The earth we inhabit consists of the natural habitats of ocean, air, and land, and all the ecosystems they nurture interact to shape the global environment. For thousands of years the earth’s environment has conferred tremendous benefit to all life and also protected and fostered human existence and civilization. However, in recent years the drastic environmental changes stemming from human activity, including global warming, have appeared. It has become a significant and urgent problem for the world to examine the specific conditions, investigate their causes, and forecast future developments.
The science of environmental change is a field that aims to monitor the oceans, air, land, and ecosystems, using a wide variety of techniques to define prevailing conditions, understand the mechanisms of change, and then develop forecasting models that combine the findings with the expertise to better predict future changes. We also cooperate with institutions both at home and abroad. Through promotion of international earth observation programs, such as the Global Earth Observation System of Systems (GEOSS), as well as our active participation in the United Nations Intergovernmental Panel on Climate Change (IPCC), we contribute to decision-making on climate change solutions and the enhancement of the earth’s sustainability on a global and human scale, while securing Japan’s presence in the arena of environmental change.

• Research Institute for Global Change (RIGC)

The oceans store a large amount of heat and dissolved chemical substances. Their circulation in the oceans has a large impact on the global climate. The purpose of this research program is to elucidate the distribution and temporal changes in heat and chemical materials such as carbon dioxide in the oceans. For this purpose we deploy Argo floats, which drift in the mid-layer of the ocean and surface periodically, to measure and automatically transmit oceanographic data. We also conduct highly accurate basin-scale repeat hydrography using research vessels and mooring buoys, to measure heat flux between atmosphere and ocean in the Kuroshio Extension region. Research is also in progress on a data assimilation technique that integrates these observational data with the results of numerical simulations.

In the tropical Pacific and Indian Oceans, unique and obvious atmosphere-ocean coupled phenomena with various timescale are observed. In particular, the El Nino, the Indian Ocean dipole mode phenomenon, the monsoons, and the Madden-Julian Oscillation - the major tropical ocean/atmosphere variations - are all mutually interrelated, and have great impact on global weather and short term climate change, hence affect human life and economic activities. This Program studies the interaction of these phenomena and their interactions and contributes to the improvement of their predictability. Specifically, the Program aims to reveal the mechanisms of fluctuation in El Nino and the dipole mode phenomenon based on an observation network of moored buoys. In the Western Pacific and Indian Ocean, including the Indonesian and Indochina regions, the Program aims to construct high-precision observation networks of the ocean, atmosphere and land, and to reveal the water cycling mechanism related to the monsoons, from diurnal to annual variability, as well as the mechanism of the Madden-Julian Oscillation and its effects.

The Arctic and Siberia are said to be the regions on earth where global warming will occur most strongly. It is indispensable to clarify the variations and processes responsible for phenomena such as the Arctic Ocean ice change, permafrost melting, and snow cover/glacier change, in order to understand and predict global warming and climate variation. This program will be composed of four parts. Integrated observations of Arctic Ocean using the Mirai cruise ship and icebreakers, and moor buoys in the Arctic to clarify the changes and interactions between atmosphere/sea and ice/ocean. Snow/ice observations and hydrological observation of parts of the Asian Continent such as Siberia, Mongolia and high mountains will be made to advance our understanding of cryosphere variations and the hydrological cycle. Lastly the influence of cryosphere change on abnormal meteorological phenomena and global climate systems will be made to evaluate the regional/global effect.

Materials such as greenhouse gases, including carbon dioxide, circulate through the atmosphere, ocean, and land, with ecosystems playing an important role in this biogeochemical cycle. The increase in atmospheric carbon dioxide from human activity may not only accelerate warming but also alter ecosystem functioning, in turn affecting the biogeochemical cycle which drives up carbon dioxide levels. To secure the future of human life on this planet, accurate prediction of the future climate is indispensable, which requires deepening our understanding of the still unknown feedback mechanisms of ecosystems in the biogeochemical cycle.
The goals of this program are to observe changing ecosystems and biogeochemical cycles in marine and terrestrial environments, to understand the mechanisms of those changes from the past to the present, and to improve the capacity of earth system models for future prediction.

This program investigates the projection of global change by developing an integrated earth system model that includes explicit representations of biogeochemistry, such as carbon-cycle feedback among ocean, air, and land, and interactions between aerosols and atmospheric chemistry. The model is further improved by evaluating its performance against observational data. This program also studies mechanisms of climate change and variation, using paleoclimate simulations and analyses of observed and simulated data to clarify how global change, especially global warming, proceeds in a climate system that fluctuates naturally in various space and time scales, even without changes in external forcing.

Our everyday life and socio-economic activities are strongly affected by natural variability in the ocean and atmosphere, such as short-term climate variations, including El Nino and Indian Ocean Dipole events, significant seasonal variability associated with the Asian monsoon, and variations of the Kuroshio Current south of Japan. We explore mechanisms of such climate and ocean variability over time periods ranging from months to years, and conduct experimental predictions, using numerical models with various complexities, to improve prediction skills of the variations. Validation of the predicted results and feedbacks therefrom are our fundamental and key approach to accomplish the objectives. Basic research on how to apply the predicted results to the societal benefit is also our important research theme.

Considerable uncertainty still exists in weather forecasting and the prediction of climate change. Because of the limitations of current computer performance, it remains difficult to bring about substantial improvements in accuracy. On the other hand, computer performance can be expected to continually improve in the future. The aim of this program is to contribute to the prediction of global climate change over the middle and long term. To achieve this, we are developing extremely precise numerical models which will be able to run on future computers that will emerge over the next five to ten years. We are focusing on the accurate simulation of important processes found in the atmosphere, ocean, and on land.