Cereal harvest dates in the Czech Republic between 1501 and 2008 as a proxy for March–June temperature reconstruction

Abstract

Cereal crop harvests reflect the weather patterns of the period immediately preceding them, and thus the dates at which they begin may be used as a source of proxy data on regional climate. Using systematic phenological observations in the Czech Lands (now known as the Czech Republic) after 1845, together with exploration of further surviving documentary evidence (chronicles, diaries, financial accounts etc.), it has proved possible to create series of winter wheat harvest dates for the period 1501-2008. Employing linear regression, the harvesting dates of the main cereal species (wheat, rye, barley, oats) were first converted to winter wheat harvest days and then normalised to the same altitude above sea level. The next step consisted of using series of winter wheat harvest dates to reconstruct mean MarchJune temperatures in the Czech Republic, applying standard palaeoclimatological methods. Series reconstructed by linear regression explain 70% of temperature variability. A profound cold period corresponding with late winter wheat harvests was noted between 1659 and 1705. In contrast, warm periods (i.e. early winter wheat harvests) were found for the periods of 1517-1542, 1788-1834 and 1946-2008. The period after 1951 is the warmest of all throughout the entire 1501-2008 period. Comparisons with other European temperature reconstructions derived from documentary sources (including grape harvest dates), tree-rings and instrumental data reveal generally close agreement, with significant correlations. Lower correlations

Recent growth coherence in long-term oak (Quercus spp.) ring width chronologies in the Czech Republic

“…Although CZ oak TRW chronologies demonstrate no direct relation to air temperature, rising temperatures and changes in precipitation distribution during the growing season are obviously associated with a higher risk of drought occurrence. For example, a precipitation decrease in the first half of the growing season and an increase in the second half have been reported for some parts of the Czech Republic and for central Europe in the past 2 decades (Bauer et al 2010, Možný et al 2012, Brázdil et al 2015. Consequently, a higher intensity of drought, together with a higher variability of precipitation regime, has a potential for negative effects on tree growth.…”

“…All 3 chronology versions (standard, residual and ARSTAN) generated from ARSTAN software (Cook & Krusic 2005) were considered. The first-order autocorrelation (AC1) was calculated for all 9, slightly different, variants of each sub-chronology and for the mean CZ precipitation series (Brázdil et al 2012) that was used as a target. A suitable detrending technique was chosen, based on the highest similarity of autocorrelation structure between proxy and climate data.…”

Winter temperature variations over the middle and lower reaches of the Yangtze River since 1736 AD

“…Outside of China, many great reconstructions extending back 500-1000 yr using historical documents have been developed during the past few decades. For example, in Japan, summer and winter temperature variations were reconstructed from several historical sources, which included cherry-tree flowering date records, lake freezing date records and weather diary records (Mikami, 2008 Brázdil et al (2005Brázdil et al ( , 2010 and Luterbacher et al (2006Luterbacher et al ( , 2012, and seasonal temperatures with a high resolution in key climatic periods, i.e., the Medieval Warm Anomaly and Little Ice Age, were reconstructed using information obtained from narrative sources, dairies and (bio)physical data (dates of river and harbour freezing, cereal and grape harvests), among other sources (e.g., Pfister, 1992;Luterbacher et al, 2004;Xoplaki et al, 2005;Dobrovolný et al, 2010;Leijonhufvud et al, 2010;Možný et al, 2012).…”

Autumn temperature deduced from historical records of autumn tints phenology of maple tree in Kyoto, Japan

“…近年は，気候変動が様々な点で注目される。気候 変動をもたらす要因について種々の議論があるが， 日本を含む極東地域は，太陽活動の盛衰と気温変化 と の 間 に か な り 高い 相 関 が見 ら れ る 地 域 で ある (Shindell et al, 2001;Waple et al, 2002)。また，太陽 活動の盛衰に対して，この地域の気候応答に 10 年か ら 20 年程度の遅れのあることが報告されている (Shindell et al, 2001;Waple et al, 2002;Aono and Kazui, 2008;Wang and Zhang, 2011)。時間スケールの 長い気候変化の原因を詳しく調べるには，温室効果 ガスの濃度上昇や都市昇温がまだなかった近代気象 観測開始前の時代における古気候の復元が必要なこ ともある。 長期間にわたる気候変化を復元する研究方法には さまざまなものがある。数百年スケールの気候変化 を復元・解析するために，長期にわたり観測された 植物季節データを使用する方法がしばしば採用され てきた (Sparks and Carey, 1995;Ahas, 1999;Defila and Clot, 2001;Rutishauser et al, 2007)。また，植物季節 観測が行われなかった場合でも，古い日記などの古 記録中の植物季節情報を用いる方法もある。たとえ ば欧州では，古記録中に残されていたワイン用のブ ドウの収穫時期 (Chuine et al, 2004;Garnier et al, 2011)や，穀物の収穫時期 (Možný et al, 2012) …”