"How do we really know humans are causing global warming?*"
*But however you answer my question, don’t cite no U.N. report!
So I’m sure that you, like me, are constantly getting e-mails or blog posts that sound like this:
I have been doing enormous amounts of research in this global warming (caused by man) theories and have concluded that there is not ONE shred of evidence to back it up. Can you PROVE to me that global warming is being caused by mankind?
Hmm. Not one shred of evidence? “PROVE”–in all caps, too! You know this is pointless, but still, it’s the day after your daughter’s first birthday, and you’re feeling in good spirits about humanity [she was very well behaved — didn’t grab any other kids and only needed to be sung to once to calm her down when people tried to make her eat cake she didn’t want (a good sign, I think, that she’s not going to be a sugar addict)], so you decide to reply something like:
This one is easy. Either you believe in science — i.e. we went to the moon, you go to the doctor, you have IT equipment you rely on — or you don’t. If you don’t, I can’t “prove” anything to anybody. If you do, then the IPCC reports — which are nothing more than a literature review by the top scientists in the world, commissioned by and summarized for policymakers, signed off by every friggin’ govt in the world — are as much proof as a human being could possibly want.
[Note to fellow parents — emails edited because I know some young people read this blog.]
So then you get a reply like this:
Sorry Joe but your email back to me is not proof of evidence. As for the IPCC report, I don’t buy into what they say. That is not proof. And yes, I very much believe in science which is why I don’t believe in humans have caused global warming. But my question is simple, what scientific proof can you show me, and I am not talking about some report from the UN, that humans are causing the Earth’s temperature to rise. Also, what is the right temperature for the Earth to be at?
The email goes on to ask for IPCC credentials since, “I have a list of 400 scientists, what they do and why the don’t believe in global warming as being caused by man.”
Oh, one of those. Once you realize the emailer hasn’t even bothered to read some of your recent posts, you send a reply that you think/hope will end things:
If you don’t buy into the IPCC, we have nothing to talk about. You might as well not buy into what the American Medical Association or the National Academy of Sciences says. Why take medicine? Why floss? Why get on an airplane? The IPCC report is a summary of the scientific evidence. Simple as that…. If you are talking about the well-debunked Inhofe 400, I guess you haven’t been reading this or other sites.
In retrospect, “laughable” is better than “well-debunked,” but then we all come up with better things to say after the fact. All one can do is press on and rewrite history on your blog….
Anyway, you turn out to be quite wrong about the effect of your email [duh!], and get this reply:
Your emails are proving my point. You have not even attempted to offer proof of global warming as caused by mankind. As for the IPCC report, I read it. It does NOT offer conclusive proof that man is causing the
Earth’s temp to rise. I will make this even easier for you, just name ONE piece of evidence to
prove global warming as caused by man. Just one! As for James Inhofe, he has provided people with enormous amounts of evidence to debunk global warming as caused by man.
Now you’ve done it, or is that, now I’ve done it. Either way, you/I certainly don’t want some random global warming doubter posting some where that “Climate Progress” — or, even better, the “Center for American Progress” refuses to “name ONE piece of evidence” to support its views [notwithstanding the IPCC, which I guess everybody knows doesn’t count]. Plus, I’m starting to think, hmm, maybe it would be useful to direct some readers to the literature on “attribution” [read, maybe you can turn this otherwise wasted time into a blog post]. So you/I reply:
Sigh. You want some shreds of evidence global warming is caused by mankind, but the IPCC is off limits. Interesting but easy challenge. Let’s start here — It’s a few years old now, but it is the best other review of recent science by the leading experts:
“Detecting and Attributing External Influences on the Climate System: A Review of Recent Advances” [It’s actually by “The International ad hoc Detection and Attribution Group.”]
I assume you have a subscription to Science. This is a good study. “Penetration of Human-Induced Warming into the World’s Oceans.”
Here’s NOAA: “The Detection and Attribution of Climate Change.“
I am personally fond of this often-cited paper by NASA.
[Note to most people — The real place to start is “Understanding and Attributing Climate Change,” by Hegerl and Zwiers et al. but for reasons the first half of this post make clear, I can’t do that here.]
But, of course, being the kind of person you are, you can’t leave it at that:
I have more below at the end. But if you won’t believe the 2500 top climate scientists in the world citing hundreds of the latest studies, why would I believe for one second you would believe any studies I cite.
You hide behind the word “conclusive” — please define that word. As you seem to define it, there is no “conclusive” proof that cigarette smoking causes cancer or even that the sun will come up tomorrow.
Inhofe has no evidence. He has opinions backed up by the misinterpretation of a handful of studies that can’t explain what has actually been happening in the past 50 years. Not that it matters AT ALL to the science, but Al Gore does live what he preaches.
Anyway, if you’re serious about wanting to review the science and don’t trust the IPCC to do it, then you should probably read the following [the bibliography of Hegerl and Zwiers et al.]:
AchutaRao, K.M., et al., 2006: Variability of ocean heat uptake: Reconciling
observations and models. J. Geophys. Res., 111, C05019.
Ackerman, A.S., et al., 2000: Reduction of tropical cloudiness by soot.
Science, 288, 1042–1047.
Adams, J.B., M.E. Mann, and C.M. Ammann, 2003: Proxy evidence for
an El Nino-like response to volcanic forcing. Nature, 426(6964), 274–
Alexander, L.V., et al., 2006: Global observed changes in daily climate
extremes of temperature and precipitation. J. Geophys. Res., 111,
Allan, R.J., and T.J. Ansell, 2006: A new globally-complete monthly
historical gridded mean sea level pressure data set (HadSLP2): 1850-
2004. J. Clim., 19, 5816–5842.
Allen, M.R., 2003: Liability for climate change. Nature, 421, 891–892.
Allen, M.R., and S.F.B. Tett, 1999: Checking for model consistency in
optimal fi ngerprinting. Clim. Dyn., 15, 419–434.
Allen, M.R., and W.J. Ingram, 2002: Constraints on future changes in
climate and the hydrologic cycle. Nature, 419, 224–232.
Allen, M.R., and D.A. Stainforth, 2002: Towards objective probabilistic
climate forecasting. Nature, 419, 228–228.
Allen, M.R., and P.A. Stott, 2003: Estimating signal amplitudes in optimal
fi ngerprinting, Part I: Theory. Clim. Dyn., 21, 477–491.
Allen, M.R., J.A. Kettleborough, and D.A. Stainforth, 2002: Model error
in weather and climate forecasting. In: ECMWF Predictability of
Weather and Climate Seminar [Palmer, T.N. (ed.)]. European Centre for
Medium Range Weather Forecasts, Reading, UK, http://www.ecmwf.
Allen, M.R., et al., 2000: Quantifying the uncertainty in forecasts of
anthropogenic climate change. Nature, 407, 617–620.
Ammann, C.M., G.A. Meehl, W.M. Washington, and C. Zender, 2003: A
monthly and latitudinally varying volcanic forcing dataset in simulations
of 20th century climate. Geophys. Res. Lett., 30(12), 1657.
Anderson, T.L., et al., 2003: Climate forcing by aerosols: A hazy picture.
Science, 300, 1103–1104.
Andronova, N.G., and M.E. Schlesinger, 2000: Causes of global
temperature changes during the 19th and 20th centuries. Geophys. Res.
Lett., 27(14), 2137–2140.
Andronova, N.G., and M.E. Schlesinger, 2001: Objective estimation of the
probability density function for climate sensitivity. J. Geophys. Res.,
Andronova, N.G., M.E. Schlesinger, and M.E. Mann, 2004: Are
reconstructed pre-instrumental hemispheric temperatures consistent
with instrumental hemispheric temperatures? Geophys. Res. Lett., 31,
Andronova, N.G., et al., 1999: Radiative forcing by volcanic aerosols from
1850 to 1994. J. Geophys. Res., 104, 16807–16826.
Andronova, N.G., et al., 2007: The concept of climate sensitivity:
History and development. In: Human-Induced Climate Change: An
Interdisciplinary Assessment [Schlesinger, M., et al. (eds.)]. Cambridge
University Press, Cambridge, UK, in press.
Annan, J.D., and J.C. Hargreaves, 2006: Using multiple observationallybased
constraints to estimate climate sensitivity. Geophys. Res. Lett., 33,
Annan, J.D., et al., 2005: Effi ciently constraining climate sensitivity with
paleoclimate simulations. Scientifi c Online Letters on the Atmosphere,
Arblaster, J.M., and G.A. Meehl, 2006: Contributions of external forcing
to Southern Annular Mode trends. J. Clim., 19, 2896–2905.
Bader, J., and M. Latif, 2003: The impact of decadal-scale Indian Ocean
sea surface temperature anomalies on Sahelian rainfall and the North
Atlantic Oscillation. Geophys. Res. Lett., 30(22), 2169.
Banks, H.T., et al., 2000: Are observed decadal changes in intermediate
water masses a signature of anthropogenic climate change? Geophys.
Res. Lett., 27, 2961–2964.
Barnett, T.P., D.W. Pierce, and R. Schnur, 2001: Detection of anthropogenic
climate change in the world’s oceans. Science, 292, 270–274.
Barnett, T.P., et al., 1999: Detection and attribution of recent climate
change. Bull. Am. Meteorol. Soc., 80, 2631–2659.
Barnett, T.P., et al., 2005: Penetration of a warming signal in the world’s
oceans: human impacts. Science, 309, 284–287.
Bauer, E., M. Claussen, V. Brovkin, and A. Huenerbein, 2003: Assessing
climate forcings of the Earth system for the past millennium. Geophys.
Res. Lett., 30(6), 1276.
Beltrami, H., J.E. Smerdon, H.N. Pollack, and S. Huang, 2002: Continental
heat gain in the global climate system. Geophys. Res. Lett., 29, 1167.
Bengtsson, L., K.I. Hodges, and E. Roechner, 2006: Storm tracks and
climate change. J. Clim., 19, 3518–3543.
Berger, A., 1978: Long-term variations of caloric solar radiation resulting
from the earth’s orbital elements. Quat. Res., 9, 139–167.
Berger, A., 1988: Milankovitch theory and climate. Rev. Geophys., 26,
Berliner, L.M., R.A. Levine, and D.J. Shea, 2000: Bayesian climate change
assessment. J. Clim., 13, 3805–3820.
Bertrand, C., M.F. Loutre, M. Crucifi x, and A. Berger, 2002: Climate of the
last millennium: a sensitivity study. Tellus, 54A(3), 221–244.
Betts, R.A., 2001: Biogeophysical impacts of land use on present-day
climate: near surface temperature and radiative forcing. Atmos. Sci.
Lett., 2, 39–51.
Bigelow, N.H., et al., 2003: Climate change and Arctic ecosystems: 1.
Vegetation changes north of 55 degrees N between the last glacial
maximum, mid-Holocene, and present. J. Geophys. Res., 108(D19),
Bindoff, N.L., and T.J. McDougall, 2000: Decadal changes along an Indian
Ocean section at 32S and their interpretation. J. Phys. Oceanogr., 30(6),
Bjerknes, J., 1969: Atmospheric teleconnections from the equatorial
Pacifi c. Mon. Weather Rev., 97, 163–172.
Boer, G.J., and B. Yu, 2003: Climate sensitivity and climate state. Clim.
Dyn., 21, 167–176.
Boucher, O., and J. Haywood, 2001: On summing the components of
radiative forcing of climate change. Clim. Dyn., 18, 297–302.
Boyer, T.P., et al., 2005: Linear trends in salinity for the World Ocean,
1955-1998. Geophys. Res. Lett., 32, L01604.
Braconnot, P., S. Joussaume, O. Marti, and N. de Noblet, 1999: Synergistic
feedbacks from ocean and vegetation on the African monsoon response
to mid-Holocene insolation. Geophys. Res. Lett., 26, 2481–2484.
Braconnot, P., O. Marti, S. Joussaume, and Y. Leclainche, 2000: Ocean
feedback in response to 6 kyr BP insolation. J. Clim., 13(9), 1537–
Braconnot, P., et al., 2004: Evaluation of PMIP coupled ocean-atmosphere
simulations of the Mid-Holocene. In: Past Climate Variability through
Europe and Africa [Battarbee, R.W., F. Gasse, and C.E. Stickley (eds.)].
Springer, London, UK, pp. 515-533.
Braganza, K., et al., 2003: Simple indices of global climate variability and
change: Part I – Variability and correlation structure. Clim. Dyn., 20,
Braganza, K., et al., 2004: Simple indices of global climate variability and
change: Part II – Attribution of climate change during the 20th century.
Clim. Dyn., 22, 823–838.
Briffa, K.R., et al., 2001: Low-frequency temperature variations from a
northern tree ring density network. J. Geophys. Res., 106(D3), 2929–
Broccoli, A.J., et al., 2003: Twentieth-century temperature and
precipitation trends in ensemble climate simulations including natural
and anthropogenic forcing. J. Geophys. Res., 108(D24), 4798.
Brohan, P., et al., 2006: Uncertainty estimates in regional and global
observed temperature changes: a new dataset from 1850. J. Geophys.
Res., 111, D12106, doi:10.1029/2005JD006548.
Bryden, H.L., E. McDonagh, and B.A. King, 2003: Changes in ocean water
mass properties: oscillations of trends? Science, 300, 2086–2088
Bryden, H.L., H.R. Longworth, and S.A. Cunningham, 2005: Slowing of
the Atlantic meridional overturning circulation at 25° N. Nature, 438,
Burke, E.J., S.J. Brown, and N. Christidis, 2006: Modelling the recent
evolution of global drought and projections for the 21st century with the
Hadley Centre climate model. J. Hydrometeorol., 7, 1113–1125.
Caesar, J., L. Alexander, and R. Vose, 2006: Large-scale changes in
observed daily maximum and minimum temperatures, 1946-2000. J.
Geophys. Res., 111, D05101, doi:10.1029/2005JD006280.
Cai, W., P.H. Whetton, and D.J. Karoly, 2003: The response of the Antarctic
Oscillation to increasing and stabilized atmospheric CO2. J. Clim., 16,
Cane, M., et al., 2006: Progress in paleoclimate modeling. J. Clim., 19,
Carril, A.F., C.G. Men©ndez, and A. Navarra, 2005: Climate response
associated with the Southern Annular Mode in the surroundings of
Antarctic Peninsula: A multimodel ensemble analysis. Geophys. Res.
Lett., 32, L16713, doi:10.1029/2005GL023581.
Chan, J.C.L., 2006: Comment on “Changes in tropical cyclone number,
duration, and intensity in a warming environment”. Science, 311, 1713.
Chan, J.C.L., and K.S. Liu, 2004: Global warming and western North
Pacifi c typhoon activity from an observational perspective. J. Clim., 17,
Chase, T.N., J.A. Knaff, R.A. Pielke, and E. Kalnay, 2003: Changes in
global monsoon circulations since 1950. Natural Hazards, 29, 229–
Chen, J., B.E. Carlson, and A.D. Del Genio, 2002: Evidence for
strengthening of the tropical general circulation in the 1990s. Science,
Christidis, N., et al., 2005: Detection of changes in temperature extremes
during the second half of the 20th century. Geophys. Res. Lett., 32,
Christy, J.R., R.W. Spencer, and W.D. Braswell, 2000: MSU tropospheric
temperatures: Dataset construction and radiosonde comparison. J.
Atmos. Ocean. Technol., 17, 1153–1170.
Chuang, C.C., et al., 2002: Cloud susceptibility and the fi rst aerosol
indirect forcing: Sensitivity to black carbon and aerosol concentrations.
J. Geophys. Res., 107(D21), 4564, doi:10.1029/2000JD000215.
Church, J.A., N.J. White, and J.M. Arblaster, 2005: Volcanic eruptions:
their impact on sea level and oceanic heat content. Nature, 438, 74–77.
Clement, A.C., R. Seager, and M.A. Cane, 2000: Suppression of El
Nino during the mid-Holocene by changes in the Earth’s orbit.
Paleoceanography, 15(6), 731–737.
Clement, A.C., A. Hall, and A.J. Broccoli, 2004: The importance of
precessional signals in the tropical climate. Clim. Dyn., 22, 327–341.
CLIMAP (Climate: Long-range Investigation, Mapping and Prediction),
1981: Seasonal Reconstructions of the Earth’s Surface at the Last
Glacial Maximum. Map Series Technical Report MC-36, Geological
Society of America, Boulder, CO.
Cobb, K.M., C.D. Charles, H. Cheng, and R.L. Edwards, 2003: El
Nino/Southern Oscillation and tropical Pacifi c climate during the last
millennium. Nature, 424(6946), 271–276.
Collins, M., 2000a: The El-Nino Southern Oscillation in the second Hadley
Centre coupled model and its response to greenhouse warming. J. Clim.,
Collins, M., 2000b: Understanding uncertainties in the response of ENSO
to greenhouse warming. Geophys. Res. Lett., 27, 3509–3513.
Cook, E.R., et al., 2004: Long-term aridity changes in the western United
States. Science, 306(5698), 1015–1018.
Coughlin, K., and K.K. Tung, 2004: Eleven-year solar cycle signal
throughout the lower atmosphere. J. Geophys. Res., 109, D21105,
Crooks, S., 2004: Solar Infl uence On Climate. PhD Thesis, University of
Crooks, S.A., and L.J. Gray, 2005: Characterization of the 11-year solar
signal using a multiple regression analysis of the ERA-40 dataset. J.
Clim., 18(7), 996–1015.
Crowley, T.J., 2000: Causes of climate change over the past 1000 years.
Science, 289(5477), 270–277.
Crowley, T.J., et al., 2003: Modeling ocean heat content changes during the
last millennium. Geophys. Res. Lett., 30(18), 1932.
Cubasch, U., et al., 1997: Simulation of the infl uence of solar radiation
variations on the global climate with an ocean-atmosphere general
circulation model. Clim. Dyn., 13(11), 757–767.
Cubasch, U., et al., 2001: Projections of future climate change. In: Climate
Change 2001: The Scientifi c Basis. Contribution of Working Group I to
the Third Assessment Report of the Intergovernmental Panel on Climate
Change [Houghton, J.T., et al. (eds.)]. Cambridge University Press,
Cambridge, United Kingdom and New York, NY, USA, pp. 99–181.
Curry, R., B. Dickson, and I. Yashayaev, 2003: A change in the freshwater
balance of the Atlantic Ocean over the past four decades. Nature, 426,
Dai, A., K.E. Trenberth, and T.R. Karl, 1999: Effects of clouds, soil,
moisture, precipitation and water vapour on diurnal temperature range.
J. Clim., 12, 2451–2473.
Dai, A., et al., 2004: The recent Sahel drought is real. Int. J. Climatol., 24,
D’Arrigo, R., et al., 2005: On the variability of ENSO over the past
six centuries. Geophys. Res. Lett., 32(3), L03711, doi:10.1029/
Delworth, T.L., and T.R. Knutson, 2000: Simulation of early 20th century
global warming. Science, 287, 2246–2250.
Delworth, T.L., and M.E. Mann, 2000: Observed and simulated multidecadal
variability in the Northern Hemisphere. Clim. Dyn., 16(9), 661–676.
Delworth, T.L., V. Ramaswamy, and G.L. Stenchikov, 2005: The impact
of aerosols on simulated ocean temperature and heat content in the 20th
century. Geophys. Res. Lett., 32, L24709, doi:10.1029/2005GL024457.
Delworth, T., et al., 2002: Review of simulations of climate variability
and change with the GFDL R30 coupled climate model. Clim. Dyn.,
Dickson, R.R., et al., 2002: Rapid freshening of the deep North Atlantic
Ocean over the past four decades. Nature, 416, 832–837.
Douglass, D.H., and B.D. Clader, 2002: Climate sensitivity of the Earth to
solar irradiance. Geophys. Res. Lett., 29(16), 1786.
Douglass, D.H., and R.S. Knox, 2005: Climate forcing by volcanic eruption
of Mount Pinatubo. Geophys. Res. Let
I have read many of these, but, unlike you, I trust the IPCC’s ability to analyze them for me. Let me know when you’re done.
Anyway, if nothing else, perhaps this will discourage people from emailing me….
UPDATE: I just realized that the bibliography was cut off after the d’s. Oh well. Let’s see if the emailer notices….