This study analyzes climate classification in continental Portugal according to the Köppen-Geiger and Köppen-Trewartha climate classification systems, considering three different CMIP6 future climate scenarios outlined by the Shared Socioeconomic Pathways (SSPs), for two different future periods (2046–2065 and 2081–2100). Results show that in the medium-term (2046–2065), the Köppen-Geiger classification indicates a dominant temperate Mediterranean hot-summer (Csa) climate across Portugal, with some regional variations. Despite scenario differences, climate class patterns are consistent, with shifts driven by temperature rise and changing precipitation. The Köppen-Trewartha classification reveals marked changes, particularly in the Cr (subtropical humid), Cs (subtropical summer-dry), and Do (temperate oceanic) classes. A significant reduction of the Do class suggests overall warming. In the long-term (2081–2100), trends persist, with continued Csa dominance and further decline of colder classes, mainly replaced by Cr. This implies longer warm periods (8–12 months > 10 °C) and less rainfall. Central-northern areas are projected to shift to Cr, while central-southern areas retain the Cs type, reinforcing warming and drying trends. Both classifications indicate future drought and heat intensification, especially in summer. These findings underscore the critical role of climate classification systems in understanding and predicting climate variability and change. Nonetheless, it is evident that the Köppen-Geiger climate system lacks the necessary sensibility for regions like Portugal, mainly in delineating class transitions. Therefore, it is imperative to complement the analysis of smaller regions with the Köppen-Trewartha climate system. Graphical Abstract This graphical abstract summarizes the projected climate changes in continental Portugal according to the Köppen-Geiger and Köppen-Trewartha climate classification systems, based on three future CMIP6 scenarios (SSPs) for two time periods: 2046–2065 and 2081–2100. The color-coded map illustrates the spatial distribution and shifts in dominant climate types across Portugal, with a clear transition from temperate oceanic and subtropical summer-dry climates toward hotter and drier conditions, especially in central and southern regions. The Köppen-Geiger classification shows a growing dominance of the hot-summer Mediterranean climate (Csa), while Köppen-Trewartha reveals a significant expansion of the Cr (humid subtropical) type, reflecting longer warm periods and reduced precipitation. These shifts are more pronounced in the long-term horizon, highlighting a consistent warming and drying trend across the territory. The graphic emphasizes the limitations of Köppen-Geiger in capturing regional nuances, reinforcing the value of Köppen-Trewartha for finer-scale assessments. The visual synthesis underlines the critical importance of accurate climate classification systems to support future planning and adaptation strategies in sectors such as agriculture, urban development, and water management.

Climate Classification Shifts for Future Climate Change in Portugal

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发表日期：

2025年9月29日

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M. Teixeira,
A. Rocha,
Rui Silva,
D. Carvalho

摘要

This study analyzes climate classification in continental Portugal according to the Köppen-Geiger and Köppen-Trewartha climate classification systems, considering three different CMIP6 future climate scenarios outlined by the Shared Socioeconomic Pathways (SSPs), for two different future periods (2046–2065 and 2081–2100). Results show that in the medium-term (2046–2065), the Köppen-Geiger classification indicates a dominant temperate Mediterranean hot-summer (Csa) climate across Portugal, with some regional variations. Despite scenario differences, climate class patterns are consistent, with shifts driven by temperature rise and changing precipitation. The Köppen-Trewartha classification reveals marked changes, particularly in the Cr (subtropical humid), Cs (subtropical summer-dry), and Do (temperate oceanic) classes. A significant reduction of the Do class suggests overall warming. In the long-term (2081–2100), trends persist, with continued Csa dominance and further decline of colder classes, mainly replaced by Cr. This implies longer warm periods (8–12 months > 10 °C) and less rainfall. Central-northern areas are projected to shift to Cr, while central-southern areas retain the Cs type, reinforcing warming and drying trends. Both classifications indicate future drought and heat intensification, especially in summer. These findings underscore the critical role of climate classification systems in understanding and predicting climate variability and change. Nonetheless, it is evident that the Köppen-Geiger climate system lacks the necessary sensibility for regions like Portugal, mainly in delineating class transitions. Therefore, it is imperative to complement the analysis of smaller regions with the Köppen-Trewartha climate system.

Graphical Abstract

This graphical abstract summarizes the projected climate changes in continental Portugal according to the Köppen-Geiger and Köppen-Trewartha climate classification systems, based on three future CMIP6 scenarios (SSPs) for two time periods: 2046–2065 and 2081–2100. The color-coded map illustrates the spatial distribution and shifts in dominant climate types across Portugal, with a clear transition from temperate oceanic and subtropical summer-dry climates toward hotter and drier conditions, especially in central and southern regions. The Köppen-Geiger classification shows a growing dominance of the hot-summer Mediterranean climate (Csa), while Köppen-Trewartha reveals a significant expansion of the Cr (humid subtropical) type, reflecting longer warm periods and reduced precipitation. These shifts are more pronounced in the long-term horizon, highlighting a consistent warming and drying trend across the territory. The graphic emphasizes the limitations of Köppen-Geiger in capturing regional nuances, reinforcing the value of Köppen-Trewartha for finer-scale assessments. The visual synthesis underlines the critical importance of accurate climate classification systems to support future planning and adaptation strategies in sectors such as agriculture, urban development, and water management.