Traditional methods based on mono-disciplinary research or economic growth models cannot solve linked and diversified environmental problems. It requires a holistic view to understand the network of problems and how they are interrelated. In this regard, multidisciplinary and transdisciplinary approaches and models are urgently needed. This paper demonstrates that for ten problems, including population growth, poverty, inequality, wars, refugees, famine, pollution, global warming, loss of nature, and depletion of resources, are interconnected. An integration of the use of eight toolboxes (the energy toolbox, the environment toolbox, the ecology toolbox, pollution control, Pigovian tax, aids to developing countries education and research and family planning) is proposed to provide holistic solutions to examine the networks of complex problems. Due to the linkage of global problems, problems that can be solved directly by toolboxes may result in partially and indirectly settlement of other problems. It should be emphasized that uses of integrated solutions based on several toolboxes are needed to solve the many interacting global problems that we are confronted with.

Hydrogen is expected to play a key role as an energy carrier in future energy systems of the world. As fossil-fuel supplies become scarcer and environmental concerns increase, hydrogen is likely to become an increasingly important chemical energy carrier and eventually may become the principal chemical energy carrier. When most of the world’s energy sources become non-fossil based, hydrogen and electricity are expected to be the two dominant energy carriers for the provision of end-use services. In such a “hydrogen economy,” the two complementary energy carriers, hydrogen and electricity, are used to satisfy most of the requirements of energy consumers. A transition era will bridge the gap between today’s fossil-fuel economy and a hydrogen economy, in which non-fossil-derived hydrogen will be used to extend the lifetime of the world’s fossil fuels—by upgrading heavy oils, for instance—and the infrastructure needed to support a hydrogen economy is gradually developed. In this paper, the role of hydrogen as an energy carrier and hydrogen energy systems’ technologies and their economics are described. Also, the social and political implications of hydrogen energy are examined, and the questions of when and where hydrogen is likely to become important are addressed. Examples are provided to illustrate key points.

Energy crisis is one of the major issues of our society. There are different forms of renewable energy like wind power, geothermal energy, biomass from plants and solar energy. Solar energy is the only freely available source of renewable energy that comes directly from sun and may be converted into heat or electricity. In this article, we develop a model for solar radiation by considering the laminar flow of an incompressible Oldroyd-B fluid toward a thermally and solutally stratified moving surface with nanoparticles and thermal radiation. The data have been computed by homotopic algorithm. The computed solutions of velocity, temperature and nanoparticle concentration are plotted for multiple values of parameters of interest.

China recently announced a plan to move an unprecedented large number of rural residents to cities over a relative short period of time; i.e., potentially more than 100 million people would move to China’s cities by 2020 potentially leading to large increases in energy consumption and CO₂ emissions. By applying environmentally extended input–output analysis, in this study we estimate the carbon footprint of Chinese urban and rural residents and assess the carbon implications of China’s urban migration plan. Our results show that more than 1 gigaton cumulative additional CO₂ emissions would be induced by moving 100 million rural residents to cities by 2020. Rural–urban migration plans of such scale need to go hand in hand with urban planning and climate policies to mitigate the effects on CO₂ emissions and other environmental issues.

Water is a unique and limited resource. An ample supply of good quality water is a concern, and the potential for water shortages exist. Such shortages of good quality water are real and would likely have significant impacts on the economy and the environment. In the USA, the public expects water management science and technology to be incorporated into effective polices to help minimize or offset adverse impacts on water. Such integration takes time and challenges exist. Challenges to such integration include the need to educate decision makers, lack of needed incentives, limited benefit quantification methods, uncertainty in measurement or estimation of technology performance, the need for comprehensive guiding principles such as sustainability, and lack of broad-scale application of techniques such as adaptive management and environmental management systems. There is a compelling need to continuously make advances in the water management science and technology arena to meet these challenges; however, there is a commensurate need to educate decision makers and stakeholders about the potential benefits derived by the application of such advances. Such educational efforts are needed to better integrate science, technology and water policy in order to make better use of available water.

Sustainable food production for a rapidly growing global population is a major challenge of this century. In order to meet the demand for food production, an additional land area of 2.7–4.9 Mha year⁻¹ will be required for agriculture. However, one-third of arable lands are already contaminated; therefore, the use of polluted lands will have to feature highly in modern agriculture. The use of such lands comes, however, with additional challenges, and suitable agrotechnological interventions are essential for ensuring the safety and sustainability of relevant production system. There are also other issues to consider, such as cost–benefit analysis, the possible entry of pollutants into the phytoproducts, certification and marketing of such products, in order to achieve the large-scale exploitation of polluted lands. The present article addresses the sustainability challenges of crop production from polluted lands and briefly outlines the plausible strategies for using polluted lands for sustainable agricultural extensification.