Friday, December 28, 2007

Options Revisited

If the world’s population stabilizes at a constant value when the amount of available resources ceases to change (all consumed resources are renewable), my theoretical model of population and consumption projects that by 2278 the world’s population will be only twice the present population of the United States, and the per capita consumption will be practically equal to that of the United States today. Ideality (quality of life) would grow from 65 to 78. The world’s present population could live on 1/3 of its current per capita consumption (1/11 of that of the U.S.) if we reduced consumption immediately; and ideality would drop to 54. In both of these cases, business as usual and sustainability, the population would not crash, but we would be making a tradeoff between quantity and quality of life.

We could postpone the population decline by increasing our total available resources expanding into space until we reached the maximum speed attainable, but we would risk true population crash as per capita consumption was inevitably forced below what people needed for survival. If our per capita consumption continued rising at its current rate, and if we could travel at the speed of light (a physical impossibility), the population would crash in little more than about 3,000 years.

Monday, December 24, 2007

A Better Fit

If per capita consumption is modeled linearly over time, rather than exponentially as I was doing it, there is a better fit to the footprint and population data in my theoretical model. The results are similar to what I found earlier.

With business as usual, the world’s population peaks near 8.1 billion people by 2049, then drops to a minimum of 590 million by 2280. It then may grow until the minimum per capita consumption is reached, with 51 billion people in 2621 before crashing abruptly. The sum of the Ideal World indices from 2000 (IWIsum) is less than 700.

If we stop population growth and cut per capita consumption by 0.2 hectare per year until we reach 0.89 hectare, there will be some population loss before the population levels out at about 6.4 billion people with an ideality of 54 percent.

The ultimate best case growth, with a maximum speed of half the speed of light allowing resource growth at 5.9 percent per year, would last until 4356 before the per capita consumption dropped below a minimum of 0.1 hectare (with an IWIsum of 6E+21, or 6 with 21 zeros).At that rate, we would need to consume a mass equivalent to the Earth in about 900 years, when the IWIsum would be 9 billion.

Sunday, December 23, 2007

Increasing Resources

One fundamental decision will govern the future of humanity. We can either choose to live within our available resources, or we can try to increase the amount of resources.

To live within our available resources, we will need to do two things simultaneously: Stop population growth, and decrease our per capita consumption at a rate no less than 0.5 percent per year to 20 percent of its current value (by 2331). The population would level off without falling, and ideality would level off at 50 percent. If we could continue growing capacity (renewable resources) by 0.5 percent per year to a maximum of six billion hectares, then the target per capita consumption would be 30 percent of the current amount, reached by 2304.

If we choose to grow our resources, to maximize population as long as possible we will need to maintain a resource growth rate of at least 5.1 percent. Assume that by 2385 we can reach resources at the speed of an Apollo spacecraft on its way to the Moon and one global hectare of consumption is equivalent to a mass of 330 pounds; then our population could grow to a maximum of 21 trillion by 2440 and then plummet to zero by 2478. We could last until at least 2663 with a population of about three quadrillion people if we focused on consuming the entire mass of the Earth, but we would need to consume the entire Solar System’s (non-stellar) mass by 2855 to continue, which would require our consumption radius to be increasing at several thousand times lunar flight speed.

The sum of the Ideal World Index from 2000, to one significant digit, is 400 for business as usual; at least 3,000 for constant population; and 300,000 for growing resources (60 million if we consume the Earth and 3 billion if we consume the Solar System while continuing to increase resources).

Ideal World Index

I modified my theoretical model of consumption and population, introduced in the last post, to include exponential growth in the amount of resources available. I also accounted for the restriction of that growth after a maximum speed is reached (assuming a constant density of mass in an expanding sphere, and a constant mass per global hectare of consumption). In addition, I set adjustable minimum and maximum values for per capita consumption, and added a logarithmic curve fit of ideality (the average of lifespan and happiness) as a function of per capita footprint. While resources are increasing faster than they are being consumed, the population rate stays at its maximum level. When per capita consumption falls below the minimum, the population crashes.

Multiplying the size of the population by the ideality (as a fraction) for any given year results in a measure of the magnitude and quality of our experience as a species. Normalizing these values to the value for a particular year, yielding what I’ll call the “Ideal World Index” (IWI), allows us to compare experiences over time: the higher the IWI, the better we’re doing. Based arbitrarily on the year 2000, the IWI is projected to rise to 1.5 (times what the product of population and ideality was in 2000) by 2038, drop to 0.05 by 2144, and then rise to 20.4 where the per capita consumption drops below minimum (0.09 hectare) and the population crashes.

If the IWI is summed over infinite time (or a sufficiently long period) different scenarios can be compared. Those scenarios with a fixed IWIsum will have the population crash, while those that have a minimum value indicate that the population is sustainable. I have chosen the period from 2000 to 5000 for the scenarios I’ve studied. For all cases where resources are growing as long as possible, per capita consumption falls below the minimum by the year 4500.

Sunday, December 16, 2007

Consumption and Population

At the heart of my dire projections of the world population’s peak and decline has been the apparent parabolic relationship between cumulative consumption and population. As each year’s consumption is added together, population grows to a maximum and then drops to zero. This implies that there is a maximum amount of total resources that we can consume, beyond which more people will die than are being born.

I have now created a theoretical model which explains this relationship, showing the parabolic relationship to be only an approximation.

Consider a system with a fixed amount of resources, of which a maximum amount can be replenished each year (the “capacity,” which increases exponentially each year). The world population has a basic, exponential rate of growth that it attempts to maintain. Each person consumes a certain amount of resources each year, which increases exponentially. As long as the amount of resources consumed by the entire population does not exceed the capacity, the amount of resources doesn’t change; if it does, then the amount of resources decreases by an amount equal to the excess. If the amount of resources changes then the population adjusts itself in proportion to the change (that is, if the resources decrease by one percent in a year, the population after its basic rate is applied also decreases by one percent).

The best fit of the model to the data starts in 1961 with a population growth rate of 2.0 percent, capacity growth rate of 0.5 percent, 2,800 billion hectares of resources, per capita consumption at 1.44 hectares, growth in per capita consumption at 1.6 percent, and a capacity of 3 billion hectares. When this model is applied to footprint and population data, the world’s population peaks in 2035 at 8.4 billion people, and drops to under one billion people by 2093, reaching zero by 2287.

Friday, December 14, 2007

Fighting Global Warming

It is important to focus on the main problem of a high ecological footprint, rather than mitigating the more obvious consequences of any particular part of that footprint. In the case of carbon dioxide, much of the public focus has been on dealing with global warming by reducing direct carbon dioxide emissions, while some technologists have sought to address the “warming” part by proposing the decrease of sunlight striking the Earth through cloud seeding or orbital sun shields.

Any “solution” to global warming must keep the overall ecological footprint from growing; otherwise, the solution might be as harmful as the problem.

Carbon dioxide emissions currently account for an estimated 76 percent of the maximum sustainable footprint (MSF), while other components of the ecological footprint (grazing land, fishing, forest use, nuclear, built up land, and crops) account for an additional 83 percent. Of the other components, crops have the greatest potential of growing in their impact on the environment: At 34 percent of the MSF, my projections show this component taking up an entire maximum sustainable footprint by itself in 2037 (carbon dioxide by that time will be 137 percent, with the remaining components summing up to 85 percent). One of the most popular proposals for dealing with global warming is to grow organic fuel to replace gasoline, since fossil fuel burning is the main contributor of our carbon dioxide emissions. Growing more crops for ethanol replacement of gasoline would necessarily increase cropland, and add to its ecological footprint. If the condition for our population crashing is having the ecologic footprint exceed the surface area of the Earth, then my worst-case projections do not rule out this component being able to kill us all by itself.

Thursday, December 13, 2007

Reducing Carbon Dioxide

At an estimated 7.2 billion hectares, carbon dioxide emitted from fossil fuel use is the largest contribution to humanity’s ecological footprint (more than double its nearest competitor, cropland). Indeed, of all the impacts we have on the planet, carbon dioxide is the only one that is identifiably and totally waste; and its destructive effects are well documented (global warming). If we could magically remove this impact, natural systems could easily support us and other species – humanity would be below the maximum sustainable footprint (currently 9.5 billion hectares).

If current trends continue, then by the early 2020s the footprint from carbon dioxide emissions alone will equal the maximum sustainable footprint (at that time, due to projected increases in bio-productive land, about 10.3 billion hectares). It is perhaps no coincidence that by then our population will have passed its peak.

Sunday, December 9, 2007

Green Hectares

Of the estimated 11.5 billion hectares of bio-productive area in the world, a minimum of 2.1 billion hectares is necessary to preserve biodiversity. Humanity has overshot what’s available, using 15.9 of the maximum 9.5 billion hectares that we should be using (in an ideal world); this leaves at least 6.4 billion hectares that must either be reclaimed or replaced without using more.

With a population of 6.6 billion people, each of us should be using no more than an average of 1.4 hectares (3.5 acres); instead we’re using 2.4 hectares (5.9 acres). If current trends continue, the population will peak in 2020 with the average person using 3.3 hectares (8.3 acres) instead of practically the same amount we should be using today. The last time the world per capita footprint was 1.4 hectares, John F. Kennedy was president of the United States and the world was using half of its biocapacity.

We can’t go back to the early 1960s, nor would we want to. Carbon dioxide emissions from our depleting fossil fuel supply use up half of our global footprint, and these will need to be cut drastically to mitigate global warming. Alternatives to the cheap energy supply that was taken for granted in Kennedy’s era will be much different, if successfully exploited. With the need to make more land wild and common resources such as air and water cleaner, energy and the civilization it enables will be much more a part of Nature than a total break from it.

One thing that might be similar to Kennedy’s time involves sending a breeding population to Mars. At a cost of 110 million hectares each year over the decade or so we may have left before our population peaks, Earth’s life would have an insurance policy in place should we fail and civilization crashes.

Saturday, December 8, 2007


By 1998, humanity was using the biological equivalent of one-fourth of Earth’s surface area, four percent more than the area taken up by land and three percent more than the amount that was ecologically productive.

By 2020, the amount of ecologically productive land will have grown to 24 percent of the planet’s surface area, while the amount used by humanity will have grown to 47 percent. In that year, like what happened to other species in 1975, our population will begin to decrease.

If our use of resources continues to increase after that, our population will continue dropping, approaching zero in 2048, when we would be annually using twice the amount we were at our peak, or nearly the entire surface of the Earth.

In an ideal world, we all would recognize these facts, and be taking appropriate action both further increase the amount of bio-productive land and shrink our consumption so that we and other species can live on that amount.

The rate of growth of resource use (including rendering unusable by waste) is falling, but not fast enough to avoid disaster. We are now using 167 percent of the bio-productive land we should be using to live sustainably with other species, which means that today we should be using 60 percent of the natural resources that we are. Each year we wait, if current trends continue, that fraction will decrease by about one percent, falling to 50 percent by 2014.

Revised Deficits

Taking another look at the concept of “unprocessed waste” described in the previous post, I now realize that the ecological footprint already includes that waste in its definition. That is, unprocessed waste is really the difference between the footprint and the biocapacity.

By this more correct definition, our footprint will exceed available biocapacity by an amount equal to that biocapacity (that is, our waste will equal the world’s biocapacity) when my consumption model projects our population to peak.

Using the ratio of Gross World Product to ecological footprint as a measure of the value of each unit of bio-productive land, the 1997 value of available biocapacity comes close to the high end of the benchmark value of Nature’s services: $43 trillion (in 2007 dollars) by my new estimate, versus $28T to $45T in the benchmark estimate. The value of the fraction of biocapacity usable by humans while accommodating other species in 1997 would have been $36T by my estimate, marking the maximum GWP we could have had to keep other species from dying off.

I estimate that the current maximum GWP for accommodating other species is $41T, and project our actual GWP to be $66 T; with a difference of $25 T (matching the “maximum Nature deficit” I calculated using fixed biocapacity). Without other species, the maximum GWP is the current value of biocapacity, or $48 T, with a deficit of $18 T (versus the $9 T that I estimated earlier). In ecological terms, we have an estimated footprint of nearly 15.9 billion global hectares (Bh) and a biocapacity of 11.5 Bh, of which other species need 2.1 Bh.

Thursday, December 6, 2007

Accumulating Waste

In my previous analyses, I assumed a constant biocapacity – the total available amount of bio-productive land on Earth – equal to its 2003 value (as stated in the World Wildlife Fund’s Living Planet Report 2006, where much of my data comes from). In fact, biocapacity has been growing, though much slower than the global ecological footprint (an accrued 0.5 percent per year since 1961, versus 2.8 percent for the footprint).

When the great die-off of other species started, the ratio of available resources to total biocapacity was 18 percent. Since the late 1980s, humans have exceeded the available biocapacity; and like trash piling up in the street because the trash collectors are out sick, the difference remains unprocessed. By 1999, the amount of unprocessed waste equaled our ecological footprint, and by 2005 the unprocessed waste was double the resources we consumed in a year (currently the ratio is about 2.5).

If every hectare had the biological productivity of an average hectare in 2003, it would take the entire surface area of the Earth (including the oceans) to process the waste we will have accumulated by 2010. By 2014, we will need 1.5 Earths to process our waste; this is the year my projections show the populations of other species crashing. By 2021, as our own population peaks, we will need three Earths to process 6.3 times our annual consumption.

Monday, December 3, 2007

The Great Die-Off

The year 1975 may turn out to be one of the most pivotal in history. At or around that time, the populations of other species, according to the World Wildlife Fund’s Living Planet Index, began to drop precipitously.

Meanwhile, the amount of bio-productive land consumed by humans (the ecological footprint) was eight billion global hectares and growing exponentially. By next year, that number will have doubled and the LPI may have fallen to half of its 1975 level.

If we could suddenly replace all of the land and other resources we have taken out of service to Nature along with the creatures we have killed, then with our larger population the average person would be consuming less than one and a quarter hectares, or half of today’s average value. It can’t be stressed enough that simply cutting back our present consumption by that much will only buy time until our own population peaks; we must actively repair or replace what we’ve taken already.

Saturday, December 1, 2007

Economic Growth and the Natural Deficit

To replace the services we have removed by destroying natural capital, the world would need to add at least $27 trillion to this year’s Gross World Product. Each year we wait, the deficit will grow by an additional $2T. The maximum level of GWP that we can sustain in addition to providing natural services is about $40T.

The above numbers do not reflect what it would take to accommodate the populations of species that existed before the rapid die-off that started in 1975. Assuming we could replace them on a human time scale, we would need to spend an additional $15T (our current deficit would be $42T), and our maximum allowable GWP would be only $24T.

With our natural deficit growing each year by twice the current total cost of the Iraq Occupation, we are facing a far more critical challenge than any so-called “War on Terror.” If we were to deal with the deficit by growing the economy to fix or replace natural systems in the time we have remaining, GWP would need to increase by 140 percent by 2020 (for only our species) or 163 percent by 2013 (for all species). If the growth was done exponentially, GWP would need to grow annually by 2.6 percent for us and 8.5 percent for all species over the respective intervals of time. For reference, the current GWP growth rate is an estimated 2.8 percent.