Climate Science Flashcards
1
Q
what is a time series?
A
A time series is a sequence of data points or observations collected or recorded at specific time intervals, typically at equally spaced time points.
2
Q
what is an anomaly?
A
An anomaly is a departure of a climate variable (e.g., temperature) from a reference value, usually a long-term average over a defined reference period
3
Q
name 2 common ways in which se surface temperature (SST) has been measured
and which method led to warmer readings?
A
- engine intake water
- buckets
engine intake water was a tenth of degree warmer on average
4
Q
why is the northern hemisphere warmer?
A
because it has more land, which has a much lower specific heat capacity than water
5
Q
The World Meteorological Organization (WMO) defines climate as:
A
the 30-year average weather
BUT: the length of averaging to be confident in a long-term change depends on the variability
6
Q
on a timeseries, what is a hiatus and a surge?
A
- Hiatus refers to a period within a time series where there is a temporary interruption or pause in the expected or typical trend or pattern.
- A surge in a time series refers to a sudden and significant increase or spike in the data values over a relatively short period.
7
Q
why is the troposphere warming and the stratosphere cooling?
A
Troposphere gets warmer because it absorbs the heat from the earth (with the CO2 it contains), this means less heat will reach the stratosphere
Much like when you put a blanket on, you will get warmer but your room will cool down because you are no longer heating it
8
Q
How do we understand the climate before we had instrumental measurements? provide examples
A
- Climate proxies
- A climate proxy is a measurable physical or biological indicator that provides information about past climate conditions.
- e.g. tree rings, ice cores, coral, pollen, fossils, sediment cores
9
Q
what was the medieval warm period?
A
The Medieval Warm Period, also known as the Medieval Climate Anomaly, occurred roughly from around the 9th century to the 14th century (approximately 950 to 1250 AD).
During this period, parts of the Northern Hemisphere experienced relatively warmer temperatures compared to the preceding and succeeding centuries.
10
Q
what was the ‘little ice age’?
A
The Little Ice Age was a cooler climatic period that occurred from roughly the 14th century to the 19th century (approximately 1300 to 1850 AD).
The LIA was characterized by colder temperatures, especially in the Northern Hemisphere, with periods of more frequent and severe cold spells, harsh winters, and glacial advances.
11
Q
what are the 2 kinds of ‘natural variability’?
A
- “Internal” variability
Behaviour of Earth’s chaotic system
No long-term trend - Naturally “forced”
Changes in the sun (now getting dimmer), Earth’s orbit (shifts), volcanoes
Can cause long-term trend
12
Q
advantages and disadvantages of climate proxies
A
Advantages:
Very long record (potentially millions of years)
Disadvantages:
Often respond to several climate variables in a complex way
May have low resolution (space & time)
Must be preserved (record may be biased or ‘overprinted’)
13
Q
what were the reconstruction methods for these periods?
- 1979 onwards
- 1850s - present
- 1kyear
- 5 kyear
- 200 kyear
- 800 kyear
- 2Myears
A
- 1979 onwards = satellite measurements of global temperatures
- 1850s - present = surface thermometers in widespread use
upper air measurements since 1950s - 1kyear = written records
- 5 kyear = tree rings – most trees considerably younger!
-Coral - 200 kyear = ice cores, lake sediments, cave deposits, ice-rafted debris
- 800 kyear = ocean sediment cores
- 2Myears = Quaternary sediments, pollen, etc.
14
Q
what do tree rings tell us?
A
Broadly: wide ring = warm days and sufficient water; narrow ring = stressful conditions (e.g., water shortage)
In detail: a mixture of conditions is recorded
depends on what a given tree requires for growth, and what is limiting
More sensitive to summer than winter temperature
Many properties of a ring can be measured
width, density of early wood, density and width of wood grown late in the season
isotope chemistry of the wood composition of the rainfall, rate of photosynthesis, etc.
15
Q
in the 1960s what happens to tree ring data?
A
For reasons that are not yet understood, temperatures derived from tree rings started to diverge from measured temperatures
16
Q
what is the CET? and when did it begin?
A
Central England Temperature (CET) from 1659 CE until present, so the longest climate record available in the world
17
Q
what were some characteristics of the medieval climate anomaly?
A
- Limits of cultivation were higher on hills than in later centuries
- Vineyards in the UK
The upper tree line was higher than earlier or later times - Several periods of prolonged drought
-very narrow tree rings
-evidence suggesting a predominance of “anticyclonic” weather over Northern Europe
18
Q
is sea level a reliable climate indicator?
A
Yes, it has a good correlation with reconstructed temperatures and is well recorded geologically
19
Q
was the latest decade warmer than any multi-century period after the last interglacial, around 125,000 years ago?
A
yes
20
Q
climate myth!:
Scientists in the 1970s predicted an ice age
A
This isn’t exactly a myth – it was a published result from prominent climate scientists, but the research was taken far out of context in media articles, and the consensus amongst scientists was that greenhouse warming was the bigger problem
(because of aerosols, which were delt with in the 80s, potentially preventing this ice age)
21
Q
how does the mid-pliocene’s (3-3.3 million years ago) climate compare with today’s?
A
it had similar levels of CO2 (360-400ppm) but was much warmer (3.2 degrees warmer) and had a higher sea level (5-25m), scientists unsure why
22
Q
how does the cenozoic era’s (last 66M years) climate compare with todays’s?
A
CO2 up to >5 times present day (7 times pre-industrial)
Reduced through silicate weathering etc.
Global temp. up to 8-10 °C higher than today during ‘Greenhouse’ times
Overall descent into ‘icehouse’
23
Q
how do the stats of the mid-pliocene (3.3-3M years ago) compare to today’s?
A
- Atmospheric CO2 estimated to be 360-400 ppm (now 402-420ppm)
- Continental configurations were similar to present
- Many plant and animal species also exist today
- Orbital configuration similar to present (global mean insolation = –0.022 W m–2 relative to present)
- Global mean air temperature 3.2 °C warmer
- Sea level 5-25 m higher
High latitude ocean SSTs were 7 °C higher than 1850-1900 - Tree line 2000 km further north in Canadian Arctic
- High latitude air temperatures 10-20 °C higher
24
Q
when did the current ice age begin?
A
The current ice age, known as the Quaternary glaciation, began approximately 2.58 million years ago during the Pleistocene epoch
25
Reconstructing temperature using ice cores (why it works)
- Known fraction of H218O to H216O in evaporated water (about 0.19%)
- Greater fraction of H218O condenses than H216O
- Lots of H218O in precipitation
- Air moves north and gets colder
- Strong depletion of H218O in precipitation relative to H216O
26
what is a power spectrum?
A power spectrum is a mathematical tool used in signal processing, physics, astronomy, and other fields to analyze the frequency content of a signal or time series. **It represents the distribution of power (or energy) across different frequencies** within the signal.
27
what did serbian mathematician Milutin Milankovic propose in 1920?
that variations in Earth’s orbit would influence climate
28
watch this video on orbital variations and make some flashcards on it
https://www.youtube.com/watch?v=ZD8THEz18gc
29
Earth's axis of rotation is tilted relative to the orbital plane
Currently the tilt (obliquity) is .....
Tilt varies between about ..... and ..... with a period of around ......
- 23.5°
- 22.1°
- 24.5°
- 41 ka
30
large obliquity leads to....
more exaggerated seasons
31
When the axis points toward the Sun in perihelion (i.e. the north pole is pointed towards the Sun)......
the northern hemisphere has a greater difference between the seasons while the southern hemisphere has milder seasons.
32
The period of precession of the Earth's orbit is complicated by other planets (mainly Jupiter); (how long is the period)
it is between 19 and 21 ka (but really 26Ka)
33
The orbit affects the latitudinal distribution of solar radiation
jj
34
what are Dansgaard-Oeschger oscillations
Dansgaard-Oeschger (D-O) oscillations are **rapid climate fluctuations** that occurred during the **last glacial period**, approximately **every 1,500 years**. These events are characterized by abrupt warming (**5-8°C**) followed by **gradual cooling **and have been primarily identified in Greenland ice core records.
(they don't occur during interglacials)
35
Abrupt climate changes during deglaciation:
- Solar insolation of the NH increased
- Ice sheets receded
- CO2 rose to present-day levels
- Temperature rose sharply 5oC
36
what was the Bølling-Warming event?
- it happened about 15k years ago
- 4-5 °C N. Hemisphere warming in few decades
- Change in meltwater routing → disrupted North Atlantic ocean circulation
→ reduced poleward heat transport
37
climate myth:! Global temperatures were higher in the early Holocene (8000-10000 years ago) and it was even called the “climate optimum”, which again shows that there’s nothing unusual about today’s climate change
Indeed, it almost certainly was warm in that period, but today’s global mean temperatures now exceed those in the early Holocene. Nevertheless, climate reconstructions remain uncertain, so there still a lot to be learned about natural climate variability
38
Climate of the Holocene (last 12 kyr):
- Relatively stable climate in the Holocene
- Early Holocene warmer than late Holocene, but still an open question
- Cooling trend is not understood
-- Climate models don’t reproduce it
39
what is meant by 'energy balance'?
Energy balance means that the energy absorbed by an object is equal to the energy it gives out (emits)
Energy balance determines the temperature of an object
e.g. Energy absorbed from the sun must equal energy emitted by Earth to space
40
what does incoming solar radiation consist of?
Shortwave:
- UV
- visible light
- near-infared
41
what does outgoing terrestrial radiation consist of?
- longwave/ infared radiation
-this is what is absorbed by greenhouse gases
42
Earth receives energy from the sun (solar radiation) at a rate of...
Averaged over all latitudes, this is...
...1368 W/m2 (Watts per square metre)
averaged over all latitudes this is 1/4×1368 W/m2 = 342 W/m2
43
Earth’s atmosphere has a heat capacity of...
700 J/kg/K
44
Earth’s atmosphere weighs about...
3.5x10^18 kg
45
Earth has a surface area of...
5x10^14 m^2
46
what is the formula for 'energy emitted'
E = sT^4
where - E = radiative energy flux (W/m2)
- T = absolute temperature (K = oC+273.15)
- s (sigma) = **Stefan-Boltzmann** constant (**5.67x10-8** W/m2/K4)
47
A fraction of incoming solar radiation is reflected back to space and plays no role in the energy balance of the planet. This fraction is called the
planetary albedo
Earth’s global average albedo = 0.3
therefore 30% of incoming solar radiation is reflected
48
Ratio of actually emitted radiation to maximum possible is the...
emissivity, e (epsilon)
49
The solar flux at 50 °N is ......... of its value at the equator
cosine(50°)
50
what is earths emissivity measured from space?
~0.61
51
The natural greenhouse effect is the temperature difference between...
- what causes this difference?
- how much does this effect increase global average temperature?
the temperature difference between Earth with an atmosphere and Earth without an atmosphere
- Difference is caused by absorption of outgoing infrared radiation by greenhouse gases
- 33 degrees celsius
52
explain the 'enhanced' greenhouse effect
- When a greenhouse gas is added to the atmosphere, the amount of outgoing LW radiation initially decreases
- Earth is transiently not in energy balance
- Earth warms up and radiates at a higher temperature (E = esT4)
- Increased radiative energy loss brings Earth back into energy balance (but at a higher temperature)
- This is the most fundamental climate feedback, known as the Planck Feedback
53
Radiative forcing
**is the change in the radiation1 balance at the top of the atmosphere that results from a change in the climate system2, assuming that all other components of the system are unaffected
It is defined in such a way that positive forcing corresponds to heating (more incoming than outgoing radiation)
1Radiation includes shortwave and longwave
2Such as changes in CO2 concentration, land surface, cloud cover, solar radiation, etc.
54
Advantages and Disadvantages of Radiative Forcing
ADVANTAGES
Convenient, first order measure of the instantaneous relative climatic importance of different agents
Computationally efficient (you don’t need a complete climate model)
DISADVANTAGES
The climate response (i.e., temperature change) varies between different forcing agents (later lecture)
It doesn’t tell us how long the forcing lasts after we emit a gas
55
global warming potential (GWP) is....
the predicted radiative forcing of a gas on a given time horizon - say, 20, 100 or 500 years from now. GWP accounts for:
**The radiative forcing for a known amount of a gas in the atmosphere** (W/m2)
**The lifetime of the gas in the atmosphere**
The indirect effects of the gas on radiative forcing
56
about _____ of current CH4 emissions are anthropogenic
__% contribution to radiative forcing
present concentration has not been exceeded in past _________ years
about **HALF** of current CH4 emissions are anthropogenic
**20**% contribution to radiative forcing
present concentration has not been exceeded in past **650,000** years
57
CO2 vs CH4 vs N2O vs halocarbons
- lifetime
- GWP (20 years)
- GWP (100)
CO2
- variable (>100 years)
- 1
- 1
CH4
- 12 years
- 62
- 23
N2O
- 114 years
- 275
- 296
halocarbons
- 11.9 - 260 years
- up to 10000
- in the ppt's
58
How is methanes lifetime affected by its emission rate?
Increased CH4 = reduced OH concentration
Reduced OH concentration = increased CH4 lifetime
59
sources of nitrous oxide..
- Increased fertiliser use (overdosing fields with ammonia)
- Nylon production
- Nitric acid production
- Vehicular emissions
60
the Montreal Protocol on Substances that Deplete the Ozone Layer banned what?
CFCs
61
Tropospheric ozone (O3) is a _________produced by _________ reactions involving hydrocarbons and nitrogen oxides typical of biomass burning and urban pollution
About _______ of total ozone is in the troposphere
Ozone is short lived (____)
Not retrievable from ice cores
Long-term monitoring with high spatial resolution needed to detect trends
Tropospheric ozone (O3) is a **POLLUTANT** produced by **PHOTOCHEMICAL** reactions involving hydrocarbons and nitrogen oxides typical of biomass burning and urban pollution
About **ONE-SIXTH** of total ozone is in the troposphere
Ozone is short lived (**DAYS**)
Not retrievable from ice cores
Long-term monitoring with high spatial resolution needed to detect trends
62
Aerosol particles are a mixture of:
sulfates,
nitrates,
organic compounds, ammonium,
metals, dust, sea salt...
63
what are aerosols
An aerosol is a **suspension of fine solid particles or liquid droplets in a gas**. In the context of atmospheric science, aerosols refer to **tiny particles or droplets suspended in the Earth's atmosphere**.
64
How do aerosols modify clouds?
Aerosols modify clouds through several mechanisms, including:
- Serving as **Cloud Condensation Nuclei** (CCN) for cloud droplet formation.
- Influencing cloud microphysics, such as **droplet size** and **distribution**.
- Impacting cloud **lifetime** by affecting dynamics and stability.
- Influencing **precipitation** formation processes within clouds.
this can **increase** cloud reflectivity (**albedo**), decreasing radiative forcing
65
Aerosol sources:
Natural:
- sea salt
- DMS
- Dust
Anthropogenic
- Sulfur dioxide (forms sulfate aerosol)
- organic carbon (from fossil fuels and fires)
66
3 main sources of sulfur dioxide in our atmosphere
- burning fossil fuels (dominate by about a factor of 6)
- volcanoes
- phytoplankton DMS (Dimethylsulfide)
67
what is a climate model?
- A computer program (written in Fortran language) that simulates the three-dimensional time-evolution of the atmosphere, oceans and land surface
- The computer program integrates the equations of fluid flow, radiation, clouds etc to calculate the time-and space-dependent evolution of the climate system
- Simulating 100 years typically takes weeks on a supercomputer
68
what is discretisation?
- **Splitting continuous quantities into discrete units or ‘cells’ on a grid**
- Necessary because the computer can carry information only at a finite number of points
- Implies averaging of quantities at the sub-grid scale
Examples
- Spatial (lat, lon, altitude grid cells)
- Aerosol and cloud particles (particle size classes)
- Radiation (wavelength bands)
69
what is parameterisation?
- **Parameterisation is the simplification of processes – simpler equations that capture the essence of the process at much lower computational cost**
- Parameters often tuned to make the simpler model behave realistically
- Almost all processes are parameterised in climate models
- Model complexity is not the problem. The problem is poor parameterization, which is limited by computational cost
70
what is The Coupled Model Intercomparison Project
(https://pcmdi.llnl.gov/CMIP6/) run by World Climate Research Program
The global research community’s way of ‘pooling’ knowledge from more than 40 models
71
define 'detection'
Demonstrating that an observed change is significantly different from that which can be explained by natural internal climate variability
72
define 'attribution'
The isolation of cause and effect
73
how is attribution done?
By comparing the temporal and spatial patterns of climate change in models to the real-world patterns
- only feasible if the spatial and temporal patterns have unique characteristics
74
what are 'emission scenarios'?
Emission rates (e.g., kilogram per square metre per day) of greenhouse gases and aerosols on a global 2-D grid (i.e., map) through time
Usually natural emissions are constant (or vary in the model in response to changing wind, T, etc.)
**Scenarios are alternative images of how the future might unfold**
75
The four IPCC AR4 “storylines”
A1
very rapid economic growth
new technologies
population growth to mid 21st century
A2
Continuously increasing population
Fragmented and slower economic growth and technological advancement
B1
Same population as A1
Introduction of clean and efficient technologies
global solutions to environmental sustainability
B2
Population similar to A2
local solutions to sustainability
76
what are the 3 'subplots' of the A1 storyline?
A1F1: **Fossil** fuel intensive
A1T: **Technological** advancement leads to development of non-fossil fuel energy sources
A1B: **Balance** across all energy sources
77
what was the aim of the 'paris agreement'?
to keep the increase in global mean temperature to well below 2°C above pre-industrial levels and to pursue efforts to limit the increase to 1.5 °C
78
Limiting warming to 1.5°C implies reaching net zero CO2 emissions globally around....
2050
79
All emission scenarios except ______ lead to increasing CO2 and increasing global temperature
RCP2.6
80
How often does the daily temperature exceed the 90th percentile of the 1960-2018 daily data, in Europe?
The number of such days is increasing at 8 days per decade in Europe
81
what year was the 'warmest summer since 1500 AD'?
2003
Temperatures widely exceeded 40 oC
20,000 to 70,000 excess deaths in Europe
Crop yields down 10-20%, and losses of >10 billion Euro
Approximately 1/3 of excess deaths attributable to air pollution
82
Future projections of cyclones suggest what?
Future projections suggest a net global decrease in occurrence, but an increase in intensity (wind speed and rain rates)
83
what is The Intertropical Convergence Zone (ITCZ)?
The Intertropical Convergence Zone (ITCZ) is a **band of low pressure that encircles the Earth near the equator, where the trade winds from the Northern and Southern Hemispheres converge**. It is characterized by rising air, abundant cloud cover, and frequent precipitation.
84
what shifted the ITCZ south?
caused by aerosol cooling and volcanic eruptions
85
The atmosphere can hold _% more water vapour for every 1oC increase in air temperature
The atmosphere can hold 7% more water vapour for every 1oC increase in air temperature
86
Global precipitation is driven by _________, not air temperature. Locally, precipitation is driven by the amount of ____________ held in the air, which is determined by air temperature.
Global precipitation is driven by EVAPORATION, not air temperature. Locally, precipitation is driven by the amount of WATER VAPOUR held in the air, which is determined by air temperature.
87
how do greenhouse gases affect global precipitation?
Greenhouse gases and some aerosols warm the atmosphere
Warmer atmosphere above an unchanged surface reduces turbulence and therefore reduces evaporation
this effect is cancelled out by the warming surface
88
define 'mitigation'
Climate change mitigation means reducing emissions of greenhouse gases into the atmosphere to prevent warming
89
define 'adaptation'
Climate change adaptation means altering our behaviour, systems, economies, etc. to protect us and the environment from the impacts of climate change
90
what is the goal of mitigation according to UN?
The goal of mitigation according to UN is to “stabilize greenhouse gas levels in a timeframe sufficient to allow ecosystems to adapt naturally to climate change, ensure that food production is not threatened, and to enable economic development to proceed in a sustainable manner”
91
IPCC AR6: To not exceed 1.5 oC above pre-industrial, greenhouse gas emissions need to peak before ____ and decline ____% by ____
2025
43
2030
92
explain the ways in which The role of Agriculture, Forestry and Land Use (AFOLU) has in mitigation
Soils
- No-till farming, conservation farming, regenerative farming (e.g., James Rebanks in the Lake District)
Wetlands
- Peatland restoration/protection (peat stores 43% of all soil carbon, more than all other vegetation)
93
what is geoengineering?
- Deliberate manipulation of Earth’s climate to counteract the effects of rising greenhouse gases
- A climate “risk reduction strategy” or “supplementary option”, not mitigation (IPCC definition)
94
describe Bioenergy with Carbon Capture and Storage (BECCS)
- Max CO2 removal (ppm)
- Relative Cost
Burn biomass as fuel (biofuels), capture the CO2 and pump it into old oil wells
- 50-150
- medium
95
describe Biochar
- Max CO2 removal (ppm)
- Relative Cost
Turn biofuels into charcoal and mix with the soil
- 10-50
- medium
96
describe Enhanced weathering
- Max CO2 removal (ppm)
- Relative Cost
Various ways to enhance CO2 + CaSiO3 → CaCO3 + SiO2 e.g. mixing ground rock with soil
- high
- medium
97
describe Chemical CO2 capture
- Max CO2 removal (ppm)
- Relative Cost
“Artificial trees”: CO2 removed from air by chemical reaction, then disposed of
- unlimited
- High
98
describe Ocean iron fertilisation
- Max CO2 removal (ppm)
- Relative Cost
Adding iron salts to ocean to enhance phytoplankton growth
- 10-30
- low
99
types of solar radiation management:
- cloud seeding
- aerosols in stratosphere
- giant reflectors in orbit (at L1 point)
- desert albedo enhancement (reflectors)
- more reflective crops
- human settlement albedo (white roofs and roads)
100
Alter reflection outside the atmosphere:
__% reflection of the incoming 342 W m-2 is ~_ W m-2
1.2
4
101
define 'climate proxy'
A climate proxy is a recorded quantity from which some aspect of the climate at a particular time in history can be inferred
102
A multi-method reconstruction indicates that the warmest two-century interval was about ___°C warmer than the 1800-1900 period, centering around ____years ago.
- 0.7
-6,500
103
what is the eccentricity period and how long does it last
- (to do with the orbit stretching and pressing)
-96,000 year period
104
what is the obliquity period and bohw long does it last
- (to do with the tilt)
- 41,000 years
105
what is the precession period and how long does it last
-
- 19-21,000 years
106
what are Dansgaard-Oeschger (D-O) oscillations
Dansgaard-Oeschger (D-O) oscillations are rapid climate fluctuations that occurred during the last glacial period. These events are characterized by abrupt warming followed by gradual cooling, and they have been primarily identified in Greenland ice core records.
107
what was the Bølling-Warming event ?
Time Period: The Bølling-Warming event occurred approximately 14,700 to 14,000 years ago, marking the beginning of the end of the Last Glacial Maximum.
Duration: This warming phase lasted for several centuries, indicating a rapid shift in climate conditions over a relatively short geological timeframe.
108
%longwave absorbtion of greenhouse gases (if removed)
water vapour - 39
carbon dioxide - 14
nitrous oxide - 1
methane - 0.7
ozone - 2.7
109
climate sensitivity equation:
change in T = lambda x change in E
change in T = change in global mean temperature
lambda (planck climate sensitivity) = 0.27 K per W/m^2
change in E = global mean radiative forcing
110
what is the climate feedback factor
The climate feedback factor is the ratio of temperature change including feedbacks to the temperature change with only the Planck feedback
111
4 different feedbacks in the climate system:
- ice sheets (reflect radiation)
- water vapour
- planck feedback
- clouds (reflect SW, absorb LW - overall)
112
what is the difference between 'climate sensitivity' and 'equilibrium climate sensitivity' (ECS)?
Climate sensitivity is the temperature change per W/m2 of forcing
Equilibrium climate sensitivity is the temperature change for a doubling of CO2
The Planck ECS is 1.1 K (0.27 K per W/m2 times 4 W/m2)
113
Variability can be separated into:
- Forced changes
- Internal climate variability
114
what are 'forced changes'?
Short lived events like volcanic eruptions
The variability that isn’t caused by external factors
115
what is 'internal climate variability'?
The variability that isn’t caused by external factors
116
what is a 'natural mode'?
- A natural mode is a favoured configuration of atmospheric variability over widely separated points on Earth
- Characterised by simultaneous variations in weather in widely separated regions (several thousand km)
- Often known as teleconnections
- Natural modes tend to recur with periods of years to decades, but are usually irregulatr
117
what are the characteristics of the positive phase of the North Atlantic Oscillation (NAO)?
Strong Pressure Gradient: During the positive phase, the pressure difference between the Icelandic Low and the Azores High is greater than average.
Westerly Winds: Enhanced westerly winds prevail across the North Atlantic, bringing moist and mild air into Europe and the eastern United States.
Storm Tracks: Storms tend to follow a more northerly track, often bringing wet and mild conditions to Northern Europe and dry conditions to Southern Europe and the Mediterranean.
118
what are the characteristics of the negative phase of the North Atlantic Oscillation (NAO)?
Weak Pressure Gradient: In the negative phase, the pressure difference between the Icelandic Low and the Azores High is less than average.
Reduced Westerlies: Weaker westerly winds result in a southward shift of the jet stream and storm tracks.
Storm Tracks: Storms tend to follow a more southerly track, leading to wetter conditions in Southern Europe and the Mediterranean and drier conditions in Northern Europe.
119
Development of our understanding of the carbon cycle
Late 1800s: Svante Arrhenius
Trying to explain ice ages
Infrared measurements of the atmosphere
Human emissions of CO2 would in future be large enough to cause warming
120
Development of our understanding of the carbon cycle
1938-1950s: Guy Stewart Callendar
- Compiled measurements and proposed that 1900s temperature rise could be explained by rising CO2
- Slowly convinced others to take note
121
Development of our understanding of the carbon cycle
1958: Roger Revelle and Hans Suess
- Isotopic ratio of old/new carbon
- About 10% of industrial CO2 is still in the atmosphere
122
Development of our understanding of the carbon cycle
1958: Charles Keeling
- Started first long-term CO2 measurements at Mauna Loa
- First observation on the “planet breathing” and rise from one year to the next
- Now known as the “Keeling curve”
123
Flows of carbon dioxide around the Earth system are called _____, and are usually measured in ______ of carbon (C) per year (not CO2) so that carbon in all its forms (wood, CO2, animals…) can be compared
- fluxes
- Terragrams or Petagrams/Gigatons
124
The exchange of carbon (gigatons of C per year) in all its forms between different storage ‘reservoirs’ (also in gigatons)
Atmosphere -
Vegetation, Soil & Detritus -
Fossil Fuels -
Surface Ocean -
Marine Biota -
Intermediate & Deep ocean -
Surface Sediment -
Atmosphere - 597
Vegetation, Soil & Detritus - 2300
Fossil Fuels - 3700
Surface Ocean - 900
Marine Biota - 3
Intermediate & Deep ocean - 37,100
Surface Sediment - 150
125
how many gigatons of carbon do 'fossil fuels' and 'land use change' add to the atmosphere per year?
- 6.4
- 1.6
126
We have burnt about 244 out of ______GtC (fossil fuels) and atmospheric CO2 has risen by ______Gt, from a pre-industrial value of _____Gt
If we burnt the rest at the same rate, atmospheric CO2 would rise by about a factor of __.
- 3700
- 165
- 597
- 5
