climate change Flashcards
(140 cards)
1
Q
lec 1: RESPONSES OF ORGANISMS
Atmospheric CO2 through geological time:
A
ice ages (low CO2), warmer interglacial (higher CO2) for 800,000 years never higher than 300ppm (NOAA 2008).
2
Q
lec 1: RESPONSES OF ORGANISMS
Atmospheric CO2 in recent time
A
: large growth in CO2 emissions. Levels stable until 18th C (industrial revolution 1850s), current 427ppm (NOAA daily measurements since 60s)
3
Q
lec 1: RESPONSES OF ORGANISMS
Rubisco:
A
important enzyme in fixing carbon, dual catalytic nature, carboxylation vs. oxygenation is largely dependent on CO2/O2 ratio. CO2 is key (O2 considered constant). The higher the temp the more difficult for rubisco to distinguish CO2 and O2 (higher energy, faster particles) DIAGRAM
4
Q
lec 1: RESPONSES OF ORGANISMS
Change in net photosynthesis with changing [CO2]
- C4 plant
A
minimising amount of photorespiration happening while photosynthesis is happening (higher C uptake)
5
Q
lec 1: RESPONSES OF ORGANISMS
Change in net photosynthesis with changing [CO2]
- C3 VS C4
A
DIAGRAM. Carbon pump costs energy, if enough CO2 better to be used to photorespire, if not enough worth investing as increases CO2 available.
Caemmerer 2012
- C3: struggle at low CO2 but keep increase in biomass (RICE)
- C4: fair well at low concs. Reach max growth earlier, more likely to find in warmer environ. Investment worth it (SETARIA VIRIDIS)
6
Q
lec 1: RESPONSES OF ORGANISMS
Interactions between CO2 and temperature
A
CO2 fertilisation effect (plants grow better under higher CO2). In C3 plants this depends on temp (higher CO2 concs at higher temp to observe same growth rate) (Campbell 2005)
7
Q
lec 1: RESPONSES OF ORGANISMS
Stomatal conductance and increasing CO2
A
: rising CO2 induces partial stomatal closure therefore decreases transpiration.
- C3+C4 respond differently. C4 close their stomata more under all circumstances (impacts water loss and carbon gain) (Sage 2003)
- FACE experiments (BIFoR)
8
Q
lec 1: RESPONSES OF ORGANISMS
Water dynamics in response to CO2 gradient
A
if stomata close more, loose less water, can see water efficiency increases with high CO2 (Polley 2002)
9
Q
lec 1: RESPONSES OF ORGANISMS
High CO2 effects during heat and drought
A
enhancement of plant performace at high CO2 reduced during extremes (no cooling) (Osborne 2016)
10
Q
lec 1: RESPONSES OF ORGANISMS
Effect of CO2 variation: growth responses of plants to past CO2 change when soil fertility is adequate:
- growth responses
A
high carb level in plants cause feedback signals that reduce expression of photosynthetic genes (ABA high, cytokinin low, nutrients low
11
Q
lec 1: RESPONSES OF ORGANISMS
Effect of CO2 variation: growth responses of plants to past CO2 change when soil fertility is adequate:
- in absence of phosphate fertalizer
A
- In absence of phosphate fertiliser plants do not respond to CO2 (white lupine, Campbell 2002) (45 studies have shown this)
12
Q
lec 1: RESPONSES OF ORGANISMS
Effect of CO2 variation: growth responses of plants to past CO2 change when soil fertility is adequate:
- in absence of N
A
- In absence of enriched N growth insensitive to increased CO2 (need N to process C)
13
Q
lec 1: RESPONSES OF ORGANISMS
Response of photosynthesis
A
variation between species, enhancement or downregulation, limiting factors (soil)
14
Q
lec 1: RESPONSES OF ORGANISMS
Biological nitrogen fixation:
A
N2 –> CHN2, main natural source of N for ecosystems,
principle source from root nodules of higher plants (legumes, tropical grasses) dependent on carbon status of plant.
15
Q
lec 1: RESPONSES OF ORGANISMS
EFFECT OF CO2 ON N FIXATION
A
dependent on plant, some decrease fixation with long exposure to increased CO2 (nutrient deficiency) (Reich 2006)
16
Q
lec 1: RESPONSES OF ORGANISMS
INSECT SENSITIVITY:
A
: months can sense CO2, more difficult to find food source (prickly pear) in high CO2
17
Q
lec 1: RESPONSES OF ORGANISMS
OCEAN:
A
rising CO2 lowers pH and carbonate supply (IPCC, 2013
18
Q
lec 1: RESPONSES OF ORGANISMS
CORALS
A
reach saturation of carbonate
(orr, 2005).
19
Q
lec 1: RESPONSES OF ORGANISMS
MARINE ANIMALS
A
marine animals problems with building skeletons (orr, 2005
20
Q
lec 1: RESPONSES OF ORGANISMS
SEA URCHINS
A
sperm production and motility harmed (Haverhand, 2008)
21
Q
Lec 2: overview
weather
A
is the current atmospheric condition
22
Q
Lec 2: overview
climate
A
general weather condition over a long period of time
23
Q
Lec 2: overview
climate change
A
changes in behaviour of the weather (+ climate) over longer time scales
climate has shown rapid warming trend in last decade (NOAA)
warming evident from several observations
24
Q
Lec 2: overview
increasing temp. early evidence
A
1st described by g.s. callendar (1898-1964)
already ascribed it to CO2 from fossil fuel combustion
amateur but formulated coherent theory of IR absorption by trace gases
25
Lec 2: overview
temp patterns for various climatic zones + of earth
fuel combustion has added 150,000 million tons of co2 to aur over past 1/2 Cent
increase by more than 0.2 C between 1890-1935
26
Lec 2: overview
warmest years on record
2019 and 2023
NOAA
27
Lec 2: overview
global warming
more areas warming than cooling
NOAA 2020
- temp has increased average 0.08 C per decade since 1880
average rates of increase now x2 this (0.18C)
28
Lec 2: overview
Intergovernmental panel on climate change (IPCC)
international body for assessment of climate change
- established by UNCEP and WMO in 1988
29
Lec 2: overview
IPCC 2014 quote
"human influences is clear, anthropogenic emissions of GHGs highest in history"
unprecedented changes
costs are huge: US 20 major climate related disasters costs exceeding 1 billion (2021)
30
Lec 2: overview
GHGs
water vapour, co2, methane, nitrous oxide, ozone
31
Lec 2: overview
GHGs
methane
released by ruminants (cows, sheep) as by products of gut processes and rice paddys
large part of GHGs comes from how we grow food (growing pop.)
32
Lec 2: overview
GHGs
nitrous oxide
volatisation of nitrogen (nitrification and denitrification) release N2O as side product
mainly from fertiliser applications
33
Lec 2: overview
GHGs
agriculture
agriculture plays a major role in GHG emissions
area that can be reduced (still less than fuel)
34
Lec 2: overview
GHGs
scenarios IPCC
representative concentration pathways
prediction of future
- what will happen if we get different levels of CO2
no cutting will result in RCP8 (worse case scenario) and RCP6
- current trends is RCP8
35
Lec 2: overview
GHGs
scenarios IPCC
adaptation
deals with climate change
36
Lec 2: overview
GHGs
scenarios IPCC
mitigation
emission reduction
e.g. paris agreement
37
Lec 2: overview
ecosystem
- heterotrophs
decomposers
bury carbon in soil (sequester)
soil fauna, fungi, bacteria
38
Lec 2: overview
ecosystem
energy and matter flows
39
Lec 2: overview
ecosystem
- photosynthesis
consumes co2
carbon fixation and assimilation
has benefitted from increased co2
40
Lec 2: overview
productivity
measured in g biomass per year + ha
41
Lec 2: overview
productivity
gross primary productivity
= c fixed in plant (photosynthesis
42
Lec 2: overview
productivity
net primary productivity
GPP - plant respiration
43
Lec 2: overview
productivity
net ecosystem productivity
= NPP - heterotroph respiration (animals, decomposers)
44
Lec 2: overview
RAVEN 2022
cannot just be optimistic
45
Lec 2: overview
road map to net zero
mitigation: carbon accountability, land use change
the potential for new production systems
adaptation: barriers; adoption; integration; improved genetics
46
Lec 2: overview
climate change + european agriculture
among the most exposed sectors to climate induced changes
as a primary production sector farming activities are dependent in the natural environment (weather, pollination by insects, availability of water + nutrients in soil)
achieving net zero status requires action from all sectors (incl. agriculture) which is expected to account for 1/3 of total EU emission by 2050
47
Lec 2: overview
UK argi-food statistics (CIEL 2020)
total agricultural area
in 2018 total argicultural area was 19 million hectares
77% of total land cover
60% live stock
31% crops
5% woodland
48
Lec 2: overview
UK argi-food statistics (CIEL 2020)
animals + FGD value
over 9.5 million cattle, 33.5 million sheep, 5 million pigs, 187 million poultry
FGD value- £12 billion per year
49
Lec 2: overview
UK argi-food statistics (CIEL 2020)
imports, exports
imports:
£10 million meat + milk per year
exports:
£4 billion / ~60-70% self sufficient
50
Lec 2: overview
UK argi-food statistics (CIEL 2020)
UK's gross values added
agriculture makes up 0.6% of UKs gross value added
within a wider food sector (6.6%)
51
Lec 2: overview
UK argi-food statistics
emmisons
agriculture responsible for 10% of the emissions in 2018
(BIES 1990-2018)
52
Lec 2: overview
UK argi-food emissions (BEIS 1990-2018)
total
10% total (2018)
53
Lec 2: overview
UK argi-food emissions (BEIS 1990-2018)
methane
56%
54
Lec 2: overview
UK argi-food emissions (BEIS 1990-2018)
nitrous oxide
31%
55
Lec 2: overview
UK argi-food emissions (BEIS 1990-2018)
co2
12%
56
Lec 2: overview
UK argi-food policy
life after CAP
bill provides legistation framework for replacement of agricultural support schemes
provides range of powers to implement new approaches to form payments and land management
57
Lec 2: overview
UK argi-food policy
environmental land management scheme
the primary mechanism for distributing the funding previously paid under CAP
58
Lec 2: overview
UK argi-food policy
scotland
has set net zero target by 2045 under the climate change act 2019
59
Lec 2: overview
UK argi-food policy
welsh gov.
has set target for the sector to decrease its GHG emissions by 63% from baseline (1990) levels by 2030
and become net zero by 2050
60
Lec 2: overview
UK argi-food policy
Northern ireland
teh greenhouse gas implementation partnership whilst also developing a cross-departmental "green growth"
61
lec 3: ecosystems
organisms within their abiotic environment
identifiable area/space
producers (green plants, algae, photosynthesis)
consumers (herbivores, carnivores, parasites)
decomposers (soil fauna, fungi, bacteria)
62
lec 3: ecosystems
photosynthesis
6co2 + 12H2O + light energy --> C6H12O6 + 6H20 + 6O2
63
lec 3: ecosystems
respiration
C6H12O6 + 6O2 --> 6H20 + 6CO2
degraded energy rich compounds
consumes O2, produces CO2
running day + night
most organisms respire
64
lec 3: ecosystems
productivity
GPP
gross primary productivity
= C fixed in plant photosynthesis
65
lec 3: ecosystems
productivity
NPP (primary)
net primary productivity
= GPP - plants respiration
66
lec 3: ecosystems
productivity
NPP (ecosystem)
net ecosystem productivity
= NPP - heterotroph repsiration (animals, decomposers)
67
lec 3: ecosystems
effect of CO2 in C3 plants
examples
rice, wheat, soybeans, and most trees
68
lec 3: ecosystems
effect of CO2 in C3 plants
short term
stimulates photosynthesis
results in enhanced photosynthesis, increased carb synthesis + accumulation of starch and sugars in short term
69
lec 3: ecosystems
effect of CO2 in C3 plants
long term
however high CO2 can cause a decline in photosynthesis rate in long term
particularly if nutrients (nitrogen) are in short supply
70
lec 3: ecosystems
effect of CO2 in C3 plants
feedback system
the accumulation of carboydrates in leaves can repress the expression of genes encoding photosynthetic proteins
this feedback system is important because it helps restore the carbon
- nitrogen imbalance
71
lec 3: ecosystems
effect of CO2 in C3 plants
- nitrogen limitations
under co2 enrichment rate of N uptake from soil increases
- cannot keep up with photosynthesis rate
thus there will be a progressive nitrogen deficit (particulary in leaves)
higher tissue carbon/nitrogen ratios also impact soil + litter quality (which tends to decline under CO2 enrichment)
(microorganisms work in different ways)
72
lec 3: ecosystems
effect of CO2 in C3 plants
FACE EXPERIMENTS
(medek 2017)
eco2 reduces overall protein conc (6-14%) in key crops (rice wheat barley)
18 countries could lose more than 5% protein intake
additional 150 mil people at risk of protein deficiency by 2050 due to eco2 (further analysis required)
73
lec 3: ecosystems
ecosystem - carbon
carbon sequestration
net flux of carbon out of atmosphere (+into another reservoir)
up to 40% of C made via photosynthesis given to microorganisms and sequestered in soil
74
lec 3: ecosystems
ecosystem - carbon
eddy flux towers
direct measurement of forest atmosphere changes
continuous recording of net CO2 exchange evaporation, and energy flux
tree and leaf level
75
lec 3: ecosystems
forestry economics
- commerical timber products
--> recreation
not just concerned with the production of timber it also includes environmental amenities that forests provide
76
lec 3: ecosystems
forestry economics
important resource
habitat and ecosystem services
source of Co2
natural carbon sink
77
lec 3: ecosystems
forestry economics
- commercial timber products
--> renewable resource
central issue if forestry economics is the determination of the best time to harvest timber ( and what extent timber production should be emphasised)
the multiple outputs,+ve and -ve from forestry externalities make it distinctive from other renewable resources
Many of these externalities involve environmental services and amenities that are principally non-market (further complicating management)
78
lec 3: ecosystems
Forests managed for timber value
from a timber value viewpoint forest harvesting should coincide with the max. present value of profits
trees grow over time, as a result so does their timber value
the value of trees if set against their opportunity cost
- i.e. the return that the money tied up in trees could earn
this is given by the marginal growth value (MGV) divided by the value of trees
79
lec 3: ecosystems
forests managed for timber and non-timber value
if the forest has a non-timber value (recreation) this changes teh socially optimal forest rotation
instead of maximising teh present value of the timber the forest is managed so as to maxmise the present value of timber and non-timber values
v(G) continuously increases
the optimal rotation is where the rate of return of teh total value (MVG+G) is equal to the rate of interest
80
lec 3: ecosystems
forests managed for timber and non-timber value
likely to cut down trees
when have other options less likely to cut down trees
where there are non-timber values the rotation length will be longer
it may even be optimal for some forests with relatively large non-timber values to never harvest the timber
--> trees can grown for longer, sequester more carbon
81
lec 3: ecosystems
forest ecomonics
GRAPH
82
lec 3: ecosystems
BIFoR (Norby)
trees grown under eco2 ave higher photosynthesis and better growth
83
lec 3: ecosystems
BIFoR (Norby)
stats
fine roots
40% increase
84
lec 3: ecosystems
BIFoR (Norby)
stats
root carbon exudation
39% increase
85
lec 3: ecosystems
BIFoR (Norby)
stats
root Nitrogen uptake
36% increase
86
lec 3: ecosystems
BIFoR (Norby)
stats
N supply
20% faster
87
lec 3: ecosystems
BIFoR (Norby)
stats
co2 uptake
23% increase
88
lec 3: ecosystems
BIFoR (Norby)
stats
leaf mass
increase
89
lec 3: ecosystems
BIFoR (Norby)
stats
tree trunk growth
28%
90
lec 3: ecosystems
BIFoR (Norby)
stats
litterfall
9.5% increase
91
lec 3: ecosystems
free-air CO2 enrichment (FACE)
FACE facilities developed across world to grow plants in the field with controlled high co2 levels under fully open air conditions
e.g. 2001-2007 campaign IL
built within natural field, farmers, made up of pipes that supply co2
92
lec 3: ecosystems
free-air CO2 enrichment (FACE)
soyFACE
in the soyFACE study 16 plots were set up for co2 or ozone fumigation, plus drougt or temp treatments without damage to emerging soybean crop
93
lec 3: ecosystems
free-air CO2 enrichment (FACE)
studies have shown that crop plants..
grow better under eco2
across 186 independent studies of 18 C13 crops increasing CO2 by ca. 200ppm caused a ca. 18% increase in yield under non-stress conditions
legumes and root crops showed a greater increase in yield than cereals
94
lec 3: ecosystems
free-air CO2 enrichment (FACE)
conclusions
nitrogen deficiency...
reduced average yield to 10% as did warming by 2C
95
lec 3: ecosystems
free-air CO2 enrichment (FACE)
conclusions
C4 crops were...
not more productive under eco2
expcept under drought
96
lec 3: ecosystems
free-air CO2 enrichment (FACE)
conclusions
the yield response of C3 crops were...
diminished by N deficiency and by wet conditions
97
lec 3: ecosystems
free-air CO2 enrichment (FACE)
conclusions
strong correlation of...
yield response under eco2 to genetic yield potential in rice and soybean
98
lec 3: ecosystems
conclusions
most plants generally grow better under...
eco2
there is a strong fertalisation effect
but there can be problems caused by limitations of other nutrients (nitrogen)
99
lec 3: ecosystems
conclusions
nature based solutions to climate change require that...
forests and grassland assimilate the extra co2 and store it in soils
however plants (seeds) may become nutrient poor (poor soils)
tropical forests are experiencing unprecedented high temps conditions due to climate change that could limit photosynthesis
100
lec 3: ecosystems
conclusions
the trees in the hottest amazonian forests
are already sensitive
experiencing temps close to thresholds of high-temp sensitivity
need to monitor carefully
tipping point
e.g. Nova Xavantina, Brazil
101
lec 4: climate change and water cycle
vapour pressure and vapour pressure deficit
atmosphere demands vapour
e.g. N africa
atmosphere able to hold more water but is not getting any water
therefore dryer
102
lec 4: climate change and water cycle
oceans
less average evaporation from oceans
(Yuan 2019)
103
lec 4: climate change and water cycle
precipitation
more runoff into oceans (before can infiltrate soil)
floods (guardian 2022) - climate change making worse
less snow (more water per event) (washington state university 1959)
104
lec 4: climate change and water cycle
evapotranspiration
less water in natural reservoirs
more evaporative demand
(Vano 2020)
105
lec 4: climate change and water cycle
drought
levels of drought increase
e.g. every 2 years instead of 10
not enough time to recover
time is an important factor
reservoir supply drinking water in uruguay almost depleted (guardian 2023)
106
lec 4: climate change and water cycle
too hot and humid for humans
some areas have already experienced conditions at or near human survivability limit of 35 C
(NOAA based on Horton)
107
lec 4: climate change and water cycle
too hot and dry for plants
yuan 2019
40 years ago became obvious in last few years seen larger effect of climate change
seeing what we know could happen
not catastrophic everywhere, but in some places no longer viable
108
lec 4: climate change and water cycle
food security
different plants see different outcomes
109
lec 4: climate change and water cycle
structures of safety
pattern of events changing
have shaped a lot of human activities around water cycle
large impact when water cycle changes
110
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
issues to consider
cost, feasibility , reliability, artifacts, the hypothesis being tested, who will use the information
111
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
question
can co2 enrichment studies today realistically predict life in a high co2 world?
112
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
plant growth chambers
controlled environments
can study physiological impacts
limited on scale (not ideal situation for all experiments)
113
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
greenhouses
larger than growth chambers
allows for more samples
less prone to mechanical failure
a controlled environment (less so than plant chambers)
114
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
open top chambers for field work
allow for natural conditions and can be employed on remote locations
they are limited in size + compromised by chamber effects
e.g. tall grass parire kansas, swiss alpine tundra, australian open top chambers for trees
115
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
FACE rings
have provided the best description for how existing ecosystems respond to step changes in co2 (norby 2005)
23% enhanced growth when increase co2 from 370 to 550ppm
116
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
FACE rings: adv
most realistic way to enrich co2
covers entire communities
minimal edge effects
117
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
FACE rings: dis
cost
limitied no. of replicates and flexbility
low environmental control
118
lec 5: climate warming feedback effects
HOW TO EFFECTS OF ELEVATED CO2
FACE rings: example
Aspen FACE, wisconsin
BIFoR FACE
119
lec 6: feedback effects
biggest impact in...
arctic
sea ice extent decreases (as co2 increases)
smaller - plummets substantially 30-50 yrs ago
120
lec 6: feedback effects
swiss alps
glacial retreat
121
lec 6: feedback effects
spatial and temporal pattern of warming
more important than mean global temp rise
(particularly in terms of extreme events)
122
lec 6: feedback effects
cherry blossom
earlier cherry blossom flowering in kyoto
(Aono 2024)
123
lec 6: feedback effects
temp increase as a result of...
co2 emissions (IPCC)
124
lec 6: feedback effects
threshold effects
certain phenomena will dominate responses if a physiological threshold is exceeded
125
lec 6: feedback effects
threshold effects
- bleached coral
(NOAA)
hot spots - before 2020 only 2 great barrier reef mass bleaching events
2020: 3rd mass bleaching event in 5 years (covered reef n to s)
2024: 5th mass bleaching event in 8 years
repeat bleaching events occurring closer in time (difficult to recover inbetween)
severity of bleaching is increasing
bleaching is quick
126
lec 6: feedback effects
threshold effects
- bleached coral what happens
quick
coral too warm
releases it symbionts, becomes white
possible to recover, but once starved too much will die
127
lec 6: feedback effects
threshold effects
models of coral bleaching
different thresholds for different corals
corals have capacity to acclimate (more resilience to extreme temps)
128
lec 6: feedback effects
threshold effects
models of coral bleaching
coral decline along great barrier reef
since 1995
on crest declined by at least 50%
more resistant in deeper waters
(dietzel 2020)
129
lec 6: feedback effects
threshold effects
models of coral bleaching
- regime change
instead of coral now algae mass
JAMACIA coral cover
- 1976 >75%
- 2020 <2%
130
lec 6: feedback effects
threshold effects
coral restoration
nursery corals not immune to bleaching
Restoration is difficult as it doesn't address the actual problem
need to prevent increase in sea temp
131
lec 6: feedback effects
Implications for food crops
rice leaf temp
above 32 C rice doesn't produce any seeds
heat induces sterility
decreases yield
direct links to co2
- closes stomata
- plants don't have capacity to cool
(Matsui 1997)
132
lec 6: feedback effects
Implications for food crops
night time temps
affect grain yield of wheat and rice
increase in night temp means plants respire more
- this costs energy
- lower the yield curve
(impa SM 2021)
133
lec 6: feedback effects
example
Markagunt Plateu
S Utah USA
lodgepole pine death from bark beetles 2003
increase of tree mortality rate
- sensitive to temp
- mortality rate of all sizes, age, species increases
humidity (dry environment)
pests
(van mantgen 2009)
134
lec 6: feedback effects
sea surface temp and penguin survival
increase sea surface temp decreases penguin chick survival
(le Bohec 2008)
135
lec 6: feedback effects
CLIMATE FEEDBACK
albedo
NASA
melting sea ice decreases albedo
promotes warming
release of carbon
accelerates
136
lec 6: feedback effects
CO2 alters competitive outcomes
oak seedlings
(bradely KL 2007)
oak seedling establishment under increased co2
increase in co2 decreases mortality of seedlings in stressful environments allowing more rapid establishment and shift in dominance
grass --> trees
137
lec 6: feedback effects
CO2 alters competitive outcomes
will C4 plants dominates?
C3 will benefit further (will dominate)
C4 tall grassland --> C3 woodland
- shows interdependence on fire + grazing on potential outcome
(Briggs 2025)
no grazing + fire sustains the C4 grassland
grazing and infrequent fire allows conversion to savanna + woodland
elevated CO2 stimulates tree growth
138
lec 6: feedback effects
co2 fertilisation effect
increase photosynthesis slows increases rate of atmospheric co2
(Donohue, 2013)
139
lec 6: feedback effects
what temp index most relevant?
peak in any year
daily mean
monthly mean
annual mean
140
