2011-02-15 01:53:00Two Hansen Quotes
Daniel Bengtsson

dbengt@hotmail...
136.163.44.102
Hi everyone!
A couple of times this year I have seen sceptical bloggers claim that James Hansen stated the following in 1986:
 

 

A) Within 15 years, global temperatures will rise to a level which hasn’t existed on earth for 100,000 years.

 

B) Hansen said the average U.S. temperature had risen from one to two degrees since 1958 and is predicted to increase an additional 3 or 4 degrees sometime between 2010 and 2020.

 

The statements are of interest among sceptics at the moment since we have reached the time span of the predictions and since the predictions (in their eyes) seem far too alarming. Today (February 14th), I found a thorough but easy-to-follow post that clarifies what Hansen actually said and shows that (when not taken out of context) the predictions seem to be fairly accurate. The post was published on a Swedish climate blog run by scientists. Would it be interesting for you if the post was translated and posted here for review? I have their permission already.
2011-02-16 11:57:48why not
dana1981
Dana Nuccitelli
dana1981@yahoo...
69.230.107.233
Sounds good to me.  There are a whole lot of myths about things Hansen has said - it wouldn't hurt to debunk a couple of them if you have a resource to do it.
2011-02-16 13:37:05Hansen sea level quote
John Cook

john@skepticalscience...
144.131.205.143

Phil Blackwood emailed me about Hansen's quote on sea level rising above the West Side Highway in 2010 earlier today. I emailed back asking if he'd be interesting in writing a guest post about it (of course). He said he'd write something over the weekend so I'll invite him to the forum when I hear back.

Hansen quotes. James mentioned other quotes taken out of context or plain made up. Could be a whole category on misquotes.

2011-02-16 19:22:55
Riccardo

riccardoreitano@tiscali...
192.84.150.209
Definitely Hansen is one of the most misquoted scientists. Resetting the context is a good idea.
2011-02-21 09:03:08Hansen quotes
Daniel Bengtsson

dbengt@hotmail...
79.136.17.186
Sorry for not writing back earlier. My computer broke down. I'll try to post the translation in a few days time. By Tuesday hopefully. 
2011-02-21 09:28:02
Riccardo

riccardoreitano@tiscali...
93.147.82.174
Don't worry Daniel, shit happens, no doubt :)
2011-02-21 09:37:28Hansen quote
John Cook

john@skepticalscience...
144.131.205.143

Added this new argument:

http://www.skepticalscience.com/Hansen-West-Side-Highway.htm

I've invited Phil onto the forum so hopefully he'll be posting his rebuttal soon.

Maybe we need to have a "Misquotes Week" :-)

2011-02-24 03:29:38
Daniel Bengtsson

dbengt@hotmail...
136.163.44.102

Two Hansen quotes


A couple of times this year two quotes of Dr James Hansen have appeared on “skeptical” web sites with the intention to discredit him. Since it is probably not the first, nor the last time, these statements show up in the climate debate, here is a little about them. The quotes are from 1986 and read:


Quote 1) Within 15 years, global temperatures will rise to a level which hasn’t existed on earth for 100,000 years.


Quote 2) Hansen said the average U.S. temperature had risen from one to two degrees since 1958 and is predicted to increase an additional 3 or 4 degrees sometime between 2010 and 2020.


The statements are of interest among skeptics at the moment since we have reached the time span of the predictions and the predictions in their eyes seem far too alarming.

Searching for the source, one finds that it comes from a short article June 11, 1986 in The Oxnard Press Courier. The article is a report from a committee hearing in the Senate where Hansen testified the previous day. Fortunately, the written testimony of the hearing is available so we can check what Hansen said and in what context.

The hearing is titled Ozone Depletion, the Greenhouse Effect, and Climate Change and deals with both greenhouse gases and the effect of CFCs on the atmosphere. This was before the Montreal Protocol and its international agreement to phase out CFCs. Hansen testified June 10 and the parts of his testimony from which the referenced statements above origin can be found on page 88 (Quote 2) and 92 (Quote 1) in the record. Here follows an extract from these pages:

Page 92) On the other hand, it is also apparent from Fig. 8. that the predicted greenhouse warming for Scenario A rises above the level of natural variability by the 1990’s. Indeed, the model predicts a temperature level in the next 15 years which has not existed on earth in the past 100,000 years, as illustrated below. In view of the significance of such conclusions, we stress here the principal caveats which must accompany the result:

1) The model sensitivity is 4.2°C for doubled CO2. Emergence of the warming signal will be delayed if the true sensitivity is less than that.

2) The projection is based on Scenario A. If Scenario B is more realistic, emergence of the warming signal will be delayed. We estimate that Scenario B would delay the emergence by a few years, but a more quantitative statement requires extension of the Scenario B simulation.

3) Other major climate forcings which tend to counteract the greenhouse warming may occur during the next several years.[...]

4) There may be crucial climate mechanisms which are omitted or poorly simulated in current climate models.[...]



Page 88) “Our GCM simulations begin in 1958, when CO2 began to be monitored accurately by C. D. Keeling, and extend through the present into the future. We consider two scenarios, A and B, to allow for uncertainties about past trace gas changes and future CO2 and trace gas changes.”
[…]
“Scenario A achieves a radiative forcing equivalent to that of doubled CO2 about 40 years from now, in the late 2020’s. Scenario B achieves this level of forcing in about 2060.”
[…]
The detailed geographical patterns of these changes are not to be taken seriously in view of the limitations of current GCM’s mentioned above and the gross assumption about ocean heat transports. However, certain semi-quantitative conclusions are expected to be meaningful.
The warming in Scenario A at most mid-latitude Northern Hemisphere land areas such as the United States is typically 0.5-1.0°C (1-2°F) for the decade 1990-2000 and 1-2°C (2-4°F) for the decade 2010-2020. Even in the latter decade the warming is much less than the equilibrium response to doubled CO2, Fig. 7c, which has a warming at about 5°C in the United States. In all of these cases the largest temperature changes are in regions of sea ice and the smallest are at low and middle latitude ocean areas.”

From the text we conlude:
  • The temperatures in the Oxnard Press Courier article are in degrees Fahrenheit and, at least in the written testimony, Hansen indicates 2-4 °F higher (than late 50s) for 2010-2020, in contrast to 3-4 °F additionally (from mid 80s levels) which is suggested in the newspaper article.
  • The temperature prediction was not specifically for the U.S., but for mid-latitude Northern Hemisphere land areas in general.
  • The statements deduce from a comprehensive description of the modeled results, including reasoning about ranges.
  • Two different scenarios were modeled. Scenario A (which assumed exponential growth in forcings, according to the situation during the early 80s,) and scenario B, (where the increase in forcings was roughly linear). It is results from the high emission scenario A that are described in quotes 1 and 2.
  •  

    Hansen built his testimony on his own and other scientist’s research, discussing the results and describing certainties - just as one would expect from a good scientist. But, taken out of context and partly misunderstood by the journalist, the statements give a different picture. Also, when quoting the article today, it is misleading to a large proportion of the internet audience not to mention which temperature unit is assumed (especially if it is not °Celsius or Kelvin, most commonly used by scientists).

    As it appears above, Hansen did not really make a forecast in the sense that he considered it to be the most likely development, but rather described the outcome of the two scenarios. It is interesting to compare the figures from these early climate models with what we know today. 

    Regarding quote 1) There are of course uncertainties in reconstructions of temperatures over several thousand years, but most indicate that global temperatures at the turn of this millennium was equal or higher than any time since the last ice age, which also means at least 100 000 years. (See for example the IPCC AR4 or Hansen & Sato)



    Source: Wikipedia, http://en.wikipedia.org/wiki/File:Holocene_Temperature_Variations.png



    Regarding quote 2)
    We can plot land temperatures from Northern Hemisphere mid-latitudes using data from GISS. Hansen used the late 50s as reference in the models he referred to. Temperatures in the late 50s are close to the average of the base period used by GISS, thus close to zero in the graph below. During the last couple of years temperatures have been around one degree warmer, so we will probably reach the 1-2 °C temperature span during this decade, albeit the lower half.

               

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              Note: This was originally posted on the Swedish blog Uppsalainitiativet.

2011-02-25 03:51:23
Daniel Bengtsson

dbengt@hotmail...
136.163.44.102
I have received comments on this post while translating it. These include:
·          Removing the Wikipedia graph because the black line doesn’t mean much without error bars that reflect the effect of uncertainty in mapping a few proxies to a global average.
·          Adding a graph where the forcings of Scenario A & B are compared to actual values.
·          Pointing out that 4.2°C/doubling is on the high side of the 2007 IPCC’s range.
However, this translation is still very similar to the original Swedish blog post, so I thought I would leave it like it is until you guys had read it and decided whether the post is worth working on or not.