su¢ ciently (not too) convex, leading, all else equal, to lower (higher) tari¤s. The overall impact of the rainfall shock on optimal import tari¤s is, therefore, generally ambiguous, depending on the weight placed by the domestic policy maker on each of these policy objectives, and on the shape of the food demand function. A larger weight placed on domestic pro...ts will enlarge the scope for a rainfall shortage to cause tari¤ reductions. A stronger concern for domestic consumers may have a similar e¤ect, but only if demand is su¢ ciently convex, i.e., if the demand for the agricultural good becomes su¢ ciently inelastic at lower consumption levels.

We proceed by verifying the extent to which the main predictions of our theory are sensitive to assumptions about the timing of the game and the mode of competition. In the basic model, we assume that a rainfall shortage increases the marginal costs of agricultural production, as the a¤ected producers must spend more resources on irrigation in order to achieve a given level of output. However, in some agricultural markets producers may have limited access to irrigation technology, and hence have limited ability to adjust output following the shock. We therefore modify the timing of the game, letting the policy maker, and subsequently the foreign producers, make their optimal decisions in response to an exogenous drop in domestic output. Reassuringly, we ...nd that the results of the basic model remain qualitatively unchanged under this alternative setting, while also showing that a rainfall shortage is more likely to induce tari¤ cuts when producers have greater access to irrigation technology. In another extension to the basic model, we examine if and how our main results depend on the assumption of oligopolistic competition. Applying the theoretical framework of Bagwell and Staiger (2001), who analyze strategic trade policy under perfect competition, we re-examine the e¤ect of a rainfall shortage on optimal import tari¤s when ...rms are competitive rather than oligopolistic. We ...nd, once again, that the key predictions of our basic model remain qualitatively similar.

We then examine empirically the impact of rainfall shocks on e¤ectively applied tari¤s. Using detailed panel data on applied tari¤s and rainfall for 70 nations over 1988-2006, we ...nd that rainfall shortages generally lead to lower applied tari¤s on agricultural imports. The positive relationship between rainfall and import tari¤s is robust to several alternative empirical speci...cations, tends to be stronger in countries with greater access to irrigation, and applies fairly widely across the set of agricultural products and regions considered. The main exception refers to nations in Africa, for which we ...nd no evidence of signi...cant tari¤ adjustment in response to rainfall shocks. This lack of response may plausibly re‡ect the fact that governments of African nations tend to depend more heavily on import tari¤s for revenue (Devarajan et al., 1999). In this case, tari¤ revenue is likely to carry a larger weight on the governments’objective function, and thereby o¤set opposite incentives via pro...ts and/or the consumer surplus. Overall, however, our empirical ...ndings suggest 3