Macauley Institute (now the James Hutton Institute) did some modelling on the effect of climate change on Land Capability for Agriculture in Scotland using the UKCP09 scenarios. Their report is http://www.programme3.net/LCAREPORTweb.pdf Doesn't cover the whole of the UK though.

There will also be social considerations around demand for food, fuel crops etc which will also drive whether an uphill and northward movement of arable/improved grassland actually happens

Dear Janet, Thank you very much for your extremely helpful response. Can I tke it that your expectation is that climate change would, if anything, result is a reduction in rough grazing in Scotland. If so, then, presumably, you would expect this trend to be even more marked further south in england. I don't want to lead your esponse (which is quite important to what we are doing) so do feel free to disagree with this.

I ran this question past a colleague in Agriculture Canada who is actively considering the issue of 'marginal land'. He adds some practical perspectives, which I am inserting, below:

"The answer is…it depends.

It depends on the particular aspect of the soil that makes it marginal as well as what the change in climate actually results in. If, for example the soil is coarse textured and therefore droughty but the result of the change in climate is on average more frequent rains, there may be the opportunity to increase the stocking rate of livestock or if the marginality is marginal perhaps shift into a cropping situation perhaps even into a high value crop like vegetables. This will also depend of course on the access to market. On the other hand, if the change in climate is towards less and more infrequent rains, then the opposite is true and the stocking rate will likely be reduced or in the extreme, the land abandoned.

It also depends to a large extent on the type of agriculture practiced. If the land in question is a large (hundreds of square kilometers) block of marginal land that has been largely grazed then, even in the first example where the land is improved to a cropping standard, the change is likely to be towards a higher stocking rate rather than a cropping scenario at least in the short term. This, largely due to the investment in infrastructure necessary and the change in culture that would be required. It’s pretty hard to change a cowboy into a sodbuster. Given a generational change or as new infrastructure or machinery is necessary the change to cropping may come. If the land is in small blocks surrounded by cropland then the switch would be more rapid because the infrastructure and cropping culture already exists.

In the case where marginality is as a result of more severe restrictions such as shallow soils or extreme stony conditions the chances are that wetter would simply mean higher stocking rates and drier would result in less stocking or abandonment.

As usual we are throwing around the term marginal without a reasonable idea of what it means."

I think Ruth captured the whole essence. What makes the land marginal? Is it a slope? What is the degree of slope? What is the nature of the soil? The texture etc.? Is the climate change causing increase or decrease in precipitation? What is the pattern of rainfall distribution, the snow cover, and the dry spell. Any close source of water for irrigation? What are the available alternatives for rejuvenation of the marginal land under the circumstance? Appropriate response to these will help in determining the stocking capacity and the handling of the land and the stock.

Hi Ian,

I suggest you contact Davy McCracken

http://www.sruc.ac.uk/info/120256/sustainable_ecosystems

And/or Tony Waterhouse

http://www.sruc.ac.uk/info/120194/beef_and_sheep_research_centre

At SRUC.

Unlike many parts of the world in the UK marginal land is general cold, wet and peaty, so the restriction isn't due to low rainfall (if anything the opposite is true), or shallow soils (some peats are several metres deep, although montaine soils right at the top of hills can be quite shallow). Projections for climate change in the UK are fairly well characterised by the UKCP09 projections. The Macauley modelling does indeed show a likely decrease in marginal land in Scotland as managed grassland becomes fit for arable use and rough grazing becomes more amenable to management. Given the high percentage of unimproved/marginal land in Scotland there are unlikely to be many competing pressures so it is quite likely that there will be significant land use change, especially as climate change elsewhere and climate-driven migration is likely to increase demand in the longer term. However policy around this may need to be developed to restrict this e.g to prevent drainage of peatland for agriculture with consequence loss of ecosystem services such as carbon storage, flood mitigation etc. Hard to predict how this would play out against economic drivers.

On a scientific basis the same pattern of change in potential land use is likely to be true for England although I've not seen any models on this. However, there is a smaller percentage of marginal/rough grazing land (depending on how you are defining this e.g Countryside Survey has a fairly limited definition of rough grazing whereas the IPCC definition of unimproved grassland covers a much wider range of habitats). A lot of this has secondary uses e.g as grouse moor or as "access land" under the Countryside and Rights of Way Act which is open for recreation. In these areas there may be other pressures which restrict the change e.g shooting estate owners continuing to manage uplands for primarily for grouse and National Parks resisting moves to enclose rough grazing.

I suspect that in Wales the social side of things would be more like Scotland with less resistence to land use change, again with similar projected patterns of change, although as with England I am not aware of any projections for climate driven land use change. In Northern Ireland the vast majority of grazing is already improved - there is very little land which could be classified as rough grazing or marginal, so there would be less change expected here because the baseline is different.

Please also see our recent correspondence "climate change matters because the oak can not move upward" and make some comments on it.