could somehow increase the Earth's albedo on a large scale, then that would absolutely have an impact.