Monsoon Asia is a region of Asia that comprises over half the world’s population, consisting of 20 countries in South, Southeast and East Asia. This area is controlled by monsoon climate which is of crucial importance to Asia mainly because it brings the water that supports human life, plants and animals. In the past decades, this region has experienced one of the most rapid changes and is likely to undergo further rapid development in the coming years. Land-cover and land-use changes (LCLUC) in Monsoon Asia are being powered by demand for food for its growing population, a large demand for bioenergy for its economic development and by the transition from a largely rural society to one in which more than half of its people are expected to live in cities within two decades. People want to use land for energy, to live and for food, so all are competing for land. There is a rapidly increasing concern that land cover and land use changes are expected to have significant impact on the variability and intensity of the Asian monsoon and further influence the provision of goods and services by terrestrial ecosystems in the region. The goals of this project are to understand complex interactions among land use, ecosystem and climate and to evaluate the impacts of current and projected LCLUC on climate, water and carbon cycling in the region of Monsoon Asia in the first half of 21st century. Our strategy to pursue our goals involves the following major objectives: 1) We will develop and use an Integrated Regional Earth System Model (IRESM) that will include an enhanced dynamic land ecosystem model (DLEM), a newly developed regional climate model, an extant economic model, and an improved land use model. 2) We will evaluate and validate IRESM against ground and satellite observations. 3) In support of this work, we will develop and refine a 30 km gridded dataset for Monsoon Asia by using a combination of ground- and satellite-based observations. This dataset will include information on LCLUC, climate, chemistry of the atmosphere and precipitation, and fires. 4) We will assess regional fluxes of carbon and water across monsoon Asia in the 20th century, and understand the mechanisms that affect these fluxes. 5) We will assess to what extent LCLUC has modulated and will modulate the Asia monsoon climate in the past and future, and how the changed monsoon climate will influence LCLUC in this region in the first half of 21st century. 6) We will propagate and calculate the sensitivities of the IRESM to major inputs and model parameters, and use those sensitivities to quantify uncertainties in the system results. This research will be done in a fully collaborative fashion with a team of scientists from both US institutions and Asian countries in the region. Together, we will develop the input databases, conduct model simulations, and evaluate the results. Our preliminary analysis indicates that there has been a dramatic land transformation across the region in the past 300 years. Cropland and urban areas increased by 288% and 243% respectively, while forest and grassland areas decreased by 23% and 10% respectively. As estimated by the dynamic land ecosystem model (DLEM), LCLUC has resulted in a large amount of carbon release from terrestrial ecosystems to the atmosphere (See figure) and led to a large reduction of water yield over the region during 1700- 2005. Our simulated results indicate that LCLUC-induced changes in both carbon storage and water yield show substantial spatial variation across the region. Most of these changes have occurred since the beginning of the 20th century.