Earth spends most of its time in greenhouse phases.
"A "greenhouse Earth" is a period during which no continental glaciers exist anywhere on the planet... Earth has been in a greenhouse state for about 85% of its history.
"Earth is now in an icehouse state, and ice sheets are present in both poles simultaneously... Earth's current icehouse state is known as the Quaternary Ice Age and began approximately 2.58 million years ago... Earth is expected to continue to transition between glacial and interglacial periods until the cessation of the Quaternary Ice Age and will then enter another greenhouse state."
1: https://en.wikipedia.org/wiki/Geologic_temperature_record#/m...
The rate of warming in the last century is orders of magnitude faster than any natural geological warming trend. It is the mother of all hockey-stick graphs, conveniently drawn for us by Randall Munroe [0]. Note: you will need too scroll a lot.
The intention was to draw attention to the grand scope of the earth's history, and the rare climate in which we reside.
silicate rocks basically traps co2 over millions of years and causes temperatures to fall
As an aside, we need to dissolve roughly one large mountain into the mix layer (top ~50m) of the ocean to have it fully take up atmospheric CO2. Without dissolving, the reaction is very slow (co2 in atmosphere => slightly lower pH rain => reaction with mostly passivated rock + erosion).
The Story of CO2 taught me something I had never considered. It wasn't exactly that photosynthetic life started pumping out O2 and chilled the planet. Snowball earth happened way later. It was photosynthetic life that got buried in sediment and locked it away from aerobic respiration. The amount of carbon stored in the earth's crust is insane. Fossil fuels are just a minuscule fraction of that.
This has some implications for our current climate: If we want to use biology to sequester carbon (growing trees, algae, etc), it's only a temporary sink unless we lock it away for eons. Once it's eaten/burned, the CO2 is right back in the atmosphere. In short, we gotta physically put it back into the earth's crust if we want to draw down carbon.
https://www.ospo.noaa.gov/products/ocean/sst/contour/
I'm in western Europe and really hope the AMOC will not collapse.
Given time, humans and other animals will move toward the poles or toward the equator to find habitable zones. Put that on a rush schedule and everyone suffers.
All that matters is sociotechnological progress to be able to progress further enough to overcome these tests of existence.
Me too.
> and really hope the AMOC will not collapse.
It absolutely categorically will, probably in a decade or two.
However, as the rest of the planet rapidly warms, for a decade or so western Europe gets cooler and wetter. I only have 2 or 3 decades to live at best, so it's swings and roundabouts: some you lose, some you win.
This article is not about that.
Goodbye every single coastal city, air or sea port, industrial area, power plant, transport infrastructure in the world.
Medium term (high single-digit decades): rapid global warming pushing the habitable zones to the poles and sub-polar regions. Note, critically, that means agriculture, as there are no established ecosystems to hunt/gather from at the poles.
We are heading for ~7º C by the end of the 21st century. Never mind 4º, double it.
Long term (millennia): another mass extinction event, much as the previous ones. We're 75-80% of the way through already, though.
Geological terms...
Hundreds of thousands of years: if humans go extinct, the planet will recover in 100K years or so, with plentiful but severely species-impoverished ecosystems.
Tens of millions of years: lots of new species, new rich ecosystems form.
Hundreds: if another sentient species evolves, it will have a hard time bootstrapping an technological civilisation, as we've extracted most of the the easy-to-access resources.
where do you get that from? The wiki page of the glacier states 42mm rise in sea level in the next 100 years, worst case scenario. The wiki page of the ice sheet states 3 to 5 meter over the next 500-13 000 years.
Just fine. If the temperature would cooperate.
The land of the midnight sun actually has great yields for the few crops that tolerate the cool temperatures (low ground greens and vegetables basically, not staple grains or fruit). But because the season is so short temperature wise nobody really farms that stuff commercially up there.
Have you noticed that all broadleaved trees and shrubs lose their leaves for half the year in temperate zones already?
Did you not wonder why that is?
They'll be fine. Annual crops are fine. Wildlife is fine if it's got somewhere to migrate to.
Tough for wildlife when there's nowhere to migrate to, though. But what's burning desert in summer might be just about tolerable hot tropics in winter.
The problem is that current tropical species can't handle the alternation of the seasons. You don't get seasons at the equator. Spring/summer/autumn/winter is a temperate-zones thing. Near the equator the sun rises and sets at the same time every day, and there are at best 2 seasons: the dry season, when it never rains, and the wet season, when it rains a lot all the time.
The media also need to stop referring to CO² as just "carbon". That is misleading too. (You didn't to be fair.) Carbon itself is common in our environment and is even okay in many other compounds.
That's happened rather more times in Earth's history than most folks are comfortable admitting. Tunguska would have leveled any major metropolitan city on the planet. I still think an impact is one of the more likely initiators of the Younger Dryas abrupt cooling and worldwide ~100M sealevel rise ~12,000 years ago. Conspicuously aligned with the oldest surviving traces of city living, agriculture, etc. It's increasingly accepted that a large portion of human history is 100M underwater on the continental shelves, estuaries, and other coastal areas where humans would have liked to live.
Any references for that? Genuine question.
More:
https://www.pnas.org/doi/10.1073/pnas.1411762111
https://www.nature.com/articles/s41586-025-08769-7
https://www.academia.edu/9737879/Land_Beneath_the_Waves_Subm...
https://pure.york.ac.uk/portal/en/publications/under-the-sea...
It's possible the sea level rise could have initiated the cooling. But there is much disagreement as to what exactly initiated the de-glaciation which caused the sealevel rise.
https://www.weather.gov/ict/WBGT
https://www.psu.edu/news/research/story/humans-cant-endure-t...
UNIVERSITY PARK, Pa. — As climate change nudges the global temperature higher, there is rising interest in the maximum environmental conditions like heat and humidity to which humans can adapt. New Penn State research found that in humid climates, that temperature may be lower than previously thought.
It has been widely believed that a 35°C wet-bulb temperature (equal to 95°F at 100% humidity or 115°F at 50% humidity) was the maximum a human could endure before they could no longer adequately regulate their body temperature, which would potentially cause heat stroke or death over a prolonged exposure.
Wet-bulb temperature is read by a thermometer with a wet wick over its bulb and is affected by humidity and air movement. It represents a humid temperature at which the air is saturated and holds as much moisture as it can in the form of water vapor; a person’s sweat will not evaporate at that skin temperature.
But in their new study, the researchers found that the actual maximum wet-bulb temperature is lower — about 31°C wet-bulb or 87°F at 100% humidity — even for young, healthy subjects. The temperature for older populations, who are more vulnerable to heat, is likely even lower.
That's a problem at the Equator, but not at the higher latitudes.
The mad rush to get there would likely extract a heavy toll.
Rain patterns and extreme weather events are the things to really worry about. Temperature changes alone can be mostly dealt with by planting different crops.
Climate refugee situation will dwarf any war refugee issues. They claim "invasion" now, but this one will be an actual invasion.
Basically like how when people can't breath good you put them on oxygen to keep them alive only getting oxygen into the blood is the bottleneck rather than into the body.
That one may not be out of the woods yet.
Earth would have to experience > +35 to +50C for the poles to be uninhabitable due to heat.
Not reliably, not continually, and much less often when you dump enough energy into the atmosphere to disrupt major wind patterns.
British Columbia hitting 121°F/49.6°C at 50°N latitude would sort of suggest your generalization doesn't hold true anymore.
Here's a citation demonstrating that over the last 95 million years if you need one: https://www.pnas.org/doi/10.1073/pnas.2111332119
One more just for fun: https://journals.ametsoc.org/view/journals/clim/12/4/1520-04...
