The carbon cycle and energy security

HOW DOES THE CARBON CYCLE OPERATE TO MAINTAIN PLANETARY HEALTH?

• The carbon cycle is the cycle by which carbon moves from one Earth sphere (atmosphere, hydrosphere, lithosphere and biosphere) to another. It is a closed system but is made up of interlinked subsystems which are open and have inputs and outputs.
• Carbon stores function as sources (adding carbon to the atmosphere) and sinks (removing carbon from the atmosphere)
• Carbon fluxes (also known as flows or processes) are movements of carbon from one store to another; they provide the motion in the carbon cycle.
• Carbon exists in different forms, depending on the store:
• Atmosphere - as carbon dioxide (CO2) and carbon compounds, such as methane (CH2)
• Hydrosphere - as dissolved CO2
• Lithosphere - as carbonates in limestone, chalk and fossil fuels, as pure carbon in graphite and diamonds
• Biosphere - as carbon atoms in living and dead organisms
• The important distinction in the biosphere is between terrestrial and oceanic locations.
• Carbon fluxes, or flows, are measured in either pentagrams or gigatonnes of carbon per year.

• The major fluxes are between the oceans and the atmosphere, and between the land and the atmosphere via the biological processes of photosynthesis and respiration. 
• These fluxes vary not only in terms of their rates of flow but also on different timescales.
• Most of the Earth's carbon is geological and results from:
• The formation of sedimentary carbonate rocks (limestone) in the oceans. E.g. the Himalayas is one of the Earth's largest carbon stores as the mountains started life as ocean sediments rich in calcium carbonate derived from organisms. Since these sediments have been upfolded, the carbon they contained has been weathered, eroded and transported back to the oceans.
• Carbons 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 bottoms 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 to the atmosphere.
• There are two natural processes releasing carbon:
• Carbon dioxide in the atmosphere reacts with moisture to form weak carbonic acid. When this falls as rain, it reacts with some of the surface minerals and slowly dissolves them, i.e. there is chemical weathering

• Pockets of carbon dioxide exist in the Earth's crust. Volcanic eruptions and earthquakes can release these gas pockets. This outgassing occurs mainly along mid-oceanic ridges, subduction zones and at magma hotspots.
• Carbon sequestration - is the process by which carbon dioxide is removed from the atmosphere and held in solid or liquid form. It is the process that facilitates the capture and storage of carbon.
• The oceans are the Earth's largest carbon store (50x greater than the atmosphere). Most of the oceanic carbon is stored in marine algae, plants and coral. The rest occurs in dissolved form.
• Carbon pumps are the processes operating in the oceans that circulate and store carbon.
• There are three types of oceanic carbon pump:
• Biological pumps move carbon dioxide from the ocean surface to marine plants (phytoplankton) by a process known as photosynthesis.This effectively converts carbon dioxide into food for zooplankton (microscopic animals) and their predators. Carbon is then passed up the food chain by consume fish and zooplankton, which in turn release CO2 back into the water and atmosphere. Most of the carbon dioxide taken up by phytoplankton is recycled near the surface. About 30% sinks into deeper waters before being converted back into carbon dioxide by marine bacteria.

• Physical pumps move carbon compounds to different parts of the ocean in downwelling and upwelling currents. Downwelling occurs in those parts of the ocean where cold, denser water sinks. These currents bring dissolved carbon dioxide down to the deep ocean. Once there, it moves in slow-moving deep currents, staying there for hundreds of years. Eventually, these deep ocean currents, part of the thermohaline circulation (the global system of surface and deep ocean currents driven by temperature and salinity differences between different parts of the ocean), return to the surface by upswelling. 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 form sediments from dead organisms that fall to the ocean floor. Marine organisms may utilise calcium carbonate (CaCO2) to make hard outer shells and inner skeletons, such as some plankton species, coral, oysters and lobsters. When organisms die and sink, many shells dissolve before reaching the sea floor sediments. This carbon becomes part of the deep ocean currents. Shells that do not dissolve build up slowly on the sea floor, forming limestone sediments such as those in the white cliffs of Dover.

• Plants sequester carbon out of the atmosphere during photosynthesis. In this way, carbon enters the food chains and nutrient cycles of terrestrial ecosystems. When animals eat plants, carbon sequestered in the plant becomes part of their fat and protein. Respiration, particularly by animals, returns some of the carbon back to the atmosphere. Waste from animals is eaten by micro-organisms and detritus feeders. 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; at night the reverse situation applies
• Seasonally - during winter, carbon dioxide concentrations increase because of the low levels of plant growth. As soon as spring arrives and plants grow again, those concentrations begin to decrease until autumn.
  
• On land, soils are the biggest 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 back into the atmosphere.

• Soils store between 20% and 30% of global carbon. The actual amount of carbon stored in a 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 the 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
• A fully functioning and balanced carbon cycle 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 on the carbon cycle. 
• The carbon cycle is being increasingly altered by human actions and activities.
• Carbon dioxide and methane are perhaps the most important of all the greenhouse gases. Their increasing presence in the atmosphere is upsetting the Earth's natural temperature-control system, resulting in the greenhouse effect.

• The sun is the natural driver for almost all of the Earth's atmospheric energy. Energy is received as incoming solar radiation (light) from the sun. Dark surfaces on the Earth absorb this solar radiation and then radiate it back as heat. The greenhouse gases absorb and reflect back some of the radiated heat from the Earth's surface. By retaining this heat, they keep the average Earth's surface temperature at 15 degrees rther than -6 degrees - warm enough to sustain life on Earth.
• The Sun's energy enters the atmosphere as short wave energy; about 31% is reflected back into space by clouds, greenhouse gases and the land surface. The remaining 69% is absorbed at the Earth's surface, especially by the oceans.
• Heat energy is reflected back towards space from the Earth's surface, but at a longer wavelength, which means that it has difficulty travelling through the denser gases such as carbon dioxide and methane, and so the atmosphere absorbs the heat. The trapped long-wave radiation is then re-radiated back to the Earth's surface, which warms the lower atmosphere, the land and the sea and keeps it habitable.
• Any changes in the concentrations of carbon in the atmosphere will affect the natural greenhouse effect, changing global temperatures and the global hydrological cycle and resultant precipitation patterns.

• Photosynthesis by terrestrial and oceanic organisms plays an essential role in keeping carbon dioxide levels relatively constant and thereby helping to regulte the Earth's mean temperature.
• Anything that affects the level of phytoplankton in the ocean, or the land area covered by 'forest' will have an impact on carbon sequestration rates and therefore an effect on the composition of the atmosphere. Warming temperatures are causing melting of Arctic ice and seasonal thaws are lasting for longer. This is allowing phytoplankton to photosynthesise for longer, creating algal booms in Arctic waters and more carbon sequestration as a result.
• Net primary productivity (NPP) - the amount of organic matter that is available for humans and other animals to harvest or consume. The amount of biomass produced by plants minus the energy lost through respiration.
• The amount of photosynthesis varies spatially, particularly with the NPP.
• Tropical rainforests are the most productive areas as a result of their hot, wet conditions and year long growing season. The Tundra are the least productive biomes as a result of their extreme temperatures and lack of rainfall. 
• Coral reefs and mangroves are also productive and both thrive in warm, shallow waters where sun penetration is great and there are plenty of nutrients.
• Temporally productivity also varies with slow growth in the winter and much of the carbon being stored in the soil as leaves decompose, rather than in the biomass.

• 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 animal 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 its fertility. In addition it supports micro-organisms and these in turn maintain the nutrient cycle, breakdown organic matter and provide pore spaces which improves the soil's ability to allow infiltration and storage and enhances plant growth as it allows water to move through it more easily. 
• Carbon is therefore required for the nutrient and water cycle to operate properly and it improves the resilience of the soil to wetter conditions as water can infiltrate and percolate more easily which leads to less soil erosion and flooding.
• In the winter there will be more decay of leaf litter and therefore the release of carbon to the atmosphere, whereas during periods of spring growth the rate of sequestration will increase and the amount of carbon in the atmosphere will fall.
• A response to climate change and increasing temperatures would lead to more photosynthesis and more growth and therefore more carbon sequestration. 

• Fossil fuel combustion is the number one threat to the global carbon cycle. It is changing the balance of both the carbon stores and the fluxes.
• Since the Industrial Revolution human activity has transferred considerable amounts of carbon from the fossil fuel stores (slow exchanges) to the fast category since it releases the carbon as carbon dioxide immediately. 
• It is estimated that about half the extra emissions of carbon dioxide since 1750 have remained in the atmosphere. The rest has been fluxed from the atmosphere into the stores provided by the oceans, ecosystems and soils. The rate of carbon fluxing has speeded up. It is that additional carbon 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, others wetter

• 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 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
• The hydrological cycle - increased temperatures and evaporation rates cause more moisture to circulate around the cycle

WHAT ARE THE CONSEQUENCES FOR PEOPLE AND THE ENVIRONMENT OF OUR INCREASING DEMAND FOR ENERGY?

• Long-term energy security mainly deals with timely investments to supply energy in line with economic developments and environmental needs
• Short-term energy security focuses on the ability of the energy system to react promptly to sudden changes in the balance between energy demand and supply
• Energy securirty includes 4 important aspects:
• Reliable and uninterrupted energy supply
• Affordable and competitively priced energy supply
• Energy mix dependent on domestic rather than imported sources of energy
• Accessible and available energy supply
• The consumption of energy is constantly increasing as a result of development, rising living standards and population growth.
• The consumption of energy is usually expressed in per capita terms using one of the following measures: kilograms of oil equivalent per year, gigajoules per year, exajoules per year or megawatt hours per uear.
• Energy intensity - a measure of how efficiently energy is being used - calculated as units of energy used per unit of GDP. Energy intensity decreased with economic development

• Every country satisfies its energy needs in a particular way, known as its energy mix.
• A critical aspect is the mix of primary energy sources used to generate electricity. These sources include:
• Non-renewable fossil fuels or carbon fuels, such as oil, natural gas and coal
• Recyclable fuels such as nuclear energy, general waste and biomass
• Many types of renewable energy, such as wind, geothermal, water and solar
• Globally, fossil fuels account for over 80% of the energy mix.
• Energy security increases as dependence on imported sources of energy decreases. A high dependence on imported energy puts a country at risk from sudden threats, e.g.:
• Artificial and abrupt hikes in energy prices
• Supplies cut off by military campaigns or civil unrest

• Access to and consumption of energy resources depends on:
• Physical availability - If energy resources have to be imported, then transport costs are likely to add to the overall cost of energy to the consumer. Rising costs are likely to be a downward pressure on energy consumption. Is exploitation of energy resources going to be technically difficult and expensive?

• Technology - modern technology can help in the exploitation of energy resources that are not so readily accessible, for example deposits of oil and gas that require deep drilling through a contorted geology. This is likely to encourage energy consumption. Much of the modern technology that is now part of everyday living is energy thirsty.
• Cost - physical exploitation, processing (converting a primary into a secondary resource), delivery to the consumer are all costs. Relatively low energy costs may be expected to boost energy consumption.
• Economic development - the same energy costs may be perceived as expensive in one country and acceptable in another. The public perception will depend very much on the level of economic development and the standard of living. The higher these are, the less sensitivity to energy costs.
• Climate - very high levels of consumption in North America, the Middle East and Australia reflect the extra energy required to make the extremes of heat and cold more comfortable, not only in the home but also at work and in public places. 
• Environmental priorities - It might be that, out of concern for the environment in general, and about carbon emissions in particular, a government does not take the cheapest route to meeting its energy needs. Also, the cost of a 'green' energy policy could have a slightly depressing impact on consumption, as would any government's drive to raise energy efficiency and energy saving.

• Meeting the demand for energy involves energy pathways from producer to consumer.
• At the supply end, energy players include energy companies and the governments of energy-producing countries.
• There are governments at the demand end also, as well as a range of consumers. 
• There are also players involved at various points along the pathways, such as the companies responsible for the movement and processing of energy
• TNCS - nearly half of these companies are state-owned. They are involved in a range of operations.
• OPEC - has 12 member countries and between them owns around 2/3 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.
• Energy companies - important here are the companies that convert primary energy 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 - the most influential consumers are transport, industry and domestic users. Consumers are largely passive players when it comes to fixing energy prices.

• Governments - they are the guardians of national energy security and can influence the sourcing of energy for geopolitical reasons.

Mismatch between fossil fuel supply and demand:

• Coal - The mismatch between the distributions of coal production and consumption appears to be small, in that China and the USA are the largest producers and consumers. This reflects the fact that coal is characterised by high transport costs relative to a low energy density.
• Oil - Well over half of the supply comes from the two international groups of OPEC and North America. The relatively small amount of oil production in oil-thirsty Europe clearly signals one important mismatch. All four BRIC countries are shown to rank among the oil producers. Three of the oil producers (USA, China and India) are also major importers of oil. There is high demand for oil as a transport fuel; there is no substitute, as there is with coal and gas.
• Gas - Global gas production is dominated by the USA and Russia. Some of the leading gas producers are also leading gas consumers.

• Such mismatches are resolved by the creation of energy pathways that allow transfers to take place between producers and consumers.
• Coal - there is still significant global trade in coal. Three of the largest coal producers (China, India and the USA) also import coal. Australia and Indonesia export large quanities of coal
• Oil - the Middle East is clearly the number one global producer; there are flows from here to Asia, Europe and the USA. There is only one energy pathway from Russia, and that is to Europe
• Gas - gas flows occur in two different ways: either directly through pipelines, or converted into a liquid form (LNG) and moved by tanker ships. The former are mostly used for the export of Russian gas to Europe, while Middle Eastern gas is largely delivered by sea. 

Unconventional fossil fuels:

• Tar sands - Canada is a major exporter
• Oil shale - little exploitation as yet
• Shale gas - exploitation requires controversial fracking; USA is leading producer/exporter
• Deepwater oil - technological advances in drilling are beginning to make this a viable source; Brazil is leading the way at the moment

• All of these resources have potential to help meet future energy needs. Because of the fairly wide distribution of reserves, they offer some countries, currently dependent on imported energy, the prospect of greater energy security. 
• However, they come with a number of serious costs:
• They are all fossil fuels, so their exploitation and 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
• Extraction threatens environmental damage (e.g. the scars of opencast mines and possible ground subsidence) and environmental risks (e.g. pollution of groundwater and oil spills). It is an unfortunate fact that a large proportion of the proven reserves of these fuels happen to occur in fragile environments, both on land and in the oceans.
• Removal of vegetation now means that areas that were once sinks for carbon are becoming sources

• 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.
• The main forms of renewable energy being harnessed today are hydro, wind, solar, geothermal and tidal.
• It is a simple fact of physical geography that not all countries have renewable energies to exploit. E.g. not all countries have coasts or 'hot rocks', or warm climates with long sunshine hours, or permanently flowing rivers or persistently strong winds.
• There are very few, if any, countries where renewables might completely replace all the energy currently derived from fossil fuels
• 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 - e.g. 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
• Most people suddenly go off the idea of using renewables when there is a proposal to construct a wind or solar farm close to where they live.
• 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.

• Another attraction is that nuclear waste can be reprocessed and reused, thereby making it a recyclable energy source.
• However, there are issues related to:
• Safety
• The disposal of highly toxic radioactive wate with an incredibly 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
• Increasing attention is now being paid to the growing of biofuel crops as a way of decreasing the consumption of fossil fuels. These energy crops include wheat, maize, grasses, soy beans and sugar cane. 
• In the UK, the two main crops are oilseed **** and sugar beet. Most are converted into ethanol or biodiesel and used mainly as a vehicle fuel
• However, a hectare of space used to grow energy crops is a hectare less for growing much-needed food in a hungry world. 

Carbon capture and storage

• CCS involves 'capturing' the carbon dioxide released by the burning of fossil fuels and burying it deep underground. 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 being used quite widely, either at the point of production or at energy facilities from which gas is distributed to consumers.
• 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

Hydrogen fuel cells

• 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.
• Fuel cells are a promising technology for use as: a source of heat and electricity for buildings, a power source for electric vehicles.

• 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
• There seems to be a fair measure of certainty about the role it is just beginning to play in the context of transport.

HOW ARE THE CARBON AND WATER CYCLES LINKED TO THE GLOBAL CLIMATE SYSTEM?

Deforestation:

• 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
• The main driver of deforestation is the increasing demand for commodity production
• Half of all current deforestation is for soy, palm oil, beef and paper production
• By 2015, 30% of all global forest cover has been completely cleared
• Approx 13 million hectares are deforested annually

Afforestation:

• Afforestation and reforestation is beneficial for CO2 sequestration but can also be controversial in its impacts on landscape character as well as on carbon, water and soil systems

Grassland conversion:

• Temperate grasslands have no trees and have a seasonal growth pattern related to a wide annual temperature range.
• Tropical grassland or savannah 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 growth 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.

Ocean acidification:

• The world’s oceans are a major carbon sink – they have absorbed about 30% of the CO2 produced as a result of human activities since 1800, and about 50% of the CO2 produced by burning fossil fuels.

• For the past 300 million years, up to the early nineteenth century, the average oceanic pH was 8.2 but this had dropped to 8.1 by 2015.
• So since the Industrial Revolution began, the pH of surface seawater has decreased by 0.1. As this is a logarithmic scale this is about a 30% drop.
• By the end of the twenty-first century, the additional decrease in surface oceanic pH may be between 0.06 and 0.32.
• 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
• Coral reefs globally already show bleaching from warming temperatures.
• 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 allwoing attack from bioerosion 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-21st century if current levels of carbon emissions continue.

Climate change:

• 2015 was an exceptional year for climate change: it was the first full year to exceed the key benchmark for global warming of 1 degree 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
• 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

• 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
• Warming by 2 degrees could lead to 5% 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.
• 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.

• The UN has described the world's forests as 'fundamental' to human well-being and survival. Over 1.6 billion people depend on forests and over 90% of these are the poorest in societies.
• Societies reach a tipping point where exploitation changes to more protection.

• Factors affecting the timing of this attitudinal change are:
• The wealth of countries
• The rising knowledge of the role the environment plays in human well-being
• The aid given to poorer nations to help choices over exploitation
• The political systems and enforcement of environmental laws
• The participation of locals
• The power of TNCs
• 13% of forests - 524 million hectares - are now classed as 'conserved'. Brazil and the USA have the largest National Parks and Forest Reserves.
• Protective legislation has been combined with a greater involvement of local communities in planning and in developing policies, which is critical for long-term successful reductions in forest loss.
• Forest product extraction technology is improving, and carbon sequestration projects are increasing.
• Global warming is increasing temperatures globally, and since warmer air effects evaporation and stores more water, the amount of water in the atmosphere will increase. As a result, rain dropped during individual storms can increase, resulting in flash floods.

• Earth's cryosphere has already been affected by global warming. Over the last 20 years the Antarctic and Greenland ice sheets have been losing mass; most glaciers have continued to shrink, and Arctic sea ice and northern hemisphere spring snow cover have continued to decrease in extent and thickness.
• In the past few decades average Arctic temperatures have risen twice as fast as global averages.
• There are huge implications for ocean currents, air circulation, sea level rise and floding beyond the region.
• As a net sink, the Arctic stores far more carbon than any other region. In the short term an increase in CO2 uptake is predicted, but with further sea-ice loss, increases in marine plants such as phytoplankton may cause a limited net increase in the uptake of CO2 by Arctic surface waters. In the long term, a net outward flux of carbon is expected because of rivers bringing carbon from melted permafrost stores, and loss of methane hydrate from destabilised sea floor deposits stored for thousands of years. 
• Carbon uptake by terrestrial plants is increasing because of longer growing seasons and also the slow northward migration of boreal forests.
• There is a high risk of irreversible feedback, called runaway global warming. 

Loss of Arctic albedo:

• albedo is a measure of how sunlight is reflected away from the Earth's surface.
  
• Ice has a high reflectivity index, so a reduction in the amount of sea ice may create a positive feedback loop: melting allows more heat absorption, causing more melting. 
• Loss of reflective abledo is from:
• Less summer sea ice
• The replacement of (lighter) tundra with (darker) forests as they advance north with improving temperatures from climate shift
• Black carbon pollution on snow adds to heat absorption and melting

Carbon CO2 feedbacks

• Carbon emissons will outpace uptake as warming continues:
• Increased CO2 emissions from tundra soils
• Forest growth will absorb more of the Sun's energy, accelerating climate change
• Methane hydrates are found in permafrost and ocean sediments in shallow water. They store large amounts of carbon but destabilise after thawing and will add to greenhouse gases; CH4 is 25x more powerful a greenhouse gas than CO2

• Climate change is affecting ocean temperatures, the supply of nutrients, ocean chemistry, food chains, wind systems, ocean currents and extreme events such as cyclones.
• The changes may be categorised under: bleaching, acidification, rising sea levels and loss of sea ice.
• These changes then affect the distribution, abundance, breeding cycles and migrations of the marine plants and animals that millions of people directly or indirectly rely on for food and income.
• The importance of oceanic 'health':
• All countries, even landlocked places, eat and either sell or buy fish and shellfish. The marine fishing industry is now globalised with a high level of trade
• Fishing supports 500 million people, 90% of whom are in developing countries
• Fish is the cultural choice of many wealthier countries, e.g. Iceland and Japan but an absolute necessity for well-being in poorer countries. Fish provides 16% of the annual protein consumption for 3 billion people, and is the main source of cheap protein for over 1 billion people
• Millions of small scale fishing families depend on seafood for income as well as food; 6% of GDP is from fish 
• Countries that depend on exports of their fish resources, e.g. China and Thailand, will be affected by depleted and stunted stocks

• Only nations with large industrialised fishing fleets, e.g. UK or Japan, will be able to follow fish that are able to shift their location to adapt to ocean warming
• Many nations benefit from, and even rely on, tourism associated with coral reefs and their abundant marine life. In the Maldives 220,000 people are reliant on their coral atolls, which attract an annual influx of 1 million tourists
• Coral reefs also offer another 'service': over 200 million people live in coastal areas protected from waves by fringing reefs, e.g. Hawaii

• Key factors driving anthropogenic greenhouse gas emissions:
• Demographic rising population
• Cultural, Lifestyle, Ideology, Attitudes, Globalisation of consumerism - civil wars and terrorist threats increase the need for internal energy supplies
• Political, Governance, Climate change policy
• Economic, Industrial structure, Energy needs, Technology - increased globalisation and movement of goods and people globally generates more demand on resources and creates greater carbon emissions

• How much we will need to adapt to our changing climate depends on how much more the Earth's atmosphere warms.
• There are a range of hard and soft strategies and climate change adaption strategies. 
• Most need a strong lead by governments. This is possible in stable political regimes, although democracies may encounter more delays than more authoritarian-led countries, because of public debate and changes in policy following elections.
• Times of economic austerity may make it more diffiicult to fund new schemes or impose emission limits on struggling industries.
• Mitigation - involves the reduction or prevention of GHG emissions by new technologies and low-carbon energies, becoming more energy efficient, or changing attitudes and behaviour