In this article, the phrase "global warming" refers to the change in the Earth's global average surface temperature. Measurements show a global temperature increase of 1.4 °F (0.78 °C) between the years 1900 and 2005. Global warming is closely associated with a broad spectrum of other climate changes, such as increases in the frequency of intense rainfall, decreases in snow cover and sea ice, more frequent and intense heat waves, rising sea levels, and widespread ocean acidification. The Intergovernmental Panel on Climate Change (IPCC) has produced several reports where the economics literature on climate change is assessed. In 1995, the IPCC produced its second set of assessment reports on climate change. Working Group III of the IPCC produced a report on the "Economic and Social Dimensions of Climate Change." In the later third and fourth IPCC assessments, published in 2001 and 2007 respectively, the assessment of the economics literature is divided across two reports produced by IPCC Working Groups II and III. In 2011 IPCC Working Group III published a Special Report on Renewable Energy Sources and Climate Change Mitigation. The changing elements of climate change have two consequences. Fist a scarcity of resources like food, water, and agricultural land. Second an increase of the number of natural disasters like floods, storms, and tropical cyclones. These consequences lead to three social effects: political instability, economic instability, and migration.