“No evidence is found for any systematic trend in precipitation deficits attributable to anthropogenic climate change.” – O’Connell et al., 2022
In a new study (O’Connell et al., 2022), scientists use a stochastic or random probability distribution analysis to assess whether a signal in global precipitation deficits (droughts) could be linked to anthropogenic climate change (ACC) over the 1900-2013 period.
The exhaustive analysis revealed no or pattern that could be statistically validated to support claims that global precipitation deficits are linked to ACC. Instead, no clear trend has emerged that falls outside the range natural variability.
In fact, the authors found that there was globally more intensive precipitation deficits observed from 1901-1938 (Period 1), when CO2 levels were lingering in the 300-310 ppm range, than since the late 1970s when CO2 rose to over 400 ppm. The most recent decades are observed to be associated with the lowest precipitation deficit intensification.
This is actually the opposite trend direction if ACC and rising CO2 were indeed a driving cause of global drought.
The authors caution climate modelers to avoid leaping to conclusions about a link between ACC and global precipitation without utilizing randomized probability statistical analyses. Failure to do so can bias results in favor of desired outcomes.
There is already a politicized tendency to “start from the premise that ACC is an explanatory factor [for global drought], and set out to prove it” rather than follow the scientific method (i.e., falsify the null hypothesis that natural climate processes are causal using real-world observational data).