Reassessing long-term drought risk and societal impacts in Shenyang, Liaoning Province, north-east China (1200–2015)

The occurrence of two severe droughts in north-east China since 2000 has raised attention in the risk presented by droughts. This paper presents a historic drought series for Shenyang in Liaoning Province, north-east China, from 1200 CE to the present with a reconstructed long precipitation series (1906–2015) augmented with historical documentary accounts. Analysis of the instrumental series using a standardized precipitation index (SPI) and extending it using historical records has produced a combined series spanning over 8 centuries. The combined long series was analysed for patterns in drought frequency, severity and typology. Three droughts comparable to those since 2000 occur in the instrumental series during the early 20th century (i.e. 1907, 1916–1918 and 1920–1921), and coeval archival sources reveal the human impacts of these severe droughts. The archival sources demonstrate how reduced vulnerability resulting from societal and cultural changes in the early 20th century helped prevent the loss of life experienced during comparable severe droughts at the end of the 19th century (1887 and 1891). Incorporating a longer temporal perspective to drought analysis shows that onset is often earlier than is documented explicitly within the archives, and so combined SPI series for a region could provide an early warning of drought development expressed as a water deficit in the previous year. Analysis of archival data provides a rich historical description of impacts and societal responses to severe drought. The archives provide a rich historical description of drought impacts and responses at the personal and community level whilst also detailing the different roles played by communities, state and international organizations in responding to events.

Reassessing long-term drought risk and societal impacts in Shenyang, Liaoning province, Northeast China (CE 1200–2015)

The occurrence of two severe droughts in Northeastern China since CE 2000 has raised attention in the risk presented by droughts. This paper presents a historic drought series for Shenyang in the Liaoning province, NE China since CE 1200 to present, with a reconstructed long precipitation series (1906–2015), augmented with historical documentary accounts. Analysis of the instrumental series using a standardised precipitation index (SPI) and extending it using historical records has produced a combined series spanning over eight centuries. The combined long series was analysed for patterns in drought frequency, severity and typology. Three droughts comparable to those since CE 2000 occur in the instrumental series during early twentieth century (e.g. 1907, 1916–18 and 1920–21), and coeval archival sources reveal the human impacts of these severe droughts. The archival sources demonstrate how reduced vulnerability resulting from societal and cultural changes in the early twentieth century helped prevent the loss of life experienced during comparable severe droughts at the end of the nineteenth century (1887 and 1891). Incorporating a longer temporal perspective to drought analysis shows that onset is often earlier than is documented explicitly within the archives, and so combined SPI series for a region could provide an early warning of drought development expressed as a water deficit in the previous year. Analysis of archival data provides a rich historical description of impacts and societal responses to severe drought. The archives provide a rich historical description of drought impacts and responses at the personal and community level, whilst also detailing the different roles played by communities, state and international organisations in responding to events.

Changes and variability of spring-summer air temperature in Czechia during the past 300 years: comparison of instrumental, documentary and natural proxy data

Instrumental series, documentary and natural proxy air temperature reconstructions from the area of Czechia were employed to demonstrate spring/summer temporal variability and changes during the 1701–2010 period. Various statistical methods were applied to evaluate cold/warm periods, extreme seasons, oscillations and trends of individual series and also differences between them. Additional reconstructions from the Western and Central Europe were added to examine the role of geographical distance and type of climatological reconstruction. Instrumental series and documentary reconstructions agree well on the occurrence of cold/warm periods and extremes. There is a higher concentration of cold periods during the 18th and particularly 19th centuries. All of the series convincingly represent a positive temperature trend related to anthropogenic global warming. A tree-ring reconstruction contains a larger proportion of low-frequency signal. Despite spatial distance it has been recognized that an affinitive series such as tree-ring analyses from mountainous areas or reconstructions dealing with grape harvest-dates records share a vast extent of mutual variability.

Assessing extreme droughts in Spain during 1750–1850 from rogation ceremonies

Among the different meteorological hazards, droughts are those with the highest socio-economical impact on the Iberian Peninsula. Drought events have been largely studied in the instrumental period, but very little is known about the characteristics of droughts in the preinstrumental period. In this work, several series of rogation ceremonies are used to identify severe droughts within the period 1750–1850. The overlapping of the rogation series with some instrumental series served to identify some climatic characteristics of rogation ceremonies: (a) during spring, rainfall deficits needed to celebrate rogation ceremonies are smaller than in any other season; (b) the hydrological deficit in a particular region increases with the number of locations celebrating rogations simultaneously. On the other hand, it was found that between 1750–1754 and 1779–1783 are probably the driest periods of the 101 analyzed years. Both show an important number of rogations all over Iberia and during all the seasons. The most extended drought of this period occurred during the spring of 1817, affecting 15 of the 16 locations studied. This drought was influenced by the Tambora eruption (1815). The study of the climate footprint of this eruption and its comparison with similar situations in the series suggest that the spring drought of 1824 may be associated with the eruptions of the Galunggung and Usu volcanoes (1822). Further studies are required to confirm this fact and understand the atmospheric mechanisms involved.

Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium

A statistical framework for comparing the output of ensemble simulations from global climate models with networks of climate proxy and instrumental records is developed, focusing on near-surface temperatures for the last millennium. This framework includes the formulation of a joint statistical model for proxy data, instrumental data and simulation data, which is used to optimize a quadratic distance measure for ranking climate model simulations. An essential underlying assumption is that the simulations and the proxy/instrumental series have a shared component of variability that is due to temporal changes in external forcing, such as volcanic aerosol load, solar irradiance changes and greenhouse gas concentrations. Two statistical tests are formulated. Firstly, a preliminary test to establish whether a significant temporal correlation exists between instrumental/proxy and simulation data. Secondly, the distance measure is expressed in the form of a test statistic of whether a forced simulation is closer to the instrumental/proxy series than unforced simulations. The proposed framework allows any number of proxy locations to be used jointly, with different seasons, record lengths and statistical precision. The new methods are applied in a pseudo-proxy experiment. Here, a set of previously published millennial forced model simulations, including both "low" and "high" solar radiative forcing histories together with other common forcings, were used to define "true" target temperatures as well as pseudo-proxy and pseudo-instrumental series. The pseudo-proxies were created to reflect current proxy locations and noise levels, where it was found that the low and high solar full-forcing simulations could be distinguished when the latter were used as targets. When the former were used as targets, a greater number of proxy locations were needed to make this distinction. It was also found that to improve detectability of the low solar simulations, increasing the signal-to-noise ratio was more efficient than increasing the spatial coverage of the proxy network. In the next phase of the work, we will apply these methods to real proxy and instrumental data, with the aim to distinguish which of the two solar forcing histories is most compatible with the observed/reconstructed climate.

Assessing extreme droughts in the Iberian Peninsula during 1750–1850 from rogation ceremonies

Among the different meteorological risks, droughts are the ones with the highest socio-economical impact in the Iberian Peninsula. Drought events have been largely studied in the instrumental period, but very little is known about the characteristics of droughts in the preinstrumental period. In this work, new series of rogation ceremonies identify severe droughts within the period 1750–1850. The overlapping of the rogation series with some instrumental series served to identify some climatic characteristics of rogation ceremonies: a) during spring, rainfall deficits needed to celebrate rogation ceremonies are smaller than in any other season; b) when the number of location celebrating rogations increases in a region the hydrological deficit on each location increases as well. On the other hand, it was found that the periods 1750–1754 and 1779–1783 are probably the driest periods of the 101 analyzed years. Both show an important number of rogations all over the Iberian Peninsula and during all the seasons. The most extended drought of this period occurred during the spring of 1817, affecting 15 of the 16 locations studied. This drought was influenced by the Tambora eruption (1815). The study of the climate footprint of this eruption and its comparison with similar situations in the series suggest that the spring drought of 1824 may be associated with the eruptions of the Galunggung and Usu volcanoes (1822). Further studies are required to confirm this fact and understand the atmospheric mechanisms involved.

The Greenhouse Effect and Climatic Trends in Czechoslovakia

The contribution summarizes the hitherto knowledge of the anthropogenic intensification of the greenhouse effect and its reflection in the instrumental series of meteorological elements. The climatological trend on the territory of the CSFR is characterized according to long-year series and in the last 40 years. The forecast of the development of the climate in the regional extent is discussed according to the scenarios based on instrumental observations and paleoclimatic reconstructions.