The elements of climate change are many and varied, but can be broadly divided into three main categories: physical, chemical, and biological.
Physical factors include changes in the amount of sunlight received by the Earth, changes in the Earth's orbit, changes in the Earth's albedo (reflectivity), and changes in the Earth's greenhouse gas composition.
Chemical factors include changes in the concentrations of greenhouse gases and other atmospheric constituents.
Biological factors include changes in the composition of terrestrial and aquatic ecosystems, and the distribution and abundance of plants and animals.