Carbon Cycle Flashcards
carbon stores
function as sources (adding carbon to the atmosphere) and sinks (removing carbon from the atmosphere)
Carbon exists in different forms, depending on the store:
atmosphere: as carbon dioxide and carbon compounds, such as methane
hydrosphere: dissolved carbon dioxide
lithosphere: as carbonate in limestones, chalk and fossil fuels, as pure carbon in graphite and diamonds
biosphere: as carbon atoms in living and dead organisms
These stores vary in size, capacity and locations. The biosphere contains both terrestrial and oceanic locations
Fluxes
movements of carbon from one store to another; provide the motion in the carbon cycle
Carbon fluxes between the carbon stores of the carbon cycle are measured in either petagrams or gigatonnes of carbon per year. The major fluxes are between the oceans and the atmosphere, and between the land and atmosphere via the biological processes of photosynthesis and respiration. These fluxes vary not only in terms of flow but also on different timescales.
Formation of sedentary rocks
Sediment is deposited in layers in a low-energy environment
E.g. lake
E.g. sea bed
Further layers are deposited and sediment undergoes diagenesis
Diagenesis - /ˌdʌɪəˈdʒɛnɪsɪs/ - the physical and chemical changes that occur during the conversion of sediment to sedimentary rock
The lower layers become compressed and chemical reactions cement particles together
The conversion of loose, unconsolidated sediment into solid rock is known as lithification.
Limestone
Composed of calcium carbonate, and is 40% carbon by weight
80% of lithospheric carbon is found in limestones
Limestone is formed when calcium carbonate is deposited on the ocean floor.
2 ways rocks can be formed
There are two types of ways:
limestone formed in the oceans
The Himalayas form one of the Earth’s largest carbon stores. This is because the mountains started life as ocean sediments rich in calcium carbonate derived from crustaceans, corals and plankton. Since these sediments have been upfolded, the carbon they contained has been weathered, eroded and transported back to the oceans.
carbon derived from plants and animals in shale, coal and other rocks
these rocks were made up to 300 million years ago from the remains of organisms. These remains sank to the bottom of rivers, lakes and seas and were subsequently covered by silt and mud. As a consequence, the remains continued to decay anaerobically and were compressed by further accumulations of dead organisms and sediment. The subsequent burning of these fossil fuels has released the large amounts of carbon they contained back into the atmosphere.
3 types of carbon pump
biological pumps
physical pumps
carbonate pumps
biological pumps
Biological pumps
These move carbon dioxide from the ocean surface to marine plants called phytoplankton through photosynthesis. Phytoplankton are microscopic plants and plant-like organisms drifting or floating in the sea/freshwater along with diatoms, protozoa and small crustaceans.
This effectively converts carbon dioxide into food for zooplantic (microscopic animals) and their predators.
Most of the carbon dioxide taken up by phytoplankton is recycled near the surface. About 30% sinks into deaper waters before being converted back into carbon dioxide by marine bacteria.
Physical pumps
Physical pumps
These move carbon compounds to different parts of the ocean in downwelling and upwelling currents
Downwelling occurs in parts of the ocean where cold, denser water sinks.
These currents bring dissolved bring dissolved carbon dioxide down to the deep ocean.
Once there, it moves in slow-moving deep ocean currents, staying there for hundreds of years.
Eventually, these deep ocean currents, part of the thermohaline. circulation, return to the surface by upwelling.
The cold deep ocean water warms as it rises towards the ocean surface and some of the dissolved carbon dioxide is released back into the atmosphere.
carbonate pumps
These form sediments from dead organisms that fall to the ocean floor, especially the hard outer shells and skeletons of fish, crustaceans and corals, all rich in calcium carbonate.
Terrestrial sequestering
Plants (primary producers in an ecosystem) sequester carbon out of the atmosphere during photosynthesis. In this way, carbon enters the food chains and nutrients cycles of terrestrial ecosystems.
When animals consume plant matter, the carbon sequestered in the plant becomes part of their fat and protein. Respiration, particularly by consumer animals, returns some of the carbon back to the atmosphere.
Waste from animals is eaten by micro-organisms (bacteria and fungi) and detritus feeders (e.g. beetles).
As a consequence, carbon becomes part of these creatures. When plants and animals die and their remains fall to the ground, carbon is released into the soil.
Carbon fluxes within ecosystems vary on two timescales:
Diurnally: during the day, fluxes are positive - from the atmosphere into the ecosystem. The reverse applies at night when respiration occurs but not photosynthesis.
Seasonally: during winter, carbon dioxide concentrations increase because of the low levels of plant growth. However, as soon as spring arrives and plants grow, these concentrations begin to decrease until the onset of autumn.
biological sequestering
All living organisms contain carbon; the human body is about 18% carbon by weight. In plants, carbon dioxide and water are combined to form simple sugars, i.e. carbohydrates. In animals, carbon is synthesised into complex compounds, such as fats, proteins and nucleic acids.
On land, soils are the largest carbon stores. Here, biological carbon is stored in the form of dead organic matter. This matter can be stored for decades or even centuries before being broken down by soil microbes (biological decomposition) and then either taken up by plants or released into the atmosphere.
Soils store between 20% and 30% of global carbon. They sequester about twice the quantity of carbon as the atmosphere and three times that of terrestrial vegetation. The actual amount of carbon stored in some soil depends on:
climate
this dictates the rates of plant growth and decomposition; both increase with temperature and rainfall
vegetation cover:
this affects the supply of dead organic matter, being heaviest in tropical rainforests and least in tundra.
soil type:
clay protects carbon from decomposition, so clay-rich soils have a higher carbon content
land use;
cultivation and other forms of soil disturbance increase the rate of carbon loss
Atmospheric carbon
A fully functioning and balanced carbon cycle is vital to the health of the Earth in sustaining its other systems. It plays a key role in regulating the Earth’s temperature by controlling the amount of carbon dioxide in the atmosphere. This, in turn, affects the hydrological cycle. Ecosystems, terrestrial and oceanic , also depend upon the carbon cycle. All this is a consequence of the fact that the carbon cycle provides the all-important link between the atmosphere, hydrosphere, lithosphere and biosphere. But the carbon balance is being increasingly altered by human actions.
greenhouse affect
It is the increasingly concentration of carbon in the atmosphere that is causing great concern. Carbon dioxide and methane are perhaps the most important of all the greenhouse gases (GHGs). Their increasing presence in the atmosphere in the atmosphere is upsetting the Earth’s natural temperature-control system, resulting in the greenhouse effect.
The greenhouse effect:
Incoming solar radiation 343 Watt per m²
Solar radiation passes through the clear atmosphere. Net incoming solar radiation: 240 Watt per m²
Solar energy is absorbed by the Earth’s surface and warms it. 168 Watt per m²
Some solar radiation is reflected by the atmosphere and Earth’s surface. Outgoing solar radiation: 103 Watt per m²
Some of the infrared radiation passes through the atmosphere and is lost in space. Net outgoing infrared radiation 240 Watt per m²
Some of the infrared radiation is absorbed and re-emitted by the greenhouse had molecules. The direct effect is the warming of the Earth’s surface and the troposphere.
Surface gains more heat and infrared radiation is emitted again.
and is converted into heat causing the emissions of longwave (infrared) radiation back to the atmosphere.
The Earth’s climate is driven by incoming short-wave solar radiation:
31% is reflected back into space by clouds, GHGs and by the land surface
the remaining 69% is absorbed at the Earth’s surface, especially by the oceans
much of this radiation absorbed at the surface is re-radiated as long wave radiation
large amounts of this long-wave radiation are, however, prevented from returning into space by clouds and GHGs
the trapped long-wave radiation is then re-radiated back to the Earth’s surface
Photosynthesis balancing carbon
Photosynthesis by terrestrial and oceanic organisms plays an essential role in keeping carbon dioxide levels relatively constant and thereby helping to regulate the Earth’s mean temperature.
The amount of photosynthesis varies spatially, particularly with net primary productivity (NPP). (This is the amount of organic matter that is available for humans and other animals to harvest or consume). NPP is highest in the warm and wet parts of the world, particularly in the tropical rainforests and in shallow ocean waters. It is least in the tundra and boreal forests.
Soil health balancing carbon
Soil health is an important aspect of ecosystems and a key element in the normal functioning of the carbon cycle. Soil health depends on the amount of organic carbon stored in the soil. The storage amount is determined by the balance between the soil’s inputs (plant and animals remains, nutrients) and its outputs (decomposition, erosion and uptake by plant and animal growth.)
Carbon is the main component of soil organic matter and helps to give soil its moisture-retention capacity, its structure and fertility. Organic carbon is concentrated in the surface layer of the soil. A healthy soil has a large surface reservoir of available nutrients which, in their turn, condition the productivity of ecosystems. All this explains why even a small amount of surface soil erosion can have such a devastating impact on soil health and fertility.
impacts of fossil fuel consumption on climate, ecosystems and the hydrological cycle
Implications for Climate
It is estimated that about half the extra emissions of carbon dioxide since 1750 have remained in the atmosphere. The rest have been fluxed from the atmosphere into the stores provided by the oceans, ecosystems and soils. The rate of carbon fluxing has sped up.
Additional carbon dioxide in the atmosphere and its impact on the greenhouse effect that is largely responsible for a number of climate changes:
a rise in the mean global temperature
more precipitation and evaporation
sudden shifts in weather patterns
more extreme weather events, such as floods, storm surges and droughts
the nature of climate change is varying from region to region - some areas are becoming warmer and drier and others wetter
Implications for Ecosystems
These changes in climate have serious knock-on effects on:
sea level: this is rising because of melting ice sheets and glaciers; many major coastal cities around the world are under threat from flooding by the sea
ecosystems: a decline in the goods and services they provide; a decline in biodiversity; changes in the distributions of species; marine organisms threatened by lower oxygen levels and ocean acidification; the bleaching of corals etc.
Implications for the Hydrological Cycle
increased temperatures and evaporation rates cause more moisture to circulate around the cycle.
Energy security in General
Energy security is achieved when there is an uninterrupted availability of energy at a national level and at an affordable price. All countries seek to achieve this; the most secure energy situation is where the national demand for energy can be completely satisfied by domestic sources. The more a country demands on imported energy, the more it is exposed to risks of an economic and geopolitical kind. Four key aspects of energy security are:
availability
accessibility
affordability - competitively priced energy supply
reliability - uninterrupted
The importance of energy security stems from the fact that energy is vital to the functioning of a country. For example, it: powers most forms of transport, lights settlements, is used by some types of commercial agriculture; warms/cools homes and powers domestic appliances; is vital to modern communications; drives most forms of manufacturing.
Consumption
The consumption of energy is measured in two ways:
in per capita terms, i.e. as kilogrammes of oil equivalent or megawatt hours per person. In general, this measure rises with economic development
by a measure known as energy intensity, which is assessed by calculating the units of energy used per unit GDP. The fewer the units of energy, the more efficiently a country is using its energy supply. In general, energy intensity values decrease with economic development
The energy mix
The energy mix is the combination of different energy sources used to meet a country’s total energy consumption. It’s an important part of energy security, and varies from country to country. There are distinctions between:
domestic and foreign sources
primary and secondary sources
primary = found in nature, not converted/transformed. It can be renewable (water/wind/sunlight) or non-renewable (coal/oil/gas)
secondary = derived from transformation of conversion of primary sources, usually more convenient (electricity)
Factors affecting energy consumption
Factors affecting per capita energy consumption:
physical availability
cost
standard of living
environmental priorities (of governments)
for some, energy policy will be taking the cheapest route to meeting the nation’s energy needs, regardless of the environmental costs. Others will seek to increase their reliance on renewable sources of energy; wile still other will have in place policies that raise energy efficiency and energy saving
climate
Very high levels of consumption in North America, the Middle East and Australia reflect the extra energy needed to make the extremes of heat and cold more comfortable (at home, at work and in public places)
public perception
for some consumers, energy is perceived almost as a human right and therefore to be used with little or no regard for the environmental consequences. Others give priority to minimising the wastage of energy and maximising security
economic development
technology
Energy players
TNCs
The big names in the oil and gas business include Gazprom, ExxonMobil, PetroChina and Royal Dutch Shell. Nearly half of the top 20 companies are state-owned (all or in part) and, therefore, very much under government control. Because of this, strictly speaking they are not TNCs. Most are involved in a range of operations: exploring, extracting, transporting, refining and producing petrochemicals.
Organisation of the Petroleum Exporting Companies
OPEC has 14 member countries*, which between them own about two-thirds of the world’s oil reserves. Because of this, it is in a position to control the amount of oil and gas entering the global market, as well as the prices of both commodities. OPEC has been accused of holding back production in order to drive up oil and gas prices.
*Qatar left in January 2019
Energy Companies
Important here are the companies that convert primary energy (oil, gas, water, nuclear) into electricity and then distribute it. Most companies are involved in the distribution of both gas and electricity. They have considerable influence when it comes to setting consumer prices and tariffs.
Consumers
An all-embracing term, but probably the most influential consumers are transport, industry and domestic users. Consumers are largely passive players when it comes to fixing energy prices.
Governments
They can play a number of different roles; guardians of national energy security and can influence the sourcing of energy for geopolitical reasons.
Mismatch between supply and demand
Coal
Oil
Supply
31% Middle East
20% North America
12% Russia
Demand
34% Asia (12% China)
24% North America
20% Europe (4% Russia)
There is a large mismatch between supply and demand because oil is essential for transport. Petrol/diesel is the main energy source for cars, rail, ships and aircraft.)
Gas
Supply
18% North America
15% Middle East
13% Russia
Demand
27% North America (22% USA)
16% Asia
11% Russia
10% Middle East
Energy pathways- Russia-Europe
Energy pathways are a key aspect of energy security but can be prone to disruption, especially as conventional fossil fuels have to be moved over long distances from sources to markets. Russia is currently the second largest producer of gas. Most of its gas exports go to European countries (Germany, Italy, UK, France, Spain). Russian gas is delivered to Europe mainly through five pipelines:
Countries getting 100% of gas from Russia:
Finland
Estonia
Latvia
Lithuania
66-99%
Bulgaria, Poland, Czech Republic, Slovakia
Geopolitically significant is that three of those pipelines cross Ukraine, a country from which Russia annexed Crimea in 2014. It now occupies parts of eastern Ukraine. Clearly, Ukraine might be in a position of strength here, it could increase the charges for allowing Russian gas to pass through it. It could even stop the gas flows altogether. This potential threat seems to leave Russia with two options:
reduce delivery of gas through these threatened pipelines and export more through two northern pipelines that run through Finland and Poland
annexe the whole of Ukraine
Given the history of strained political relations between Russia and Western Europe, it would appear strategically unwise for EU countries to become heavily reliant on Russian gas. Although the UK still obtains most of its gas from Qatar, it has recently substantially increased its imports of Russian gas in order to offset the declining output of gas from its North Sea gas fields.
Unconventional fossil fuels
Tar Sands
A mixture of clay, sand, water and bitumen (a heavy, viscous oil)
Tar sands have to be mined and then injected with steam to make the tar less viscous so that it can be pumped out.
Oil Shale
Oil-bearing rocks that are permeable enough to allow the oil to be pumped out directly.
Either mined, or shale is ignited so that the light oil fractions can be pumped out.
Shale gas
Natural gas that is trapped in fine-grained sedimentary rocks.
Extracted by fracking: pumping in water and chemicals forces out the gas.
Deepwater oil
Oil and gas that is found well offshore and at considerable oceanic depths.
Drilling takes place from ocean rigs; already underway in the Gulf of Mexico and off Brazil.
Social costs and benifits for the carbon cycle
Social costs and benefits, implications for the carbon cycle, and consequences for the resilience of fragile environments.
It is important to note that exploitation of these unconventional sources has a downside:
they are all fossil fuels, so their use will continue to threaten the carbon cycle and contribute to global warming
extraction is costly and requires a high input of complex technology, energy and water
they all threaten environmental damage, from the scars of opencast mines and land subsidence to the pollution of groundwater and oil spills. Certainly, the resilience of fragile environments will be sorely tested.
this leads to social costs
However, there may also be social benefits, such as energy companies investing in improving local infrastructure in return.
Renewable energy
The global drive to reduce carbon dioxide emissions must involve increasing reliance on alternative sources of ‘clean’ energy, so decoupling economic growth from dependence on fossil fuels. Basically, this means widening the energy mix to include substantial inputs from both renewable and recyclable energy sources.
The main sources of renewable energy today are hydro, wind, solar, geothermal and tidal. The contribution made by these sources to the national energy budget varies from country to country.
Not all countries have renewable energy to exploit for geographic reasons:
not all countries have coasts, strongly flowing rivers or climates with either long sunshine hours or persistently strong winds
Partly because of this, there are very few, if any, countries where renewables might completely replace all the energy derived from fossil fuels.
Other factors reinforcing this include:
the relative financial costs of using non-renewable and renewable energy sources. When oil and gas prices are low, renewables become a more expensive option.
the harnessing of renewables is not without environmental costs. River valleys have to be drowned to create HEP reservoirs, and large areas of land/the offshore zone are covered by solar or wind farms.
While the majority of people believe that we should make greater use of renewable sources, most suddenly go off the idea when constructing a wind or solar farm near them is proposed (NIMBYism)
Recyclable energy
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
Biofules
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.)
Carbon capture and storage
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.
Hydrogen fuel cells
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.
Forms of growing resource demand
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.
Ocean acidification
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.
Forest health
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
UK forests and loss
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.
Impact of forest loss
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
Rising temperatures in the artic
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.
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Declining ocean health
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.
Uncertainty about the future
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
Water conservation management
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
Resilient agricultural strategies
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’
Land use planning
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
Flood risk management
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
Solar radiation managment
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
Mitigation stratagies
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.
Important points about mitigation and adaptations
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.
How does chemical weathering remove carbon from silicate rocks
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.
Where is carbon released from the ocean
outgassing, hotspot volcanoes and subduction zones
