Is it possible to fit extreme climate change indices together seamlessly in the era of accelerated warming?

Abstract

This study examines the problematic impact of selecting a different base period (colder 1961-1990 vs. warmer 1988-2017), on the trend magnitude of widely used percentile-based extreme temperature indices (e.g., warm/cold spells, warm/cold days and nights). The percentile-based indices are part of a core set of indices (27 in total) that have become a common standard for monitoring climate change, as recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI). The indices were designed to be comparable across regions provided that similar analyses are employed. Unfortunately, the use of different base periods and periods of interest to explore local and global climate change undermines the comparability of findings across regions. When utilizing "day-count" indices with fixed thresholds, the use of different base/ reference periods changes the intercept without influencing the slope (for a given period length). However, this assertion does not hold with percentilebased indices. Our analyses show that percentile-based temperature indices (e.g., days with temperature below the 10 th or above the 90 th percentiles) are particularly susceptible to the problematic use of different base periods. Hence, using percentile-based indices may have adverse effects on researchers' conclusions. The current paper reports the results of a comparative study that used different base periods for the most commonly used percentile-based extreme temperature indices. It was found that the (negative) trend magnitude of the cold percentile-based indices (frequency of cold days and nights and cold spells) is strongly amplified while the (positive) trend magnitude of the warm indices (frequency of warm days and nights and warm spells) is dramatically diminished when percentiles were derived from a base period that included records from the last two decades (e.g., 1981-2010, 1988-2017). These features are even more pronounced when the study period covers only the last 30-40 years. K E Y W O R D S base period, climate change, climate extreme indices, percentile-based indices, warming trends

Indices for daily temperature and precipitation in Madagascar, based on quality‐controlled and homogenized data, 1950–2018

“…Calculations were made with the 'zyp' R package (Bronaugh and Werner, 2019). This package implements the method and was used in many papers, such as Barry et al (2018) and Yosef et al (Yosef et al, 2019;Yosef et al, 2021). The lower and upper limits of trend confidence interval are at 0.025 and 0.975, respectively.…”

Low and High Ambient Temperatures during Pregnancy and Birth Weight among 624,940 Singleton Term Births in Israel (2010–2014): An Investigation of Potential Windows of Susceptibility

“…2019 ), and concomitantly, climate change has increased the frequency and severity of heat waves, and the occurrence of snow events ( Yosef et al. 2016 , 2021 ). Given projected increases in average and extreme ambient temperatures, it is important to investigate the potential effects of climate change on birth outcomes in Israel ( Hochman et al.…”

“…Increases in mean temperature and the frequency and intensity of extreme weather events due to climate change are expected to increase climate-related morbidity and mortality (Basagaña 2018;IPCC 2014). In Israel, summers have become significantly warmer during the last 30 y (Yosef et al 2019), and concomitantly, climate change has increased the frequency and severity of heat waves, and the occurrence of snow events (Yosef et al 2016(Yosef et al , 2021. Given projected increases in average and extreme ambient temperatures, it is important to investigate the potential effects of climate change on birth outcomes in Israel (Hochman et al 2020).…”

Absence of Surface Water Temperature Trends in Lake Kinneret despite Present Atmospheric Warming: Comparisons with Dead Sea Trends

“…As a result of this comparison, we can see accelerating trends in Kinneret near-surface temperature. This reflects accelerating regional atmospheric warming (confirmed by available meteorological measurements of air temperature [40,42,43]) and increasing solar radiation (Figure 4f).…”