Climate Change Science Defenitions

Recent temperature trends

Land regions warmed faster than oceans in High latitudes of Northern hemisphere

Recent warming of oceans - all latitudes

Seasonal trends in temperature

Greatest warming in spring and winter in N. Hemisphere

Why is Antarctica less affected by temperature change than the Artic

Arctic is an ocean covered by sea ice

Antarctica is an elevated continent covered in more permanent ice and snow

Trends in precipitation

Strong negative correlation between precipitation and surface temperatures

Increases north of 30°

Downward trend in the tropics

Specific heat

air temperature (linked to a detectable temp change)

Latent heat

linked to water vapour (phase change)

Atmospheric circulation changes

Pole ward shift of Atlantic and southern polar jet

Increased and pole ward shift in NH winter storm-track activity

Increased storm activity in the extra-tropical HC

Future changes

Increase in the global mean temperature, Greatest degree of warming at high latitudes

Prediction of global increases in mean precipitation, Increased precipitation at high latitudes - less in the sub tropics

Temporal variation – increases at high latitudes pronounced in winter

IR Adsorption

How much light is absorbed due to gas presence

Ring down

How much light disappears once the light source is removed

Why did we switch to ring down?

It was more accurate

Which wavelength of UV is completely adsorbed by ozone

UV C (100-280nm) the shortest

Atmospheric window

The wavelength range not absorbed by Earth’s atmosphere.

Radiation balance of the earth

Amount of heat absorbed = heat radiation emitted

Radiative forcing (W m^-2)

The influence a given climatic factor has on the amount of downward-directed radiant energy impinging upon Earth’s surface.

Radiative efficiency (W m^–2 ppb^–1)

The capacity of each molecule to absorb long IR radiation

Global warming potential (GWP)

Ratio of the time-integrated radiative forcing from the instantaneous release of 1 kg of a trace substance relative to that of 1 kg of a reference gas (CO₂)

GWP rankings

N₂O = 310 > CH₄ = 21 > CO₂ = 1

GWP Formula

TH is the time horizon over which the calculation is considered

a_x is the radiative efficiency due to a unit increase in atmospheric abundance of the substance (i.e., Wm^-2 kg^-1)

[x(t)] is the time-dependent decay in abundance of the substance following an instantaneous release of it at time t=0.

The denominator contains the corresponding quantities for the reference gas (i.e. CO₂) Which always has a GWP of 1.

Dipole moment

Tension between a positive and negative pole within the molecule

Molecular vibrations

To absorb IR the electric dipole moment of the molecule must change when electrons are displaced

In order to be IR active the stretching of a molecule must be

Asymmetric

v1

stretching

v2

bending motion

v3

asymmetric stretch

What creates the dipole moment

v2 and v3

Electronic transition

Energy level where molecule can partake in reactions due to having adsorbed enough energy

Vibrational transition

Energy level when Bonds in a molecule start to vibrate

Rotational transition

Energy level where molecules start to rotate

Ranking of energy levels

Rotational transition<Vibrational transition<Electronic transition

Formula for GHG lifetime

τ = 1 / k’

k’

[OH] is the pseudo 1^st order rate constant. times concentration of GHG

Why is the formula pseudo first order?

Because we can say [OH] is constant due to its abundance.

Reactions that remove GHGs

CH₄ + OH → CH₃ + H₂O (followed by a chain of reactions in the troposphere)

O₃ + hv → O₂ + O (tropospheric photolysis)

O₃ + OH → HO₂ + O₂ (stratosphere)

N₂O ® N₂ → O (stratospheric photolysis) – major sink for N₂O 

Reactions in the bio(geo)sphere

CO₂, photosynthesis, carbonate formation

CH₄ methane oxidation CH₄ + O₂ → CO₂ and H₂O

Effectors of ERF

Solar and Albedo

Effect solar has on ERF

0.1%

Albedo changers

Change in land use, Black Carbon (soot) on snow causes, Aerosols, Volcanism

Effect of change in land use on albedo

Varies (Deforestation: increase, Urbanisation: decrease)

Effect of black carbon/soot on albedo

Lower reflectance: + 0.06 W/m2

Effect of aerosols on albedo

Can scatter/absorb solar radiation (- 0.45 W/m2) and act as cloud condensation nuclei: more clouds for longer period.

Effect of volcanism on albedo

Add to aerosols in quick high bursts which result in large dips in ERF. Though high levels of CO2 have resulted in a decrease in effect.

Climate (Climate data context)

Temperature (and CO2)

Categories of historical climate data

Instrumental records, The past c. 1000 years, Long-term variability on any timescale over which reliable data can be obtained

Difficulties with instrumental data

Errors, Calibration – the increase over 150 years has only been approx. 0.8 C.

Uniformitarianism

The idea that the Earth was shaped by the same natural processes still in operation today, operating at similar intensities. (Such as how glaciers behave like growing and shrinking)

Representative Concentration Pathways (RCPs)

SSP1-2.6 - Sustainable pathways, SSP2-4.5 - Middle-of-the-road, SSP3-7.0 - Regional rivalry, SSP5-8.5 - Fossil fuel-rich development, Plus SSP1-1.9 - 1.5°C Paris Agreement goal

Eccentricity

The shape of Earth's orbit

Obliquity

The angle that Earth's axis is tilted with respect to Earth's orbital plane

Precession

The direction that Earth's spin axis is pointed

Frequency of Eccentricity change

~100 kyr, with ‘supercycle’ every 413 kyr, nearly circular (low eccentricity e = 0) to slightly oval (high eccentricity e = 0.06)

Frequency of Obliquity

22° to 24.5° every ~ 41 ka.

Frequency of Precession

A cycle of approximately 22,000 years

Implications of greater climate variability on freshwater flow

Increasing in the Arctic,

Earlier spring peak flows (By 1 month)

Increased winter base flows (Northern Hemisphere, snow fed river basins)

Decreased summer flows

Increased climate variability’s effect on lakes

Warming, Increases/decreases in lake levels, Reduction in ice cover (including time), Changes in net water availability, (precipitation – evaporation) determined by changes in river inflows and balance between precipitation and evaporation.

Non-climatic stressors on freshwater systems

Water pollution, damming of rivers, wetland drainage, reduction in stream flow and lowering of the water table.

Fraction of water use taken by irrigation

About 90%

2026 Government Promises about freshwater

£104 billion of private investment

Water Special Measures Act to strengthen accountability

Banned unfair executive bonuses

Made pollution cover-ups a criminal offence

Stress

conditions that are a substantial divergence from optimal and can induce damage or irreversible changes to an organism

ROS

Reactive Oxygen Species

mETC

Mitochondrial electron transport chain

Alternate oxidase pathway

Transfers electrons from ubiquinone directly to oxygen, acts as a safety valve preventing the overreduction of the mETC and generation of ROS

Role of Alternate oxidase pathway in a cell

Involved in retrograde signalling: informing the nucleus of mitochondrial metabolic status, in turn influencing stress related genes

Can plants adapt to changes in temperature

Yes, thermal acclimation (But this is ineffective in extreme changes)

Potential symptoms of heat shock

Tissue damage necrosis, cell death, loss of chlorophyll, drought, water impairment, complete change in metabolism

Limitations of pH optimal

Photorespiration increases at high temperatures which is a ’penalty’

Solubility of CO2 in water decreases at higher temperatures

Membrane lipids (e.g. phospholipids)

Hydrophobic fatty acid chains attached to a polar head group

Impact of temperature on Membrane lipids

Alter their fluidity which can affect the function of membrane-bound proteins and overall cell activity

For each 1°C increase in temperature yields are predicted to decrease

6.0% in maize

3.2% in rice

7.4% in wheat

Temperature behaviour during the day

Extra heat is spread through a thicker layer so air warms slowly (The whole atmosphere is heated)

Temperature behaviour at night

Extra heat is trapped in a thin layer by the ground, so air warms quickly (Only the lower atmosphere is heated)

Plant adaptations to increasing temperatures

Changes in growth, such as becoming taller, Stalks become longer, Leaves shrink, Growth further away from other plants, Plants become unsupported and unstable, Breakages and weakness

Climate change’s effect on poison ivy

Grows faster in warmer, CO2 rich environments

Phenology

The timing of life history events

Temperature effects on plant phenology

Change in flowering periods, longer growing seasons, longer to consumer water

Climate change’s effect on flowering period

Temperature increase = flower earlier in the season, Decrease in precipitation = flower later in the season

Impact of longer growing season

Soil drying and depletion of nutrients

Temperatures where plants show signs of chilling stress

Some temperate plants e.g. apple and potato will show injury at 0-5 C, Tropical/warm climate plants experience chilling injury at 10 - 15 C

Signs of Chilling stress

1.Inhibited metabolism (reduced energy supply)

2. Photosynthesis is impaired

3. Cellular structure - membrane lesions and leakage .

4. Necrosis and cell death

Steps of cellular freezing

1. Supercooling of tissue occurs to around -5 oC. (Though all types of temperatures vary)

2. Ice nucleation takes place in the inter-cellular spaces.

3. Temperatures rise as heat is formed preventing intracellular freezing

4. Cellular contents dehydrate and concentrate - further supercooling

5. Eventually, intracellular contents freeze – usually fatal in non-hardened and non-freezing tolerant plants.

Effect of precipitation on plants

Effect of change is not linear:

dependent on plant age

geography and land relief

soil quality and features

Vapour pressure deficit

Difference between water saturated air and the amount water vapour in the air for a given temperature C.

How much faster is oxygen diffusion in air than water

10,000x

Plant adaptations to flooding

Specialized anatomy (Such as tubes carrying oxygen from the upper plant to the roots), a barrier to radial oxygen loss.

Percentage of anthropogenic CO2 absorbed by plants

~30

Carbon fertilisation effect

Current carbon dioxide levels are sub-saturating (can still increase) for C3 photosynthesis

Limiting factor on photosynthesis increase

Nutrient availability in the soil (Particularly nitrogen)

Complications in photosynthesis process due to climate change

Increase in CO2 = reduction in oxygenation reaction of Rubisco but Increase in temperature = increase in oxygenation

Photorespiration leads to a net loss in fixed carbon = 25% energy loss

Pros of climate change for plants

Increased length of growing season

Increased carbon dioxide = reduced photorespiration

Cons of climate change for plants

Altered pests and diseases

Increased extreme weather events

More droughts and flooding

Plants in agriculture

Agroforestry, biotechnology, crop models, rainwater storage

Benefits of Agroforestry

Increase soil organic C content by 10%, can reduce evaporation of soil water by 41% and transpiration by 32%, increasing the density of trees can help buffer against extreme events, reduced surface run off, increased water penetration and increased water-holding capacity reduces the effects of flooding and droughts

Examples of climate change impacts on terrestrial ecosystems

Increase of invasive species, Reduced population vigour and variability, Many species will not be able to track their favoured climatic condition (Can be direct or indirect such as predators, immobile species such as plants will also struggle), Shift in species ranges (Some species change traits, which may have a positive or negative impacts), Rapidly increasing extinction rates

Biome

Large scale dominant vegetation/functional types

Current climate of UK

Temperate deciduous forest,

Mean annual rainfall ~150-200cm

Mean annual temperature ~10 C

Species establishment

Individuals colonize new areas, where they maintain reproductively viable populations, new habitats may open up because of abiotic and biotic environmental change

Extinction

Eliminates a species from all or part of its geographic range

Dispersal

The movement of individuals away from others of the same species. (Not just limited to climate change)

Resilience / tolerance range

The portion of the abiotic factor's range of variation which a species can survive and function, the level within the tolerance range at which a species or population can function most efficiently is termed the optimum

Methods of adaptation

acclimatisation/ acclimation (individual), species adaptation

acclimatisation/ acclimation

Individuals change their physiology to fit into its environment, (Similar to adapting to seasonal temperature changes) Limited and not passed on to offspring.