The carbon cycle - the carbon budget

carbon budget

amount of carbon gained and lost through natural or human processes. Involves transfer of carbon through different stores and balance between inputs and outputs. can be on a local or global scale

how does the carbon budget change on a global scale

small fluctuations but remains relatively stable - human activity disrupting this balance.

what does the carbon budget enable us to understand

how human and natural CO2 emissions are contributing to changes in earth’s environment

effect of changing carbon budget on the land: soil

carbon cycle responsible for soil formation - carbon from organic matter releases nutrients and provides soil structure needed for plant growth

effect of changing carbon budget on the land: how do warming temperatures effect permafrost

permafrost stores carbon on land. Temperature increases causes melting which restart the decay of organic matter, releasing carbon into atmosphere - causes positive feedback loop

what percentage of earth’s surface is covered by permafrost

22%

what is permafrost

subsurface layer of soil that’s frozen for two or more consecutive years

what temperature increased would result if 10% of permafrost in the northern hemisphere thawed

0.7C by 2100

impact on land: photosynthesis

negative feedback - carbon in soil essential for plant growth. More CO2 available leads to more photosynthesis and plant growth (carbon fertilisation). more plant growth means more storage of Carbon in biosphere.

impact of changing carbon budget on ocean: what is the second largest store and how does it impact phytoplankton?

ocean second largest store of carbon. carbon cycle impacts proliferation of phytoplankton - a basic food source for many marine organisms

impact of changing carbon budget on ocean: how does it make the ocean more acidic (ocean acidification)

30% of released CO2 diffused into the ocean through direct chemical exchange creating carbonic acid making oceans more acidic

2 impacts of lower pH in ocean

damage to coral reefs which provide food and habitat for marine species which are relied on by around 500 million people for food - less food security.

dissolve shells of marine species

effect of lost coral reefs from ocean acidification on coastal communities

less protection from storm surges

what did ocean acidification lead to in the USA in 2007 and what affect did this have

loss of millions of oyster farms - affected millions of coastal communities and cost millions of dollars in lost sales

impact of changing carbon budget on ocean: melting ice positive feedback loop

ice with high albedo effect replaced by water with low albedo effect meaning it absorbs more sunlight amplifying the warming

3 impacts of changing carbon budget on ocean: melting ice

sea ice provides habitat for algae - loss of algae will effect food chain

seals and polar bear lose habitat as can’t travel on the ice

sea level rise

how much has sea level risen since 1990’s

3.5mm

2 causes of sea level rise

melting terrestrial ice, thermal expansion

what is thermal expansion

when water heats up its expands and so has a greater volume and takes up more space

if earth continues to warm how much are sea levels expected to rise by 2100

up to 2m

why does melting of terrestrial ice occur and how does this cause sea level rise

warmer temperatures mean increased rate of ice melting in summer and reduced snowfall in the shorter winters. This imbalance results in a net gain in fresh water entering the ocean against evaporation from the ocean.

impacts of changing carbon budget on ocean: ocean salinity

decrease in salinity of deep North Atlantic - likely to be caused by higher temperature and more precipitation. Precipitation leads to higher river run-off that reach the sea. Higher temperatures cause melting of the Greenland ice sheet and many alpine glaciers - leads to increase in freshwater entering the ocean

what had decreases ocean salinity been linked to in the North East Atlantic

slowing down of the large scale oceanic circulation

impacts of changing carbon budget on ocean: how does ocean warming impact phytoplankton

warmer oceans caused - decrease in phytoplankton numbers (need cool, nutrient-rich waters) - could limit oceans ability to take carbon from the atmosphere through the biological carbon pump - makes ocean a less effective carbon sink.

CO2 needed for plant and phytoplankton growth - increase in CO2 could lead to increase growth

how does ocean warming impact coral reefs

warming kills symbiotic algae which coral reefs need to grow - leads to bleaching and death of coral

impact of climate change on ocean currents

Thermohaline circulation currents disrupted e.g. North Atlantic drift may slow due to ice caps melting, giving more freshwater into the ocean - less warm water is drawn north -could lead to colder temperatures in western Europe.

how does an increase in freshwater reduce the flow of warm water to the north

freshwater less dense than saltwater leading to a less dense surface layer that doesn’t sink as readily. this reduced sinking of dense salty water weakens to downwards part of the circulation which can reduce the flow of warm surface water north.

what does the Thermohaline circulation help regulate

global temperature

Impact of the changing carbon budget on the atmosphere: Increasing atmospheric CO2

global climate will become warmer

why is atmospheric CO2 important

controls global temperature

How does CO2 help regulate temperature

Carbon dioxide, methane and halocarbons are greenhouse gases that absorb a wide range of energy - including infrared energy (heat) emitted by the earth and then re-emit it

where will temperature rise be greatest (spatial variation)

Poles 10C

Impact of changing carbo budget on the atmosphere: what is radiative forcing

the amount the earth’s energy is out of balance

how is the earth’s energy balance (radiative forcing) determined

energy constantly flowing from atmosphere in form of sunlight. 30% sunlight reflected back into space and the rest is absorbed by the planet. some of this absorbed energy is radiated back into the colder surroundings as infrared energy - if the balance between incoming and outcoming energy is not equal warming or cooling can occur

why has radiative forcing increased

greenhouse gas emissions and changing albedo due to land use changes

why is measuring radiative forcing difficult

other impacting factors like natural changes in incoming solar radiation

Impact of changing carbo budget on the atmosphere: how does it cause more extreme weather events

higher greenhouse gas concentration - higher sea surface temp - increase in evaporation - increase in water vapour in atmosphere - more intense rainfall