Since the end of WWII, the world's population doubled and the global economy grew seven-fold. While military violence and weapons continue to threaten people's health and security, increasingly fears for humanity's safety look to day-to-day issues for the seeds of future disaster.

One of the first things we need to learn is the opportunity cost for each human on the planet. In other words, what resources are used up by every human on the planet? (Some analysts call this issue the earth's carrying capacity.) Of course there is no easy answer as each human uses resources at a different rate.

But for a easy start to the issue: Check out EarthNetwork's "footprint" quiz to see how many resources you use. Be prepared to share your results.

Water

• Approximately 70% of all available water is used for irrigation.
• Current global water withdrawals for irrigation are estimated at about 2,000 to 2,555 km3 per year.
• Irrigated area as a proportion or irrigation potential in 1999:
      - World: 50%
      - Sub-Saharan Africa: 13%
      - South Asia: more than 85%.
• Poor drainage and irrigation practices have led to waterlogging and salinization of approximately 10% of the world's irrigated lands.
• "With water worth easily 70 times as much in industry as in agriculture, farmers almost always lose in the competition with cities."
  

source: Lester Brown, at Earth Policy, Institute

image source: www.cleverhome.com

UNESCO: Water requirement equivalent of main food products

This table gives examples of water required per unit of major food product produced, including livestock, which consume the most water per unit. Cereals, oil crops, and pulses, roots and tubers consume far less water.
[Figure source]: Extracted from the Executive Summary of the WWDR. FAO, 1997. Water Resources of the Near East Region: A Review. Rome.

For an amazing collection of maps regarding water, irrigation and uses of water per capita, check out World Water Development Report

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Production of food is a highly water-consuming activity. In developing countries, agriculture accounts for 70-90% of available freshwater supplies. Also, remember that much water is wasted in current agricultural practices through evaporation. SIWI Senior Scientist Malin Falkenmark says that astonishingly huge volumes of water are transformed into vapour during the food production process. Ms. Falkenmark also makes the point that while you consume only small amounts of water as water, the food you ate required several times that amount to produce: “With prevailing land and water management practices, a balanced diet requires 1,200,000 litres of water per person per year (3287 liters per day) - 70 times more than the 50 liters per day used for an average households domestic needs.”

Source: New Nation

image source: www.hrwallingford.co.uk/ projects/GWP/

Soil/Land

From the beginning of agriculture until 1950 or so, growth in world food production came almost entirely from expanding the cultivated area. Rises in land productivity were negligible, scarcely perceptible from one generation to the next. Then as the frontiers of agricultural settlement disappeared, the world began systematically to raise land productivity. Between 1950 and 2000, grainland productivity climbed 160% while the area planted in grain expanded only 14%.
This extraordinary rise in productivity, combined with the modest expansion of cultivated area, enabled farmers to triple the grain harvest over the last half-century. At the same time, the growing demand for animal protein was being satisfied largely by a quintupling of the world fish catch to 95 million tons and a doubling of world beef and mutton production, largely from rangelands. These gains not only supported a growth in population from 2.5 billion to 6.1 billion, they also raised food consumption per person, shrinking the share who were hungry.

Source: Lester Brown

image source: http://topsoil.nserl.purdue.edu/nserlweb/isco99/isco99toc.htm

• Pasture and crops take up 37% of the Earth's land area

image source: texaco.com

• Land in agricultural use has increased by 12% since the 1960s to about 1.5 billion hectares.

Clearly, we have made great strides in the efficiency of cultivation. To achieve those results requires study. To look at one country's examination of the issues of cultivation see a New Zealand site.

Despite the good news regarding cultivation and productivity, soil quality is decreasing. This image comes from a GLASOD study on soil erosion and its effects to the world. Top soil or dirt should be considered a precious commodity. Its existence at all on our planet distinguishes it from other planets in our solar system and is in may ways a finite resource. Go to this site to learn about soil erosion, where it occurs and what happens when it does.

Air Quality

source:EPA

Although stabilizing atmospheric CO2 levels is a staggering challenge, it is entirely doable. Detailed studies by governments and by various environmental groups are beginning to reveal the potential for reducing carbon emissions while saving money in the process. With advances in wind turbine design and the evolution of the fuel cell, we now have the basic technologies needed to shift quickly from a carbon-based to a hydrogen-based energy economy. Cutting world carbon emissions in half by 2015 is entirely within range. Ambitious though this might seem, it is commensurate with the threat that climate change poses.

Source: Lester Brown

For more on this topic, feel free to check out UC Berkeley's ELSI site UC Berkeley created the site specifically for high school students to increase their understanding of the science involved with air quality.

Climate change will affect you in various ways. Take the EPA's quiz and see what you know! Again, be prepared to share your results.

image source: UC Berkeley, Lawrence Livermore Lab

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Population:

There is a very clear connection between population growth and virtually every challenge facing our planet.

U.N. projections show world population growth under three different assumptions about fertility levels. The medium projection, the one most commonly used, has world population reaching 8.9 billion by 2050. The high projection has population going to 10.6 billion. The low projection, which has population peaking at 7.5 billion in 2039 and then declining, assumes that the world will quickly move below replacement-level fertility to 1.7 children per couple. If the goal is to eradicate hunger and illiteracy, we have little choice but to strive for the lower projection.

The benefits of restricting family size have been examined in real time in Bangladesh, where analysts concluded that the $62 spent by the government to prevent an unwanted birth saved $615 on other social services. Investing in reproductive health and family planning leaves more government resources for education and health care. These numbers suggest that, for rich countries that donate aid, providing the additional $10 billion or so needed to ensure that all couples who wanted to limit family size have access to the services they need would yield high social returns in improved education and health care.

Source: Lester Brown

image source: http://www.guardian.co.uk/population/0,2759,184290,00.html

All the following facts came from Population Connection. They give a quick synopsis of the demographic issues facing our planet.

• Between 2005 and 2050, eight countries — India, Pakistan, Nigeria, Congo, Bangladesh, Uganda, the United States, Ethiopia, and China — are likely to contribute half of the world’s population increase.
  Source: UN Population Division
• At the annual growth rate of 1.2 percent, world population increased by 76 million people in 2004.
  Source: Earth Policy Institute
• U.S. population is expected to rise 43 percent by 2050 -- from 293 million today to 420 million.
  Source: Population Reference Bureau
• By 2050, three of every four developing nations will probably have stabilized their populations.
  Source: Boston Globe
• U.N. medium-range population estimates for 2050 are down from 9.4 billion to 8.9 billion. The U.N. estimates population might stabilize at 9 billion by 2300.
  Source: U.N. Population Division

image source: www.greatdreams.com/ population.htm