Climate-related news has been shown to be financially relevant, and theory predicts that unexpected increases in climate concerns widen the green-brown return spread. Yet entered on its own in a standard factor model, climate attention does not significantly explain weekly green-minus-brown returns. We show that this null is partly an artifact of averaging across ambiguity states. Using weekly S&P 500 returns over 2011–2021 sorted by Refinitiv ESG scores, the marginal pricing effect of a climate-attention shock varies significantly with the level of clean-energy transition ambiguity. We proxy for this ambiguity with ClimateVoV, a novel option-implied vol-of-vol of clean-energy options that captures second-order uncertainty specific to the transition, distinct by construction from general market-wide uncertainty (VIX, VVIX). The marginal effect grows from near-zero at low ambiguity to approximately 8 basis points per week at the 75th percentile. The statistically significant relation is carried by unexpected decreases in climate concerns, not increases. This pattern is consistent with the partial release of worst-case transition discounts on brown firms when concerns ease under elevated ambiguity, compressing the green-minus-brown spread. Restricting the analysis to environmental-impact news yields the strongest interaction. The effect appears in disclosure-based (Refinitiv) but not risk-based (Sustainalytics) ESG sorts. The result survives rate, oil, and policy-uncertainty controls, while a placebo constructed from growth-tech options produces no significant interaction.