Climate change

  • Created by: Georgie
  • Created on: 12-03-18 13:54

Methods to reconstruct past climates

Sea-floor sediment- fossil shells from foraminifera (tiny sea creatures) can be used. Chemical composition indicates sea temperature in which they're formed. Fossils with heavier isotopes formed in warmer conditions 

Ice-cores- from the polar region contains tiny bubbles of air (records of the gaseous composition of the atmosphere in the past). scientists measure relative frequency of oxygen and hydrogen atoms with isotopes. Colder the climate, the lower the frequency of isotopes 

Lake sediments- pollen grains, spores, diatoms, and varves can be used.

  • Pollen analysis identifies past vegetation types and from this interferes with paleoclimatic conditions. Pollen diagrams show the number of identified types in different sediment layers. 
  • Diatoms- single-celled algae found in lakes, their cell walls are made from silica. Past climate recorded in their shells
  • Varves- tiny sediment layers comprising of light (coarse sediment, indicate high energy, meltwater run-off in spring/summer) and dark bands (fine sediment, deposition during winter)

Tree rings- annule growth, vary in width depending on temp and moisture. warmer = thicker

Fossils- plants/animals need specific conditions to thrive. i.e. coral reefs are sensitive to temp, water depth, and sunlight. Animals are more adaptive

1 of 43

Long term transition to colder global climate

Greenhouse- atmospheric CO2 concentrations, global temp, and sea level are high

Icehouse- atmospheric CO2 concentrations, global temp, and sea level are low.large parts of the continent

  • Glacial and interglacial periods in icehouse conditions
  • Most recent, Pleistocene, lasted 1 million years

100 million years ago (mid-Cretaceous period) average global temp we 6 to 8 degrees higher than today. Sub-tropical conditions extended from Antartica to Alaska and there were no polar ice caps. This lasted for 10 million years and coincided with CO2 levels being 5x higher than today

55 million years ago- Pleistocene-Eocene thermal maximum (avg. global temp = 23 degrees)

35 million years ago- Oligocene period (rapid transition to colder conditions, this was related to major reductions in CO2

2 of 43

Glaciation of Antarctica

  • Largest glacial system on the plant
  • 26.5 million cubic km of ic
  • 40 million years ago the continent experienced sub-tropical conditions (Palaeocene-Eocene thermal maximum)
  • The descent of Antartica into permanent icehouse state occurred 35 million years ago (Oligocene period)

Decent into Icehouse state occurred because...

  • CO2 levels dropped abruptly from 1100ppm to 700ppm 
  • continental drift (movement of Antarctica towards south pole isolated the continent, allowing Arctic Circumpolar current to insulate Antarctica from warmer northern water)
  • The growth of south sandwich islands' (chain of small islands) submerged volcanic arc disrupted deep water ocean currents around Antarctica, isolating from warmer water
3 of 43

Quaternary glaciation

Last 2.6million years

  • Cyclic changes of climate (long periods of glacial interrupted by shorter periods of interglacial
  • Glacials last around 100,000 years, temperatures in NW Europe remained below zero
  • Interglacials last 10,000-15,000 years
  • past 450,000 years there's been 4 major glacial periods and 4 inter-glacial 

Most recent glacial, Devensian, reached its maximum around 20,000 years ago when approx. one-third of the continental surface was covered in ice or snow

Stadial (brief cold spell) returned for 1000 years 11,700 before present

4 of 43

The Holocene- Our present interglacial

It began at the last glacial, 11,700 years ago

Ice sheets and glaciers have shrunk and sea level has risen by over 100m

ice sheets have disappeared from the continental surface (exception of Greenland + Antarctica)

Their remnants only survive in high mountains e.g. Himalayas 

Fluctuations of warming and cooling- 6000 years ago temp was 1-2 degrees higher than today and an early medieval warm period occurred between 1100 and 1300. This was followed by a little ice age (1550-1850) when avg.global temp fell my 1 degrees

5 of 43

Milankovitch

  • Long-term climatic shifts such as glacial cycles are caused by astronomical events
  • affect the amount of solar radiation reaching the surface and it's spatial and temporal distribution 

obliquity (tilt of earth's axis)-

  • over 40,000 years, earth axial tilt (perpendicular to orbital plane) varies from 22 degrees to 24.5 degrees (current = 23.4)
  • tilt close to 22, seasonal temp differences are reduced. Thus snow and ice accumulation in winter doesn't melt in summer, allowing for glacial expansion
  • Increases reflection of incoming solar radiation and lowers temp even further

Eccentricity

  • Earth orbits sun in an elliptical path. Eccentricity varies from near circular to markedly elliptical over 96,000 and 413,000 years
  • With maximum eccentricity, differences in solar radiation receipt of around 30% occur between perihelion (eath closest to the sun) and aphelion

Precision of equinoxes

  • Earth gyrates on its axis, so perihelion changes all the time 
  • The shift occurs every 22,000 years due to the gravitational influence of the Moon and Jupiter which effects the season intensity
  • If perihelion occurs during northern hemisphere's winter then it will be warmer  and summer cooler, so snow and ice will expand
6 of 43

Volcanic Eruptions

Eruptions pump sulphur dioxide and ash into the stratosphere

Sulpher dioxide has a cooling effect

Converted to sulphuric acid in the atmosphere, which forms sulphate aerosols 

Sulphate aerosols reflect solar radiation back into space and lower temp into the troposphere

e.g. Mount Pinatubo (1991), injected 20million tonnes of SO2 into the stratosphere and cooled the earth by 13 degrees Celsius over 3 years

7 of 43

Plate tectonics and continental drift

Driven by plate tectonics and seafloor spreading 

As continents started moving apart ocean currents formed causing climate change, as ocean currents transfer heat around

During enhanced tectonic activity and seafloor spreading elevated levels of carbon dioxide emissions may increase GHG

e.g. 

Movement of Antarctica towards south pole isolated the continent, allowing Arctic Circumpolar current to insulate Antarctica from warmer northern water

8 of 43

Ocean Circulation

Transfer warm water from tropics to poles

5 million years ago the formation of Isthmus and Panama, which joined N and S American continents and closed the 'gateway' between Pacific and Atlantic Oceans 

This event intensified the gulf stream, conveying warm surface water from the Carribean to the North Atlantic 

This increased evaporation and precipitation, prevailing westerly winds deposited more precipitation in N Atlantic, Europe and Siberia diluting salinity of N Atlantic and the Arctic

Reduced salinity weakens downwelling and thus  shuts down the thermohaline circulation

this led to the expansion of sea ice in North Atlantic and Arctic, thus increasing the reflection of solar radiation and insulation of warmer ocean waters beneath sea ice

9 of 43

Natural Green House Gases

Icehouse corresponds to lower levels of CO2 

During past 800,000 years, CO2 has fluctuated between 170ppm and 300ppm 

CO2 is removed from the atmosphere by plate tectonics forming fold mountains which increases rainfall, erosion and chemical weathering by rainwater charged with CO2. Thus large volumes of CO2 are removed from the atmosphere and transferred to storage in carbonate sediments in oceans. This stimulates vast blooms of phytoplankton, which extract CO2 from the atmosphere and when they die CO2 is trapped in the deep ocean sediments

10 of 43

Sunspot activity

Sunspot- spot occurring on the suns surface, they are cooler than the surrounding areas

Sun's output varies over time. Measured in millennia or century

Solar output follows an 11-year cycle. However difference between max and min sunspot activity it 0.1%

During the little ice ace (Maunder Minimum) sunspot activity fell to almost zero

11 of 43

Evidence of a warming world

Increase global temp

  • The rise of global land and ocean temp
  • Every year since 1977 has recorded above-average June temperatures
  • The steep rise of global temperatures in the 21st century (2014) was the warmest year for mean global land and ocean temperatures since records began, with land and ocean temp 1 degrees and 0.57 degrees above average
12 of 43

Shrinking valley glaciers and ice sheets

  • retreated or disappeared in some areas
  • The trend is set to continue in the alps and valley glaciers may shrink by 80-96% by the end of the century 
  • Between 1961 and 2005 the thickness of small glaciers worldwide decreased on average by 12m, the equivalent of 9000km3 of water
  • Antarctica and Greenland ice sheets contain 97% of global ice store
  • Present-day melting of polar ice sheets adds approximately 1mm to sea level every year due to..

Warming of the atmosphere, which melts the ice surface

warming, which produces meltwater that penetrates the ice and increases the velocity of glacier flow 

ocean warming, accelerating accelerating melting of ice sheets in coastal areas

13 of 43

Rising sea level

  • Since 1900 the average rise has been 1-2.5mm/year
  • Recent evidence from satellite suggests sea level is currently rising at a faster rate- 3mm/year
  • Sea level rise because...

Thermal expansion of the oceans as the climate warms

Melting of land-based ice sheets and glaciers

14 of 43

Increasing atmospheric water vapour

  • Water vapour is the most important GHG. It traps huge amounts of energy radiated from the Earth's surface and creates a natural greenhouse effect 
  • Amount of water vapor in the atmosphere is directly related to temp and rates of evaporation
  • warmer world = more atmospheric moisture
  • Every 1-degree increase in temp caused by enhanced CO2 levels, rising levels of water vapour will double the warming 
  • Positive feedback- more water vapour intensifies greenhouse effect- more evaporation - more warming....
15 of 43

Decreasing snow cover and sea ice

  • Satellite measurements reveal a decline in spring snow cover of 2% per decade since 1966 in the northern hemisphere
  • Snow has a high albedo, reflecting 70-80% of incoming solar radiation compared to 10-15% for soil and veg
  • Diminishing snow cover increases absorption of solar radiation
  • Suns energy warms the ground and air temp rises
  • In winter Arctic sea ice covers 20million km2, in summer this shrinks to 5million km2
  • Sea ice since 1979 has declined dramatically. In summer the area is decreasing on avg. 8% per decade and 3-4% in winter
16 of 43

Why anthropogenic GHG has increased since pre indu

  • GHG warm the earth and its atmosphere by intercepting outgoing, terrestrial radiation and radiating it back to the surface and atmosphere
  • Before 1800 concentration was 280ppm. In 2015 is passed 400ppm, 40% increase in 200 years

why?

  • Rise in demand for electricity due to industrialization and technological advances
  • global population growth from 1 billion in 1800 to 7.4 billion in 2015
  • land use change e.g. deforestation (5.2million ha between 2000 and 2010), drainage of wetlands and urbanisation.

Today 40% of the planet's land surface is used for ag  compared with 7% in 1700

  • continued high dependency on fossil fuels- today it supplies 87% of the world's energy and 2/3 of GHG emissions come from the burning of fossil fuels

Expansion of the world economy between 1990 and 2012, stimulated by globalisation and the growth of EDC (especially China) increased the consumption of fossil fuels and led to a 51% rise in CO2 emissions

17 of 43

Balance of anthropogenic emissions around the word

  • Between 1850 and 1960 most GHG emissions came from the industrialised economies of North America and Europe. USA's emissions since 1850 are almost equal to China, Russia, Germany, and UK combined
  • Since 1960's emissions from Asia, particularly China have increased significantly. Those of N America and Europe have stabilised and some fallen e.g. Germany and the UK 
  • Global emissions remain uneven but  concentrated with the top ten countries  accounting for 80% of emissions
  • USA, Aus, Germany, and UK still account for the highest CO2 emissions (the USA and AUS emit 17 tonnes/year per person)
  • When emissions of methane from land-use-change is added as a GHG, Brazil and Indonesia enter the ranking in 3rd and 4th place after China and USA due to deforestation in Amazonia and Indo-Malaysia
18 of 43

How additional GHG being added to the atmosphere w

GHG = water vapour, CO2, CH4 occur naturally in the atmosphere

They allow shortwave radiation from the sun but absorb long-wave radiation, heating earth surface

Without the natural greenhouse effect, the average temperature at the Earth's surface would be around 34 degrees c lower than today

Increased since 19th century GHG have increased by 1/3 

The enhanced  greenhouse effect is the impact on the climate from additional heat retained as a result of increased CO2 and other GHGs that humans have emitted into Earth's atmosphere since the Industrial Revolution 

19 of 43

How humans influence the global mean energy balan

  • Earths atmosphere is a closed system, with inputs of solar radiation and outputs of terrestrial radiation. When inputs and outputs equal the system is stable
  • 45%  of incoming solar radiation reaches and warms the earths surface (1/3 reflected from couds, 1/5 absorbed by water droplets, CO2, ozone  and dust in the atmosphere, and a small amount is reflected from the surface i.e. snow)
  • Of the out-going radiation, two-thirds are lost in space  and the rest is absorbed by GHG's
  • 84% of heat radiation leaving the earths surface returns
  • Human activities in the past 200 years have upset the balance
  • Increasing amounts of GHG absorb terrestrial radiation, which returns as back radiation
  • Rising global temperatures increase evopouration, transfer more latent heat to the atmosphere and increase concentration of water vapour
  • Rising global temps melt snow, glaciers and sea ice in the Arctic, reducing  albedo and reflection of incoming solar radiation, adding heat to earth-atmosphere systrm
20 of 43

Historical Background to the global warming debate

  • 1842- GH effect was discovered
  • 1862- suggested that CO2 and water vapour trapped heat escaping from the surface
  • 1896- a suggestion that CO2 absorbs longwave radiation and doubling it would increase temperatures by 5 degrees c 
  • 1938- global warming linked to fossil fuels
  • 1957- scientific progress ruled out the ability of oceans to absorb excess CO2 meaning it remains in the atmosphere for longer than originally thought
  • 1958- Proof that CO2 concentrations increased year  by year
  • 1970's- satellite imaging and computer modeling advanced the argument in favor of GW. Computer models revealed that human activity was the main driving force
  • 1988- Intergovernmental Panel on Climate Change (IPCC) was set up
  • 97% agree 

however

  • Dissenters argue that rising temp in the first half of the 20th century were due to increased solar output and exceptional volcanic activity- this has been undermined by the decrease of both of these but yet an increase in temp
21 of 43

Role of governmental organisations- UN

  • 1992 42 countries joined the UN Framework Convention on Climate Change (UNFCCC) to consider what action should be taken to limit global warming
  • Efforts of the UNFCCC culminated in the Kyoto Protocol 1997
  • 192 countries were party to the Kyoto Protocol through USA and China never ratified
  • First Koyoto period ended in 2012 (involved 37 countries who agreed to cut emissions by 5% below 1990 levels) and the second will run from 2013 to 2020 (ambitions to reduced by 18% by 2020)- Japan and Russia 
  • Koyoto recognised that AC's were primarily responsible over the past 150 years, therefore, placed a heavier burden on these to take action
  • International climate change conferences aim to achieve legally binding agreements to combat climate change. Priority to reduce GHG emissions and limit global temp increase to no more than 2 degrees c above the pre-industrial average
22 of 43

Role of governmental organisations- EU

  • Past 25 years it has compiled a comprehensive package of measures to reduce GHG emissions through its European Climate Change Programme (ECCP)
  • First ECCP was launched in 2000 and the second in 2005
  • Set targets for reducing GHG up to 2050- the aim is to transform EU into a low carbon economy
  • 2020- 20% GHG reduction, 20% of elec generated by renewables and 20% improvement in energy efficiency
  • Emissions Trading System (ETS)- Cap and trade- covers 45% of emissions from the EU 
  • Targets a 21% reduction in emissions from power stations, industry, and aviation by 2020 (compared with 2005)
  • National Emissions Reduction Targets covers the remaining 55%, mainly from ag, transport, and waste
23 of 43

UK policy

Climate Change Act (2008) commits the government to reduce emissions by 80% by 2050, compared with 1990 and to develop a more energy efficient low-carbon economy 

Strategy includes

  • Setting carbon budgets (5yr periods) as stepping stones towards 2050 target
  • Reducing demand for energy using domestic smart meters, promoting efficient and reduction from transport
  • Investment in low-carbon tec such as carbon capture storage and encouraging renewables
  • Carbon taxes to switch electricity generation from coal-fired power station to greener fuels. In 2014 there were 10 coal-fired power stations which were responsible for 1/5 of emissions

Introduced in 2003- taxed carbon emissions started at £16/tonne and expected to rise to £70/tonne by 2030 

24 of 43

India

Didn't ratify Kyoto- argued the rich countries should shoulder the cost of reducing emissions

Thus the USA didn't support Kyoto (biggest emitter at the time)- Gov said without China and India the protocol would be meaningless

India's case

  • its per capita energy consumption (1.7 tonnes) was below global 5 tonnes average
  • it prioritized alleviating poverty and expanding access to electricity 
  • High concentrations of CO2 were largely the result of industrialisation and economic growth of ACs over last 150years

Has its own National Action Plan on Climate Change but has decided to reduce emissions as a ratio of its GDP. Using this measure it targets 20-25% reduction by 2020 based on 2005 levels

NAPCC aims to improve energy efficiency and develop renewables especially solar

GHG emissions expected to be in the range of 4-7.3 billion tonnes by 2030 compared with 2.43 billion tonnes in 2010

25 of 43

Public image of climate change

TV, magazines, and newspapers influence public opinions

Most people don't read scientific journals and reports 

Right-leaning newspapers (The Times, Sunday Telegraph) are more likely to report sceptical (doubtful) opinions of climate change than left-leaning papers (The Guardian)

Some media organizations (BBC) have attempted to provide a balanced discussion and accommodate dissenting views, however, have been accused of false balance 

Strongest opponents to climate change have been energy industries (oil, gas, and mining). They see restrictions on consumption of fossil fuels as weakening to economic growth, creating unemployment and even as a political ploy to redistribute wealth. Some energy companies employ scientists to support their case

Media has weakened climate change arguments in the public mind by simplistic and sensational reporting 

26 of 43

Importance of the carbon cycle

Principle stores = ocean, atmosphere, carbonate rocks, soil and the biosphere 

Main pathways = photosynthesis, respiration, decomposition and chemical weathering

The carbon cycle is in a state of dynamic equilibrium 

The carbon cycle is important because...

  • All living organisms depend on it (fundamental building block for life)
  • Needed for photosynthesis 
  • Ocean sediment and carbonate rocks lock away sediment for millions of years helping maintain atmospheric CO2 levels conducive to life on the planet
  • Decomposition and oxidation recycle CO2, replenishing stores in the atmosphere for photosynthesis
  • CO2 and CH4 absorb longwave radiation from the Earth's surface and contributing to natural GH effect
27 of 43

Positive Feedback

Positive- amplifies change and increases disequilibrium 

e.g. 

  • GW intensifies evaporation - increased water vapour in the atmosphere - raises global temp - creating further evaporation
  • Melting glaciers, sea ice, and snow reduced albedo - more solar radiation absorbed - temperature increases - further melting 
  • Increased global temps cause trees to die -
28 of 43

Negative feedback

Restores balance in a system

  • Rising temps - tree lines advance polewards- more CO2 absorbed
  • higher evaporation/water vapour  increases cloud cover - increase albedo - lower temps
  • Burning fossil fuels releases aerosols of smoke, dust, and sulfur - reflect incoming solar radiation back into space - slows global temps (global dimming)
29 of 43

Future emissions scenarios and their impacts

Forecasting the future is extremely difficult because of the complex nature of the earth's anthroprogenic system and uncertainties about future GHG emissions 

The IPCC provided a range of forecasts...

  • GHG emissions peak 2010-2020 and decline thereafter
  • GHG emissions peak around 2040 then decline
  • GHG emissions peak around 2080 and then decline 

Temperature increases range from 0.3 degrees c to 4.8 degrees c. However a mean global temp rise of around 2 degrees in most likely 

Mean global sea level change

  • the result of thermal expansion of oceans due to warming and loss of ice 
  • Between 1901 and 1990 mean global sea level rose by 1.5mm/year
  • Between 1990 and 2000 MGSL rose by 3mm/year
  • Suggested min rise of 0.28m and a max of 0.98m by the end of the century
30 of 43

Vulnerability of people to climate change

Their vulnerability is affected by where they live and their ability to cope. Those at greater risk are concentrated in poorest countries- fewer entitlements to protect themselves and family from natural hazards and to cope with the loss of crops, property and increase of food prices

Elderly, young and chronically ill are least likely to cope with the effects e.g. 2003 European heatwaves killed 35,000 (majority over 75 yrs)

Rural communities in the developing world, rely on subsistence farming, they're extremely vulnerable. Majority depend on direct rainfall for successful cultivation of crops/raising livestock

Climate change will make rainfall more erratic and floods/droughts will become more frequent e.g. severe land degradation and desertification in the Sahel, northern Africa

Farming regions affected by drier conditions in the future include areas such as Prairies, N America, and Pampas, Argentina. Decline leads to food shortage of wheat and maize

98% of glaciers are retreating atm and thus regions relying on meltwater for irrigation will experience water shortage in the future

Low-lying coastal regions in tropics/subtropic regions are susceptible to flooding by powerful storms and rising sea level e.g. Bangladesh- storm surge (1991) killed 130,000 compared to USA in 2005 where 1400 were killed

Urban populations are at risk of heatwaves and soaring summer temps

31 of 43

Vulnerability of environment to climate change

Tundra- Rising temp melts permafrost, disrupting vegetation, creating extensive thaw lakes and wetlands, and initiating a mass movement 

Mountains- Glaciers will retreat in warmer conditions. Thawing and glacier retreat will make slopes less stable and trigger more frequent mass movement (e.g. landslides). The snow line will recede upslope and the winter snowpack will thin reducing meltwater into oceans

Hot, semi-arid environment- Rainy seasons will shorten and droughts will become more frequent and prolonged. With less vegetation cover and drier conditions, wind erosion (deflation) will increase and so will dust storms 

Rainforests- Amazon predicted to become drier and warmer by mid 21st century. As Increased deforestation causes water cycle to weaken, creating positive feedback and accelerating forest lost. 30-60% could become as dry as the Savanna grassland by the end of the century

Coasts- Higher sea levels and more powerful storms increase erosion on upland and lowland coasts. Shorelines will retreat inland. Environments at risk: saltmarshes, dunes, and mudflats

32 of 43

Implications of climate change for people and the-

Ecosystems- communities of plants, animals and other organisms and the physical environment. Within the ecosystem, organisms interact with each other and the environment through flows of energy and the cycle of nutrients

Marine ecosystems- Effected by rising sea level. Coral reefs are threatened by bleaching, in the last 30-40 years Indonesia has lost half its reefs to bleaching and in the Caribbean, it has reached 80%

Warming of Arctic ocean and melting of sea ice (crucial to mammals such as walrus- use it as a diving platform for foraging on the seabed and seals- use it to give birth and raise pups) have decimated ice algae, the base for the marine food chain. Disappearance of sea ice contributes to the projected 2/3 decline of the polar bear population by mid-century

Indigenous Inuit hunters- economy and culture depends on hunting marine animals, but thinning and melting of sea ice makes this dangerous and more open water means an increase in the number of killer whales

Uk, average sea surface temps have risen by 1.6 degrees c since 1980- this limits food supplies, growth rates and spawning for fish. Some cold-water species (cod) have moved N towards Iceland and warm water species have migrated to the UK

33 of 43

Implications of climate change for people and the-

Temp in the tundra is rising faster than any other ecosystem. At the permafrost thaws, wetland areas expand, attracting more migratory birds

Southern fringe of the tundra will lose their open aspect as the tree line advances N thus changes in habitat will occur which will affect indigenous plant and animal species

Cairngorms is a high-level plateau in NE Scotland, home to the Arctic hare. It is estimated that a 1-degree c rise in temp requires an uphill movement of 200-275m to maintain the same habitat. Even with this modest warming, scotland would lose 90% of its habitats and continued warming would result in the extinction of the Arctic hare

Phenology- changing the time of seasons, cause loss of synchronization between species: animals awaken from hibernation or start to breed before the emergence of resources

34 of 43

Implications of climate change for people and the

WHO forecasts an additional 250,000 deaths a year worldwide between 2030 and 2050 

Stimulate the transmission of vector-borne diseases. Dengue fever, from Aedes Mosquito, formally confined to the tropics and sub-tropics, is today found in 28US states. Between 1995 and 2005, 4000 cases were reported

Responsible for the spread Lymes disease 

Malaria- 800,000 deaths/yr is spread by Anopheles mosquitos. It's seasonal throughout tropical Africa but a warmer and wetter world could see it spread to Malaria-free areas such as Europe

High temp increases the risk of food contamination by salmonella and other bacteria causing food poisoning

Heavier rainfall increases flooding and the probability of water supplies being contaminated- multiplying the risk of diarrhea. droughts and floods also reduce food supply leading to malnutrition in LIDC

Future of food farming 2030's- 14% dec in rice and wheat and 10% dec in Maize in NE Brazil. East Africa will see a 3% decrease in Maize

35 of 43

Implications of climate change for people and the

  • Blizzard- heavy snowfall driven by strong winds, found in high latitudes and mt regions
  • Severe cold spell- cold spells- occurs in continental rather than oceanic location
  • Droughts- spells of slow rainfall- subtropics and continental interiors
  • Heatwaves- spells of abnormally high heat- mid-latitudes in summer
  • Tornadoes- violent, rotating funnel of air in contact with the ground- continental interiors 
  • Mid-lat depression- Large, mobile, low-pressure system which forms on the jet stream and brings heavy rain and gale force winds- mid to high lat
  • Heavy rainfall- intense, short lived thunder storms or prolonged rainfall- widespead
  • Tropical cyclone- Large, violent revolving storms generating hurricane force winds and torrential rain-mid-high lat

Since 1970's the frequency, intensity and duration of extreme weather have increased.

  • Heavy rainfall - increased flooding, destroys crops, increase risk of landslides, the spread of vector born diseases e.g. July 2016 <6 inches of water fell in Maryland = $22 million damage
  • Tropical cyclone- removes forest canopy so habitat affected, post standing water causes disease spread, destroy homes/infrastructure e.g. Hurrican Katrina 05 killed 1,836 and broke through Leveés
  • Powerful depressions- accelerate coastal erosion 
  • Heatwaves- death, toxic air, sagging powerline effects electricity, degradation of water quality e.g. Europe 03, 35,000 deaths, the majority over 75 
  • Droughts- food supply shortage, crops destroyed (lose money), migration of wildlife, increased wildfires- kill/put stress on endangered species
36 of 43

Mitigation strategies to cut global emissions

Energy efficiency and conservation

  • The UK's domestic demand accounts for nearly one-third of primary energy consumption.
  • Building regulations ensure new homes and offices conform to minimum heat insolation and limits to the ratio of window/door space to the floor area.
  • Energy performance certificates are required for all new buildings completed since 2008.
  • The government offers financial incentives to eligible householders to insulate lofts and cavity walls

Fuel shifts and low-carbon energy sources

  • Since 2005, steady decline in energy consumption, 2014, fell by 6.6% and coal consumption fell to levels not seen since 19th century and renewables have expanded
  • Conformed to the EU's renewable energy directive (15% of electricity from renew by 2020)
  • Strategy: expand wind power in offshore location, closing coal-fired stations (e.g. Ferrybridge 2015) and converting some to biofuels
  • The UK still relies on fossil fuels for 86% of energy
37 of 43

Mitigation strategies to cut global emissions

Carbon capture and storage

  • Separate CO2 from power station emissions, then its compressed and transported by pipeline to storage areas. Then it's injected into porous rock deep underground
  • Use is limited by cost and by the shortage of suitable storage sites (old oil and gas fields) for example the Drax project in North Yorkshire was axed in 2016 due to cost (1bilion £)

Geoengineering

  • Use of technology to modify the environment on a large scale
  • 2 strategies: reduce insolation absorbed by earth and atmosphere and remove CO2 from atm
  • Reducing absorption- done by placing huge reflecting plates in orbit or seed the stratosphere with aerosols 
  • Remove CO2- fertilise the ocean with iron, to stimulate phytoplankton growth and increase photosynthesis 
38 of 43

Mitigation strategies to cut global emissions

Reforestation and forest conservation

  • deforestation is responsible for 1/5th of global carbon emissions
  • reforestation and forest conservation is the cheapest and most effective strategy
  • UN promotes its Reducing Emissions from Deforestation Degradation programme. This scheme gives a financial value to carbon stored in forests by providing incentives to developing countries to conserve forests and reduce CO2 emissions
39 of 43

Framework for adaptation

Retreat strategy

  • Managed realignment: vulnerable coastlines, with few settlements, are set back inland, where the risks of flooding and erosion are less, In England and Wales this is supported by Defra and local authorities
  • Retreat strategies also operate in areas near river valleys at risk from flooding 
  • Land-use zoning: prevents housing and businesses locating on floodplains
  • Poverty dictates that nearly 140million live in the Ganges-Brahmaputra Delta, a region exposed to storm surges/violent floods (1970 and 1991 storm surge caused huge loss of life)

Accommodation

  • Affects growing conditions, crop type, cultivation practices, and crop yield
  • new crop strains: adapted to shorter or longer growing seasons
  • irrigation extended in regions of water shortage as well as more efficient irrigation e.g drip
  • Livestock farming or tree crops could replace cereal cultivation in areas of rain deficit
  • conserve soil moisture: zero tillage, rotating crops, drought-resistant crops and mulching
  • Poorer countries find it harder to adapt
  • Efficient water usage: reduce leaks, recycle water and use grey water or more costly, increase reservoir capacity
  • Improve education and public awareness of hazards and provide earlier warning
  • This beginning to happen through increased communications 
40 of 43

Framework for adaptation

Protection strategy

  • Hard engineering- seawalls, dykes and storm surge barriers (Eastern Schelde, Netherlands) protect low lying coastal regions 
  • Soft engineering- conservation of beaches, saltmarshes, and mudflats provide natural barriers against flooding and erosion in coastal areas
  • Increased water storage- expanding areas of wetland and controlling run-off by afforestation
  • Protect selves from vector-borne diseases with pesticides, drugs, new vaccines and bed nets
  • Improved water treatment and sanitation, together with screening for pathogens could protect communities
41 of 43

Future adaptations to buildings and cities

Buildings

High temp- insulation, increasing albedo with reflective roofing, night-time cooling system, reducing high levels of glazing which trap heat in buildings to improve ventilation and install sunshades over windows

Floods- relocate important services from basements and ground floors, green roofs to increase interception and storage, build houses on stilts

Droughts- rainwater harvesting and using grey-water systems

Cities

High temp- creating green infrastructure to reduce urban heat island effect, trees provide shade, light-colored rooves to reflect heat

Floods- change in land-use to absorb water and increase evaporation as well as slow run-off, greener areas to increase interception and replace impermeable surfaces with permeable

Droughts-develop storage systems to capture water and recycle

42 of 43

Future adaptations to transport and economies

Transport-

Extreme heat improved sleepers and rail fastenings to reduce rails buckling, change grades of asphalt to reduce tarmac melting which causes rutting

Heavy rainfall- improve maintenance and protect piers and abutments with riprap or by concreating around foundations, strengthening seawalls especially on coastal areas or elevating sections of the rail track.

Droughts- disrupts traffic on waterways- river engineering (dredging and groynes) or fleet modification (buoyancy aids allowing vessels to sit higher in the water and couples convoys)

Economies

Most AC's will accommodate the worst effects and other, mainly in the developing world will be harder hit

Most LIDCs are situated in tropics and sub-tropics so rise (2 degrees) in temp will have a bigger effect than in cooler climates

LIDCs rely heavily on climate-sensitive activities (ag and tourism), result in climate refugees. Most will migrate to towns and cities 

43 of 43

Comments

No comments have yet been made

Similar Geography resources:

See all Geography resources »See all Climate change resources »