Carbon Cycle Flashcards

Question

Recyclable energy

Answer 1

Recyclable Energy (Nuclear) In addition, 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. A possible plus here is that nuclear waste can be reprocessed and reused, thereby making it into a recyclable energy source. Downsides of nuclear energy: risks to do with safety and security (accidents and terrorism) the disposal of radioactive waste with an incredibly long decay life the technology involved is complex and therefore its use is only an option for developed countries although the operational costs are low, the costs of constructing and decommissioning power stations are high

Answer 2

Of all the energy sources used by humans, 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. This is organic matter used as a fuel, for example in power stations for the generation of electricity. The growing of biofuel crops is being increasingly recognised as one way of reducing both the burning of fossil fuels and carbon dioxide emisions. The most widely grown biofuel crops include wheat, maize, grasses, soy beans and sugar cane. In the UK, the two main crops are oilseed rape and sugar beet. Most of these two crops are converted into ethanol or biodiesel, which are mainly used as a vehicle fuel. The downside: each hectare of farmland used to grow energy crops means a hectare less for growing much-needed food in an increasingly hungry world. They are supposedly carbon neutral, since the carbon dioxide they produce when burnt, is only that they took from the environment whilst growing, but there is uncertainty over how carbon neutral they actually are. (Since what was on the land before them, e.g. a forest, is destroyed.)

Answer 3

Carbon Capture and Storage This involves 'capturing' the carbon dioxide released by the burning of fossil fuel, and burying it deep underground. Unfortunately, it is an expensive process because of the complex technology involved. There is also some uncertainty over whether the stored carbon will stay trapped underground or if it will slowly leak to the surface and into the atmosphere. Since it is widely accepted that fossil fuel will continue to provide most of the world's primary energy, development of the carbon capture and storage technology must be given a high priority, as must also the slightly different technology that 'scrubs' some of the carbon dioxide out of exhausts produced by the burning of fossil fuels.

Answer 4

Hydrogen Fuel Cells These combine hydrogen and oxygen to produce electricity, heat and water. They will produce electricity for as long as hydrogen is supplied and never lose their charge. They are a promising technology for use as a source of heat and electricity for buildings, and as a power source for electric vehicles. The challenge with this technology is finding a cheap and easy source of hydrogen. Although it is a simple and abundant chemical element, it does not occur naturally as a gas. It is always combined with other elements, for example with oxygen in water. Once this challenge has been met, these cells offer the real prospect of reducing carbon emissions. A world free from the need to burn fossil fuels for energy is highly improbable. However, a world deriving much of its energy from renewable and recyclable sources and making full use of the hydrogen fuel cell, does promise much less disturbance of the carbon cycle, its stores and fluxes.

Answer 5

Deforestation The clearance of forests both for their timber and for the land they occupy. In the latter case, the land is mainly cultivated to provide grazing for livestock or to produce cash crops. However, it is not all bad news, as afforestation and reforestation is under way in temperate latitudes. This is helping to offset the loss of tropical rainforest 'services', but n the case of afforestation much is taking place on what was agricultural land. There has been a net gain in more than 500,000 ha of forest area in China for 1990-2015, as well as gains of 250,000-500,000 ha in the USA and India. A net gain of 50,000-250,000 was experienced in Russia, Turkey, Iran, Italy, France and Spain. There was little change in the rest of Europe, northern Africa and the Middle East and the remainder of Central Asia. However, there were losses in South America, Central Africa, and Australia, and losses of more than 500,000 ha in Brazil and Indonesia. Grassland conversion Temperate and tropical grasslands have also become heavily exploited by agriculture. Both grassland types have suffered as a result of overexploitation. The simple act of ploughing leads to an immediate loss of both carbon dioxide and moisture, as well as a change in runoff characteristics. Urbanisation No land-use conversion is greater than that associated with urbanisation. Much space has already been taken over and many ecosystems completely destroyed by the insatiable demand for space needed to accommodate a rapidly rising urban population and their widening range of economic activities. Of all forms of development, none is having a more disruptive impact on the carbon and water cycles than urbanisation. Towns and cities are focal points of both GHG emissions and intense water demand. Clearly, these changes vary from place to place and as a consequence so does their overall impact on carbon stores, soil health and the water cycle. In some locations, the impact is considerable, in others it is minimal if at all.

Answer 6

Ocean acidification involves a decrease in the alkalinity/pH of oceans, caused by the uptake of carbon dioxide from the atmosphere, released by burning fossil fuels. It occurs because oceans are a carbon sink (absorbs more carbon from the atmosphere than it releases). (The carbon sink function is the precursor to a particular environment becoming a carbon store.) Up until the early 19th century, the average ocean pH was 8.2 but this had fallen to 8.1 by 2015. This may seem a minuscule change, but the mean values disguise the fact that there has been a large fall in the pH of surface waters. There has been a decrease everywhere since the 1700s and 1990s, which generally increases with distance from the equator, (though there is less of a change directly next to Antarctica and the Arctic). The greatest change is of less than -0.1 in an arc between north Scotland and southern Greenland. Coral reefs, an important component of ocean life, stop growing when the pH is less than 7.8. The situation is now approaching the point that there is a real risk of some marine ecosystems and their goods and services passing the critical threshold of permanent damage. In the case of coral reefs, they are also being threatened by the rise in surface water temperatures. The widespread bleaching of the Great Barrier Reef of Australia is a clear indication that this threat has become a reality.

Answer 7

Like ocean acidification, the declining health of forests is also the outcome of the enhanced greenhouse effect and consequent climate change. The health of the world's forests as a carbon store is being challenged in three ways: by deforestation by the poleward shift of climatic belts by increasing drought The first and second encourage the third. Amazon droughts The Amazon rainforest acts as a giant climate regulator, pumping 20 billion tonnes of water into the atmosphere each day. This is 3 billion tonnes more than the River Amazon discharges into the Atlantic Ocean. The forest's uniform humidity lowers atmospheric pressure, allowing moisture from the Atlantic to reach almost across the continent. However, since 1990, a cycle of extreme drought and flooding has been observed. Droughts in 2005 and 2010 greatly degraded much of the forest already stressed by prolonged and large-scale deforestation. In short, the diminishing health of the tropical rainforest means that it is: declining as a carbon store sequestering less carbon dioxide from the atmosphere, thereby exacerbating the greenhouse effect playing a diminished role in the hydrological cycle

Answer 8

UK Forests After centuries of deforestation, the forest cover of the UK had been reduced from an estimated original figure of 80% to less than 10% by the end of the 19th century. The Forestry Commission was set up in 1919 to remedy the country's shortage of timber. it started to plant fast-growing exotic conifers, such as Sitka spruce, on the moors of Wales, the Scottish Highlands and the English Lake District and Highlands. Today 13% of the UK's land surface is now forested. In recent years, the cultivation of exotic conifers has given way to the planting of indigenous species. Today, there is much less emphasis on the commercial production of timber and more on the environmental benefits of restoring a forest cover close to the original. So as more and more countries put the brake on deforestation and instead begin programmes of reforestation (as in the taiga), so forest loss eventually begins to have what might be seen as a positive impact. Unfortunately, the same cannot be said for rising temperatures and declining ocean health. Their negative impacts are beginning to be understood, but as of yet little remedial action is being taken. Will it really take, as the Kuznets curve suggests, further increases in wealth before the tide turns from exploitation to conservation. Human wellbeing is enhanced through a more sustainable interaction with ecosystems. The support of different players, especially governments and NGOs, is important. However, the reality is that players have different attitudes towards sustainability and on environmental issues. Attitudes are largely determined by motives - if these are economic than their attitudes towards the environment may not be sympathetic.

Answer 9

Impacts of Forest Loss It is now widely understood that the impacts of deforestation are global in scale and not just confined to deforested areas. Forests are important for: sequestering carbon dioxide from the atmosphere storing carbon transferring moisture from the soil back into the atmosphere by evapotranspiration Kuznets Curve It looks as if the environmental Kuznets curve is correct in suggesting that, as they reach higher levels of development and wealth. societies approach a tipping point when the costs of resource exploitation become fully realised and are set against the benefits of resource conservation and protection. UK pre-industrial revolution, remote Amazonia, Indonesia pre 1970s - little income, little environmental degradation Indonesia today, China in the 20th century - increase in income, large increase in environmental degradation. Rising income worsens environmental impacts. China today - shallower gradient, almost at peak environmental degradation, middle level income UK today - (post-industrial service economy), rising income reduces environmental impact

Answer 10

The Arctic The Arctic plays an important role in global climate, as its sea ice regulates evaporation and precipitation. What has happened here over the last few decades serves as a warning to the rest of the planet: temperatures have risen twice as fast as the global average there has been a considerable loss of sea ice; the North-west Passage is now open to summer navigation much melting of the permafrost carbon uptake by terrestrial plants is increasing because of a lengthening growing season a loss of albedo as the ice that once covered the land surface gives way to tundra, and tundra gives way to taiga. Sunlight that was previously reflected back into space by the white surface is now being increasingly absorbed by the ever darkening land surface. In other words, it is encouraging further climate warming. In terms of human wellbeing, there has been both positives and negatives. The warming climate is opening up previously ice-bound wilderness areas to tourism. the exploitation of mineral resources, particularly Arctic oil and as, is becoming more feasible. However, climate warming is disrupting and perhaps annihilating traditional ways of life, for example the the fishing and hunting of Inuits in North America and the Sami reindeer herders of northern Eurasia. Although scientific understanding of the enhanced greenhouse effect is increasing, there is still much uncertainty. As a consequence, there is a commensurate degree of caution when it comes to making global projections. .

Answer 11

The decline in ocean health caused by acidification and bleaching is resulting in changes to marine food webs. In particular, fish and crustacean stocks are both declining and changing their distributions. Such changes are being particularly felt by developing countries. the FAO estimates that fishing supports 500 million people, 90% of whom live in developing countries Millions of fishing families depend on seafood for income as well as food. Seafood is also the dietary preference of some wealthier countries, notably Iceland and Japan. Aquaculture is on the rise, but its productivity is also being affected by declining pH values and rising temperatures. Tourism is another activity under threat, particularly in those countries, for example in the Caribbean, where coral reefs, now showing signs of degradation, have traditionally attracted scuba-diving tourists. The rising sea level is yet another consequence of climate change that threatens the very survival of tourism and its coastal infrastructure, as for example the Maldives and Seychelles. The costs of strengthening coastal defences can often exceed the financial resources of poorer coastal countries.

Answer 12

There is much uncertainty over the future, which raises many questions, particularly: the level of GHG emissions - will they continue to rise? GHG concentration levels in the atmosphere - is there a limited capacity? the resilience of other carbon sinks and stores- what are their capacities and could they store more? the degree of climate warming - how much warmer? feedback mechanisms such as the release of carbon from peatlands and thawing permafrost - what volumes of carbon are likely to be released? the rate of population growth - when, if ever, will it level off? the nature and rate of economic growth - will it always be so carbon-based? the harnessing of alternative energy sources - will fossil fuels be completely replaced? the possible passing of tipping points relating to aspects as forest dieback and irreversible alterations to the thermohaline circulation - will disaster be sure to follow? Any forecasting of global futures should be undertaken with greatest caution, since there is still so much unknown. How should we react to further global warming? There are two different courses of action: Adaptation: changing our ways of living in such a manner that we are able to cope with most, if not all, the outcomes of global warming living with the problem, not solving it Mitigation: reducing or preventing GHG emissions by devising new technologies and adopting low-carbon energies (renewables and recyclables) tackling the root cause of the problem

Answer 13

Water Conservation and Management Benefits Fewer resources used, less groundwater abstraction Attitudinal change operates on a long-term basis: use more grey (recycled) water Costs and Risks Efficiency and conservation cannot match increased demands for water Changing cultural habits of a large water footprint needs promotion and enforcement by governments, e.g. smart meters

Answer 14

Resilient Agricultural Systems Benefits Higher-tech, drought-tolerant species help resistance to climate change and increase in diseases Low-tech measures and better practices generate healthier soils and may help carbon dioxide sequestration and water storage: selective irrigation, mulching, cover crops, crop rotation, reduced ploughing, agroforestry. More 'indoor' intensive farming Costs and risks More expensive technology, seeds and breeds unavailable to poor subsistence farmers without aid High energy costs from indoor and intensive farming Genetic modification is still debated, but frequently used to crease resistant strains, e.g. rice and soya Growing food insecurity in many places adds pressure to find 'quick fixes'

Answer 15

Land-use Planning Benefits Soft management: land-use zoning, building restrictions in vulnerable flood plains and low-lying coasts Enforcing strict runoff controls and soakaways Costs Public antipathy Abandoning high-risk areas and land-use resettling is often unfeasible, as in megacities such as Dhaka, Bangladesh or Tokyo-Yokohama A political 'hot potato' Needs strong governance, enforcement and compensation

Answer 16

Flood-Risk Management Benefits Hard-management traditionally used: localised flood defences, river dredging Simple changes can reduce flood risk, e.g. permeable tarmac Reduced deforestation and more afforestation upstream to absorb water and reduce downstream flood risk Costs and Risks Debate over funding sources, especially in times of economic austerity Land owners may demand compensation for afforestation or 'sacrificial land' kept for flooding Constant maintenance is needed in hard management, e.g. dredging; lapses of management can increase risk Ingrained culture of 'techno-centric fixes': a disbelief that technology cannot overcome natural processes

Answer 17

Solar Radiation Management Benefits Geoengineering involves ideas and plans to deliberately intervene in the climate system to counteract global warming The proposal is to use orbiting satellites to reflect some inward radiation back into space, rather like a giant sunshade It could cool the Earth within months and be relatively cheap compared with mitigation Costs and Risks Untried and untested Would reduce but not eliminate the worst effects of GHGs: for example, it would not alter acidification Involves tinkering with a very complex system, which might have unintended consequences or externalities Would need to continue geoengineering for decades or centuries as there would be a rapid adjustment in the climate system if SRM stopped suddenly

Answer 18

Carbon taxation The carbon price floor tax sets a minimum price companies have to pay to emit carbon dioxide. It was unpopular with both industry and environmental groups and had a debatable effect on emissions. In 2015, the policy was 'frozen' Lower road taxes for low-carbon-emitting cars were scrapped in 2015 In 2015, oil and gas exploration tax relief was expanded to support fossil fuels, hence the fracking debate Renewable Switching The relationship between the big energy producers and the government dictates the amount of switching from fossil fuels to renewables and nuclear power. Renewables provide intermittent electricity, while fossil fuels provide the continuous power essential for our current infrastructure. The Climate Change Levy, designed in 2001 to encourage renewable energy investment and use, was cut in 2015 Energy Efficiency The Green Deal scheme encouraged energy-saving improvements to homes, such as efficient boilers and lighting, and improved insulation. It was scrapped in 2015. Energy suppliers must comply with the Energy Company Obligation scheme to deliver energy-efficient measures to households. Afforestation Tree planting in the UK is increasing, helping carbon sequestration. It involves the Forestry Commission, charities such as the National Trust and the Woodland Trust, landowners and local authorities. The Big Tree Plant campaign encourages communities to plant 1 million new trees, mostly in urban areas. Carbon Capture and Storage (CCS) Few actual geologic CCS projects exist globally, despite its potential. Canada's Boundary Dam is the only large scale working scheme. In 2015, the UK government cancelled its investment in full-scale projects at gas- and coal-powered plants in Peterhead in Scotland and Drax in Yorkshire, respectively.

Answer 19

Important Points about Adaptation and Mitigation There is a range of possible human intervention options and targets that runs from 'business as usual' (but perhaps making some adaptations) to 'aggressive mitigation'. Even with strong mitigation measures, there is no guarantee that even if emissions are halved by 2080 the mean global temperature will not rise by more than 2°C. RCPs (recommended concentration pathways) are four different concentrations of GHGs in the atmosphere identified by the IPCC (Inter-governmental Panel on Climate Change). Here are the possible outcomes in 2100: Business as usual Emissions continue rising at current rates. RCP 8.5 Temperature rise: as likely as not to exceed 4°C -> businesses impacted by climate change Sea level rises by half to one metre More acidic oceans Some mitigation Emissions rise until 2080, then fall. RCP 6.0. Temperature rise: likely to exceed 2°C More heatwaves, changes in rainfall patterns and monsoon systems Carbon dioxide concentrations three to four times higher than pre-industrial levels Strong mitigation Emissions stabilise at half today's levels by 2080. RCP 4.5 Temperature rise: more likely than not to exceed 2°C Arctic summer sea ice almost gone 'Aggressive mitigation' Emissions halved by 2080. RCP 2.6 Temperature rise: not likey to exceed 2°C Business impacted by policy change May require 'negative emissions' (removing CO2 from the air) before 2100 CO2 concentration falling before end of century Climate impacts generally constrained, by not avoided Reduced risk of 'tipping points' and irreversible change If mitigation, at whatever level, is to have any change of success, it not only requires concerted actions at a national level but, more critically, it requires effective international agreements. Global warming is a global problems requiring global action. The latter point was first accepted by the Kyoto Protocol in 1997, an international agreement which aimed to cut GHG emissions by 5% by 2012. Since then, the reduction targets have been revised upwards and emissions have been reduced. It remains to be seen whether enough is being done or whether the global mitigation strategy should be made even more aggressive. It has to be said that not every country has been enthusiastic about signing up to the succession of agreements tabled since 1997. (Also Copenhagen meeting 2009; Paris meeting in 2015 (COP21) - agreement in 2016) The most recent of these, the Paris Agreement of 2016, aims to keep the rise in global temperature to less than 2°C above its pre-industrial level. The Agreement now has 140 national signatures. Among the more reluctant signatories are the three largest producers of GHGs: China, India and the USA (withdrew in 2017) The attitude of a large proportion of the world's population to the threat of global warming is one of indifference. TNCs may express concern, but are often found wanting when it comes to taking appropriate action. When it comes to government attitudes, those whose contributions to GHG emissions are relatively small are vociferous in drawing attention to those countries that are large contributors.

Answer 20

1CO₂ Dissolution – Atmospheric CO₂ dissolves in rainwater, forming carbonic acid (H₂CO₃). Reaction with Silicate Rocks – The weak acid reacts with silicate minerals (e.g., feldspar), breaking them down. Formation of Bicarbonate Ions – The reaction releases dissolved ions (e.g., Ca²⁺, HCO₃⁻), which are carried to oceans by rivers. Carbon Storage in Ocean – In the ocean, calcium (Ca²⁺) and bicarbonate (HCO₃⁻) combine to form calcium carbonate (CaCO₃), which is used by marine organisms to build shells. Long-Term Carbon Storage – When these organisms die, their shells settle on the seafloor, forming limestone, which locks away carbon for millions of years.

Answer 21

outgassing, hotspot volcanoes and subduction zones