A Matter of Time

[lucaspa]

lucaspa

 

I get the impression that you are creating an argument where none exists.

 

Interesting coming from someone who has 3 times made agreement look like argument.

 

1. I am not disputing that agricultural practices will or should change. However, I accept that it is going to happen.

 

The rest of us are not as sure that this is the "fact" that you think it is. The changes are based on a lot of human factors that are not required to conform to the reasonable or logical scientific position. I urge you to be more cautious about your assertions on the future.

 

They will be more productive per acre, due to increased efficiencies and better technology.

 

Again, there is an upper limit to productivity. The laws of physics and biology ensure that. You don't seem to consider that fact. We may not have reached the limits of technology in regards to food production, but there are such limits.

 

2. Population change. Sure, there are lots of uncertainties in the projections. This is called the error factor.

 

No, it's not called "the error factor". The error factor comes from inherent differences in different measurements of the same thing. Take a ruler and measure a line 10 times, and you get 10 different measurements. The difference in those measurements is the error factor. Look below before replying, because that is NOT what is happening here.

 

The projection that the world population will reach 9 billion and then start to drop, is an average of many calculations.

 

No, it's not. Read the article. It is a single calculation based on a single set of assumptions. It is NOT "the 'most probable' figure". You are thinking above about the difference in several measurements and making a bell shaped curve. You think 9 billion is the middle of the curve and 11 billion is off to the right.

 

That's not what is happening. Instead, the team takes different sets of assumptions about fertility, death rates, migration(when looking at regions), and then does a calculation extrapolating propulation.

 

You didn't even read the quote I gave, SkepticLance! It's right there: "To project population until 2050, the United Nations Population Division applies assumptions regarding future trends in fertility, mortality, and migration. Because future trends cannot be known with certainty, a number of projection variants are produced." Pay attention! Look at the DATA, stop ignoring it and saying something complete contrary to what is being done. What you are doing is really poor science, so poor it is not science at all.

 

However, the probability of a maximum less than 9 billion is about the same as one more than. The probability of a maximum above, say, 11 billion is very low.

 

Now do you see how wrong you are? NONE of the projections are "more probable" than any other. Not based on the number. The only way one can be more probable is that the assumptions are more probable. And this is not the case. "Medium" doesn't mean "more probable". It means just that: between the lower and higher assumptions. That's all. But there is no way to tell which of the assumptions are more probable.

 

If anything, the more probable assumption is that birth rates are going to stay the same! That assumption involves no change in the overall behavior of humans. And, of course, that assumption gives you the highest population numbers.

[lucaspa]

These, SkepticLance, were all the averages of many calculations assuming different scenarios.

 

Sorry, but you missed it too. These are NOT "averages of many calculations". They are ONE calculation based on ONE scenario. We have 4 projections because there are 4 scenarios. There is no averaging being done here. We have 4 separate calculations.

 

There is no guarantee that the peak will be 9 billion by 2050 because these calculations are based on the average fertility rate per year.

 

It's worse than that. The "middle case" that gave the 9 billion is based on the assumption that the fertility rate will change in the 45 years from 2005 to 2050. It's not an "average fertility rate" -- that implies measurement -- but instead picks a fertility rate for each year from 2005 to 2050. Since those years are in the future, there is no measurement. It's an assumption. As you noted, reality doesn't have to match the assumption.

 

But SkepticLance is "assuming" that the assumption is correct when he states that population will stablize as tho it were a fact. You can't have a "fact" based on the assumption of an assumption. Facts are observations.

[MolotovCocktail]

Sorry, but you missed it too. These are NOT "averages of many calculations". They are ONE calculation based on ONE scenario. We have 4 projections because there are 4 scenarios. There is no averaging being done here. We have 4 separate calculations.

 

Sorry, misunderstanding on my part.

 

 

It's worse than that. The "middle case" that gave the 9 billion is based on the assumption that the fertility rate will change in the 45 years from 2005 to 2050. It's not an "average fertility rate" -- that implies measurement -- but instead picks a fertility rate for each year from 2005 to 2050. Since those years are in the future, there is no measurement. It's an assumption. As you noted, reality doesn't have to match the assumption.

 

So, pretty much, what you are saying is that the fertility rates are educated guesses at best (which basically means we have no idea how populations rates will be in the future). Which means that there could be an event in the future in which fertility rates could spike up. Yikes!

 

But SkepticLance is "assuming" that the assumption is correct when he

states that population will stablize as tho it were a fact. You can't have a "fact" based on the assumption of an assumption. Facts are observations.

 

This is very true.

[lucaspa]

So, pretty much, what you are saying is that the fertility rates are educated guesses at best (which basically means we have no idea how populations rates will be in the future). Which means that there could be an event in the future in which fertility rates could spike up. Yikes!

 

Yep. Which is why there are the 4 scenarios. Based on different educated guesses on what the fertility rate (and mortality rate!) is going to be in the future. Don't forget mortality rate. Say we develop cheap tissue engineering and find a cure for cancer. What happens to the mortality rate? It plummets. We have a lot more total people because they simply aren't dying anymore, so the population projections are hosed.

 

This would be one case where SkepticLance's (nonskeptical) optimism in technology would really screw up his optimism. Ironic, isn't it?

[SkepticLance]

I must really have ruffled lucaspa's feathers. We had no argument, but lucaspa appears intent of creating one.

 

Let me just say this. When attempting to predict the future, it is easy to go wrong. However, one of the most reliable systems is to take existing long term trends and project them onwards. Not perfect, but more reliable than any other system.

 

For population trends, the United Nations has taken a long term trend - the reduction in average fertility world wide - and projected that into the future. That trend leads to a prediction of a peak population of 9 billion. Whatever you say, that is a figure of greater probability than 8 billion or 10 billion etc. Sure, it might be wrong, which is why we talk of probability, not certainty.

 

My statement about agricultural practices is also based on the same general principle. The long term trend is for continuing change in how farmers produce their crops, and for continuing increase in productivity per acre. It is a very reliable basis for predicting that trend to continue into the future. Sure, it is not certain. Perhaps an asteroid will fall on our heads. But it is probable.

 

And biological productivity has limits, sure. But we are still a long way from those limits.

[lucaspa]

Let me just say this. When attempting to predict the future, it is easy to go wrong. However, one of the most reliable systems is to take existing long term trends and project them onwards. Not perfect, but more reliable than any other system.

 

But you didn't state this as "more reliable", did you? You stated it as FACT. You said "It is now expected that the world population will not exceed 9 billion."

 

That isn't what is "expected". That is ONE possible scenario and is not even the most expected. It is the MIDDLE scenario of the "high, middle, and low" possibilities.

 

For population trends, the United Nations has taken a long term trend - the reduction in average fertility world wide - and projected that into the future. That trend leads to a prediction of a peak population of 9 billion. Whatever you say, that is a figure of greater probability than 8 billion or 10 billion etc.

 

It has taken THREE versions of "the" alledged trend. But there is no way to say that this has "greater probability". The site specifically says it is NOT talking probability, but simply cases. One reason for this is that birth rate may already be as low as it is going to go; the middle case supposes a birth rate less than replacement. That may not be likely. You continue to misrepresent the data and I, quite rightly, object to that. First you have to get the science right and you haven't done that.

 

Now, if we extrapolate contemporary birthrates, then we don't get stabilization at all.

 

The long term trend is for continuing change in how farmers produce their crops, and for continuing increase in productivity per acre. It is a very reliable basis for predicting that trend to continue into the future.

 

But here there is an upper limit on productivity per acre. The trend can't continue forever. As I said, physics and biology set an upper limit to the yield per acre. So unless population stabilizes there is going to inevitably be a situation where there are more people than can be fed.

 

And biological productivity has limits, sure. But we are still a long way from those limits.

 

Data, please? Checking up on your "data" so far shows that you haven't gotten the science correct. So your track record is poor and not to be trusted. We need the data behind this assertion.

[SkepticLance]

lucaspa said :

 

You stated it as FACT. You said "It is now expected that the world population will not exceed 9 billion."

 

I hate to say this, lucaspa, but you are getting ridiculously picky. I have said several times that nothing is fixed, and there is the possibility of final population being more or less than 9 billion.

 

I spoke of probability, and you say it is scenarios. We are arguing semantics. Who cares what word is used to describe it. Let's say that 9 billion is the 'central' scenario and stop arguing silly meaningless points.

 

As I pointed out, the predictions are based on the long term trend for fertility dropping. That is a trend seen all over the world, including 'high fertility' third world countries. From memory, the average for the third world was about 5.5 per woman about 50 years ago, and is now down to 2.5. For first world countries, it is below 2 in most cases.

 

There are still countries with fertilities of well above 2.5, but the average is falling. Not only that, but repeated surveys have shown that women the world over do NOT want large families. They end up with too many pregnancies due to lack of access to birth control. However, birth control access is increasing, and that is resulting in falling fertility. If you are worried about population growth, then push for more aid in supplying birth control to third world countries, and the result will be an accelerated drop in fertility.

 

However, this drop is happening anyway.

 

These are facts, and I do not see why you feel the need to argue.

[foodchain]

I hate to point this out but I think its a bit more difficult to get some absolute mathematical reality of human populations then it would be with another physical system or entity such as a comets path for instance. If we could predict with certainty human behavior, then well I think war would never really occur to be honest. That aside, I don’t know of any real way to slow down the growth of our species. I mean china has some laws around such that I know of, hated by most anybody I talk to, save they wont go into detail on how the world would support, or how china for that matter would support a 3x population boom in the next decade, perhaps the U.S will share money and power with them, LoL!.

 

Anyways, I think ultimately what will occur is rather severe damage will have to take place in the environment that begins to hurt people, from business, to individual, to nations. I think at that point humans per say might begin to recognize the need for say understanding and adaptation, though such is only a prediction. I think current trends though would suggest such a future, the reason being no real pressure or stress yet exists to select for something different then the current mode of operation really. Its typically just noise associate with tree huggers or what not.

[MolotovCocktail]

Anyways, I think ultimately what will occur is rather severe damage will have to take place in the environment that begins to hurt people, from business, to individual, to nations. I think at that point humans per say might begin to recognize the need for say understanding and adaptation, though such is only a prediction. I think current trends though would suggest such a future, the reason being no real pressure or stress yet exists to select for something different then the current mode of operation really. Its typically just noise associate with tree huggers or what not.

 

Can't say I agree with you here. I happen to be a little bit of an optimist. For example, we did not have to wage nuclear war to know to avoid doing so.

 

Based on that, I don't think we will let things get that bad, well at least in other parts of the world that is .

[SkepticLance]

Why is it that so many people prefer pessimism and predictions of disaster to reality?

 

Globally, fertility is dropping. This is not some optimistic speculation. It is fact. In the first world, human reproductive rates have already fallen well below replacement. In many countries, there is now real alarm about the low birth rate. In Japan, the government is trying to figure out how to get women to have more than one child - and failing badly! Ditto for Italy and a number of other places.

 

The United States population is growing only because of very substantial immigration - a million people per year.

 

In third world countries, populations are still growing, but at an increasingly reducing rate. As I said earlier - at current fertility level of 2.5 per woman, as opposed to 5.5 some 50 years ago. And the fertility rate is still dropping.

 

It is because of these long term trends that the United Nations can predict future populations. A peak of 9 billion plus or minus a bit by 2050, and then a slow reduction in global population due to the fact that all nations will have fertility rates less than 2 per woman.

 

Overpopulation disaster is not coming. With a little effort we can cope with 9 billion, and things will get easier after that as economies grow and numbers drop.

[lucaspa]

I spoke of probability, and you say it is scenarios. We are arguing semantics.

 

No, we are not. Probability is a very specific statistical term you use when you can calculate how "probable" one value is among many values. This is based on a population of values and we calculate how many times that value occurs compared to the total number of times ALL values occur. Thus, looking at a population of human individuals and making the bell-shaped curve, we can say there is a 95% probability that an individual will be between value x and value y. Out of 100 individuals picked at random, 95 will be between x and y.

 

Scenarios occur when you arbitrarily pick parameters and see what happens. There is no "probability" that a particular scenario is correct. And certainly not in this particular case, where each projection of world population represents ONE value obtained.

 

As I pointed out, the predictions are based on the long term trend for fertility dropping.

 

No, not all the predictions are based on that. You have, in fact, 3 scenarios based on decline in birth rates and constant mortality rates. One of them gives a world population greater than 9 billion and not stable. Of course, the scenario using today's birth rates gives you a VERY high world population.

 

Notice that you are forgetting the other half of the assumptions: mortality rates as they are today. BUT, those are also declining. People are living longer, yes, even in developing nations. Therefore you cannot take the projections as infallible.

 

These are facts, and I do not see why you feel the need to argue.

 

Again, you can't distinguish between facts and hypotheses. Nor did you provide data for declining birth rates. Once again you are presenting a "fact" but without the supporting data. On another thread you say you don't accept "authority" but want to see data, but you present yourself as authority without the data.

 

I asked you to present data in my last post to back up a claim. You didn't. I asked for data that we were a long way from the limits of what you called "biological productivity". Where is the data?

[lucaspa]

It is because of these long term trends that the United Nations can predict future populations. A peak of 9 billion plus or minus a bit by 2050, and then a slow reduction in global population due to the fact that all nations will have fertility rates less than 2 per woman.

 

Again, you misrepresent what the United Nations data said! All the data presented said was that population was going to be 9 billion with a slow growth rate. NOTHING about a peak and then "slow reduction"

 

Now, you also said that population in developing nations would come with access to birth control. Can you be assured that will happen?

 

As to "preferring pessimism", it's obvious you aren't a scientist. Every scientist knows Murphy's Law: whatever can go wrong, will go wrong.

 

It's not that we "prefer pessimism", but that we have been taught as scientists to avoid overinterpreting the data and drawing (optimistic) conclusions not supported by the data.

 

There's also the other saying: optimists have more fun, but pessimists are right more often.

[SkepticLance]

lucaspa said :

 

As to "preferring pessimism", it's obvious you aren't a scientist. Every scientist knows Murphy's Law: whatever can go wrong, will go wrong.

 

Wrong. It is engineers who so revere Murphy's Law.

 

Scientists revere objective truth. Murphy's Law is a specific principle based on an exaggeration - therefore not objective truth. For a scientist, only the actual data will do - not an exaggerated data base.

[Cap'n Refsmmat]

That's what he said. Scientists try to avoid exaggerating the data.

[SkepticLance]

lucaspa said :

 

Now, you also said that population in developing nations would come with access to birth control. Can you be assured that will happen?

 

Of course not. All I can say is that a number of surveys of third world countries have shown that women in general do not actually want to be turned into child bearing machines. They would like to have access to birth control, and limit their families to 2 or 3 children. Whether this actually happens depends on many factors, including various cultural factors.

 

However, average fertility in third world nations has been dropping for 50 years, as stated before. It makes sense that if those women are given access to birth control, they will use it.