Drought monitoring and early warning (M&EW) systems are an important component of agriculture/silviculture drought risk assessment. Many operational information systems rely mostly on meteorological ...indicators, and a few incorporate vegetation state information. However, the relationships between meteorological drought indicators and agricultural/silvicultural drought impacts vary across Europe. The details of this variability have not been elucidated sufficiently on a continental scale in Europe to inform drought risk management at administrative scales. The objective of this study is to fill this gap and evaluate how useful the variety of meteorological indicators are to assess agricultural/silvicultural drought across Europe. The first part of the analysis systematically linked meteorological drought indicators to remote sensing based vegetation indices (VIs) for Europe at NUTs3 administrative regions scale using correlation analysis for crops and forests. In a second step, a stepwise multiple linear regression model was deployed to identify variables explaining the spatial differences observed. Finally, corn crop yield in Germany was chosen as a case study to verify VIs' representativeness of agricultural drought impacts. Results show that short accumulation periods of SPI and SPEI are best linked to crop vegetation stress in most cases, which further validates the use of SPI3 in existing operational drought monitors. However, large regional differences in correlations are also revealed. Climate (temperature and precipitation) explained the largest proportion of variance, suggesting that meteorological indices are less informative of agricultural/silvicultural drought in colder/wetter parts of Europe. These findings provide important context for interpreting meteorological indices on widely used national to continental M&EW systems, leading to a better understanding of where/when such M&EW tools can be indicative of likely agricultural stress and impacts.
► We analyse 1969–2008 seasonal flow trends using near-natural catchments in the UK. ► Runoff and high flows increased in autumn and winter, especially in the west. ► Spring flows have decreased; ...although long records show evidence of marked regime shift. ► Lack of trends in low flows and summer runoff is contrary to climate projections. ► Strong spatial and temporal heterogeneity is a major obstacle to trend attribution.
A wide range of hydrological trend studies have been published for the UK, but there has not previously been a UK-wide assessment of changes in seasonal river flow regimes in a large number of catchments reflecting the diversity of UK rivers. This represents a gap in research, as climate change impacts are likely to vary regionally and seasonally, and seasonal river flows form the basis of many climate change impact assessments. This study attempts to fill this gap, by analysing trends over the 1969–2008 period in a network of 89 catchments from across the UK. Many UK catchments are heavily disturbed by human influences, so this study primarily focuses on catchments with near-natural flow regimes, to enable climate-driven trends to be distinguished from direct anthropogenic disturbances such as river regulation and abstractions. Trends are characterised for four standard seasons (December–February, March–May, June–August, September–November), for seven flow quantiles. Particular emphasis is placed on examining spatial patterns in observed trend magnitude for median, high and low flows. A set of eight catchments with long records (starting in the 1930s or earlier) are used to assess the representativeness of recent trends in a long-term context, via a moving window trend analysis. The results of this study suggest a much more complex pattern of regional and seasonal variation than revealed in previous work. Some findings resonate with observed rainfall changes, and also with potential future climate change – e.g. increased runoff and high flows in winter and autumn, and decreased flows in spring. The latter is a result which is sensitive to study period, and is not observed in longer records. In summer, there is no compelling evidence for a decrease in overall runoff or low flows, which is contrary to trajectories of most future projections. Overall, the results do not suggest immediate concern for current water resource management on the basis of observed trends alone; however, the differences between observations and model projections suggest these findings should not be viewed complacently, and greater reconciliation between data- and model-based assessments should be sought as a basis for informing water management decisions. The spatial heterogeneity of observed trends (in the lowlands of southeast England especially) suggests caution is needed in extrapolating from small catchments to large regions; understanding this heterogeneity is a major topic for future research.
•We show how the past remains poorly integrated within climate adaptation research.•Historians remain wary of d$eterminism; other approaches can downplay human agency.•We suggest three areas for ...stronger engagement with history in adaptation, namely.•Particularizing adaptation, focus on path dependency, and second-order observation.•A stronger historical focus in adaptation may require a change in research culture.
There is a growing recognition that adaptation to climate change requires an understanding of social processes that unfold across extended temporal trajectories. Yet, despite a move to reconceptualise adaptation as ‘pathways of change and response’ with a deeper temporal dimension, the past generally remains poorly integrated into adaptation studies. This is related to a disavowal of environmental determinism within the academic field of history, which has caused the past to be addressed from other disciplinary perspectives within climate change literature, leading to accusations of over-simplification and neo-determinism. Conversely, whilst a relatively small amount of research within the subdiscipline of historical climatology has engaged with theories from mainstream adaptation to understand societies in the past, there has been little influence in the other direction.
Building on a comprehensive review and critique of existing approaches to historical climate-society research, we argue for three important areas where historians should engage with climate change adaptation. The first area we call particularizing adaptation; this is the development of long-term empirical studies that uncover societal relations to climate in a particular place – including climate’s cultural dimensions – which can provide a baseline and contextualisation for climate change adaptation options. The second, institutional path dependency and memory, argues for a focus on the evolution of formal institutions with a responsibility for adaptation, to understand how historical events and decisions inform and constrain practices today. Our third argument is for an appreciation of the history of ideas and concepts that underpin climate change adaptation. We call for a second-order observation – observation of the observers – within climate change research, to ensure that adaptation does not perpetuate historically-grown power structures.
Attribution of trends in streamflow is complex, but essential, in identifying optimal management options for water resources. Disagreement remains on the relative role of climate change and human ...factors, including water ions and land cover change, in driving change in annual streamflow. We construct a very dense network of gauging stations (n = 1,874) from Ireland, the United Kingdom, France, Spain, and Portugal for the period of 1961–2012 to detect and then attribute changes in annual streamflow. Using regression‐based techniques, we show that climate (precipitation and atmospheric evaporative demand) explains many of the observed trends in northwest Europe, while for southwest Europe human disturbances better explain both temporal and spatial trends. For the latter, large increases in irrigated areas, agricultural intensification, and natural revegetation of marginal lands are inferred to be the dominant drivers of decreases in streamflow.
Plain Language Summary
Reduced water resources availability is one of the most serious impacts of climate change since reductions in streamflow may cause noticeable ecological and socioeconomic impacts. However, attribution of streamflow trends to climate change is complex given the influence of other drivers of catchment change, including human and vegetation water uses, agriculture, and land use change. We show that for northwestern Europe most observed trends in annual streamflow are associated with climate change. However, in southwestern Europe there is a clear mismatch between observed trends in river flows and climate, with increasing vegetation and/or irrigated agriculture better explaining observed changes. Our results highlight the importance of human management in explaining large‐scale hydrological trends and the need to carefully evaluate both climate and land use changes to disentangle drivers of streamflow trends.
Key Points
Streamflow trends in countries bordering the northeast Atlantic show a north‐south latitudinal gradient, with strong decreasing trends in southern regions
Climate trends largely explain the evolution of annual streamflow in northwestern Europe
Climate trends cannot fully explain the large reductions in annual streamflow in southwest Europe, with land use changes and water demand from irrigation playing an important additional role
This study presents a new data set of gauged streamflow (N = 3,224) for Europe spanning the period 1962–2017. The Monthly Streamflow of Europe Dataset (MSED) is freely available at ...http://msed.csic.es/. Based on this data set, changes in the characteristics of hydrological drought (i.e., frequency, duration, and severity) were assessed for different regions of Europe. Due to the density of the database, it is possible to delimit spatial patterns in hydrological droughts trend with the greatest detail available to date. Results reveal bidirectional changes in monthly streamflow, with negative changes predominating over central and southern Europe, while positive trends dominate over northern Europe. Temporally, two dominant patterns were noted. The first pattern corresponds to a consistent downward trend in all months, evident for southern Europe. A second pattern was noted over central and northern Europe and western France, with a predominant negative trend during warm months and a positive trend in cold months. For hydrological drought events, results suggest a positive trend toward more frequent and severe droughts in southern and central Europe and conversely a negative trend over northern Europe. This study emphasizes that hydrological droughts show complex spatial patterns across Europe over the past six decades, implying that hydrological drought behavior in Europe has a regional character. Accordingly it is challenging to adopt “efficient” strategies and policies to monitor and mitigate drought impacts at the continental level.
Key Points
The hydrological drought trend shows a decrease over Northern Europe and an increase over the central and South of Europe for 1962–2017
The monthly streamflow trend (Europe) shows a decrease in all months (South) and warm months (North), and an increase in cold months (North)
The Monthly Streamflow of Europe Dataset (MSED) and map viewer is freely available (http://msed.csic.es/)
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