To conclude this book, I would like to present my personal proposal for what we should do to make our civilization sustainable. There are three major problems, namely the restriction of population growth, the maintenance and restoration of vegetation, and the utilization of renewable energy.

How long can our civilization flourish? Will our civilization remain thousands of years hence? During the Cold War the greatest threat to humans was nuclear annihilation, but today it is the environmental problem. Many people are afraid that global warming might collapse our civilization. In 1997, COP3 adopted the Kyoto Protocol to reduce greenhouse gas emissions, but the U.S. and Australia have declined to ratify the agreement. It has turned out a failure. In this page, I analyze the problems of the Kyoto Protocol and propose an alternative feasible framework that reduces greenhouse gasses.

People expect that a hydrogen-powered fuel cell engine will take the place of an oil-powered internal combustion engine because the former is superior to the latter in many respects. Is it really so?

About one-third of the world's land surface is arid or semi-arid. The Earth's landmasses are losing 24 billion tons of topsoil and making 12 million hectares of the Earth useless for cultivation every year. The desertification is, however, not necessarily anthropogenic. So, first, we must elucidate what are the natural conditions of the desert. Then we can identify what are the artificial causes of desertification.

Today, global warming is the most popular topic of all environmental problems. It was one of the major themes talked at the 33rd G8 summit held at Heiligendamm, Germany, in 2007, where they issued a communiqué announcing that the G8 nations would aim to at least halve global emissions of carbon dioxide by 2050. Is global warming so serious? If so, why is it serious? The 1st chapter of this part recognizes the status quo of the current climate change. The 2nd chapter searches for its cause. The 3rd chapter assesses its impact on us.

There are many environmental problems that threaten the sustainability of our civilization, namely, the problems of pollution, global warming, and desertification. In this part, I first analyze the problems of pollution in terms of entropy. I first define what pollution in general is and then examine the feasibility of material recycling and energy recovery of waste as the solution of waste disposal.

Cooling centralizes systems, while warming decentralizes them. The modern Little Ice Age centralized social systems, but the contemporary global warming decentralizes them. In this chapter, I will divide social systems into informational, political and economic systems according to three exchange media and examine the modern centralization and the contemporary decentralization.

Since the survival of our systems depends on getting the low-entropy resource from the environment, throwing the high-entropy waste into the environment, and maintaining the low-entropy structure against the environment, the fluctuation of the environment has modified the history of humans. Environmental history is now in fashion in conjunction with the rise of environmentalism, but I would like to reconstruct environmental history in terms of my theory of entropy described in the previous part.

The shortage of natural resources and the destruction of the natural environment are two big problems that are now threatening our existence. These two problems are actually just one problem ― the problem of entropy. In this part, I will show that the essence of the two problems is entropy and the key to resolving them consists in how to decrease entropy. So, first, let me explain what entropy is.

The modern civilization that originated from the Industrial Revolution is now spreading throughout the world. The demand for natural resources is rapidly increasing and the environmental problems are getting globally more and more serious. Our civilization seems hardly sustainable. What should we do to make it sustainable? This book establishes the fundamental theory of the civilization, analyzes the problems of resources and the environment in terms of entropy, and suggests a solution to them.