The true statements regarding the distinction between "detection" and "attribution" of climate change are:
1. Detection means we have observed changes in the climate: This statement is true. Detection refers to the identification and observation of changes in various climatic variables, such as temperature, precipitation patterns, sea level rise, etc.
2. Attribution requires understanding the physical processes in the climate system: This statement is true. Attribution involves determining the causes or factors that contribute to observed changes in the climate. It requires analyzing and understanding the underlying physical processes and mechanisms within the climate system.
3. Attribution is not something we can directly observe: This statement is true. Attribution involves scientific analysis and modeling to determine the contributions of different factors, including natural variability and human activities, to observed climate changes. It is not a direct observation but rather a scientific assessment based on evidence and analysis.
4. Detection is something we can directly observe: This statement is true. Detection of climate change refers to the direct observation and measurement of changes in climate variables and patterns over time. It involves collecting and analyzing observational data from various sources, including temperature records, satellite measurements, and climate models.
5. While we have detected climate change, it is not possible to attribute the change to humans: This statement is false. Attribution studies have provided strong evidence that human activities, particularly the emission of greenhouse gases from burning fossil fuels, are the dominant cause of the observed climate change since the mid-20th century. The Intergovernmental Panel on Climate Change (IPCC) has stated with high confidence that human activities have contributed to the warming of the climate system.
In summary, detection refers to observing changes in the climate, while attribution involves understanding the causes of these changes. It is scientifically established that human activities have played a significant role in the observed climate change.