HUMAN FINGERPRINTS (2): CLIMATE MODELS 1. Introduction: detection & attribution 2. Climate models 101 3. Explaining the 20 th century warming trend 4. Pauses and forcings
WHAT IS A CLIMATE MODEL? A climate model is a computer program.
A tiny piece of NASA GISS s ModelE FORTRAN code C**** COMPUTE THE AUTOCONVERSION RATE OF CLOUD WATER TO PRECIPITATION RHO = 1.E5*PL(L)/(RGAS*TL(L)) TEM = RHO*WMX(L)/(WCONST*FCLD + 1.E-20) IF(LHX.EQ.LHS) TEM = RHO*WMX(L)/(WMUI*FCLD + 1.E-20) TEM = TEM*TEM IF(TEM.GT.10.) TEM = 10. CM1 = CM0 IF(BANDF) CM1 = CM0*CBF IF(LHX.EQ.LHS) CM1 = CM0 CM = CM1*(1.-1./EXP(TEM*TEM)) + 1.*100.*(PREBAR(L + 1) + * PRECNVL(L +1)*BYDTsrc) IF(CM.GT.BYDTsrc) CM = BYDTsrc PREP(L) = WMX(L)*CM END IF C**** FORM CLOUDS ONLY IF RH GT RH00 219 IF(RH1(L).LT.RH00(L)) GO TO 220 Source: Kolbert, 2005.
Canadian Centre for Climate Modelling and Analysis CGCM2: ~3.75 grid squares. Source: CCCMA web site http://www.cccma.bc.ec.gc.ca/data/data.shtml
The basic idea of a weather/ climate model: grid boxes and calculations. Source: Ruddiman, 2001, p. 74.
Weather/climate model grid boxes. Source: Mann and Kump, 2009, p. 65.
Calculations in a GCM. Source: Christopherson, 2012, p. 288.
Canadian Centre for Climate Modelling and Analysis CGCM2: ~3.75 grid squares. Source: CCCMA web site http://www.cccma.bc.ec.gc.ca/data/data.shtml
Canadian Centre for Climate Modelling and Analysis CGCM3: ~2.81 grid squares. Source: CCCMA web site http://www.cccma.bc.ec.gc.ca/data/data.shtml
Climate model grid, 1990. Source: IPCC, 2007.
Climate model grid, 1996. Source: IPCC, 2007.
Climate model grid, 2001. Source: IPCC, 2007.
Climate model grid, 2007. Source: IPCC, 2007.
MODEL VALIDATION 1. Can the models reproduce today s climate?
Models vs. observations- temperature changes 1900-2000. Source: IPCC, 2013, AR5.
Models vs. observations- temperature changes 1900-2000. Observations 58 model runs Average of 58 model runs Source: IPCC, 2007, AR4.
Precipitation, observations. Source: IPCC, 2007.
Precipitation, model average. Source: IPCC, 2007.
MODEL VALIDATION 1. Can the models reproduce today s climate? YES (mostly) 2. Can the models reproduce short-term forcings?
1991 eruption of Mt. Pinatubo, Phillipines. Source: USGS
Volcanic eruptions and global cooling: Mt. Pinatubo eruption, 1991. Source: NOAA CPC/UK Hadley Centre.
MODEL VALIDATION 1. Can the models reproduce today s climate? YES (mostly) 2. Can the models reproduce short-term forcings? YES (mostly)
Temperature relative to 1951-1980 average (Celsius) Reconstructions of global average temperature, 1880-2013. Time (year) Source: Drawn from data retrieved from GIStemp, National Climatic Data Center, and Berkeley Earth Surface Temperature websites.
What might explain this change in temperature?
Maybe it s the Sun? Video source: climatecommunication.org
Model predictions (natural forcings only). Source: Mann and Kump, 2009, p. 68.
Model predictions (natural forcings only), and observed temperatures. Source: Mann and Kump, 2009, p. 68.
Model predictions (natural and anthropogenic forcings). Source: Mann and Kump, 2009, p. 69.
Model predictions (natural and anthropogenic forcings), and observed temperatures. Source: Mann and Kump, 2009, p. 69.
Observed spatial patterns of temperature change are best explained by including both natural and anthropogenic forcings. Source: Mann and Kump, 2009, p. 73.
Observed spatial patterns of temperature change are best explained by including both natural and anthropogenic forcings. Source: Mann and Kump, 2009, p. 73.
Temperature relative to 1951-1980 average (Celsius) Reconstructions of global average temperature, 1880-2013. Time (year) Source: Drawn from data retrieved from GIStemp, National Climatic Data Center, and Berkeley Earth Surface Temperature websites.
Different forcings push and pull at temperature. Video source: climatecommunication.org
El Niño years = warmer La Niña years = cooler.
El Niño and La Niña: ocean-atmosphere coupling in the tropical Pacific. Source: Mann and Kump, 2009, p. 90.
El Niño and La Niña: ocean-atmosphere coupling in the tropical Pacific. Source: Mann and Kump, 2009, p. 90.
You can SEE the effects of El Niño and La Niña on sea surface temperatures. http://www.youtube.com/watch?v=vtig9gke gqk&feature=player_embedded
El Niño and La Niña record, 1950-2014. 1998: Huge El Nino year Source: NOAA Earth System Research Laboratory, http://www.esrl.noaa.gov/psd/enso/mei/index.html 2006-2014: Dominant weak La Ninas
Temperature relative to 1951-1980 average (Celsius) Reconstructions of global average temperature, 1880-2013. Time (year) Source: Drawn from data retrieved from GIStemp, National Climatic Data Center, and Berkeley Earth Surface Temperature websites.
El Niño and La Niña record, 1950-2014. 1998: Huge El Nino year Source: NOAA Earth System Research Laboratory, http://www.esrl.noaa.gov/psd/enso/mei/index.html 1950-1975: Dominant La Ninas 2006-2014: Dominant weak La Ninas
El Niño and La Niña explain SOME, but NOT ALL, of the temperature record.
El Niño years = warmer La Niña years = cooler. as shown in these data graphics from SkepticalScience.com http://skepticalscience.com/graphics/enso_temps_1024.gif http://www.skepticalscience.com/graphics.php?g=52