APS124 Pheonix 2 Flashcards
On average, as well as getting hotter, the planet is getting…
drier
What are 3 things an organism can do if the climate changes in its environment?
- Move (migrate) - stay in climate envelope via migration (range shift) - most migration so far has occured upslope rather than latitudinally
- Adapt - plastic and evolutionary responses have occurred - plasticity is rapid, but has limts - evolution will struggle to keep pace with rapid climate change
- Die - plenty of evidence that this is happening in response to climate change
Average species (764 species in different taxonomic groups) latitudinal shift is…
- 9km per decade
- greater in regions of greater warming
- shifts generally keep pace with climate, i.e. expected = observed
In the santa rosa mountains, elevation of the dominant plant species rose by … between 1977 to 2006/2007
~65m
Climate velocity is…
the speed you need to move to keep pace with climate change
The global mean climate velocity is..
0.42km yr-1
… regions have low climate velocity
mountainous
Climate velocities are fastest for .. biomes such as…
flat,
deserts, mangroves, flooded grasslands and savannas
High temperature and drought are likely to reduce..
NPP (net primary productivity - carbon gain)
In 2003 (heatwave) there was a … reduction in gross primary productivity across europe, which cancelled out 4 years of net ecosystem carbon …
30%,
sequestration
More evapotranspiration is positively correlated with..
higher annual productivity
(so is precipitation but that also includes factors such as runoff which cause a curved, rather than straight, line correlation)
Forests cover … of the land’s surface
~30%
Populations rely on forest for
- timber
- food
- medicines
- watershed protection
- recreation
- aesthetic value
- spiritual benefit
C sequestration can lead to
negative climate feedback
Trees…
grow slowly but can die quickly
There is increasing tree … in all continents except antarctica, for obvious reasons
mortality
In more drought-adapted forest, mortality is higher during … drought, whereas in less drought-adapted foresr, mortality is higher during … … drought
longer,
short-term seasonal
NDVI is
Normalised Difference Vegetation Index
- leaf cover or greenness or photosynthetic capacity
- used to estimate ecosystem productivity
- 1982 onwards
- Can be used to assess growing season length
NPP is
Net Primary Productivity:
- the net carbon uptake by vegetation
(photosynthesis - respiration)
Satellite data can be used to assess inter-annual variability in productivity, which gives a good idea of..
current sensitivity of ecosystems to climate variation
Seddon et al. (2016) said ecosystem (vegetation productivity requires warmth, water and light, and therefore the key climate change drivers are therefore:
- Air temperature
- Water availability
- Cloud cover
What did Seddon et al. study?
Compared changes in productivity (satellite) with air T, water and cloud data over past 14 years
Vegetation sensitivity index:
How responsive productivity was to inter-annual climate variability
- more sensitive in cooler environments (improved productivity)
- arid systems are very unsensitive
Rubisco is more efficient at…
greater CO2 as there’s less photorespiration
About 23% of photosynthesis is
C4 photosynthesis (with CO2 concentrating mechanism) - so less sensitive to changes in environmental CO2
FACE experiments:
Free Air CO2 Enrichment experiments
- Average crop yield stimulation of 17% (lower than previous estimates)
- Wheat and rice did not respond to elevated CO2
Warming climate also increases rate of..
respiration - more carbon loss
… of the world’s surface is ocean
71%
… of earth’s habitable volume is marine
> 99%
Water is liquid at…
unusually high temperatures and over a wide range of temperatures (0-100C)
Life depends entirely on…
liquid water
Maximum density of water is at … so there is usually…
~4C
liquid water below ice
Sound carries…
very well in water
At 20C, sound travels…
> 4 times faster in water
Approx … salt per 1000g seawater
35g
Salinity is measured in…
practical salinity units (psu), with 35psu very similar to 3.5%
Salt lowers… and increases…
the freezing point of water, its density (so saltier water sinks)
Sea ice extrudes salt, leaving…
saltier water underneath
The sea’s volume and composition has remained…
essentially unchanged for 2bn years
Life originated..
in the oceans
Marine … capture about 3% of the sun’s energy that hits the sea
photoautotrophs
What are the major types of marine photoautotrophs
- Macrophytes “Large marine seaweeds” (e.g. kelp and wrack) - attached to seabed - restricted to shallow coastal areas as need light
- Phytoplankton - overcome coastal dependence by being small (single cells) and floating - occur throughout the oceans (although not homogenously) - produce about half of the oxygen in the atmosphere
What are the 4 main classes of marine phytoplankton?
Cyanobacteria, haptophytes, dinoflagellates, diatoms
- (0.5-300 micron diameter)
- reproduce quickly
- can be incredibly abundant
Phytoplankton tend to sink, and sinking is life-threatening (as less light) - bigger cells sink faster. This is…
the main reason why almost all ocean ‘plants’ are small
However this is a problem because..
nutrients also sink, but light is restricted to surface waters
How is the two-layered ocean dilemma overcome?
Mixing of surface waters by wind, coriolis effects caused by the earth’s rotation, surface currents driven by ocean-atmosphere interactions, all of which drive localised upwelling of nutrient-rich deep waters
Cold water sinks near the poles and moves equatorward through the deep ocean. Tropical water is lifted, mixed, or welled towards the surface. At the surface it is heated and moved towards the poles. This is known as…
thermohaline circulation
How has life adapted to cope with the two-layered ocean?
- Migrations
- phenology (e.g. plankton blooms)
Physical processes result in a …, … ocean. Life has evolved to exploit this
patchy, highly-structured
The top 3 threats to biodiversity are:
- land use change
- climate change
- N deposition
in that order (Sala et al., 2000)
Recent and near future extinction rates have a … greater magnitude than in the fossil record
> 2 order of magnitude
… of the world’s population: water security has a high-level threat
80%
- threat to biodiversity in water systems has almost identical map
65% of continental discharge is classified as…
moderately to highly threatened in terms of biodiversity
Somewhere between … and … of freshwater species have already gone extinct in recent years
10,000-20,000
Global … loss in species richness
14%
- 31% loss in worst hit areas
- human-dominated areas have largest declines
RCP stands for
relative concentration pathway
Multiple … … show increasing species richness - greater increase more recently - closely synchronised with accelerated global warming
mountain summits
The arctic is warming approximately … faster than the global planetary average
50%
- could be 5-7 degrees warmer by 2100
Why do we get greater warming in the arctic?
Polar amplification
- As ice melts, darker land and ocean surfaces absorb more solar energy
- more of extra trapped energy goes directly into warming rather than evaporation (which occurs in areas with more vegetation)
- atmospheric layer that has to warm in order to warm the surface is shallower in the arctic
- As sea ice retreats, solar heat absorbed by the oceans is more easily transferred to the atmosphere
- Alterations in atmospheric and oceanic circulation can increase warming\
+ a lot of these are positive feedback loops
How much of the land in the northern hemisphere is covered in permafrost?
24%
Permafrost stores carbon as…
peat and methane
- ~1300 Gt carbon stored in permafrost (more than twice as much as the atmosphere)
… C in CO2 equivalents could be emitted from thawing permafrost by 2100
350 Pg
Permafrost ground can slump and create..
wetlands which emit lots of methane (due to anaerobic environments
The growing season (snow-free period) in the arctic is now…
2 weeks longer than in the 1970s
- increase in tundra ecosystem productivity and respiration
NDVI in the arctic due to increased vegetation has increased by about … between 1982 and 2015
13%
Arctic sea ice is declining at…
13% per decade
39% chance of…
ice free september minima if global warming is limited to 2C
Ice retreat timing affects:
availability of ice-associated zooplankton and forage fish = resources for seabirds, marine mammals and commercial fish species (e.g. atlantic cod)
Sub-arctic species are expanding…
northwards and are likely to compete with arctic species - some ice-associated bird species are already declining (e.g. ivory gulls)
- extinction of some Arctic endemic species likely if current sea-ice loss continues
Pack ice-breeding seals will experience…
reproductive failure much more frequently (due to late winter/early spring breeding habitat becoming less stable)
Abundance reductions will take place among ice-associated pinniped populations, e.g…
ringed seals, bearded seals, walruses
Models predict polar bears will be eradicated from seasonally ice-covered regions within…
50-70 years (2/3 of world’s polar bears currently live there)
Energy CO2 emissions have doubled since…
1980
Recent growth in energy consumption is dominated by…
developing countries
There is increasing demand for energy to meet…
- social development
- economic development
- improve human welfare and health
(there is increasing need to lower GHG emissions from the energy system, but we must still satisfy the global demand for energy)
What are the main types of renewable energy?
Solar, wind, hydro, bioenergy, geothermal
How much of global energy is produced by fossil fuel?
79.5%
How much of global energy is produced by nuclear power?
2.2%
How much of global energy is produced by modern renewables?
10.4%
What are the fastest-growing sources of RE power capacity?
- Wind power
- Hydropower
- Photovoltaics (solar electricity)
The total global technical potential for renewable energy is…
substantially higher than the global energy demand
Few (if any) energy crops are … … when considering a full life cycle analysis (LCA)
carbon neutral
Land-use change to bioenergy production often means..
destruction of natural ecosystems (e.g. deforestation)
+ competition for land with food production (may mean reduced food security locally, or deforestation elsewhere)
Direct land use change (dLUC) is…
switching from a particular plot of land from some previous use (or disuse) to biofuel crop production
Indirect land use change (iLUC) is…
the impacts of LUC arise elsewhere as an unintended consequence of biofuel crop production
Use of US croplands for biofuels increases … … through emissions from … … …
greenhouse gases, land use change
The Kyoto protocol erroneously treated all bioenergy as…
carbon neutral
- but full LCA needed as doesn’t account for land use change
What is the biggest renewable energy source at the moment?
Hydropower
… of Brazil’s power is generated by hydropower
> 70%
and 2/3 of its hydropotential is untapped (BUT lies in untouched rivers in the Amazon
Belo Monte Dam will be…
3rd largest in world
When reservoirs flood forests…
methane is released (it is estimated that reservoirs contribute 20% of anthropogenic CH4 emissions - likely to be large underestimate)
