Læringsmål for Klimaændringer besvaret PDF

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Summary

Modul 1:  Explain the difference between weather and climateWeather: The state of atmosphere at specific time Includes temperature, precipitation, wind etc. Climate: The average weather over longer period Statistical description Difficult to measure Describe how to measure weather and climateWeath...

Description

Modul 1: 

Explain the difference between weather and climate

Weather: The state of atmosphere at specific time Includes temperature, precipitation, wind etc. Climate: The average weather over longer period Statistical description Difficult to measure 

Describe how to measure weather and climate Weather can be measured as temperature (thermometer), precipitation (rain gauge), wind (anemometer), air pressure (barometer) Climate change indicators are: Glacier volume Air temperature over land Sea ice area Sea level Ocean temperature Water vapor Sea surface temperature Surface temperature is often measured as anomaly, meaning the difference between the measured temperature now relative to an average of 20-30 years 

Describe how the climate has changed over time Over the course of Earth's history climate has changed dramatically between glacials and interglacials and much warmer periods

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Compile observations that show climate change

The upper 0.75 m of the ocean has warmed by 0.1 pr decade since 1950 In newer history, surface temperature has risen 0.9C the last 100 years Annual precipitation has a rising trend over much of the world The ocean temperature anomaly in the upper parts is up to +0.3 in 2010 compared to 1970-2010 mean Global sea level rise of 0.19 m from 1901 to 2010 - from glacier mass loss and ocean thermal expansion Arctic summer sea ice extent has fallen Northern hemisphere spring snow cover fallen Modul 2: 

Relation between an object's internal energy and temperature Temperature is a measurement of the internal energy of an object - they are directly proportional 

Relation between an object's temperature and its emission spectrum Wien's displacement law describes the relation between an object's temperature and its emission spectrum The blackbody radiation curve will peak at different wavelengths that are inversely proportional to the temperature of the blackbody Wien's displacement law: λ max (peak emission wavelength)= 2897/T(Kelvin) Emissions will be emitted in wavelengths around the peak Not to be confused with reflection. Room temperature objects are visible because they reflect photons within the visible range. Their radiation is infrared however, as their temperature is pretty low. "A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. The name "black body" is given because it absorbs all colors of light. A black body also emits black-body radiation" (from wiki) The sun can be considered a 6000K (surface temp. Of the sun = 5778K) black-body

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Relation between an object's temperature and the power emitted to its surroundings

The Stefan-Boltzmann equation describes the relation between an object's temperature and the power emitted to it's surroundings P/a= σ T 4 −8

Stefan boltzmann constant σ=5.67∗10 (

W 4 )/K 2 m

P/a=power per area = W/ m 2 T = Temp in Kelvin 

Be able to establish a simple climate model Climate model no atmosphere: E¿ =S ( 1−α )∗π∗R S ( 1−α ) 2 =238 W /m E¿ ,area = 4 α=albedo=0.3 for Eart h W S =1360 2 m 2

Energy out = (Boltzmann equation): Planetary energy balance (no atmosphere): E¿ ,area =Eout , area S ( 1−α ) =σ T 4 4

Solving for the earth's temperature using known constants gives a surface temp of -18 C. Number of layers represent the amount of greenhouse gasses in the atmosphere

Understanding the model:

The incoming radiation from the sun passes through the atmosphere because the atmosphere is transparent to the shortwave radiation of the sun Ein must equal Eout The atmosphere emits the Ein in both directions Model for surface temperature for n layers: T=

√ 4

( n+1 ) S(1−α) 4σ

Modul 3: 

Explain the structure of the atmosphere and its composition Layers of the atmosphere are troposphere, stratosphere, mesosphere, thermosphere and exosphere Pressure and air mass decreases rapidly with height (almost all air mas is found below 100 km)

The ozone layer is located in the stratosphere, maximum molar ratio of ozone is found in 20 km height Ozone is naturally formed from chemical reactions involving oxygen molecules and ultraviolet sunlight

Composition of the atmosphere (dry, excluding water vapor): 1 ppm = 0,0001% 1 ppb = 0,0000001% Non GHGs: Oxygen 20,95% Nitrogen 78,08% Argon 0,93% Neon 18,2 ppm Helium 5,2 ppm Krypton 1,1 ppm Hydrogen 0,5 ppm GHGs: Carbon dioxide 400 ppm (0,04%) Methane 1,87 ppm Ozone 40 ppb Nitrous oxide 332 ppb Hydroflorocarbons/chloroflorocarbons 1 ppb Water vapor is a natural GHG, up to 4% in tropics Greenhouse gasses heat by absorbing infrared radiation from Earth's surface This energy is transferred to kinetic energy (molecules vibrate, excite) They then re-emit infrared radiation back to the Earth's surface, heating  Explain Earth's energy balance and the role of GHG in this Incoming solar radiation: 340 W/m^2 30% reflected back by clouds, 100 W/m^2 79 W/m^2 absorbed by the atmosphere (atmosphere is not totally transparent as assumed earlier) 185 W/m^2 of the solar radiation reaches the Earth's surface after this 161 W/m^2 is absorbed, 24 W/m^2 is reflected

The radiation absorbed by the surface is about 3 times the ingoing radiation due to greenhouse gasses, raising the average temperature by around 35 degrees 

Know the main GHG and their accumulation in the atmosphere The main GHG are carbon dioxide, water vapour, methane, nitrous oxide, ozone and HFCs/CFCs  Explain the concept of radiative forcing The strength of different human and natural agents in causing climate change Change in net energy flux in the tropospause (unit: W/m^2) Positive - surface warming Negative - surface cooling 

Explain global warming potentials Global warming potential indicates the strength of GHG compared to CO2 1 GWP = 1 kg of CO2 Calculated over a time interval, 20,100 or 500 years Depends on: Infrared absorption Atmospheric lifetime Spectral location of its absorbing wavelengths Modul 4:

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Explain the carbon cycle and the coupling to increasing atmospheric concentrations of GHGs

The main anthropogenic source of carbon is fossil fuel combustion Emits 80 times the natural carbon flow rate from rock to atmosphere The increase in atmospheric carbon each year is approximately half what is emitted, the other half is taken up by the ocean and land biosphere If a big amount of carbon dioxide is released at once, about 40 percent will be removed in twenty years by the land biosphere and mix-layer ocean After 400 years, about 25 percent still remains after absorption into deep ocean After 10,000 after exchange with rock, 15 percent still remains There is a timelag for the planet to adjust to the new temperature if a lot of GHG is instantenously released, meaning the earth would continue to warm even after we stopped emitting GHG 

Know other factors than GHGs that cause changes in the Earth's energy balance like aerosols, land use change, solar changes Land use change can change the energy balance by affecting albedo, deforestation leads to a higher albedo - more is reflected - human land use changes have net RF of -1.5W/m^2 Aerosols are small particles that reside in the atmosphere and can change the energy balance by reflecting more sunlight back into space - causing a negative net RF Aerosols may be sulfate from volcanic eruptions or from impurities in fossil fuel combustion, black carbon aerosols (have positive net RF). Total net RF of all aersols -0.35 W/m^2

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Know the main feedback mechanisms Main feedback mechanisms: Ice-albedo

Water-vapour

Feedback math: ∆T i ∆Tf= (1−g)

with g being the magnitude of the feedback pr. round that it loops

Based on each round producing an additional warming of g∗∆ T i in response to the initial warming ∆ T i

When g is negative it amplifies the initial warming T_i (because it is divided by less than 1) 

Be able to explain the mechanisms that have caused the climate to change in the past Natural climate change: Variations in the Sun's output (11-year cycle) Variations in the Earth's orbit: Eccentricity - orbit lane 100,000 years cycle Obliquity - changes in the Earth's tilt/spin axis - 41,000 years cycle Precession - 26,000 years cycle

Modul 5: 

Be able to explain how to make projections of climate change through scenarios for greenhouse gas emissions, atmospheric concentrations, radiative forcing and temperature change Scenarios of greenhouse gas emissions are based on estimations of population, economic and technological development as these are the main driving forces A set level of emissions will correspond to a certain radiative forcing Plugging emissions into a carbon-cycle model can calculate what the atmospheric concentration will be Temperature change can be calculated based on the climate sensitivity average (degrees pr increased RF): 0.75C/(W/m^2)/ or an instantenous release of 560 ppm CO2 would give a warming including feedbacks of 2-4 degrees (initial 1.2)  Explain which driving forces are important for estimation of GHG emissions IPAT relation Intensity of emissions = Population x Affluence x Greenhouse gas intensity T = energy intensity x carbon intensity  Know the RCP scenarios and explain the difference between the four main scenarios

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Know the temperature response that the scenarios will give rise to

Modul 6: 

Be able to explain the role of UN in relation to anthropogenic climate change and their main tools - treaties, protocols and COP/CMP meetings COP - Conference of the parties, the COP assesses the effects of the measures taken by the parties and the progress made in achieving the ultimate objective of the convention/treaty Treaties are legally binding Protocols are less formal than treaties, meetings leading to the formulation of a treaty/convention

Important historic UN cops/treaties: The Montreal Protocol on substances that deplete the ozone layer (Agreed 1987, entered into force 1989), a protocol that was an addition to the UN convention on protection of the ozone layer from 1985. 197 countries signed the protocol UN Framework Convention of Climate Change (Rio Earth Summit 1992) - Entered into force 1994. 195 countries + EU. Objective: stabilize greenhouse gas concentrations that would prevent dangerous anthropogenic interference with the climate system. No clear limits to emissions yet, but states that this will be further negotiated in protocols. Annex I countries: industrialised countries + former soviet transitioning to capitalist economies, Annex II countries: industrialized countries that must provide financial and technological support to Non-Annex I countries (developing countries) Kyoto Protocol, signed 1997. Entered into force in 2005 after Russia joined, as Bush had withdrawn the US. First legally binding international commitment with specified obligations. Average emissions 2008-2012 must be 5% lower than 1990 level. Copenhagen Accord 2009: No legally binding commitments Global temperatures should not rise more than 2C beyond pre-industrial temperatures Rich industrialized countries each set their own targets, EU 20-30 percent below 1990 emissions, US 17% below 2005 emissions Developing countries took on mitigation efforts but not specific emissions targets Criticised for not being enough - no legally binding target for after Kyoto Protocol, a failure Paris Agreement, signed 2015 (COP21), enters into force 2020 Same goal as Copenhagen Accord, preferably not more than 1.5 C Countries submit their own goals that must be renewed every 5 years Legally binding 

Be able to explain the role of IPCC, their framework of analysis, working methods and publications The IPCC is a scientific body under the UN Established 1988 by WMO and UN environment 195 member states

Purpose: to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts The IPCC review and assess the most recent findings relevant to the understanding of climate change IPCC working groups: WG1 - physical science basis WG 2 - impacts, adaptation and vulnerability (human health, water resources etc) WG 3 - mitigation (sectors, infrastructure) IPCC have established guidelines for greenhouse gas inventory 

Be able to distinguish between different ways of accounting of GHG emissions Method 1: accounting for all activities, IPCC have established guidelines for this accounting to be unambigous Sectors defined to enable reductions Method 2: attribution to sectors Method 3: Global drivers (Kaya Identity) Method 4: Global equity (socio-economic drivers) Modul 8: 

Be able to read IPCC material (SPM) Confidence: How much research agrees

Likelihood:

Virtually certain

99-100% probability

Very likely

90-100%

likely

66-100%

About as likely as not

33-66%

unlikely

0-33%

Very unlikely

0-10%

Exceptionally unlikely

0-1%

More likely than not

50-100%

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Discuss which types of measures are key to climate change mitigation Change of energy supply mix Carbon capture and storage Bioenergy Change in national investments Agriculture: cropland managementm grazing land management, restoration of organic soils  Discuss which measures are available for climate change mitigation (political economical) Most politicians are not willing to compromise our affluence and population, as for example 1 child policy in china seems to infringing on rights. Affluence = quality of life nowadays so this would not make people happy either. This means that mitigation must be found in the carbon intensity/energy intensity term in IPAT equation Geoengineering Regulation - legislation (command and control) Regulation - carbon tax or cap and trade - these are governed by marginal cost meaning what is the cost for a company to emit one more ton of CO2 vs. The benefit of doing so. They will continue to emit until it is no longer economically beneficial  Discuss the rationale behind discounting and use the method to calculate NPV in relation to climate change mitigation Discounting is used to calculate cost and benefit of things separated in space Can be used to calculate whether an investment in adaptation or mitigation is good compared to the benefit/ saved emissions/saved risk NPV: what is todays value of future costs? Discount rates are subjective

Ministry of climate has a lower discount rate than anyone - a longer sight into the future in what is a good investment because it is about the survival of the human race, an unknown future risk

Discount rate is r

Bt=benefit at time Ct= cost at time Installing a methane collector in a treatment plant, a big investment in the first year to implement the technology - benefits following years from saving electricity:

With a low discount rate as the ministry of climate has, it will be a really good investment as they have in mind that the methane will not be emitted to the atmosphere Modul 9: 

Discuss which physical impacts have already been observed and are likely to occur within near and far futures Already observed: Extreme precipitation events Heatwaves Forest fires Snow cover reduction All will be more likely to occur Crop yield reduction due to weather extremes - increase in some areas where warmer weather is beneficial Ecosystem impacts - migration of species both marine, land and avian 

Be aware of different ways of quantifying impacts Impacts can be measured as changes in mean, variance or or skewness

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Discuss how these impacts will influence the Earth system and human activity Use sea level rise as an example to discuss differences between changes in mean and extremes

Modul 11: -Calculate aggregated climate change costs and cost-benefit of CC adaptation measures for simple examples...