Every projection of the UK’s forestry future assumes a warming climate: hotter temperatures on a fairly smooth ever-increasing line, with wetter winters and drier summers stacking up decade on decade. That’s the world our current species-selection matrices, provenance guidance and rotation plans are built for. It is also, on the evidence now emerging, only one of two plausible 2080s.
The other scenario is a UK that exists in globally-warmed environment but which has cooled locally: a genuine regime change driven not by how much carbon we emit, but by whether a critically important ocean current keeps circulating. If the Atlantic Meridional Overturning Circulation (AMOC) collapses, or even weakens sharply, temperatures over the UK could flip from rising to falling within a matter of decades, arriving faster than most of the trees we plant this year will reach maturity.
This thinkpiece is a follow-up to AMOC Collapse: an Overlooked Risk to UK Forestry. It sets out both possible futures in realistic terms, then tests them against three kinds of woodlands. My intention isn’t to project which future will arrive, but to ask whether the decisions being made on the ground today would survive either of these contrasting scenarios.
Defining the two possible 2080s
Scenario A: extreme warming, AMOC intact
This is the typical high-emissions pathway (UKCP18, RCP8.5) that is widely accepted, and it remains the scenario most forestry planning already assumes.
- Summers up to 5.4°C hotter and winters up to 4.2°C warmer than the 1981–2000 baseline
- Average summer rainfall down by as much as 47%, average winter precipitation up by as much as 35%
- Winter extreme rainfall events around 40% more intense than previously modelled
- Hot spells and droughts moving from occasional to routine; a summer as hot as 2018 becoming close to a coin flip by mid-century
In short: a warmer, wetter-in-winter, drier-in-summer for the UK, with the extremes of both seasons more prominent.
Scenario B: AMOC collapse in a warming world
Recent modelling that combines an AMOC collapse with ongoing global warming finds the cooling signal wins in Europe even in a world that is 2°C warmer overall.
- Substantial cooling over Europe specifically, with sharp drops in average winter temperature and more intense cold extremes, while the rest of the warming world continues to heat up around it
- Arctic sea ice extending as far south as Scandinavia and parts of the UK and Netherlands, amplifying the cooling further through reflected solar radiation
- London’s average winter temperature falling to around 1.9°C, with roughly 18 freezing days a year and one-in-ten-year cold extremes near minus 19°C; Edinburgh’s equivalent cold extremes reaching towards minus 30°C
- A stormier northwestern Europe, as the sharpened temperature gradient between a cold north and a still-warming south strengthens the jet stream
It’s important to be careful about the science here, rather than overstating the facts. The Met Office’s own 2025 study concluded the AMOC is unlikely to collapse this century, finding the circulation sustained by Southern Ocean wind-driven upwelling even under heavy freshwater forcing. Other groups, working from longer observational records and different assumptions, put the odds considerably higher, with one widely reported study giving 95% confidence of collapse somewhere between 2025 and 2095, most likely around 2057. The IPCC holds only medium confidence against an abrupt pre-2100 collapse. This is a live disagreement between climate modellers, and such a scenario should be read as a genuine ‘tail risk’ rather than a consensus forecast. That is precisely what makes it worth planning for.
Three woodlands under two futures
It is helpful to consider these two opposing climate futures scenarios in the context of three case studies of the most common woodland owner/type in the UK. It brings the potential consequences to the fore and hopefully will resonate more strongly with policy makers, professional foresters and landowners alike.
Commercial estate: Sitka spruce
Sitka’s limiting factor in the UK has never been cold tolerance. It’s moisture, and that single fact governs its exposure under both scenarios.
Under Scenario A (warming), the threat is direct: summer drought stress on sites already marginal for water availability, particularly on the shallower, free-draining soils that make up a meaningful share of the current commercial estate.
Under Scenario B (cooling), the threat is subtler but no less impactful. Colder winters won’t trouble Sitka spruce because being native to northern latitudes in North America, it is naturally well adapted. But stormier conditions together with disrupted precipitation, layered onto sites whose water balance was dependent on a mild oceanic climate, could shift soil moisture availability in ways that current planning and investment has largely not accounted for. A significant additional issue is wind. A stronger jet stream and more intense storms raise the effective wind hazard classification (DAMS score) on exposed ground, meaning trees reach ‘critical height’, the point past which windthrow probability rises sharply, at a younger age on more of the current estate than rotation plans assume. Under Scenario A (warming), drought stress does similar damage but under different terms: weakened rooting and reduced anchorage on shallow or restricted soils can make a tree windthrow-prone even without a change in storm intensity, simply because it’s less able to hold itself up.
For an investor, this changes what actually needs modelling. Wind hazard classification can’t be treated as fixed at planting; it needs revisiting through the rotation, since a site’s risk profile can shift materially within a single 40 to 50-year conifer cycle. That favours shorter rotations with earlier, lighter thinning over the traditional late heavy thin, itself a known windthrow trigger on stands grown tall and dense before their crowns are first opened by foresters. Harvest timing is better modelled as a probability distribution than a fixed date: an unplanned storm-driven salvage felling, priced low and synchronised with every other owner doing the same thing at once, is a realistic scenario a clean 45-year clearfell model doesn’t capture. Insurance and lending terms are likely to start pricing this in directly as regional wind and drought exposure become better quantified.
That points to a genuine trade-off. Even-aged Sitka monoculture remains the highest-yield, most mechanisable option in a stable climate; mixed-species or continuous cover systems cost more to manage and produce lower peak volume per hectare. But diversity ‘buys resilience’: it breaks up the uniform canopy blocks that funnel wind between compartments, smooths cash flow through periodic selective felling rather than one rotation-ending payout a single storm can wipe out, and spreads market exposure across more than one timber price cycle. Monoculture wins on expected yield in a stable climate; diversified structure increasingly wins on risk-adjusted return once a realistic probability of early, storm-forced harvest is priced in under either 2080.
The uncomfortable conclusion for commercial forestry is that both scenarios point to the same underlying variables. Water and wind, not temperature, are what the next rotation should be designed around, and that is a site-by-site question no national species guideline can fully answer at this point in time.
Ancient semi-natural woodland
Ancient semi-natural woodland (ASNW) has no capacity to migrate and, practically speaking, no capacity (including ‘permission’ under current leglstation) to be redesigned. Its irreplaceability is precisely what makes both scenarios dangerous, but coming from opposite directions.
Under Scenario A (warming), the threat is familiar from a decade of drought-year monitoring: moisture-sensitive species, beech prominent among them, showing crown dieback and elevated mortality, alongside pest and pathogen pressures shifting northward into ecosystems with no experience of them.
Under Scenario B (cooling), the threat is one this ecosystem has no adaptive memory of at all. Generations of oceanic mildness have shaped these woods around the near-total absence of hard frost and sustained winter cold. A shift towards London-in-winter conditions resembling minus 19°C cold extremes, arriving within decades of a tipping point being crossed, is not a stress this system has been selected for at any point in its history.
This is the case study where intervention is hardest to justify and inaction is hardest to defend, but ‘hardest to justify’ is not the same as ‘unavailable’. Selective thinning to ease competition for water, PAWS restoration releasing the ancient seed bank from non-native nurse crops, and deer management to support natural regeneration are already live ASNW techniques. None can migrate a woodland or rewrite its species list, but they can buffer drought stress under Scenario A and, with more deliberate structural planning, wind and frost exposure under Scenario B.
The harder question is whether structural management is enough on its own, and here the orthodoxy deserves to be challenged. The convention against moving provenance or introducing species into ASNW protects genetic integrity and irreplaceable character. This is a significant conservation principle, but we should now recognise that it has a cost. For instance, a beech-dominated ASNW that dies back wholesale under Scenario A drought has not had its irreplaceable character protected. Where the realistic choice in some ASNW is between a woodland altered by careful, monitored provenance enrichment and no woodland at all, a healthy, adapted ASNW may be the better outcome than a faithfully sourced one that doesn’t survive to be faithful to anything.
Farmer creating new woodland
This is the owner in these scenarios with genuine options, because the decision is being made from bare ground with the whole design open to thoughtful design and implementation.
Under Scenario A (warming), a poorly-chosen planting plan faces the same drought and heat stress threatening the commercial estate and the ASNW alike, with the added disadvantage of establishment-phase saplings being far more vulnerable to summer moisture deficit than mature trees.
Under Scenario B (cooling), a poorly-chosen plan faces frost damage and storm exposure in species selected without any cold tolerance in mind, and an establishment phase disrupted by intensified Atlantic storms before root systems are anchored. No single species portfolio optimises for both futures. The design has to spread risk across both, not try to predict which one will arrive.
Three principles are worth considering:
- Structural and species diversity over any single option, with no species exceeding roughly 20 to 30% of stocking; monoculture creates the exposure that both scenarios will punish hardest.
- Favour species with broad climatic amplitude over specialists: oak, both sessile and pedunculate, for its deep-rooting drought tolerance and genuine frost hardiness; Scots pine, which copes with both summer drought and hard winters on poorer, free-draining ground; downy birch and rowan as frost-hardy pioneers and nurse species; small-leaved lime and hornbeam for drought-tolerant mid-canopy diversity; alder confined to genuinely damp ground likely to hold moisture under either future. Beech and Norway spruce are best used sparingly or avoided, for reasons that mirror the ASNW and Sitka spruce cases respectively.
- Finally, and most concretely supportable by policy makers, provenance is the real risk-management tool, not just species choice. Sourcing seed and stock from a spread of provenances, some from further south for heat and drought-adapted genetics, some from more continental or northerly sources for frost and storm hardiness, helping convert an unknowable 2080 into a managed genetic portfolio rather than a speculative guess.
Silviculturally, this favours continuous cover or close-to-nature forestry over even-aged planting: wider initial spacing to reduce drought competition, a retained mixed-age, mixed-height structure that is far more windfirm than a uniform canopy, and natural regeneration favoured once the stand establishes, so the forest can self-select for whichever climate actually materialises.
At a glance
Threats
| Woodland/Owner Type | Scenario A: Warming | Scenario B: Cooling |
|---|---|---|
| Commercial Sitka estate | Drought stress and weakened anchorage on shallow, free-draining sites | Raised windthrow hazard; earlier critical-height risk |
| Ancient semi-natural woodland | Drought-driven dieback (beech especially); northward-shifting pests | Cold and frost exposure for which the ecosystem has no adaptive memory |
| Farmer’s new woodland | Establishment-phase drought and heat stress | Establishment-phase frost and storm damage |
Opportunities
| Woodland Owner/Type | Scenario A: Warming | Scenario B: Cooling |
|---|---|---|
| Commercial Sitka estate | Faster growth where sites aren’t moisture-limited, especially further north | Cold tolerance is a non-issue; reduced bark beetle risk and pathogen pressure |
| Ancient semi-natural woodland | A stronger case, and funding case, for trialling structural management and assisted provenance now | Some non-native pests and pathogens checked by colder winters |
| Farmer’s new woodland | Widest species and provenance palette of any owner, chosen from bare ground | First-mover position on climate-resilient stock, ahead of policy guidance |
Response
| Woodland Owner/Type | Response |
|---|---|
| Commercial Sitka estate | Site-by-site water and wind design; shorter rotations, earlier thinning, diversified structure |
| Ancient semi-natural woodland | Structural management now; trial assisted provenance where the alternative is losing the woodland and its ecosystem |
| Farmer’s new woodland | Diverse species mix, broad climatic amplitude, spread of provenance sourcing |
Summary: the decisions we can’t take back
What I’ve laid out in this thinkpiece isn’t only a new problem for forestry, it’s a more significant one by an order of magnitude. Foresters have always committed land for a century or more while markets and policy shifted around the forest in a fraction of that time. The emerging AMOC threat is the same challenge, now applied to the climate rather than societal evolution alone. It will come to bear on a profession already serving two masters that don’t always and readily agree: timber and amenity on one side, conservation on its own terms on the other. A forked climate doesn’t only increase tension but it doubles both the complexity and the challenge.
Attempting to look past which of these futures may arrive, and a fundamental pattern emerges. The owners with the least flexibility will face the most consequential decisions soonest. The owner with the most flexibility is most likely to gain as their forest resource is more likely to adapt, or in other words demonstrate resilience.
Ancient semi-natural woodland can’t migrate and can’t be redesigned. It will have to meet whichever future arrives largely as it stands. The convention against intervening has never been tested against the risk of losing the woodland altogether. It’s time to test this with some bold policy at national level and thoughtful management planning at the forest level.
Commercial Sitka is being replanted this decade, on rotations that will still be standing in 2080, against water and wind assumptions neither scenario actually delivers. This should no longer be considered a future risk, rather a current and live error in planning and foresight, and it is being made on real ground, right now.
The farmer creating new woodland is in the strongest position of the three, and the guidance hasn’t fully caught up yet. Bare ground and a blank species list are an advantage no other owner has, currently squandered by strategies and policies built for one climate when the science has forked into two fundamentally opposing scenarios.
It may not be unfair to suggest that the accepted practice of the forestry profession remains unwilling to accept how far, and how fast, the climate underpinning it has already moved, because admitting it disrupts everything that it has invested in. But we should accept risk aversion might well lead to destruction.
Three imperatives follow:
- The commercial investor must diversify: monoculture is no longer the safe position, it’s most exposed to risk.
- The ASNW owner must stop preserving in aspic: a woodland frozen in the image of the last two centuries risks becoming no woodland at all.
- The farmer starting from bare ground has the least to lose and the most to gain, and should embrace the extremes rather than plan around a single future.
Look past which future may arrive, and a pattern emerges. The owners with the least flexibility will face the most consequential decisions soonest. The owner with the most flexibility is most likely to gain as their forest resource is more likely to adapt, or in other words, demonstrate resilience.
Gabriel Hemery
References and further reading
- Hemery, G. (2026). AMOC Collapse: an Overlooked Risk to UK Forestry. gabrielhemery.com. https://gabrielhemery.com/blog/2026/09/16/amoc-collapse-an-overlooked-risk-to-uk-forestry/
- Hemery, G. (2026). Trees and Drought: Fifty Years After 1976, What Drought Means for Britain’s Trees. gabrielhemery.com. https://gabrielhemery.com/blog/2026/07/15/trees-and-drought/
- Hemery, G. (2026). After the Heatwave: Tree Species Adapted to Droughts. gabrielhemery.com. https://gabrielhemery.com/blog/2026/08/05/after-the-heatwave-tree-species-adapted-to-droughts/
- Forest Research. ‘Continuous Cover Silviculture.’ https://www.forestresearch.gov.uk/research/continuous-cover-silviculture/
- Heubel, S., Rammig, A. and Buras, A. (2025). ‘The Forest After Tomorrow: Projecting the Impact of a Collapsing Atlantic Meridional Overturning Circulation on European Tree-Species Distributions.’ Global Change Biology, 31(4), e70185. https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.70185
- Met Office (2025). ‘Climate Change: AMOC Likely to Withstand Future Warming’, reporting on Baker, J. et al., Nature. https://www.metoffice.gov.uk/about-us/news-and-media/media-centre/weather-and-climate-news/2025/climate-change-amoc-likely-to-withstand-future-warming
