Global warming - threat or benefit?

[stui magpie]

When I was recently in Darwin, the guy who was the guide for the kakadu tour I did is an archaeologist. He was fascinating to listen to as he could overlay knowledge of other other cultures he's researched with a scientific perspective.

When discussing how long Aboriginals have been in Australia and how archaeologists look to different evidences, he made the point that during the last Ice Age, 20,000 years ago, sea level was around 100m lower than today.

Let that sink in for a moment. 100 metres lower.

The reason he raised this was Aboriginal settlement occurred during the last ice age. With the sea level so low, many of the earliest areas that they inhabited are now under 50-100m of water, which makes it pretty frigging difficult to look for evidence of habitation.

Anyway, that led me off on a bit of research of my own, not into Aboriginal habitation, but into ice ages.

It seems there's a bit of a cycle over roughly every 100,000 years. Ice ages start when temperatures drop in summer in the northen hemisphere, the winter snow doesn't melt in summer but slowly turns into sheet ice. This increase in polar ice means sea levels drop (and salinity increases)and climate gets colder and drier with less rain.

Ice ages last for about 90,000 years (with a gradual lean in and lean out), with the warmer inter glacial period we're currently in only lasting around 10,000 years.

Can you imagine the impact of another ice age on a world population that has basically grown and thrived in the comparatively short period of 10-12,000 years? Whole tracts of land in the northern hemisphere would be permanently ice covered. A lot of that agricultural land currently used to grow food. Populations would potentially head to the equator where much of the worlds poor is already focused.

Vast tracts of new land would appear from under the receding water, but who owns this land? How usable would it be?

Now, it seems that we're about due for another ice age right now, but it seems that the increase of greenhouse gases in the atmosphere that first started around 5000 years ago with increased agriculture, is holding it at bay.

So, if all the efforts to reduce greenhouse gases is successful and the natural balance is restored, the result is likely another ice age sooner rather than later

Here's a good short simple article on the ABC

http://www.abc.net.au/news/science/2016-06-15/what-is-an-ice-age-explainer/7185002

Another slightly more complex in The Conversation.

https://theconversation.com/ice-ages-have-been-linked-to-the-earths-wobbly-orbit-but-when-is-the-next-one-70069

It's an interesting dilemma in a way. The last ice age lead to the spread of the human race across the globe. The last 10,000 years have seen incredibly advances compared to the 90,000 prior to that. (well, as far as we know anyway. Evidence of past technologically superior civilisations could be 100m under water for all we know)

What would another ice age do to the world? It would certainly put a big dent in the population, with the poorest being the first to be dented. You could expect war over habitable land and natural resources and the environment as we know it now would be very different impacting all plant and animal life.

The world as we know it has evolved in a 10,000 year window that it seems we are holding open, for better or worse, whether temporarily or long term (in geological time)

Should we try to keep it open or work to allow it to close and let nature do her thing?

[Skids]

Interesting thoughts Stui.

I stick by what I've always said, the global warming brigade is a farce, to think humans can some how control the planets climate is stuff more suited to fairy tales.

We will have another ice age, the question is when and no matter how much Al Gore and his money leeches try to tell us otherwise, we can't do a thing about it.

[stui magpie]

Controlling the climate is indeed the stuff of fairy tales or science fiction, but influencing or impacting it, isn't.

The Aboriginals terraformed massive tracts of Australia over 10's of thousands of years, changing both the environment and the climate to the point where parts of it now rely on regular intervention.

Greenhouse gases have in impact on temperature, I think that's a given, but they don't impact planetary rotation and wobble, or the varying intensity of solar radiation.

Plus, whenever you make a change to a closed system, it has consequences.

It seems clear to me from what I've read that increased greenhouse gases in the atmosphere coinciding with the increased civilisation of man during this warm period has impacted the beginning of the next ice age. whether that's a "permanent" thing (inverted commas because in geological time human settlement is not going to be permanent) or short term like 100 or 1000 years depends not only on the greenhouse gases but on all the other factors that we have zero influence on.

[Dave The Man]

[Mugwump]

It may be, but setting fire to your house is not a good way to deal with a cold snap that may come in across a hundred years.

[stui magpie]

^

Not sure I follow your logic there.

[HAL]

Does that remind you of it? ?

[Mugwump]

[stui magpie]

^

Did you read either of the articles I linked? Once the conditions are right for an ice age, it can start relatively quickly. One summer in the northern hemisphere where the snowfall doesn't melt is a trigger event. It then has a form of self fulfilment about it unless you get a hot burst that melts it. Once it starts it will creep south but not over thousands of years, more decades to get started.

As far as greenhouse emissions, we've been putting greenhouse gases into the atmosphere for thousands of years, really spiking upwards since the industrial revolution.

I don't think we have the ability to reduce greenhouse emissions back to what they were pre the last ice age, even if we stopped burning all fossil fuel. Agriculture plus over 7 million people breathing out CO2 and farting methane (even if those 7 million are all 2 legged carbon sinks) means we're producing greenhouse gases.

I suppose my point was, the overall equation isn't as simple as people like to think it is. We're due for another ice age, so rather than people spouting memes, we should all look at the bigger picture.

[Mugwump]

^ I read the first one, not the second, which I have read now. They are interesting, but I didn’t see either as indicating that substantial glaciationcould form over decades. There seemed to be lots of talk about thousands of years, etc.

Anyway, your point is a valid one, and the articles do make the interesting point that CO2 emissions may have delayed the onset of an ice age : but if CO2 concentrations are so powerful that the mere introduction of rice paddies 5000 years ago might have delayed an ice age, one still dreads to think what our present rate of emissions might be doing.

I think the idea of uncertainty is integral to most climate modeling and forecasting, and I too become impatient with people who are rapt in certainty on this issue. But since we cannot predict the effects, it still seems to me a very risky activity to emit large quantities of climate-changing gas in a very short time. The chances that the quantities we emit are lining up a sweet spot for human habitation seem infinitesimally small.

The other dimension of this whole question is how unviable human existence is, on a geological time scale. Whether from a super volcano eruption, an ice age, a hot age, the moon’s slow departure, or the sun’s gradual cooling and enlargement, one day our species will become extinct, probably after a vicious struggle for dwindling resources. As a fact, that is hard to contemplate.

[stui magpie]

^

Yup, when you look at it, more than 10,000 years ago humans were all pretty much tribal and had been for 100,000 years with little progress. All the progress has happened in a small window.

The human races grip on it's ongoing future is tenuous at best.

[Pa Marmo]

I’d be happy with some global warming here in Bacchus Marsh at 3am.

[roar]

[Skids]

[Pies4shaw]