Evaluation of statistical downscaling techniques and projection of climate extremes in central Texas, USA

This study evaluates statistical downscaling techniques using different metrics and compares climate change signals and extreme precipitation and temperature changes under future climate change scenarios in the Bosque watershed, North-Central Texas. The study utilizes observed gridded Daymet data to assess the effectiveness of statistical downscaling techniques. It involves comparing the mean, the 90th percentile, 10th percentile, wet day frequency, and Cumulative Distribution Function (CDF) of climate model simulations before and after downscaling and the Daymet data during the historical period (1981–2005). Furthermore, the study analyzes changes in climate change signals, extreme precipitation, and temperature values under both near-future (2031–2060) and far-future (2070–2099) climate scenarios. The Ratio Delta method (DeltaSD) and Equi-Distant Quantile Mapping (EDQM) statistical downscaling techniques adjust the mean annual, the wet days frequency, the 90th and 10th percentiles, and the CDF of Global Climate Models (GCMs) simulations of historical precipitation and temperature. The downscaling techniques influenced the climate change signal and changes in extreme values in the future climate. When examining future climate projections produced using the DeltaSD method, we observe a more pronounced reduction in precipitation, while simulations generated through EDQM exhibit a higher frequency of heavy precipitation events (R10mm, R20mm) and consecutive dry days (CDD). It's worth noting that the uncertainties associated with the statistical downscaling techniques are relatively small and not statistically significant (≤0.05). In contrast, substantial and significant uncertainties arise from the choice of emission scenarios and the selection of driving GCMs. Across most climate change scenarios, there is a consistent trend towards increased temperatures and extreme temperature indices. The trend of extreme temperature indices shows variation following the choice of emission scenarios where a significant change in temperature extremes was detected under the RCP8.5 emission scenario

Trend analysis of hydro-climate variables in the Jemma sub-basin of Upper Blue Nile (Abbay) Basin, Ethiopia

Article Highlights The annual precipitation of the sub-basin has shown an increasing trend. A considerable upward trend in the annual average temperature was found. The observed rainfall and temperature trends are associated with the hydro-climate trends

Changes in observed rainfall and temperature extremes in the Upper Blue Nile Basin of Ethiopia

Ethiopia, a densely populated country with abundant natural resources, is often hit by climate extreme disasters that cause severe damage to life and property every year in one or the other corner. The frequency and intensity of extreme events have increased in the recent decades due to climate change and variability. This study aimed to analyze the changes in observed rainfall and minimum and maximum temperature extremes in the Upper Blue Nile Basin (UBNB) of Ethiopia from 1980 to 2019 periods. The Mann-Kendall (MK) trend test and Theil-Sen\u27s slope estimator were used to estimate annual and seasonal trends. The rainfall and temperature extremes were analyzed using RClimDex, which is a graphical user interface in R software, by selecting ten rainfall and eleven temperature indices. The results showed a positive trend in annual, dry (March–May) and small rain (October–February) seasons rainfall in more than 54% of the stations and a decreasing trend in the main rain (June–September) season rainfall in 65.4% of the stations. Several extreme rainfall indices showed insignificant positive trends in the basin. Although there is a positive trend in extreme rainfall, the number of consecutive wet days (CWD) and the simple daily intensity index (SDII) show insignificant negative trends in most stations. In addition, a warming trend of the annual and seasonal maximum and minimum temperature extreme indices was noted. Overall, the increase in extreme rainfall and a warming trend in the extreme temperature indices indicate signs of climate change in the UBNB. The findings of this study suggests the need for developing climate change adaptation and mitigation strategies in the UBNB

Strengthening climate change adaptation capacity in Africa- case studies from six major African cities and policy implications

Africa is one of the most vulnerable regions in respect of climate change. As the African continent struggles to adapt to climate change, a variety of measures are being pursued to alleviate the resultant pressures on people, properties and their livelihoods in several African cities. Collectively, they show that climate change adaptation in Africa is not as hopeless as widely claimed, and that there are some promising prospects. The literature shows a deficiency on studies which examine the extent to which climate change adaptation is being pursued in African cities. This paper addresses this need, and outlines some of the most important climate threats (e.g. increasing temperatures, droughts, sea level rise, sea and river flooding) and synergic non-climate factors, as well as recent progress made in respect of implementing climate change adaptation in African cities. Rather than adopt a general description of trends, this research focuses on concrete case studies from six major cities across the central, western, and eastern regions of the African continent (Douala, Lagos City, Dar-es-Salaam, Accra, Addis Ababa and Mombasa). The vulnerability and adaptive capacity status of the studied cities are discussed. Difficulties and challenges encountered in implementing adaptation policies in these areas are also highlighted. Furthermore, some successful examples of climate change adaptation initiatives in the surveyed cities are provided. Finally, the paper outlines some of the policy measures which can be implemented towards strengthening the capacity of African cities to adapt to a changing climate