Environmental Modelling (ENGO 583/ENEN 635)

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1 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Envirnmental Mdelling (ENGO 583/ENEN 635) Lecture Nte n: Mdelling the Effect f Greenhuse Gases n Temperature Dept. f Gematics Engineering; and Centre fr Envirnmental Engineering Research and Educatin Schulich Schl f Engineering University f Calgary Review f Last Tpics Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 1

2 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Tpics f Discussin Backgrund infrmatin Atmspheric cmpsitin Atmspheric lifetime and glbal warming ptential f greenhuse gases Greenhuse effect Increases in greenhuse gases cncentratin Quantificatin the effect f greenhuse gases n glbal temperature Prblem statement Cnceptual mdel Assumptins Frmulating mathematical mdel Mdel utput and effect f greenhuse gases Applicatin f mdel Our understanding Backgrund Infrmatin: Atmspheric Cmpsitin The Earth s atmsphere is mainly cmpsed f the fllwing gases, percent cmpsitins by vlume have been stated in parenthesis 1 : Nitrgen (78%) Oxygen (21%) Argn (0.9%) The remaining gases are called trace gases. The s called greenhuse gases fall in this categry. The prminent greenhuses include as fllws and their respective vlumetric percent cmpsitins have been stated in the parenthesis 2 : Water vapr, H 2 O (0 t 4%) Carbn dixide, CO 2 (0.036%) Methane, CH 4 ( %) Nitrus xide, N 2 O ( %) Ozne, O 3 ( %) 1 (Retrieved n 21 January 2018) 2 (Retrieved n 21 January 2018) Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 2

3 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Backgrund Infrmatin: Atmspheric Lifetime and Glbal Warming Ptential f Greenhuse Gases Gas Atmspheric Glbal Warming Lifetime (yrs) Ptential CO 2 Abut CH N 2 O HFC s* 1.5 t t 11,700 PFC s* 3,200 t 50,000 6,500 t 9,200 SF 6 * 3,200 23,900 *These gases are emitted slely frm human surces Surce: IPCC, 1995 Backgrund Infrmatin: Calculatin f Glbal Warming Ptential (GWP) f Greenhuse Gases IPCC (1990) defines the GWP as the rati f the time-integrated radiative frcing frm the instantaneus release f 1 kg f a trace substance relative t that f 1 kg f a reference gas as fllws: where, TH is the time hrizn ver which the calculatin is cnsidered, a x is the radiative efficiency due t a unit increase in atmspheric abundance f the substance in questin (i.e., Wm -2 kg -1 ), [x(t)] is the time-dependent decay in abundance f the instantaneus release f the substance, and the crrespnding quantities fr the reference gas are in the denminatr. Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 3

4 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Backgrund Infrmatin: Atmspheric Lifetime and Glbal Warming Ptential f water vapr (H 2 O) IPCC calculates bth atmspheric life time and GWP fr varius greenhuse gases, except water vapr. The water vapr is the mst imprtant greenhuse gas due t its relatively high vlumetric percent cmpsitin. Hwever, it has the shrtest atmspheric life time (e.g.,~10 days) 1-2 amng the greenhuse gases. Due t its very shrt stay in the atmsphere, its GWP can be cnsidered negligible Backgrund Infrmatin: Imprtance f CO 2 The glbal warming ptential f CO 2 is 1; while the thers are quite large (e.g., CH4 is 21, N 2 O is 310, and s n). S, why we shuld care abut CO 2 in particular? There are three issues related t each f greenhuse gases, i. glbal warming ptential, ii. atmspheric life time, and iii. vlume ccupied. The vlume f HFC, PFC, and SF 6 in the atmsphere is quite small, thus their impacts are less despite having lnger atmspheric life times and high glbal warming ptential. On the ther hand, CO 2 has the secnd highest vlume amng the greenhuse gases and relatively lnger atmspheric life time (~100 yrs), therefre has a mre prnunced effect. Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 4

Suggested citatin: Hassan, Q.K. 2018. Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada.

5 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Backgrund Infrmatin: Greenhuse Effect ( The greenhuse effect by ZFari frm Wikipedia is licensed under CC BY-SA 3.0; Backgrund Infrmatin: Greenhuse Effect ( Radiatin transmitted by the atmsphere by Rbert A. Rhde frm Wikipedia is licensed under CC BY-SA 3.0; the image has been crpped t keep the tpmst panel. n.png) ~70% f the incming shrtwave radiatin in the range µm passes thrugh the atmsphere. ~70% f the incident shrtwave radiatin is absrbed by the earth surface. These absrbed radiatin is cnverted int heat, which in turn emits lngwave radiatin in the range 8-14 µm. Greenhuse gases trap the utging lngwave radiatin by the earth surface, which reradiates back and causes warming Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 5

6 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Backgrund Infrmatin: Cncentratin f Greenhuse Gases frm 0 t 2005 (Frster et al. 2007) Adpted frm IPCC, 2007; IPCC allws the reprductin f limited number f figures r shrt excerpts f IPCC material withut frmal written permissin prvided that the riginal surce is prperly acknwledged. Surce: IPCC; (135p; Faq 2.1, Figure 1) Backgrund Infrmatin: Increases in Greenhuse Gases Cncentratin The last slide shws the atmspheric cncentratins f CO 2, CH 4 and N 2 O gases. It reveals that their cncentratins have increased since 1750, hypthesized t be attributable t human activities during the industrializatin time-perid. The main reasns fr such increments are as fllws (Frster et al. 2007): The increments f CO 2 cncentratins are primarily due t fssil fuel use in varius sectrs. Anther imprtant factr is the land use change, particularly defrestatin, but has a less prnunced effect in cmparisn t the latter. The increments in CH 4 cncentratin are mainly due t agriculture, landfills, wetlands, and fssil fuel use. The increments in N 2 O cncentratin are mainly due t the nitrgen-based fertilizer uses in the agricultural sectr. Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 6

7 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Prblem Statement Understanding the effect f greenhuse gases n glbal temperature Credits: NASA; Image by Rbert Simmn and Ret Stöckli Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature Cnceptual Mdel Greenhuse gases trap the utging lngwave radiatin emitted in the range 8-14 µm by the Earth surface, cntributing t a steady increase in glbal mean temperature. These cntributins may be quantified, if we can calculate the glbal temperature with and withut presence f greenhuse gases in the atmsphere Assumptins Earth is a blackbdy, i.e., whatever it absrbs frm the sun must be equal t the amunt it radiates Earth is isthermal, i.e., the entire planet exhibits the same temperature whatever lcatin is under cnsideratin The Earth s temperature is preserving steady-state cnditins, i.e., it is nt varying with time. Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 7

8 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Frmulating Mathematical Mdel T sun = temperature f sun (~5800 K) r sun = radius f the sun (~6.96 x 10 8 m) M sun is the ttal radiatin emitted by the sun Earth Sun Accrding t Stefan-Bltzmann s Law, d = average distance between sun and earth = 1.5 x m )! "#$ = & ( where, * = Stefan-Bltzmann cnstant (=5.67 x 10-8 W.m -2.K -4 ) "#$! "#$ =? Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Frmulating Mathematical Mdel T sun = temperature f sun (~5800 K) r sun = radius f the sun (~6.96 x 10 8 m) M sun is the ttal radiatin emitted by the sun Earth Sun d = average distance between sun and earth = 1.5 x m The slar radiatin reaches t the earth, E 0, may be calculated using inverse square law: -. =! "#$ / "#$ =? Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 8

9 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Frmulating Mathematical Mdel R = radius f earth Incident slar radiatin n the earth = E 0 pr 2 if a is the earth s albed (=0.30), then slar radiatin reflected by the earth = E 0 pr 2 a; and slar radiatin absrbed by the earth = E 0 pr 2 (1-a) If T is the temperature f the earth, then Emitted radiatin by the earth = s 4p R 2 T 4 As the earth is a blackbdy, the slar radiatin absrbed by the earth must be equal t the emitted radiatin by the earth (1-a) E 0 pr 2 = s4pr 2 T 4 Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Mdel Output and Effect f Greenhuse Gases The mdelled temperature fr the earth is The average actual temperature f earthis abut 288 K (15 C) The difference between the mdelled and actual temperature is nly ff by %, which may lk like an acceptable errr Hwever, in terms f life n earth surface, the mdelled temperature is terribly wrng As the greenhuse gases play vital rles in glbal warming, the difference f between mdelled and actual temperature is being attributed by the greenhuse gases Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 9

10 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Applicatin f the Mdel Calculate the temperature fr the planets f Venus, Earth, and Mars using the glbal temperature mdel Als, quantify the effect f greenhuse gases fr the abve mentined planets by cmparing the mdelled and their average actual temperatures Curtesy NASA/JPL-Caltech; the image has been crpped and the first three planets have been encircled in red. Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Applicatin f the Mdel Planet Distance t Sun (10 6 km) Atms. pressure (atm) Slar cnstant E 0 (W.m -2 ) Albed (%) Mdelled temp. (K) Actual temp. (K) Greenhuse warming ( C) Venus Earth Mars Nte that the radius f the sun is ~6.96 x 10 8 m Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 10

11 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Quantificatin f the Effect f Greenhuse Gases n Glbal Temperature: Our Understanding Accrding t Masters and Ela (2008): The atmspheric pressure f Venus is abut ~90 times in cmparisn t that f the Earth, and its atmsphere is cmpsed f ~96.5% CO 2. Cnsequently, we bserve significant impact f the greenhuse gas n the temperature. Nte that withut the greenhuse effect, the higher albed f Venus (~75%) wuld certainly make the planet cler than the Earth even thugh it is mre clser t the Sun. The atmsphere f Mars is primarily cmpsed f CO 2. Hwever, due t thin atmsphere, the impact f greenhuse gases is hardly bserved. References Frster, P., V. Ramaswamy, P. Artax, T. Berntsen, R. Betts, D.W. Fahey, J. Haywd, J. Lean, D.C. Lwe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Drland, 2007: Changes in Atmspheric Cnstituents and in Radiative Frcing. In: Climate Change 2007: The Physical Science Basis. Cntributin f Wrking Grup I t the Furth Assessment Reprt f the Intergvernmental Panel n Climate Change [Slmn, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignr and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdm and New Yrk, NY, USA. IPCC, 1990: Climate Change 1990: The Intergvernmental Panel n Climate Change Scientific Assessment [Hughtn, J.T., B.A. Callander, and S.K. Varney (eds)]. Cambridge University Press, Cambridge, United Kingdm and New Yrk, NY, USA. IPCC, 1995: Climate Change 1995, The Science f Climate Change; 2nd Assessment Reprt f the IPCC, p.121; Masters, G.M, and Ela, W.P., Intrductin t Envirnmental Engineering and Science. Prentice Hall Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 11

12 Suggested citatin: Hassan, Q.K Lecture nte n: Mdelling the effect f greenhuse gases n temperature, In Envirnmental Mdelling, Calgary, AB, Canada. Sample Review Questins (1) Describe the atmspheric cmpsitins? What are trace gases and why are the greenhuse gases are called trace gases? What are the varius greenhuse gases and what vlumetric prprtins d they cnstitute in Earth s atmsphere? Describe the atmspheric lifetime and glbal warming ptential fr varius greenhuse gases. Hw can we derive the glbal warming ptential number fr each f the gases (CO2, methane, nitrus xide, etc.)? What is the atmspheric life time and glbal warming ptential (GWP) fr water vapr (H 2 O)? The glbal warming ptential f CO 2 is 1; while the thers are quite large (e.g., CH4 is 21, N 2 O is 310, and s n). S, why we shuld care abut CO 2 in particular? What is greenhuse effect? Is it gd r bad? Justify yur answer. What are the reasns behind increases the cncentratin f greenhuse gases? Sample Review Questins (2) Frmulate a mathematical mdel t quantify the effect n greenhuse gases n glbal temperature. What are the assumptins behind the mdel that may be used t quantify the effect f greenhuse gases n glbal temperature. Why d the values f slar cnstant fr different planets vary frm ne t anther planet? What is albed? What is the relatinship between albed and temperature? Quantify the impact f albed n temperature upn cnsidering a base albed value f 30% with a ±20% variatins. Yu have a glbal temperature mdel t quantify the effect f greenhuse gases n temperature. Yur results shws that they have a significantly higher impact n Venus (~521 C) cmpared t that f bth Earth (~34 C) and Mars (~8 C). Explain the physical reasns behind this phenmenn. Except therwise nted, 2018 Quazi K. Hassan, under a Creative Cmmns Attributin- NnCmmercial-ShareAlike license: 12

Energy Inputs and Outputs

Energy Inputs and Outputs Sun Earth ultravilet visible infrared Bth Sun and Earth behave as blackbdies (absrb 100% incident radiatin; emit radiatin at all wavelengths in all directins) Earth receives energy