Clearly the grain and cattle sectors of the Montana economy are of significant importance. Climate change that threatens these sectors, poses a serious threat to the overall Montana economy.
3. The Estimated Economic Losses to Agriculture Associated with Climate Change in Montana
Both climate change and its agricultural and economic impacts are difficult to calculate. Projections require professional judgement based on the best evidence available. In public policy discussions aimed at reducing human releases of greenhouse gases (GHG) there tends to be a heavy emphasis on the economic costs associated with adopting those policies. When these costs of controlling GHG are discussed, there is rarely a similar discussion of the economic benefits that are the objective of those climate change public policies, namely avoiding the future costs associated with climate change. The result is a cost-only analysis that would typically produce quantitative and very large measures of the costs associated with policies aimed at reducing future human-caused climate change.
A “cost only” analysis of climate change public policy cannot be categorized as an economic analysis since it is the net costs or net benefits after both the benefits and costs of a public policy have been estimated that matter. Implicit in typical cost-only analyses is the assumption that the benefits of reducing human-caused climate change are known in precise, quantitative, detail, namely, that they are zero. The overwhelming scientific evidence is that this precise quantitative value of slowing or stopping human-caused climate change is wrong. The future costs associated with climate change that could be avoided are not zero.
In the analysis below we combine the quantitative information that is available with expert judgement to produce estimates of the likely economic costs associated with climate change in Montana if no public policy steps are taken to reduce human GHG emissions. That expert judgement is tied to a half-century of experience analyzing the Montana economy, the role that natural and social amenities have contributed to economic vitality in Montana, and long run economic costs of projected climate change in Montana are far more reliable and accurate than the explicit alternative assumption that there are no costs at all associated with that ongoing climate change in Montana.
4. Losses in Grain Crops and Cattle Raising
Warmer springs and the delay in the first hard frost in the fall might be interpreted to mean that Montana will face a longer growing season. Since carbon dioxide (CO2) in the atmosphere is a crucial input to plant photosynthesis, high concentrations of CO2 could also be seen as productive “fertilizer” for crops and forage for cattle on rangelands.
This is unlikely to be the case. The seasonal pattern of changes in temperatures and precipitation will favor rapid growth of plants in the spring and then hot dry summers that severely stress the plants. In addition, the carbon in the atmosphere has to combine with nitrogen in the soil to produce high yields of nutritious plants. As discussed in this report nitrogen depletion may prevent this. In addition the hot, dry weather and increased CO2 concentrations will favor invasive species and plants unpalatable to livestock. The desiccation of early, fast-growing plants will increase rangeland wildfires, which, in turn, will encourage a degradation of the vegetation on rangeland for cattle. Similar problems will occur with grain production with spring wheat harvested in the fall being initially hardest hit by the hot dry summers. Winter wheat ultimately will also be negatively impacted.
The economic impact of these consequences of climate change on Montana’s two primary agricultural sectors is projected to be a 20 percent decline in rangeland cattle production and a 25 percent reduction in grain production. The economic losses associated with this aspect of climate change would be the loss of about 25,000 jobs and $736 million in labor earnings by mid-century.
