FOREST LAND USE CHANGE IN THE PHILIPPINES AND CLIMATE CHANGE MITIGATION RODEL D. LASCO and FLORENCIA B. PULHIN Environmental Forestry Programme (ENFOR), College of Forestry and Natural Resources, University of the Philippines (Los Baños), College, 4031 Laguna, Philippines (Received 26 February 1999; accepted in final form 20 July 1999) Abstract. Tropical forests in countries like the Philippines are important sources and sinks of carbon (C). The paper analyzes the contribution of Philippine forests in climate change mitigation. Since the 1500s, deforestation of 20.9 M ha (10 6 ha) of Philippine forests contributed 3.7 Pg (10 15 g) of C to the atmosphere of which 2.6 Pg were released this century. At present, forest land uses store 1091 Tg (10 12 g) of C and sequester 30.5 Tg C/yr while releasing 11.4 Tg C/yr through deforestation and harvesting. In the year 2015, it is expected that the total C storage will decline by 8% (1005 Tg) and total rate of C sequestration will increase by 17% (35.5 Tg/yr). This trend is due to the decline in natural forest area accompanied by an increase in tree plantation area. We have shown that uncertainty in national C estimates still exists because they are readily affected by the source of biomass and C density data. Philippine forests can act as C sink by: conserving existing C sinks, expanding C stocks, and substituting wood products for fossil fuels. Here we analyze the possible implications of the provisions of the Kyoto Protocol to Philippine forests. Finally, we present current research and development efforts on tropical forests and climate change in the Philippines to improve assessments of their role in the nations C budgets. Keywords: C sequestration, C storage, climate change mitigation, forest land-use change, tropical forests 1. Introduction Global warming or the increase of the earth’s atmospheric temperature is one of the most pressing issues today. The surface temperature this century is as warm or warmer than any century since at least 1400 AD (Nicholls et al. 1996). By the year 2100, the average surface temperature is projected to increase by 1 to 3.5 ◦ C while sea level is expected to rise by 15 to 95 cm. Greenhouse gasses (GHGs) such as CO 2 , methane, nitrous oxides and chlorofluorocarbons absorb thermal ra- diation emitted by the earth’s surface. Thus, rising concentration of GHGs in the atmosphere could lead to change in the world’s climate. Among anthropogenic GHGs, CO 2 is the most abundant. Forest ecosystems play an important role in the climate change problem because they can both be sources and sinks of CO 2 (Schimel et al. 1995; Brown et al. 1996). At present, the world’s tropical forests are estimated to be a net source of C (1.6 Pg in 1990) primarily because of deforestation, harvesting and forest degradation. However, Mitigation and Adaptation Strategies for Global Change 5: 81–97, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands.