結合產業特性與TESG評級探討碳排放量之價值攸關性

Abstract

本論文旨在探討市場是否會根據產業特性來評估碳排放量對公司價值的影響,同時檢視ESG評級是否能提升碳排放量的資訊價值。研究對象為2015年至2022年的臺灣非金融業上市櫃公司,依據產業特性將樣本分類為高碳排產業(水泥、造紙、電子、鋼鐵、石化與紡織業)與非高碳排產業,並採用TESG等級與TESG分數作為ESG評級的指標。本論文參考Griffin et al.(2011)的碳排放量估計模型,以樣本期間有揭露碳排公司的碳排放量,來估計未揭露碳排公司的碳排放量,接著,以Ohlson(1995)的評價模型為基礎建立一系列碳排放量評價模型,以探討碳排放量的價值攸關以及ESG評級的調節作用。 實證結果顯示,在高碳排產業中,碳排放量對公司價值有顯著的負向影響,且市場對碳排放的負面評價於揭露與未揭露碳排之公司樣本間皆同樣顯著,顯示碳排放被視為一種未認列的環境負債,尤其是碳排放量較高的產業,另外也暗示即使是未揭露碳排放資訊的公司,市場依然會基於可獲得的其他資訊來推測其碳排放情況,並對公司價值進行調整。在非高碳排產業中,碳排放量對公司價值則有顯著的正向影響,且市場對碳排放的正面評價於揭露與未揭露碳排之公司樣本間皆同樣顯著,這一現象的可能原因可以從成本效益考量、碳管制規範進程、投資者觀念以及政府宣導等方面來解釋。 除此之外,不論產業為何,在未揭露碳排放資訊的公司中,較高的TESG等級與TESG分數對碳排放量之股價影響有較大的正向調節效果,本論文推測可能的原因為ESG評級補足了未揭露的碳排放資訊,並同時顯示較高的ESG評級代表具備較佳的風險管理與可持續發展能力,投資者信任這些公司在未來將採取措施降低其碳排放量或是能提升其能源使用效率,以致於越高的TESG等級與TESG分數越能夠正向調節未揭露碳排資訊公司碳排放量對公司價值的影響。最後,本論文發現相較於TESG等級,TESG分數作為一個更詳細的量化指標,能更有效地捕捉碳排放量如何影響公司價值,以及ESG評級如何調節碳排放量對公司價值的影響。

This study aims to explore whether the market assesses the impact of carbon emissions on firm value based on industry characteristics and to examine whether ESG ratings enhance the value of carbon emissions information. The study focuses on non-financial listed companies in Taiwan from 2015 to 2022, categorizing the samples into high carbon-emitting industries (cement, paper, electronics, steel, petrochemicals, and textiles) and non-high carbon-emitting industries. It utilizes TESG levels and TESG scores as indicators of ESG ratings. The study adopts the carbon emissions estimation model proposed by Griffin et al. (2011) to estimate the emissions of companies that do not disclose their carbon emissions information during the sample period. Furthermore, it establishes a series of carbon emissions valuation models based on Ohlson (1995) to explore the value relevance of carbon emissions and the moderating effect of ESG ratings. The empirical results show that in high carbon-emitting industries, carbon emissions have a significant negative impact on firm value, and the market’s penalty for carbon emissions does not vary with the disclosure of information, indicating that carbon emissions are viewed as an unrecognized environmental liability, especially in industries with higher emissions. The results also suggest that for companies that do not disclose carbon emissions information, the market still estimates their emissions through other available sources and adjusts their firm value accordingly. In contrast, in non-high carbon-emitting industries, carbon emissions have a significant positive impact on firm value, and this positive market valuation is similarly significant among companies regardless of disclosure. Possible explanations for this phenomenon include cost-benefit considerations, the stage of carbon regulation, investor perceptions, and government advocacy. Moreover, regardless of the industry, in companies that do not disclose carbon emissions information, higher TESG levels and TESG scores have greater positive moderating effects on the impact of carbon emissions on stock prices. The study speculates that the possible reason is that ESG ratings supplement the undisclosed carbon emissions information. At the same time, higher ESG ratings signify better risk management and sustainability development capabilities. Investors trust that these companies will take measures to reduce their carbon emissions or improve their energy efficiency in the future. Finally, this study finds that compared to TESG levels, TESG scores, as a more detailed quantitative indicator, can more effectively capture how carbon emissions affect firm value and how ESG ratings moderate the impact of carbon emissions on firm value.