Effects on habitats

Climate change is the single greatest threat to Scotland's habitats. Habitats are being altered in a number of different ways by climate change. The effects of climate change are threatening habitats from the mountain tops to the sea bed.

How does climate change affect habitats?

Some habitats will be affected directly, for example existing coastal machair habitats may be lost due to sea-level rise. More commonly, however, climate change will alter the intricate ecological balances that allow the plants and animals to grow and thrive. For example, climate change projections suggest that the arctic-alpine habitats of Scotland's mountain tops could be colonized by woodland and scrub habitats as the climate warms, but the extent to which this will happen will be dependent on availability of scrub and tree seeds on the open hills, and the likely increased grazing pressure from deer.  There is even a possibility that the projected windier and wetter summers could favour the current arctic-alpine habitats. Thus, whilst we are sure that many habitats will change, there is still considerable uncertainty exactly what change will look like.

Different habitats will be affected in different ways. On the coast, machair habitats are likely to flood as sea levels rise whereas sand dune habitat may start to move inland.  Changing rainfall patterns will result in rivers flooding more regularly. On land, rising temperatures are expected to mean that zones of arctic heath will need to move further north and/or to higher altitudes. This could obviously be very serious for those habitats that are already growing at the extremes, such as on mountain summits, they will ultimately have no where to go and will be lost.  Another consequence of rising temperatures combined with a reduction in rainfall, is that peatland soils and habitats will be damaged by drying out and eroding.

Will habitats be lost/damaged by climate change?

Yes, some habitats will probably be lost, although perhaps a more common outcome will be really significant changes within existing habitats. In some pinewoods, we may keep the pines, but see a change from heathery vegetation beneath the trees to grass and bracken, due to reduced frosts and nitrogen enrichment. That in turn would create other winners and losers amongst the wildlife of those pinewoods. Coastal habitats, may be lost in places where it is not possible for them to migrate inland due to coastal defences. At present 100 hectares of saltmarsh and mudflats are lost in the UK every year as a result of sea-level rise and erosion.

Can habitats respond to climate change?

While the rapid pace of climate change is one of its principal threats, the ability of habitats to respond quickly will be limited. Habitats that are supported by natural process are known to be better able to respond to climate change. For example, rivers that have natural patterns of erosion and have intact floodplains will be best able to cope with the increased flooding resulting from increased rainfall. Development of towns, roads, etc. on floodplains reduces the ability of rivers to respond and raises the risk of increased damage to homes and businesses.

Having enough space will be another factor. Other habitats already suffer from fragmentation (e.g. areas of woodland are often cut-off from one another). Isolated areas of habitat will be more vulnerable to irreversible damage from rapid climate change.

Can we predict these changes?

Not as well as we might wish. Recent research has found that freshwater habitats can be damaged by climate change in some unexpected ways. It appears that climate change will mimic and exacerbate the effects of acidification and nutrient enrichment  , compounding effects our society is already having. Other recent research has found that particular pathogens have become more damaging to woodland following recent increases in temperature and rainfall.

Such results show the need for continued further research in order that we can properly anticipate and manage climate change effects.