WASHINGTON, D.C. — A new University of California study finds that California’s coastal redwoods, the world’s tallest trees, are experiencing a measurable slowdown in photosynthesis as summer temperatures climb above 30 °C, raising concerns for carbon markets and forest‑conservation policy.

The research, led by Dr. Emily Chen of UC Berkeley’s Department of Ecology, tracked 12 mature redwoods in the Redwood National and State Parks over a five‑year period. When ambient temperature rose to 31 °C, the trees’ carbon‑fixation rate fell by roughly 30 %, a change the team says is comparable to a short‑term heatstroke in humans.

Redwoods store an estimated 2.5 billion metric tons of CO₂, a figure that underpins more than $2.5 billion in carbon‑credit contracts sold to corporations seeking to meet ESG goals. “If photosynthetic efficiency drops, the projected sequestration numbers in the voluntary market could be overstated by up to 15 %,” said Maya Patel, senior ESG analyst at GreenBridge Capital.

California’s climate‑action plan, which aims to protect one million acres of old‑growth forest by 2030, may need to incorporate temperature‑risk buffers. State officials are reviewing the study’s findings as part of a broader effort to align forest‑management subsidies with the latest climate‑science data.

Investors are watching closely. The redwood sector has attracted $450 million in recent venture funding for precision‑monitoring technology, and a shift in tree health could affect the valuation of related REITs and timber‑linked ETFs. “Policy uncertainty combined with physiological stress signals could prompt a re‑rating of redwood‑based assets,” Patel added.

Key Takeaways

• Redwood photosynthesis drops about 30 % when temperatures exceed 30 °C.
• Reduced carbon uptake could shave $300 million–$400 million off projected carbon‑credit revenues.
• Policymakers and investors are urged to factor climate‑induced physiological stress into forest‑conservation strategies.

As the planet warms, the iconic giants of the Pacific coast may no longer serve as a reliable climate buffer without targeted adaptation measures, underscoring the need for integrated policy, scientific monitoring, and prudent investment practices.