Climate Change 2017 - Foredragsnotater 1-13 PDF

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Climate change 2017 Indholdsfortegnelse Modul 1 ............................................................................................................................................................. 2 Chapter 1: An introduction to the climate problem..............................................

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Climate change 2017 Indholdsfortegnelse Modul 1 ............................................................................................................................................................. 2 Chapter 1: An introduction to the climate problem...................................................................................... 4 Chapter 2: Is the climate changing? .............................................................................................................. 4 Modul 2 ............................................................................................................................................................. 4 Chapter 3: Radiation and energy balance ..................................................................................................... 5 Chapter 4: A simple climate model ............................................................................................................... 7 Modul 3 ........................................................................................................................................................... 11 Chapter 5: The carbon cycle ........................................................................................................................ 11 Slides............................................................................................................................................................ 16 Modul 4 ........................................................................................................................................................... 27 Chapter 6: Forcing, feedbacks, and climate sensitivity ............................................................................... 27 Chapter 7: Why is the climate changing? .................................................................................................... 31 Slides............................................................................................................................................................ 32 Modul 5 ........................................................................................................................................................... 35 Slides:........................................................................................................................................................... 35 Scheutz: ................................................................................................................................................... 35 Drews:...................................................................................................................................................... 36 Note 2: IPCCs SRES og RCP .......................................................................................................................... 36 Chapter 8: Predictions of future climate change ........................................................................................ 37 Modul 6 ........................................................................................................................................................... 39 Slides:........................................................................................................................................................... 39 Kilde 3: Internet side om konventioner....................................................................................................... 41 Kilde 4: DKs rapport summary ..................................................................................................................... 43 Chapter 13: A brief history of climate science and politics ......................................................................... 43 Chapter 14: Putting it all together............................................................................................................... 45 Modul 7 ........................................................................................................................................................... 45 Slides:........................................................................................................................................................... 45 Note 5: Analyse af IPCC delrapport 2 – DK fokus ........................................................................................ 46 Chapter 9: Impacts of CC ............................................................................................................................. 46 Modul 8 ........................................................................................................................................................... 48 Slides:........................................................................................................................................................... 48

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Note 5: afsnit 2.2 og 2.4 .............................................................................................................................. 51 Note 7: summary, afsnit 4.2 og 4.3 ............................................................................................................. 51 Modul 9 ........................................................................................................................................................... 53 Slides............................................................................................................................................................ 53 Chapter 5: The carbon cycle ........................................................................................................................ 55 Modul 10 ......................................................................................................................................................... 58 Slides:........................................................................................................................................................... 58 Chapter 10: Exponential growth ................................................................................................................. 60 Chapter 11: Fundamentals of climate change policy .................................................................................. 61 Chapter 12: Mitigation policies ................................................................................................................... 62 Modul 12 ......................................................................................................................................................... 63 Slides............................................................................................................................................................ 63 Begreber modul 12 ...................................................................................................................................... 67

Modul 1 Slides: Weather is easy to measure (temperature, precipitation, humidity, wind), is used in short term planning, climate, the statistics of the average condition, is used in long term planning. Climate change definition by IPCC: Climate change is the variation in global or regional climates over time. It reflects changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) or, more recently, human activities.

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General information about the IPCCC, slides 7-9. Shows plots with the variation of the climate change indicators. Explains paleoproxies (examples: written accounts like sea or agriculture journals, paintings, treerings, deep sea sediments, corals etc. they go back about fairly reliably 10 000 years, but are less accurate than hard science). Summary Weather refers to the actual state of the atmosphere at a particular time. Climate refers to a change in statistics of the atmosphere over decades (includes averages and extremes). The IPCC (100s of scientists) review the scientific literature and publish reports on the state of the Earth's climate. The global annual average temperature has increased about 0.8 degrees C over the 20th century This is based on multiple independent observations (temperature records (thermometer, satellites), ice sheets, glaciers, sea ice, ocean heat, ice sea-level, etc. The IPPC concludes that the observed warming is unequivocal. The Earth is now warmer than it has been during the last 400 years. The Earth’s climate has varied over widely over its 4.5 billion year history. The climate has been much warmer and much cooler than today.

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The planet has been cooling for the last 50 million years – very long cooling trend. Over the last few million years, the Earth has oscillated between ice ages and warmer inter glacial periods. Ice ages are 5-8 degrees C cooler than the interglacials. The Earth is currently in an interglacial period

Chapter 1: An introduction to the climate problem -

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Weather vs. Climate: Weather is the actual state of the atmosphere at a specific time. Being used for short-term decisions. Climate is a statistical description of the weather, usually over a long period of a few decades. Being used for long-term decisions. Celsius vs. Fahrenheit: F=C*9/5+32 Room temperature: 22,0 C. Precipitation (nedbør) is an important part of climate, and will determine an area’s climate. The type of precipitation (rain or snow) matters as well, as snow is more long term. We all rely on the stability of our climate Climate change is defined as any systematic change in the long-term statistics… sustained over several decades or longer. Measures averages as well as extremes. IPCC: Intergovernmental panel on climate change. A rise of 2 degrees, little as it might be, is not to be underestimated.

Earth -

Latitude- distance from the equator. Measure of the position in the north-south direction. Longitude: measure of the position in the east-west direction Tropics: the region from 30N to 30S. Covers half the surface area of the planet Mid-latitudes: from 30-60 in both hemispheres. Polars: 60 to the pole

Chapter 2: Is the climate changing? -

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Global and annual average warming is 0.85 C with an uncertainty of 0.2 C between 1880 and 2012 Large number of independent measurements confirm the warming seen by the surface thermometer network (which is the most well studied and reliable source). Global warming is beyond doubt. The earth is currently in an interglacial, which is the period between ice ages. Paleoproxies- long lived, geological/chemical/biological systems that have the climate imprinted on them. PETM- the Palescene -Ecocene Thermal maximum- occurred 55 mio. years ago. Features an abrupt warming of a few degrees Celsius that occurred over a few thousand years. Afterwards, the temperature returned slowly back to pre-PETM

Modul 2

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Chapter 3: Radiation and energy balance -

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Energy is expressed in units of joules (J). The rate at which energy is flowing is referred to as POWER and expressed in watts. 1 W=1 J/s joules per second Internal energy: how fast the atoms and molecules in the object are moving Kelvin scale – proportional to internal energy. K=C+273.15. If the temperature doubles, then the internal energy doubles as well. Photons are small packets of energy. Their characteristic size is known as wavelength. Their wavelength determines how the photons interact with matter. Electromagnetic radiation Energy is transported to the earth from the sun by electromagnetic radiation. This includes visible light, X-rays, microwave, and radio-frequency waves.

Blackbody radiation- everything is emitting photons all of the time. The wavelength emitted is determined by the object’s temperature.

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Wavelengths: between 0.3-0.8 visible to human Between 0.8-1000 mu m are called infrared. All room temperature objects are emitting photons but you cannot see them because they fall outside the visible range. Blackbody- at room temperature the object appears black because the photons emitted are invisible to humans. The relation between the temperature and the peak of the object’s emission spectrum Wien’s displacements law

T- temperature in kelvin and lambda max is the wavelength of the peak of the emission spectrum in microns. Important: objects do not just emit photons at lambda max but over a range of wavelengths around this point.

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The total power emitted by an object increases by its temperature

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Stephan Boltzmann equation- describes the relation between the total power radiated by a blackbody and temperature

P/a is the power emitted by a blackbody per unit of surface area.

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T is temperature in kelvin. -

Energy balance: energy is conserved Change in energy balance: Change in temperature is proportional to change in internal energy= energy in – energy out.

Chapter 4: A simple climate model -

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Climate model- energy The sun puts out 3,8*10^26 W Surface area of the sphere is 4**r^2 In case of the sun 4**150.000.000^2=2,8*10^23 m^2 Intensity of the solar radiation- Solar constant for the earth –S= 1360 W/m^2 The total energy falling on the earth is *r^2 * S (where r is the radius of the earth) Earth- radius is about 6400 km Solar energy is falling of the earth at a rate of 1,8*10^17 W or 180.000 TW Human society today consume 16 TW so there are a lot more potential Albedo- some of the photons are reflected back to space by clouds, ice, and other reflective elements The earth’s albedo  is 0.3 Energy in for the earth is If we evaluate it for the earth it will be around 120.000 TW Energy in for the earth per square meter of the earth

We will get by plugging the earth’s values a value of 238 w/m^2 for Energy in There are great variations in the amount of solar energy falling on the earth’s surface, depending on latitude. The tropics get most solar energy, whole the polar almost don’t get any. Perpendicular, rotated away from perpendicular and parallel

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Energy loss to space: Joseph fourier The earth is losing energy at a rate equal to the rate which it is receiving energy from the sun (blackbody radiation) To calculate Energy out we use the same method (with Stefan Boltzmann constant) and put energy in=energy out

By adding the earth’s values, we obtain that T=255 K=-18 C The Greenhouse effect One layered model

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There must be energy balance: Energy in=Energy out Temperature of the surface: The surface is emitting 476 w/m^2. Solving it with Stefan Boltzmann, will lead to T= 303 K= 30 C The surface is heated not only by the sun but also by the atmosphere Two layered model

We want to enforce an energy balance for the planet as a whole. The easiest way is to start with the upper layer and go downwards. It totals that the surface is emitting 714 W/m^2 which means that the temperature must be T=335 K= 62 C

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n-layered model Here we assume a solar constant of 2000 w/m^2 and an albedo of 0.7, which means energy in of 150 W/m^2

We know that the last layer n is emitting 150n both ways, which means that the surface will emit 150(n+1) W/m^2. It is now possible find the temperature T of this planet

As you add layers, the surface gets hotter, but the warming is not linear. The general solution for the surface temperature of an n-layer planet is

Other planets (Mercury, Venus, earth, mars)

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Modul 3 Chapter 5: The carbon cycle -

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Carbon dioxide is the primarily greenhouse gas emitted by human activities. Policies to reduce GHG focus often on this gas. The carbon cycle- how carbon moves between the atmosphere, ocean, land biosphere, and rocks on the earth. GHG absorb infrared photons/radiation (longwave) and they are responsible for the earth’s green house effect. The absorbed energy is transferred to kinetic energy (vibration and rotational excitations of molecules) GHGs re-emit infrared radiation Each GHG has an individual absorption pattern Atmosphere indhold/contains 78% of the dry atmosphere (excl. water vapour) is N2, diatomic nitrogen. 21% of it is oxygen, O2 1% argon, which means that 99% of the atmosphere doesn’t absorb infrared photons Water vapour, or H2O is the next biggest component of the atmosphere, varies from 0.2 to 4% of the atmosphere. In the stratospheres is about 0.0005%. Main source is evaporation from the oceans. Slides: Concentrations range from 20.000 ppmv in the lower troposphere to a few ppmv in the stratosphere. 0.05% of the atmosphere is GHG, whereas CO2 is 0.04% or 400 ppm

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Most important GHG 1) water vapour 2) CO2 0.04 or 400 ppm in 2014 3) CH4 methane 1.83 ppm in 2014 4) N2O- 0.32 ppm (lattergas or laughing gas) 5) O3 – ozone. Abundance varies widely across the atmosphere- about 10-40 ppb. In the stratosphere can be about 10 ppm (1000 times higher). Absorbs high-energy ultraviolet photons. But ground-level ozone can damage plants and breathing it can lead to health problems. 6) Halocarbons- (e.g. chlorofluorocarbons) synthetic industrial chemicals. Only presents as few parts per billion, but are powerful GHGs. Most powerful GHGs per molecule basis are halocarbons

GHGs and their lifetime and GWP (global warming potential)

Carbon cycle Atmosphere- Land biosphere exchange -

In May, there is about 6 ppm more CO2 than in September. The annual cycle reflects the annual cycle of plant growth and decay.

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Photosynthesis plants absorb CO2 from the atmosphere and use it to produce more plant material. CO2, water and sunlight combine to produce CH2O (carbonhydrates) and O2. Main source of oxygen in the atmosphere. o Respiration: consuming plant material in order to produce energy. Results in CO2 released to the atmosphere. The net effect is the conversion of sunlight into energy to power living creatures. 850 GtC in the atmosphere in 2014 (only carbon, without oxygen). Or 3100 GtCO2. 1 GtC=3.67 GtCO1 2500 GtC in the land biosphere, stored in living plants and animals and organic carbon in soils. Photosynthesis removes about 120 GtC from the atmosphere yearly. Respiration balances it. Most of the earth’s land area and plants are in the Northern hemisphere which means that during the north’s summer and spring global photosynthesis exceeds respiration, and vice versa during fall-winter. Large amount of carbon in permafrost. When the ice melts the organic matter, stores will begin to decay, releasing carbon into the atmosphere. o

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Atmosphere- ocean carbon exchange -

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Ocean acidification: CO2 is readily dissolves in water and converted to carbonic acid (H2CO3- 5.3) Carbonic acid reacts with water and convert to many other forms of carbon. That’s why the ocean can absorb huge amounts of CO2. Carbon can also escape back into the atmosphere (5.4) Both processes transfers about 80 GtC per year between the atmosphere and the ocean. The ocean split to 2 parts o Top 100 m- The mixed layer- exchange carbon rapidly. Makes up for a few percent of the oceans. Contains 900 GtC o The deep ocean, which is 97% of the oceans. Contains 40.000 GtC- 47 times more than the atmosphere. The 2 parts of the oceans exchange around 100 GtC per year. Occurs with biological carbon pump. When sinking organic matter, such as dead organisms or fecal material falls from the mixed layer to the deep ocean.

Combined system

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Turnover times: (can be called lifetime/residence time). the size of the reservoir divided by the total flux out of the reservoir o Atmosphere 850/200= atmospheric turnover time of about 4 years o Land biosphere 2500/120=21 years o Mixed layer 900/180=5 years ...