Rethinking Conservation in an Era of Climate Change
Conservation used to mean keeping species where they naturally occurred and protecting those places from human disturbance. Under rapid climate change, that strategy is no longer always enough. As temperatures rise, rainfall patterns shift and extreme weather intensifies, many plants and animals can no longer survive in their historical ranges. Habitats suitable for their survival are moving uphill, poleward or into entirely new regions.
This shifting ecological map has led scientists and conservationists to explore a controversial idea: assisted migration, also known as assisted colonisation or managed relocation. Rather than simply safeguarding existing protected areas, assisted migration involves deliberately moving species to regions where climate models suggest they will be able to persist in the future. The aim is to design climate-resilient ecosystems that can continue to support biodiversity as the planet warms.
The concept raises practical, ethical and ecological questions. Yet in a warming world, where extinction risks are accelerating, it is attracting increasing attention as a potential tool in the broader climate adaptation toolbox.
What Is Assisted Migration?
Assisted migration is a conservation strategy in which humans actively relocate species—plants, animals or even entire communities—outside their current natural range to areas projected to remain suitable under future climate scenarios. It differs from traditional translocations, which generally move species within their historical distributions, for example from one part of a river basin to another.
In the context of climate change, assisted migration is often framed as a last-resort measure for species that are:
- unable to disperse quickly enough to keep up with shifting climate zones
- trapped by human-made barriers such as cities, intensive agriculture or dams
- restricted to isolated mountaintops, islands or fragmented habitats
- already experiencing severe population declines linked to climate impacts
The idea is to anticipate where suitable habitat will exist in coming decades and move vulnerable populations there before local conditions become unlivable. In doing so, conservationists hope to prevent extinctions and preserve ecological functions that would otherwise be lost.
Climate Change and the Limits of Natural Adaptation
Species have always responded to environmental change by adapting in place, shifting their ranges or, if they cannot cope, going extinct. What makes the current climate crisis different is the speed and scale of change combined with extensive landscape fragmentation.
Average global temperatures have already increased by more than 1°C above pre-industrial levels, and many ecosystems are experiencing temperatures and moisture conditions with no historical precedent in human times. For many species, especially long-lived trees, alpine plants and small, isolated animal populations, the rate of climatic change now outpaces their capacity to migrate or evolve.
Natural dispersal is further limited by human land use. Continuous forests have been broken into patches. Grasslands are crisscrossed by roads and fencing. Rivers are obstructed by dams. Under such conditions, species that might once have climbed higher slopes or followed cooler microclimates northward simply cannot move fast enough to track suitable habitat.
These constraints are particularly severe for:
- High-elevation and polar species, which face a literal “escalator to extinction” as suitable conditions retreat beyond the physical limits of mountains or landmasses.
- Endemic species restricted to narrow climatic niches, such as island flora and fauna, that have nowhere comparable to go on their own.
- Fragmented populations that are genetically isolated and already stressed by habitat loss, pollution or overexploitation.
Against this backdrop, some ecologists argue that actively helping species move may be one of the few realistic ways to protect certain components of biodiversity.
Designing Climate-Resilient Ecosystems
The concept of climate-resilient ecosystems extends beyond single-species protection. It involves managing landscapes, watersheds and seascapes so that they can absorb disturbances, reorganise and continue to function in the face of climate stress. Assisted migration, when carefully planned, can contribute to this goal by maintaining key species and interactions that underpin ecosystem health.
Instead of trying to freeze ecosystems in their current states, conservationists are beginning to envision “future-ready” landscapes characterised by:
- Functional diversity: a wide range of species that perform similar ecological roles, providing redundancy if some are lost.
- Connectivity: habitat corridors and stepping stones that allow species to move and gene flow to occur across the landscape.
- Adaptive management: flexible strategies that can be adjusted as climate projections and ecological responses are updated.
- Refugia: microhabitats that remain relatively buffered from climate extremes and can serve as safe havens for sensitive species.
Assisted migration can fit into this broader design by introducing species that are likely to sustain these functions as climates shift. For example, bringing drought-tolerant tree species into a forest could help maintain canopy cover, soil stability and carbon storage even as local conditions become drier.
Real-World Examples of Assisted Migration
While still relatively rare and often experimental, assisted migration projects are already underway in various parts of the world.
In North America, some forestry and conservation initiatives are testing the relocation of tree species and seed sources to cooler or wetter regions. For instance, provenance trials have moved climate-adapted populations of commercial species like Douglas fir and lodgepole pine northward or upslope to identify where they might thrive in future climates. Similar work is being done with ecologically important non-commercial species used in ecosystem restoration.
In Europe, projects aimed at conserving threatened plants have considered moving alpine species to higher elevations or more northern ranges. On some islands, conservationists have relocated rare plants or invertebrates to nearby islands projected to remain less vulnerable to sea-level rise or extreme heat.
In Australia and New Zealand, where biodiversity is highly endemic and vulnerable, assisted colonisation has been discussed for species such as threatened reptiles, birds and plants whose current habitats are projected to become unsuitable.
These projects are typically small in scale and subject to rigorous monitoring, reflecting both the promise and the caution surrounding assisted migration as a climate adaptation tool.
Ecological Risks and Ethical Dilemmas
Despite its potential benefits, assisted migration is far from a straightforward solution. It carries ecological risks and ethical questions that must be weighed carefully.
One major concern is the possibility of creating new invasive species. A plant or animal moved to a new region might outcompete local species, alter food webs or spread diseases. Predicting how a relocated species will behave in a complex ecosystem is challenging, even with advanced modelling tools.
There are also questions about how to balance the needs of one species against the integrity of entire communities. Saving a charismatic or well-studied species through relocation might inadvertently harm lesser-known organisms in the recipient ecosystem.
Ethically, assisted migration raises issues such as:
- Who decides which species deserve to be moved and where they should go?
- How much ecological risk is acceptable in attempting to prevent extinction?
- To what extent should humans engineer future ecosystems versus allowing natural processes to unfold, even if they lead to losses?
There is also the danger that high-profile relocation projects could divert attention from more fundamental actions, such as reducing greenhouse gas emissions, restoring habitat connectivity and protecting remaining intact ecosystems. Most conservation scientists emphasise that assisted migration, if used at all, should complement—not replace—efforts to tackle the root causes of climate change and biodiversity loss.
Building a Framework for Responsible Assisted Migration
To minimise risks and improve outcomes, researchers are working to develop guidelines for when and how assisted migration should be considered within broader climate adaptation and conservation planning. Emerging frameworks typically emphasise several key steps.
1. Careful species selection
Not every species is a good candidate for relocation. Conservationists focus on those that are highly threatened by climate change, have limited natural dispersal capacity and play important ecological roles. Species with a track record of invasiveness are generally excluded.
2. Rigorous habitat suitability assessment
Climate models, species distribution models and local ecological knowledge are used together to identify potential recipient sites. These analyses consider not only temperature and precipitation, but also soils, existing communities, land use and the availability of mutualists such as pollinators or symbiotic fungi.
3. Risk analysis and stakeholder engagement
Potential ecological risks to both donor and recipient ecosystems are examined. Local communities, land managers, Indigenous peoples and policy-makers are engaged early in the process to discuss concerns, cultural values and management responsibilities.
4. Small-scale trials and adaptive management
Rather than immediately moving large populations, many projects begin with experimental plantings or small releases under close monitoring. Data on survival, reproduction, dispersal and ecosystem impacts guide subsequent decisions. If negative effects appear, interventions can be adjusted or halted.
5. Transparent governance
Because assisted migration crosses ecological and jurisdictional boundaries, it calls for clear governance structures and regulatory frameworks. International, national and regional guidelines can help ensure that decisions are based on scientific evidence and broadly shared societal goals.
Integrating Assisted Migration into Broader Conservation Strategies
When discussed in isolation, assisted migration can appear either as a silver bullet or as a dangerous interference. In practice, it is most likely to be effective when embedded in integrated strategies aimed at building climate-resilient landscapes.
Such strategies combine multiple approaches:
- Habitat protection and restoration to safeguard remaining natural areas and rebuild degraded ecosystems.
- Connectivity conservation through wildlife corridors, river restoration and green infrastructure that enable natural species movements.
- Genetic conservation to maintain diverse gene pools, increasing adaptive potential within species.
- Ex situ conservation in seed banks, botanical gardens and zoos as a backup for highly threatened species.
- Community-based management that incorporates local knowledge and ensures benefits for people who live with and depend on these ecosystems.
Assisted migration can act as a targeted measure within this mosaic, reserved for cases where other options are insufficient and where carefully conducted assessments suggest a high likelihood of net ecological benefit.
A Future of Designed, Not Static, Ecosystems
As the climate crisis deepens, ecosystems will change, whether humans intervene or not. Species will shift ranges, some will vanish locally or entirely, and new combinations of plants, animals and microbes will form so-called “novel ecosystems.” The question facing conservationists is not whether landscapes will be altered, but how intentionally and with what objectives.
Assisted migration forces society to confront this uncomfortable reality. It asks whether we are willing to accept a more active role in designing the ecological communities of the future in order to safeguard biodiversity, ecosystem services and cultural values. It also asks how much uncertainty and risk we are prepared to bear in attempting to avert irreversible losses.
In many cases, protecting nature in a warming world will still mean traditional measures: cutting emissions, halting deforestation, restoring wetlands and allowing species to move through connected landscapes. Yet for some particularly vulnerable species and ecosystems, assisted migration may provide one of the few remaining pathways to survival.
Thoughtfully implemented, grounded in science and ethics, and embedded in broader climate adaptation strategies, assisted migration could help build the climate-resilient ecosystems that will sustain both biodiversity and human societies in the decades ahead.
