a tree or its lumber burns or decays, but as long as the forest is able to grow back at the same rate as its biomass is lost due to oxidation of organic carbon, the net result is carbon neutral.) In their 2001 assessment, the IPCC estimated the potential of biological mitigation options (mainly tree planting) is on the order of 100 Gigatonnes of carbon (cumulative) by 2050, equivalent to about 10% to 20% of projected fossil fuel emissions during that period. However, the global cooling effect of forests from carbon sequestration is not the only factor to be considered. For example, the planting of new forests may initially release some of the area's existing carbon stores into the atmosphere. For example, if one included emissions from the conversion of peat bogs into oil palm plantations in national GHG totals, this would move Indonesia from 21st to third place as the world's largest producer of greenhouse gases. Compared to less vegetated lands, forests affect climate in three main ways: Cooling the Earth by functioning as carbon sinks, and adding water vapor to the atmosphere and thereby increasing cloudiness. Warming the Earth by absorbing a high percentage of sunlight due to the low reflectivity of a forest's dark surfaces. This warming effect, or reduced albedo, is large where evergreen forests, which have very low reflectivity, shade snow cover, which is highly reflective. To date, most tree planting offsets strategies have taken only the first effect into account. A study published in December 2005 combined all these effects and found that tropical forestation has a large net cooling effect, because of increased cloudiness and because of high tropical growth and carbon sequestration rates. Trees grow three times faster in the tropics than in temperate zones; each tree in the rainy tropics removes about 22 kilograms (50 pounds) of carbon dioxide from the atmosphere each year. However, this study found little to no net global cooling from tree planting in temperate climates, where warming due to sunlight absorption by trees counteracts the global cooling effect of carbon sequestration. Furthermore, this study confirmed earlier findings that reforestation of colder regions—where long periods of snow cover, evergreen trees, and slow sequestration rates prevail—probably results in global warming. According to Ken Caldeira, a study co-author from the Carnegie Institution for Science, "To plant forests outside of the tropics to mitigate climate change is a waste of