how human activities affect climate system?
 The human causes of climate change are some of the most important concepts to teach. Human activities, particularly the combustion of fossil fuels, are altering the climate system. Human-driven changes in land use and land cover such as deforestation, urbanization, and shifts in vegetation patterns also alter the climate, resulting in changes to the reflectivity of the Earth surface, emissions from burning forests, urban heat island effects and changes in the natural water cycle. 