Several mainstream news sources, including The New York Times (NYT) and BBC, claim that a new study shows that recent severe drought conditions in the Amazon rainforest were “fueled” or driven by climate change. The stories are false on two fronts. First, the study in question merely says the drought was made more likely due to climate change, but more pressing, the study does not get into a detailed analysis of the causes of the drought, and real-world data show that severe drought is not becoming more common in the Amazon.
The study is another in a growing number of rapid attribution studies from a group called World Weather Attribution Initiative (WWAI) that finger climate change as the primary driver of extreme weather events. As with past “studies” produced by WWAI, the mainstream media is only too happy to once again promote and even exaggerate what the study claims.
Ryan Maue, a meteorologist and weather researcher, pointed out that the media reporting on this latest attribution study is wildly inconsistent, with some articles like one from the NYT admitting that severe drought still would have occurred even if there was no anthropogenic (human-caused) warming; the BBC explaining that El Niño conditions are a contributing factor, and Financial Times saying that El Niño is NOT a major influence. Maue goes on to say that the most accurate reporting about the study was done by Axios, which reported that El Niño and climate change reduced rainfall by “about the same amount” and “while the El Niño worsened the drought, higher temperatures were the catalyst, and also vaulted it to more severe levels[.]”
This is most accurate description of what the study authors actually claim, but none of the media stories discussing the report address the real problem with it and other attribution studies, which is, these studies are statistical exercises and do not count as proof or evidence that climate change is behind any particular bout of bad weather. They prove nothing.
Climate Realism has frequently described why these kinds of attribution studies are problematic, especially when used by the media as fodder for climate alarm, including here, here, and here, for example. Attribution studies begin with the assumption that climate change is a major cause of the weather events studied by the authors, who do not try to explore other potential causes of drought, nor did this particular analysis take into account the full complexities of the water cycle and feedbacks in the Amazon rainforest.
Unfortunately for the climate attribution artists, several independent kinds of data exist that contradict the idea that climate change is the primary driver of droughts, or causing more extreme droughts, in the Amazon River Basin.
In 2021, a paper was published in the journal Water by Paredes-Trejo et al. “Long-Term Spatiotemporal Variation of Droughts in the Amazon River Basin.” The researchers found that there is no long-term increase in the frequency or severity of drought in the Basin between 1901 and 2018, explaining in the abstract:
A weak basin-wide drying trend was observed, but there was no evidence of a trend in extreme drought events in terms of spatial coverage, intensity, and duration for the period 1901–2018. Nevertheless, a progressive transition to drier-than-normal conditions was evident since the 1970s, coinciding with different patterns of coupling between the El Niño/Southern Oscillation (ENSO) phenomenon and the Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), and Madden–Julian Oscillation (MJO) as well as an increasing incidence of higher-than-normal surface air temperatures over the basin. Furthermore, a high recurrence of short-term drought events with high level of exposure to long-term drought conditions on the sub-basins Ucayali, Japurá-Caquetá, Jari, Jutaí, Marañón, and Xingu was observed in recent years.
In other words, while there does appear to be a general trend towards mildly drier conditions since the 1970s, severe drought isn’t getting worse.
The New York Times admits that deforestation is likely a contributing factor in the drought conditions, explaining, “[d]eforestation of the Amazon, the world’s largest and most biodiverse rainforest, has decreased rainfall and weakened the ability of trees and soil to retain moisture, researchers found.” The NYT doesn’t admit it (the author of the piece was likely unaware the research exists) but the gradual encroachment of deforestation might even be an influential factor in the long term mild drying trend indicated by the 2021 Paredes-Trejo et al. study.
This is particularly likely as a culprit amid the data that show precipitation in the Amazon actually significantly increased between 1979 and 2015, as discussed by Climate Realism here. Deforestation and increased agriculture is likely putting more pressure on the water cycle in the Amazon River Basin than this increase in rainfall can overcome.
As an aside, Al Jazeera recently reported that ancient pictographs have been revealed on rocks that were previously beneath the water line on the north shore of the Amazon river, which, of course, only serves to prove that water levels have been this low in the past, thousands of years of global warming and cooling ago, making the current conditions anything but unprecedented. A similar thing was reported in Europe in 2022, during a drought which revealed “hunger stones” in rivers there, recounting the history of severe drought in Europe. The media, quick to blame the low water levels in Europe on climate change, missed the irony of the point that the stones provided evidence that Europe had experienced similarly severe droughts repeatedly in the past, long before the invention of the internal combustion engine.
Overall, media outlets should take care to examine all the data available before they tout any particular study, especially an attribution study, as speaking authoritatively concerning the causes of any particular weather event or short-term trend. It is no more appropriate for responsible media outlets to cite computer generated attribution results to promote scare-stories about climate change as if they were scientifically grounded facts, than it would be for them to promote the predictions of some sideshow carny fortune teller leering into a crystal ball. Plugging untested assumptions, complex math, and unproven feedback mechanisms into a computer algorithm doesn’t make its outputs or forecasts science. Data provide no evidence the Amazon River Basin is in long term danger from drought, particularly if deforestation is addressed.