As a practical matter of politics, nobody knows what Kyoto is or what it commits us to. Michael Ignatieff , former leader, Liberal Party of Canada

The Kyoto Protocol is a political solution to a non-existent problem without scientific justification. Dr. Timothy Ball, former climatology professor

Consensus is the business of politics. If it's consensus, it isn't science. If it's science, it isn't consensus. Period. Michael Crichton, author

Until a continuous climate observing system is established, both climate models and observations will remain uncertain. Wielicki et al. Science June 21, 2002

We can no longer absolutely conclude whether globally the troposphere is cooling or warming relative to the surface. Thorne et al, BAMS Oct 2005

We only understand 10 percent of the climate issue. That is not enough to wreck the world economy with Kyoto-like measures. Henk Tennekes, former research director, Dutch Royal Meteorological Institute

The minute you begin to believe your own hypothesis, you're a dead duck as a scientist. Frank Beales - former U. of Toronto Professor

I would freely admit that on global warming we have crossed the boundary from news reporting to advocacy. Charles Alexander, Time magazine science editor

Skepticism is the highest of duties, and unverified belief the one unpardonable sin. Thomas H. Huxley, Biologist

Some people will do anything to save the earth . . . except take a science course. P. J. O'Rourke, author, journalist

We have to offer up scary scenarios (about global warming) ... ...each of us has to decide what the right balance is between being effective and being honest. Stephen Schneider, Stanford University environmentalist

I've just completed Mike's Nature trick ... to hide the decline. Phil Jones, Director of Climate Research Unit, UEA, UK.

Mike, Can you delete any emails you may have had with Keith regarding the latest IPCC report? Keith will do likewise. ...Can you also email Gene and get him to do the same? Phil Jones, Director of Climate Research Unit, UEA, UK

There is no reason to give them any data, in my opinion, and I think we do so at our own peril! Michael Mann, Director Earth System Science Center, Pennsylvania State University

The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't. Kevin Trenberth, National Center For Atmospheric Research, USA

We are nowhere close to knowing where energy is going or whether clouds are changing to make the planet brighter ... We are not close to balancing the energy budget. Kevin Trenberth, National Center For Atmospheric Research, USA

No reviewer has ever asked to see the data. Phil Jones, Director of Climate Research Unit, UEA, UK.

Kevin and I will keep them out [of the IPCC Report] somehow - even if we have to redefine what the "peer-review literature" is! Phil Jones, Director of Climate Research Unit, UEA, UK.

If they [McIntyre and McKitrick] ever hear there is a Freedom of Information Act now in the United Kingdom, I think I'll delete the file rather than send it to anyone. Phil Jones, Director of Climate Research Unit, UEA, UK.

If I were on the greenhouse deniers' side, I would .. focus on the wide range of paleoclimatology results and the differences between them as an argument for dismissing them all. Tom Wigley, University Corporation for Atmospheric Research

Mike, the figure you sent is very deceptive [...] there have been a number of dishonest presentations of model results by individual authors and by IPCC Tom Wigley, University Corporation for Atmospheric Research, USA

Observations do not show rising temperatures throughout the tropical troposphere ... This is just downright dangerous. Peter Thorne, Hadley Centre, Met Office, UK

The trick may be to decide on the main message and use that to guide what's included and what is left out [of the IPCC Reports]. Jonathan Overpeck, Director, Institute for the Study of Planet Earth, University of Arizona

But it will be very difficult to make the MWP [Medieval Warm Period] go away in Greenland. Henry Pollack, University of Michigan

What if climate change appears to be just mainly a multidecadal natural fluctuation? They'll kill us probably. Tommy Wils, Swansea University

Weighting the solar irradiance more strongly in the models, then much of the 19th to mid 20th century warming can be explained from the sun alone. Rob Wilson, School of Geography & Geosciences, University of St Andrews

I am not convinced that the 'truth' is always worth reaching if it is at the cost of damaged personal relationships" Thomas J. Crowley, Nicholas School of the Environment and Earth Sciences, Duke University

This will reduce the 1940-1970 cooling in Northern Hemisphere temperatures. Explaining the cooling with sulphates won't be quite as necessary. Phil Jones, Director of Climate Research Unit, UEA, UK

It is interesting to see the lower tropospheric warming minimum in the tropics in all three plots, which I cannot explain. ...it is remarkably robust against my adjustment efforts. Leopold Haimberger, Department of Meteorology and Geophysics, University of Vienna

I also got recently a paper from Rob which says 'London's UHI [Urban Heat Island effect] has indeed become more intense since the 1960s especially during spring and summer' Geoff Jenkins, Met Office, UK

We found the [urban warming] effect is pretty big in the areas we analyzed. Unfortunately, when we sent our comments to the IPCC AR4, they were mostly rejected. Guoyu Rean, National Climate Centre (NCC) of China, Beijing

I'm sure you agree--the Mann/Jones GRL paper was truly pathetic and should never have been published. Raymond S. Bradley, Director, Climate System Research Center, University of Massachusetts

How can we be critical of Crowley for throwing out 40-years in the middle of his calibration, when we're throwing out all post-1960 data Tim Osborn, Climatic Research Unit, UEA, UK

It will not be models or theory, but observation that will provide the answer to the question of how the climate will change in many decades time. Andrew Watson, School of Environmental Sciences, UEA, UK

There is no individual model that does well in all of the SST [sea surface temperature] and water vapor tests we've applied. Ben Santer, Lawrence Livermore National Laboratory, USA

I doubt the modeling world will be able to get away with this [tuning] much longer Tim Barnett, Scripps Institution of Oceanography, USA

So using the 20th century for tuning [the IPCC models] is just doing what some people have long suspected us of doing Gabriele Hegerl, Nicholas School for the Environment and Earth Sciences, Duke University

Basic problem is that all models are wrong - not got enough middle and low level clouds. Phil Jones, Director of Climate Research Unit, UEA, UK.

I've been told that IPCC is above national FOI Acts. One way to cover yourself and all those working in AR5 would be to delete all emails at the end of the process Phil Jones, Director of Climate Research Unit, UEA, UK.

Any work we have done in the past is done on the back of the research grants we get - and has to be well hidden. Phil Jones, Director of Climate Research Unit, UEA, UK.

Very little research has ever been funded to search for natural mechanisms of warming... it has simply been assumed that global warming is manmade. Roy W. Spencer, University of Alabama in Huntsville

Everyone in IPCC WG3 should be terminated and, if the institution is to continue, it should be re-structured from scratch. Steve McIntyre, Climate Audit