The Climate Shift Index (CSI) reveals how much climate change influences the temperature on a particular day. The index ranges from -5 to +5 with positive levels indicating temperatures that are becoming more likely due to climate change (negative scores indicate conditions that are becoming less likely). For levels at 2 or above, the Index is a multiple of how frequently a particular temperature will occur due to climate change. For example, a CSI of level 5 means that a temperature is occurring 5 times more frequently when compared to a world without human-caused carbon pollution. This temperature would be very difficult to encounter in a world without climate change–not necessarily impossible, just highly unlikely.