in 2009 that ratio had risen to 28%. Looking at the dynamics of calories supplied in Asia during that time, while the total amount of calories supplied from around 1960 to 2007 increased by approximately 1.5 times, the ratio of calories supplied from animal-derived food rose from approximately 7% in 1970 to 15% in 2007. This trend is typical in East Asia, where the total amount of calories supplied has approximately doubled and the ratio of calories supplied by animal-derived food rose three times from 7% in 1970 to 21% in 2007 (Figure 1-2-16).

According to a report by the United Nations' World Water Assessment Programme and Plan (WWAP), in general, if livestock and grain are produced using the same amount of water, livestock is found more inefficient. Specifically, with $ 1 \, m^{3} $ of water, the amount of wheat that can be produced is 0.2–1.2kg, while the amount of corn that can be produced is 0.3–2.0kg, and the amount of beef is 0.03–0.1kg. From now until 2050, it is expected that the demand for grain will increase due to growth in demand for grain for livestock, especially in East Asia, and there are concerns that this may lead to a shortage of water resources (Figure 1-2-17). In fact, there is a broad distribution of areas that suffer from a shortage of water resources, mainly in the west coast of South America, Africa, and Asia, where excessive use of water has led not only to water shortages that will seriously affect people's daily life, but also to a significant decrease of the water levels of lakes and other wetlands.

In summary, the dynamics of dietary habits associated with economic growth affect supply and demand of water resources and as a result may have adverse impacts on a broad range of areas in the environment, the economy, and society. In Japan, it is important to work to preserve water resources and water sources while keeping in mind the status of the world's water resources as mentioned above.

## (4) Mining of Underground Resources, and the Environmental Impact

Underground resources such as mineral resources and fossil fuels are limited. The reserves/production ratio of resources is mostly less than 100 years, specifically, 70 years for iron ore, 20 years for lead, 35 years for copper, 20 years for gold, 15 years for chrome, and 46 years for oil (Figure 1-2-18). If the pace of production continues at its current speed, there is no doubt that the steady supply of underground resources for the current generation will become difficult, or worse, that we may not be able to leave resources for future generations.

In addition, underground resources generate a large amount of mine waste during processing. Some underground resources, even though their collection is technically feasible, may be found in a difficult location or the content rate may be low. In such cases, mining requires a large amount of energy and generates a large amount of waste, thus causing impacts on the environment. This is referred to as the hidden flow, and in order to verify sustainability related to underground resources it is important to also evaluate intermediate resources input for mining and the environmental impact caused by the amount of disposal.

In Japan, although there has been improvement in

Figure 1-2-14 Trends in Area of Land Cultivated for Farming and Amount of Grain Production

Source: Created by the Ministry of the Environment, based on information from FAOSTAT (as of March 2011)

energy and resource conservation thanks to technological progress, a large amount of limited resources still continue to be consumed. Consumption of such resources, especially fossil fuels that cannot be reused after being consumed, iron and copper that are consumed in enormous amounts due to human activities, and mineral resources that are very useful but also very scarce such as rare metals and rare earths, will have a significant impact on our future generations.

Here we will look at copper as an example of hidden flow. Copper plays an important role as a mineral resource that serves as a base for economic development; it is used as electrical wire and various copper-based alloy products in fields of transportation equipment and consumables such as construction, electric equipment, construction machinery, and automobiles. However, its regional distribution is remarkably uneven, and the top 10 mines produce 34% of the world's production. For example, among the 8 copper deposits that have reserves exceeding 10 million tons, 6 deposits are concentrated in Chile. From the perspective of securing stable copper resources, it is important to maintain the amount of production from these vast mines.

In general, the purity of crude ore obtained from mines is approximately 0.8-3% and even after it has been refined into a mineral concentration the purity is approximately 40%, and there are concerns that the quality of copper ore in the world's major currently operating mines is declining (Figure 1-2-19). The purity of copper ore imported by Japan declined from approximately 32% in 2001 to approximately 29% in 2008 (Figure 1-2-20). One of the reasons is that all of the high-quality mineral ore on the Earth's surface layer has already been dug up and now we have to dig to deeper layers where the quality of mineral ore is lower.

Because a decline in the quality of copper ore will lead to an increase in the volume of mine waste from processing of each unit of copper and the amount of energy required to refine the copper, it is also necessary to evaluate the environmental impact caused by mining mineral resources and consider the total material requirement (TMR), including such hidden flows. Trends in TMR show that the TMR value is increasing even though there have not been any major changes in copper