Two of the most tangible effects of climate change are worsening heat waves and worsening droughts. A new study found that these two hazards are occurring concurrently with startling frequency in recent years, a combination that will put enormous strain on regions already facing long-term worries over dangers like wildfires and dwindling resources.
Researchers studied data covering the period between 1896 and 2017 and found that concurrent extreme heat waves and extreme droughts—called “dry-hot extremes”—are on the rise across the United States. It used to be relatively rare for these two high-impact events to overlap with one another.
The western half of the country saw a significant rise in dry-hot extremes during the 122-year period, with an increased frequency also noted along the I-95 corridor in the Mid-Atlantic and Northeast, as well as the Florida peninsula. Just between 2011 and 2013, the study points out, the United States experienced three dry-hot extreme events that resulted in $60 billion in damage.
The study also found that the main driver of dry-hot extremes is shifting from drought to extreme heat.
We’ve long known that heat and drought feed off of one another through a feedback cycle. Water vapor evaporating out of moist soil and healthy vegetation keeps air temperatures cooler due to water’s high heat capacity. Arid soil and desiccated vegetation, on the other hand, allows intense sunshine to heat the ground more efficiently, which then heats the air above.
This feedback cycle results in a situation where drought worsens heat, reinforcing the drought in turn. Now, according to the researchers, extreme heat is the driving force that leads to the one-two punch of intense heat waves occurring alongside intense droughts. Rising global temperatures and more frequent heat waves will lead to more opportunities for dry-hot extremes to occur in the United States.
An increase in the frequency of concurrent heat waves and droughts could make devastating wildfire seasons more common in the years to come. Hot temperatures, dry air, and dry vegetation allow fires to spark and spread with ease, quickly becoming raging infernos that are difficult to contain before they consume thousands of acres.
These combined hazards could also strain water resources in regions that are already struggling with high demand. Extended heat waves and extended droughts will further deplete natural water sources through increased evaporation and increased demand.
This new research codifies a phenomenon in which millions of residents of the western United States are well-versed.
Folks west of the Rockies have been through the wringer this summer. Phoenix recorded an astounding 53 days this year with high temperatures that reached or…