Welfare impact of climate change on capture fisheries in Vietnam

Based on the Eqs (6–9), the changes in social welfares by 2035 and 2065 are calculated. Since the potential catch is negatively affected by climate change, in Eq (6), we have 0 < b < 1. The value of b is estimated as followings: By 2035, b2(0.66, 0.91) for RCP4.5; b2(0.63, 0.86) for RCP8.5; By 2065, b2(0.43, 0.81) for RCP4.5; b2(0.36, 0.70) for RCP8.5. Now we will consider the dynamics of consumer and producer welfares in different fishery demand scenarios, i.e., changing parameter a in Eq (5). a = 1, i.e., demand remains unchanged. With the expansion of aquaculture, the substi- tute effect might offset the demand increase due to either growing population, improving income or changing preferences. For ease of analysis, we start with the assumption that the demand for capture products remains unchanged, i.e., a = 1. Fig 4 presents the welfare changes of fishery consumers and producers due to climate change by 2035 and 2065, relative to 2018. The social discounted rate of 2% per year is applied as suggested by Drupp, Freeman [83] for the climate change context. Fig 4 shows that producer surplus is positive and consumer surplus is negative in all RCPs. Consumer loss is from 7 to 9 billion USD per year at the mean projection of RCPs 4.5 and 8.5. By 2065, consumer loss is from 10 to 18 billion USD. Calculations for Eqs (8) and (11) show that the capture reduction leads to a double price increase in 2035 and 3–5 times in 2065 compared to 2018. Fisher profit increases 1.7–1.9 times in 2035 and 2.7–4.2 times in 2065, depending on climate change scenarios. As depicted in Fig

4, by 2035, producer gain is from 3.5 to 4.5 billion USD per year in RCPs 4.5 – 8.5. This amount equals 30%–40% of the total capture value in 2018, approximately 12 billion USD in PPP [3]. By 2065, the gain is from 5 to 9 billion USD in RCPs 4.5 – 8.5. Fig 3. Potential decrease in capture yield due to climate change relative to 2018. https://doi.org/10.1371/journal.pone.0264997.g003 PLOS ONE Welfare impact of climate change on capture fisheries in Vietnam PLOS ONE | https://doi.org/10.1371/journal.pone.0264997 April 25, 2022 11 / 20