Future Environmental Change

Question 1

Outline post industrial climate change

Answer 1

• Global temp rises around 1 1900-2010
• Artic sea ice cover dropping rapidly
• Sea level rise since 19000 – 0.2m
• Hotter and wetter – esp. in higher latitudes

Question 2

Describe sea level change

Answer 2

• Average level of ocean key source of information in global climatic trends
• Redrock rising and sinking
• Ocean basins sinking
• 17cm rise in sea level since 1880
• Caused by land ice melting and ocean warming and expanding

Question 3

Outline changes in surface temp

Answer 3

• Temp warmed by about 0.8 over last century
• Problem of population growth around hot areas – urban heat
• Dramatic rises in temp over last few hundred years

Question 4

Describe the recent warm summers

Answer 4

• Tree ring records to research temp for last 2100
• Summer temp during last 30 years have been high
• No evidence of any period in the last 2000 years being as warm

Question 5

What is El Niño-southern oscillation (ENSO)?

Answer 5

• El Niño accompanies high pressure in western pacific and unusually warm oceans
• La Nina – opposite pattern
• Pattern of el Niño seasons/years

Question 6

What is the North Atlantic Oscillation (NAO)?

Answer 6

The North Atlantic Oscillation is a weather phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level between the Icelandic Low and the Azores High

Question 7

Outline positive NAO phase

Answer 7

• Strengthening of high-pressure cell over Azores
• Weakening of Icelandic low
• Accentuates pressure gradient between cells
• Warmer, wetter conditions in NW Europe and e USA
• Greenland, Canada and Med cooler and drier

Question 8

Outline negative NAO phase

Answer 8

• Gradient between Azores high and Icelandic is reduced
• Situation reversed
• Warmer, wetter conditions in Med, Greenland and Canada

Question 9

What caused the NAO?

Answer 9

• Driven by changes within the atmosphere
• No discernible periodicity
• Displays interdecadal and inter-annual variability
• NAO conditions can persist for many years

Question 10

What is the Atlantic multi decadal oscillation?

Answer 10

• Identified in 1994
• Marked by variations in North Atlantic sea surface temp
• Linked to small changes in N Atlantic branch of thermohaline circulation
• Quasi cycle – 50-90 years
• Linked to variations in air temp and rainfall throughout the Atlantic region

Question 11

What is the pacific decadal oscillation?

Answer 11

• Has spatial distribution similar to ENSO
• Positive phase
• Sea surface temp warmer in tropics
• Cooler in west-central north pacific
• Negative phase
• Can be deconstructed based on SST reconstructions
• Possible cycle 20-30-year cycle – linked to ENSO

Question 12

What are the causes of post-industrial climate change?

Answer 12

• Solar component – changes in sun strength
• Volcanic eruptions – not cause of changes
• Internal variability – random and does not cause great changes
• Anthropogenic component – cause of change in temp

Question 13

What are the potential natural causes of recent warming?

Answer 13

• Great el Niño periods
• Warmer periods expected
• Large volcanic eruptions cool temp – difficult to measure due to sulphur content
• Natural variations have small effect – cannot affect global trend of rising temp
• Cannot be considered responsible for changes

Question 14

What are anthropogenic forcing factors?

Answer 14

• Carbon dioxide - went from 280 ppm to 400ppm
• Methane - half occurrent emissions are anthropogenic
• Nitrogen

Question 15

How can you model the climate?

Answer 15

Models must use natural and humans forcings can reproduce t readings

Question 16

How has the transition from nature to human caused environmental change?

Answer 16

• Balance between difference spheres changing

- Humans more dominate than natural forces

Question 17

What are the three preferred candidate dates for the start of the anthropocene?

Answer 17

1) Early anthropogenic hypothesis at 5020 cal yr BP
2) Boundary at 1610 AD representing the collision of the old and new world, defined by the pronounced dip in atmospheric carbon dioxide
3) Bomb peak at 1664 AD characterised by the peak in atmospheric radiocarbon from annual tree-with atmospheric carbon dioxide from Hawaii, post 1958 and ice core records pre 1958 and global temp anomalies

Question 18

What is the early anthropocene hypothesis?

Answer 18

• Global concentrations of Co2 and methane in ice cores rose from early Holocene
• 80% of anthropogenic GHGs emitted before ad 1750
• Slight warming through the Holocene buffered and natural solar insolation and stopped onset of glaciation

Question 19

What are the cumulative global impacts of the anthropocene?

Answer 19

• Cumulative
• Local and regional impacts caused by human actions – deforestation
• But becoming global problems – land surface reflectance as they aggregate

Question 20

What are the systematic global impacts of the anthropocene?

Answer 20

• Systematic
• Local and regional actions that affect global systems directly, (e.g. carbon emissions at atmosphere) which are now producing local and regional impacts (heatwaves, storminess)

Question 21

How has climate change impacted the hydrosphere?

Answer 21

• Massive changes to both movement and storage of freshwater
• Implications of changing pH in oceanic waters
• How much carbon dioxide it can store?

Question 22

How has climate change impacted the biosphere?

Answer 22

• Years of extensive land use
• Not many wild areas left
• Mega fauna extinctions at the start of the anthropocene
• Populations declined by 40%

Question 23

How has climate changed impacted the lithosphere?

Answer 23

• Human made landscapes - takes material away

- Erosion causes sediment yields and influxes