climate change

Question 1

what EVIDENCE is there of climate change? (11 pieces)

Answer 1

• ice cores
• pollen analysis
• sea level change
• historical records
• dendrochronology
• retreating glaciers
• weather records
• polar ice melt
• ecosystem changes
• sea- floor sediments
• fossils

Question 2

explain ICE CORES

Answer 2

extraction of ice cores which contain trapped bubbles of gas which represent what the gas composition of the atmosphere was like at that time
can be dated to show how atmosphere has changed overtime- can go back approx. 1 mil years

Question 3

explain POLLEN ANALYSIS

Answer 3

pollen is preserved in sediment- can identify past vegetation types
if pollen is found similar to todays plants, it indicates a similar climate when this pollen was produced

Question 4

explain SEA LEVEL CHANGE

Answer 4

volume of water stored as ice changes overtime indicated temps changes. e.g. raised beaches show past sea levels (emergent so formed by higher sea levels)
can be dated to show when warmer period was (less water stored as ice)

Question 5

examples of HISTORICAL RECORDS

Answer 5

DOOMSDAY BOOK- 11th century- record of what farmers grew
painting of THE FROST FAIR IN LONDON- 17th century

Question 6

explain DENDROCHRONOLOGY

Answer 6

new tree ring every year- thicker ring in warmer+ wetter conditions
can date it to see what climate was like each year (up to 10,000 years ago)

Question 7

explain RETREATING GLACIERS

Answer 7

rocks deposited by glaciers indicate the size it was+ how far it extended. can be dated to show when they were deposited
distant from current glacier shows climate change e.g. is deposited rocks are far away then temperatures have increased within that period of time

Question 8

explain WEATHER RECORDS

Answer 8

details of weather conditions consistently collected since 1861- can show detailed climate change over short period of time they’ve been collected

Question 9

explain POLAR ICE MELT

Answer 9

reduction of ice at both poles- changes in extent of polar ice shows changes in climatic factors effecting them (more melting means increasing temps)

Question 10

explain ECOSYSTEM CHANGES

Answer 10

changes in temp affect availability of food+ shelter- affects what species live in an area
scientists can use changes in how species are distributed to indicate changes in the climate

Question 11

explain SEA FLOOR SEDIMENTS

Answer 11

microfossils called foraminifera accumulate in sea floor sediments- can be used to reconstruct past climates as chemical composition of foraminifera shells indicates ocean temps in which they formed

Question 12

explain FOSSILS

Answer 12

plants+ animals require specific environmental conditions to thrive e.g. coral reefs are sensitive to temperature and water depth
Plant fossils, particularly those of certain species (like palms, cycads, and ferns), can indicate past climate conditions. The distribution of these plants in the fossil record can suggest warmer or cooler climates compared to modern-day locations.
For example, finding fossilized palm trees suggests a warmer, tropical climate.

Question 13

What are 6 NATURAL FORCINGS of CLIMATE CHANGE?

Answer 13

• milankovich cycles- eccentricity, precession, obliquity
• volcanic eruptions
• meteor impacts
• solar output
• plate tectonics
• natural atmospheric greenhouse gases (CO2)

Question 14

Which NATURAL FORCINGS of CLINATE CHANGE are INTERNAL?

Answer 14

• volcanic eruptions
• meteor impacts
• plate tectonics
• natural atmospheric greenhouse gases

Question 15

Which NATURAL FORCINGS of CLIMATE CHANGE are EXTERNAL?

Answer 15

• Milankovich cycles- eccentricity, precession, obliquity
• solar output/ sun spots

Question 16

Explain ECCENTRICY (stretch)

Answer 16

ORBIT around sun changes from almost perfect circle to ELLIPSE and back again roughly every 96,000 years- changes DISTANCE FROM SUN TO EARTH so AMOUNT OF ENERGY earth relieves changes (at diff times of year)
Currently elliptical orbit

Question 17

Explain OBLIQUITY (tilt)

Answer 17

Earth TILTS ON AXIS as orbits sun (currently 23.5°) - changes between 21.8 and 24.4 over 41,000 year cycle
Changes AMOUNT OF ENERGY that diff lattitudes receives, changing global climate. Greater tilt (24.4°) means areas receiving lots of solar energy e.g. tropics will be larger, whereas generate zones beyond tropics will be smaller.

Question 18

Explain PRECESSION (wobble)

Answer 18

AXIS of Earth WOBBLES on 22,000 year cycle
Earth closest to sun in Jan so winter in northern hemisphere is mild and summer is cool (influences INTENSITY and TIMING of SEASONAL CONTRASTS

Question 19

How do PLATE TECONICS influence CLIMATE CHANGE?

Answer 19

Plate tectonics+ SEA FLOOR SPREADING- distribution of continents has changed
Scale of changes impact climate- LARGE CONTINENTS across HIGH LATTIDUES (poles) INCREASES GLOBAL ALBEDO REFLECTION+ leads to GLOBAL COOLING

Question 20

How do VOLCANIC ERUPTIONS influence CLIMATE CHANGE?

Answer 20

Eruptions please ASH+ SULPHUR DIOXIDE into atmosphe-block out sunlight/ solar radiation (GLOBAL DIMMING) is reflected back into space- short term cooling effect on climate
E.g. Mount Tambora, Indonesia eruption in 1815- decreased global temps by about 0.5°

Question 21

How do SUNSPOTS influence CLIMATE CHANGE?

Answer 21

Sun’s SOLAR OUTPUT of energy VARIES OVERTIME; sunspots are darker areas on sun that increase solar energy output
Increase+ decrease in number on an 11 YEAR CYCLE (variation within cycles)
E.g. period of cooling in late 17th century- THE LITTLE ICE AGE- thoight to have coincided with period where sunspot activity was very low- HISTORICAL RECORDS EVIDENCE- painting of the Frost Fair in London (17th century)

Question 22

How do NATURAL ATMOSPHERIC GREENHOUSE GASES impact CLIMATE CHANGE?

Answer 22

Close relationship between CO2 LEVELS and GLOBAL TEMPS
lower CO2 levels reduces natural greenhouse effect so leads to cooler climatic conditions
E.g. 50 mil years ago- large concentration CO2 in atmosphere (1,000ppm)+ global temps 10° higher
There’s of how CO2 removed relates to plate tectonics- mountains creates, increased rainfall charged with CO2 (OROGRAPHIC RAIN) so removed from atmosphere and transferred to ocean storage.

Question 23

How do METEOR IMPACTS influence CLIMATE CHANGE

Answer 23

Impact of meteor (up to 10 meters)/ asteroid (10m+) from large crater+ can throw up huge amounts of material into atmosphere- can result in large amoutns solar energy blocked out for months or years, changing the climate
E.g. mass extinction of dinosaurs- vlimate change brought on by massive asteroid impact

Question 24

What EVIDENCE is there of RECENT CLIMATE CHANGE (GLOBAL WARMING in the ANTHROPOCENE)
last 100-150 years

Answer 24

• increases in global temperatures
• shrinking valley glaciers and ice sheets
• rising sea level
• decreasing snow cover+ sea ice
• increasing atmospheric water vapour

Question 25

Explain INCREASES IN GLOBAL TEMPS

Answer 25

Consistent rise of global+ land temps in 20th century (esp. last 40 years)- accurate records began in 1880 Steep rise since 21st century- ten warmest years since 1880 have all happened in 21st century

Question 26

Explain SHRINKING GLACIERS AND ICE SHEETS

Answer 26

* In last century, glaciers have retreated everywhere/ even disappeared completely * trends set to continue in Alps, valley glaciers may shrink by 80-96% by end of century * thickness of small glaciers decreased by 12% (avg) since 1961 (equivalent of 9,900km³ of water) * present day melting: approx 1mm increase in sea level each year

Question 27

What is change in the extent of valley glaciers and ice sheets documented by?

Answer 27

* satellite images * ground photographs

Question 28

Which two ice sheets contain 97% of global ice store and are up to 4km thick?

Answer 28

* Antarctica * Greenland

Question 29

What three factors cause the decrease in global volume of ice?

Answer 29

* warming of atmosphere * warming, produces meltwater which penetrates ice+ increases velocity of glacier flow * ocean warming, increasing meeting if ice sheets in coastal areas

Question 30

Explain RISING SEA LEVELS

Answer 30

* began to RISE in MID-NINETEENTH century since 1900 the avg. rise has been 1-2.5mm/year * recent evidence from SATELLITE IMAGERY indicates FASTER RATES (3mm/year) * due to THERMAL EXPANSION+ MELTING of LAND-BASED ICE SHEETS and GLACIERS

Question 31

Explain DECREASING SNOW COVER

Answer 31

* satellite measurements reveal DECREASE in SPRING SNOW COVER of 2% PER DECADE since 1996 in NORTHERN HEMISPHERE * impact on climate: SNOW has HIGH ALBEDO, reflecting 70-80% incoming solar radiation (compared to 10-20% of soil+vegetation surfaces) * diminished snow cover means INCREASED ABSORBTION of solar radiation- sun's energy used to WARM GROUND rather than melt snow, so AIR TEMPS RISE, creates POSITIVE FEEDBACK, which explains the RAPID WARMING currently taking place I'm the Arctic

Question 32

* How high is snows albedo? * Vs soil+ vegetation surfaces?

Answer 32

* 70-80% of incoming solar radiation * 10-20%

Question 33

Explain DECREASING SEA ICE

Answer 33

* sea ice is frozen sea water that FLOATS on the OCEAN SURFACE- found ONLY in POLAR regions *it forms+ melts within the seasons: winter- arctic sea ice covers 17-20 mil km²; summer- shrinks to 4-6 mil km² Since 1778 (when satellite monitoring began), the EXTENT+ VOLUME sea ice in arctic has DECLINED DRAMATICALLY; area sea ice decreased 8% per decade

Question 34

Explain INCREASING ATMOSPHERIC WATER VAPOUR

Answer 34

* water vapour is the most important greenhouse gas- traps huge amounts of energy radiated from the Earth's surface+ creates NATURAL GREENHOUSE EFFECT * AMOUNT WATER VAPOUR in atmosphere is DIRECTLY RELATED to TEMPERATURES+ RATES of EVAPORATION; so in warmer world, there would be more atmospheric moisture * Estimated that every 1° increase in temp caused by enhanced CO2 levels will DOUBLE THE WARMING, due to rising levels of water vapour in the atmosphere * POSITIVE FEEDBACK- large concentration water vapour will ENHANCE GREENHOUSE EFFECT, causing MORE EVAPORATION, leading to MORE ATMOSPHERIC VAPOUR, more evaporation, more warming and so on

Question 35

what is ALBEDO and how is this changing?

Answer 35

reflection of solar radiation ice is white so reflects the solar radiation/ input; oceans are darker so absorb more+ reflect less change overtime: shrinking+ melting glaciers so increase volume of water stored as liquid in oceans, so less reflective ice surface (decreased glaciers means decreased albedo reflection)

Question 36

what are the 3 GREENHOUSE GASES? how long have they been rapidly increasing for?

Answer 36

* water vapour * carbon dioxide (CO2) * methane (CH4) 200 years (due to human activity)

Question 37

how has the CONCENTRATION of CO2 CHANGED OVERTIME?

Answer 37

CO2 accounts for more than 3/4 GHG emissions before 1800: conc. in atmosphere was 280ppm; 2015: hit 400ppm for first time (more than 40% increase in 200 years) increase of atmospheric CO2 is accelerating (NEARLY HALF OF INCREASE SINCE 1960)

Question 38

how has the CONCENTRATION of METHANE (CH4) CHANGED OVERTIME?

Answer 38

1984 (when direct measurements began): 1735ppb; 2009: 1890ppb this is a SLOWER RATE of increase than CO2, but CH4 is a more potent GHG which 25 times the GLOBAL WARMING POTENTIAL CH4 represents 15% of all GHG emissions

Question 39

what is the chemical formula of METHANE?

Answer 39

CH4

Question 40

why is METHANE measured in PPB?

Answer 40

smaller conc. than CO2 in atmosphere

Question 41

main 3 reasons for RISING GHG EMISSIONS since PRE-INDUSTRIAL EREA?

Answer 41

* increased demand for energy- due to INDUSTRIALISATION, TECHNOLOGICAL ADVANCES, (manufacturing+ transport) * huge GLOBAL POPULATION GROWTH- (1bil in 1800- 8.4bil currently) + rising STANDARDS OF LIVING (e.g. electricity in every home) * change in LAND-USE, esp. DEFORESTATION (forests are carbon sinks)+ DRAINING OF WETLANDS for food production+ urban development

Question 42

how has the INDUSTRIAL REVOLUTION impacted GHG emissions? when did it ocur?

Answer 42

* 19th century * since this the world relies heavily on ENERGY from FOSSIL FUELS- dependence still remains despite development of NUCLEAR POWER+ RENEWABLES. * large proportion of global anthropogenic emissions (2 thirds) comes from fossil fuels (by ENERGY+ MANUFACTURING INDUSTRIES+ TRANSPORT)- release 10 BILLION TONNES ANUALLY * since 1750: cumulative anthropogenic emissions total 2000 GIGATONNES which is 3/4 of emissions

Question 43

how have emissions changed since the MID-20TH CENTURY?

Answer 43

demand for fossil fuels increase in scale+ intensity coal production reached record levels in early 20th century two of WORLD'S LARGEST ECONOMIES (CHINA+ INDIA- over 1.3bill population each) powered largely by COAL COAL is DIRTIEST FOSSIL FUEL- 2 times emissions of CO2 than NATURAL GASES+ 20% more than OIL EXPANSION of WORLD ECONOMY (1990-2012) (stimulated by GLOBALISATION+ growth of EDC'S like China) INCREASED CONSUMPTION of FOSSIL FUELS (51% increase in CO2 emissions- International Energy Agency)

Question 44

how has CHANGE in LAND-USE impacted emissions?

Answer 44

1 third emissions from land-use changes+ emissions of carbon from DEFORESTATION, DRAINED WETLANDS, CULTIVATED SOILS. these processes TRANSFER CARBON from BIOSPHERE to ATMOSPHERE 40% land surface used for agriculture; vs 7% in 1700 global loss of forest cover since 1700: 15-25% lost today forests clothe 31% of land deforestation (mostly tropics+ sub tropics) continues apace with 5.2mil ha cleared between 2000-2010