Climate Change Flashcards
1
Q
What is Climate Change?
A
- Climate change, global warming and climate warming are synonymous terms
- Refer to increases in earth’s mean temperature compared with the ‘normal greenhouse effect’
- Greenhouse effect is warming of earth’s surface by greenhouse gases that allow solar radiation to reach the surface, but impede passage of energy from earth back into space
2
Q
The Greenhouse Effect
A
- Solar radiation (short wavelengths) travels down to earth unimpeded – some reflected back into space by clouds – but much absorbed at earth’s surface, causing the surface and lower atmosphere to warm
- Upward radiation (long wavelengths) emitted from earth’s surface is ‘trapped’ by greenhouse gases, reaching balance between (i) emitted radiation from earth, plus directly reflected solar radiation and (ii) incoming solar radiation, at around 15°C – the ‘natural’ greenhouse effect
- If there was no ‘greenhouse atmosphere’, upward radiation from earth and incoming solar energy would reach a balance at around -18°C
- The natural greenhouse effect is therefore vital for life on earth, but as the concentrations of greenhouse gases (carbon dioxide, methane, water vapour) increase, a new balance is reached at a higher temperature – this is ‘global warming’
3
Q
Patterns of changing global temperatures 1860-2000
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4
Q
CO2 and temperature records from Antarctic ice cores
A
- Ice cores taken 3,600m deep dating back 420,00 years, through 4 glacial cycles
- High correlation between greenhouse gas concentration and temperature
- Notice rapid rise in CO2 at end of time series – the last 150 years – and less evident rise in temperature – likely that oceans acting as a sink
- Consensus that increased greenhouse gases account for about 50% of any temperature change
5
Q
Predicting the Future
A
- World governments have funded scientists to ‘predict the future’ – biological, environmental, economic and sociological
- Biological effects investigated in different systems: cloches, solardomes, ecotron, FACE
- Mainly focused on responses to increases of temperature 1-2°C of above ambient and/or doubling of carbon dioxide concentration from 350 to 700 ppm
6
Q
Cloche system
A
Tiny polythene “greenhouse” that traps heat from the sun and increases ambient temperature withing.
- No control over extent of warming
- Useful in polar regions with no electricity
- May exclude some predators
- Restricted to ‘short’ vegetation and associated fauna
7
Q
Solardomes
A
Larger glass/metal greenhouses. Dome-shaped.
- Greenhouses with control of CO2 and temperature
- Replicate domes
- Can import different soils
- Control over nutrient and water levels – drought
- Used for insect – host plant studies
8
Q
Ecotron
A
- 16 small communities, or microcosms, each housed in separate walk-in chambers with computer-controlled climatic conditions
- Studies on simplified communities of terrestrial plants, animals and microbes as models of the real world
- Bridges the gap between the complexity of real field communities and the simplicity of laboratory or greenhouse experiments
9
Q
FACE system
A
- FACE stands for Free Air CO2 Enrichment
- Realistic simulation of future CO2 concentrations
- No constraints by enclosures
- All other factors are normal: rain, wind, temperature, sunlight, pollination and animal immigration and emigration
- Can be used for long term studies
10
Q
Consequences of climate change
A
- Can manipulate CO2 and temperature in experimental systems: 700 ppm and 1-2°C, BUT cannot predict ‘extreme events’ – another feature of climate change - abnormally high and prolonged temperatures (drought) or very heavy rainfall and flooding
- Major impact on terrestrial and aquatic ecosystems, and sociological/economic effects – flooding in Worcestershire and Gloucestershire in 2007
11
Q
Consequences of climate change: abiotic
A
- Concerns about rises in sea level: 90% of world’s ice in Antarctica, 9% in Greenland and <1% in the rest of the world
- The Antarctic is currently subject to some of the most rapid ‘warming’ anywhere in the world
- Spectacular collapse of the Larsen ice shelf in 2002
12
Q
Glacial retreat
A
- There was a ‘Little Ice Age’ 1550 to 1850 – slightly lower temperatures
- Some glacial retreat 1850 to 1940, some reversal 1940 to 1980, but rapid retreat since 1980 – coincident with higher CO2 emissions – climate warming
- Glacial retreat throughout the world – affects fresh water for irrigation, animal and plants depending on glacial melt, and longer term, sea level
- Cascades range extends from British Columbia (Canada) down to California
- In Washington state, glaciers store as much water as in lakes and reservoirs – and maintain stream flow in summer months
- Between 1984 and 2005, North Cascade glaciers lost an average of more than 12.5 m in thickness and between 20% and 40% of their volume
- About 70% of North Cascades glaciers will disappear if present climate continues
13
Q
Consequences of climate change: biotic
A
- Many emerging ‘bioindicators’ of climate change
- Earlier occurrence of ‘spring’ events: bud burst on trees, appearance of frog spawn
- Can expect ‘northerly’ migration of species as climate becomes more favourable
- But note that animals can move more rapidly than plants – may move without host plants – and unable to establish
- Localised microtopographic effects
14
Q
Consequences of climate change: earlier spring events
A
- Over last century, minimum temperatures have increased more than maximum temperatures – extended the ‘warm’ growing season in mid-high latitudes
- In tundra areas, river ice break-up one week earlier than 100 years ago
- In northern USA, ‘frost-free’ season now starts 11 days earlier than 50 years ago.
- By 2050, many temperate rivers will be ice-free; in colder regions, ice season reduced by a month
- Between 1959 to 1993 plant phenological events advanced by 6 days in spring and delayed by 5 days in autumn
- Ecological implications uncertain: losing synchrony between plants and animals e.g. egg hatch of caterpillars, bud burst on trees, food supply for birds
- Earlier ice break up in Hudson Bay, Canada, reduces seal hunting time for polar bears
15
Q
Consequences of climate change: phenological relationships
A
- Climate changes advances phenology of many species
- Synchrony in phenology disrupted when species in food chain respond differently
- Climate warming has advanced winter moth spring egg hatch more than bud burst on oak – caterpillars starve and reduce food supply for blue tits
- Selection may lead to restoration of synchrony between egg hatch and bud burst
