1.1 Hazardous Earth Flashcards
how does the world’s climate system function, why does it change and how can this be hazardous for people?
how does climate vary with latitude?
with distance from the equator:
temps decrease
range of temps increase
precipitation fluctuates
why does temp decrease w distance from the equator?
in areas closer to the poles, incoming solar radiation has a thicker atmosphere to travel through due to the curvature of the Earth. the sun is also at a lower angle in the sky, so solar radiation is spread across a larger area.
name the three global circulatory cells.
hadley cell; ferrel cell; polar cell
describe how the global circulation system works
warm air at Equator rises and moves away; as it cools, it descends at the tropics, creating the hadley cell
cold air at the poles descends; then moves away towards the mid latitudes, creating the polar cell
cold air from poles meets warm air from tropics in the mid latitudes, creating the ferrel cell
what is atmospheric pressure
the weight of the air and the force it exerts on the ground
why do areas of high pressure have low precipitation?
cooled air descends, exerting more pressure on ground and resulting in dry, stable conditions
why do areas of low pressure have high precipitation?
warmed air is unstable and rises, exerting less pressure on ground; as air rises, it cools and cannot hold as much water vapour, resulting in condensation, cloud formation, and precipitation
explain how ocean currents redistribute heat.
surface ocean currents are driven by wind across the top of the water, whereas deep ocean currents are driven by water sinking and rising bc of temp changes
(extra e.g. : cold water from arctic sinks, drawing in warmer water from south)
describe how volcanic activity can affect climate.
they produce ash and sulphur dioxide gas; if these rise high enough, they’ll spread around the Earth’s stratosphere; this blanket will stop some sunlight reaching the Earth’s surface and instead will reflect it back into space; this cools the planet and the average temperature
e.g.1815 eruption of Tambura - in 1816, temps were so cold that 200,000 people died in Europe dur to harvest fail
describe how variation in solar output can affect climate.
black spots on the surface of the sun called sunspots disappear and reappear at different times; lots of sunspots mean more solar energy is being fired out, causing temp increases; less cause temp decreases
e.g. the cooler period known as the Little Ice Age may have been caused by sunspot activity
describe how orbital changes (milankovitch cycles) can affect climate.
over very long periods of time, the Earth’s orbit changes (known as Milankovitch cycles): it is sometime is more circular or more elliptic; sometimes the axis is more upright, or more on the side; sometimes the axis wobbles. these alter the amount of sunlight the Earth receives and where sunlight falls
e.g. these changes over tens of thousands of years would be enough to start or end an ice age
describe how asteroid collisions can affect climate.
every once in a while, an asteroid comes in contact w Earth; these can release huge quantities of vaporised material into the atmosphere, blocking the sun and causing a potential temp. drop of 5-6 degrees - initial ‘impact winter’; can also cause forest fires due to large amounts of CO2 released
e.g. asteroid collision theory considered to account for the extinction of the dinosaurs 65 million years ago.
how can historical sources be used for evidence for natural climate change?
personal diaries e.g. Anglo Saxon chronicles record years of droughts and heavy rainfall
paintings e.g. Painting of River Thames, 1963, during the Little Ice Age
religious records
how can tree rings be used for evidence for natural climate change?
every ring represents a year of growth; wider rings suggest the year was wetter and/or warmer; thinner rings suggest the opposite; black marks = scars from forest fires - suggest year was warmer and/or drier
how can ice cores be used for evidence for natural climate change?
a drill extracts an ice core; bubbles in ice trap ancient atmosphere - ghg content can be measured for particular years, allowing us to model past climate
what human activities produce CO2?
deforestation; power stations; cars
burning of fossil fuels and organic material
what activities produce methane?
cows; landfill sites; rice fields; peat bogs
all organic matter
what is the greenhouse effect?
the natural trapping of sun’s energy in the atmosphere due to the presence of greenhouse gases
what is the enhanced greenhouse effect?
the increased greenhouse effect resulting from human activity, leading to global warming
how does human activity enhance greenhouse effect?
layer of greenhouse gases above atmosphere gets thicker; sun emits short wave radiation which passes through the atmosphere and ghg layer; it is reflected off the surface and becomes long wave radiation; some long wave radiation passes back into space; some is reflected off ghg layer back to earth, heating it up
why do CO2 levels increase over time?
increase in population => increase in demand for energy => increase in no. of power stations => increase in CO2 as fossil fuels are burned ( => enhanced greenhouse effect)
increase in population => increase in demand for food => deforestation esp. tropical rainforests, to provide space for farming or for resources such as palm oil => less CO2 removed from atmosphere; when burned / rotted, they release stored carbon as CO2 ( => enhanced greenhouse effect)`
what is the evidence for how human activity is causing climate change? (surface air temps change, upper ocean temps change, sea level change, arctic sea ice change, mountain glacier change, changes in extreme weather events)
surface air temps have increased - 2016 has been the hottest year recorded; 2010s has been the hottest decade
upper ocean temps have increased - areas of arctic and pacific ocean have increased the most
sea level has increased - by 20cm; floods have damages small pacific islands e.g. Marshall islands
arctic ice has decreased - b 2.8 million sq kms
mountain glaciers are melting/thinning
extreme weather disasters are increasing overall
what are the consequences of climate change on people in the UK?
increase in flooding = flooding damage costs rising from £1 billion a year to £2 to £12 billion by 2080; rising sea levels & more extreme storms = increase in coastal flooding and erosion - threatening homes and transport, more investment in coastal defences to reduce erosion and flooding
domestic tourism likely to grow e.g. coastal resorts like Blackpool
what are the consequences of climate change on people in egypt?
up to 20% less rainfall in parts of egypt and sudan = discharge of nile is reduced = less water for irrigation and conflict w neighbouring countries
global sea level rise = 15% of egypt’s land permanently flooded = 7m people displaced from homes; and less land for agriculture = lower crop yields for commercial and subsistence = undernourishment of poorest and lack of foreign income
