June 28. () –
Global warming is expected to increase the intensity and frequency of droughts in various regions of the world in the near future, depleting water resources, agriculture and energy.
For a climate change strategy to be successful, it is crucial to understand how the impacts of global warming may evolve over time. A new study led by Japan’s National Institute for Environmental Studies (NIES) presents future periods when aberrant drought conditions will become more frequent, thus creating a new normal. Their findings are published in Nature Communications.
Since current water management practices and existing infrastructures in these sectors are based on statistics or historical experiences, under a changing climate these practices and infrastructures may become insufficient. Therefore, it is critical to better understand when severe drought conditions expressed as “unprecedented” will be prevalent.
“In terms of precipitation and temperature, previous studies report the moment when the impact of climate change arises. However, no study has been able to estimate the moment when the drought will occur by focusing on the discharge of rivers on a scale Tokuta Yokohata, a co-author and principal investigator in the Earth System Hazard Analysis Section in the NIES Earth System Division, explains. adopt appropriate climate change strategies, especially for climate adaptations, long-term and over time”.
The work estimates the periods in which drought conditions will go to an unprecedented state in a warmer world. The research group evaluated changes in the frequency of dry days in 59 subcontinental regions of the world up to the end of the 21st century.
They estimated the time of first occurrence (TFE) of the unprecedented consecutive drought, which is the first start of exceeding the maximum limit of historical climatic variability during the reference period (1865-2005) that occurs consecutively during a given period. number of years. For example, the TFE5 indicates that the frequency of regional drought remains greater than the maximum value during the reference period of 141 years for more than five years.
The scientists analyzed their river discharge simulation dataset, derived from combinations of five global hydrological models and four climate model projections. The study considered scenarios of low and high concentration of greenhouse gases to assess the consequences of society’s decisions in the path of climate mitigation.
“The projected impacts of warming show significant regional disparities in their intensity and rate of growth over time,” says corresponding lead author Yusuke Satoh, a research associate professor at the Korea Advanced Institute of Science and Technology. By mid-century, increases in drought frequency are statistically significant over 25% and 28% of the global land area under the low and high greenhouse gas concentration scenarios, respectively.
Some specific regions show substantial increases of more than double the current frequency. In both scenarios, the so-called hot spots of increased drought include the Mediterranean regions, southern and central South America, Australia, etc. “Some regions show steady increases in the frequency of droughts,” he adds. The projected increases are very likely in the middle of this century compared to the historical period“.
This new study considers consecutive exceedances of more than five years and detects TFE5 in 18 of 59 regions by the end of this century in a scenario of high concentration of greenhouse gases. Even under a low greenhouse gas concentration scenario assuming stringent mitigation strategies, 11 regions are projected to reach GFR5 over the course of the century.
“Under the high and low greenhouse gas concentration scenarios, respectively, seven and five regions show the TFE5 in about 30 years, which is before or around an expected climate stabilization in the case of the low climate change scenario. Importantly, the results imply unprecedented states unavoidable in these regions.“, says Hideo Shiogama, co-author and head of the NIES Earth System Risk Analysis Section.
In particular, southwestern South America and the Mediterranean regions consistently show early and robust EFR5 in both scenarios. On the other hand, the differences between the greenhouse gas concentration scenarios indicate that our choice of mitigation strategies makes a noticeable difference in the timing and robustness of the projection.
“Appropriate and feasible climate mitigation and adaptation plans are essential to overcome the extraordinarily severe drought conditions that are expected. Especially in regards to adaptation, it is crucial to improve our preparedness in the given time horizon before unprecedented drought conditions emergeSatoh concludes.
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