The environmental damage wreaked by modern intensive agricultural and fishing practices is huge. Increasing the pressure on the environment courts catastrophe.
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In the 1960s the Club of Rome and other notable commentators such as Paul Ehrlich predicted that the world's rapidly expanding population could not be fed in the near future and that mass starvation may occur. However, such dire predictions were scoffed at by many and subsequently proven wrong in the shorter term in the following decades by the Green Revolution with the introduction of high yielding crops. However, these high yields were only possible through the greater associated use of irrigation and fertilizers. Now it appears that this has come at a price, the very high price of environmental degradation that we are now paying:
The recent FAO report
entitled Livestock's long shadow, noted
Vital statistics of the livestock industry overall (Steinfeld 06):
Resource consumption on a huge scale. High yielding crops are dependent of the use of large amounts of fertilizer, pesticides and water as shown in the following table (Adapted from D'Antonio 01):
Using vast amounts of water for needless production of animal
protein by profit-hungry vertically-integrated multinational
agribusinesses is a luxury the world cannot afford. See the
Water pollution from slaughter houses is also very substantial particularly in the developing world. Industrial scale livestock production is usually associated with large scale slaughtering facilities. While the machinery inside such facilities is often imported, the associated waste processing technology isn't with large amounts of material such as rumen content, blood and fat dumped into the environment.
Sediment in water from agriculture is a major pollutant. Annually 25 billion tonnes enters rivers world wide. The livestock sector is one of the major contributors to this, either directly or indirectly from feedcrop production (Steinfeld 06). See below under soil erosion.
Eighteen percent of all greenhouse gas production (in CO2 equivalents) comes from livestock. This figure includes the effect of pasture degradation and land use (Steinfeld 06)(McMichael 07).
Livestock production is a large contributor to CO2
emissions (Adapted from Steinfeld 06):
When land clearance is included, CO2 emissions from livestock account for about 9% of total anthropogenic CO2 emissions (2.7 billion tonnes per year out of a total of 31 billion tonnes per year).
Other greenhouse gas emissions from animal production. Worldwide ruminant livestock account for 37% of annual methane emissions and 65 of nitrous oxide (Steinfeld 06). Methane's importance is increased markedly because a little bit of methane goes a long way: every molecule of methane has the same greenhouse effect as that of 23 molecules of carbon dioxide. It has been estimated that methane production world wide from ruminants is around 86 million tonnes from rumens and a further 18 million tonnes from manure (Steinfeld 06). Methane levels have risen more dramatically than CO2, having more than doubled in the last century from around 800ppm to 1755 ppm in 2004 compared to the 25% increase of CO2. It must be noted that methane levels over the last few years have been relatively stable related mainly to a reduction of methane production by the drying up of wetlands which has counterbalanced the increasing man made methane emissions (Bousquet 06).
Methane's half life in the atmosphere is relatively short at around 12 years compared CO2 much of which is retained in the atmosphere for more than 80years (Hanson 06). Because of methane's short life span and its powerful greenhouse gas effect, moves to reduce methane production, particularly by limiting the production from animals, is likely to have a relatively greater effect than efforts to reduce CO2 in the shorter term. This is a strong argument for moving to a more plant based diet.
Ammonia gas production from manure and urine as well as from fertilizers add greatly to the nitrate pollution of water and subsequent eutrophication. Close up, ammonia gas is unpleasant to breath in, but its distant effects are much worse. Large amounts are produced from animal manure and to a lesser extent from the volatization of chemical fertilizers. Most of the atmospheric ammonia is quickly returned to the earth where it acts as a significant pollutant. Around 47 million tonnes are released into the environment annually from human-related activities with around 65% coming from livestock production (Steinfeld 06). As example, on the Delmarva Peninsula adjacent to Chesapeake Bay in the eastern US, there are 600 million chickens producing around 20,000 tonnes of per year. An estimated 27% of this ends up in the bay (Jacobson 06).
Nitrous oxide (N2O) is an even more powerful green house gas and substantial amounts come from fertilizers and manure. Nitrous oxide, molecule for molecule, has 200 times the effect of carbon dioxide as a greenhouse gas and in addition is extremely long lived in the atmosphere lasting anything up to 150 years. It also depletes the stratospheric ozone layer which protects the world from excessive harmful ultraviolet radiation. A doubling of the N2O would result in a 10% decrease in the ozone layer and a 20% increase of the UV radiation striking the earth. The current increase since the industrial revolution is around 16% (Steinfeld 06). However, it doesn't end there. A lot of this ends up as nitrate pollution in water, causing eutrophication. The largest livestock related source of nitrous oxide is animal manure and world wide it is estimated at 3.69 million tonnes per year (Steinfeld 06).
picture of livestock production in relation to greenhouse gases.
These figures include the contribution from land use change
Overall livestock production contributes around 18% to total greenhouse gas production. It should be noted that a substantial proportion of this is related to land clearance practices to extend pastures particularly in South America. Controlling this clearance directly by better local regulation or indirectly by reducing the demand for animal products are urgently required.
Nitric oxide (NO) comes mainly from burning fossil fuels but significant amounts also come from the action of soil bacteria on nitrogen containing compounds. This along with nitrogen dioxide, has a number of unwanted effects: increase in lower atmospheric ozone, decrease upper level ozone, photochemical smog and acid rain. See the section on manure.
Smell: an unpleasant neighbour. The smell arising from these huge intensive animal production units is very unpleasant and while not a significant health risk, none-the-less degrade the environment for humans.
of the nitrogen cycle: it is being severely
damaged by man made fertilizers and other human activities.
Fertilizer use to produce animal-based foods is very large (Modified from Jacobson 06).
What is the
effect of all this extra nitrogen?
The global size of the problem is huge, year 2000 figures (Eswaran 01)
Estimates of the proportion of various land types that have been degraded quoting various studies (Steinfeld 06).
the US, 55% of the erosion of crop and pasture land is related
to livestock either directly or indirectly from growing
feedcrops (Steinfeld 06).
The areas with the highest potential are in red, those with the lowest in green and land areas in white were not considered in this analysis. Yellow and orange are intermediate. As can be seen high risk soil erosion areas dominate the non-desert areas of the world. As noted elsewhere, much of this is related to livestock production.
Soil should be viewed as a non-renewable resource, a resource that we are using up through excessive consumption animal-based foods coupled with unwise farming practices.
Effects of soil erosion (also see the section on water)
Soil loss from tillage of crops. Despite recent advances from the adoption of minimal or no tillage, there are still very substantial losses from erosion. Some crops are associated with greater losses because they supply less ground cover. For example soy and corn grown in rows provides less cover to prevent erosion than compared to small grained crops such as wheat which are not grown in rows. Because of the massive amounts of soy produced in the world today for intensive feed lot operations, this is a very significant problem. Soil erosion not only reduces the productivity of the land but also the run off sediment blocks drainage ditches, fills dams with silt, and pollutes streams and rivers. The problems are directly related to the amount of land under cultivation. That area has been increasing around the world in the last decades (see the above table), much of it related to the increasing use of crops to feed animals rather than being used to feed humans directly. This is very wasteful and in the longer term unsustainable.
Soil erosion increases water loss and wastage. This is probably the most significant effect of all since eroded soils are less absorbent of rain water, where more than 80% of water is lost to excessive run off. (Pimentel 04)
Soil compaction and erosion from
large free-range animals Soil
compaction and erosion caused by hard hoofed animals in fragile
landscapes is causing substantial damage. Forage is often
concentrated around water sources. Studies in the US rangelands have
shown that while these riparian areas represent 1.9% of grazing
land, they produce 21% of the forage and 81% of forage consumed by
cattle. This concentrates the damage in this fragile zones greatly
increasing erosion. Also, compaction of soil stops
water penetration leading to increased run off and erosion as well
as reducing aquifer replenishment. Lowering the water table then
lowers stream water level, increasing the bank height and further
increasing erosion from cattle, setting up a vicious cycle
Soil compaction also occurs from agricultural machinery. This has been a significant problem in the past but due to better farming methods this has been reduced, but in many parts of the world remains a substantial problem. The heavier the machinery, the greater the problem, not necessarily overcome with dual or balloon tyres. As agriculture has become more industrialized to meet the demands of intensive animal feedlots, machinery has tended to become much bigger for economies of scale, promoting this problem. There are many factors that can moderate this effect but good crop rotation, adding more organic matter to the soil and minimal tillage are effective measures (Compaction 06).
The spread of woody weeds is promoted by cattle grazing. Cattle are selective in what they eat, often eating down the more palatable native plants and leaving the unpalatable small woody trees along with other exotic species. Overgrazing along with competition for water and sunlight reduces ground cover grasses leading to wind and water erosion of the exposed earth. Also cattle often distribute the seeds of these plants which become attached to their hides and the surface damage of their hooves promotes planting of the seeds. Fires which will reduce woody weeds are suppressed in an attempt to maintain pasture in the shorter term but in the longer term such moves are counterproductive. The spread of woody weeds has caused major degradation of enormous tracts of land in many countries (Steinfeld 06). The only effective measure is to reduce livestock numbers by reducing demand for animal products.
Prolonged grazing can lead to a further reduction in the existing tree cover. A survey done in Australia has shown that continuous grazing kills new tree growth with the older trees not being replaced as they die. In some areas tree numbers have dropped alarmingly. A simple answer to this is to introduce rotational grazing with individual areas intensively grazed for short periods with long periods of rest in between. (Fischer 09)
Pollution of soils by heavy metals - the roxarsone story. There has been some concern that heavy metals such as cadmium are being added to the environment through fertilizers. As small amount is added through the use of rock phosphate based fertilizers, but this is probably less important than other processes. Roxarsone is an organic arsenical compound added to chicken feed to prevent coccidial gut infections and hence acts as a general growth promoter. This compound is not absorbed by the chickens and hence there is no significant arsenic contamination of chicken products. However, the compound is passed unchanged in the litter which are then spread onto land for disposal.
What has become apparent in recent times is that there is considerable bioconversion of this compound to inorganic arsenates and arsenites. As roxarsone is water soluble, its potential to spread in ground water is large. Roxarsone is widely used around the world. More than 900 tonnes of it is released into the environment every year in the US. Chicken litter often contains 48mg/kg of arsenic. Land that has been used for such litter disposal has been shown to have substantially higher levels of arsenic. This is a cause of great concern (Cortinas 06).
Many other metals are used in intensive production units. Copper, zinc, selenium, cadmium, cobalt, iron and manganese are various used and much of this ends up as environmental contaminants (Steinfeld 06).
Salinization is a huge problem, particularly in lands where irrigation is used. Up to a third of the world's land is either affected or vulnerable. There are a number of different mechanisms causing salinization of land: evaporation of irrigation water, rising water tables either directly from irrigation or by the removal of trees for cropping/pasture. In rain fed crop lands, build up of salt is usually not a problem since the rain water flushes the salt away. Where water is applied to crops via irrigation, the dissolved salts in the irrigation water are progressively concentrated by the evaporation and transpiration of the applied water. This results in a paradox. Where water is applied by low volume methods such as drip irrigation, no water is available for flushing, the salt builds up. Where large volumes are used, build up of salt is reduced because of flushing (Pimentel 04).
Irrigation water can cause the water table to rise considerably. If the underlying ground has high levels of salt, this is dissolved in the rising water table and brought to the surface, eventually making the ground non-productive. Large areas of Australia, being once a inland sea, suffer from this problem. Finally, the water table can rise because of the removal of trees which keep the water table lower by extracting water which is then lost by transpiration. The rising water table brings with it large amounts of salt (White 97). Run off from these operations takes large amounts of liberated salt leading to rises in salinity of many rivers. In Australia, the Murray River is becoming more and more salty so that cities such as Adelaide closer to its mouth and which draw substantial amounts of drinking water from it, are likely to run into problems in the not too distant future.
Waterlogging from irrigation reduces productivity: water in the wrong place. Up to 60% or the water intended for the plants doesn't reach them. If drainage is not good, this water accumulates in the upper soil levels and once it has risen to root level, productivity drops. As example 8.5 million hectares of land in India are affected by this, with a reduced yield around 2 million tonnes per annum (Pimentel 04).
Deforestation leads to long term reduction in rainfall. It has recently proposed that with the cutting down of trees, the amount of transpired water vapour is proportionally reduced. Transpired water vapour condenses above forests, forming water droplets which occupy a much smaller volume than the water vapour. This then reduces air pressure so that adjacent air is drawn in. In regions that have major forests, this sucking in effect can be very substantial, drawing in moist air from the oceans to areas considerable distances inland were trees are growing. When such forests are converted to pastures or crop land, this effect is cancelled so that the rainfall is subsequently reduced. (Makarieva 09) Such a mechanism has been proposed for some of the rainfall reduction in south eastern and south western Australia, however many other regions of the world are also likely to have been adversely affected by this mechanism for example, south western USA, many parts of Africa and China. Deforestation can also reduce rainfall by other mechanisms such as the loss of air turbulance from trees and changes in albedo associated with the move to cropping/pastures.
Humans have caused a massive expansion in a very limited number of species including ourselves. Less than 20 staple plant species supply the vast majority of plant-based foods and only 14 animal species supply 90% of animal-based foods. When put together, this represents a very substantial proportion of the world's biota leaving much less room for the estimated 14 million species that occupy the world.
Loss or severe degrading of the following habitats has been proceeding rapidly, much of it related to livestock production and aquaculture:
Other mechanisms of loss of biodiversity.
Many fisheries are in steep decline or have been wiped out. Globally, the number of fishery collapses (defined as catches less than 10% or the historic maximum) have been accelerating with 29% of fisheries in large marine ecosystems in this category in 2003. If individual fish taxa are considered, around 65% of species are in this category (Worm 06).
The overall catch has declined more slowly because as fishing fleets having depleted one species they move onto another thus tending to maintain the overall catch. As example, following the collapse of the Canadian cod fishery, the number of crustaceans caught increased substantially. Most fisheries are below their historic maximum catches, for example Canada at 40%, US at 55% and the EU at 60% (Hilborn 03) forcing the large European fleets to move further afield. Worldwide, despite large increases in fishing effort, cumulative yields across all species has declined by 13% since the peak in 1994 (Worm 06). Further evidence has been illustrated recently on the Good website (www.good.is) with the following transparency.
Some commentators argue that this doesn't
necessarily indicate that these fisheries will collapse but instead a new equilibrium
will be gained with lower or different catches. This can be seen in the highly exploited Mediterranean (Hilborn 03).
However, many disagree with such assessments. For an excellent review of the negative aspects of world
wide fisheries, download "Fish Dish: Exposing the unacceptable face
of seafood" from the World Wildlife Fund site (WWF 06). If for example the exhortations to eat more fish as part
of a healthy diet were put into effect, serious short falls in
supply would occur and the temptation to over exploit would
increase. Current estimates
would indicate that if major conservation programs are not put
in place to conserve major marine fish stocks, close to 100% of all
fisheries will collapse by the mid 21st century (Worm 06).
types take surprisingly long times of decades to reach this stage
and are readily threatened by even moderate fishing such as the
orange roughy or the Patagonian tooth fish. Finally high demand and
high prices have led to the use of cyanide fishing practiced
illegally in many parts of SE Asia which lays waste to the whole
environment. Often times these people are forced into this situation
through desperation because of declining fish stocks associated with
poorly regulated industrial fishing.
The damage done by bottom trawling has only recently been appreciated. Because no one in the past looked very carefully, the damage done to sea bed habitats was ignored. Recent studies have shown long term damage in places to these fragile habitats and a minority of may recover (Hilborn 03). However, most sustain substantial damage with a reduction of species richness which in turn reduces productivity(Worm 06). Bottom trawling lead to a permanent change in the marine fauna, with scavenger species favoured. This leads to further pressure on other species because of predation on juveniles. Many jurisdictions have imposed controls on this type of fishery but in less well regulated parts of the world, it remains a significant problem.
Injury to wild life has been extensive. This has been widely publicized and public pressure has been placed pressure on some fisheries, many problems remain. The killing of dolphins and large seabirds has been highlighted and while some changes have occurred, much is still to be done. Here are some examples of the massive toll on wildlife (WWF 06):
Even though there have many
advances in aquaculture, the problems of industrial scale farming
also apply to aquaculture.
It should be noted at the outset, the majority of farmed fish in the
world, located predominantly in China, are fresh water vegetarian
species and are much more environmentally acceptable. Most of the
the table fish favoured in the west are carnivorous. Feeding fish to
fish has always seemed wasteful of natural resources, with around
3kg of feed for every kg of farmed salmon. However, with some
species fishmeal is being augmented with vegetable protein lowering
the pressure on the supply of fish for fishmeal, but this has the
negative effect of reducing omega 3 levels. Many of the improvements
in food conversion ratios has been because of the increasing
proportion of fish oil in feed, but this can alter the flavour of
the fish considerably.
Statistics show that world fishmeal supplies have remained relatively constant for the past 15 years where as farmed fish outputs have increased three fold in the same period. Part of the explanation for this may be that most of the fish stocks used for fishmeal such as sardines, anchovies and capelin, are close to full exploitation, requiring increasing diversion from animal feed uses. However, there is evidence of illegal fishing to bypass the quotas set by many countries to maintain supply in the face of heavy demand. Significant local problems have arisen in association with these fisheries. Reduction in small fish numbers in Chilean waters in part associated with heavy fishing to supply fish farms has led to a substantial reduction in sea bird numbers. Other major environmental problems are shown in the following table:
For an extensive and balanced review of aquaculture of carnivorous fish see the Seaweb report (Seaweb 03).
Overfishing has led to vast jellyfish blooms and declines in fish stocks. In recent years, huge jellyfish blooms have appeared in many parts of the world such as The Gulf of Mexico, The Mediterranean, The North Sea, The Sea of Japan and many parts of S-E Asia. Many fish species feed on junvenile jellyfish and the loss of these predators has allowed jelly fish numbers to increase markedly. In turn, the jellyfish then compete with juvenile fish for plankton and other food sources further reducing fish numbers. For example, sardines target juvenile jellyfish and the massive harvesting of sardines in part for aquaculture has led to a rapid decline in their numbers with a simultaneous increase in jellyfish. Eutrophication has also been a factor in the increase of jellyfish. Jellyfish blooms damage fishing nets, harm fish farms, imperil tourism because swimming becomes unpleasant or dangerous as well as reducing food supply for many communities.Only very small amounts of jellyfish are harvested for human consumption. (Richardson 09)
(Birkehead 05) Charles Birkeland, Paul K. Dayton. The importance in fishery management of leaving the big ones. Trends in Ecology and Evolution 2005;20: 356-358.
(Bohane 06) Ben Bohane. Tiniest nations caught in the net. Sydney Morning Herald 2006 9th October.
(Bousquet 06) P. Bousquet, P Ciais et al. Contribution of anthropogenic and natural sources to atmospheric methane variability. Nature 2006; 443:439-443
(Brashares 04) Justin S. Brashares, Peter Arcese, Moses K. Sam, Peter B. Coppolillo, A. R. E. Sinclair, Andrew Balmford. Bushmeat Hunting, Wildlife Declines, and Fish Supply in West Africa. Science 2004;306:1180-1183
(Compaction 06) University of Nebraska. Management to minimize and reduce soil compaction. Web site at www.ianrpubs.unl.edu
(Cortinas 06) Irail Cortinas, Jim A Field, Mike Kopplin, John R. Garbarino, A.Jay Gandolfi, Reyes Sierra-Alvarez. Anaerobic Biotransformation of Roxarsone and Related N-Substituted Phenylarsonic Acids. Environ. Sci. Technol. 2006, 40, 2951-2957
(D'Antonio 01) Carla D’Antonio, Andrew Dobson, Robert Howarth, David Schindler, William H. Schlesinger, Daniel Simberloff, Deborah Swackhamer. Forecasting Agriculturally Driven Global Environmental Change. Science 2001;292:281-282
(Eswaran 01) Eswaran, H., R. Lal P.F. Reich. Land degradation: an overview. In: Bridges, E.M., I.D. Hannam, L.R. Oldeman, F.W.T. Pening de Vries, S.J. Scherr, and S. Sompatpanit (eds.). Responses to Land Degradation. Proc. 2nd. International Conference on Land Degradation and Desertification, Khon Kaen, Thailand. 2001 Oxford Press (Available on the USDA/NRCS Soils web site www.soils.usda.gov )
(Fischer 09) Joern Fischer, Jenny Stott, Andre Zerger, Garth Warren, Kate Sherren, and Robert I. Forrester. Reversing a tree regeneration crisis in an endangered ecoregion. PNAS 2009; doi/10.1073/pnas.0900110106
(Hanson 06) Jim Hanson. The threat to the planet. Actions required to avert dangerous climate change. Presentation to SOLAR 2006, Denver Colorado.
(Hiborn 03) Ray Hilborn, Trevor A. Branch, Billy Ernst, Arni Magnusson, Carolina V. Minte-Vera, Mark D. Scheuerell, Juan L. Valero. State of the World's Fisheries. Annu. Rev. Environ. Resour. 2003; 28:359–99
(Jacobson 06) Michael Jacobson. Six arguments for a greener diet. Center for Science in the Public Interest 2006, page 81.
(Makareva 09) Anastassia M. Makarieva , Victor G. Gorshkov , Bai-Lian Li. Precipitation on land versus distance from the ocean: Evidence for a forest pump of atmospheric moisture. Ecological Complexity 2009, DOI: 10.1016/j.ecocom.2008.11.004
(McMichael 07) Anthony J McMichael, John W Powles, Colin D Butler, Ricardo Uauy. Food, livestock production, energy, climate change, and health. Lancet 2007; DOI:10.1016/S0140-6736(07)61256-2
(Pimentel 04) David Pimentel, Bonnie Berger, David Filiberto, Michelle Newton, Benjamin Wolfe, Elizabeth Karabinakis, Steven Clark, Elaine Poon, ELizabeth Abbett, Sudha Nandagopal. Water Resources: Agricultural and Environmental Issues. Bioscience 2004; 54: 909-918
(Seaweb 03) MIchael Webber. What price farmed fish: a review of the environment and social costs of farming carnivorous fish. This can be downloaded from www.seaweb.org in the section on Aquaculture feeds and resources.
(Soilcrust 06) US Geological Survey web site on soil crusts. www.soilcrust.org/crust101.htm
(Steinfeld 06) Henning Steinfeld, Pierre Gerber, Tom Wassenaar, Vincent Castel, Mauricio Rosales, Cess de Haan. Livestock's long shadow: environmental issues and options. LEAD/FAO publication 2006. Downloadable from http://www.fao.org/docrep/010/a0701e/a0701e00.HTM
(Richardson 09) Anthony J. Richardson, Andrew Bakun, Graeme C. Hays, Mark J. Gibbons. The jellyfish joyride: causes, consequences and management responses to a more gelatinous future. Trends in Ecology and Evolution 2009;24: 312-322
(Vitousek 97) Peter M. Vitousek, John Aber, Robert W. Howarth, Gene E. Likens, Pamela A. Matson, David W. Schindler, William H. Schlesinger, G. David Tilman. Human Alteration of the Global Nitrogen Cycle: Causes and Consequences. Issues in Ecology 1997;No1:1-16.
(White 97) Mary E. White. LIsten-Our Land is Crying. 1997 Kangaroo Press.
(Worm 06) Boris Worm, Edward B. Barbier, Nicola Beaumont, J. Emmett Duffy, Carl Folke, Benjamin S. Halpern, Jeremy B. C. Jackson, Heike K. Lotze, Fiorenza Micheli, Stephen R. Palumbi, Enric Sala,8 Kimberley A. Selkoe, John J. Stachowicz, Reg Watson. Impacts of Biodiversity Loss on Ocean Ecosystem Services. Science 2006; 314:787-790.
(WWF 06) World Wildlife Fund. Fish dish: Exposing the unacceptable face of seafood. 2006. www.panda.org. in the publications listed in the marine section.