In the memorable first year of Reiwa, which was the 30th anniversary of the establishment of the Japanese Association for Arid Land Studies, we planned a symposium to reconsider how to deal with desertification. As the keynote speech, the author gave a review on 1) the definition of desertification, 2) the outline and current status of the United Nations Convention to Combat Desertification, and 3) the current status of desertification. 1) The definition of desertification was completed Agenda 21 in the United Nations Coference on Environment and Development held in Rio de Janeiro, Brazil in 1992, and is used as it is in the Convention to Combat Desertification. It is said that desertification occurs as a result of the decrease in productivity and complex systems of each ecosystem due to the accumulation of desertification processes caused by climatic and human activity factors. Desertification processes such as erosion themselves are direct results, at the same time, it can be said to be a factor of desertification. 2) The outline and organization of the United Nations Convention to Combat Desertification, which came into effect in 1996, and the history of the Conference of the Parties were introduced. Based on the United Nations Sustainable Development Goals (SDGs) as recent major movements of the treaty, two major concepts; land degradation neutrality (LDN) and sustainable land management (SLM) were introduced, and “Global Land Outlook” was issued. 3) As for the current state of desertification, there are not many conclusive estimates recently compared with 60,000 km²/year, which was once well used. The 3rd edition of the World Desertification Map published in 2018 evaluates desertification from various factors including socio-economic factors, suggesting that it is difficult to capture the desertification phenomenon. On the other hand, the author also introduced a report that greening is progressing mainly in China and India. Is desertification progressing? Both of pros and cons were mentioned to this question. Desertification and treat with desertification are one of the main points of the activities of this society, so the Commission of Agriculture Development for Arid Lands will continue to follow up. A constant implementation is required to deal with desertification. In order to maintain Japan’s presence, it is necessary to maintain the base of arid land research and desertification coping research, especially to promote research including industry, academia and government on desertification coping and to promote international cooperation.

The fulvic acid used for the vegetable activator, cosmetic raw materials and so on is the useful organic acid contained in a Japanese forested soil but only the minute quantity is contained all over the ground, and there are details to have imported a mined limited resource from the foreign countries to use for these uses and to used it in the country. Because it succeeded in the produced ligneous material of to Japanese thinning from a forest and condensation of the organic matter of to using the organic acid produced with a production sequence such as the charcoal and prompt of polymerizing in such a situation, it became possible to make a fulvic acid with a high purity artificially in quantities. Because it succeeded in the produced ligneous material of to Japanese thinning from a forest and condensation of the organic matter of to using the organic acid produced with a production sequence such as the charcoal and prompt of polymerizing in such a situation, it became possible to make a fulvic acid with a high purity artificially in quantities.

For greening the desert, fresh water cost is required to be less than 50 ¥/m³ or less at the plantation site from the view point of economical productivity of greening. Under the condition of water transportation/distribution cost of 20-30 ¥/m³, desalination cost should be less than 30-20 ¥/m³. Furthermore, the energy sources and the cost of the electric power should be qualified for the production, transportation, and distribution of the huge amount of produced fresh water together with the treatment of salt-concentrated water.

In conclusion, the energy sources and cost for water production from deep seawater are qualified and reduced by the following system: Combination of rough NF/rough RO/TC is introduced and the concentrated water is used for salt production. Low-temperature solar-thermal-energy conversion is used as a stable, safe, low-cost, and environment-friendly power-generation system.

As a possible future energy-saving system, the absorption heat pump one is also proposed, although it is under the conceptual design level, at present.

In 2020, the increase in the number of infected people due to the new coronavirus infection (COVID-19) pandemic and the stagnation of economic and social activities due to lockdown, etc. The economy as a whole, including industry and finance, is expected to stagnate and cool more than the Lehman shock in 2008. In addition to the recovery from ongoing economic crisis, the voices calling for green recovery to tackle the long-standing climate crisis and the social disparity highlighted by COVID-19 are resonating anywhere in the world including Japan. Renewable energy, especially agrivoltaic, which is the subject of this paper, is expected to be the center of such measures.