|anthropogenic global warming, and ocean acidity
is one in
a series of briefing documents investigating the indicators,
science, analysis and argument surrounding global warming.
One of a grouping of documents on global concerns at abelard.org.
|on energy||on global warming|
housing and making living systems ecological
sustainable futures briefing documents
|Tectonics: tectonic plates - floating on the surface of a cauldron|
Humans love patterns. They seek to simplify the world, which allows them to manage without doing too much thinking or counting. Their simple machines are manufactured to go round and round and round on fixed tracks, like the motor in a car. Humans have tried to apply simple models to the universe in order to simplify, thus the sun goes around the Earth in 365 days. But, of course, it doesn’t, it goes around the sun in 365¼ days and a little bit, and a little bit of that. And then, of course, that timing varies ever so slightly over the millennia; and that little bit of variation starts to mount up over a billion years.
Then, as humans learn more, they learn about variations within variations, as you will see in the Milankovitch cycles section. They look at a few ice ages and think maybe the Milankovitch cycles caused them, so for a century or two they struggle valiantly to make these two things fit together. Every time, a bit more information makes the fit not quite so tidy. Month by month and year by year, our understanding of ice age data increases. The more data we gather, the more untidy the real world looks.
Very small changes in the path of a Mars shot will expand to millions of miles by the time rocket reaches its destination. Very tiny (accidental) differences to where a seed falls in a forest can determine whether the seed becomes a 200-foot giant, or is eaten by a squirrel. Small differences can determine whether a species survives and thrives, or is never heard of again. Small changes can determine whether a tornado gathers and accumulates, finding a path to New Orleans, or whether it peters out in mid-ocean, or takes a slightly different route to a less annoying landfall. Neither do we know much at all what starts or stops an ‘ice age’. Very possibly some trivial or accidental process goes into positive feedback, this leaves plenty of work for the future.
We still struggle to forecast weather a few days ahead, let alone understand a world of hundreds of thousands of years ago - or billions of years - from a few ice or sediment core samples. This is the real world, and the real world of advancing modern science. It is not a world of certainties or a few easy patterns. But despite all these uncertainties, we do expect the sun to rise in the morning and we do believe that we have a reasonable grasp on anthropogenic global warming. Do not become confused between areas of knowledge where we are not completely blind and areas where much that is written is bordering on hubris and speculation.
Human knowledge comes on a scale of knowing rather a lot about rather a little, to knowing very little about rather a lot. It is sane to keep constant awareness of whether you are in the shallow end of a heated swimming pool, or in the middle of the North Atlantic during a raging storm.
Flat earthers make up all sorts of speculative reasons why “there is no anthropomorphic global warming” [AGW]. Many of these ‘reasons’ are based on poorly grasped comments from sloppy fossil media and web sources. The purpose of this subsidiary briefing document is to provide the means for you to follow up these specious claims in more detail, should you wish. There is a great mass of discussion in books and appropriate journals, and increasingly upon the Net.
In a sense, this subsidiary document is a review of the elements that are not primarily emphasised as being relevant to modern anthropogenic global warming concerns!
There is most definitely anthropogenic warming.
But we still do not know many of the details. While the consensus is strongly that AGW is a reality, it should be kept in mind that a limited amount of global warming may prove to be a net benefit.
So, moonbats write all sorts of nonsense attempting to
‘be different’ and suggest all manner of mechanisms
whereby AGW is not happening,
Here is an example from the Cato Institute, which is often dubiously supported by all sorts of industrial interests that would rather not change (or pay for) their filthy externalisation of costs.
But there is still that awkward problem - reality!!
There is real global warming with considerable empiric evidence -
the world is getting hotter.
So the moonbats must make all manner of claims that it is really about the sun’s output changing or 101 other excuse-me’s.
Now, every adequate scientist knows full well that, with complicated systems, establishing causal links is no cake-walk.
But when sane scientists see two phenomena tracking each other, they tend to try to work out if there is a linkage.
Meanwhile special interests, for instance the cigarette industry, struggle for decades to dismiss the ever-growing links between illnesses and tobacco.
Or the media industry tries to deny a link between violence on film and violence in the playground.
Or the filthy fossil fuel companies struggle to dismiss any links between their filth and global warming.
But, back to that pesky reality again. The filth also kills millions right now.
Meanwhile, the West is increasingly dependent on a backward area of the world for energy, an area which is also a source of considerable current aggravation.
Among other lies spread by the nay-sayers is the claim that global warming scientists claim more than they know. This is a good way to pretend that there really is ‘no problem’.
But, in fact, serious climate scientists make no such claims.
It has taken decades to bring responsibility home to the tobacco drug pushers, and it ain’t over yet.
We have still a way to go before bringing responsibility home to the media corporations.
How long before sufficient causal evidence is deemed enough to force responsibility on the filthy dangerous fossil fuel industry?
Meanwhile, back in the real world again, planetary temperatures
But of course, we can’t really be certainly sure, can we? Maybe it’s all to do with university grants, or mickey mouse!
“The most prevalent reasonably scientific question
about current climate changes is ‘how do we know
that this isn’t natural variability?’.
But this is expected to change:
It remains that we do not know well how all these effects will pan out in the long-term regarding cloud cover and so on. However, we do still know the planet is warming, and we do still believe the main effect is identified.
Nobody sane denies that there are uncertainties, there are uncertainties in virtually all human endeavours. However, of the elements listed, the view is that GHGs have the greatest effect.
pressing reasons for action
There are other pressing reasons for controlling fossil fuel filth. There are pressing reasons for reducing dependence. The probability/consensus is that the greenhouse gases are highly relevant.
The arguments for greenhouse gases are far from ‘weak’. They are the most understood effects by a long march.
Perhaps doubters are confusing the level of knowledge of GHG warming contributed to heavily by human activities, with the smaller uncertainties elsewhere.
Increasing quantities of ice-core samples are being obtained. The diagram to the right shows a composite.
The first ice cores were extracted in 1956 to 1957, with techniques that have been steadily advancing since then. Early cores only went back less than 100,000 years, which is less than one glaciation cycle. Ice cores now go back 10 to 20 times further, back to 750,000 years (Vostok). However, their latest cores have not been fully analysed back to the beginning.
Ice core samples provide historic data of the earth’s temperature and its atmospheric composition. There are also (interrupted) sediment core samples that go back as far as 200 million years. Earlier cores were about 3-400 metres long, and the latest are over three kms long. For more on dating.
The atmospheric load for both carbon and methane is now much higher than has been seen during the last 650,000 years, as determined through examining ice cores.
A major part of the analysis of ice cores is checking the 16O/18O ratio. This gives an estimate of how much water is tied up in ice at any time.
According to the analyses, twenty thousand years ago, the sea-level is estimated as being 120 metres below the present sea-level. Today, the equivalent of another 80 metres is still being held in ice sheets, most of that being in the Antarctic.
There is constant talk of a medieval cooling period and suggestions that this does not fit the overall data. Evidence has now been found - by looking at marine fossils in sediment cores - that that cooling was probably only local to Northern Europe and may be related to a weakening of the Atlantic Conveyor. It could even be argued that the growth of the industrial revolution has offset cooling.
There was also, probably, some cooling in the three decades from 1950 to 1980. General acceptance is this was a cooling affect from dust/aerosols halted by multiple clean air acts in the West, when faced with deteriorating air quality (smogs).
I have seen recent claims from probably unreliable sources that ice core analysis shows a lag of several hundred years between the warming or cooling, and the changes of carbon dioxide trapped in the ice. For the moment, I believe that this is an error in understanding among those making the claim. The general view, in the more academic sources, appears to be that the carbon dioxide and temperatures track each other very closely, so closely that no such distinction can yet be made.
However, ice is laid down and slowly compacts as, year by year, more snow is precipitated on the top of the ice sheet (or glacier). There are minute spaces between snowflakes and within the firn, prior to the mass being so compressed that air communication with the outside world ceases. This process can take several hundred to a thousand years. Thus the air (including the CO2) analysed in the ice can be several hundred years younger than the ice in which it is entrapped. My guess is that those making a claim concerning time lags are, in fact, confused by this anomaly.
This excellent slide presentation [71-page .pdf file - 3.9 Mb] provides more detail on the general discussion than does this current briefing document, which focuses more on particular aspects. The .pdf document comes from one of the world’s premier weather research units.
Warming and sea-level rises are projected to continue increasing for at least another century, due to present levels of anthropogenic greenhouse gases [AGHGs]. Warming is not expected to the same level all around the planet. While average temperatures are rising and expected to rise further, there may still be highly variant local temperatures that are not directly related to AGHGs.
Keep this constantly in mind when you hear confident assertions and sound bites.J
Here is a none-too-clear description
of temperature measurement in ice-cores.
Note: methane is adjudged to remain in the atmosphere for much less time than CO2, that is approximately 14 years against an ‘indeterminate’ time.