Abstract
In semi-arid highlands of northern Ethiopia, episodes of droughts of varying severity and duration occur. The occurrence of these droughts is associated mainly with the seasonal rainfall variability. This study attempts to investigate the temporal and spatial variability of climate parameters, particularly rainfall and temperature for the period 1954-2008. Standardized rainfall anomaly was used to examine the temporal characteristics of climate variability and determine the prevalence of droughts. Analysis of variance was also employed to establish significant differences in rainfall characteristics amongst different in-situ stations. The baseline climate data from each station was also spatially interpolated using ordinary kriging technique. The temporal analysis indicated an overall slight decrease in rainfall and an overall increase in the mean annual minimum and maximum temperatures over the study period. The analysis further revealed that the average annual minimum temperature over the region has been increasing by about 0.72ºC every ten years while average annual maximum temperature has been increasing by about 0.36ºC per decade. This shows that the northern part of Ethiopia is warming faster than the national average of 0.25ºC per decade. It is also observed that the average annual minimum temperature is increasing faster than average annual maximum temperature, which is an indication of warming nights over the years. Key words: Weather, variability, drought, rainfall, temperature.
Highlights
Changes in temperature and rainfall patterns are widely observed in many semi-arid parts of the developing world that are likely to become even hotter and dryer with time (Collier et al, 2008)
Estimates from the historical records of precipitation for the period 19542008 indicate that the mean annual rainfall is 560.7mm while the mean annual kiremti rainfall is 473mm, 84% of the annual rainfall
The temporal analysis indicated that rainfall pattern in the study area exhibited a very high variability over time and is quite often accentuated with positive and negative anomalies (Figure 3)
Summary
Changes in temperature and rainfall patterns are widely observed in many semi-arid parts of the developing world that are likely to become even hotter and dryer with time (Collier et al, 2008). The average temperature rise in Africa is faster than the global average and is likely to persist in the future This warming occurred at the rate of about 0.5oC per decade with a slightly larger warming in crops are grown close to the thermal tolerance limits (Collier et al, 2008). The Third Assessment Report of the International Panel on Climate Change (IPCC) indicated that developing countries are expected to suffer most from the negative impacts of climate change and climate variability (IPCC, 2001)1 This is due to the economic importance of climate- sensitive sectors for these countries and to their limited human, institutional and financial capacity to anticipate and respond to the direct and indirect effects of climate change and variability. In most developing countries and in many African countries, agricultural production including access to food is projected to be severely compromised by climate change and variability (IPCC, 2007a)
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