Danny Blair

Vulnerability to Tropical Cyclones: Evidence from the April 1991 Cyclone in Coastal Bangladesh

In this article we report the results of a survey conducted in two coastal communities of Bangladesh less than two weeks after they were hit by the severe cyclone of April 29, 1991. It was found that almost all of the surveyed heads of households had received early warnings of the cyclone. Nevertheless, a majority of the respondents did not leave their homes to seek shelter. The two most common reasons given for this passive reaction were (i) fear of burglary and (ii) disbelief of the warnings. Thus, it appears that the existing system of early warnings is not having its intended effect and that it, and related disaster mitigation policies, need to be revised. Some suggestions are made as to what could be done.

The Kirchhofer technique of synoptic typing revisited

Two errors in the Kirchhofer technique of synoptic typing are revealed. The first error interferes with the attempt to ensure that grids classified as similar are sufficiently similar at the sub-grid level. The second, and less important, error involves the conversion of Kirchhofer scores to correlation coefficients. The consequences of these errors are demonstrated by comparing the results of two classifications, one with the errors included, one with the errors removed. The classification based on the original algorithm allows many grids to be classified as similar even though they are not (as defined by the users similarity thresholds). The classification based on the corrected algorithm produces results that might not be acceptable to climatologists attempting to summarize a regions synoptic regime with a small number of synoptic types.

Effect of Regional Climate Warming on the Phenology of Butterflies in Boreal Forests in Manitoba, Canada

ABSTRACT We examined the effect of regional climate warming on the phenology of butterfly species in boreal forest ecosystems in Manitoba, Canada. For the period 1971–2004, the mean monthly temperatures in January, September, and December increased significantly, as did the mean temperatures for several concurrent monthly periods. The mean annual temperature increased ≈ 0.05°C/ yr over the study period. The annual number of frost-free days and degree-day accumulations increased as well. We measured the response of 19 common butterfly species to these temperature changes with the date of first appearance, week of peak abundance, and the length of flight period over the 33-yr period of 1972–2004. Although adult butterfly response was variable for spring and summer months, 13 of 19 species showed a significant (P < 0,.05) increase in flight period extending longer into the autumn. Flight period extensions increased by 31.5 ± 13.9 (SD) d over the study period for 13 butterfly species significantly affected by the warming trend. The early autumn and winter months warmed significantly, and butterflies seem to be responding to this warming trend with a change in the length of certain life stages. Two species, Junonia coenia and Euphydryas phaeton, increased their northerly ranges by ≈150 and 70 km, respectively. Warmer autumns and winters may be providing opportunities for range extensions of more southerly butterfly species held at bay by past climatic conditions.

Short-period temperature variability at Winnipeg, Canada, 1872-1993 : Characteristics and trends

SummaryTemperature variability in Winnipeg, Canada, was assessed by determining average and extreme temperature ranges over 1, 2, 5, 10, and 15-day intervals, on a monthly basis, for the period of 1872–1993. Trends in the monthly averages for each of the intervals were also examined.The results show that Winnipeg experiences a very large amount of short-term temperature variability, especially over 2, 5, 10 and 15 days. The monthly average diurnal ranges vary from about 9 to 14 °C, while the 15-day average ranges are about two to three times as large. In general, average temperature ranges over the two shortest intervals (1 and 2 days) are slightly greater in the warm-season months than in the cold-season months, but the averages for the three longest intervals are inversely related to mean monthly temperature, as are the largest ranges observed in each of the months.Average temperature variability in the months of November through March was found to have decreased quite significantly, and rapidly, during the first two decades of this century. This decrease was likely associated with a decrease in the meridionality of the atmospheric circulation. It also occurred during a time when the average maximum and minimum temperatures in Winnipeg were rising, lending support to the conjecture that a warmer global climate will result in less 1–15 day temperature variability. The rapidity of the change also supports the hypothesis that climate changes tend to be non-linear.

Climate change impacts on hard red spring wheat yield and production risk: evidence from Manitoba, Canada

Abstract: A Just–Pope production function is employed to investigate the effects of historic weather changes on hard red spring wheat yield variability in Manitoba. Field-level data on wheat yield, proportion of wheat seeded area, and fertilizer inputs from the Manitoba Agricultural Services Corporation were employed to determine how temperature and precipitation affect mean wheat yield and production risk, and how projected climate scenarios impact yield variability in heterogeneous risk areas of Manitoba. Variety richness increases average yield and reduces yield variance while varieties protected by plant breeders’ rights increase yield variance. Phosphorus fertilizer is positively associated with average wheat yield while total precipitation is shown to negatively affect mean yield and positively impact yield variability. June precipitation matters while June and July temperatures negatively affect yield. Projected climate change is expected to increase yield variability in both the medium (2034–2050) and long term (2079–2095), both under low- and high-carbon scenarios with production variance effects differing across crop districts. Adaptation strategies may be required to mitigate yield risk effects of climate change resulting in late seeding decisions from increased spring precipitation.