nm1359: 
this week i'm i'm going to just basically one lecture which comes on from from 
last week's session er last week we looked at climatic change sort of 
observation measurements today i want to sort of link in with that the 
implications for crops vegetation and land use and it will hopefully tie 
together some of the bits of the course that we've been doing with this this 
term er so that will be one lecture and then there'll be a pause and i'll tell 
you about the exam questions er and i'm happy to deal with any questions over 
over the course as a whole does 
that sound okay okay so there's the title climate change implications of crops 
vegetation and land use er diagram about climatic change in general er and 
we've done part of this over the last few weeks er that basically we talked 
first of all about emissions and concentrations of greenhouse gases and and how 
man's activities on the earth's surface and agricultural activities land use 
changes et cetera were affecting that er then last week we talked a bit about 
the effects on climatic change the observed changes in temperature sea level 
rise et cetera er so today i'm going a little bit across to look at the effects 
of impacts on on human natural systems er we can actually have a whole module 
on that no doubt at all very important topic er but i've basically restricted 
myself really to er bits about food and agriculture and and crops er 
obviously there is a circle here and we're not going to really get into how we 
adapt and affect and feedback into climate i'm going to concentrate on the 
effects of climatic change on on those uses just to summarise a bit these are 
the slides we had last week er er the I-P-C-C interdepartmental panel sort of 
prediction for climate change er for the next hundred years and er the thing 
that we're sure about are that C-O-two concentra concentrations are going to 
rise er over the next hundred years and certainly from where we are at the 
moment about three-sixty-five parts per million to a minimum of about five-
hundred and possibly up to 
eight-hundred pause /> er so that's going to be something that's going to 
affect plants and vegetation completely so C-O-two change is the one thing to 
think about er and then there's going to be changes in temperature again with 
great uncertainties er up to three or four degrees depending upon gra er green 
house gas emissions er and a corresponding increase in sea level rise but 
really for the point of view of er vegetation we got to concentrate on C-O-two 
temperature and the consequent effects upon rain fall and water 
balance er again this is just a recap from last week just to emphasise the 
changes that are likely to happen in the next hundred years or so and we are 
talking typically around three or four degrees increase in mean temperature in 
in our latitudes with the position about rainfall very much less clear okay so 
think now back to photosynth er to carbon dioxide and photosynthesis er and 
obviously as as i'm sure most of you're aware er s photosynthesis can be 
restricted by carbon dioxide and if you take most crop plants like wheat pause 
/> which have sort of C-three er metabolism for fixing carbon in in 
photosynthesis then there's a relationship between the rate of carbon dioxide 
fixation photosynthesis 
and the C-O-two level but this is inside the leaf er and basically as the C-O-
two level inside the leaf increases photosynthesis increases er the C-O-two 
level inside the leaf also links with the C-O-two level outside so basically 
for C-three plants which are most of the crop plants of the world an increase 
in carbon dioxide in the atmosphere is going to give an increase rate of 
photosynthesis er that's not actually true for C-four plants er which are 
mainly that as you know tropical grasses sorghum maize millet et cetera being 
the main crops er 
they have a sort of slightly strange or different i should say photosynthetic 
mechanism where they er effectively accumulate er carbon dioxide close to the 
sight of of photosynthesis er and the external concentration really doesn't 
make very much difference so increasing carbon dioxide in the atmosphere will 
increase photosynthesis by C-three plants but not by by C-four plants [cough] 
in theory anyway so individual leaves er if we're talking about er almost a 
doubling of C-O-two concentration by the end of the century that will give 
something like a fifty per cent increase in the rate of photosynthesis of 
individual of individual leaves er there there might be a small effect on C-
four species i mean the the the evidence is a bit divided some people say 
there's no effect some people might be small effect but it's certainly going to 
be less than ten per cent er so that seams good that that's a positive effect 
of climatic change in a way that that 
going to have increase rates of photosynthesis which again is a way of 
increasing the storage of carbon on the land's surface if we if we keep as both 
er but it's not quite as straight forward as as that er one thing that 
generally will happen is that most evidence seems to be that there's going to 
be an increase in stomatal resistance if C-O-two concentration increases plants 
tend to close their stomata a little bit er they don't need to have them so 
wide open for photosynthesis er now that's that's good in some ways because 
it'll probably reduce transpiration er reduce the rate of water loss so we'll 
get more dry matter produced per unit of water used er it's been called water 
use efficiency er we've mentioned before the the ration of of dry matter to to 
water use
er so that's sort of positive er but the stomata resistance may feed back and 
sort of cut down on this fifty per cent increase so you may get less less 
increase than that er but think back earlier on in the course we looked at the 
energy balance of leaves and and of crops and the energy got to go somewhere 
and if you reduce the transpiration then you're probably going to have an 
increase in in leaf temperature and er that may feed back into local air 
temperatures but when the warmer leaf temperature have a positive or negative 
effect on the leaf photosynthesis again is not really clear er it may be that 
there may be a negative effect of of warmer temperatures er so basically 
positive in C-three species but not necessarily that that clear now when you 
come t 
that really i'm talking about individual leaf you know an individual leaf 
exposed to different levels of carbon dioxide but when you come to a crop the 
effects are likely to be less than for a crop the individual leaf because not 
all the leaves as we talked before we looked at light not all the leaves are 
receiving the same level of light the old leaves at the bottom probably won't 
respond to to C-O-two et cetera er so most values show the effects are less for 
a crop than for an individual leaf but also leaves may actually sort of 
acclimatize to the changing in C-O-two level er those results i put up before 
are really sort of in experiments i think we're probably using measure 
photosynthesis er and it may be that plants adapt to the to the rates to the 
levels of C-O-two and reduce their rates over time there's a sort of s 
phrase that's used here about down-regulating that plants control their rate 
of metabolism er so there's been a lot of interest recently in actually looking 
at long term studies er of the effects of C-O-two changes if you expose plants 
to different levels of C-O-two for a long time do they change their 
photosynthesis er and of course plant growth is not just determined by carbon 
dioxide you've got other interactions particularly with water nutrients and 
temperature so what i'm going to do now is tell you bit about some longer term 
studies that've been going on looking at looking at these things er i don't 
know have you ever come across the term FACE at all anybody not in in this 
context er well it stand for free air C-O-two enrichment er basically if you 
think about what how do you experiments about C-O-two you could 
do experiments in the glass house er you could increase the C-O-two level in 
the glass house and look at the response as is done in commercial tomato 
production for ex example getting increased growth rates er but what what we 
really don't know is what's gong to happen to plants in the atmosphere outside 
so the idea of of these sort of experiments which are quite complicated only 
done in a few places in the world is to actually have experiments outside where 
er C-O-two enriched air is released over vegetation and continuously released 
so you've got plants or trees and things growing in increased C-O-two levels 
outside in real conditions er so there's a lot of sort of engineering going on 
to control the carbon dioxide er levels er and provide a stable elevated level 
of carbon dioxide and 
basically there should be no barrier to natural air flow so the wind et cetera 
can have its normal effect so the issue is not not affecting not affected er 
and basically these facilities have been built up mainly in in the states 
though there's been some work in the U-K er on a on a slightly smaller scale er 
but these ones are going to be er ones i'm going to show you in America er this 
is basically saying if we can't use full scale changes we need to use er bigger 
systems to look at but don't change the micro climate very much er so lets have 
a look this is this is a er called a FACE facility in er North Carolina er and 
these are the the facilities and these are circles about thirty metres 
wide er and these are just vertical pipes around here which let C-O-two in 
across the vegetation inside there er now obviously you've got to have 
different treatments and things so it all gets a bit complicated er building up 
er those sort of facilities er so they're quite a major investment er but these 
have been going in the states for er since the sort of mid-nineteen-sev er mid-
nineteen-nineties and built up some some useful results er so er th these are 
some results fr from that particular one looking at er er it's pine forest er 
in in U-S-A and you've got a control plot where the normal ambient C-O-two 
level three-sixty-five parts per million roughly 
er and they increased that by two-hundred so the the treatment there is is two-
hundred parts per million i'm sorry two-hundred parts per million extra five-
sixty five-sixty-five parts per million er so that's experiment er is still 
running but they've only actually got the results up until two-thousand sort of 
published so far and do you remember back in one of the earlier works we talked 
about net primary production N-P-P how much production as a forest or something 
will produce over a year so this is what these figures are grammes per metre 
squared per year er and basically there's variation from year to year er 
natural other factors water rainfall solar radiation temperature et cetera but 
as you can see in each year 
so far er the the trees receiving the higher level of C-O-two have produced 
more more biomass er somewhere between twenty and thirty per cent er more 
increase er and then this supports the fact that over time as the C-O-two 
concentration in the atmosphere has gone up historically then certainly 
suggests that this this type of forest will have been accumulating biomass at a 
at a bigger rate we talked about over the last twenty years how we think that 
the net the earth's surface the the vegetation of the earth's surface has been 
a net 
sink for C-O-two taking up C-O-two so this is part of the story plants 
responding to to C-O-two concentration does that seem okay at the moment is 
that er okay we'll go a bit further on those results then er so you so far 
there's been an increase in dry matter in a fraction over four years er but the 
sort of papers and that suggest that this may well c carry on but may not be 
sustained if nitrogen becomes limited obviously nitrogen is involved in in 
growth processes and can't necessarily er sustain increased rates of C-O-two if 
you don't add any more nitrogen er either naturally or not now there's again 
concern in that we're increasing the global nitrogen cycle so maybe that's 
happening anyway er and there's need for measurements of nitrogen then but at 
the moment it does seem to be sustained and carried on er 
so there's er no evidence here of of acclimatization of of plants down 
regulating the photosynthesis er there's also over those four years no matter 
no difference in dry matter partitioning the increased dry matter's going to 
leaves roots trunks et cetera in the same proportions as it was before er so 
you're just getting bigger trees but they're in the same proportions er there's 
also s no difference in stomatal resistance or or water use they've also 
measured those things there so basically these trees are producing more dry 
matter er for the same amount of water so they've got a greater water use 
efficiency er so this seems a fairly straightforward response it's it's 
behaving almost in expects as you'd expect it to er for simple rates of 
photosynthesis er a again in these experiments they measure all sorts of things 
and if you remember back er in about week five we er said that one way of 
analysing
crop growth was to think about the dry matter produced grammes per meter 
squared in this case per year er as being made up of two things the absorbed 
radiation the the crop or the trees in this case captured in the sun er and the 
er thing called the radiation sufficiency which was basically how you turn the 
absorbed radiation in in into into dry matter er how many grammes of dry matter 
you get per mega joule of radiation absorbed er what these a are data from from 
th those trees er and essentially this bottom one is er three-sixty-five parts 
per million the normal environm the normal environment er and the five-sixty-
five one here and you can see that over time there's really been no difference 
in the amount of radiation intercepted that's still still constant er 
they're trees that've got a reasonable leaf area they they've got a leave area 
in about three to four so they're capturing a reasonable amount of light er and 
there's no difference here the difference is in the radiation sufficiency er 
which is what you'd expect really that's the that's the photosynthetic 
processes the conversion of radi er radiant energy into dry matter er that's 
been increased by by photosynthesis er so that's one example of of how the 
radiation we used to understand the experiment is that okay so far okay er so 
that's one bit er another FACE facility is in the University of Arizona er 
where they did experiments on wheat er so again these circles with C-O-two 
enrichment er coming in across the the individual plots in there er again a 
reasonable distance between the plots so avoids cross contamination and things 
like that er what do they show for wheat well that's a bit 
more complicated really er they had er used a fifty per cent increase in 
carbon dioxide so you have plants at normal er atmospheric carbon dioxide and 
ones with fifty per cent increase er and there was a strong interaction between 
carbon dioxide and water use er the water use was reduced by about six per cent 
from well watered crops so there was there was some reduction in in stomatal 
resistance er stomatal stomata were probably closing a little bit er but in 
terms of the photosynthesis er when you had crops with adequate water well 
watered crops you got something like about a nineteen per cent increase er in 
in in photosynthesis for for the canopy er now you might expect on an 
individual leaf something like thirty per cent but it as i said earlier it's 
probably less for an individual for a for a whole crop so wheat er C-three 
species getting an increase in in canopy photosynthesis from C-O-two er but 
actually doing better 
when you've got water deficiency er that when the crop is short of water the 
er the increase in C-O-two is able to compensate for that and and boost up 
rates of photosynthesis er so you've got a much greater increase un under water 
stress er so thus suggests that plants may the combination of er high C-O-two 
an and reduced water might be there might be some compensation there but it 
certainly in in wheat er but obviously when you come on to future predictions 
of what's happening to crops what's going to happen about er water er around 
the world is is very important er okay so that's looked at C-O-two er and some 
interactions with water but in the in what we think's going to be the world in 
the next next century er any increases in carbon dioxide are going to be 
accompanied by increases in 
temperature er generally on average er you know we talked about mean 
temperatures increase increasing but in general there's going to be increase in 
temperature so we need to think about that those interactions er and we 
remember we struggled a bit with thermal time earlier on this product of 
temperature and time which really controls the development of crops so warmer 
temperatures mean quicker development er so present day varieties will mature 
quicker and have less time for photosynthesis er do you remember we did the 
thing about maize and altitude in in one one of the lectures there er so what's 
going to happen er er when when temperatures increase er in combination with C-
O-two levels well there've only been experiments on wheat there were some done 
here actually in and at Rothamsted experimental station er the ones here they 
they grew plants in plastic tunnels with big heaters at one end er increased 
the C-O-two level and got a grade of temperature went down the tunnel so you 
could look at the effects of temperature and C-O-two concentration and 
basically in terms of yield and things increases due to carbon dioxide were 
cancelled out or doubling of carbon dioxide was cancelled out by about a two 
degree temperature increase er because er the temperature increase meant the 
the plant growth was ever quicker er and this was sort of illustrated by sort 
of crop modelling if you like er i mean crop models are basically trying to 
people trying to predict how crops grow and they're based on things like 
thermal time and radiation efficiency er and these are some of the results
they expect for a wheat crop this crop labelled nineteen-eighty-one refers to 
typical conditions a in in the nineteen-eighties so that might be total dry 
matter of a wheat crop er over time giving you something like er twenty tons 
per hectare so it's a pretty good crop then bringing those sort of results 
we've got in if you double carbon dioxide er you get a higher rate of 
photosynthesis and get more dry matter er so that's a doubling of carbon 
dioxide but you also accelerate if you if you then have a three degree increase 
in temperature er you accelerate 
development so you get the dry matter er and you get it quicker that that all 
seems fine you getting more dry weight and an in a quicker in a quicker time er 
but that then leaves little time for the grain to fill er in terms of grain 
weight er basically what you tend to happen is you accelerate the grain filling 
process and you don't get a lot enough time to fill grain so in terms of grain 
yield you get relatively difference between the conditions here and the 
conditions there er so this rapid development of of of cereal crops er sort of 
cancels out er the er the effect of s carbon dioxide and you don't get much 
effect upon upon yield does that seem to make any sense to people or not maybe 
ok er what what about other crops er well things like er vegetative crops er 
things like sugar beet and potatoes where you're not actually growing them for 
seed for grain er they're not so restricted by developments they will have 
yield formation over a longer period er continue growth along that 
so basically the effects of carbon dioxide doubling there tend to be greater 
than the effects of negative effects of temperature er so provided you've got 
water you tend to evidence seems to be that you'll get an increasing yield on 
on those sort of crops okay so we're starting to get together a picture of how 
carbon dioxide and temperature er inter influence yields of crops one thing 
that's going to obviously differ in in climatic change is distribution of crops 
er it's slightly illustrates the point quite quite nicely er this is maize in 
the U-K er now we don't really grow maize for grain er like they do in France 
grain for feeding of animals where you actually harvest the mature grain er 
because basically the season's really too too short er well we grow the maize 
for silage where we harvest the whole the whole crop and obviously we grow 
things for sweetcorn but sweetcorn's not mature grain it's an in between and er 
[cough] around the the end of well eighteen nineteen-eighty-seven nineteen-
ninety er in terms of temperature the limit for grain maize is pretty well the 
south coast it can be grown in in Fr in northern France but not so much in the 
U-K 
er an increase of half a degree in mean temperature would put the limit up to 
here one-and-a-half here and three degrees would take it up in into Scotland 
because temperature's the limiting factor based upon this thermal time er 
silage maize limit there er could could move quite appreciably er the other 
point about here is on here are some particularly er nineteen-seventy-six was a 
particularly hot year and before we got into the late nineteen-nineties and the 
warmest years of the millennium er and in that year the limit stop up here 
already a cold year nineteen-sixty-two it was down here so we've already 
experienced individual years some of the fluctuations of the same sort of size 
er as things that we're we're getting er but basically even a sort of one or 
two degree limit a change in temperature will vastly increase the range in 
which various crops can be grown going to be a lot of changes in in in crop 
composition and and and into grow in different places er what sort of yields 
could you get for for maize and i've put this in to illustrate one particular 
point er that these are estimated yields of forage maize in the U-K er 
and basically the darker areas are the highest yielding areas at the moment er 
you can't get any yield of maize and this study looked at what would you what 
would happen to maize yields if i'm sorry it's off the top of the screen here 
but it's increase temperature by two degrees and rainfall by ten per cent er 
very simple er adjustment in in er in climate do you see that the mean 
temperature's gone up by two degrees and rainfall's increased by ten per cent 
there's no effect of carbon dioxide in here and er the yields basically 
increase er and particularly increase in in the midlands and the west of of the 
country but if you increase 
temperatures by two degrees but decrease rainfall by ten per cent you get a 
lot of these lighter colours er and the the increase yield is is er disappeared 
and this is one of the great uncertainties really is that we not really sure 
what's going to happen to rainfall in in in the in the coming centuries and 
things like maize et cetera are very sensitive to to to rainfall plus or minus 
ten per cent there's almost nothing you get a complete change of yield pattern 
er between those two conditions so got to be very careful about what you read 
and believe because knowing what the future rainfall is going to be is very 
important in terms of er not only agricultural crops but in terms of natural 
vegetation as well er okay some sources of information about er climatic change 
and impacts and i've stuck this one in here er 
U-K C-I-P United Kingdom er climate impacts programme er it's it's quite a 
substantial activity er funded by DEFRA er based really at the university of 
Oxford er provide a lot of information on put up the website a b a bit later on 
er one of the things they did er and i put this in really for those of interest 
in some ways but it is interesting er they commissioned a report on on what's 
going to happen to gardens in the next millennium er sorry the next hundred 
years er not only domestic gardens but also er you know stately homes and 
things like that and er had grow here so who're responsible for this this 
report er and produced a few fairly what i think fairly interesting figures 
some of us're looking back at the climatic records er this is the central 
England's temperature record er which we said before er it goes back to about 
seventeen-seventy er and these are the number of hot days er days above twenty 
degrees in a year er and you can see that 
there's er a general general increase trend this is like a smooth curve going 
through here and the colour's just to highlight the areas above and below er 
this is the nineteen er sixty-one to ninety average er so over the last few 
years the number of hot days has increased er and these are the number of of 
cold days er er linked in to frost occurrence we saw this before but certainly 
that occurrence is is is much less in the last part of this century than than 
back in the previous centuries and and those are things that are relevant to to 
to garden plants the length of the growing season er we talked back in earlier 
times about thermal time and roughly er growing season is is roughly defined 
for time when temperature is above er is is greater than five degrees five 
degrees five degrees centigrade roughly speaking so this is the number of days 
in in a year in central England er that the the growing season has been er the 
temperatures have been above five degrees er the average in sixty-one to ninety 
is two-hundred-and-forty-two days er for central parts of England er and you 
can see that how the sixty-one to ninety average year er is higher than the 
last er a-hundred-and-fifty years and how apart from a little dip er in in the 
sort of seventies 
we've gone up er with growing seasons increasing in that in length and that's 
again predicted to continue linked with that er are some some li interesting 
data actually recorded from upper one person's garden in in in Norfolk er but a 
lady's been growing plants er in in the same place for sort of forty years and 
has kept detailed records of of flowering dates and things er so these are 
flowering dates of things like primrose daffodil et cetera er and just showing 
er how in general flowering dates are advanced over the last fifty years er 
primrose actually flowering first flowering in November er daffodils going from 
March back into February er and these are the changes per 
decade so there's no doubt that growing seasons and times of things are are 
changing er and and er as temperatures increase er i haven't got time today at 
all to look at natural vegetation in any great detail at all er but obviously 
many species are temperature dependent and in general most natural species will 
probably move northwards in in a very general sense er until they run out of 
space er and and can't go any further er and these are again people are are 
producing models of how species distribution er be affected by climatic change 
most are driven by temperature 
but some impact of water er so this this is the sort of present distribution 
of br beech trees in in in the U-K er the Chilterns for examples but restricted 
to the southern areas er and these are various scenarios depending what will 
happen in two-thousand er or could happen by two-thousand-and-twenty er 
depending upon the rate of C-O-two emissions a relatively low scenario or a 
high scenario and by two-thousand-and-fifty er with the same scenarios and 
basically er the the evidence is that there will be a northward movement say 
it's not going to occur to all species but that's an example of what people are 
people are doing er okay i want to focus down a little bit more on on on U-K at 
the moment and you may or may not have come across this report and i'll show 
you how to get it on the web later on er that obviously climatic er change is 
is a great concern and er these people all together the er 
U-K climate impact programme DEFRA the Tyndall centre is actually er a centre 
for climatic change and research which is based at at a few universities 
particularly East Anglia and the met office have been doing work on scenarios 
for the U-K now these may not show very clearly here but er er basically what 
they they do is take big global climate models we talked about very briefly 
last week er which give you the big picture of of climatic change in the future 
and then they sort of con scale them down to smaller scales er by various sort 
of statistical methods er which we didn't really worry about was that an 
attempt to give 
more detail at at a local scale and er as i say there's a there's there's a 
reference there where you can find the whole report er if you want to the U-K 
er climates impacts programme er and the sort of things that it er says the g 
change you're going to get er are things like this now this is quite 
interesting looking at winter er what we've got here are are winters this is 
this'll be
if you like the mean winter and then we we have warm winters and cooler 
winters er or wetter winters and dry winters and the black dots are what we've 
had er over recent times over er last twenty or thirty years er we've had some 
winters that are er sort of drier and colder than than the average er or we 
have warmer wetter winters but not particularly so the the circles er sorry the 
the red symbols er are what's likely to happen by the time you get er into two-
thousand-and-twenties and two-fifties and the eighties er and but
with er various bits of s of scatter and essentially the the implications are 
for what we talked about last week that we're going to be having warmer and 
wetter winters er and considerably warmer and wetter er er by the end of the 
century if you look at summer er the points tend to be all cluttered round 
there that we tend we've had dry summers and wetter summers but we don't 
actually have so much variation in temperature over over the summer as a whole 
er but that again is is likely to change and all the predictions are remember 
we said last week of a decrease in in rainfall in the summer and the increase 
in temperature so the evidence seems to be for the U-K that we are certainly 
moving towards er warmer drier summers which will have obviously effects upon 
natural vegetation crops water resources and things like that any any thoughts 
about that any questions about that does
it good for going to the beach but then again not so good for other things er 
again i i don't expect you to look at these in in in any any detail er but 
these are the sort of level of detail that people are now modelling the 
climatic change of the U-K you see the U-K is made up of little little grids er 
and this is looking at winter rainfall er and then summer rainfall over here er 
and this is er looking at what they think is a is a reasonable scenario and 
given the present rate of C-O-two emissions and things what's likely to happen 
and basically er anything 
green or blue means more rainfall er and anything yellow down to red brown 
means less rainfall so er and sorry what i didn't say i can't see here quickly 
this top line is for sorry for re relatively low emissions and high emissions 
of C-O-two and you know we may be somewhere in between but it this quantifies 
the effects and the important thing is that er in terms of winter rainfall it 
seems that most of the effects are going to be concentrated in the in the south 
and south east 
of of of of the country er and the same is going to be true in in summer 
rainfall that the summer rainfalls will decrease everywhere but er there's a 
more a tendency of bigger effects in in the south er er and particularly as you 
get towards the end of the century so these are the sort of latest predictions 
that people have got and and people are trying to think of the implications of 
of these things for for for life in the U-K er temperature again er all the 
colours here are positive er nought's down here er going up to f four and a 
half degrees five degrees increase in in temperature er and obviously
high emissions have a bigger effect er but again there's there's a er a a 
tendency again for the for the well for England i suppose and particularly for 
the south east er to have the biggest effects er moderated in in in in in in in 
in other places er soil moisture content this is this is er er very small you 
can r read the details on on the web if you want to but essentially again it's 
er getting drier essentially in in in in in the average soil moisture content 
er thermal growing season i s showed you figures how that've changed over time 
already er and again we're talking about fairly long changes er big changes er 
that increases er i mean the lowest colour er i mean er this is for two-
thousand-and-eighty so i suppose it's it is the end of getting towards the end 
of the century er but i mean the smallest changes here are something like an 
increase in thirty thirty thirty-five days er under low
emissions er and er under high emissions basically temperatures being probably 
warm enough for substantial crop growth throughout throughout the year so again 
it's going to have a major effect upon upon vegetation and and cropping er 
people are doing all sorts of different approaches to try to predict the 
effects of of climatic change er one one of the nicest studies that i've seen 
recently is is this one from Ireland er so i thought i'd stick it in to give an 
idea of what people actually do it uses the same sort of ideas as as before er 
a big general circulation model and then coming down to give you more local 
detail er and it uses something called weather 
generators er the idea there is that if you sort of estimate the the monthly 
temperatures for instance or the monthly rainfall you've got an idea of how 
many days it's going to rain you can generate the daily artificial daily data 
if you like to simulate typical climate patterns quite a bit of research 
getting into that sort of area er how you take sort of monthly data and guess 
at what the daily data will be so it all adds up together if that makes makes 
sense er because obviously it matters a bit er you know if you if you get sixty 
millimetres of rain a month does that come in one storm 
er which has probably nasty effects and damaging effects or does it come in in 
ten nice gentle rain days spread over the month and things like that so there's 
work going on there er so it tries to estimate daily data and then uses crop 
models er these are a set of crop models that are very widely used throughout 
the world to estimate yields er so what they've done is to try to 
look at patterns of rainfall in er in Ireland er and they they sort of tested 
it by going back to predict the past climate if you like er this isn't real 
data it's predictions from a model with sort of run from from from early on in 
in in time er and don't worry about the details but basically er January these 
examples of January rainfall basically getting wetter in Ireland the the darker 
colour the the more rainfall 
but summer rainfall er again decreasing consistent with the U-K er but what 
does that do to to crop yield oh that's that's temperature sorry er again these 
are all positive temperatures er er but basically lighter colours here 
increasing temperatures in in summer and increasing temperatures in in in er 
winter but then using that data er you can basically run the crop model to 
estimate the yields that you'd get 
for the crops er in each of these little squares you know so each square 
basically has got its own climate er generated and produces its own estimates 
in yield er so this is a pattern er nineteen-sixty-one to ninety and basically 
these conditions er given that barley is is basically grown as a winter crop er 
so sown in the autumn and harvested later on in in in in the s in in in the 
summer er 
you're actually tending to get increases in yield in in in barley predicted er 
in in in Ireland potatoes without irrigation er which are quite widely grown in 
Ireland at the moment er the colours get lighter basically as time goes on 
because the summer water shortage becomes more and more er important and and 
restricts the growth 
er of of of the yield so don't worry about the details now i've really put it 
just put it in to show you what people are doing how people are trying to im 
model predict the impacts er but to my mind it's very crucial that the the the 
the assumptions about rainfall are are are good and i've still got a big 
question mark over that er you know you still have to trust the the the models 
or whatever er and they're certainly getting better er they're doing very well 
but the results are very sensitive to to to to rainfall er as i say we we could 
spend the whole module 
looking at the effects of climatic change just some some very general thoughts 
about the the likely effects upon agriculture generally in in in U-K whatever 
different crops basically being grown in different places er is the obvious way 
of adapting er and er er you know that in some ways may actually give us more 
diversity and more things that we can actually grow there's probably going to 
be more autumn sown crops because the winter conditions are going to be warmer 
different 
weeds likely to to be there among the growing seasons and summer water supply 
may well be a problem er there's going to be a lot of work about efficient 
irrigation and things to to make use of water resources er so er and in these 
sort of impact studies you can read much more about these these particular 
details er rainfall well the predictions all seem to be reduced summer rainfall 
er will effect water supply and warmer temperatures will really increased 
demand and i know that the er water companies and and people are very concerned 
about possible demand in in in two-thousand-and-fifty whatever er and need in 
increased 
reservoir capacity er to keep the the the winter water er available er a 
possible adverse effect if water flows in rivers in the summer are cut down and 
they adversely effect quality pollutants don't get so dilu diluted and things 
like that in in effect quality er and fairly obviously heavier more intense 
winter rainfall can give increased flooding et cetera 
and there's evidence over the Europe that these things have become more 
frequent in in in in time er i'm not going to say much about sea-level rise er 
but i put here figures from the er the U U-K climatic impact re report er and 
it it's not quite a straightforward picture er we talked about sea-level rise 
er you know because of the thermal expansion of the ocean and things like that 
er we also have to bear in mind er that land's also rising as well er in well 
in in in in
in parts of the U-K er there're geological movements er here in in in 
millimetres per year er so Scotland's going up very gently er and other parts 
are going down et cetera er and you have to take that into account when you 
look at the effects on on on actual practical sea-level rises so these are the 
sea-level rises that are being predicted for the various areas of the U-K er 
but again er you know if we if we take er where shall we take take eastern 
England which is 
somewhere that people are often very concerned about that's actually sort of 
sinking down a bit but we've we've still got a big range between twenty-two 
centimetres er and eighty centimetres depending upon the different emission 
scenarios er so again a great cause for concern er and this this is very much a 
lower limit of i think er of what is likely to happen er so again people 
looking at you know precautions wh can't spell coastal can i sorry deliberate 
mistake er increased coastal flooding coastal erosion and things like that and 
things to be concerned about right that was really concentrating on the U-K er 
just to finish up a couple of slides about er world 
production er this is looking at er U-K production sorry cereal production in 
the world under different er climatic change models er you needn't worry about 
these these are three different models one one's the U-K model and whatever er 
because the the models don't necessarily agree but the question is 
do you get consistency on on on on the output et cetera and er what this graph 
is is basically looking at is developed countries er developing countries and 
and the world total and overall er in terms of cereal production the climatic 
effects only which are are basically temperature and rainfall the the estimates 
seem to be that total developed world cereal production should go down but i'm 
sorry i if you can't read the detail but er the climate effects are are 
rainfall er and temperature the the 
effects of carbon dioxide increase will probably turn that into into a 
positive effect er so increased temperature reducing yield but the carbon 
dioxide effects generally balancing that although depending on which climate 
scenario you you you pick up er you may have a a negative effect or positive 
effect er but then there are various 
things that we can do er this is a dash er called adaptation level one which 
are things like er changing the crop variety changing the planting date er er 
and the amount of water applied for a level a areas already irrigated er so we 
can do some things to to maintain cereal supplies er or we can grow go on to 
further adaptation by growing different different varie different crops 
you know maybe growing er well say more maize instead of instead of wheat and 
things like that er and other things but i suppose the the basic picture to get 
from from here is that er that in theory the developed world can probably 
maintain its food supplies its cereal supplies by a adapting changing varieties 
moving things around er that's much less harder to do or much harder to do in 
developing countries where the scope for 
adaptation is less er adaptation may reduce things but the the climatic 
effects particularly in the tropics would seem to be generally fairly negative 
and that's a a position that we need to need to think about er in terms of 
world total well maybe we can keep food supplies together er at er the same 
sort of level er but er you know there's there's a tale of two two worlds there 
if you like and er the world's got to be able to 
come to terms with this particular problem in in in the near future er again a 
couple of international studies to show that people are looking at these things 
around the world er the the current distribution of beech trees in in in north 
America er and how that's likely to change under different predictions of of 
climatic change in the next er er fifty years or so er simple things like again 
i've just picked out one individual crop this is coffee er quite an important 
crop in in parts of Uganda er coffee doesn't really like warm temperatures er 
there's a lot of material out there that that you can read er you don't really 
need to read for for boring things
like the exams in this course and things like that er you know the hand outs 
and some of the particular things i'll i'll talk about exams a bit later on er 
but these are some of the the important sites for climatic change er the grid 
what we we we've referenced before er which is the United Nations environment 
programme er that one we had up er we had sort of climatic graphics with last 
week climatic research East Anglia is is is quite an important one met office 
er U-K World Meteorological Organization in in Switzerland er is W-M-O er this 
is the United Kingdom er climatic impacts programme the Tyndall centre 
er again is set up for for mainly for U-K climate change and again DEFRA has 
has got an important web site now for for climatic change information er so i 
hope i sort of took your interest and go away and have a look at some of these 
things because it really is a a substantial problem we all challenge shall we 
say that's going to affect you in your lives much more than me in in respect to 
mine i suppose er okay any any thoughts or questions or cameras are very good 
at shutting people off you pessimistic about the future optimistic about the 
future or what 
sm1360: we die 
nm1359: sorry yeah there's there's there's a lot of uncertainties there but but 
the science is is really focusing er it's er it is a major major concern area 
er and i i hope what you can see is some of the sort of basic principles that 
we looked at early on in the course the sort of energy and exchange and er net 
radiation things like the microclimate modification radiation is that they've 
all got a part in understanding and predicting what's going on and i think 
that's quite quite important okay er well er any any other questions on this or 
not yeah 
sm1361: er in page six er this one here about the natural variation in the er 
red one report to come winter and summer 
nm1359: yeah 
sm1361: er y there's some where there all dots seem to be all together of what 
the er natural ones 
nm1359: er yeah i'm sorry you i should have warned you that 
sm1361: i don't know how i i i can see how er the er er 
nm1359: yeah 
sm1361: i can see how the they could they could manage to get the the red ones 
what to come on the left hand side by looking at the black ones but i don't see 
how to get the black ones all come together they might manage to get somewhere 
nm1359: so er are you do you mean do you mean these ones or 
sm1361: other side 
nm1359: so this one 
sm1361: looks like the ones which they've actually got er 
nm1359: yeah 
sm1361: what to i i don't see how they got the er ones that are all spread out 
nm1359: scenarios for what will happen in in two-thousand-and-twenty and what 
it's basically saying is that that temperatures temperatures are going to be 
warmer and summers are going to be dryer er er i'm not answering the question 
there i think but er so that's two-thousand-and-twenty and then 
two-thousand-and-fifty we'd might be down here two-thousand-and-eighty we're 
going to be down here er so the these are different estimates from different 
different sort of scenarios so there's variability er what he's really saying 
is that by two-thousand-and-twenty we're probably going to be experiencing 
summers that we haven't experienced before 
sm1361: well it 
nm1359: er whereas here there is some overlap er so some of the winters er 
in in two-thousand-and-twenty won't be that different from winters we've
had in recent times er you know we we've had things of this amount of warmth 
and this amount of of of rainfall er it's later on two-thousand-and-fifty when 
we're going to get into er even warmer and wetter er conditions er is that a 
sort of answer 
sm1361: think so 
nm1359: yeah