As autumn unfolds in the New Forest, resident Bill Reynolds shares his observations during a recent walk. “Things have altered a bit,” he remarks, noting the oak trees’ delayed transition into autumn colors. “I think the difference is about two weeks, and it seems to be getting later still.” For several years, Reynolds has been capturing the area’s beauty through photographs, sharing them with members of the Southampton to New Forest Facebook group, where others have also noted the trees’ prolonged green hues. “I’m just an observer, but I’ve seen that it’s not just a sudden change—it’s been happening for some time.”

To shed light on this natural phenomenon, Liz Bentley from the Royal Meteorological Society explains, “The shortening of days combined with lower light levels halts the production of chlorophyll—the green pigment in leaves. As this green fades, the reds, oranges, browns, and yellows that lie beneath start to emerge.” She notes that sufficient sunshine and rainfall are crucial for trees to build up sugars in their leaves; without adequate rain, trees experience stress, leading to premature yellowing, browning, and leaf drop.

Reflecting on last year’s weather, Bentley describes a “false autumn” in August brought on by an exceptionally hot and dry summer, which caused trees to drop their leaves early because of stress. In contrast, the mild and wet conditions experienced this year have allowed the chlorophyll to persist, keeping the leaves green.

According to statistics from the Met Office, average autumn temperatures in south-central and southeast England have risen from 5.8°C between 1961 and 1990 to 7°C from 2014 to 2023. The Woodland Trust’s Nature’s Calendar project is charting long-term seasonal trends, collecting data on key events such as the first snowdrop bloom, the return of swallows, and the ripening of autumn fruits. Dr. Kate Lewthwaite from the trust indicates that the current mild weather is extending the growing season. “Changes in seasonal event timing are often the first indicators scientists notice,” she says, emphasizing that while some species may thrive, many others may struggle in a changing climate.

The National Trust also notes that this year’s unpredictable weather may impact the vibrant displays of autumn colors at its properties. Pamela Smith, the Trust’s senior consultant for gardens and parklands, warns that changing weather patterns make traditional autumn displays increasingly uncertain. The prolonged green foliage on trees may also heighten the risk of damage from autumn storms.

Dr. Rob Salguero-Gómez, an Associate Professor of Ecology at the University of Oxford, highlights how climate change is profoundly impacting the life cycles of plants and insects. “If plants are shifting their seasonal timing four times faster than the insects that depend on them, this mismatch threatens the entire ecological system.” He points out that about 60% of the relationship between plants and insects across Europe is changing significantly. “Plants are waking up earlier, growing faster, and reproducing sooner, while insects struggle to keep pace. This creates a disconnect that could have serious consequences for the ecosystem.”

In the context of our ecosystem, humans sit at the top of the food chain, relying on both plants and animals for sustenance. Salguero-Gómez concludes, “Ultimately, our well-being depends on how successful plants are in adapting to these changes.” You can follow BBC Hampshire & Isle of Wight on social media platforms for continuous updates.