Climate Change Revision

What evidence is there to suggest climate change is a natural process?

Throughout Earth's history there has been interglacial (warmer) and glacial periods - last 2000 yrs has seen Medieval warm period (950-1250) and Little Ice Age (1300-1870

What evidence is there for climate change over the past 2.6 million years?

Sea ice positions: volume of sea ice at Arctic is studied using satellite images - max. and min. sea ice extent each year is studied

Ice cores: new layer of ice forms at poles each year - scientists drill and remove ice cores dating back 800,000 years. Study O16(colder) and O10(warmer) isotopes - if there's more O16 in ice it was colder & if there's more O18 in ice it was warmer.

Tree rings: Tree rings grow a ring every year of their lives - when rings are wide tree grew a lot meaning warmer temperatures - when rings are narrow tree didn't grow that much meaning colder weather

Global temperature data: from 1880 reliable records of temp. available - today 1000+ weather stations collect data & new stations added every yr =more reliable 

Paintings and diaries: show us what past temp was like - paintings show river thames frozen (several months) with frost fairs

Is this data accurate?

Sea ice positions: only gives a 2D - doesn't tell us volume etc., only been studying sea ice postitons since 1979 (not that long)

Ice cores: taking multiple samples is difficult, no human interference with data, has been compared to other data and has been proven reliable and accurate

Tree rings: not that long ago, may not be accurate and you have to interfere with living tree

Global temperature data: records only date back to 1880, recorded the warmest/coldest day since 1880 (not that long ago), some feel not enough stations given an accurate picture, some stations may not be collection accurate readings

Paintings and diaries: sources can be subjective(only one persons point of view), some 'use their imagination' and exaggerate truth, many sources describe same situation adds weight to argument that it is accurate

With no cars/factories in Medieval warm period=MUST be natural causes of warmer climate

Variations in the Earth's orbit - Milankovitch cycles:

• every 100,000 yrs Earth's orbit changes from elliptical to circular - when orbit is elliptical earth is closer to sun at some points & further away at some points
• Earth's tilt on its axis changes - when tilt is smaller, summers=cooler and winters=milder
• Earth's axis wobbles affecting solar input and length of seasons

Ice Ages are more common when elliptical orbit takes Earth away from sun, Earth has less tilt and Earth's axis wobbles

Sun Spots: Dark patches on sun(caused by magnetic storms)-when there are more spots=solar input increased, gets warmer. Little ice age relates to period with fewer pots and medieval warm period with more

Volcanic Eruptions: when large eruption huge quantities thrown into atmosphere=block sun's rays, Earth cools - Medieval warm period=fewer volcanoes & little ice age=more-->extinction of dinosaurs linked to huge volcano that cooled climate, plants didn't grow & dinosaurs starved 

Positive Feedback Loops:

Small changes in temperature can lead to much bigger changes - ice at poles is white = reflects sun's rays and keeps it cold. When ice melts reveals darker surface that absorbs sun's rays, causing temperatures to rise even further

Human causes of climate change

Sun's rays come down to Earth as short waves - light waves. They bounce off Earth's surface and convert long waves - heat waves. Heat waves are trapped by greenhouse gases (carbon dioxide, methane) in the atmosphere. We need 'natural' greenhouse effect to keep Earth warm enough to substain life

Concentrations of greenhouse gases have risen greatly since Industrial Revolution - linked to human actions. The greater the concentration of greenhouse gases, the more heat is trapped and the warmer the Earth becomes

Methane: 25 times more efficient than carbon dioxide at trapping heat - accounts for 15% of enhanced greenhouse effect. Sources incl. farming in paddy fields(growing more to feed growing population) and cattle farming(cow's fart=methane)- for our diet (red meat)

Nitrous Oxide: 250 times more efficient than carbon dioxide at trapping heat - accounts for 6% if enhanced greenhouse effect. Main source incl. agricultural fertilisers and car exhausts

Carbon Dioxide: accounts for 60% of enhanced greenhoue effect. Sources incl. burning fossil fuels(factories,cars,power stations) - deforestation removes trees, carbon sink, so a greater concentration of carbon dioxide remains in atmosphere. ACs produce huge quantities of carbon dioxide - cars, areoplanes, food, phones and electrical products.

LIDCs (incl. most african countries) produce very little carbon dioxide.

ECs like India, are developing similar industry & lifestyle to ACs, carbon dioxide emissions will continue to rise

If cars become more affordable in EDCs and LIDCs=even greater concentrations of carbon dioxide will be produced

China argue that 'total emissions' can be misleading-have 1.36 million people compared to 320 million in USA, when considered 'per capita' their emissions are much lower

China produces huge amount of products overseas (made in China) - they argue that emissions should count for country using products

Carbon Footprints: amount of carbon dioxide released into atmosphere as a result of activites of country/individual - takes into account lifestyle choices in ACs and emissions produced in EDCs and LIDCs to meet those demands - using this measure ACs (USA, UK..) produce far more emissions than EDCs like China.

Sea Level Rise due to:

• Thermal expanison-as waters warm up, water molecules expand and level of water rises
• melting glaciers and ice caps

Since 1901 sea levels risen by 20cm-by 2100 predicted to rise between 50cm-1m. Will have serious implications for low-lying land (e.g Bangladesh)

• 1m rise in sea level=15% of Bangladesh under water
• salty water gets into water supplies-watering crops with salty water kills them
• unable to drink salty water
• people move inland - overcrowing 

Small, low lying lands in Pacific&Indian Ocean=high risk from sea level rise e.g. Tuvalu (highest point only 4.5m above sea level)-salt water gets into their water supplies, warmer waters absorb CO2=more acidic->reduces no.of fish locals rely on. New Zealand agreed to take 75 a yr as 'environmental refugees'

More Extreme Weather

• warmer waters=more powerful hurricanes
• heatwaves more common=more drought
• extreme rainfall more common=increased risk of flash flooding

Increased Drought & Desertification

• changing patterns of rainfall, warmer temperatures and more extreme rainfall affect growth of crops
• Northern parts of world will benefit from warmer temp=more food produced
• Mediterranean & most of Africa=hotter, less food & less water - crops & yield in sub-saharan africa could be 22% les by 2050

2016 Heatwave India -broke highest temp recorded in country with 51 degrees celsius

• power cuts triggered due to surging demands
• tens of thousands farmers forced to leave fields and migrate to towns&cities=overcrowding
• rivers and lakes dried up->dehydration and heatstroke cases (increased)

Lake Chad in central Africa=one of world's greatest lakes - water used by 30 million across Chad, Nigeria and Niger (drinking, food and income). Today=80% smaller than in 1970s - is shrinking due to series of droughts->cannot be replaced by rainfall - rainfall reduced in region by 5-10mm/yr - less rain=more water extract water for crops --> disappearing lake created conflict in region as countries argue over houch each extracts

The Arctic 

• polar bears rely on ice to hunt-no ice=no breathing holes (for seals) means they can't hunt and starve to death
• as climate warms foreign species migrate-disrupt food chains
• Inuit able to grow crops, keep sheep, bring money into economy-->as ice melts able to sail across world rather than around - saves 10 days travelling from Asia to Europe

Ethiopia - Insects&pests living longer and migrating to new areas. Coffee=extremely important for Ethiopia's economy - Coffee Berry Borer Beetle threatens country's coffee crop as beetle thrives in warmer temp and attacks coffee berries. 700,000 farmers in Ethiopia depend on coffee for income

Social

• people starve
• people forced to migrate & places inland become overcrowded
• salt water gets into water supplies - conflicts over water that's shared

Economic

• price of food increases
• cost of building sea defences=high
• crops destroyed & tourist attractions forced to close

Environmental

• sea levels rise-->coastal landforms=submerged
• Oceans become acidic
• rivers and lakes dry up

UK's climate expected to:

• increase average temperature
• have warmer, wetter winters & have warmer, drier summers

Impacts on weather Hazards:

Extreme Rainfall: UK likely to experience extreme rainfall esp.in winter - increase risk of river flooding (flash flooding) - damaged caused by floods=increase, 2015 UK experienced flooding - Storm Desmond broke UK's 24hr rainfall record=341mm in Cumbria

• roads blocked
• 3500 properties flooded
• fooball fixtures cancelled
• railway lines flooded and trains cancelled
• £6bn damage

Extreme Heat

• people suffering from breathing difficulties (asthma) more likely to become ill in extreme heat->air pollution inreases
• more bacteria breeds on food=more cases of salmonella
• higher temp&less summer rain=water shortages esp.in London and S.East as 1/4 of UK population live there->water restrictions(hose pipe bans)
• water shortages affect industry-power stations need a lot of water, may be forced to shut down during droughts
• farmers face waters shortages (extreme weather also)=harder to grow crops - UK have to rely on importing goods

Sea Level Rise

• 30% UK's population live within 10miles of coast
• low lying areas in danger of floods
• over 100,000 properties in S.East at significant risk of flooding
• Thames barrier=fail to protect from flooding
• Coastal towns important for agriculture&industry - £120bn of infrastructure in danger of flooding
• erosion at coast will increase=millions spent on coastal defences
• coastal towns=large elderly population - elderly less able to cope with flooding

Changes To Industry

• Better climate for tourism & tourism season longer
• warmer weather=more tourists in UK
• good for economy->more money spent in country (e.g hotels, days out, ice cream etc..)