Climate outlook

Climate outlook#

Hydro-meteorological hazards are affected by climate forcing, and, as such, climate change should be accounted when estimating future risk conditions. A forward-looking analysis makes use of climate projections to explore how environmental risks could develop spatially over time.

The long-term averages of climate indices (observed or simulated) serve as the baseline conditions, against which the effects of climate change are measured for future scenarios. Changes in projected climate indices against this baseline (anomalies) and used to estimate changes in natural hazard frequency and intensity.

Table 1 Climate variables underlying hazard projections#
Hazard	Associated climate indices	Unit of measurement
Floods and Landslides	Rainfall > 10 mm	Days per year
Floods and Landslides	Consecutive wet days	Days per year
Floods and Landslides	Maximum 5-day precipitation	mm
Floods and Landslides	Extremely wet days	mm
Coastal floods	Sea Level Rise	m
Drought	Annual SPEI	[-]
Drought	Consecutive dry days	Days per year
Heat stress	Heat index (WBGT or UTCI) for moderate or extreme stress	Days per year

Given that specific unit of measurement varies across climate indices, in order to give a comparable metric of change the projected anomalies against the baseline are expressed in terms of Standard Deviation (SD) of the anomaly compared to historical variability E3CI, 2020. Data from climate models released under the IPCC Sixth Assessment Report (AR) framework are used to establish estimates of baseline and future projected climate anomalies. ARs are supported by coordinated climate modeling efforts referred to as Coupled Model Intercomparison Projects (CMIP).

The analysis relies on CMIP6 data for modeling into the future, and takes into account four climate change scenarios, referred to as Shared Socioeconomic Pathways (SSPs) in CMIP6. These pathways cover the range of possible future scenarios of anthropogenic drivers of climate change by accounting for various future greenhouse gas emission trajectories, as well as a specific focus on carbon dioxide (CO2) concentration trajectories (IPCC 2021b).

Guidance for aligned scenario selection is provided by the shared CCDR Global Climate Scenarios note.

../_images/climate_scenarios.png — Fig. 8 Recommended CCDR Global Scenarios and characteristics for adaptation and development planning.#

SSP1-1.9 / RCP2.6: emissions peak between 2040 and 2060, declining by 2100. This results in warming of 3-3.5 °C by 2100.
SSP2-4.5 / RCP4.5: emissions continue to increase through the end of the century, with resulting warming of 3.8-4.2 °C by 2100.
SSP3-7.0 / RCP8.5: models describe a large emission variability for this scenario. Warming is estimated at 3.9-4.6 °C by 2100.

Each climate scenarios predicts different spatial patterns, resulting into a range of possible futures in terms of intensities, and frequencies of natural hazards. Key climate variables connected to the changing patterns of precipitation and temperature are collected from the Climate Change Knowledge Portal and the Copernicus Data Store.