During the past several years, the circumstances surrounding aviation sector have changed considerably from the environmental aspects. International aviation sector is included in neither Kyoto Protocol (1997) nor Paris Agreement (2015), although domestic aviation is covered by both. In fact, the international aviation is left to the deliberation at ICAO, a UN specialized agency. In 2010, ICAO has set the global sector targets of 2% annual fuel efficiency improvement through 2050 and carbon-neutral growth from 2020 onward. In 2016, it has agreed on the first-ever global market-based measure for an entire sector, the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). In addition, it agreed in 2022 on the net-zero carbon emission goal by 2050 (Long-term Global Aspirational Goal, LTAG) in support of the Paris Agreement’s temperature goal along with various measures (basket of measures) and set the necessary adjustment to CORSIA from the huge impact of COVID-19. Market-based mechanism is also written in Paris Agreement (Article 6), and by 2023, rules for the market-based mechanism are being formulated, but the process for negotiating details has no yet finished as of April 2024. It might be said that the general perception of air travel has been significantly diversified from traditional safety and efficiency only to emphasize more and more about environment and sustainability just as we can see the terminology of “Flight Shame” in common use. This could be because there have been steadily growing concerns about environmentally negative aspects of aviation congestion at many air travel hubs, social and community levels of adverse effects of over-tourism, and occurrence of more and more severe natural disasters from powerful typhoons or huge wildfires, which many suspect could be caused by climate change stemming from emission of GHGs including from autos or aircrafts. Then came the COVID-19COVID-19, which could fundamentally change the way of traveling, working, and even communicating in the direction of touchless, remote, or virtual relationships. Its imminent effects are overwhelming worldwide, but the medium- or longer-term effects are yet to be seen. We have now common global target and the basket of measures to achieve it in international aviation sector at ICAO. In the domestic aviation sector, which is now covered in Paris Agreement, parties also agreed on the common global target and started constructing details of the measures to achieve the target, such as market-based mechanism. The effective financial and technical aids, for example from developed countries to the developing ones, are ever more important to incentivize and execute the necessary efforts of both sides to actually meet the global target. Because climate crisis is interconnected with biodiversity, the proper cost sharing is ever more important. We are going to shed lights on the incentive design problem between developing countries and developed ones with the framework of the game theoretic analysis under asymmetric information structure focusing on the so-called double moral hazard situation of the two sides. The main results show that it is extremely difficult for both sides to achieve common optimal incentive rules about aid payments under the information asymmetry. The measures to drastically mitigate the cost of efforts, to fundamentally reduce risk-averse parameters, and to equalize damage effects of temperature anomaly between the two sides through scientific researches and long-term education on the matter are the key for such optimal incentive design.