Kajian Paleoklimatologi dan Perubahan Suhu Global

Abstract

Global climate change is a change of climate patterns and intensity on a global scale as a result of changes in the energy budget components within the earth system and may be caused by both natural and antrophogenic factors. Studies of climate change requires a long data which may be reconstructed by several methods of paleoclimatology including ice cores, tree ring, coral, and pollen methods. Climate reconstruction using Ice core method requires longer data records compared with the tree ring, coral, and pollen method. The complexity of physical and chemical analysis are major constaints in utilizing ice core and coral method. On the other hand, the unven speard of tree on the earth cause limitations to the information obtained from tree ring and pollen method. Among factors consider important to the global climate change include solar constant, properties of earth surface, and atmospheric chemical compositions of greenhouse gases. Radiative forcing is an index defined by the rate of energy change per unit area of the globe as measured at the top of the atmosphere. Global climate change is indicated by increased of global average surface temperature which according to data records has increased by 0.7oC during the last century. A number of literature suggest the temperature rise was due to anthropogenic factors; however, using simplified energy balance model of the earth-atmosphere system reveals that an increase of solar constant by 1% (which may occur during the last century), while holding other factors unchanged, will result in an average global surface temperature increase of 0.6oC which is fairly close to the value obtained from observations. It must be emphasized that climate is an extremely complex system in which various factors interact with each other in some forms of linear and non-linear feedbacks. Analysis of time series data of Jakarta Observatory which cover a period of 1965-2010 shows a slight increase of average temperature and decrease of average rainfall.