Key message 2 – Adapting to higher variability in temperature and precipitation will be more challenging than adapting to increases in average temperature.

Agricultural adaptation will be required in the face of growing climate risk and uncertainty. Adaptation is the process of adjustment to the actual or expected climate and its effects (IPCC, 2014), making agricultural production less sensitive to weather and climate. However, maladaptation can occur, where the process of adaptation leads to new vulnerabilities or harms different segments of the population (UNEP, 2021). Thus, undertaking adaptation efficiently and effectively is difficult.

The process of adaptation will typically incur costs, often in foregone revenue or capital expenditures. But not adapting will be more costly, since successful adaptation will, on average, increase yields. Like other agricultural outcomes, however, the profit implications of adaptation will depend on weather-change realisations. For example, investments into irrigation practices may be unprofitable if precipitation remains high. In such an instance, it would have been more profitable to avoid the irrigation investment and continue to rely on rainfall. Here the farmer was basing the investment decision on information available ex ante while the final profit outcome was determined by precipitation realisations ex post.

Adaptations can be conceptualised as follows (Mendelsohn, 2000, Lemoine, 2018):

  • Ex ante adaptation: where actions are based on expectations of future weather, such as farmers investing in flood-resilient seeds
  • Ex post adaptation: where actions are based on realisations of weather change, such as farmers watering crops during a heatwave
  • Undertaken by private or public actors
  • Occur indirectly: when actors are not responding to weather at all, such as a farmer adopting technology to maximise profit, and as a by-product lowering the sensitivity of their yields to climate change

Ex ante adaptation

Ex ante adaptation is undertaken beforehand and on the basis of expected changes in weather and climate. This has the benefit of allowing a greater range of potential adjustments, such as switching crops or changing planting patterns. However, it also carries greater ex post risk, since the degree to which the adjustments pay off depend on weather-change realisations. Thus, as the variability of weather and climate increases, the benefits of ex ante adaptation strategies also become more variable. For example, investing in flood-tolerant rice varieties in India increased yields by around 45% when they were flooded for 10 days, but importantly had no reduction in yields when flooding did not occur (Dar et al., 2013). Since this technology had no negative yield penalty when the weather was good, the variance of possible outcomes was lower. This helps to minimise the cost and risk of investment. Nevertheless, investing in flood-tolerant rice still incurs an upfront adjustment cost (such as the purchase of new or more expensive seeds) and so would lower profits ex post if no flooding occurred, even if expected profits were higher than with regular seeds.

Ex post adaptation

Ex post adaptation, on the other hand, occurs after weather or climate is observed. As a result, a smaller range of adaptation strategies can be deployed ex post, such as increased watering or mulching around plants. These may be less effective than ex ante strategies but will only be deployed when the weather determines that it is profitable to do so. Ex post adaptation might therefore be preferred to ex ante when there is a high degree of weather and outcome variability, when ex ante strategies have high upfront costs, or when ex post strategies offer effective means of addressing weather shocks. Some adaptation actions might rely on scarce resources, which increases their costs and makes them more valuable as an ex post strategy used only once a weather event has arrived (Lemoine, 2018). For example, using groundwater can help alleviate water scarcity in the short-term, but offers an unsustainable long-term solution (Fishman, 2018). Ex post adaptation can help to avoid large losses when the variability of outcomes is large, and actors might default more to it given its smaller risk profile. However, in many cases, ex post solutions will be inadequate to address increasing extreme weather.

Underpinning the efficiency of ex ante or ex post decisions is the importance of information and expectations, and the capacity to alleviate risk and respond to shocks.