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CDNEmpire OP t1_jb530sz wrote

Reply to comment by ParatusLetum in During the last ice age, how long would it have taken for the ice sheets to form? by CDNEmpire

So if we are still in an ice age, then the gradual increase in global temperatures is all part of that.

So where do scientists draw the line between the global warming caused by humans, and the global warming that’s part of the natural cycle of things?

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Syfer2x t1_jb5d0sr wrote

I think it’s actually fairly easy to do when you correlate the rise in temperature to a rise in human industrial activity. As a previous comment mentioned, these processes are slooooow, like reeeeaally slow. The insane spike in global temperatures since the beginning of the industrial age is far too sharp to be attributed to normal interglacial activity, which I believe technically we should be exiting anyways. We’re becoming overdue for another glacial period but are staving it off and then some just with our own activities.

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CDNEmpire OP t1_jb5m1p5 wrote

That’s fair. I mean we definitely can be helping things by speeding up, or even completely changing the natural process.

The natural balance will eventually be restored. Just a question if we’re still around to witness it

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Jewnadian t1_jb5mw2b wrote

That's not really a guarantee, it's entirely possible to push a planet into runaway greenhouse mode and it never recover to where carbon/DNA based life is possible again.

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GumboDiplomacy t1_jb5s6gl wrote

This is a good visual representation of climate throughout earth’s geological history. Notice how slow most of these changes are, a matter of a couple of Celsius change over millions of years. Then look at the change over the last 200 years.

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SgtExo t1_jb5yz1d wrote

Check out this helpful xkcd timeline, it is a bit old by now and we should be on the optimistic path, if not even a bit better depending on if green tech keeps getting adopted faster. But it is a good way of seeing how stable temperatures have been for the last 20 000 years.

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[deleted] t1_jb5hn6u wrote

Generally the SPEED at which the climate is changing is the problem compared to geological records from past ages similar to our own.

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Busterwasmycat t1_jb5ia6z wrote

Yeah, well, there is the nub of the argument, and a good part of the reason why most scientists accept that humans are affecting climate but many disagree about the importance of the human role. It is also where a lot of uncertainty appears in predicting into the future.

The problem is that there is no "signature" we can measure directly and say "this 23 % is from humans (pick any number), and the other 77% is what nature does".

What we have are climate models. The climate models are an attempt to imitate the natural system behavior, and seeing how different changes to input conditions cause changes to output. The system is complicated, and so are the models.

There has been a lot of work on trying to figure out how much change has been "forced" by human activities versus how much can be explained by natural changes. They can compare models with, or without, changes to various important parameters over time as an input, and see how the results differ, and then interpret what is really important and what is not so important for what is actually happening. Fairly complicated work in actual practice.

It is from playing around with the various parameters that can affect climate, and finding mismatch between observation and the changes that ought to have happened if nature alone is the cause, that a lot of climate scientists have concluded that CO2 is the main problem.

Are they right? We are finding out. Not sure it is wise to perform this experiment in real time, but we are, even if not purposefully.

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forams__galorams t1_jb9cmi2 wrote

> So if we are still in an ice age, then the gradual increase in global temperatures is all part of that

For the last 10,000ish years the Earth has been in an interglacial, ie. the least cold stage of an ice-age. Glacial-interglacial cycles have been occurring for the last 2 million years or so, which is the Quaternary Ice Age.

The increasing global mean temperature in very recent times is on top of being in the warmest part of an ice age, it cannot be attributed to part of the natural cycle. The natural cycle would be due to start cooling sometime in the next few thousand years and transition back to a glacial episode. Anthropogenic warming has eliminated that possibility and the fear is that the Earth could exit Ice Age mode entirely and switch into hot-house mode with virtually no ice at the poles at all, correspondingly higher global sea levels and a lot more energy in the climate system for extreme weather events to become a regularity.

> So where do scientists draw the line between the global warming caused by humans, and the global warming that’s part of the natural cycle of things?

Somewhere around the year 1900. Take your pick, determining an exact date is a bit of a moot point by now.

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