Introduction

Changes in the climate of the UK accelerated in the 20 th century as increasing amounts of greenhouse gases were released into the atmosphere. Scientific consensus is now almost unanimous in stating that climate change is accelerating due to human activity.

Much of the information in this plan is taken from Conserving biodiversity in a changing climate (Hopkins et al 2007). The plan serves as a summary of this guidance for local readers and develops local objectives and actions to meet the challenges of climate change to the conservation of biodiversity.

Climate change scenarios

Climate change scenarios have been developed for the UK by the UK Climate Impact programme (Hulme et al 2002). Predictions differ between low and high emission scenarios and between the northwest and southeast of the UK , however all the scenarios agree on the following:

•  Average minimum temperatures will increase in both summer and winter.

•  Average maximum temperatures will increase in both summer and winter.

•  Precipitation will rise in winter and fall in summer.

•  Snowfall will decrease significantly in winter.

•  Absolute humidity will rise in summer and winter.

Extreme weather events are also a prediction of the climate change models. Predictions of future climate scenarios are inherently uncertain, but climate change is already taking place.

Response of biodiversity to climate change

Key impacts of climate change on wildlife include:

•  Changes in timing of seasonal events (phenology), leading to loss of synchrony between species and the availability of food and other resources.

•  Changes in species abundance and range through changes in suitable climatic conditions.

•  Changes in habitat preferences as microclimates in preferred habitats alter.

•  Widescale losses from extreme weather events

•  Increased survival or spread / new arrival of pests and diseases.

•  Indirect effects on wildlife from changes in land use induced by climate change, such as different or reduced livestock distribution, new crops for biofuels and so on.

Modelling the effects of climate change on different species in the UK shows that there will be winners and losers. Many northern or upland such species may contract in range or even disappear as the suitable climate space contracts, whereas many southern species may move into newly suitable habitat further north.

The ability of many species to disperse and expand into this new climate space will, however, be limited by a number factors including the species' dispersal ability and the proximity of suitable habitat. Fragmentation of habitat is an important obstacle to be overcome on a national, regional and local level to help species adapt to climate change.

The ability of less mobile species to adapt to a changing climate will depend to some extent on the availability of varied and suitable microclimates within habitat patches.

Helping biodiversity adapt to climate change

The uncertainty surrounding climate change scenarios themselves, and the even greater uncertainty surrounding the reaction of different species and ecosystems to change means that the best we can do is to plan for an uncertain future.

In practice this means:

•  Protecting what biodiversity we have, i.e. all protected sites and other semi-natural habitats.

•  Reducing pressures on biodiversity from sources not linked to climate change, i.e. abandonment of traditional management, over-grazing, nutrient enrichment, invasion by non-natives etc.

•  Developing ecologically resilient and varied landscapes and sites

•  Developing and protecting ecological networks of high quality habitats.

The first two of these principles are effectively covered in the Durham BAP through the individual action plans.

The need to develop our working practices and our capacity to follow the second two principles is clear.

Resilient and varied landscapes

Resilience is the ability of a landscape to maintain its functions after being disturbed or damaged. The maintenance of species diversity within a landscape is essential for it to be considered resilient and it is therefore vital that species are able to disperse to a more suitable location should their existing localities become unsuitable under a changing climate.

This needs to work on a variety of scales and so opportunities to conserve and create diversity within sites, between sites and within broader ecological networks should be found and taken.

The following characteristics are worth maintaining and enhancing:

•  Diverse and structurally varied vegetation

Different vegetation types have different micro-climates and some species can adjust simply by moving from one vegetation type to another (this is true of the silver-spotted skipper butterfly for example).

•  Semi-natural habitat on a range of slope and aspect

Microclimate varies considerably with topography, and could provide areas for some species to move if the change is not too extreme.

•  Uninterrupted semi-natural vegetation over a range of altitude

Allowing some species to move to higher areas.

•  Uninterrupted semi-natural habitat across coastal zones

Coastal areas have complex microclimates compared to inland areas and there is large climate variation over distances of less than a kilometre

•  Diverse water regimes

Rainfall patterns will change and rainfall may become less evenly distributed. The most complex range of habitats will survive in landscapes where there is variation from open water to dry land, which persists during weather extremes. This variation ismost likely to be sustained where wetlands are fed by a combination of surface drainage, ground water and aquifers.

On a small scale, new civil engineering projects such as embankments and quarry restorations should be encouraged to create new landforms with slopes of different aspects and gradients and a variety of hydrological regimes. Brownfield sites should be treated similarly to retain or create a variety of topographic features. Retention of small areas of scrub or unmanaged vegetation should be considered on or adjacent to grassland sites.

On a larger scale, the creation of transitional habitats such as scrub, rough grassland or newly exposed bare ground should be explored to enhance existing habitat networks.

Ecological networks

Ecological or habitat networks are the names given to a series of high quality habitat patches which are more or less connected by the intervening land.

Currently Natural England has developed software which will map idealised networks based on existing habitat inventory data, and the modelled permeability of the adjacent landscape to the dispersal of various species. As better data becomes available these network maps will become more accurate and more useful to, for example, planners and agri-environment schemes.

By protecting and developing habitat networks we are first protecting and buffering key sites, and then enhancing those sites for biodiversity through better connectivity with similar habitats. The long-term effect is a more functional ecosystem which is better able to adapt to change and respond to disturbance, including the impacts of climate change.

The mechanisms for developing habitat networks can include agri-environment funding, simple negotiation with the landowner, site acquisition, or taking opportunities for habitat creation, for example, in mitigation measures linked to development.

As a principle, all resources should be spent first securing the extent and quality of the existing core networks, and secondly expanding, buffering and linking network patches. Habitat network maps are a useful tool for prioritising the limited resources of government agencies, local authority planners and conservation bodies.

Objectives Development of robust definitions of habitats to define core elements of habitat networks. Publication of accurate habitat network maps to enable planners and agri-environment agents to target resources - taking account of the need for climatic variation within networks. Adoption of habitat networks by planning authorities and others to prioritise conservation effort. Development of robust monitoring methodology to monitor health of habitat patches and networks. Expansion of habitat networks through creation of buffer zones around key sites. Successful negotiation with land-managers adjacent to important sites to reduce harmful practices. Adoption of practices by all land managers which build varied structure, variability of habitats and microclimates into all projects which create or restore semi-natural habitat. Opportunities sought and taken by land managers and planners to modify drainage regimes to increase the range of wet and dry conditions.