We examine the abatement investment and pricing decisions within a supply chain where consumers prioritize environmental performance. The product's green reputation is influenced by the gap between its unit pollution rate and an industry standard that declines over time. The abatement capacity investment is managed by the manufacturer, but the retailer has the option to share the associated cost. Our findings reveal that cost-sharing cooperation achieves an economically Pareto-optimal outcome compared to the no-cost-sharing scenario. From an environmental perspective, while it encourages greater abatement capacity investment and lowers the unit pollution rate, in most cases, the associated increase in demand may counteract these benefits, potentially leading to higher total emissions. Furthermore, as the industry standard declines more rapidly, firms tend to reduce their abatement investments. Lastly, firms with lower initial green reputation or abatement capacity -- the ­"brown firms" -- are less likely to catch up with the evolving standard, as higher initial states drive a virtuous cycle of increased investment, enhanced abatement capacity, reduced emissions, and further goodwill gains.