U.S. Climate Shift Index ™ Map
Learn more about the Climate Shift Index ™ or refer to our technical documentation.
Receive free, timely email alerts whenever climate-relevant events occur locally.
What's the CSI scale?
The CSI is a categorical scale, with the categories defined by the ratio of how common (or likely) a temperature is in today's altered climate vs. how common it would be in a climate without human-caused climate change. For the positive CSI conditions (which occur much more often than the negative), we assigned a simple descriptor to these events (see table).
Descriptor | CSI level | Interpretation | CSI level | Interpretation |
|---|---|---|---|---|
No effect | 0 | The influence of climate change on the conditions (i.e. the daily high or low temperature) is not detectable. These conditions could occur about as often with or without climate change. | 0 | The influence of climate change on the conditions (i.e. the daily high or low temperature) is not detectable. These conditions could occur about as often with or without climate change. |
Moderate | 1 | Climate change made the conditions at least 1.5 times more likely. A CSI level of 1 indicates a detectable climate influence. | -1 | Climate change made the conditions at least 1.5 times less likely. |
Strong | 2 | Climate change made the conditions at least twice as common. CSI levels of 2 and higher indicate a dominant climate influence. | -2 | Climate change made the conditions at least 2x less common. |
Very strong | 3 | Climate change made the conditions at least 3x more likely | -3 | Climate change made the conditions at least 3x less likely |
Extreme | 4 | Climate change made the conditions at least 4x more common. These conditions would be extremely rare without climate change. | -4 | Climate change made the conditions at least 4x less common. These conditions are becoming extremely rare with climate change. |
Exceptional | 5 | Climate change made the conditions at least 5x more likely, potentially far more. This is an exceptional event driven by climate change. | -5 | Climate change made the conditions more than 5x less likely. These conditions are becoming exceptionally rare with climate change. |