Less frequent, more intense rain. The most detailed climate projections over Italy are available

Rainy day in Italian city
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Extreme weather events such as heat waves and heavy rainfall are increasing, with a strong impact on humans and the environment. VHR-PRO_IT is an open access climate projection over Italy, with the highest spatial and temporal resolution currently available, and is openly available through CMCC’s Data Delivery System.

In recent years, Italy – along with other Mediterranean and European countries – has witnessed a noticeable rise in extreme weather events, including heavy rainfall and increasing temperatures.

These events have resulted in significant impacts, including floods, droughts, and heatwaves, affecting both people and goods.

According to the CMCC Report on climate change risk analysis for Italy, Italy experienced a 55% increase in extreme weather events in 2022 compared to the previous year, causing several deaths and damaging the environment and the economy.

Urban centers, which host 56% of the Italian population, are “hot spots” for climate change as they are usually characterized by very high vulnerability and exposure, with a growing presence of impermeable surfaces covered with cement and asphalt and few natural areas made up of soil and vegetation.

The urban environment is warmer than the surrounding rural areas, and the expected intensification of extreme climate phenomena for the decades to come, especially heat waves and intense rainfall, is one of the main amplifiers of climate risk factors in cities, as highlighted by the IPCC.

For these reasons, there is a need for more reliable and detailed information to improve the assessment of climate hazards and risk management.

A paper led by CMCC, in collaboration with CINECA, and published on Scientific Data, introduces an open access hourly climate projection with a spatial resolution of around 2.2 km, covering the geographical area of the Italian peninsula. The VHR-PRO_IT (Very High-Resolution PROjections for ITaly) projection covers a 60-year period, spanning from 1989 to 2050. VHR-PRO_IT is produced within the Highlander project, to create climate projections under the IPCC RCP4.5 and RCP8.5 scenarios.

“These are the first climate projections at such a high spatial resolution ever done for the whole Italian peninsula,” said Marianna Adinolfi, researcher at the CMCC’s Regional Model and Geo-Hydrological Impacts (REMHI) Division, and author of the paper. “This is really a step forward compared to existing climate projections. The other important novelty of this research is that we covered rather long periods of time, with very detailed projections spanning several decades, up to 30 years.”

In this work, researchers evaluated both the robustness and the performance of their results, in terms of temperature and precipitation. They used a dataset publicly available on CMCC’s Data Delivery System (DDS), which collects data for 17 atmospheric variables for both the IPCC climate scenarios considered. The paper then compares the results with the state-of-the-art climate projections, represented by the standard EuroCordex data.

“This work is important because with such a high resolution we can explicitly resolve the convection scheme,” said Adinolfi. “These simulations allow for a better understanding of  expected changes in terms of precipitation intensity and frequency, also producing robust results if compared to the Cordex standard.”

VHR-PRO_IT was originally intended for research purposes in the field of climate studies. For example, it may be included in the ongoing activities to clarify the added value of running climate simulation at the convection-permitting scale.

“This work represents a first set of data at a very high resolution for the Italian territory,” said Mario Raffa, of the CMCC’s REMHI Division, and first author of the paper. “We intend it as a useful first step towards further research, as an input for further impact models. We are looking forward to creating an ensemble of very high resolution climate projections over Italy, in order to clearly represent the uncertainties associated with the projections. This would be really relevant to permit the use of this data by decision makers, but of course we are happy to have completed this first relevant step forward.”

Summer hourly indices over Italy for (a) GRIPHO and (b) VHR-PRO_IT: hourly precipitation intensity (mm/h) events.

Summer hourly indices over Italy for (a) GRIPHO and (b) VHR-PRO_IT: hourly precipitation intensity (mm/h) events. Raffa, M., Adinolfi, M., Reder, A. et al. Very High Resolution Projections over Italy under different CMIP5 IPCC scenarios. Sci Data 10, 238 (2023).


“One of the most evident results from this work is something that we actually expected,” said Adinolfi. “The projections show a decrease in the frequency of hourly precipitation events, and an increase in their intensity in the majority of the Italian territory. According to our results, in Italy it will rain less often, but more heavily.”


More information: watch the CMCC webinar “Enhancing the understanding of Italy’s climate: current conditions and projections”.

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