Implications For Management

The uncertainty of climate makes the year-to-year practice of farming similar to an ongoing game of chance. Every year before planting the farmer decides what and how much to grow (or, if to grow) and then gambles on whether climate conditions during the growing season will allow his management decisions to, in effect, "pay off". Seasonal climate forecasts based on the predicted development of the ENSO mechanism could have the effect of improving the odds in the farmer's favor, the notion of which finds support in the results presented here and in Mauget and Upchurch (1998). Although some conditional probabilities found here linking SST to concurrent seasonal climate are strong, they are not absolute. In addition, two tiered numerical (Bengtsson et al. 1993) and numerical-statistical forecasting schemes will introduce additional uncertainty through the SST forecast. Given that ENSO forecasts may reduce but not eliminate climate uncertainty, ENSO forecasts predicting seasonal growing conditions before planting might be compared to "loading the dice" in the farmer's favor. But even loaded dice behave with some degree of randomness, thus the potential for gain from ENSO forecasts of opportunity should not be measured based on the outcome a single cycle of forecast followed by an adjusted management strategy; i.e., a single "throw of the dice". Instead, it should be based on the net outcome of a series of such cycles associated with ENSO events occurring periodically over an agricultural operation's lifetime. Considering the relatively sporadic occurrence of ENSO events, the use of ENSO forecasts in long term management might be compared to being given occasional access to loaded dice in agriculture's ongoing gambling situation. The suggestion made here is that producers of winter wheat may be offered such dice more frequently, and that they may be more heavily weighted towards certain climate and yield outcomes. As a result, we propose that the potential for long-term economic gain over the growing regions of the central U.S. may be greater for winter wheat than for corn . This is based on the following observations: Both ENSO phases favor northern winter periods in frequency of occurrence, which suggests that forecasts of opportunity might be issued more frequently for winter conditions than for summer. Higher frequency of winter ENSO activity is evident in the higher incidence of extreme SST conditions during winter . Fully developed ENSO conditions are primarily a feature of northern winter, with northern summer periods typically associated with initial or final stages of event development. Thus while anomalous northern winter conditions are characteristic of most ENSO events, only certain events develop quickly enough, or persist long enough, to produce anomalous northern summer conditions. More reliable winter ENSO forecasts might be implied in the higher levels of significance in skewness about the median, and the incidence of extreme quartile conditions in the analyses of El Niño and La Niña winter climate, when compared with the analyses of El Niño and La Niña summer climate. This is most likely due to the increased incidence of extreme decile SST conditions during October-February, a period of peak ENSO strength. Extreme decile SST conditions are consistent with stronger coupling between the oceanic and atmospheric components of ENSO, and more robust effects on midlatitude atmospheric circulation. With regard to yield outcomes, the tendency to other than normal yields in Tables 1 and 2 is generally more significant in the winter wheat results, and a comparison of the patterns of significance in the corn and winter wheat yield analyses shows a more uniform and greater magnitude of effect on wheat yield. It is worth noting that the strongest effects evident in Tables 1 and 2 is on a crop dependent on winter precipitation and grown in the southernmost part of the study region; i.e., the impacts on winter wheat yields in Texas and Oklahoma. As the winter climate effects found here over Texas and Oklahoma extend across lower latitude areas of the continental U.S., (WEWC Technical Report #2, 1998) strong yield impacts might also occur over regions not considered here. Schonher and Nicholson's (1989) study of the effects of the El Niño phase on California rainfall shows a significant tendency to above average annual rainfall in the southern portion of that state. Anecdotal evidence of warm phase effects on agriculture in this region might be found in the impact of the 1997/98 El Niño event on the winter romaine lettuce crop (Associated Press, 1998). Heavy rains associated with that event led to delays in planting, seedling mortality, and fungus infestation due to standing water in the fields. The negative effects on yield might be inferred from the resulting increase in wholesale prices from $10 to $50 per case. The use of ENSO forecasts to anticipate effects on climate and agricultural production may be also be possible in Florida, where ENSO-related rainfall effects are apparent (Ropelewski & Halpert; 1986,1989) and winter produce crops are cultivated and harvested during seasons of peak ENSO activity. Abnormally wet conditions over Florida during the spring of 1998 led to delays in harvesting, planting and fieldwork (Weekly Weather and Crop Bulletin,1998). These examples suggest the possibility that the previous discussion may be more broadly applied; i.e., that the potential for long-term economic gain over the continental U.S. may be greater for winter crops than for summer crops in general. To Top To Home