Many natural systems are being affected by climate variation and climate changes, particularly in respect of temperature increases. Current scientific evidence indicates that global warming is progressing due to an increase in anthropogenic (i.e. man-made) greenhouse gas emissions mostly due to industrial activity. However, uncertainties in the projection of future climate change remain—also due to the ambiguity of our social and economic systems. Although there are variations seen in the extent and scope of impacts of climate change, as well as regional (i.e. geographical) variations, the net annual costs of climate change are expected to increase over time as global warming continues (IPCC 2007: 8-9, 17, 20; Hilpert et al. 2007: 9). According to the Intergovernmental Panel on Climate Change (IPCC):
a portfolio of adaptation and mitigation measures can diminish the risks associated with climate change (IPCC 2007: 20).