Iberian Peninsula under Climate Change

Iberian Peninsula under Climate Change: History

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Subjects: Meteorology & Atmospheric Sciences

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This entry presents the results of a systematic review of temperature and precipitation extremes over the Iberian Peninsula, focusing on observed changes in temperature and precipitation during the past years and what are the projected changes by the end of the 21st century. The purpose of this entry is to assess the current literature about extreme events and their change under global warming. Observational and climate modeling studies from the past decade were considered in this entry.

extremes
extremes indices
temperature and precipitation extremes
climate change
bias correction
regional climate modeling

1. Introduction

There are indications that climate change is responsible for most of the change in risk associated with weather-related disasters over Europe [1]. Simultaneously, the increase in the frequency and intensity of Europe’s extreme events has been well documented in several studies (e.g., [2,3]). The Paris Agreement is the global answer to minimize the risk from climate change by setting up a long-term common threshold of warming of the planet below 2 °C, preferably to 1.5 °C, compared to pre-industrial levels. To achieve this limiting temperature, serious economic and social transformations must occur to achieve climate neutrality by mid-century. However, according to the latest climate update issued by the World Meteorological Organization (WMO), there is a likelihood that the 1.5 °C warming will be temporarily reached in the next 5 years.

Although extreme events are part of the natural climate variability, the observed changes in extreme events are linked with the intensification of the event, such as an increase in extreme temperature (cold or hot) or an increase in the number of precipitation events in some regions [8]. Temperature and precipitation are expected to be affected by changes in their variability as they are two of the elements of the climatic system. Hence, most of those studies focus on temperature and precipitation.

These facts prompt several studies about climate change and climate variability on the IP and/or Europe yielding a significative high number of studies. The IP is particularly vulnerable to climate change due to its geographic location and climatic characteristics, and it is one of the areas where extreme temperature episodes, such as heat waves and cold spells, are expected to increase in frequency in the future [9,10,11,12].

2. Analysis on Research Results

Recent literature suggests that projections of extreme temperature events increase at a faster rate than global mean surface temperature increases (e.g., [35]), while others point to a linear relationship between the mean response of the intensity of temperature extremes in climate models to changes in the global mean temperature (e.g., [24,36], regardless of the considered emissions scenario [21,24].

In a warming scenario, it is almost certain that increases in the frequency and magnitude of daily warm temperature extremes and decreases in the frequency and magnitude of daily minimum temperature extremes might occur this century [34]. So, it is expectable that extreme weather phenomena related to air temperatures, such as heatwaves and cold spells, are likely to change towards higher maximum temperatures and more hot days [5,6,11,38,41].

Nevertheless, RCMs are still a trustworthy tool to provide more detailed representations of past and present-day climate and climate variability, in particular, for events located in the tails of the distribution. For example, a RCM study from [71] covering a number of geographical domains (Africa, Central America, South America, India, and the Mediterranean) concluded that the added value of using RCMs is the improved representation of high precipitation events. The ability of models to represent extreme events has been the object of investigation for some time. The authors of [90] carried out simulations within the EURO-CORDEX project, using a multi-model ensemble with different resolutions (12 km and 50 km), driven by ERA-Interim for a 20-year period. The authors showed that simulation of extreme temperature is sensitive to the convection and microphysics schemes. Most models exhibit an overestimation of summertime temperature extremes in Mediterranean regions and an underestimation over Scandinavia.

In multi-physics ensembles models, the same model is used for climate simulations using a variety of microphysics schemes or a combination of schemes. Generally, the resulting dispersion amplifies under the future scenario leading to a large drift accompanying the mean change signals, as large as the magnitude of the mean projected changes and analogous to the spread obtained in multi-model ensembles. Moreover, the sign of the projected change varies depending on the choice of the model physics in many cases [17].

3. Summary

The present study was a comprehensive review of the latest decade of published research about extreme weather and climate extremes over the Iberian Peninsula (IP) and explored the methods and climate change indicators used in observational and modeling studies for the historical climate and 21st-century projections. Considering the amount of information presented in the Results section, Table 1 and Table 2 highlighted the major findings.

Table 1. Summary of changes observed in the Iberian Peninsula over the last 50 years for temperature and precipitation.

Table 2. Summary of projected changes for temperature and precipitation over the Iberian Peninsula for the 21st century.

Globally, major significant findings point to a global past warming trend that most likely will continue the ongoing years. This consistent warming trend can also be found in hot extremes. Warming greater than the global average (between 0.8 °C and 1.2 °C) has already been experienced in some regions and seasons. The IP is also experiencing warming consistent with other regions and magnitude. Information on present warming relative to different past periods allows us to say that in the last decades, the IP warmed by 0.75 °C to 1.5 °C relative to pre-industrial (1850–1900) and at a faster pace than the global mean surface temperature of 0.87 °C [4].

Projections point for increases of 1.5 °C for mid-century [4], with regions such as the IP expecting greater changes of up to 8 °C [6], with severe hot days and a notable reduction in cold extremes [5,6,20,36,37,38,52].

Recent studies have highlighted that projections for extreme temperature events increase at a faster rate than mean temperature [35], while others referred to a linear relationship between the intensity of the mean response of extreme temperature and changes in the global mean temperature [33,37].

The effects of global warming on precipitation are not so clear as for temperature and depend on the region. Globally, heavy precipitation is increasing, confirming theory and early model results [1]. In some regions, heavy precipitation events are related to large-scale dynamic features, such as frontal systems, which implies dynamic changes, such as the expansion of the Hadley cells or shifts in the storm tracks, may substantially alter the heavy precipitation response [1].

Overall, a reduction in mean precipitation for southern Europe [4] is expected, although [1] showed changes in the frequency of extreme events (increases) along with increases in the contribution of extreme precipitation to total precipitation. The number of days with very heavy precipitation over Europe has increased [1]. This behavior is also shown for the Mediterranean region [26,27], independently of the warming scenario, and appears to be specific to heavy precipitation [36]. One major concern for the IP is related to droughts. The region is highly vulnerable to dryness, and in recent years, there has been evidence of a drying trend [36].

This entry is adapted from the peer-reviewed paper 10.3390/cli9090139

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