Economic activities inevitably involve some level of material throughput (see Material Throughput). The important question is whether the level of throughput is sustainable with respect to ecosystem functioning. The evidence is clear that the volume and toxicity of material throughput is now in excess of what some ecosystems can bear, and fast approaching the limits for other ecosystems (see Areas of Concern).

Material Throughput Breeds on Itself

Not only does economic growth increase material throughput, but the goods and services produced inevitably lead to the use of yet more energy and materials. This occurs in two ways - goods and services are used, and eventually disposed of. Use involves additional material throughput. The global fleet of cars, trucks, buses, ships and airplanes become vehicles not only for transportation, but also for the throughput of fossil fuels and volumes of additional resources. Once disposed of as waste, the goods produced are often transported over large distances before being buried, incinerated or recycled, all of which requires more material throughput.

 

Increased Quantities of Throughput

• Coal production increased by more than a factor of 500 since 1800
• In the 1990''s economic activities began to rival geological forces in terms of moving more rock and soil than the combined impacts of wind erosion, glaciers, mountain building and oceanic volcanoes
• Today more than 26 billion tons of material are processed globally on an annual basis
• Total industrial production is up over 1500% since 1930
• Since 1800 the total fish catch has increased by over 1000%
• Cattle, pig and poultry populations have increased over 400%, 950 % and 1500%,resepectively, over the period 1890 to 1990
• World meat production has increased about 500% in the last 50 years alone
• Global fertilizer consumption has increased over 1500% since 1930
• World metal production has increased over 1200% since 1930.

Hidden Throughput
In addition to the materials that are counted as part of economic activities, a considerable amount of throughput occurs which has no market value. This ecological rucksack, or hidden throughput, is generally many times the volume or weight of the target material. To produce a 10 gram gold ring, for example, requires the movement of some 3 tonnes of material. The rucksack for coal is at least five times greater than the weight of the coal mined. As the concentrations of valuable ores and minerals decline through depletion, the hidden throughput required to produce the same quantity of ore increases. While these hidden throughputs have no commercial value, they have major impacts on ecosystem functioning.

Exponential Increases in Throughput
The increase in most materials involved in economic activities approximate exponential growth. This means that the increase is proportional to what is already there. This is a much higher rate of growth than a linear increase. When exponential growth occurs, the quantities involved can double very quickly, depending on the rate. Even relatively low growth rates can therefore lead to fairly quick doubling. The longer such exponential growth continues, the shorter the doubling time. The implications for ecosystems is that exponential increases in material throughput will be at a level only half that required to push them beyond sustainable scale just prior to the doubling which produces this level. With substances involving exponential growth, a large safety margin is required to ensure optimal scale (see Scale Policy Implications).

Increasing Toxicity
There are now some 150,000 synthetic compounds in commercial use around the world. Very few have been examined in terms of their potentially harmful effects on living things. It is know that many of these chemicals are carcenogenic, endocrine inhibitors, bioaccumulative, toxic heavy metals or volatile orgainic compounds (see Toxic Substances). The consequences of these toxic substances in our air, water and land are becoming increasingly evident:

• A recent study indicates that 80-90% of all cancers may be envrionmentally induced (US National Institute of Health, 2004)
• 20 to 30 million people have been killed by air pollution since 1980
• The WHO estimates that over 5 million people a year are killed by water pollution
• Pollution is affecting the evolutionary process of natural selection
• In some highly industrialized areas of the world (Brazil, Canada and Siberia), toxic emissions have created virtual moonscapes, which became training grounds for astronauts
• Increases in toxic emissions are occuring exponentially
• Virtually every region of the globe now has traces of industrialized toxins
• The amount of hazardous wastes in the United States increased over 250 times in the latter half of the 20th century
• Various types of radioactive wastes will remain toxic for thousands of years.

The scale of hazardous substances used in economic activities is threatening local, regional and global ecosystems. To operate within sustainable scale the rate of emissions for such substances would have to be no greater than ecosystems can recycle, absorb, or breakdown to harmless components (see Sustainable Or Unsustainable). Unfortunately, just the opposite is happening. For example, under normal levels of acidification soils are able to absorb heavy metals, binding and sequestering them safely. At higher levels of soil acidification (as caused by acid rain), soils loose this capacity. This allows the increasing emissions of heavy metals to enter our water sources, and eventually our food supply.

Wasteful Processes
The flow of material through the various stages of economic acitvity are extremely wasteful. A study conducted for the US National Academy of Engineers reports that some 93% of the materials which enter the production process are emitted as waste. This means that only 7% of the material input acutally enters the products made. Furthermore, some 80% of these products are discarded as waste in a few months time. Only a tiny fraction of the original material from nature provides an ongoing benefit. The devastation of ecosystems may endure for millennium.