California drought linked to climate change

A new study has found that global warming is to blame for the conditions that resulted in the state drought.

More specifically, the new paper, which was published in the Proceedings of the “National Academy of Sciences”, concludes that the warming responsible for the record-setting California drought, which has led to extremely warm and dry conditions for the past three years in the state, was caused by humans, reported Ars Technica.

The scientists conducted their analysis using a technique called bootstrapping.

The recently published study was carried out by scientists affiliated with the Department of Environmental Earth System Science and the Woods Institute for Environment at Stanford University. The scientists used various forms of data to perform their research, some of which included: historical statewide data for observed temperature, precipitation, and drought in California; Palmer Hydrological Drought Index (PHDI) and the Palmer drought Severity Index (PDSI) gathered by the National Climatic Data Center; and global climate model simulation from the CMIP (Coupled Model Intercomparison Project).

The investigators carried out their analysis using the boostrapping method. This is an approach that enables statisticians to use the same samples over and over again to improve their approximations of particular effects. For this study, bootstrapping was utilized to compare climate data with measures of populations from diverse time periods to enable the scientists to analyze how population changes are connected with differing climate conditions.

Climate change in California appears to be the result of both human and natural factors.

What the analysis found was that statewide warming in California happens in climate models that don’t only include natural factors, but human ones, as wells. The scientists state that their findings strongly suggest that warming caused by humans (anthropogenic warming) has boosted the probability of simultaneously occurring precipitation and temperature conditions that have historically caused droughts in the state.

The scientists also concluded in their study that sustained global warming will probably lead to situations where every dry period in the future, regardless of whether it is seasonal, annual or multiannual, will come with historically warm conditions.

This new study is only one of many that has analyzed California’s drought and each study seems to be arriving at similar conclusions, which is that the recent drought is notable for causing the state to experience both warm and dry winters simultaneously. However, as for whether or not this is related to human factors, requires continued research. That said, what is pretty clear is that California should expect these climate change conditions to be an ongoing problem.