Electric Car Drivel

[mikeey84]

Those two sound remarkably close.
I, for one, am not "opposed to the idea of ACC", but I do believe in the need of ongoing research and 'debate'. Some people seem to accept it as a 'certainty' that the burning of fossil fuels is the only factor bringing about climate change, and I strongly suspect that they are probably misguided/wrong in believing that is a certainty.

Fortunately, as witness the ongoing plethora of papers being published to which you refer, research (and hence potential 'debate') clearly is ongoing.

Kind Regards, John

ACC is clearly only caused by human activity, hence the "A" at the beginning. No one is disputing that CC occurs by other means.

 

[mikeey84]

I do not know what, if anything, that means, but it is an observation. I would imagine (but do not know) that 'natural processes' probably reduce that increase to appreciably less than that 0.0006% per year

2 points on that:
1) co2 is just one factor on ACC (methane being another)
2) I imagine you are correct, but outside of massive geological events the earth hasn't seen an increase in global atmospheric co2 levels as quickly as it is now in recent past (recent being 10s of millions of years) so expecting it to cope with that amount off co2 is optimistic to say the least.

Have you seen the Moana Loa chart for atmospheric co2 over the past 60 years? Or the ice core samples showing the massive increase? 0.0006 is a small number, but add together post industrial revolution years and it will soon add up (obviously every year won't be 28 billion, but cumulatively it's a huge increase)

 

[JohnW2]

ACC is clearly only caused by human activity, hence the "A" at the beginning. No one is disputing that CC occurs by other means.

Quite. That is what I am saying. Some seem to believe that "CC" is all "A", and that is what I very much doubt. Some even seem to think/believe that the only "A" is the burning of fossils fuels, and that is not true, either.

As I've said, the important question is how much of the "CC" is due to "A", and that is hard to be certain of, when we necessarily only have essential 'circumstantial' evidence.

Virtually all of the theoretical conclusions rely on drawing conclusions about causation from evidence of correlation - something which is always difficult/dangerous. I don't know if you saw it, but there was a recent discussion here (Yes, in an 'Electrics' forum!) about the possible causal relationship between historical atmospheric pollution with lead due to the use of leaded petrol and violent crime - again with the same problems. Whilst it is very logical and reasonable to think that changes in climate should, to a lesser or greater extent, be influenced by man-made CO2 emissions, that causal relationship is not 'proved' by the correlation between those two things.

Over the period during which climate change has been observed, there have been any number of things which have shown changes which would probably correlate fairly strongly with the climatic changes (e.g. progressive reduction in church attendance, increases in radio frequency emissions, increased ownership of electronic devices, etc. etc.) but most of those things 'clearly' do not have a causal relationship. Again, I am in no way suggesting that the "A" is not responsible for much of the "CC" - but I do think that we have a lot more to learn and understand about the big picture of climate change - and that is where the ongoing research (and the almost inevitable consequential 'debates') is required.

Kind Regards, John

 

[mikeey84]

and that is hard to be certain of

Meehl et al. (2004) took a different approach. Instead of projecting future surface temperature change, they used climate models to attempt to attribute past temperature changes in a method known as 'hindcasting' (as opposed to forecasting). In their study, Meehl et al. show that natural forcings cannot account for the increase in global temperatures in the second half of the 20th century, and that models using both natural and anthropogenic forcings model the temperature change over the 20th century most accurately.

A number of studies using a variety of different statistical and physical approaches have, like Meehl 2004, estimated the human and natural contributions to global warming. They universally find that humans are the dominant cause of the observed global warming over the past 150 years, 100 years, 50 years, 25 years, etc. In fact, many conclude that natural effects have actually been in the cooling direction in recent decades (Figure 2).

 

[JohnW2]

2) I imagine you are correct, but outside of massive geological events the earth hasn't seen an increase in global atmospheric co2 levels as quickly as it is now in recent past (recent being 10s of millions of years) so expecting it to cope with that amount off co2 is optimistic to say the least.

Indeed, and as you go on to imply, the increases in atmospheric CO2 levels over the past 60 years are a clear indication that the (whatever the cause of the increase), the natural processes have not (at least not yet) been able to 'cope with it'.

Have you seen the Moana Loa chart for atmospheric co2 over the past 60 years? Or the ice core samples showing the massive increase? 0.0006 is a small number, but add together post industrial revolution years and it will soon add up (obviously every year won't be 28 billion, but cumulatively it's a huge increase)

Yes, I'm familiar with the Moana Loa data, which shows something like a "28% increase" in atmospheric CO2 levels (from about 0.032% to 0.040%, by volume), over the period from 1959 to 2016.

However, without having any significant knowledge of the field concerned, I have no idea as to what effect on climate might be expected as a result in a change from roughly 0.03% to 0.04% - and there is, as far as I am aware, no way that can be determined 'experimentally'.

Percentage changes in small numbers are always difficult to interpret, and can appear dramatic even when of little importance - and the absolute level of atmospheric CO2 obviously hasn't changed all that much (i.e. if you plotted the Moana Loa data with an axis which went down to zero, the increase over the past 60 years would look much less dramatic).

Kind Regards, John

 

[StephenOak]

I didn't say human activity had caused GW, just that the evidence is clear that it has had a major impact. Approx 97% of climatologists accept this.

However you only get 97% if you have Diane Abbot type arithmetic skills.

The 97% figure come from work done by by Doran & Zimmerman of the University of Illinois at Chicago.

The used an online polling tool to ask 10,257 members of the American Geophysical Union (of whom 3,146 replied) a number of questions but there are only two that get talked about:
“When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?”
“Do you think human activity is a significant contributing factor in changing mean global temperatures?”

They whittled the 3,146 down to 77. Of them only 76 said 'risen' for Q1 and 75 said 'yes' to Q2. And 75/77 = 97.4%.

I don't think that 75/10,257 or even 75/3,146 is anything like 97%.

That totally leaves aside the fact that the second question is so vague as to be essentially meaningless. What is a 'significant contributing factor', 10%, 25%, 50%, 75%?


Also, in 1900 at least 97% of experts would have said that the continents were not moving, and they would have been wrong. In 1960 at least 97% of medics would have said that ulcers are caused by stress, and they would have been wrong.

Science is not a popularity contest. What matters is not how many people say something or how many papers are published on something. Scientists are people with, families, bills, etc - they will tend towards publishing work that fits the current funding vogue so that they can keep working. What matters is the facts.

A few key facts are that:
1. We have very little robust global data to work with.
The only close to global data is from satellites and that only goes back to the 1980s. Climate is normally defined as a 30 year average. So we have enough data to produce one reasonably reliable data point. Even that one data point has some caveats as some satellite instruments have gradually failed and satellite orbits have changed in ways that were not predicted which affected the way the results had to be interpreted.
2. Older data is very patchy. The oldest data set (Central England temperature) only goes back to 1659 or 1722 for the better data. In geological terms that is nothing and it only covers one part of England. Wider decent data (Europe, the British Empire, the US) only goes back to the 19th century.
3. Good ground level data is not available on a worldwide basis even today. Large chunks of Africa and Asia and both Polar regions are poorly covered.
4. Some of the ground level data from recent decades has questions about it due to the urban heat island. Does anyone think that Heathrow temperatures truly reflect London?
5. Atmospheric CO2 has gone up c. a third since 1950, see
http://woodfortrees.org/plot/esrl-co2/from:1900/to:2017 .
6. Global temperatures have increased but in a much less sustained fashion than CO2, see
http://woodfortrees.org/plot/uah5/from:1900/to:2017 .
7. Natural phenomena (e.g. the spikes on that graph which are the 1997-98 and 2014-16 El Nino events) are the biggest recent effects.
8. The late 20th century warming (late 70s to c. 1998) is almost identical to the early 20th century warming (mid 1900s to late 1930s), and the latter happened before there was a dramatic increase in atmospheric CO2.

My conclusion is that it is obvious that adding a significant amount of CO2 to the atmosphere is likely to have some effect on global temperatures. Some direct (by delaying heat loss to space) and some indirect (by increasing plant growth), and some of these may well act in opposite directions. What the overall impact will be no-one knows In the IPCC's First Assessment Report (1990) climate sensitivity (the change in global temperature for a doubling of CO2) was said to be most likely to be between 1.5 and 4.5 °C. Almost thirty years later that vitally important figure has not been nailed down any more accurately.

Reducing fossil fuel use (e.g. through more efficient appliances and insulation) has clear short-term benefits and seems obvious to me. Adding significant costs to fuel & taxpayer bills to subsidise unreliable wind & solar plants to possibly offset an unquantified possible future problem seems daft.

 

[JohnW2]

Meehl et al. (2004) took a different approach. Instead of projecting future surface temperature change, they used climate models to attempt to attribute past temperature changes in a method known as 'hindcasting' (as opposed to forecasting).

Fair enough - that's really just a word to describe modelling of the available historical data.

In their study, Meehl et al. show that natural forcings cannot account for the increase in global temperatures in the second half of the 20th century, and that models using both natural and anthropogenic forcings model the temperature change over the 20th century most accurately.

I'll look at the paper properly later, but at first glance, they appear to have only considered two possible non-anthropogenic factors ('forcings'), namely volcanic and solar. As I keep saying, the difficulty is that the climate changes may be in part due to any number of factors (not just anthropogenic, volcanic or solar), some of which may be unknown, poorly understood or for which we currently have no historical data to model.

A number of studies using a variety of different statistical and physical approaches have, like Meehl 2004, estimated the human and natural contributions to global warming. They universally find that humans are the dominant cause of the observed global warming over the past 150 years, 100 years, 50 years, 25 years, etc. In fact, many conclude that natural effects have actually been in the cooling direction in recent decades (Figure 2).

If I get a chance, I'll try to look at some of those as well. However, again, I find it hard to see how they could have become confident, let alone certain, that "humans are the dominant cause of the observed global warming" in the past when they may well not have considered (since they don't know about them) other factors which could well be contributory, if not major factors.

I still think that we are probably still far more ignorant about these matters than some seem to believe, or want to believe.

Kind Regards, John

 

[JohnW2]

However you only get 97% if you have Diane Abbot type arithmetic skills. ... I don't think that 75/10,257 or even 75/3,146 is anything like 97%. ... That totally leaves aside the fact that the second question is so vague as to be essentially meaningless. What is a 'significant contributing factor', 10%, 25%, 50%, 75%? .... Also, in 1900 at least 97% of experts would have said that the continents were not moving, and they would have been wrong.....

Quite so.

My conclusion is that it is obvious that adding a significant amount of CO2 to the atmosphere is likely to have some effect on global temperatures. Some direct (by delaying heat loss to space) and some indirect (by increasing plant growth), and some of these may well act in opposite directions. What the overall impact will be no-one knows .... Reducing fossil fuel use (e.g. through more efficient appliances and insulation) has clear short-term benefits and seems obvious to me.

That is very close to my view but, as you say, we just don't know, but can take steps which seems sensible and logical to address what appear to be fairly 'obvious' factors. Despite what some people seem to assume, I think that our ignorance is such that we cannot be certain that reducing "anthropogenic" factors to the level at which they were, say, pre-1900 would necessarily take global temperatures back to anything like the levels they were at at that time.

Kind Regards, John

 

[Doggit]

Stop spouting half truths and random theories.

It's called a discussion Mikeey, and until I spout it, I can't get it corrected. I have no problem being proved wrong, I just ask for a degree of politeness when you do it. Oh, and the total emmited by all volcanoes including the underwater ones, is reckoned to be nearer 0.645 Billion tonnes, but otherwise you're right.

But looking at some of the research, a comment someone made a year ago sprang to mind. If a gallon of petrol weighs about 7lbs, how can it produce 20lbs of CO2. Now it can produce a greater volume, but even my basic maths tell me you can't get more from less.

 

[mikeey84]

We have very little robust global data to work with.
The only close to global data is from satellites and that only goes back to the 1980s. Climate is normally defined as a 30 year average. So we have enough data to produce one reasonably reliable data point. Even that one data point has some caveats as some satellite instruments have gradually failed and satellite orbits have changed in ways that were not predicted which affected the way the results had to be interpreted.
2. Older data is very patchy. The oldest data set (Central England temperature) only goes back to 1659 or 1722 for the better data. In geological terms that is nothing and it only covers one part of England. Wider decent data (Europe, the British Empire, the US) only goes back to the 19th century.
3. Good ground level data is not available on a worldwide basis even today. Large chunks of Africa and Asia and both Polar regions are poorly covered.
4. Some of the ground level data from recent decades has questions about it due to the urban heat island. Does anyone think that Heathrow temperatures truly reflect London?

Independent studies using different software, different methods, and different data sets yield very similar results. The increase in temperatures since 1975 is a consistent feature of all reconstructions. This increase cannot be explained as an artifact of the adjustment process, the decrease in station numbers, or other non-climatological factors. Natural temperature measurements also confirm the general accuracy of the instrumental temperature record.

Fortunately, there is not much difference in the temperature trend between airport and non-airport stations.

Global temperatures have increased but in a much less sustained fashion than CO2, see

Natural phenomena (e.g. the spikes on that graph which are the 1997-98 and 2014-16 El Nino events) are the biggest recent effects

That carbon dioxide causes warming is well established by physics theory and decades of laboratory measurements. This is confirmed by satellite and surface measurements that observe an enhanced greenhouse effect at the wavelengths that carbon dioxide absorb energy. Given the strong causal link between CO2 and warming, what are we to make of periods where CO2 does not correlate with temperature? The most commonly cited example is the recent years since 2002. Over this 7 year period, global temperature has shown little to no trend while CO2 has risen. If CO2 causes warming, shouldn't temperature be rising steadily also?

However, this is a short period as far as climate trends are concerned. To understand recent years in the broader context of long term climate trends, one needs to look at the temperature record over several decades. By comparing carbon dioxide levels to temperature from 1964 to 2008, it becomes apparent that even during a long term warming trend, there are short periods of cooling.

 

[mikeey84]

humans are the dominant cause of the observed global warming" in the past when they may well not have considered (since they don't know about them) other factors which could well be contributory, if not major factors.

What sources of co2 or heat are you considering? Only 2 real sources of heat, the sun and geothermal activity. Both are considered in models I have seen.

As I stated, major sources of co2 are humans and volcanic activity, the latter being dwarfed by the former. Is there an "unknown unknown"? Its impossible to say, but there is little empirical evidence to back up the assertion that there is another cause of the massive increase in co2 concentrations and the increase in warming that has been seen

 

[mikeey84]

The 97% figure come from work done by by Doran & Zimmerman of the University of Illinois at Chicago.

There have been 7 major studies of consensus on ACC.

4 studies gave 97% consensus, 1 gave 100% and other 2 vary between 91 and 93%.

There is a very strong correlation between climate science expertise and consensus.

 

[flameport]

If a gallon of petrol weighs about 7lbs, how can it produce 20lbs of CO2. Now it can produce a greater volume, but even my basic maths tell me you can't get more from less.

The C is carbon from the fuel, the O2 is oxygen from the air.
It's not more from less, but that oxygen from the air is also used to create the end products.

 

[Doggit]

Interesting, I can see the reasoning now. Thanks for that

 

[JohnW2]

What sources of co2 or heat are you considering? Only 2 real sources of heat, the sun and geothermal activity. Both are considered in models I have seen.

It's not really the sources (of CO2 or heat) that I am talking about, but, rather the question of the activity of the natural CO2 regulatory mechanisms.

As you have said, I would hope that there is no argument about the fact that 'greenhouse gases' result in a 'greenhouse effect' and the fact that human activity has been pushing increasing amounts of greenhouse gases into the atmosphere.

As above, what I am talking about is the role which the natural CO2 regulatory mechanisms play. One has to remember that the (pretty small, only about 0.04% by volume) 'relatively constant' (despite this discussion!) amount of CO2 in the atmosphere is the result of the balance between large amounts going into the atmosphere (primarily from biological sources and released from the sea) and going out of the atmosphere (primarily by biological mechanisms and dissolution in the sea) - I believe a total annual 'turnover' of around 800 GT (800 billion tonnes) per year (in both directions).

As you have said, the 29 or so GT of 'anthropogenic' CO2 will have a small effect on the total 'input', but my point is that just a small change in either the biological or oceanic removal of CO2 could have a large effect on the 'balance', hence the amount of CO2 in the atmosphere, even if the 'input CO2' had not changed at all.

Is there an "unknown unknown"? Its impossible to say, but there is little empirical evidence to back up the assertion that there is another cause of the massive increase in co2 concentrations and the increase in warming that has been seen

As I've said, I don't think there is any dispute that increased CO2 (and other greenhouse gases) results in warming, so the only relevant possible 'unknown unknowns' relate to possible 'other' mechanisms for the atmospheric CO2 levels having risen as much as they have. As above, it would only take a very small decrease in the uptake of CO2 by biological organisms and/or the ocean, or a very small increase in CO2 release by those same things, to result in the atmospheric CO2 level rising much more than would be the case if the only change were due to input of 'anthropogenic' CO2. Although 'unknown unknowns' are obviously unknown, one can certainly speculate about various possible ways (some due to human activity - so, I suppose, also 'anthropogenic', but not due to the burning of fossil fuels) in which biological organisms and/or the oceans may have changed a little in their behaviour.

Kind Regards, John