Unit 2 - Global Climate

why is kiribati spelled like that? (is it spelled or spelt?)

Radiation

the emission of electromagnetic waves such as X-rays, short waves and long waves

convection

the transfer of heat by the movement of a gas or liquid

Conduction

the transfer of heat by contact

Atmosphere

a mixture of gases that surround the earth:

Mainly nitrogen (78%), oxygen (20%), argon (0.9%) and trace gases (incl GHGs)

Greenhouse gases (water vapour, carbon dioxide, methane, NO2, ozone)

atmosphere structure

Exosphere, thermosphere, mesosphere, stratosphere, troposphere, ozone layer

Atmospheric stratification

structure of the atmosphere, divided into different layers

Atmospheric pressure

force per unit exerted on a surface by the weight of air above it, measured in kiloPascals (kPa) or millibars (mb)

Ozone layer function

reduces the amount of uv radiation that reaches the earth

Average atmospheric pressure at mean sea level (MSL)

1,013.25 millibars

origin of atmosphere

Formed 4.6 billion years ago from volcanoes’ gases and the beginnings of photosynthesis in early organisms

Snow albedo

up to 90% because of light colour and small crystalline particles that scatter light

Ice albedo

50-70% reflectivity because its darker than snow and has a reflective texture but less so than snow, albedo depends on colour of ice hence pollutants in ice

asphalt road albedo

~5% reflectivity, larger particles, darker colour

Sand albedo

30-50% reflectivity, dependent on colour e.g. red sand v yellow sand, red sand has lower albedo

Periglacial areas

seasonally low temperatures and permafrost

Periglacial environments contain

some 400–500 gigatonnes(Gt) of carbon stored as DOM → would oxidise and contribute to accelerated greenhouse effect if permafrost melted

 percentage of global soil carbon stored in periglacial soils

30–40 per cent

Effects of climate change on arctic region

•  increase in primary productivity 

• Lack of nutrients may limit productivity

• Nutrients expected to increase as dead organic matter in permafrost breaks down so probs not an issue

• release of carbon and methane

  • positive feedback

Permafrost

• Dead organic matter decomposes extremely slowly because of low temperatures

• Dense accumulation of carbon: oxidises when it melts

methane emissions because of permafrost melt

• About 25–40 megatonnes (Mt) of methane are released each year from melting permafrost

• A 4ºC temperature increase could lead to a 45–65 per cent increase in the release of methane

• if 10% of the permafrost were to thaw, it could release enough methane into the atmosphere to raise temperatures by an extra 0.7°C

The Arctic sea ice minimum

generally reached in generally reached during September and the maximum during March. However, the overall volume, thickness and extent have been declining for decades

Wave formation positive feedback

In 2012, five-metre waves were recorded in the Beaufort Sea

arctic region map

its literally a circle u can do this!

Impacts of sea ice decline

• More sea ice decline (lol)

• Methane emissions will increase because of the release of chlorine atoms from the sea

• May be associated with wet summers in europe due to weakened jet stream

• Correlations between extreme weather in the northern and mid-latitudes and the disappearance of ice

• Sea ice decline linked with increase in primary productivity in the bering sea due to phytoplankton blooms

• Adverse effects on polar bears: less time to hunt seal pups and must spend more time on land, diets less nutritious, reduced body size and reproductive success

Himalayan glaciers

• Retreating (wow I’m so shocked!)

• Unlikely to cause major water shortages in the near future because of monsoon system

• Other factors like population growth and groundwater depletion could have a serious impact on water availability

Gangotri glacier

• One of the largest glaciers in the himalayas

• Glacial retreat could alter stream-flow characteristics

• 30km long and 0.5-2.5km wide

  • Retreated ~900m  since 1990

Swiss glaciers

• Consequences of glacier retreat: changes in water balance, glacial lake outbursts, mudslides, debris slides

• Glaciated surface of swiss alps declined from 1800km^2 in 1850 to 1300km^2 in 1971 - ⅓ loss

If temperature increases by 3ºC

• 35% drop in crop yields across Africa and the Middle East

• 550 million more people could be exposed to hunger

If temperatures increase by 2ºC

• 200 million more people could be exposed to hunger

Agricultural land shift

viticulture (production of grapes for wine), production of corn and wheat will move towards poles, away from equator

Northward shift of wheat production in North America

• Decline in US grain belt

• Increase in Canada’s growing season and primary productivity

• Serious effects on US economy

Wheat yields in UK

prediction that north will increase by 30%, yields in south will decrease by 30%

water resource change and crop distribution

• Reduction of water resources will mean increase in difficulty of irrigation

• Change in crop types and distribution of different crops

Temperature increase of 2ºC

• 60 million more people in the african continent could be exposed to malaria

• Mosquitoes would be able to breed in areas previously too cool

• Tropical diseases will spread to higher latitudes

Increase in climate refugees 

• Kiribati, other islands in the South Pacific due to rising sea levels

• Kivalina, Alaska immigration due to rising sea levels

silver lining or arctic ice melt

Opening of sea routes for trade

Tourism likely to change

• Less winter tourism (rip thredbo) 

• More summer tourism in higher latitudes

• Currently popular areas may become less so due to reduction in water resources and resulting lack of economic viability

Bangladesh flooding vulnerability

20% of GDP and 65% of the labour force is involved in agriculture that is threatened by floods in low-lying areas, risk of food scarcity

low lying countries

buh bye!

climate migration (floods and droughts)

200 million people at risk of being driven from their homes by flood or drought by 2050

climate change affect on storms

an increase in storm activity such as more frequent and intense hurricanes (owing to more atmospheric energy)

climate change and rainfall

reduced rainfall over the USA, southern Europe and the Commonwealth of Independent States (Russia and the -stans) leading to widespread drought

climate change and water availability

up to 4 billion people suffering from water shortages if temperatures rise by 2°C