Magnitude and frequency of heat and cold waves in recent decades: the case of South America

Guido Ceccherini,Claudia Patricia Romero,Iban Ameztoy,Cesar Carmona-Moreno,Simone Russo

doi:10.5194/nhess-16-821-2016

Guido Ceccherini, Claudia Patricia Romero + Show 3 more

Open Access

https://doi.org/10.5194/nhess-16-821-2016

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Abstract

Abstract. In recent decades there has been an increase in magnitude and occurrence of heat waves and a decrease of cold waves, both of which may be related to the anthropogenic influence. This study describes the extreme temperature regime of heat waves and cold waves across South America over recent years (1980–2014). Temperature records come from the Global Surface Summary of the Day (GSOD), a climatological data set produced by the National Climatic Data Center that provides records of daily maximum and minimum temperatures acquired worldwide. The magnitude of heat waves and cold waves for each GSOD station are quantified on an annual basis by means of the Heat Wave Magnitude Index and the Cold Wave Magnitude Index. Results indicate an increase in intensity and in frequency of heat waves, especially in the last 10 years. Conversely, no significant changes are detected for cold waves. In addition, the trend of the annual temperature range (i.e. yearly mean of Tmax – yearly mean of Tmin) is positive – up to 1 °C per decade – over the extratropics and negative – up to 0.5 °C per decade – over the tropics.

Highlights

In the coming decades, climate change will expose hundreds of millions of people to its impacts (Pachauri et al, 2014; Solomon et al, 2007; WHO, 2015)
Temperature records come from the Global Surface Summary of the Day (GSOD), a climatological data set produced by the National Climatic Data Center that provides records of daily maximum and minimum temperatures acquired worldwide
The analysis presented below follows a three-step procedure that is divided as follows: (1) selection of temperature records with at least 30 years of data; (2) calculation of the Heat Wave Magnitude Index (HWMI) and Cold Wave Magnitude Index (CWMI) for the period 1980–2014; (3) estimation of the trend for annual mean of daily maximum temperature, annual mean of daily minimum temperature, and the mean temperature range (i.e. MTR = annual mean of daily maximum − annual mean of daily minimum temperature; see Sect. 2.2 for further details)

Summary

Introduction

Climate change will expose hundreds of millions of people to its impacts (Pachauri et al, 2014; Solomon et al, 2007; WHO, 2015). Many areas of the world – Africa and Latin America, among others (Niang et al, 2014) – will have to deal with increases in temperature and changes in extreme weather conditions such as heat waves, altering the probability of experiencing major heat waves in the very near future (Field et al, 2012). The 2003 European heat wave (Beniston, 2004) illustrated how infrastructures, even in highly developed countries, can fail to deal with such environmental challenges. From this perspective, variability and changes in extreme temperature regimes present a considerable challenge for South America (Magrin et al, 2014). A complete picture, along with a robust assessment, of temperature extreme regimes might provide essential information on the climate-related risks that society face, and how these risks are changing

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