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Question 1

Alternatives to fossil fuels

Answer 1

The global drive to reduce carbon emissions and to decouple fossil fuels from economic growth must involve increasing reliance on alternative sources of
‘clean’ energy. Renewable and recyclable energy sources are part of the multi-energy approach to energy security and protecting the carbon cycle.

Question 2

Renewable and recyclable energy

Answer 2

The main forms of renewable energy being harnessed today are hydro, wind, solar (mainly via photovoltaic cells), geothermal and tidal. All are up and running, but their contributions to the energy budget vary from country to country. It is a simple fact of physical geography that not all countries have renewable energies to exploit. For example, not all countries have coasts or ‘hot rocks’; not all countries have warm climates with long sunshine hours; not all countries have permanently flowing rivers or persistently strong winds. Furthermore, hydro and tidal power are the only sources that could provide base-load electricity.

Question 3

It is frequently claimed that renewable sources of energy will be the saviour of the global energy challenge. However, some sobering facts are often overlooked:

Answer 3

• There are very few, if any, countries where renewables might completely replace all the energy currently derived from fossil fuels. The most likely are those with good hydro resources.
• As oil prices tumbled during 2015, renewables - with their slightly higher costs - became less attractive as an option.
• Upping the importance of renewables is likely to have significant impacts on the environment: more valleys would be drowned to create HEP reservoirs; large areas of land and the offshore zone would be covered by wind and solar farms.
• It is particularly frustrating that, while the majority of people believe that we must make greater use of renewable sources, most suddenly go off the idea when there is a proposal to construct a wind or solar farm close to where they live. They protest even when the wind farm is to be located well offshore!
  Another unpalatable fact is that those countries with high levels of energy consumption will have no option but to look to nuclear energy to generate their

electricity supply in a reasonably carbon-free manner.

Question 4

An added attraction is that nuclear waste can be reprocessed and reused, thereby making it a recyclable energy source. Nonetheless, nuclear power does have a downside. There are issues related to:

Answer 4

• safety, as exemplified by the incidents at Chernobyl (Ukraine) and Fukushima (Japan)
• the security of nuclear-powered stations in an era of international terrorism
• the disposal of highly toxic radioactive waste with an incredible long decay life
• the technology involved, which effectively means that the nuclear option is only open to the most developed countries
• costs - although operational costs are relatively low, the costs of building and decommissioning are high.

Question 5

The UK energy mix
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Answer 5

The UK government is very mindful of the need to become energy secure and to play its part in reducing global carbon emissions. Figure 5.17 clearly shows that when it comes to primary energy consumption, while there has been a complete shift away from a direct use of coal, the reliance on oil and natural gas seems to have settled at a rather high level, providing close to 80 per cent of the UK’s primary energy. Much of the petroleum is used by transport and most of the natural gas is used to generate electricity. Forecasts suggest that this is unlikely to change much in the near future. The electricity shown in Figure 5.17 is in fact ‘primary electricity’ generated by renewable (hydro, wind, solar, photovoltaic and geothermal) and recyclable (nuclear) energy.

Question 6

The UK energy mix
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Answer 6

Figure 5.18 shows that a significant amount of electricity is still generated by coal-fired power stations, while oil has virtually ceased to be used in this way.
Natural gas produces slightly more electricity than nuclear energy. The contribution by renewables remains disappointingly small.
One piece of good news about the UK’s energy budget is that today we consume less energy than we did in 1970, despite a population increase of some 6.5 million. The UK is now more efficient, both in producing energy and in using it. The rise of a less energy-intensive service sector at the expense of industry has also played a part. Households now use twelve per cent less energy while industry uses 60 per cent less. However, these savings have been offset by transport, particularly the big increase in the number of vehicles on the road and of flights. It now looks as if the UK will be using the same amount of energy in 2030 as it does today.

Question 7

Biomass:

Answer 7

Organic matter used as a fuel, especially in power stations for the generation of electricity.

Question 8

define Biofuel:

Answer 8

A fuel derived immediately from living matter, such as agricultural crops, forestry or fishery products, and various forms of waste (municipal, food shops, catering, etc.). A distinction is made between primary and secondary biofuels:
* Primary biofuels include fuelwood, wood chips and pellets, and other organic materials that are used in an unprocessed form, primarily for heating, cooking or electricity generation.
* Secondary biofuels are derived from the processing of biomass and include liquid biofuels such as ethanol and biodiesel, which can be used by vehicles and in industrial processes.

Question 9

Biofuels

Answer 9

Of all the energy sources, fuelwood perhaps has the longest history. However, while fuelwood remains important in the energy mix of some parts of the world, biomass has recently come into prominence with the commercial use of a number of relatively new biofuels.
They have now joined the ranks of recyclable energy, alongside nuclear energy.
Increasing attention is now being paid to the growing of biofuel crops as a way of decreasing the consumption of fossil fuels. These so-called energy crops include wheat, maize, grasses, soy beans and sugar cane. In the UK, the two main crops are oilseed rape and sugar beet. Most are converted into ethanol or biodiesel and used mainly as a vehicle fuel.
There is no doubt that biomass and biofuels have much to commend them as a ‘green’ source of energy. Their increasing use is not without costs, however. The most notable of these is the fact that a hectare of space used to grow energy crops is a hectare less for growing much-needed food in a hungry world. The experience of Brazil shows that this competition for agricultural space also has unfortunate environmental costs.

Question 10

Biofuels in Brazil

Answer 10

Brazil took action in the 1970s to diversify its energy sources in order to combat concerns about its energy security. It has since invested in alternative energy sources, initially in hydroelectricity and more recently in biofuels. Today, four per cent of its energy comes from renewable sources, and approximately 90 per cent of new passenger vehicles sold in Brazil contain flex-fuel engines that work using any combination of petrol and sugar cane ethanol. This has led to a significant reduction in the country’s carbon dioxide emissions.
Brazil is now the world’s largest producer of sugar cane. It has also become the leading exporter of sugar and ethanol. Since 2003 the area planted with sugar cane has increased significantly and is set to double by 2018. Sugar cane production is concentrated in the central southern region. The result has been the displacement of other types of agriculture, particularly cattle pasture. The knock-on effect has been to create a need for replacement pastures. This, in turn, has resulted in the large-scale clearance of the tropical rainforest (Figure 5.19). This deforestation is, in effect, now cancelling out the reduction in carbon dioxide emissions related to the increasing use of ethanol.

Question 11

Skills focus: Emissions comparison

Answer 11

Possibly the fairest way of comparing the emissions of different fuels is to see how they all perform when they are used to generate electricity. Surprisingly, every fuel produces greenhouse gases (GHGs), but in varying quantities. This is because account needs to be taken of what are known as life cycle’ emissions. These include not just the emissions that occur while electricity is being generated, but also those GHGs given off during the construction and decommissioning of generating plants. So, for example, coal-fired electricity releases large emissions of GHGs during the operational stage, whereas with wind, hydro, solar and nuclear energy, emissions occur mainly during construction and decommissioning. In short, there are no carbon-free forms of energy.
Figure 5.20 shows the emissions per gigawatt hour for nine fuels. Proportional bars are a good technique for representing such data as they make for an easy visual comparison. Another important point is that the data are derived from no less than twenty independent emissions studies, so the range of results is shown for each fuel. The figures show how relatively ‘green’ the renewable sources of energy are compared with fossil fuels.

Question 12

Figure 5.21 conveys three important messages about the UK:

Answer 12

• greenhouse gas emissions have fallen over the last twenty years
• energy supply remains the largest contributor, but its share has begun to decline with gas replacing coal and gas as the main fuel in electricity generation
• transport’s contribution has not changed, for the simple reason that it remains highly dependent on the burning of petroleum and diesel.

Question 13

Radical technologies to reduce carbon emissions

Answer 13

Greater use of renewable and recyclable sources of energy clearly offers one pathway to a more sustainable energy future. But are there any radical new technologies on the horizon that might play a part in reducing carbon emissions in the near future? Let’s take a quick look at two: carbon capture and storage (CCS) and hydrogen fuel cells.

Question 14

Carbon capture and storage

Answer 14

It is widely accepted that coal will never cease to be a part of the global energy budget: it is an attractive energy source as it is abundant and cheap. Because of this, and its wide global distribution, it can often be locally sourced, particularly by poorer developing countries.
CCS involves ‘capturing’ the carbon dioxide released by the burning of fossil fuels and burying it deep underground (Figure 5.22). This technique promises the greatest savings in emissions where coal is being used to generate electricity. A slightly different technique, which ‘scrubs’ some of the carbon dioxide out of natural gas is already used quite widely, either at the point of production or at energy facilities from which gas 1s distributed to consumers.

Question 15

It is frustrating that the implementation of this apparently simple idea is throwing up considerable challenges:

Answer 15

• It is expensive because of the complex technology involved.
• No one can be sure that the carbon dioxide will stay trapped underground and that it will not gradually leak to the surface and enter the atmosphere.

Question 16

Hydrogen fuel cells 1

Answer 16

Although it is chemically simple and an abundant element, hydrogen does not occur naturally as a gas on Earth. It is always combined with other elements, for example with oxygen in water. Currently, most hydrogen is extracted from other forms of fuel, such as oil and natural gas. Hydrogen is high in energy,
and an engine that burns pure hydrogen produces almost no pollution (Figure 5.23). Since the 1970s, NASA has used liquid hydrogen to propel space shuttles and other rockets into orbit. Hydrogen fuel cells have also powered the shuttles’ electrical systems.
A fuel cell combines hydrogen and oxygen to produce electricity, heat and water. It will produce electricity as long as fuel (hydrogen) is supplied, and it will never lose its charge.

Question 17

Fuel cells are a promising technology for use as:

Answer 17

• a source of heat and electricity for buildings
• a power source for electric vehicles.

Question 18

Hydrogen fuel cells 2

Answer 18

They operate best on pure hydrogen, so fuels like natural gas, ethanol or even petrol need to be
‘reformed’ in order to produce it. In the future, hydrogen could also join electricity as an important energy carrier, namely delivering energy in a usable form to consumers.
Given where we are today, it is the second of these radical technologies that offers the brightest prospect of reducing carbon emissions. There seems to be a fair measure of certainty about the role it is just beginning to play in the context of transport. It does seem to be a very promising way of meeting future energy needs in an environmentally safe manner.
A world with no need to burn any fossil fuels is highly improbable. However, a world deriving much of its energy from renewable and recyclable sources, and making full use of the hydrogen cell, does promise relatively little disturbance of the carbon cycle and its stores and fluxes. It would also promise a longer human survival on the Earth.

Question 19

Land conversion:

Answer 19

Any change from natural ecosystems to an alternative use; it usually reduces carbon and water stores and soil health.

Question 20

Growing resource demands

Answer 20

The terrestrial biosphere sequesters about a quarter of fossil fuel CO, emissions annually, directly slowing down global warming.
Growing demands for food, fuel and other resources have led to contrasting regional trends from land conversion.

Question 21

Deforestation

Answer 21

Forests cover 30 per cent of the Earth’s land area, although only fifteen per cent are ‘natural’ primary forests (found in Canada, Alaska, Russia and the northwestern Amazon basin). Forests absorb rainfall and increase groundwater storage. Even small forest losses can disrupt natural weather patterns and the longer-term climate, enhancing or even creating destructive flood and drought cycles (Figure 6.1).

Question 22

The main driver of deforestation,

Answer 22

is the increasing demand for commodity production. Half of all current deforestation is for soy, palm oil, beef and paper production. Other causes of land conversion are: dams and reservoirs, infrastructure and opencast mining. By 2015, 30 per cent of all global forest cover had been completely cleared, 20 per cent degraded and the rest fragmented. Approximately 13 million hectares are deforested annually, equivalent to 36 football fields of trees lost per minute

Question 23

The common method of either large tract or small plot deforestation is by

Answer 23

burning trees by two methods: Clear cutting removes all primary forest, while slash-and-burn agriculture eventually allows growth of secondary forest.

Question 24

Impact of defrestation on:
Impact on water cycle

Answer 24

• Reduced intercepted rainfall storage by plants; infiltration to soil and groundwater changes.
• Increased raindrop erosion and surface run-off, with more sediment eroded and transported into rivers.
• Increased local
  ‘downwind’
  aridity from loss of ecosystem input into water cycle through evapotranspiration.

Question 25

Impact of defrestation on: Impact on carbon cycle

Answer 25

• Reduction in storage in soil and biomass, especially above ground.
• Reduction of CO2 intake through photosynthesis flux.
• Increased carbon influx to atmosphere by burning and decomposing vegetation.

Question 26

Regional trends include:

Answer 26

• Temperate forests such as in the UK and USA have a long history of exploitation; 90 per cent was deforested by the nineteenth century.
• Boreal forests have been increasingly threatened since the mid-twentieth century, for example by oil and tar sands production in Russia and Canada.
• Tropical forests have lost half their area since the 1960s, especially in Africa and South America.
  However, remote sensing shows that Indonesia has recently overtaken Brazil in the rate of deforestation, mainly for palm oil production and logging, as shown in Figure 6.2. Around 25 per cent of the rainforest has been clear-felled or burnt in 25 years, with Borneo (Kalimantan) most affected. Much of South East Asia suffers from the ‘brown haze’ created.

Question 27

Afforestation

Answer 27

In 2014, the New York Declaration on Forests set a global target to restore 350 million hectares of deforested and degraded forest landscapes by 2030.
Afforestation and reforestation is beneficial for COz sequestration but can also be controversial in its impacts on landscape character as well as on carbon, water and soil systems. Monocultures of commercial trees, such as in palm oil plantations and non-indigenous species, often store less carbon, use more water and are disease prone. China’s Three-North Shelterbelt Project
- a 4,500 km green wall of trees designed to reduce desertification - demonstrates many of these issues.

Question 28

Remote sensing:

Answer 28

Surveillance by satellites such as Landsat generates data that can authenticate, or refute, official government data.

Question 29

Afforestation:

Answer 29

Planting trees on land that has never had forest, or has been without forest for a long time.

Question 30

Reforestation:

Answer 30

Planting trees in places with recent tree cover, replacing lost primary forests.

Question 31

Grassland conversion

Answer 31

There are two main types of grassland, shown in Figure 6.4, covering 26 per cent of global land area:
* Temperate grasslands
* Tropical grassland or savannah

Question 32

• Temperate grasslands

Answer 32

have no trees and a seasonal growth pattern related to a wide annual temperature range. Those with fertile chernozem soils, an important carbon store, are prized for agriculture and hence suffer most degradation. Only two per cent of North America’s prairies remain from land conversion, with similar issues in Russia’s steppe biome.

Question 33

• Tropical grassland or savannah

Answer 33

have scattered trees, such as Africa’s Serengeti and Brazil’s Cerrado. Land conversion is increasing despite often infertile soils.
The carbon and water cycles are disrupted in grasslands that are used too intensively for animals or when ploughed up. Rapid increases in population and changes from nomadic to sedentary farming, coupled with the effects of climate change and poor management, are the drivers of change. Soil and ecosystem degradation is now a worldwide issue, resulting in carbon store loss.

Question 34

Ocean acidification p1

Answer 34

Oceans are an important carbon sink, but their function as a fossil fuel gas sink is increasingly changing their overall pH and acidifying them.
Ecosystems are being affected, such as the complex food web based on coral.
For the past 300 million years, up to the early nineteenth century, the average oceanic pH was 8.2, dropping to 8.1 by 2015. Since the Industrial Revolution began, the pH of surface seawater has decreased by 0.1, a 30 per cent drop. By the end of the twenty-first century, the additional decrease in surface ocean pH may be between 0.06 and 0.32. Reefs, the foundation stone of coral ecosystems, stop growing if the pH is less than 7.8.
When ecosystem resilience is reduced, the potential for crossing a threshold is increased. Acidification increases the risk of marine ecosystems reaching a critical threshold of permanent damage. Ocean acidification impacts will be amplified because of other stressors, such as warming temperatures, destructive cyclones and pollution. One key factor is the speed of acidification: organisms may be able to adapt and be more resilient if changes are slow enough.

Question 35

Ocean acidification p2

Answer 35

The Arctic Ocean is likely to be first affected because of its low pH, threatening its vulnerable ‘cold’ corals.
Coral reefs globally already show bleaching from warming temperatures (see Figure 4.12, page 92).
Acidification affects shell-building marine organisms because carbonic acid reacts with carbonate ions in the water to form bicarbonate. Reduced carbonate ions mean animals like coral expend more energy building their shells, resulting in thinner, more fragile shells. The more acid the water is, the more it dissolves carbonate shells, weakening them and allowing attack from bio-erosion by molluscs, worms and sponges. Major functions of the ecosystem, especially reef building, may collapse. This could lead to an irreversible changed state and net reef loss by the mid-twenty-first century if current levels of carbon emissions continue.

Question 36

Geographical Information System (GIS):

Answer 36

Maps with ‘layers’ of information are an important tool in analysing place characteristics.

Question 37

pH:

Answer 37

A logarithmic measure of acidity or alkalinity. A value of 7 means neutral; above this the pH is alkaline, below this it is more acidic.

Question 38

Ocean acidification:

Answer 38

The decrease in the pH of the Earth’s oceans caused by the uptake of carbon dioxide from the atmosphere.

Question 39

Ecosystem resilience:

Answer 39

The level of disturbance that ecosystems can cope with while keeping their original state.

Question 40

Critical threshold:

Answer 40

An abrupt change in an ecological state. Small environmental changes can trigger significant responses. Negative and positive feedback loops reinforce or undermine changes once an alternative stable state has become established.

Question 41

Enhanced greenhouse effect:

Answer 41

The intensification of the natural greenhouse effect by human activities, primarily through fossil fuel combustion and deforestation, causing global warming.

Question 42

Oceanic processes

Answer 42

Research on oceanic processes is generally at a ‘frontier’ stage, hence the uncertainty about the consequences of warming and acidification for both marine ecosystems and the people relying on them.

Question 43

Climate change
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Answer 43

There is now unequivocal evidence of humans triggering the enhanced greenhouse effect with resulting climate changes.
2015 was an exceptional year for climate change: it was the first full year to exceed the key benchmark for global warming of 1 °C above pre-industrial levels.
Many parts of the world experienced unusual weather patterns associated with global warming: severe droughts in parts of Africa, India and Pakistan; flooding in Europe and the USA; and very warm temperatures in Siberia, northern Russia, and North America’s east coast. The UK had the wettest and warmest December since 1910, resulting in severe flooding.
Researchers blame a combination of long-term anthropogenic influences combined with the ‘spike’ of the strongest El Niño in a generation.

Question 44

Climate change
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Answer 44

Climate change may increase the frequency of drought due to shifting climate belts, such as in the Amazon.
This may have an impact on the role of plants, especially forests, as carbon stores.
There are more than 30 different climate zones on Earth, simplified as equatorial, tropical, temperate and polar. However, they are not static, and warming by 2°C could lead to five per cent of the Earth’s land area shifting to a new climate zone. There is already evidence of an expansion of subtropical deserts, and a poleward movement of stormy wet weather in the mid-latitudes.

Question 45

There is already evidence of an expansion of subtropical deserts, and a poleward movement of stormy wet weather in the mid-latitudes.

Answer 45

• Northern middle and high latitudes will undergo more changes than the tropics.
• In the tropics, mountainous regions will experience bigger changes than low-altitude areas.
• The coldest climate zones will largely reduce in size, while dry regions will increase.
• Cool summers will change to hot summers in many places.

Question 46

Key concept: The role of forests in climate regulation

Answer 46

All forests help control the climate at local, regional and global scales. They absorb and store rainfall, then add to atmospheric humidity through transpiration. Positive feedback operates: deforestation decreases rainfall locally and contributes to global warming, which in turn dries out the rainforest and causes it to die back.

Question 47

The amazons changing climate

Answer 47

The forest acts as a global and regional regulator, pumping 20 billion metric tonnes of water into the atmosphere daily, 3 billion more than the River Amazon discharges into the ocean. The forest’s uniform humidity lowers atmospheric pressure, allowing moisture from the Atlantic Ocean to reach further inland than areas without forest cover. Rain-bearing winds travel west until deflected by the Andes and normally transport moisture south to Buenos Aires and east to São Paulo.
However, since 1990 a more extreme cycle of drought and flood has developed in Amazonia, with a wetter rainy season, linked to shifts in the ITCZ. Rainfall has appreciably decreased downwind of deforested areas, with São Paulo suffering a water crisis.
Droughts in 2005 and 2010 greatly degraded much of the rainforest, which had already been stressed by decades of deforestation. The regional water cycle has been altered.

Question 48

Inter-tropical convergence zone (ITCZ):

Answer 48

A concentration of warm air that produces rainfall as part of a global circulation system (the Hadley cell). It moves north and south across the equator seasonally. Small shifts in its location can cause drought.