More people, greater prosperity, and more nature are all good things. But, given the finite resources of the Earth there is always a trade-off between the three.
How much of the Earth's resources are currently allocated to each one? How do you weigh the trade-offs between the three? Are they at an ideal balance, or should more resources be allocated to one of them? How can technology change the amount of resources available and what needs to happen to make things look optimally in 2050?
Lets take a look at these questions.
Determining how the Earth's resources are allocated between people, prosperity and nature requires a metric to measure the consumption of each. One such metric is Net Primary Productivity which quantifies the amount of biomass generated each year by plants. It is measured in terms of grams of carbon (gC). The total amount of NPP limits the number of people on the planet, their level of prosperity and the population sizes of species in nature.
Prosperity here is defined as NPP consumption above that required for sustenance. Greater NPP consumption allows for more food and meat to eat, more cotton for clothing, more biofuels for warmth, cooking and transportation, and more wood for housing, furniture and paper (see caveats about prosperity derived from non NPP sources such as fossil fuels).
2000 Allocation
59.22 PgC of NPP was generated on land (excluding oceans, see caveats) in 2000 (source 1). Of that humans appropriated 9.32 PgC (15.7%), or 1,553 kgC of NPP for each of the 6 billion people alive (source 1). A person requires 182.5 kgC of NPP a year for survival (based on 2,000 calories a day). This means that 12% of human utilization of NPP was used for basic survival and the remaining 88% (1,371 kgC) allowed for additional prosperity. Overall, of the 59.22 PgC of NPP created in 2000, 1.8% (1.1 PgC) was used to give life to 6 billion people, 13.9% (8.23 PgC) was used for additional prosperity and 84.3% (49.9 PgC) was left for nature.
There was a larger variance in the kgC of NPP consumption per capita by region (source 2).
Trade-offs
Economists are fond of saying there is no such thing as a free lunch, meaning that everything has a cost and there are always trade-offs. It is particularly apt in this discussion, as the NPP from the food you eat at a meal could also be used to allow other people to live or for additional nature. To determine the optimal balance between people, prosperity and nature we need to look at the implications of the trade-offs.
People vs Prosperity
Is it better to have fewer people with greater prosperity or more people with less? Is it better to have as many people as possible, or fewer people with more food, meat, clothing and housing available for each? This is the classic quality vs. quantity debate.
If the total human usage of NPP stayed at 9.32PgC, but everyone consumed at the Oceania level of 8,750 kgC of NPP per person, the Earth could sustain just under 1 billion people. At the North African level of 797 kgC, 11.7 billion people. At the level of bare sustenance of 183 kgC, 50 billion people. Which is better?
One way to determine the optimal balance is to measure how much benefit people get from greater prosperity in terms of increased happiness (or well-being) and then find the point where the marginal increase in happiness from additional NPP consumption would be better allocated to allow more people to live.
Data on life satisfaction (or happiness) and NPP consumption by region can be roughly modeled by the equation Happiness = 2*Log(kgC of NPP) (excluding the 3 unhappiest regions which have higher NPP consumption than expected). A graph of this can be seen at right. One implication of this equation is that the more prosperous you are, the less benefit in happiness you get from additional consumption (or in economic speak, decreasing returns to happiness from additional NPP consumption).
Using the equation we see that a person close to starvation (100 kgC of NPP consumption) gets a much larger increase in happiness from an additional 2,000 kgC of NPP (2.6 points of happiness, from 4 to 6.6) than an extremely prosperous person (6,000 kgC of NPP) gets from that same 2,000 kgC (.2 points of happiness, from 7.6 to 7.8).
How much better does life have to be to justify using additional resources? This will always be a subjective decision, but if you set a level of increase of happiness required for additional NPP consumption (seen graphically as the slope of the line or numerically as the derivative: y=2/((kgC of NPP)*ln(10)) ), then you can solve for an optimal level of NPP consumption. If you believe that an increase of 1 point of happiness can be justified by up to 2,000 kgC of additional consumption, then the optimal level of consumption can be found by the equation 1/2000 = 2/((kgC of NPP) * ln(10)), NPP= 1,737 kgC. This would be a level of prosperity just below Western Europe. Keeping the total human appropriation of NPP constant at 9.32 PgC this level of consumption leads to a population of 5.4 billion people with an average happiness level of 6.5.
Another implication of this model is that total well-being is higher the more equal consumption is. Two people consuming at 2,000 kgC gives more combined happiness (6.6*2=13.2) than 1 person at 500 and another at 3,500 (5.4+7.1=12.5).
A second way to find the balance is to take into account that people can increase their happiness by giving away resources. The optimal level of prosperity is then the point where people get more marginal well-being from giving away additional NPP to allow others to live than they would from consuming it themselves. This can be thought of as the Schindler trade-off, as it exemplified by Oskar Schindler who saved the lives of 1,200 Jews by giving away his resources rather than consuming them himself. This behavior can be seen in people who reduce their own consumption and instead support non-profits like Feed the Children that allow additional people to live. The Schindler trade-off also has the interesting implication that if you start with 2,000 kgC of NPP and give 500 of it away, you have greater well-being than if you just started with 1,500 kgC and consumed it all, even though in both cases consumption is the same.
One final point to take into account when determining the balance between people and prosperity is that more people leads to greater richness in life for all. More people means more artists to create more entertainment options, more scientists to generate more medical breakthroughs, more manufacturers to build more types of products, and more researches to develop more new technologies. The well-being of all is increased with more people being alive.
People vs. Nature
What is the right balance between the human population and the amount of nature? For the last 50,000 years the balance has steadily been shifting in favor of humans, with the human population growing from a few thousand to 6 billion and the amount of nature decreasing correspondingly. Has that been a good thing? Would it be better if there were even more humans alive, or fewer with more nature?
One place we can look to try and find an optimal balance is the Americas where the balance between humans and nature has shifted back and forth over time rather than just shifting towards humans.
Jared Diamond writes "About 15,000 years ago, the American West looked much as Africa's Serengeti Plains do today, with herds of elephants and horses pursued by lions and cheetahs, and joined by members of such exotic species as camels and giant sloths." Humans first appeared in the Americas 13,000 years ago coming over the Bering Strait. Within a few thousand years all of those species went extinct. The amount of nature continued to decrease as the population of humans grew to a size of around 100 million in 1491.
The balance then shifted back towards nature starting in 1492, when Columbus brought with him small pox and other diseases that reduced the Native American population to just 5 million in 1600. Nature flourished, with the passenger pigeon going from being a rare species to being so large that a flock could form a single cloud that took 3 days to pass overhead. The population of buffalo also exploded as did the size and density of forests.
As Europeans started immigrating the balance shifted back to humans, and the population of the Americas rebounded to its earlier level and then increased even further to 835 million in 2000. As expected, the amount of nature decreased, with the passenger pigeon going from a population of 5 billion to extinction, buffalo being pushed to the verge of extinction and forests sizes decreasing.
Because we feel losses stronger than gains of equal magnitude, it is hard not to think that it was a bad thing when the lions and cheetahs went extinct, or when diseases ravaged the population of native Americans, or when the passenger pigeon went extinct. But, it is much harder to weight the benefit on the other side of the scale and determine at what point the optimal balance between people and nature was obtained.
One way to determine the balance would be to allocate resources to all species based on favorable traits such as intelligence, the complexity of their societies, the diversity of how they live and their overall uniqueness. The more they enrich the planet, the more resources they should get. By that standard humans rate very high as a species and justify a large share of NPP.
Another way to set the balance would be to allocate land to humans and nature based on who can use in more productively. Some ecosystems humans can utilize very well, such as grasslands which can easily be turned into farms, while others, such as swamps, not so much. It has been written that the Amazon rainforest is a "wet desert" because the soil is poor and the nutrients have been washed out. Better to leave that land to nature which has build a productive ecosystem out of it, then convert it to substandard farm land. Along with this, wilderness areas should be left large enough to protect against ecosystem collapses that would cause NPP productivity drops for the region.
For an example of how to apply these principles, lets look at sperm whales and humans. There are 350,000 sperm whales alive today that take 80-100 million metric tons of krill and other sea life out of the ocean each year. That is a greater tonnage than humans take out of the ocean. If reducing the population of sperm whales by 100,000 freed up enough resources to allow 1 million more people to live, would this be a worthwhile trade-off? From the first principle, the 1 million people are likely to enrich the planet more assuming that 250,000 sperm whales is enough to allow for a stable population. From the second principle, we would determine who would utilize the NPP better. Whales do a good job to gathering and digesting krill, while humans could use the krill to increase the amount of fish in fish farms. Harder to judge which one would use it better, but I would lean toward the whales. Putting these two together and I would go with a lower population of whales and more humans.
Prosperity vs. Nature
What is the right balance balance between human prosperity and the amount of nature? Should the amount of nature be reduced in order to allow for greater prosperity: more meat or more nature?
One way to determine the balance is to allocate land to nature or greater prosperity based on which increases well-being more. Nature leads to greater well-being in many ways. First, more nature makes it more accessible and allows for more people to participate in enjoyable activities such as walks in public parks. Second, more nature allows for greater vacation options in terms of beaches to visit, national parks to camp in, or marine parks to scuba dive in. Third, more nature allows for better entertainment and education options through increased subject material for nature documentaries.
The higher a nation's level of consumption, the more likely that additional nature would lead to greater well-being (due to the decreasing returns to NPP consumption). At some point, a nation would gain more benefit from having 1 million wild buffalo than an extra million cattle for hamburgers or a larger population of wild hogs than the ability to eat more bacon. At the national level, you could take a look at the amount of well-being that citizens derive from the current level of nature and then check if decreasing the amount of nature by 10% would give people more well-being from the additional prosperity that land allows for. Or you could go in the opposite direction and see if increasing the amount of land to nature by 10% would give people more well-being.
Another way to determine the balance is to find the point where people get greater well-being from giving away their NPP to nature than they would get by consuming it themselves (same concept as the Schindler trade-off above). Those that contribute to environmental causes or choose to be vegetarians for environmental reasons demonstrate this principle.
The 10,000 kgC Question
If the 59.22 PgC of NPP generated in 2000 was evenly distributed between the 6 billion people alive, there would be ~10,000 kgC per person. If you could choose how your portion was allocated, how much would you consume for your own prosperity, how much would you give to allow additional people to live and how much would you give for nature? While explicitly setting these levels and looking at the trade-offs is challenging and difficult to do, to not do so allows them to be set implicitly, to the detriment of everyone.
I would choose to consume 1,750 kgC allowing me a lifestyle similar to the average Western European. Beyond that, I would get greater well-being from giving the rest away than I would consuming it. Of the remaining 8,250 kgC, I would set aside 7,700 kgC for nature and 1,180 kgC to allow another 2/3 of an additional person to live at a similar level of prosperity as me. Nature's share would be large enough to protect biodiversity hotspots and other national parks that would give me well-being by allowing me to vacation there and watch them in nature documentaries. The increase in the number of humans on the planet would also make my well-being greater by increasing the richness of life.
From a global perspective, if everyone allocated their NPP like me, there would be a world population of 10 billion (an increase of 66%), 42.4 PgC of nature (a reduction of 15% leaving nature with 70% of all NPP), and an average level of prosperity of 1,750 kgC (an increase of 13%). The level of prosperity would be close to the point where 1 additional point of happiness would require another 2,000 kgC of consumption. I think this is a good level in the trade-off between more people and greater prosperity. While the amount of nature would be decreased, I believe this is justified by the greater richness of the human species compared to other species. Humans should convert all land to farms where they could generate more NPP than would be generated leaving it to nature, such as grasslands in Russia and Africa.
Overall, I think this would be the optimal allocation of resources between people, prosperity and nature based on the various trade-offs outlined above.
Technology
Technology in the form of greater productivity and greater efficiency allows for greater total NPP allowing for more people, greater prosperity or more nature without trade-offs.
Productivity - This is accomplished by increasing the amount of NPP generated per acre of land. There is great potential for increasing productivity of land as only .2% of all solar energy reaching the Earth is captured by plants via photosynthesis (and only 5% of the sunlight that actually hits a leaf). If all the farm land in the US was replaced with solar panels, they would collect 480 times more energy than the calories in the food they produce. Capturing just a fraction of the 98.8% of sunlight that isn't converted into biomass could greatly increase the amount of NPP on the planet and allow for more people, greater prosperity or additional nature.
Examples of how this could be accomplished include: increased mechanization, irrigation, and fertilization, smarter irrigation (perhaps using laser beams), vertical farming, genetic modification of crops, terra preta, better forest management, reclaiming deserts for agriculture and fertilizing the ocean.
Efficiency - This is accomplished by decreasing the amount of natural resources needed to make goods. Greater efficiency allows the same level of prosperity using less NPP. Examples include: decreasing the amount of waste from farming, increasing efficiency of turning grains into meat, reducing the amount of food thrown out, recycling paper, wearing vintage clothing, and turning bio-waste into biofuels.
A second type of efficiency is increasing the amount of well-being derived from resources used. This can be accomplished by finding ways to get the same benefit with fewer resources such as eating fish that are lower on the food chain which use less NPP for the same amount of food. It can also be accomplished by increasing consumption of goods that give the greatest well-being return on resources used and decreasing those that don't. Activities that increase well-being with little use of natural resources should be increased such as gratitude journals, spending time with family and friends and meditation. Consumption of goods that do little to raise well-being should be decreased such as large houses, long commutes and excessive meat and food consumption that leads to obesity and lowered health.
It should also be noted that while technology can enlarge the pie, mismanagement can also shrink it. In 2000, 6.29 PgC of potential NPP was lost due to human alterations of the land and 1.14 PgC (12% of human consumption) was lost to human induced forest fires (source 1).
2050 Possible Scenarios
How could things look in 2050?
Total NPP could be increased by 10% to 65.5 PgC by doubling the productivity of the 15.2 mil km2 of cropland from 397 gC/m2 to 794 gC/m2. While this sounds large, it is just an increase in productivity of 1.4% a year for 50 years. Doubling the productivity of cropland is feasible given that the US currently produces 9,482 kg/ha/yr of corn almost double the world average of 4,970 kg/ha/yr (FAO 2007) and much less than the 20,000 kg/ha/yr (329 bushels/acre) that was grown on one farm in Missouri. Monsanto has plans to double corn, cotton and soy bean crop yields by 2030 while cutting water, land and energy needs 30 percent. While 794 gC/m2 is greater than the productivity of this land before human alteration (611 gC/m2), it is possible to exceed the natural productivity of land due to irrigation and fertilization. Increasing NPP by 10% would also get back almost exactly the 6.29 PgC of lost productivity due to human induced alterations of land (Source 1).
At left are 9 scenarios (click on the image for a larger version) of how this 10% increase in NPP could be allocated between more people, greater prosperity or additional nature. Going from left to right the number of people is held constant, and going up and down the amount of NPP for nature is held constant.
4 scenarios are of particular interest:
1) All gains from technology go to nature. This is seen in the upper left entry, an increase of 12% to 56 PgC for nature.
2) All gains go to greater prosperity. This is seen in the upper right entry, an increases of 66% to 2,580 kgC/capita.
3) All gains go to greater population. This is seen in the bottom right entry, an increase of 66% to 10 billion people.
4) Gains get split evenly between nature, prosperity and people. This is seen in the center entry with an increase of 20% for people and prosperity to 7.2 billion people and 1,870 kgC/capita and a 4% increase in NPP for nature to 52 PgC.
Those four scenarios all assume no losers, that the amount of people, prosperity and nature all increase. It is also possible for greater increases if there were also losers but that would require trade-offs as described above.
Conclusion
In 2000 there were 6 billion people consuming an average of 1,550 kgC of NPP apiece and 50 PgC was left for nature. What would be the optimal levels for 2050 and what needs to happen to get there?
I would choose to allocate 70% of NPP to nature (45.85 PgC), and 30% for humans (19.65 PgC). Just as technological productivity increases could feasibly go up 10%, I believe that efficiency could reduce NPP needs by 10%. The 1,750 kgC of consumption that I previously stated to be an optimal level in 2000 could be accomplished with just 1,575 kgC in 2050. This level of consumption per person would allow for a population of 12.5 billion. From 2000 levels this would be a 8% decrease in nature, a 2% increase in NPP consumption per person and a 108% increase in population.
As discussed above, I think that humans are justified using a bit more NPP compared to nature due to our richness as a species and our ability to to use certain land more productivity than nature. This level of prosperity is such that it would require a large increase in consumption to significantly increase well-being. Better that those resources allow other humans to live.
In order to get to that ideal level in 2050, individuals will need to increase the efficiency of their consumption, companies will need to invest in R&D to increase productivity and efficiency, and governments will fund technological improvements and protect nature.
Further Research
1) How does kgC of NPP translate into real products? What does shifting from 1,000 kgC to 2,000 kgC mean in terms of consumption of products such as cotton, paper and wood products, biofuels, flowers, or rubber?
What does the average North African, North American or Oceania consumption look like in terms of real products or diet?
2) What would a diet that lead to optimal health look like? How many calories would come from grains, fruits, vegetables, meat and other animal products? How many additional calories would be required for exercise?
How much kgC of NPP would that translate to? A quick calculation of going from a minimal diet of 2,000 calories of corn to one of 3,000 calories with 20% of that from meat (assuming meat takes 5 times as much NPP per calorie) would take NPP from 182.5 kgC to 500 kgC (an increase of 270%). But, it would be nice to have a more refined version of this calculation.
Assumptions/Caveats
1) This analysis uses NPP to compare the allocation between people, prosperity and nature. This comparison could also be done using other metrics such as amount of land used, amount of energy used, amount of water used or ecological footprint. These other metrics might give a different conclusion as to the overall allocation.
This analysis ignores consumption of non-NPP resources such as fossil fuels, minerals and metals which lead to greater prosperity. On the one hand this doesn't make sense, as consumption of these non-NPP goods leads to greater prosperity and comparing well-being levels between Africa which uses biofuels for cooking and America which uses fossil fuels for the same function is not really fair. 2,000 kgC and 500 gallons of gasoline a year is different from 2,000 kgC and 0 gallons. On the other hand this makes sense as using NPP substitutes, such as fossil fuels or wind power instead of biofuels, allows more NPP for nature. Britain quit cutting down forests when they shifted to coal. If the use of fossil fuels leads to global warming which reduces (or possibly increases) NPP then this usage will be reflected in the results. Ultimately the amount of life on Earth is determined by NPP and the more we can shift to non-NPP consumption for prosperity, the more we allow additional people and nature to exist.
2) This analysis just looks at land and doesn't take into account the oceans. Wikipedia puts oceanic production of NPP at 48 PgC a year or 46% of total global production. I am not sure what % humans appropriate of this or how it would change the analysis.
3) This analysis doesn't take into account biodiversity. See my post on Economic vs. Ecological Statistics for more thoughts on that subject.
4) Source 1 states there are 2.46 PgC of backflows to nature. These are ignored in this analysis. They could be considered nature which would increase the amount of NPP of nature.
5) The losses due to human induced alteration in source 1 are not counted in human usage. This analysis is looking at how much NPP each category uses of actual NPP rather than potential NPP. If they were, then the appropriation to humans would be higher.
Sources
1) Quantifying and mapping the human appropriation of net primary production in earth’s terrestrial ecosystems
2) Global patterns of socioeconomic biomass flows in the year 2000: A comprehensive assessment of supply, consumption and constraints
3) A comprehensive global 5 min resolution land-use data set for the year 2000 consistent with national census data
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