EQ3- How are the carbon + water cycles linked to the global climate system?

Reason for land conversion

Growing demand for fuel, food + other resources.

-biosphere sequesters ¼ of fossil fuel carbon emissions per year, slowing rate of global warming

Impact of deforestation

-soil health, water+carbon cycle

On soil health

rapid soil erosion leads to loss of nutrients- 400 tonnes per hectare per year

biomass loss due to reduced photosynthesis

On water cycle

↓ interception by vegetation so ↑ infiltration to soil

↑ erosion+soil runoff, increasing sediment eroded + transport to rivers

On water cycle

↑ carbon flux to atmosphere by burning+decomposing vegetation

↓ CO2 intake during photosynthesis

Impact of afforestation

Planting trees on land that has never had forest or has been without forest for a long time.

+block strong winds to prevent soil erosion

+intercept rainfall to prevent flooding+ ↑ infiltration

+act as large carbon store+ ↑ carbon sequestration

-commercial trees e.g. palm oil store less carbon, use more water and are prone to disease

-growing same species: less diverse insects for seed dispersal, disease can spread more easily

-space can be used to grow crops instead

Impact of conversion of grasslands to farming

-on soil health, carbon+water cycle

Soil health

fertilisers, chemicals pollute soil- soil degradation

Water cycle

biofuel crops need lots of water, so need irrigation which has significant impact on aquifers

cultivated soils are liable to erosion by runoff

Carbon cycle

initial removal of grassland releases CO2 from soils into atmosphere

annual ploughing enables soil bacteria to release CO2

Ocean acidification

Ocean becomes more acidic due to ↑ levels of CO2 dissolving into ocean water.

-exacerbated by warming temp, pollution, tropical storms

-acidity is 25% greater than pre-industrial times

Impact of ocean acidification

Risks crossing the critical threshold (point beyond which damages become irreversible) for health of coral reefs.

-fewer carbonate ions→ thinner, weaker shells/ skeletons→ more attacks from worms, sponges→ reef building collapses + dissolves

-corals shelter 25% marine species- these shelters disappear so risk of extinction

-loss on income from tourism+fishing industries

How does climate change ↑ frequency of drought?

Shifting climate belts- 2 degrees ↑ in temp may lead to 5% of Earth’s land area shifting to a new climate zone- ↑ of droughts

• GHG emissions cause temp to ↑ so more moisture evaporates

• warmer temps also ↑ evaporation from soil, which affects plants + reduce rainfall even more

• drier soils are less able to absorb rainwater, ↑ likelihood of flooding

Amazon droughts

• Amazon pumps 20bn tonnes of water into atmosphere each day

• rainfall has ↓ downwind of deforested areas leading to Sao Paulo water crisis

• has had droughts in 2005, 2010 + 2015

• feedback loop: more trees die→ less transpiration + enhanced greenhouse effect→ more likely for droughts to occur

Forest ecosystem services

Cultural services: spiritual (flower bathing), educational, aesthetic (waterfalls), recreational (tourism)

Provision of goods: food production, water, wood+fiber

Supporting services: nutrient cycling (trees drop leaves, minerals enrich soil..), soil formation (dead organic material drop from trees), primary production (convert sunlight to energy)

Regulating services: water purification (water passes via plants + remove of toxins), flood regulation, climate regulation (evapotranspiration causes more moisture- rainfall, removes CO2)

How does protection of forest stores change as a country develops?

Kuznets curve suggest that communities reach a tipping point where exploitation of forests changes to more protection.

Factors affecting change in attitude:

• wealth of a country

• increased knowledge of the role that the environment plays in our well-being

• power+influence of TNCs

• aid given to developing countries to reduce exploitation

• political systems + enforcement of environmental laws

UK- moving industry to other countries to reduce environmental degradation e.g. China

Kuznet’s curve example- Palm oil Indonesia

PRE-INDUSTRIAL: growing demand for palm oil led to increasing production for it-66M tonnes per year.

INDUSTRIAL: 2015-Indonesia is the world’s largest producer of palm oil with GHG emissions overtaking USA due to burning forest.

-Orangutan endangered due to loss of biodiversity + habitats, Sumatran tiger

POST-INDUSTRIAL: forest moratorium (ban/ suspension on an activity) declared aimed at reducing deforestation with $1bn of funding from Norway + UN- emissions fell by 2.5% in 2yrs.

-further reduce by 26% by 2020

What does forest protection in the long term require?

Requires:

1. protective legislation

   18% forests are currently classed as conserved

   Brazil + USA have the largest National Parks + Forest Reserves

2. community involvement in planning + developing policies

EXAMPLE: Players attitudes: Consumers join environmental pressure groups e.g. WWF + Greenpeace, and support their campaigns- money raised is used to fund.

-Greenpeace activists blockaded a palm oil refinery in Rotterdam

Impact of increased temp

• impacts evaporation rates + ↑ water in atmosphere

• impacts hydrological cycle: precipitation patterns, river regimes, water stores (cryosphere + drainage basin)

Impact of increased temp- Arctic case study

• plays vital role as sea ice regulates evaporation + precipitation

Cryosphere impact

Antarctica+Greenland ice sheets have lost mass + glaciers are shrinking

Arctic sea ice + spring snow cover in N. hemisphere continue to ↓ in thickness+extent

Acts as a early warning system

Arctic temp has risen 2x as fast as global avg

loss of ice e.g. NW passage can be navigated in summer

loss of albedo- being replaced by tundra

Implications of ocean threats for humans

Threats to ocean: bleaching, acidification, rising sea levels, loss of sea ice.

Uncertainty about natural factors (terrestrial + oceanic carbon stores)

• role of carbon sinks + their capacity to cope with changes

• possible feedback mechanisms e.g. carbon released from peatlands + permafrost

• tipping points associated with forest dieback + reversal of thermohaline circulation

Uncertainty about human factors

• future rates of global economic + pop. growth

• planned reduction in global carbon emissions

• exploitation of renewable energy sources

What is an adaptation strategy?

Strategies which include any passive, reactive or anticipatory action to adjust to a changing climate.

4 adaptation strategies to changed climate

1. Water conservation

2. Resilient agricultural systems

3. Land use planning + flood-risk management

4. Solar radiation management

Pros + cons of Water conservation

+Reduces erosion+floods

+Reduces pesticides + fertilisers runoff, resulting in cleaner lakes e.g. Israel has a desert climate- recycles 85% of wastewater

-High cost of storage (collecting rainwater)

-May not be able to catch+hold, leading to some entering drains+rivers

Pros + cons of Resilient agricultural systems

+Generate healthier soils- help CO2 sequestration + water storage- reduce ploughing, etc e.g. study regions in Spain + Italy

-more expensive tech

-Seeds+breeds unavailable to subsistence farmers without aid

Pros + cons of Land use planning + flood-risk management

+Ensure efficient use of limited land resources, reducing urban sprawl

+Encourages maintenance of natural landscapes that can absorb floodwater- forests, wetlands

-Land use restrictions limit economic development

-Hard defences against floods are expensive+ruin landscapes

Pros + cons of Solar radiation management

+Globally cause cooler temps, helping mitigate heat stress on crops+improving agricultural yields

-lead to variations in precipitation + temp, potentially harming vulnerable ecosystems while benefitting others

What is a mitigation strategy?

Involve the reduction or prevention of GHG emissions by using new technologies, renewable or low-carbon energy sources + becoming more energy efficient through changing attitudes + behaviours.

5 mitigation strategies to a changed climate

1. Carbon taxation

2. Renewable switching

3. Energy efficiency

4. Afforestation

5. Carbon capture + storage

Pros+cons of Carbon taxation

+Economic incentive for businesses to reduce carbon footprint, lowering emissions.

e.g. lower road taxes for low-carbon cars scrapped in 2015

-Harms low income households who spend larger portion of income on energy costs, which increases due to the tax.

Pros+cons of Renewable switching

+Reduces GHG emissions

e.g. Climate Change Levy to encourage investment in renewable energy was cut in 2015

-Don’t provide consistent power

Pros+cons of Energy efficiency

+Reduces energy consumption, leading to cost saving + cutting emissions.

-Initial investment in infrastructure, can be expensive, acting as a barrier.

Pros+cons of Afforestation

+Help regulate water flow + water resources (storm flow, erosion control)

e.g. The big Tree Plant campaign encourages communities to plant 1M trees

-monoculture that lacks plant diversity + reduces the no. of available habitat types for forest inhabitants

Pros+cons of Carbon capture + storage

+captures CO2 from industrial processes, preventing it from entering atmosphere. e.g. Canada’s boundary dam

-tech is costly to implement + deploy at wider scale, leaving uncertainty on impact on global emissions.