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Flashcards in 2.1 Causes of climate change Deck (75)
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1
Q

Define climate change

A

Any long-term trend or movement in climate detected by a sustained shift in the average value for any climatic element (for example, rainfall, drought, hurricanes).

2
Q

What are greenhouse gases?

A

Atmospheric gases that absorb infrared radiation and cause world temperatures to be warmer than they would otherwise be.

3
Q

Define external forcing

A

A term used to describe processes that impact Earth’s climate system, which originate from outside of the climate system itself, such as variations in solar output.

4
Q

What are the two reasons why climate change can occur?

A

-Changing concentrations of greenhouse gases

-External forcing

5
Q

Explain how changing concentrations of greenhouse gases can lead to climate change

A

-Changing concentrations of greenhouse gases (carbon dioxide, methane and nitrous oxide) affect temperature.

-These greenhouse gases (GHGs) allow sunlight to pass through Earth’s atmosphere but trap the heat that is radiated back towards space (short-wave sunlight is absorbed when it hits the ground, or water, and is later re-emitted as long-wave infrared heat radiation).

-If the concentration of GHG rises above its naturally occurring level, this is the climatic equivalent of putting extra blankets on a bed.

-More heat is retained, resulting in a warmer, more energetic and less predictable climate system.

6
Q

What would the Earth’s temperature be without GHGs?

A

-18°C (too cold for life to have evolved)

7
Q

Explain how external forcing can lead to climate change

A

-Various kinds of external forcing may occur.

-This means the amount of sunlight reaching Earth is reduced or increased.

-This may be because of changes in the Sun’s activity or Earth’s distance from the Sun, for instance.

-Any such change in the global energy balance results in a fall or rise in global mean surface temperature (GMST).

8
Q

Diagram showing the greenhouse effect

A
9
Q

Explain the greenhouse effect (take from other deck?)

A

1) Solar energy enters the atmosphere.

2) As this short-wave energy passes through the atmosphere, it might hit dust particles or water droplets and be scattered or reflected.

3) Only a little short-wave radiation is abosrbed in the atmosphere.

4) Solar energy heats the Earth’s surface, which then radiates long-wave (heat) energy into the atmosphere.

5) Long-wave energy is quite easily absorbed by naturally-occuring greenhouse gases in the atmosphere. Of these, carbon dioxide is by far the most abundant.

6) Some long-wave energy escapes into space.

10
Q

What are the different pieces of evidence of naturally-occuring climate change over time?

A

-Fossil and geological records

-Landscape evidence

-Tree rings

-Agricultural records

11
Q

Explain how fossil and geological records can give evidence about naturally-occuring climate change

A

-Fossils, sedimentary rocks and sediments (containing pollen grains) offer clues about environmental changes over time.

-The geologically recent appearance and later disappearance of woolly mammoths in what is now Europe indicates that periods of cooling and warming occurred in the past.

12
Q

Explain how landscape evidence can give evidence about naturally-occuring climate change

A

Evidence for past sea-level changes is provided by raised beaches (landforms which show sea level used to be higher than it is today) and drowned valleys called rias and fjords. From these, we surmise that Earth’s ice caps have changed size, along with the volume of water stored in oceans.

13
Q

Explain how tree rings can give evidence about naturally-occuring climate change

A

-Trees produce one new ring of growth per year, during the growing season.

-A warmer year results in a wider ring.

-Patterns of slower and faster growth can be observed that allow us to estimate temperatures in the past.

14
Q

Explain how agricultural records can give evidence about naturally-occuring climate change

A

-Historical grape harvest dates have been used to reconstruct summer temperatures in Paris, France, from 1370 to 1879.

-These contribute to our understanding of the so-called ‘Little Ice Age’ (a relatively cold phase from around 1300 to 1850) and the ‘medieval warm period’ (900–1300) that preceded it.

15
Q

In addition to explaining why world temperatures have sometimes risen or fallen, ___ help determine the strength and duration of any changes.

A

Positive and negative feedback processes

16
Q

What are positive feedback loops?

A

-They are knock-on effects in natural systems, which act to accelerate and amplify any changes that have already started to occur.

-When one element of a system changes, it upsets the overall equilibrium, or state of balance, thereby leading to changes in other elements that reinforce what is happening.

17
Q

What are negative feedback loops?

A

-These occurs when a system adjusts itself in ways that lessen or cancel out the effect of the original change.

-In this case, feedback has triggered changes in other elements, which act in the opposite direction from the initial change.

-As a result, equilibrium or balance is restored.

18
Q

Diagram of a positive feedback loop showing a possible way the climate system could respond to more carbon dioxide being added to the atmosphere (for example, as a result of fossil fuel use).

The first scenario suggests accelerated warming as various system changes take place, which strengthen one another.

A
19
Q

Diagram of a negative feedback loop showing a possible way the climate system could respond to more carbon dioxide being added to the atmosphere (for example, as a result of fossil fuel use).

A

.

20
Q

Which is more concerning for scientists: positive or negative feedback loops?

A

-There is widespread concern among the world’s climate scientists that positive feedback effects associated with human emission of carbon dioxide will be far greater than negative feedback effects in the coming decades.

-As a result, there is a significant risk of a high rise in GMST (of 4–6°C) occurring by 2100.

21
Q

What are the different reasons for variations in solar radiation?

A

-Volcanic emissions and global dimming

-Changes in solar output

-Changes in the Earth’s orbit

-Cosmic collisions

22
Q

Explain how volcanic emissions and global dimming can be a reason for variations in solar radiation

A

-Major past volcanic eruptions have led to a short-lived period of global cooling lasting for one or two years only.

-This is because of ash and dust particles being ejected high into the atmosphere, blanketing Earth and reducing incoming insolation.

-Mount Pinatubo’s 1991 eruptions caused global temperatures to drop temporarily by about 0.5°C.

23
Q

Explain how changes in solar output can be a reason for variations in solar radiation

A

-A variety of output cycles have been detected in the amount of energy emitted by the Sun.

-The most obvious of these is an 11-year sunspot activity cycle.

-Sunspots are dark areas where intense magnetic storms are happening, which increase solar output.

-A long period with almost no sunspots lasting from 1645 to 1715 is called the Maunder Minimum.

-It has been linked to the cooler conditions that existed during the Little Ice Age.

24
Q

Explain how changes in the Earth’s orbit can be a reason for variations in solar radiation

A

-Three known cycles occur in Earth’s orbit around the Sun, resulting in warming and cooling over long periods of time as incoming levels of solar radiation change.

-Firstly, every 100,000 years, Earth’s orbit changes from spherical to elliptical, changing the solar input.

-Secondly, Earth’s axis is tilted at 23.5 degrees, but this changes over a 41,000-year cycle by between 22 and 24.5 degrees, also affecting solar input.

-Thirdly, Earth’s axis wobbles, changing over 22,000 years, bringing further climate change.

-These orbital cycles are usually termed Milankovitch cycles (the theory of astronomical climate forcing was developed by Milutin Milankovitch).

25
Q

Explain how cosmic collisions can be a reason for variations in solar radiation

A

-Large asteroids colliding with Earth may have caused dramatic, though short-lived, climate change in the past.

-The mass extinction of the dinosaurs is thought to have been caused by a large meteor strike 65 million years ago.

-Its explosive impact would have thrown up an enormous volume of debris.

-A vast dust cloud may have blocked sunlight and prevented photosynthesis for up to 10 years.

-This would have been long enough for the food chains that sustained the dinosaurs to collapse entirely.

26
Q

Define global dimming

A

-Suspended particulate matter in the atmosphere can reflect solar energy back into space and so have a net cooling effect.

-This phenomenon can occur naturally because of volcanic emissions but can also be caused by human pollution too – meaning that fossil fuel burning may be both warming and cooling the planet at the same time.

27
Q

Graph showing the ineratction between the three Milankovitch cycles

A
28
Q

Explain the albedo effect

A

-During periods when Earth has grown warmer in the past, temperature changes may have accelerated because of the loss of ice cover.

-Ice has a high albedo of around 80 percent, which means it reflects four-fifths of all incoming solar radiation.

-If some white-colored sea ice melts in the Arctic, for instance, darker-colored water will be revealed.

-The water has a lower albedo because of its dark color and, consequently, it absorbs more heat.

-As it warms, the water becomes more likely to melt any remaining sea ice.

-This results in the opening up of more areas of the open ocean, and so the process repeats.

-When the water grows warmer, so too do the air masses that are in contact with it.

-The result is accelerated warming of the atmosphere.

29
Q

Define albedo

A

-How much solar radiation a surface reflects.

-White surfaces have the highest albedo, or reflectivity.

30
Q

How can a positive feedback loop exacerbate the albedo effect?

A

-This positive feedback process means that even a small change in sea ice coverage can have a significant impact on global climate potentially.

-In theory, even a small reduction in sea ice cover could lead eventually to an ice-free Arctic.

31
Q

How do geologists believe the Earth’s ice cover has changed over time?

A

-There are periods in Earth’s past when the planet has been entirely ice free; at other times the majority of land has been covered with ice. Geologists believe that:

•Earth may have become a giant ‘snowball’ during two distinct Cryogenian ice ages that occurred around 650 to 750 million years ago

•During much of the Paleocene and early Eocene geological epochs (about 65–35 million years ago), ‘hothouse’ conditions meant the poles were probably free of ice caps.

-Feedback cycles linked with albedo changes occurring both on land and water may have played an important role in producing both outcomes.

32
Q

Give an example of a negative feedback loop in which the climate system could self-correct if Arctic ice began to melt

A

1)Ice melts to expose the darker ocean which absorbs more sunlight.

2)As the ocean warms, there will be increased levels of evaporation.

3)This will create more cloud, especially in the lower atmosphere.

4) The light-coloured cloud has a high albedo and reflects incoming solar radiation (much as the ice used to).

5) As a result, less light reaches and is absorbed by the ocean surface.

6) The temperature of the water falls, as does that of the air mass in contact with it.

33
Q

Diagram of a negative feedback loop in which the climate system could self-correct if Arctic ice began to melt

A
34
Q

What is methane?

A

-A very powerful greenhouse gas, enormous volumes of which are stored in frozen soils in Earth’s permafrost regions.

-Around one quarter of Earth’s surface is affected by continuous or sporadic permafrost, including tundra, polar and mountain regions

35
Q

Explain the relationship between methane and permafrost

A

-Some researchers estimate that the amount of methane in permafrost equates to more than double the amount of carbon currently in the atmosphere.

-The effects of permafrost melting may also be magnified potentially over time in positive feedback loops.

-In theory, this could take Earth’s climate beyond a ‘tipping point’.

36
Q

What is permafrost?

A

-Ground (soil or rock and included ice) that remains at or below 0°C for at least two consecutive years.

-The thickness of permafrost varies from less than 1 metre to more than 1.5 kilometres.

37
Q

How much permafrost is there on Earth?

A

-Globally, permafrost covers 23 million square kilometres (mostly in Earth’s northern hemisphere).

-It formed during past cold glacial periods and has persisted through warmer interglacial periods, including the Holocene (the last 10,000 years).

-However, reports indicate that it is now shrinking at an alarming rate.

38
Q

Describe the evidence that indicates that permafrost is shrinking at an alarming rate

A

-One estimate shows that the tundra climate zone (where most permafrost is found) has shrunk in size by about 20 per cent since 1980.

-According to scientists at NASA, temperatures in Newtok, Alaska, have risen by 4°C since the 1960s, and by as much as 10°C in winter months.

-Based on current evidence, it is likely that widespread melting of permafrost will have occurred by 2100.

39
Q

Need more info/statistics on climate change?

A
40
Q

What has the IPCC’s 2013 assessment stated?

A

-It is ‘virtually certain’ humans are to blame for ‘unequivocal’ global warming.

-Atmospheric concentrations of the greenhouse gases (GHGs) carbon dioxide, methane and nitrous oxide are at levels ‘unprecedented in at least the last 800,000 years’.

41
Q

Why is it believed that humans are to blame for climate change?

A

-Proof of emissions

-Industrial/agricultural practices

-Carbon dioxide data

42
Q

Proof of emissions as a reason why it is believed that humans are to blame for climate change

A

-Carbon dioxide emissions have been rising since 1750, the start of Europe’s Industrial Revolution, from a level of 280 ppm (parts per million) to 406 ppm at the start of 2017.

-This represents an increase of around 45 percent.

-Even more worryingly, if you convert other GHGs (methane, nitrous oxide) into their equivalent amounts of CO2, then you find that we have reached a level in excess of 470 ppm of CO2 equivalents).

43
Q

Industrial and agricultural practices as a reason why it is believed that humans are to blame for climate change

A

This is because population growth and economic development have led to: worldwide use of carbon-rich fossil fuels as an energy source; widespread deforestation; and enhanced methane emissions derived from livestock (bovine flatulence) and the decomposition of organic wastes in landfill sites.

44
Q

Carbon dioxide data as a reason why it is believed that humans are to blame for climate change

A

-A steep trend line can be viewed in carbon dioxide data: there was gradual growth up to the early 1900s and then very rapid growth.

-Older evidence comes from ‘fossil air’ trapped in ice.

-Permanent ice in high mountains and polar ice caps has built up from snow falling over hundreds of thousands of years.

-Cores 3–4 kilometres long have been extracted from the Vostok ice sheet in the Antarctic, producing ice that is more than half a million years old and containing bubbles of ancient air.

-After analysing the evidence, scientists believe that carbon dioxide and methane concentrations are now higher than at any time in the last 800,000 years

45
Q

The highest polluters in terms of total carbon output are ___

A

High- and middle-income countries with large populations, including China, the USA, India, Russia, Japan and Germany.

46
Q

What are the three key things to remember when comparing countries (pollution in terms of carbon output)

A

-Data showing per capita carbon footprints reveal a very different pattern.

-The highest figures belong to oil-rich Middle Eastern states including Qatar and Kuwait.

-The USA and EU countries have relatively high per capita carbon footprints but so too do many Caribbean countries where wood is burned widely.

-China has a relatively low per capita carbon footprint.

47
Q

Define per capita footprint

A

The amount of carbon dioxide emissions an average person in a country is responsible for as they go about their everyday life.

48
Q

Why might our perception of which countries should be held most to account for anthropogenic climate change alter depending on whether we look at carbon stock or carbon flow data – or both?

A

-Because current data shows the present-day anthropogenic carbon flow generated by different countries.

-However, data showing which countries are responsible for most of the anthropogenic carbon stock already in the atmosphere reveal a very different pattern; Germany, for example, may be to blame for around 6.9 per cent of all anthropogenic carbon emissions dating back to 1750.

-In 2015, Germany accounted for only 2.3 per cent of current carbon flow.

49
Q

Why is it important to consider globalization and trade when thinking about global patterns of carbon emissions?

A

-Some high-income countries claim to have reduced their carbon emissions in recent years.

-However, falling domestic emissions mask the fact that many developed countries now import much of their food and consumer goods from other countries since deindustrialization and globalization took place.

-Although they have reduced their own emissions, they have increased their overall carbon consumption through importing energy-intensive goods produced in emerging economies.

-Some people believe countries should be held accountable for the carbon emitted by goods they consume but which were made in other places.

-If we factor in global trade, then a very different pattern of responsibility for climate change emerges.

-Germany’s annual share of global carbon emissions rises to almost 10 per cent, for instance.

50
Q

Define anthropogenic carbon flow

A

-The current amount of carbon emission released annually by a country (for example, due to fossil fuel burning and cement making) produced in each nation.

-The figure can be adjusted upwards to factor in the carbon equivalents of other greenhouse gas emissions (methane and nitrous oxide).

51
Q

Define anthropogenic carbon stock

A

The total size of the store of anthropogenic carbon emissions released into the atmosphere since industrialization began around 1750.

52
Q

Define deindustrialization

A

-The loss of traditional manufacturing industries in some high-income countries due to their closure or relocation elsewhere.

-Since the 1960s, many industries have all but vanished from Europe and North America. Instead, they thrive in Asia, South America and, increasingly, Africa.

53
Q

What role does the USA play in global GHG emissions?

A

-The USA is the world’s second biggest emitter, generating just under one fifth of all anthropogenic GHGs.

-This is despite its population size being less than 5 per cent of the global total.

54
Q

What action has the USA taken to reduce its GHG emissions?

A

-In recent years, its carbon emissions have fallen by around 10 percent.

-The main reason for this is a shift from coal to gas burning within the USA’s energy mix.

-A gas-fired plant produces half the emissions of a coal-fired one.

-Under the Obama administration, the USA began taking greater action to address its emissions.

-However, the Trump administration is more skeptical of the need for action.

55
Q

What role does China play in global GHG emissions?

A

-China became the world’s largest carbon emitter in 2007 on account of widespread industrialization since the 1970s.

-A massive programme of poverty alleviation (requiring more, not less, energy) remains the country’s priority.

-China now contributes around one quarter of world emissions while accounting for one fifth of world population.

-Its emissions rose by almost 10 per cent in 2011 alone, primarily due to higher coal consumption.

56
Q

What action has China taken to reduce its GHG emissions?

A

-China’s leaders want to reduce the rate at which their emissions rise and have made a (non-binding) pledge to reduce the carbon intensity of the country’s growth by adopting more renewable energy into their mix.

-For instance, China spent US$10 billion on wind turbines in 2010 – about half of all global spending.

-Such actions will not lead to a cut in total emissions but will curb the rate at which China’s emissions grow.

57
Q

What role does India play in global GHG emissions?

A

-Currently, it contributes more than 5 percent of global CO2 emissions.

58
Q

What role does Qatar play in global GHG emissions?

A

-The oil-rich desert state of Qatar has exceedingly high per capita emissions.

-The country’s great oil wealth is used to fund high energy usage, including lavish use of air conditioning.

59
Q

What role does Japan play in global GHG emissions and what action have they taken to reduce these emissions?

A

-Japan’s emissions have increased in the 2010s as a result of a substantial increase in the use of fossil fuels in power generation.

-This is part of a reaction against the use of nuclear power following the accident at Fukushima in 2011.

-However, they have decreased in recent years.

60
Q

What role do low-income countries play in global GHG emissions and what action have they taken to reduce these emissions?

A

-Many of the world’s least developed countries (LDCs), such as Somalia, continue to make a negligible contribution to anthropogenic GHG emissions, although economic changes in some African countries, such as Nigeria and Kenya, mean that energy consumption there is rising.

-People in some poor countries may have a high per capita carbon footprint because of their reliance on wood-burning stoves as a source of heat and energy for cooking.

61
Q

Define carbon intensity

A

-The amount of CO2 emitted per unit of GDP.

-If a country’s carbon emissions rise less slowly than its GDP is increasing, this suggests some action is being taken to reduce emissions at the same time as industrial output is increasing.

62
Q

What is renewable energy?

A

Wind, solar and tidal power sources that result from a flow of energy from the Sun.

63
Q

Why is climate change a ‘wicked problem’?

A

-There is uncertainty over the operation of feedback loops.

-Nor can we predict with any certainty what kinds of economic and demographic changes will take place globally or in particular countries.

-As a result, climate change presents us with a wicked problem which – because of its complexity – defies attempts to establish exactly what its effects would be.

-Unfortunately, this uncertainty is seized upon by climate change skeptics as a reason to avoid taking any action to reduce GHG emissions.

64
Q

What other factors introduce greater complexity to climate change models?

A

-Natural climatic cycles like the El Niño Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) are independent phenomena that operate naturally on shorter, decade-long timescales.

-They introduce year-to-year climatic variability into numerous different local contexts.

-Both phenomena can bring colder conditions temporarily to places that are predicted to get warmer on account of long-term climate change.

65
Q

How do other factors like the El El Niño Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO) further complicate climate change models?

A

-This complicates our understanding of long-term climate change and can undermine public faith in IPCC expert predictions.

-People who lack deeper scientific understanding of the issues may – quite understandably but erroneously – view one unusually cold winter as ‘irrefutable proof’ that the planet cannot be warming up.

66
Q

What is a ‘wicked problem’?

A

-A challenge that cannot be dealt with easily due to its scale and/or complexity.

-Wicked problems arise from the interactions of many different places, people, things, ideas and perspectives within complex and interconnected systems.

67
Q

What is the El Niño Southern Oscillation (ENSO)?

A

-A sustained sea surface temperature anomaly across the central tropical Pacific Ocean.

-It brings a change in weather conditions that can last from two to seven years.

-Along with La Niña events, El Niño events are part of a short-term climate cycle that brings variations in climate but only for a few years.

68
Q

Diagram showing a summary of some of the many different influences on climate change processes and the high levels of complexity and uncertainty that affect future predictions of climatic change

A
69
Q

In which atmospheric layer does weather take place?

A

Troposphere

70
Q

The Earth is a ___ system

A

Closed

71
Q

Explain how ocean currents transfer heat around the Earth

A

-Surplus energy exists between the tropics and is moved wia wind and water currents

-Ocean currents transfer warm water towards the poles and colder water towards the equator

-Prevailing winds help to drive ocean currents whilst they also transfer hot and cold air masses between places

72
Q

Explain short-wave vs. long-wave radiation

A

-Short-wave light radiation from the sun hits the Earth’s surface (the soil, rocks and plants, etc.) and is transformed into long-wave heat radiation that eventually escapes into space.

-If some of the heat did not escape the Earth would heat up. For the Earth to maintain its stable temperature the outgoing long-wave radiation must match the incoming short-wave radiation.

73
Q

Explain a human factor that causes global dimming

A

-Air pollution decreases the amount of sunlight reaching the planet

-This is because aerosols or small particles are formed from pollutants that reflect and absorb radiation

-Subsequently, the radiation is not able to reach the ground

74
Q

Natural gas is ___% methane

A

90

75
Q

The angle of ___ is highest at the equator

A

Incidence