A new study shows that the present day California drought, which has entered its forth year, cannot be fully explained by taking into account only the low precipitation issue. Stanford scientists found that warm temperatures triggered by global warming are also a major contributing factor.
According to the new research, global warming is indirectly fueling California drought by overlapping warm and dry periods, a trend which may accelerate over the next decades.
Scientists argued that greenhouse gas emissions make the planet increasingly warmer at ground and sea surface levels thus amplifying the effects of low precipitation through evaporation. Even if normal precipitation would occur, global warming will make water supply evaporate at a faster rate.
The key for drought stress is not just how much precipitation there is. Temperature is an important influence on the water available in California,”
explained Noah Diffenbaugh, lead author of the study and professor at Stanford University’s School of Earth, Energy and Environmental Sciences.
Scientists also said that high temperatures triggered by anthropic climate change also lower the moisture in soils, fuel evaporation of ground water supplies and make California drought worse.
During their study, Prof. Diffenbaugh and his colleagues sifted through the historical records on California droughts over the last and present centuries. They learned that over the last couple of decades the overlapping of warm and dry years has more than doubled, as compared to the preceding decades.
Additionally, the team believes that the situation is set to only get worse if man doesn’t do anything to stop the actual climate change trend. Scientists said that we should also expect California-like droughts occurring in other states, too.
Study authors underlined that the modern-day droughts cannot be fully understood by omitting the role of warmer temperatures, which are a “critical contributor to drought risk.”
Their study findings were published March 2 in the journal Proceedings of the National Academy of Sciences.
However, other studies contradict the theory that climate change is a major factor behind the California drought. Last fall, a paper published by the Bulletin of the American Meteorological Society showed that the link was debatable.
That paper was issued by 20 separate teams that had assessed the role of climate change in more than 15 extreme weather events experienced by our planet two years ago. Back then, Prof. Diffenbaugh maintained his position and wrote that the high-pressure storms occurring north of the state were linked to global warming. But the other teams argued that the California drought was attributed to “natural variability.”
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