Topic1a7 - Changes to the carbon cycle

Physical factors that affect the carbon cycle

Geological time scales

Volcanic activity

Weather and climate

Human factors affecting the carbon cycle

Hydrocarbon extraction and burning

Farming practices

Deforestation and landuse changes

How do wildfires affect the carbon cycle

They directly emit 15% of the carbon in the forest into the atmosphere. Fires are getting more frequent due to human activity which leads to a net release of carbon into the atmosphere. This is because there are less older trees which are carbon sinks and more new trees. 

What is the role of wildfires and what carbon stores do they change

They are a transfer and take solid, organic carbon from the biosphere to the atmosphere and lithosphere as gas that is inorganic. It does this through combustion

How do volcanoes affect the carbon cycle

They do not have a significant effect on greenhouse gases or enhanced global warming. The emissions are countered by sulfur dioxide which reflect solar radiation back into space. Recent volcanic events have released less than 1% of the CO2 released by human activity

What is the role of volcanoes and what carbon stores do they change

They are a transfer. Transfers solid carbon in the lithosphere(mantle) to the atmosphere as a gas through subduction and combustion. Volcanoes are physically induced changes that are so small they are insignificant over geological timescales because they remain relatively balanced.

How has human activity influenced carbon changes

Fossil fuels get burnt which releases CO2 that was otherwise locked away for millenia. It has a significant effect on the balance of gases in the atmosphere. Cement production by heating limestone also releases lots of CO2.

What is the role of human changes and what carbon stores do they change

They are a transfer from the lithosphere(fossil fuels) as inorganic carbon to the atmosphere as a gas. It is done through the process of combustion

What has been the trend of anthropogenic released CO2

Slowly increased from 1750 then rapid increase from 1850 when the USA started to industrialise. In 1950 there was global industrial revolution post world wars

How has farming influenced carbon changes

Ploughing in arable farming leads to increased CO2 emissions. Beef and dairy are the largest source of agricultural carbon emissions. Livestock and tractors release lots of greenhouse gases such as carbon dioxide and methane. It makes up 1/3 of farming emissions. Population increase also increases food demand so more livestock farming is needed which releases more greenhouse gases

What is the role of farming and how has it changed carbon stores

It transfers carbon from the lithosphere (soil) and biosphere to the atmosphere through ploughing and combustion.

How has deforestation caused changes in the carbon cycle

The world is now 50% urban and still increasing. urban areas have considerable releases of carbon. The emissions come from transport, industry and domestic use, cement production. North America has the most emissions per capita.

What are the negatives of ocean acidification

More acidic oceans means carbonic acid reacts with carbonate ions so there is less carbonate available for coral and other species to produce shells. This will result in significant reef loss.

What are the positives of ocean acidification

More acid in oceans means easier to dissolve calcium carbonate rocks which releases carbonate ions which increases the oceans ability to absorb CO2.

How does melting sea ice create a positive feedback of warming

Ice at the poles has high ALBEDO (most of the suns radiation is reflected) so if that melts there is more insolation (exposure to suns rays) of oceans so they warm up. This will then melt more sea ice in a repetitive process.

How would there be a reduction in ocean salinity

Higher rates of precipitation will cause more fresh water in oceans. So will higher temperatures melting ice sheets and glaciers. More fresh water in oceans can cause slowing down of large scale oceanic circulation in the North East Atlantic. This could potentially stop the North Atlantic drift and lead to Western Europe getting colder.