Study identifies increased frequency of connected schemes, from drought to heavy rain in regional hotspots
Like a wavy swing, time in certain regions fluctuates drought heavy rains under the weight of climate change, according to an analysis published in Geophysical research letters. The study finds a link between droughts followed by heavy rain, as well as an increase in the rate of these extreme weather events.
In areas with vulnerable populations and high poverty rates, these fluctuations risk worsening conditions. This research could inform more effective climate adaptation planning and policies by identifying where these fluctuations are likely to occur.
“Extremely dry and humid conditions are increasingly making the headlines in the world. However, existing studies generally treat them separately,” said study lead author Xiaogang He, who led the work. at Princeton University as a doctorate. a student and now a postdoctoral fellow in the Water in the West program at Stanford University. “Their consecutive occurrence, especially in the same place over a short period, amplifies the impact on local populations and therefore deserves more attention.”
To examine this relationship, the researchers developed a framework for identifying and examining long-term and large-scale historic dry and humid periods. By examining global precipitation and soil moisture data from 1950 to 2016, they detected episodes of drought and heavy precipitation on a regional scale. Then they created a statistical model to identify if there was a relationship between these two types of extreme events over the seasons.
They found that in the past seven decades, about 11% of the world’s droughts have been followed by at least one heavy rain event in the next three months in a concentrated area or region. In particular, the Democratic Republic of the Congo, Kenya, Brazil, Canada, Botswana, Iran, China and Myanmar had an average tilt occurrence of more than 25% during the study period , revealing a continuing trend of these harsh weather events related to certain locations.
The team also identified regional “rocking” hotspots – mainly in mid-latitude regions – which experienced an increase in the frequency of droughts with correlative rains that followed during the next season. These hotspots, which include Asia, Southern Africa and Oceania, have high poverty rates and populations more vulnerable to extreme weather conditions.
“We know something about the individual risk of drought and very wet events, but very little about how they combine,” said lead author Justin Sheffield, a professor of hydrology and remote sensing at the University. from Southampton. “This research is the first to examine this situation on a global scale, to identify the level of real risk and where it could increase.”
These extreme events often wreak havoc on agriculture, food and water security, energy production, infrastructure and ecosystems. Identify areas likely to have an increased frequency of drought and heavy rain, as well as the swing between the two, is important for disaster preparedness and can help aid organizations to prioritize the allocation of resources such as food, water, shelter or medical supplies.
As global warming increases the likelihood of extreme droughts and precipitation in the future, human activity, such as increased water consumption, changes in land use, urbanization and agriculture, could also force faster and more violent transitions between flip-flop events, the study found.
The researchers also point out that the United States is not immune to dramatic swings from dry to wet weather, citing the 2017 wet conditions in California that contributed to widespread flooding after a drought of several years. Thousands of people across the state were forced to evacuate, while floods drowned crops, created landslides and caused more than $ 1 billion in damage to roads and highways.
A crucial question they plan to study next is whether the increased frequency of these extreme weather conditions is due to climate change, which could signal the possibility of further extreme weather changes in the future.
Xiaogang He et al. Delayed compound occurrence of droughts and rainfalls worldwide over the past seven decades, Geophysical research letters (2020). DOI: 10.1029 / 2020GL087924
Increase in the frequency of connected schemes, from drought to heavy rain in regional hotspots (2020, May 15)
retrieved May 15, 2020
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