Analysis of Recent Mean Temperature Trends and Relationships with Teleconnection Patterns in California (U.S.)

Abstract

The global mean surface temperature has risen since the late 19th century. However, temperatures do not increase uniformly in space or time and few studies have focused on that peculiarity in the State of California. The aim of this research is to deepen our knowledge of the evolution of mean temperatures in the State of California on monthly, seasonal and annual time scales. The period under study comprises 40 years (from 1980 to 2019) and data from 170 meteorological stations were analysed. Statistical techniques, including Sen’s slope and Mann-Kendall, were applied to each of the stations to establish the sign and slopes of trends and their statistical significance. The spatial distribution of monthly, seasonal and annual trends was analysed using the Empirical Bayesian Kriging (EBK) geostatistical technique. The trend analysis was also carried out for the State as a whole. This research also studies the relationships between mean temperatures and nine teleconnection patterns with influence on the Californian climate. To find out these links, a correlation analysis was performed using the partial non-parametric Spearman Test at a 95% confidence level. The study reveals a positive trend of +0.01 °C year−1 for the whole state and that Southern California is getting warmer than Northern California for the study period. On a seasonal scale, the local temperature increased significantly both in autumn and summer (+0.06 °C and +0.035 °C year−1 respectively) from 1980 to 2019. On a monthly scale, the largest increases are found in November at +0.04 °C year−1. Temperatures in February, March, April and May are highly correlated with most of the teleconnection patterns studied in the State of California. West Pacific Oscillation (WPO) teleconnection pattern has shown the highest negative correlation. However, The Pacific Decadal Oscillation (PDO) has a positive correlation with mean temperatures in coastal areas such as Los Angeles, San Francisco and Monterey. Moreover, Antarctic Oscillation (AAO) and Arctic Oscillation patterns (AO) are unlikely to show great influence on average temperature trends in California.

Bioclimatic Characterisation of Specific Native Californian Pinales and Their Future Suitability under Climate Change

“…In short, by 2050, California is predicted to experience a decrease in ombrothermic index (Io) values (higher in the south than in the north) and an increase in the continentality index (Ic) values in the east. Widespread increases in both maximum and minimum temperatures throughout California and decreases in precipitation (except in the north and at high mountain elevations) are also observed, consistent with previous investigations [ 6 , 10 ] and IPCC projections [ 1 , 2 , 3 ]. The projections for the summer ombrothermic indices (Ios 2 , Ios 3 , and Ios 4 ) have shown values that fall below one over the entire state, representing a significant decrease from the current values.…”

“…This temperature increase will cause the sea level to rise, enlarge the frequency and severity of extreme weather events, and cause irreversible damage to ecosystems [ 3 ]. Climate change is affecting California’s biodiversity [ 4 , 5 ] by altering temperature [ 6 , 7 , 8 , 9 ], precipitation [ 10 , 11 , 12 , 13 ], and weather patterns [ 14 , 15 ]. These changes can alter the timing of seasonal events, such as flowering and migration, and cause shifts in species distribution ranges [ 16 , 17 , 18 ].…”

“…Moreover, climate change has a significant impact on the distribution and abundance of tree species [ 29 ]. Rising temperatures and changing precipitation patterns [ 6 , 10 ] are accelerating soil water depletion and increasing the risk of drought, altering the conditions that many plant species need to survive [ 30 ]. These changes are often pronounced in ecotones where species reach their climatic bounds and are replaced by other species [ 31 ].…”

Western pine beetle voltinism in a changing California climate

“…Lassen was predicted to increase from one full summer generation to one full and a 0.3 partial and Modoc to one full and a 0.4 partial (Table 2). Since 1980, climate analyses suggest that southern California has warmed faster than northern California, with the greatest temperature increase in summer and autumn (González-Pérez et al, 2022). Moreover, historical temperature records (Cluck, 2018) and model results (Robbins et al, 2022) Multiple historical observations also highlight that a partial generation can occur, although contribution to population success the following year has been difficult to quantify (Miller & Keen, 1960).…”

Precipitation extremes in the Puna of Atacama Desert, Chile: How to manage current and future uncertainty?

“…This was tested by Antal et al (2021) using many alternatives to interpolate precipitation, with EBK regression being the most accurate of all the methods used. Other work has tested EBKs, for example, in Spain to interpolate bioclimatic trends in drought (Ferreiro-Lera et al, 2022), in the United States for teleconnection and temperature patterns (González-Pérez et al, 2022), or on trends in precipitation and dry days in India (Pathak & Dodamani, 2020).…”