Gender, Critical Mass and Carbon Emission

Abstract

This study investigates the impact of board gender diversity and the presence of a critical mass of female directors on corporate carbon emissions. Grounded in agency, legitimacy, and critical mass theories, it explores how the gender composition of corporate boards shapes firms’ environmental governance. Using panel data from 37 non-financial CAC 40 firms between 2020 and 2023, the analysis employs Fixed Effect regression models with robustness checks. The results reveal a non-linear relationship between gender diversity and emissions: a higher proportion of female directors reduces emissions only when the board reaches a critical mass, supporting the idea that women’s influence becomes significant beyond token representation. CEO duality negatively affects environmental outcomes, while firm size and profitability are positively associated with emission performance. The study contributes to corporate governance research by showing that meaningful female representation enhances environmental accountability, highlighting the need for policies promoting gender balance and sustainability-oriented board practices.

1. Introduction

The relationship between board gender diversity and corporate environmental performance, particularly in terms of carbon emissions, has attracted increasing scholarly attention over the past decade. Research in this domain is rooted in the broader fields of corporate governance and sustainability, emphasizing how board composition shapes strategic decision-making, risk management, and ethical conduct.

In recent years, the escalating urgency of climate change and the growing demand for corporate accountability have placed environmental performance and transparency at the center of governance debates. Investors, regulators, and other stakeholders now expect firms not only to disclose their carbon emissions but also to implement effective strategies for reducing them.

Corporate governance mechanisms, particularly board composition, are now widely recognized as critical determinants of sustainability strategies and environmental outcomes (Benlemlih & Yavaş, 2024).

Within this context, corporate boards play a decisive role in defining firms’ sustainability agendas and overseeing their environmental practices.

Among various governance attributes, board gender diversity has emerged as a crucial determinant of sustainability-oriented leadership.

Prior research suggests that female directors tend to enhance board monitoring, ethical awareness, and stakeholder orientation, which may contribute to improved environmental performance and reduced carbon emissions (Farooq et al., 2023).

However, empirical findings remain mixed, as some studies report a negative relationship between gender diversity and emissions, while others find weak or insignificant effects once firm-specific and institutional factors are controlled for (Nuber & Velte, 2021; Shakil et al., 2026).

One important explanation for these inconsistent findings lies in the concept of critical mass. According to critical mass theory (Kanter, 1977), minority groups can exert meaningful influence only when their representation reaches a certain threshold.

In corporate boards, the presence of one or two women may lead to tokenism, limiting their ability to influence strategic decisions. In contrast, when a sufficient number of female directors is achieved, their collective voice can significantly shape board dynamics and sustainability outcomes (Torchia et al., 2011; Joecks et al., 2013).

However, despite its theoretical relevance, the moderating role of critical mass in the relationship between board gender diversity and carbon emissions remains underexplored, particularly in the European context. While some studies report a positive association between the proportion of female directors and the level of carbon disclosure (Post et al., 2011, Liao et al., 2015, Tingbani et al., 2020), few studies indicate no impact of female directors on environmental out-puts (Birindelli et al., 2019) or on carbon issues in particular (Kılıç & Kuzey, 2019; Prado-Lorenzo & Garcia-Sanchez, 2010). Furthermore, existing studies have largely focused on environmental disclosure rather than actual carbon emission performance (Jizi et al., 2014; Fernández-Gago et al., 2018), leaving a gap in understanding how board characteristics influence real environmental outcomes.

This limitation is particularly relevant in the context of increasing regulatory pressure in Europe, including frameworks such as the Corporate Sustainability Reporting Directive (CSRD), which emphasize both transparency and measurable environmental performance.

Specifically, the study investigates whether the relationship between gender diversity and carbon emissions is nonlinear and contingent upon reaching a threshold level of female representation.

This study focuses on carbon emissions as a measure of environmental performance, rather than carbon disclosure, which reflects reporting practices. It aims to contribute to the growing literature: First, it extends corporate governance research by providing empirical evidence on the nonlinear relationship between board gender diversity and carbon emissions, highlighting the importance of critical mass.

Second, it shifts the focus from environmental disclosure to actual emission performance, offering a more direct assessment of firms’ environmental impact.

Third, it provides new evidence from the French context, where regulatory frameworks promoting gender diversity and sustainability are particularly advanced.

From a practical perspective, the findings offer important implications for policymakers and regulators by emphasizing that symbolic gender diversity is insufficient.

Instead, achieving a meaningful level of female representation is necessary to enhance environmental governance and reduce emissions.

The results also provide insights for investors and corporate decision-makers regarding the strategic importance of board composition in addressing climate-related risks.

Methodologically, the study relies on a panel dataset of 37 non-financial CAC 40 firms over the period 2020–2023. Using Fixed Effects regression models and robustness checks, the analysis examines both the direct effect of gender diversity and the threshold effect associated with critical mass.

The findings reveal a nonlinear relationship: board gender diversity contributes to lower carbon emissions only when a critical mass of female directors is reached.

The remainder of the paper is organized as follows. The theoretical background and relevant research hypotheses are presented in Section 2. Section 3 explains the methodology employed in this study, while the results are presented in Section 4. The robustness test is shown in Section 5 and the conclusions in Section 6.

2. Literature Review and Hypothesis Development

The link between board characteristics and corporate environmental outcomes has been widely examined in corporate governance literature. Among these attributes, board gender diversity has received growing attention as a potential driver of sustainability performance and carbon emission management. Drawing on agency, legitimacy, and critical mass theories, prior studies suggest that the presence of female directors can influence board monitoring effectiveness, ethical orientation, and strategic priorities toward environmental responsibility (Adams & Ferreira, 2009; Post et al., 2011; Liao et al., 2015; Ben-Amar et al., 2017). However, empirical evidence remains mixed, with some studies reporting positive associations between female board representation and environmental outcomes, while others find insignificant or even negative effects. This inconsistency highlights the need to further explore the conditions, such as the attainment of a critical mass, under which gender diversity effectively contributes to improving corporate environmental performance.

2.1. Presence of Female and Carbon Emission

Board Gender Diversity (BGD) refers to the proportion or presence of female directors on the board, and it is increasingly viewed as a key determinant of ethical, transparent, and sustainability-oriented decision-making (Bear et al., 2010; Post et al., 2011; Cordeiro et al., 2020).

First, agency theory suggests that diverse boards enhance monitoring effectiveness and reduce managerial opportunism. Female directors are often found to be more diligent and risk-averse, leading to stronger oversight of environmental practices and greater emphasis on long-term value creation (Adams & Ferreira, 2009; Liao et al., 2015).

Second, stakeholder and legitimacy theories argue that women directors are more sensitive to stakeholder expectations and societal pressures, particularly regarding environmental responsibility. This heightened awareness may encourage firms to adopt more transparent and proactive carbon reduction strategies (Liao et al., 2015; Ben-Amar et al., 2017).

Third, insights from social role theory suggest that women are generally more inclined toward ethical behavior and sustainability concerns, which can influence boardroom discussions and strategic priorities toward environmentally responsible actions (Biswas et al., 2022).

Several recent studies report that higher female representation on boards is associated with greater carbon disclosure and lower greenhouse-gas intensity, supporting the claim that gender-diverse boards can drive emission-reduction strategies (Bouaddi et al., 2023; Ali et al., 2024).

Empirical studies have provided evidence supporting this view. For instance, Liao et al. (2015) found that the proportion of women on the board was positively associated with the likelihood and quality of greenhouse gas (GHG) disclosure among UK firms. Similarly, Ben-Amar et al. (2017) reported that female directors significantly improved firms’ environmental disclosure quality in Canada. These findings suggest that female board participation enhances board monitoring and ethical standards, leading to greater environmental transparency.

More recent studies further confirm this relationship. Benlemlih and Yavaş (2023) and Hossain et al. (2023) report that firms with higher female board representation tend to exhibit lower carbon intensity and improved environmental performance. Likewise, Ali et al. (2024) provide evidence that gender diversity positively influences sustainability outcomes through improved governance quality.

However, despite this growing evidence, the relationship remains inconclusive in some contexts, suggesting that the effectiveness of gender diversity may depend on additional conditions, such as the level of female representation or institutional factors.

While board gender diversity may affect environmental decisions, its influence may also depend on unobservable firm characteristics. El Moujahid et al. (2025) suggest that firm culture can shape governance outcomes and strategic choices, potentially influencing how female directors affect carbon-related decisions.

Based on these theoretical arguments and empirical findings, this study proposes the following hypothesis:

H1a. 

Board gender diversity is negatively associated with the level of carbon emission.

While the presence of female directors may promote environmental transparency, their actual influence often depends on reaching a sufficient level of representation. The critical mass theory (Kanter, 1977) posits that minorities within decision-making groups can only exert meaningful influence when they reach a threshold proportion, generally around 30%. Below this level, women directors may be perceived as symbolic appointments (“tokens”) with limited ability to challenge established board norms or influence strategic agendas.

In the context of corporate governance, critical mass has been identified as a decisive factor that transforms women’s presence from symbolic to substantive (Torchia et al., 2011). When a critical mass of women is achieved, gender diversity facilitates open dialog, increases mutual support among female directors, and enables them to advocate effectively for sustainability-related initiatives (Joecks et al., 2013; Terjesen et al., 2016).

Empirical evidence reinforces this theoretical argument. Studies show that boards with three or more women directors are more likely to exhibit proactive environmental strategies, and improved sustainability performance (Post et al., 2011; Harjoto et al., 2015). Conversely, boards with only one or two women often show limited change in reporting behavior or decision outcomes, as female voices remain underrepresented and socially constrained (Bear et al., 2010). Omenihu et al. (2025) study the relation between Board Gender Diversity and Environmental, Social, and Governance (ESG) Disclosure in Developed Countries. Her study of European listed firms (2012–2023) uses IV-GMM estimation and finds that firms with at least three female directors demonstrate greater ESG disclosure; conversely, boards with only one or two women show negative effects. Shakil et al. (2026), using European data (2016–2022), find a non-linear relationship: carbon emissions performance improves with board gender diversity up to ~35%, with a minimum threshold around ~22%.

Hence, the effectiveness of board gender diversity in driving environmental disclosure may depend on whether the board has achieved a critical mass of female directors. Based on these theoretical and empirical arguments, the following hypothesis is proposed:

H1b. 

The relationship between board gender diversity and corporate carbon emissions becomes significant only when a critical mass of female directors is reached.

2.2. Board Independence and Carbon Emission

Board independence, the proportion of non-executive or outside directors, is a fundamental mechanism in corporate governance that enhances oversight and accountability. In the context of environmental sustainability, independent directors are expected to ensure responsible environmental strategies, transparency, and compliance with carbon reduction goals.

Empirical evidence generally supports a negative relationship between board independence and corporate carbon emissions. Independent directors strengthen monitoring and reduce managerial opportunism, encouraging long-term strategic decisions that align with environmental objectives (De Villiers & Staden, 2011). As they are detached from daily management, independent board members promote transparency, improve disclosure quality, and advocate for sustainable investments (Armstrong et al., 2014). Recent studies confirm that firms with more independent directors tend to achieve lower carbon emission levels. For instance, Guo et al. (2024) and Mansour (2025) find that independent boards significantly enhance carbon disclosure and mitigate emission intensity, particularly when complemented by sustainability committees. Likewise, Wahyuningrum et al. (2025) and Khlif and Souissi (2023) report that independent directors foster stronger environmental accountability in emerging markets. However, some studies (Walls et al., 2012; Yu & Zheng, 2022) note that this effect weakens when independent directors lack environmental expertise or undervalue executive insight. Overall, board independence contributes to lower carbon emissions when accompanied by environmental knowledge and institutional support.

Drawing on these arguments, we propose the following hypothesis:

H2. 

Board independence is negatively associated with corporate carbon emissions.

2.3. CEO-Duality and Carbon Emission

The relationship between CEO duality and carbon emissions has been widely debated in corporate governance research. From an agency theory perspective, CEO duality concentrates power in one individual, weakening board oversight and reducing accountability, which may lead to less commitment to environmental initiatives and higher carbon emissions (Jensen & Meckling, 1976; Krause et al., 2014). Empirical evidence supports this view: Zhang et al. (2023) and Nguyen and Pham (2024) find that firms where the CEO also chairs the board tend to disclose less environmental information and exhibit greater carbon intensity. Conversely, proponents of stewardship theory argue that CEO duality can facilitate faster decision-making and coherent strategic direction, which may enhance sustainability performance when CEOs are environmentally oriented (Donaldson & Davis, 1991). Recent findings suggest that CEO duality may positively affect carbon performance when paired with strong governance mechanisms or sustainability committees.

H3. 

CEO duality is associated with lower corporate carbon emissions.

3. Research Design

3.1. Sample Selection

This study focuses on firms listed on the CAC 40 index, representing the largest and most actively traded companies on the Euronext Paris Stock Exchange. The sample covers the period 2020 to 2023. The study period is justified by several factors. First, it reflects a period of increased regulatory and stakeholder pressure on firms to enhance carbon transparency and environmental performance, particularly in Europe with the development of sustainability reporting frameworks such as the Corporate Sustainability Reporting Directive (CSRD). Second, this timeframe captures the growing integration of ESG considerations into corporate governance following recent global challenges, including the COVID-19 pandemic. Finally, the selected period ensures better data availability and consistency in carbon emissions reporting, improving the reliability of the empirical analysis.

Data on corporate governance attributes such as, board independence, board size, gender diversity, and CEO duality, were collected from companies’ annual reports. Information on carbon emissions (Scopes 1 and 2) was obtained from Carbon Disclosure Project (CDP) datasets. Financial variables, including firm size, leverage, and performance, were sourced from Datastream database. Financial firms were excluded. The final sample consists of 37 firms, yielding 148 firm-year observations.

3.2. Measurement of Variables

Table 1. Definition and of measurement variables.

Variables	Definitions	Measurement
GHG Emission	Corporate greenhouse gas emissions (Scope 1 and Scope 2)	Natural logarithm of (scope 1 + scope2 + 1)
FEMALE	Female representation in the Board	Number of women in the board of directors
FEMALE PROPORTION	Female representation in the Board	Percentage of female on the board
FEMALE ≥ 4	Female representation in the Board	Dummy variable equal to 1 when the board includes at least four female directors and 0 otherwise.
FEMALE ≥ 5	Female representation in the Board	Dummy variable equal to 1 when the board includes at least five female directors and 0 otherwise.
FEMALE ≥ 6	Female representation in the Board	Dummy variable equal to 1 when the board includes at least six female directors and 0 otherwise.
FEMALE ≥ 7	Female representation in the Board	Dummy variable equal to 1 when the board includes at least seven female directors and 0 otherwise.
FEMALE ≥ 8	Female representation in the Board	Dummy variable equal to 1 when the board includes at least eight female directors and 0 otherwise.
FEMALE ≥ 9	Female representation in the Board	Dummy variable equal to 1 when the board includes at least nine female directors and 0 otherwise.
BIND	Degree of board independence	Percentage of non-executive directors on the board
DUALITY	CEO also serving as board chair	Dummy variable: 1 if CEO = Chair, 0 otherwise
ROA	Firm financial performance	Net profit/total assets
F-SIZE	Size of the firm	Natural logarithm of (Total Assets)
LEV	Firm’s financial leverage.	Total Liabilities/Total Assets

provides detailed definitions and measurements of all variables used in this study. The operationalization of these variables is consistent with prior literature in corporate governance and environmental performance, thereby enhancing the comparability and robustness of the empirical findings.

The dependent variable, GHG Emissions, serves as a proxy for corporate carbon emissions and is defined as the total amount of direct (Scope 1) and indirect (Scope 2) greenhouse gas emissions. Scope 3 emissions are excluded due to limited data availability and significant inconsistencies in reporting practices across firms (Downie & Stubbs, 2013). To minimize data heterogeneity that may arise from scaling absolute emissions by financial or operational outputs, the study employs the natural logarithm of emissions intensity as thew dependent variable (Benlemlih & Yavaş, 2023; Downar et al., 2021; Hossain et al., 2023; Yu et al., 2023). The key independent variable is Board Gender Diversity (BGD), captured through three measures. First, the number of female directors on the board is used as a continuous indicator (Kumar and Kapil, 2024). Second, like El Moujahid et al. (2025), we use the percentage of female directors on board. Third, to assess the critical mass effect, six binary variables are constructed to identify boards with at least four, five, six, seven, eight, or nine female members.

Additional governance variables are included to control for board characteristics. Like Khlif and Souissi (2023), board Independence is calculated as the percentage of non-executive directors relative to total board size. A higher level of independence is expected to strengthen oversight, reduce agency conflicts, and encourage sustainable, long-term investment (De Villiers & Staden, 2011). CEO Duality (Duality) is represented by a dummy variable equal to 1 when the CEO also serves as the board chair and 0 otherwise. Consistent with prior literature (Haque, 2017), dual leadership structures may weaken monitoring effectiveness and reduce environmental performance due to concentrated decision-making power.

Firm-level control variables are also incorporated. Leverage (LEV), defined as total liabilities divided by total assets Hossain et al. (2023), captures firm risk. Firm Size (F-SIZE), measured as the natural logarithm of total assets (Ali et al., 2024) is included because larger firms generally produce higher absolute emissions yet often exhibit greater transparency in carbon reporting due to heightened regulatory scrutiny and stakeholder pressure. Return on Assets (ROA) measures financial performance, (Luo et al., 2022).

3.3. Model Specification

To examine the influence of board attributes and critical mass on carbon emissions, the study employs a panel data regression model. The dependent variable is the logarithm of carbon emissions, representing the firm’s greenhouse gas emissions performance.

The three primary methods of estimation that can be employed in panel data analysis are pooled ordinary least squares (POLS), fixed effects (FE) regression, and random effects (RE) regression (Mack et al., 2024). Wooldridge (2012) asserts that the pooled ordinary least squares method regards the panel dataset as a singular extensive cross-section. This method assumes that all observations are independent and ignores any potential underlying structure in the data. However, when there is unobserved heterogeneity present, the estimates are inefficient and biased. On the other hand, the FE and RE models explicitly acknowledge that identical entities (example: firms) are present across various time periods, thereby controlling unobserved heterogeneity specific to the entities. Unobserved heterogeneity refers to intrinsic characteristics specific to each firm that remain constant over time but are not explicitly measured within the model (Hsiao, 2005). Factors such as board composition, environmental performance and other unique characteristics of the firm may skew the estimation results if not adequately controlled.

Although the fixed-effects model mitigates bias from time-invariant unobserved heterogeneity, potential endogeneity concerns such as reverse causality may persist. Future research could employ dynamic panel techniques (for example system GMM) to further address these issues.

To determine the most suitable estimation technique, we performed the Hausman specification test, which assesses whether the fixed effects model or the random effects model yields more reliable estimates (Hsiao et al., 2002).

The Hausman test was conducted. The results (χ² = 13.15, p = 0.0407) reject the null hypothesis, indicating that the random effects estimator is inconsistent. Therefore, we employed fixed effects in our regression analysis. Thus, we employed the fixed effects regression model in our empirical analysis. So, the baseline model is specified as follows:

$${\mathrm{GHG}}_{it}={\beta }_1{\mathrm{FEMALE}}_{it}+{\beta }_2{\mathrm{BIND}}_{it}+{\beta }_3{\mathrm{DUALITY}}_{it}+{\beta }_4{\mathrm{ROA}}_{it}+{\beta }_5{\mathrm{LEV}}_{it}+{\beta }_6{\mathrm{F}\text{-}\mathrm{SIZE}}_{it}{+{\alpha }_i+{\gamma }_t+\mathcal{E}}_{it}$$

(1)

where ${\mathrm{GHG}}_{it}$ denotes the logarithm of carbon emissions for firm i in year t; ${\mathrm{FEMALE}}_{it}$ represents board gender diversity; ${\mathrm{BIND}}_{it}$ captures board independence; and ${\mathrm{DUALITY}}_{it}$ indicates whether the CEO also serves as board chair. ${\mathrm{ROA}}_{it}$, ${\mathrm{LEV}}_{it}$, and ${\mathrm{F}\text{-}\mathrm{SIZE}}_{it}$ denote firm profitability, leverage, and firm size, respectively. where ${\alpha }_i$ captures unobserved firm-specific effects, ${\gamma }_t$ controls for year-specific shocks and ${\mathcal{E}}_{it}$ is the error term.

After estimating the model, we need to check whether the assumptions underlying the regression are satisfied. Autocorrelation and heteroskedasticity are violations of these assumptions, and their presence can affect the validity of our inference. We evaluate the presence of heteroscedasticity and autocorrelation using Modified Wald test (χ² = 5,100,227.34, p = 0.0000).

Since heteroscedasticity is detected in our estimation results, we employ robust standard errors.

To test the critical mass effect of female directors, an alternative specification replaces ${\mathrm{FEMALE}}_{it}$ with binary variables representing boards having at least four, five, six, seven, eight, or nine women directors.

The expected signs of the coefficients are guided by agency and stakeholder theories. A negative relationship is anticipated between presence of woman in board and carbon emissions, as gender-diverse boards are expected to promote sustainability. Board independence is also expected to reduce emissions through enhanced monitoring and accountability. In contrast, CEO duality is predicted to increase emissions due to weakened governance and concentrated decision-making authority.

4. Results

4.1. Descriptive Statistics

Table 2. Descriptive statistics.

	Mean	Std. Deviation	Minimum	Maximum
GHG Emission	15.39911	2.554184	9.955653	20.66353
FEMALE	6.168919	1.522567	3	11
FEMALE PROPORTION	0.4779943	0.0580344	0.4	0.6875
BIND	0.5885	0.1765	0.25	1
DUALITY	0.4189189	0.4950574	0	1
ROA	0.0531165	0.0795798	−0.163	0.693
F-SIZE	17.75759	1.250432	14.22164	23.18405
LEV	0.5727965	0.1723479	0.1474983	0.9413598

Note: All variables are as defined in Table 1.

presents the descriptive statistics for the main variables used in this study. The average number of female directors (FEMALE) is 6.16, with a minimum of 3 and a maximum of 11, suggesting moderate gender representation on French corporate boards. The average of female proportion (FEMALE PROPORTION) on boards is approximately 47.8%, suggesting a relatively high level of gender representation within the sampled firms. The relatively high proportion of female directors observed in the sample (min 40%) can be explain by institutional developments of the Copé–Zimmermann Law in France, which introduced mandatory gender quotas for corporate boards. Board independence (BIND) has a mean of 0.5585 implying that, on average, 55.85% of board’s members are independent directors. Regarding CEO duality (DUALITY), approximately 42% of firms combine the roles of CEO and board chair, as shown by the mean value of 0.42.

The average board size (B-SIZE) is 13.39 members, ranging from 6 to 20, which reflects the relatively large governance structures of CAC 40 firms.

The observed board size and composition are also consistent with the regulatory environment in France, particularly following the Copé–Zimmermann Law, which mandates a minimum representation of 40% of each gender on boards of large listed firms. This regulation has contributed to increasing board size and diversity, as firms adjust their composition to comply with gender quotas while maintaining a balance of expertise and independence.

Moreover, prior studies on French firms (Nekhili & Gatfaoui, 2013) report similar board structures, confirming that large boards with a substantial number of independent directors are common among CAC 40 companies. This institutional context supports the interpretation that the descriptive statistics reported in this study are representative of standard governance practices in France.

In terms of firm characteristics, the mean ROA is 0.053, indicating an average profitability of about 5.3%. The firm size (F-SIZE) variable shows a mean value of 17.76, consistent with the large scale of companies in the index. Lastly, the leverage ratio (LEV) averages 0.57, with a minimum of 0.15 and a maximum of 0.94, suggesting considerable variation in capital structures across the sample. Overall, these descriptive statistics confirm that the sample exhibits sufficient variability to test the hypothesized relationships between board characteristics and carbon emission performance.

To examine the potential for multicollinearity among explanatory variables, Pearson’s correlation matrix was evaluated in

Table 3. Correlation matrix.

	FEMALE	BIND	DUALITY	ROA	F-SIZE	LEV
FEMALE	1.0000
BIND	0.0925	1.0000
	0.2633
DUALITY	0.0353	0.0427
	0.6698	0.6066
ROA	−0.0108	−0.1510 *	−0.0579	1.0000
	0.8966	0.0670	0.4846
F-SIZE	0.0938	0.1117	0.1803 **	−0.1818 **	1.0000
	0.2569	0.1766	0.0283	0.0270
LEV	−0.0913	0.1429 *	0.0271	−0.2299 ***	0.0058	1.0000
	0.2695	0.0831	0.7436	0.0049	0.9446

Note: *, **, and *** represents statistical significance at the 10%, 5% and 1% level respectively. All variables are as defined in Table 1.

. The correlations are generally low to moderate, suggesting that multicollinearity is unlikely to pose a significant concern. To ensure that multicollinearity does not bias the regression estimates, we conducted a Variance Inflation Factor (VIF) analysis for all explanatory variables. The results indicate that all VIF values are well below the commonly accepted threshold of 10.

4.2. Multivariate Regression Analysis

Table 4. Female board representation and carbon emissions.

	Model (1)	Model (2)
FEMALE	−0.0881956 **
	0.025
FEMALE PROPORTION		−4.5231118 **
		0.043
BIND	0.0261825	0.0192524
	0.415	0.804
DUALITY	−0.6943369 **	−0.6497635 *
	0.050	0.073
ROA	1.00973 **	1.121741 *
	0.037	0.066
F-SIZE	0.3260432 **	0.3341426 **
	0.030	0.035
LEV	2.615023 *	2.498089 *
	0.081	0.074
R2	0.3242	0.3332
Number of obs.	148	148

Note: * and **, represents statistical significance at the 10% and 5% level respectively. All variables are as defined in Table 1.

and

Table 5. Female board representation, critical mass, and carbon emissions.

	Model (3)
	(a)	(b)	(c)	(d)	(e)	(f)
FEMALE ≥ 4	−0.2146226
	0.569
FEMALE ≥ 5		−0.553919
		0.338
FEMALE ≥ 6			−0.2542597 **
			0.038
FEMALE ≥ 7				−1.397036 *
				0.052
FEMALE ≥ 8					0.0581633
					0.701
FEMALE ≥ 9						0.3824618 **
						0.049
ROA	0.9252657 **	1.06593 **	1.055661 **	1.00973 **	1.034079 **	0.9936613 **
	0.035	0.035	0.027	0.036	0.036	0.040
F-SIZE	0.3441009 **	0.3088689 **	0.3102406 **	0.3260432 **	0.3341426 **	0.3271381
	0.026	0.046	0.044	0.039	0.035	0.030 **
LEV	2.605442 *	2.591915 *	2.64215 *	2.615023 *	2.498089 *	2.624484 *
	0.081	0.086	0.082	0.081	0.074	0.081
R2	0.3385	0.3406	0.3251	0.3242	0.3332	0.3296
Number of obs.	148	148	148	148	148	148

Note: * and **, represents statistical significance at the 10% and 5% level respectively. All variables are as defined in Table 1.

present the results of regression analyses examining the effect of board gender diversity on firms’ carbon emissions. The dependent variable is the natural logarithm of greenhouse gas (GHG) emissions intensity. Model (1) includes the number of female directors, Model (2) examines the proportion of female on the board, while Model (3) incorporates the critical mass indicators (≥4FEMALE to ≥9FEMALE) representing boards with at least four, five, six, seven, eight, or nine female members, respectively. The operationalization of critical mass in this study relies on dummy variables capturing threshold levels of female representation on corporate boards. This approach is consistent with prior empirical studies, such as Liu et al. (2014) and Srivastava et al. (2018), which use binary or threshold-based measures to capture the increasing influence of female directors once a certain level is reached. Such an approach is particularly suitable for testing critical mass theory, which emphasizes the existence of influence thresholds rather than linear effects.

Moreover, descriptive statistics indicate that the average number of female directors is 6.168919, with a mean of board size of 13.35, representing approximately 47% of board members. This suggests that the sample includes boards with substantial female representation, meaning that the chosen thresholds capture meaningful variations in gender diversity and are not merely symbolic.

While the theoretical literature often defines critical mass in proportional terms (around 30% female representation), the relatively homogeneous board sizes observed in the sample reduce the risk of misinterpretation associated with absolute measures. Therefore, the binary specification remains a relevant and interpretable proxy for capturing threshold effects in line with critical mass theory. Nevertheless, the results should be interpreted with caution, and future research may consider proportion-based measures to further validate these findings.

In Model (1), the coefficient for FEMALE is negative and statistically significant at the 5% level (−0.0882, p = 0.025). This indicates that a higher proportion of women on the board is associated with lower carbon emissions, supporting the view that female directors enhance environmental oversight and sustainability-oriented governance. However, the results should be interpreted as associations in lieu of strict causal effects, as firms with stronger environmental commitments may also be more likely to appoint female directors. Such a negative association can be interpreted through tokenism theory (Kanter, 1977), which suggests that when women remain a small minority on boards, their influence is constrained and often symbolic. This finding contrasts with earlier studies that found a positive association between gender diversity and environmental reporting (Liao et al., 2015; Ben-Amar et al., 2017) but aligns with recent evidence suggesting that gender diversity’s benefits materialize only beyond a threshold (Ali et al., 2024; Omenihu et al., 2025).

Regarding DUALITY (CEO duality), the coefficient is negative and significant (−0.694, p = 0.050), suggesting that when the CEO also serves as board chair, firms tend to have lower carbon emissions, possibly reflecting stronger centralized decision-making or better strategic alignment. BIND (board independence) is positive but not significant, implying that independent directors alone do not exert a meaningful influence on emissions performance.

The adjusted R² = 0.324 demonstrates a reasonable explanatory power for governance-based disclosure models.

In Model (2), the coefficient of FEMALE PROPORTION is negative and statistically significant, suggesting that a greater proportion of women on boards is associated with lower carbon emissions. This result reinforces the notion that relative representation matters in addition to the absolute number of women directors. The consistency of negative coefficients across both models strengthens the robustness of the findings and suggests that the environmental effect of women directors persists regardless of whether female representation is measured in absolute or proportional terms.

To explore whether the impact of women directors depends on their number, Model (3) introduces dummy variables for boards with at least four to nine female members. The results reveal that the effect of female board representation varies according to the critical-mass threshold adopted. The coefficients for FEMALE ≥ 4 and FEMALE ≥ 5 are negative but insignificant, suggesting limited influence when women remain below a critical mass.

Interestingly, FEMALE ≥ 6 (β = −0.254, p = 0.038) and FEMALE ≥ 7 (β = −1.397, p = 0.052) remain negative and marginally significant, implying potential coordination or influence constraints at intermediate levels. However, the relationship becomes less consistent at higher thresholds. FEMALE ≥ 8 is positive but insignificant (β = 0.0582, p = 0.701), indicating no meaningful effect. Interestingly, FEMALE ≥ 9 shows a positive and statistically significant coefficient (β = 0.3825, p = 0.049), implying that beyond a certain threshold, the relationship may reverse. This pattern provides strong support for the critical mass theory (Kanter, 1977). It demonstrates that female directors begin to exert substantive influence only after their representation reaches a meaningful threshold.

The results are consistent with prior findings by Torchia et al. (2011), Post et al. (2011), and recent extensions by Dias et al. (2024) and Shakil et al. (2026), all of whom emphasize that gender diversity’s sustainability effects are contingent upon reaching a critical mass rather than mere presence.

This nonlinear pattern suggests that the relationship between board gender diversity and environmental performance may not be strictly monotonic. Beyond a certain threshold, the positive impact of women’s presence on sustainability outcomes may diminish or even reverse.

One plausible explanation lies in critical mass and social identity dynamics. According to Kanter’s (1977) critical mass theory, women begin to exert substantial influence on board deliberations once they surpass a certain threshold. While Torchia et al. (2011) established that a critical mass of at least three women is necessary to move beyond tokenism and contribute to innovation, subsequent research suggests that this relationship is non-linear. Beyond a certain point, numerical dominance by either gender may reintroduce homogeneity and groupthink, reducing the board’s ability to critically challenge environmental strategies. In other words, diversity benefits arise from balanced representation rather than numerical dominance. When one gender becomes overwhelmingly represented, groupthink may re-emerge, reducing the richness of debate and the board’s ability to critically challenge environmental strategies.

Another explanation relates to firm-specific characteristics. Boards with a high number of female directors are more likely to be observed in larger firms, which typically have larger boards and are subject to stronger diversity requirements. These firms also tend to generate higher levels of emissions and more extensive disclosure, which may contribute to the observed positive association (Nuber & Velte, 2021).

In addition, sectoral composition may play an important role. Firms with a high number of female directors may be concentrated in specific industries, such as service or consumer-oriented sectors, which are associated with complex supply chains and higher emissions levels (García Martín & Herrero, 2020).

Finally, this result may be influenced by sample limitations, as the number of firms with very high female representation (nine or more female directors) is relatively small. This may lead to less stable estimates and greater sensitivity to outliers. Therefore, this finding should be interpreted with caution. Consequently, the observed positive association between a very high number of women and emissions might reflect sectoral composition rather than a causal effect of gender composition per se.

Firm-specific controls behave as expected: profitability (ROA) and firm size (F-SIZE) are both positive and significant, indicating that more profitable and larger firms possess greater resources and incentives to engage in carbon reporting (Luo et al., 2022).

Like Zhao et al. (2020) who found that environmental degradation and carbon emissions are associated with higher financial leverage in Chinese provinces. Our results show that leverage (LEV) is also positive and significant at the 10% level, indicating that highly leveraged firms may face financial constraints that limit their ability to invest in emission-reduction technologies.

5. Robustness Test

To test the robustness of the findings to different measures of environmental performance, the dependent variable was replaced with carbon intensity measured as total GHG emissions scaled by firm revenue. The coefficients of board gender diversity retained their signs and significance, supporting the stability of the results (See

Table 6. Robustness test.

FEMALE	−0.0523816 *
	0.064
BIND	0.0029216
	0.773
DUALITY	−0.1469854 **
	0.016
ROA	0.5371442 ***
	0.047
F-SIZE	0.1471866 *
	0.000
LEV	0.3493405 *
	0.072
R2	0.2107
Number of obs.	148

Note: *, **, and *** represents statistical significance at the 10%, 5% and 1% level respectively. All variables are as defined in Table 1.

).

6. Conclusions

This study explores the influence of board gender diversity and the attainment of a critical mass of female directors on corporate carbon emissions. Consistent with agency and legitimacy theories, the findings suggest that diverse boards can strengthen environmental oversight and accountability. However, in line with critical mass theory, the results demonstrate that gender diversity contributes to lower carbon emissions only when female directors represent a meaningful proportion of the board. Below this threshold, the presence of women tends to be symbolic, exerting limited influence on sustainability outcomes.

These findings extend prior research on gender and governance by emphasizing the non-linear nature of diversity’s impact on environmental performance. The results reinforce the argument that token female representation is insufficient to shape board discussions and strategic direction. When a critical mass of women is achieved, their collective voice promotes stronger ethical awareness, stakeholder responsiveness, and environmental responsibility—core themes within effective governance frameworks.

From a policy perspective, this study underscores the importance of governance reforms and gender balance initiatives in enhancing corporate sustainability. The findings are particularly relevant in the context of European and French regulations such as the Copé–Zimmermann Law and the EU Corporate Sustainability Reporting Directive (CSRD), which encourage greater diversity and transparency in corporate governance structures.

While the study provides valuable insights, some limitations should be acknowledged. The sample is limited to French non-financial firms, which may restrict generalizability. Future research could extend this analysis to other institutional contexts, integrate dynamic panel models to address potential endogeneity, and explore how women directors influence specific board decisions related to carbon management and green innovation.

In conclusion, this research affirms that gender-balanced boards are essential for effective corporate environmental governance. By moving beyond symbolic representation toward substantive inclusion, firms can strengthen their commitment to sustainability, reduce emissions, and enhance long-term stakeholder trust.