The research agrees: Humans are causing climate change (consensus on consensus)

Barack Obama: 97% of scientists, including by the way some who originally disputed the data, have now put that to rest. They’ve acknowledged the planet is warming and human activity is contributing to it. John Oliver: A survey of thousands of scientific papers that took a position on climate change found that 97% endorsed the position that
humans are causing global warming. Bernie Sanders: Some 97% of scientists who have written in peer-reviewed journals say the following: climate change is real, it
is significantly caused by human activity. David Cameron: 97% of scientists the world
over have said that climate change is urgent, and man-made and must be addressed. John Cook: For over a decade, study after
study has found that 97% of publishing climate scientists agree that humans are causing global
warming. But what do the general public think? I’m here at the Brisbane city mall to find
out. John Cook: What percentage of climate scientists, do you think, agree that humans are causing global warming? Member of public: ninety-five percent. probably fifty percent seventy-five percent I think. Person Left: Eighty percent. Ya. Person Right:
Eighty-five. John Cook: Would you like to know who was
closer then? Person Left: I think I was closer. A hundred percent between five and ten percent Um, not a lot. Oh hang on, sorry, other way around. Ninety-five
percent A split about fifty/fifty Person Right: I would say eighty percent Ninety-five percent Person Left: I would say fifty (sighs) half John Cook: There’s a huge gap between what
many of the public think about the scientific consensus, and the actual 97% agreement among
climate scientists. Why is there such a large consensus gap? One contributor is misinformation. Rick Santorum: The 97% figure that’s thrown
around, the head of the U.N. I.P.C. said that number was pulled out of thin air. John Christy: That 97% number, that’s been
debunked in several studies. Richard Tol: This 97% is essentially pulled
from thin air. Ted Cruz: The stat about the 97% of scientists
is based on one discredited study. Bill Maher: …97% of all scientists believe…
Rick Santorum: That’s a bogus number Bill Maher: It’s so not a bogus number
Rick Santorum: It’s so a bogus number Bill Maher: Okay, yours is, mine is, yours
is, mine is! From clips like this, you’d think there’s
vigorous debate about whether scientists agree that humans are causing global warming. We’re
often exposed to contradictory messages in the media. How do we see through the misinformation
and get to the truth about consensus? I joined with scientists who authored seven
of the key studies into the consensus on climate change. When we looked collectively at the
wide range of consensus studies, we found that the expert scientific consensus on human-caused
global warming is between 90 to 100%. The higher the expertise in climate science,
the stronger the agreement on human-caused global warming. When you get to climate scientists
who have published peer-reviewed climate research, there’s 97% agreement. But the fact that consensus gets stronger with
higher expertise is exploited by those looking to cast doubt on the consensus. They do this
by selecting groups of scientists that have lower expertise in climate science to get
a lower level of scientific agreement and argue that there is no consensus.
Using non-experts to cast doubt on the expert consensus is a key characteristic of science
denial known as the appeal to fake experts. This approach was employed by Richard Tol
in a comment criticising the 97% consensus. Tol misrepresented a number of consensus studies,
portraying non-expert groups as representative of the expert consensus. The scientists who
authored those studies were none too happy with how their research was misrepresented. But on the positive side, Tol’s misrepresentation
of all those studies brought the authors of seven key studies together to publish a full
view on the scientific consensus on climate change. Our paper established a consensus
on the consensus being between 90 to 100% expert agreement on human-caused global warming,
with a number of studies finding 97% consensus.

Comments 7

  • What is affecting earth's climate more? Minor fossil fuel (CO2), that constitutes 0.04% of the atmosphere – OR – The Sun which is 1.3 million times bigger than Earth, is situated around 150 million kilometers away from Earth and makes a half of the day significantly warmer that the other half? Don't you think that Sun's activity is crucial in understanding Earth's climate? Look at seasons, tiny shift in earths rotaional axis, creats only a tiny difference in distance from the Sun and … we have winter instead of summer. Can these changes have something to do with higher/lower activity of the Sun (dark spots i.e.), rather than some tiny little humans using what is only Earth's natural component? Do you really feel so proud and so important, that you think you can justify taking away people's money and inhibiting their development?

  • "Consensus on consensus", what a glorious rebuttal!

  • All of the experiments & observations that led to the Global Warming projections in the 1810's to 1890's are replicated
    tens of thousands of times PER YEAR (by nearly every entry level college Science student) in Colleges & University around the world.

    "…All of the Scientific Organizations on Earth, (old & respected) have studied the evidence (human observations)
    (Scientific experiments)  (ground digital & satellite Measures)
    & they have voted on the issue
    & ALL of the Scientific Organizations
    (a few by governing board votes) (vast majority by overwhelming votes of memberships)  (Supervised & Verified)
    *have endorsed the
    the RESULTING CLIMATE CHANGES which will require huge changes to our economies, our level of technology & our level of civilization.
    "… a synthesis of consensus estimates on human-caused global warming
        We have shown that the scientific consensus on AGW is robust,
    with a range of 90%–100% depending on the exact question,
    timing & sampling methodology. This is supported by multiple independent studies
    despite variations in the study timing, definition of consensus,
    or differences in methodology including surveys of scientists,
    analyses of literature or of citation networks From a broader perspective,
    it doesn’t matter if the consensus number is 90% or 100%.
    The level of scientific agreement on AGW is overwhelmingly high
    because the supporting evidence is overwhelmingly strong.doi:10.1088/1748-9326/11/4/048002

  • Do you think we will succeed in keeping warming global temperatures below 2 degrees? Personally, I highly doubt it.

  • The sad truth is that there's much more serious concerns and dangers in regards to immediate pollutive effects from energy production than the projected "end of the earth" due to global warming/climate change. If we focus on immediate toxic effects, we can achieve near 100% consensus and potentially alter behavior on our own volition without having to be threatened or jailed by the State in order to comply.

  • "Climate Change was theorized in 1799, Alexander von Humboldt."
    Please notice that that was 1799…a LONG time ago, they knew !
    "Climate Changed Scientifically tied to Global Warming & Human Activity, physicist & astronomer Simeon Denis Poisson, 1811-1827."
    "George Perkins Marsh (1801-1882) author of the 1847 lecture that predicted "human-induced climate change.”
    THEY WERE LECTURING ABOUT GLOBAL WARMING and the resulting Climate Changes, in 1847 !
    “The heat-trapping nature of carbon dioxide & other gases was experimentally demonstrated & PROVED in the mid-19th century.”
    ..( these same fundamental experiments are replicated Every year in nearly every college science class 101, around the world ! …they are put up for critique and every science student takes a shot on the science… for decades, no appreciable critique of the science of Global Warming…not in climatology, not in physics, not in Meteorology, etc.)

    "….The line of empirical evidence that humans are causing global warming is as follows:
    ((there will be a test later !)
    We're raising CO2 levels
    Human carbon dioxide emissions are calculated from international energy statistics, tabulating coal, brown coal, peat, and crude oil production by nation and year, going back to 1751. CO2 emissions have increased dramatically over the last century, climbing to the rate of 29 billion tonnes of CO2 per year in 2006 (EIA).
    Atmospheric CO2 levels are measured at hundreds of monitoring stations across the globe. Independent measurements are also conducted by airplanes and satellites.
    For periods before 1958, CO2 levels are determined from air bubbles trapped in polar ice cores. In pre-industrial times over the last 10,000 years, CO2 was relatively stable at around 275 to 285 parts per million.
    Over the last 250 years, atmospheric CO2 levels have increased by OVER 100 parts per million. Currently, the amount of CO2 in the atmosphere is increasing by around 15 gigatonnes every year.
    (( Instead of 250-285PPM, as it has been for well over 10,000 years, today we are NOW OVER 405PPM ! ))
    (( What has change which has caused this to occur? ))
    Atmospheric CO2 levels and Cumulative CO2 emissions (CDIAC).
    While atmospheric CO2 levels are usually expressed in parts per million,
    here they are displayed as the amount of CO2 residing in the atmosphere in gigatonnes.
    CO2 emissions includes fossil fuel emissions, cement production and emissions from gas flaring.
    ((((( Humans are emitting more than 135 TIMES as much CO2 as ALL of the volcanoes on EARTH, each & every year, COMBINED ! )))))
    >> CO2 traps heat. <<
    According to radiative physics & decades of laboratory measurements, increased CO2 in the atmosphere is expected to absorb more infrared radiation as it escapes back out to space.

    ** In 1970, NASA launched the IRIS satellite measuring infrared spectra.
    ** In 1996, the Japanese Space Agency launched the IMG satellite which recorded similar observations.

    ** Both sets of data were compared to discern any changes in outgoing I.R. energy radiation over the 26 year period

    SOURCE: (Harries 2001).

    What they found was a drop in outgoing radiation at the wavelength bands that greenhouse gases such as CO2 and methane (CH4) absorb energy.
    The change/reduction in outgoing radiation was consistent with Global Warming theoretical expectations.

    ** Thus the paper found "direct experimental evidence for a significant increase in the Earth's greenhouse effect" and Global Warming.

    ((If Infra Red Energy, does not escape, it is retained in our Earth System as rising temperatures…(( in the Oceans, soil and atmosphere ))

    This result has been confirmed by subsequent Research papers using data from later satellites.
    SOURCE: (Griggs 2004)
    SOURCE: ( Chen 2007 )
    Change in spectrum from 1970 to 1996 due to trace gases.
    'Brightness temperature' indicates equivalent blackbody temperature
    SOURCE: (Harries 2001).
    When greenhouse gases absorb infrared radiation, the energy heats the atmosphere which in turn re-radiates infrared radiation in all directions.
    Much of it makes its way back to the earth's surface.
    Hence we expect to find more infrared radiation heading downwards.
    Surface measurements from 1973 to 2008 find an increasing trend of infrared radiation returning to earth.
    SOURCE: (Wang 2009)
    A regional study over the central Alps found that downward infrared radiation is increasing due to the enhanced greenhouse effect.
    SOURCE: (Philipona 2004)
    Taking this a step further, an analysis of high resolution spectral data allowed scientists to quantitatively attribute the increase in downward radiation to each of several greenhouse gases.
    SOURCE: (Evans 2006)
    The results lead the authors to conclude that "this experimental data should effectively end the argument by skeptics that no experimental evidence exists for the connection between greenhouse gas increases in the atmosphere and global warming."
    Spectrum of the greenhouse radiation measured at the surface.
    Greenhouse effect from water vapor is filtered out, showing the contributions of other greenhouse gases.
    SOURCE: (Evans 2006)
    The planet is accumulating heat
    When there is more energy coming in than escaping back out to space, our climate accumulates heat. The planet's total heat build up can be derived by adding up the heat content from the ocean, atmosphere, land and ice.
    SOURCE: (Murphy 2009)
    Ocean heat content was determined down to 3000 metres deep.
    Atmospheric heat content was calculated from the surface temperature record and heat capacity of the troposphere.
    Land and ice heat content(eg-the energy required to melt ice)were also included.
    Total Earth Heat Content from 1950.
    SOURCE: (Murphy 2009)
    SOURCE: (Ocean data taken from Domingues et al 2008.)
    From 1970 to 2003,
    the planet has been accumulating heat at a rate of 190,260 gigawatts with the vast majority of the energy going into the oceans.
    Considering a typical nuclear power plant has an output of 1 gigawatt, imagine 190,000 nuclear power plants pouring their energy output directly into our oceans.
    What about after 2003?
    A map of of ocean heat from 2003 to 2008 was constructed from ocean heat measurements down to 2000 metres deep .
    SOURCE: (von Schuckmann 2009)
    Globally, the oceans have continued to accumulate heat to the end of 2008 at a rate of 0.77 ± 0.11 Wm?2, consistent with other determinations of the planet's energy imbalance.
    SOURCE: (Hansen 2005)
    SOURCE: (Trenberth 2009).

    The planet continues to accumulate heat.

    1. So we see a direct line of evidence that we're causing global warming. Human CO2 emissions far outstrip the rise in CO2 levels.

    2. The enhanced greenhouse effect is confirmed by satellites and many surface measurements.

    3. The planet's energy imbalance is confirmed by summations of the planet's total heat content and ocean heat measurements…." (which have been duplicated dozens of time around the world)

  • No offense sir, 97% of scientist is not the same as 97% of Climate scientist.
    Science is not politics, it is not a popularity contest, verifiable data is required.
    I have a hard time listening to people making arguments about things they seem to misunderstand so badly.
    Many times they are just regurgitating talking points prepared for them by their assistants.

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