1. Introduction
As global warming intensifies and extreme weather events become more frequent, risks driven by climate volatility are increasingly affecting economic and social development. In response, governments around the world have introduced a series of targeted climate policies, such as strengthening environmental regulation [
1], providing green finance [
2], and improving carbon market development [
3]. However, amid evolving climate conditions and changing emissions-reduction pressures, climate policy instruments are frequently adjusted, leading to rising climate policy uncertainty [
4]. This, in turn, increases the complexity of firms’ financing decisions. Specialized, Refinement, Differential, and Innovation (SRDI) enterprises’ core businesses are often concentrated in climate-policy-sensitive areas such as green and low-carbon industries and advanced manufacturing, and they are highly dependent on external financing [
5]. Therefore, they are more significantly exposed to shocks from climate policy uncertainty. Against this backdrop, by examining how climate policy uncertainty affects SRDI enterprises’ equity financing decisions, this paper provides important insights for innovative SMEs to optimize financing decisions, enhance risk resilience, and promote sustainable development.
Climate policy uncertainty (CPU) refers to unclear or frequently changing climate and environmental policies issued by governments and other relevant institutions [
6,
7]. Existing research suggests that the impacts of CPU on firms are mainly reflected in investment, innovation, and green performance. In terms of corporate investment, rising climate policy uncertainty increases the volatility of investment returns, which leads firms to reduce investment, especially energy-related investment [
8,
9]. In terms of corporate innovation, climate policy uncertainty can stimulate firms to engage in green innovation [
10,
11]. However, policy uncertainty such as changes in government green subsidies can also hinder green innovation [
12]. In terms of firms’ green performance, an increase in climate policy uncertainty can raise corporate carbon emissions, undermine firms’ ESG performance, and exacerbate ESG greenwashing [
13,
14].
As innovative firms characterized by specialization, refinement, distinctiveness, and innovation, SRDI enterprises are a key force in driving industrial upgrading and enhancing economic development. Most of these firms focus on niche markets and build competitive advantages through innovation capabilities [
15]. Common features of such firms include high R&D investment, long cash conversion cycles, and relatively weak risk-bearing capacity [
16]. Compared with large firms, SRDI enterprises rely more on external capital to sustain ongoing R&D and capacity upgrading, and are therefore more vulnerable to policy changes [
17].
SRDI firms operating in areas such as energy-saving and environmental protection equipment, new-energy materials, and green intelligent manufacturing are often important carriers of low-carbon transition and green technological innovation [
18]. Their operating costs, technology-path choices, and financing conditions are therefore closely tied to the climate policy environment [
19]. When climate policy uncertainty rises, SRDI enterprises face a more complex financing environment: On the one hand, higher uncertainty may raise the risk premium for debt financing and tighten external financing constraints, making debt financing more difficult and thereby prompting firms to increase the share of equity financing [
20]. More importantly, this response may also reflect firms’ active efforts to hedge policy uncertainty in anticipation of future mandatory policy changes and stricter regulatory implementation. On the other hand, when uncertainty escalates further, climate policy uncertainty can increase the risk premium demanded by financial institutions, leading to lower firm valuations [
21]. A decline in firm value weakens the pricing basis for equity issuance, thereby increasing the cost of equity financing and exerting a restraining effect on equity financing. Therefore, as climate policy uncertainty increases, SRDI enterprises may need to balance between two financing strategies: “Preemptive Move” and “Wait-and-See.”
At present, research examining how climate policy uncertainty affects firms remains relatively limited, which is mainly reflected in three aspects: first, the discussion of climate policy uncertainty’s impact on firms’ financing structure is still insufficient; second, there is a lack of attention to the effects and mechanisms of climate policy uncertainty on SRDI enterprises as a distinctive group of firms; third, there is a lack of systematic testing of the internal mechanisms through which climate policy uncertainty affects equity financing, as well as its heterogeneous effects across firms with different characteristics. Therefore, uncovering how climate policy uncertainty reshapes SRDI firms’ equity-financing choices through multiple channels is not only of major theoretical value, but also of practical significance for improving the efficiency of green finance policies and promoting the sustainable development of SRDI enterprises.
Based on this, this paper conducts an empirical analysis using data on 262 SRDI enterprises from 2011 to 2023 and systematically examines how climate policy uncertainty affects the equity-financing decisions of SRDI enterprises, as reflected in the proportion of equity capital in firms’ total assets. The results show that climate policy uncertainty has a significant inverted U-shaped relationship with the share of equity capital among SRDI enterprises. When uncertainty is at a low to moderate level, firms tend to increase equity financing; however, when uncertainty rises further, firms reduce equity financing. This conclusion remains valid after robustness checks. Mechanism tests indicate that climate policy uncertainty affects equity financing mainly through higher debt-financing costs and lower firm value: the former induces equity financing to substitute for debt financing, while the latter suppresses equity financing by raising its implicit cost and tightening pricing constraints. Further heterogeneity analysis shows that this effect is more pronounced among privately owned firms, firms in more highly concentrated industries, and firms with weaker risk resilience.
The contributions of this paper are mainly reflected in the following three aspects.
First, in terms of research perspective, this paper extends the boundaries of research on the economic consequences of climate policy uncertainty. The existing literature mostly focuses on the effects of climate policy uncertainty on firms’ green investment or environmental performance and rarely examines in depth its role in reshaping firms’ capital-structure decisions [
22,
23]. By incorporating climate policy uncertainty into a framework of corporate financing choices, this paper empirically reveals a nonlinear inverted U-shaped effect of uncertainty on equity financing. This not only enriches theoretical research in the field of climate finance, but also offers a new perspective for understanding corporate financial behavior under uncertainty.
Second, in terms of the research object, this paper depicts the financing-decision responses of SRDI enterprises to climate policy uncertainty. Existing studies on policy uncertainty mostly focus on large, listed firms with abundant resources, often overlooking small and medium-sized innovative enterprises [
24]. Given that SRDI enterprises are characterized by high R&D intensity and strong reliance on external financing, this paper’s in-depth analysis of this specific group can help the government formulate relevant climate policies more precisely.
Third, regarding the mechanism, this paper clarifies the transmission channels through which climate policy uncertainty affects equity-financing decisions. This paper finds that climate policy uncertainty influences SRDI firms’ equity financing through a debt financing cost channel and a firm-value channel, and that its effects are heterogeneous across firms with different ownership types, industry concentration, and risk resilience. The conclusions provide useful references for optimizing corporate financing and enhancing firms’ sustainable development.
The structure of this paper is as follows.
Section 2 presents theoretical analysis and research hypotheses.
Section 3 describes the research design.
Section 4 reports empirical results and robustness tests.
Section 5 conducts mechanism and heterogeneity analysis.
Section 6 provides a discussion of the main findings.
Section 7 draws conclusions and puts forward policy implications.
6. Discussion
This study contributes to the growing literature on climate policy uncertainty by showing that its effect on SRDI firms’ financing decisions is not monotonic, but follows an inverted U-shaped pattern. This finding suggests that climate policy uncertainty does not simply suppress firms’ financing activities. At relatively low to moderate levels, rising uncertainty may induce firms to increase equity financing in a preemptive manner, mainly because higher debt-financing costs encourage substitution from debt to equity. However, when uncertainty becomes sufficiently high, valuation discounts intensify and the implicit cost of equity issuance rises, which discourages firms from further equity financing. Therefore, the financing response of SRDI firms reflects a shift from “preemptive move” to “wait-and-see.”
This result extends the existing literature in two respects. First, while prior studies mainly focus on the effects of climate policy uncertainty on investment, innovation, ESG performance, or firm value, this study highlights its role in reshaping firms’ financing structure. Second, by identifying the debt-cost channel and the firm-value channel as two countervailing mechanisms, this study provides a more nuanced explanation of why the overall effect of climate policy uncertainty on equity financing is nonlinear. This is particularly important for SRDI firms, which are highly dependent on external financing and more vulnerable to policy-induced financing frictions.
More broadly, our findings imply that the economic consequences of climate policy uncertainty depend not only on its level, but also on how financial markets transmit uncertainty into firms’ financing costs and valuation conditions. For innovative SMEs, excessive policy uncertainty may weaken financing capacity and ultimately hinder green transition and long-term innovation. Thus, the policy challenge is not merely to promote more climate policy, but to improve its predictability, credibility, and implementation consistency so that firms can make financing decisions under a more stable institutional environment.
7. Conclusions and Implications
7.1. Conclusions
Using a panel of 262 SRDI enterprises over 2011–2023, we find a robust, statistically significant inverted U-shaped relationship between climate policy uncertainty and the share of equity financing. Equity financing increases when climate policy uncertainty is low to moderate, but decreases once uncertainty becomes sufficiently high. Mechanism evidence suggests two offsetting channels: rising climate policy uncertainty increases debt-financing costs, prompting firms to substitute equity for debt, while it also depresses firm value, which raises the implicit cost of equity issuance and tightens pricing constraints, thereby discouraging equity financing. The inverted U-shaped pattern is stronger for privately owned firms, firms in more highly concentrated industries, and firms with weaker risk resilience. Overall, our findings indicate that climate policy uncertainty does not simply suppress or promote SRDI firms’ equity financing in a linear manner; rather, it exhibits a clear inverted U-shaped pattern, under which firms dynamically switch between “preemptive action” and a “wait-and-see” stance as climate policy uncertainty changes.
7.2. Implications
The findings of this study carry important implications for policymakers, firms, and financial institutions. Since climate policy uncertainty affects equity financing mainly through two opposing channels, namely higher debt financing costs and lower firm value, effective responses should focus not only on reducing policy uncertainty itself, but also on alleviating the financing frictions and valuation pressures generated by such uncertainty. In this sense, improving policy predictability and strengthening the equity financing environment are equally important for supporting the sustainable development of SRDI enterprises.
For policymakers, the key task is to reduce unnecessary climate policy uncertainty by improving the stability, transparency, and consistency of climate related policy design and implementation. In particular, governments should provide clearer policy roadmaps, transition timetables, and implementation standards for climate related regulations, so that firms can form more stable expectations regarding future compliance costs, financing needs, and investment returns. In addition, greater consistency between central policy objectives and local enforcement practices would help reduce uncertainty arising from heterogeneous regional implementation. Because our results show that excessive uncertainty eventually suppresses equity financing by lowering firm value, policymakers should also improve supporting institutions for equity financing, such as green equity investment programs, listing support for innovative SMEs, and more standardized disclosure rules for climate related risks and opportunities.
For firms, the results imply that financing strategies should be adjusted dynamically according to the level of climate policy uncertainty. When uncertainty is at a low to moderate level, firms may benefit from preemptive equity financing arrangements that secure capital before financing frictions intensify. However, when uncertainty becomes excessively high, firms should place greater emphasis on stabilizing firm value, improving climate related information disclosure, and strengthening communication with investors, so as to mitigate valuation discounts and avoid issuing equity under unfavorable pricing conditions. More broadly, SRDI firms should strengthen climate risk management, maintain financing flexibility, and enhance organizational resilience in order to better cope with policy induced financing shocks.
For financial institutions, the findings suggest the need to avoid mechanically amplifying policy uncertainty into excessively high risk premia or severe valuation discounts. Banks, equity investors, and other financial intermediaries should improve climate risk assessment frameworks for SRDI firms and distinguish between temporary policy uncertainty and firms’ long term growth potential. In particular, more diversified equity financing instruments, stronger green equity investment support, and greater participation of long term capital would help innovative firms obtain funding without suffering excessive undervaluation during periods of policy uncertainty. Such efforts would help ease both the debt cost channel and the firm value channel identified in this study.