Unit 4 Topic 2 - Cause and effect of global climate change Flashcards
what natural processes contribute to climate change
- oceanic circulation
-orbital fluctuations in solar radiation (eccentricity, obliquity, precession) - plate tectonic supercycle
- volcanism (only if there’s a lot of eruptions in a short period, it’s not on the syllabus but anton taught it)
how does oceanic circulation contribute to climate change
ocean is carbon sink. Currents absorb/trap cold CO2 rich water below thermocline, cycle disperses heat by moving hot water to poles and cooling it.
what is eccentricity and how does it contribute to climate change
~100k year cycle, other planets’ gravity makes Earth’s orbit more/less elliptical. proximity to sun changes amount of radiation received.
- low eccentricity (circle) = more consistent seasons, hotter climate
what is obliquity and how does it affect climate change
axis tilt varies between 21.5 and 22.1 degrees.
- greater tilt angle = more extreme seasons, favours warm climate and deglaciation.
(at high tilt, poles get blasted during summer). changes are more extreme at high latitudes.
what is precession and how does it affect climate
“wobble” around axis. “makes seasonal differences more extreme in one hemisphere and less extreme in the other”
what is the plate tectonic supercycle and how does it affect climate
500-700 million year cycle.
-position of supercontinents (pangea reference?) effects severity of climate changes
- forming supercontinent=subduction & mountain building causes eroded calcium to trap carbon as limestone in the ocean, cools earth, prevents volcanism so no new CO2 in atmosphere
-landmass at poles means more ice poles
what human activities influence atmospheric composition/climate (4)
-land clearing
-fossil fuel consumption
-gas production (including carbon dioxide, methane, nitrous oxide and
hydrofluorocarbons)
-particulate materials in the atmosphere
what evidence is there for past climactic conditions? (4)
- fossil record (what species were present/dominant)
- pollen grains (same but for plants)
- ice core samples (frozen gas bubbles indicate atmospheric composition)
- isotopic ratios (carbon dating etc)
what are 3 types of climate model? (its complex, check the “climate change modelling” ppt in u4t2 for what each model does)
- nino/nina (interactions of atmosphere and ocean)
- energy balance models - very simple, predict conditions based on proportion of radiation reflected/absorbed
- intermediate complexity - 3d energy balance based on transfer accounting for geographical features (i.e. glaciers)
- general circulation models - very complex, accounts for atmospheric chemistry, carbon cycle etc.
general circulation is mentioned on syllabus but idk what detail you need to know it to.
what is the effect of global warming on precipitation intensity?
less frequent, but more intense precipitation events.
more evaporation dries surface, increasing drought risk, warm air holds more moisture so storms etc. are wetter and more severe (greater flood risk)
how is global warming predicted to affect high latitude regions?
more precipitation, but less in the form of hail/snow. snow melts earlier, increasing flood risk (spring) and drought risk (summer)h
how will global warming affect precipitation in tropical & subtropical (low latitude) regions?
some areas have more precipitation (more intense cyclones/hurricanes), but overall they will likely become drier. (equator=more hot, subtropical HPS band grows)
how do high intensity rainfall events impact crops?
warming means less frequent, more severe rain.
- damages/erodes topsoil and crops
- flash flooding can’t be fully absorbed so earth is dry despite high rainfall
how does drought/heatwaves affect agriculture
-makes farmland unsuitable
-causes crop stress
-can attract new pests that thrive in warm climate
-causes livestock stress, decreasing production & welfare
how does high carbon content affect plants + plant pests?
increases photosynthesis and water retention = higher yield (can reduce nutrition tho)
- this boost also applies to weed species which take nutrients out of soil
- insects eat more vegetation in warm, high carbon climate
how can the impact of climate change on agriculture (crops) be reduced? (3)
- switch to more heat/drought resistant varieties (i.e. types of grape)
- GMO crop species with desirable traits spliced from other species
- shift to other better suited crops
how does melting ice affect albedo?
water has lower albedo than ice, the more ice that melts, the less heat ice reflects. “melt pools” form and its creates positive feedback where melting leads to more melting.
(also reduces pole coverage, reducing overall global albedo)
how does thermal expansion affect sea level?
hot water is less dense, therefore warming ocean surfaces expand and raise sea level
