# Re: a modest proposal [was: Re: [asa] Phil Jones Stepping Down..]

From: Rich Blinne <rich.blinne@gmail.com>
Date: Wed Dec 02 2009 - 17:37:05 EST

We often get requests to provide an easy-to-understand explanation for why
increasing CO2 is a significant problem without relying on climate models
and we are generally happy to oblige. The explanation has a number of
separate steps which tend to sometimes get confused and so we will try to
break it down carefully.

*Step 1:* There is a natural greenhouse effect.

The fact that there is a natural greenhouse effect (that the atmosphere
restricts the passage of long wave (LW) radiation from the Earth’s surface
to space) is easily deducible from i) the mean temperature of the surface
(around 15ºC) and ii) knowing that the planet is roughly in radiative
equilibrium. This means that there is an upward surface flux of LW around
$$\sigma T^4$$ (~390 W/m2), while the outward flux at the top of the
atmosphere (TOA) is roughly equivalent to the net solar radiation coming in
(1-a)S/4 (~240 W/m2). Thus there is a large amount of LW absorbed by the
atmosphere (around 150 W/m2) – a number that would be zero in the absence of
any greenhouse substances.

*Step 2:* Trace gases contribute to the natural greenhouse effect.

The fact that different absorbers contribute to the net LW absorption is
clear from IR spectra taken from
space<http://origins.jpl.nasa.gov/library/exnps/f4-3.gif>which show
characteristic gaps associated with water vapour, CO
2, CH4, O3 etc (Harries et al,
2001<http://www.nature.com/nature/journal/v410/n6826/abs/410355a0.html>;
HITRAN). The only question is how much energy is blocked by each. This
cannot be calculated by hand (the number of absorption lines and the effects
of pressure broadening etc. preclude that), but it can be calculated using
line-by-line radiative transfer codes. The earliest calculations (reviewed
by Ramanathan and Coakley, 1979) give very similar results to more modern
calculations (Clough and Iacono,
1995<http://www.agu.org/pubs/crossref/1995/95JD01386.shtml>),
and demonstrate that removing the effect of CO2 reduces the net LW absorbed
by ~14%, or around 30 W/m2. For some parts of the spectrum, IR can be either
absorbed by CO2 or by water vapour, and so simply removing the CO2 gives
only a minimum effect. Thus CO2 on its own would cause an even larger
absorption. In either case however, the trace gases are a significant part
of what gets absorbed.

*Step 3:* The trace greenhouse gases have increased markedly due to human
emissions

CO2 is up more than 30%, CH4 has more than doubled, N2O is up 15%,
tropospheric O3 has also increased. New compounds such as halocarbons (CFCs,
HFCs) did not exist in the pre-industrial atmosphere. All of these increases
contribute to an enhanced greenhouse effect.

*Step 4:* Radiative forcing is a useful diagnostic and can easily be
calculated

Lessons from simple toy
models<http://www.realclimate.org/index.php/archives/2007/04/learning-from-a-simple-model>and
experience with more sophisticated GCMs suggests that any perturbation
to the TOA radiation budget *from whatever source* is a pretty good
predictor of eventual surface temperature change. Thus if the sun were to
become stronger by about 2%, the TOA radiation balance would change by
0.02*1366*0.7/4 = 4.8 W/m2 (taking albedo and geometry into account) and
this would be the radiative forcing (RF). An increase in greenhouse
absorbers or a change in the albedo have analogous impacts on the TOA
balance. However, calculation of the radiative forcing is again a job for
the line-by-line codes that take into account atmospheric profiles of
temperature, water vapour and aerosols. The most up-to-date calculations for
the trace gases are by Myhre et al
(1998)<http://www.agu.org/pubs/crossref/1998/98GL01908.shtml>and those
are the ones used in IPCC TAR and AR4.

These calculations can be condensed into simplified fits to the data, such
as the oft-used formula for CO2: RF = 5.35 ln(CO2/CO2_orig) (see Table
6.2<http://www.grida.no/climate/ipcc_tar/wg1/222.htm#635>in IPCC TAR
for the others). The logarithmic form comes from the fact that
some particular lines are already saturated and that the increase in forcing
depends on the ‘wings’ (see this
post<http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument-part-ii/>for
more details). Forcings for lower concentration gases (such as CFCs)
are
linear in concentration. The calculations in Myhre et al use representative
profiles for different latitudes, but different assumptions about clouds,
their properties and the spatial heterogeneity mean that the global mean
forcing is uncertain by about 10%. Thus the RF for a doubling of CO2 is
likely 3.7±0.4 W/m2 – the same order of magnitude as an increase of solar
forcing by 2%.

There are a couple of small twists on the radiative forcing concept. One is
that CO2 has an important role in the stratospheric radiation balance. The
stratosphere reacts very quickly to changes in that balance and that changes
the TOA forcing by a small but non-negligible amount. The surface response,
which is much slower, therefore reacts more proportionately to the
‘adjusted’ forcing and this is generally what is used in lieu of the
instantaneous forcing. The other wrinkle is depending slightly on the
spatial distribution of forcing agents, different feedbacks and processes
might come into play and thus an equivalent forcing from two different
sources might not give the same response. The factor that quantifies this
effect is called the ‘efficacy’ of the forcing, which for the most part is
reasonably close to one, and so doesn’t change the zeroth-order picture (Hansen
et al, 2005) <http://pubs.giss.nasa.gov/abstracts/2005/Hansen_etal_2.html>.
This means that climate forcings can be simply added to approximate the net
effect.

The total forcing from the trace greenhouse gases mentioned in Step 3, is
currently about 2.5 W/m2, and the net forcing (including cooling impacts of
aerosols and natural changes) is 1.6±1.0 W/m2 since the pre-industrial. Most
of the uncertainty is related to aerosol effects. Current growth in forcings
is dominated by increasing CO2, with potentially a small role for decreases
in reflective aerosols (sulphates, particularly in the US and EU) and
increases in absorbing aerosols (like soot, particularly from India and
China and from biomass burning).

*Step 5:* Climate sensitivity is around 3ºC for a doubling of CO2

The climate sensitivity classically defined is the response of global mean
temperature to a forcing once all the ‘fast feedbacks’ have occurred
(atmospheric temperatures, clouds, water vapour, winds, snow, sea ice etc.),
but before any of the ’slow’ feedbacks have kicked in (ice sheets,
vegetation, carbon cycle etc.). Given that it doesn’t matter much which
forcing is changing, sensitivity can be assessed from any particular period
in the past where the changes in forcing are known and the corresponding
equilibrium temperature change can be estimated. As we have discussed
previously<http://www.realclimate.org/index.php/archives/2004/12/index/#ClimateSensitivity>,
the last glacial period is a good example of a large forcing (~7 W/m2 from
ice sheets, greenhouse gases, dust and vegetation) giving a large
temperature response (~5 ºC) and implying a sensitivity of about 3ºC (with
substantial error bars). More formally, you can combine this estimate with
others taken from the 20th century, the response to volcanoes, the last
millennium, remote sensing etc. to get pretty good constraints on what the
number should be. This was done by Annan and Hargreaves
(2006)<http://www.realclimate.org/index.php/archives/2006/03/climate-sensitivity-plus-a-change/>,
and they come up with, you guessed it, 3ºC.

Converting the estimate for doubled CO2 to a more useful factor gives ~0.75
ºC/(W/m2).

*Step 6:* Radiative forcing x climate sensitivity is a significant number

Current forcings (1.6 W/m2) x 0.75 ºC/(W/m2) imply 1.2 ºC that would occur
at equilibrium. Because the oceans take time to warm up, we are not yet
there (so far we have experienced 0.7ºC), and so the remaining 0.5 ºC is ‘in
the pipeline’. We can estimate this independently using the changes in ocean
heat content over the last decade or so (roughly equal to the current
radiative imbalance) of ~0.7 W/m2, implying that this ‘unrealised’ forcing
will lead to another 0.7×0.75 ºC – i.e. 0.5 ºC.

W/m2 and therefore additional warming (at equilibrium) would be 2 to 5 ºC.
That is significant.

On Wed, Dec 2, 2009 at 3:10 PM, Don Winterstein <dfwinterstein@msn.com>wrote:

> "What would turn me from skeptic to believer?" I asked myself. Simple:
> Give all the raw climate data to scientists in a related geoscience field
> and get them to process and interpret the data so as to see whether there's
> an interpretation that shows effects from greenhouse gases to be relatively
> mild. If they can't do it, and they conclude that GHG release is indeed a
> serious problem, I'd be well on my way to believing.
>
> The ideal people to undertake such a study already exist in large numbers:
> the thousands of oil company geophysicists and geologists.
> Requirements: they would need: familiarity with scientific research methods,
> meaning they should have PhDs;
> to have recorded, processed
> and/or interpreted real Earth data;
> a minimum of 7 years'
> geoscience experience;
> to come highly recommended for
> their scientific accomplishments;
> experience with
> modeling geoscience data;
> familarity with the data of
> historical geology;
> an eagerness to participate in
> such project;
> support from government or oil
> company;
> no possibility of getting
> post-project grant money to further their climate research for at least 3
> years;
> to have no history of trying to
> alarm people about impending disasters from GHG.
>
> You will say, "These people will tend to be biased against finding a hazard
> from GHG!" Exactly. That's the kind of bias needed to counter the
> prevailing biases. As scientists they will be no more likely (and possibly
> less so) to cheat with the data than the climate scientists we're all
> familiar with--those who prosper by persuading people to give them money,
> where alarmism is a most effective method of persuasion.
>
> Major oil companies worldwide would likely be more than willing to provide
> and support some of their best researchers for such a project.
>
> Before world governments traumatize their economies by requiring huge cuts
> in GHG emissions, it would seem imperative to invest five years or so in a
> project of this sort. Best of all, it could remove my skepticism. : )
>
> Don
>
>
>
> ----- Original Message -----
> *From:* Don Winterstein <dfwinterstein@msn.com>
> *To:* Iain Strachan <igd.strachan@gmail.com>
> *Cc:* AmericanScientificAffiliation <asa@calvin.edu>
> *Sent:* Wednesday, December 02, 2009 12:33 AM
> *Subject:* Re: [asa] Phil Jones Stepping Down..
>
> It's true that few people would like to see the planet destroyed for
> human habitation. (There'll always be some.)
>
> However, I recall instances where certain ardent supporters of AGW seemed
> to want to attribute adverse weather phenomena to AGW, and I've sensed their
> disappointment when, for example, large portions of this country (if not the
> whole thing) were cooler than usual for much of this year. That is, there
> seems to be a desire among some to point to actual weather conditions as
> "proof" that the models are on track. Support for AGW predictions would
> surely go up if people could actually *feel* the world getting warmer
>
> So I suspect not a few ardent AGW supporters would like to see dramatic bad
> effects of GW. Then they'd be able to rub their skeptical friends' noses in
> them.
>
> As a former Earth scientist I remain skeptical about the significance of
> the "A" in AGW. The hacked/whistle-blown emails increase my
> skepticism. Apart from them, my skepticism has two primary sources:
> (1) Earth is extremely complicated and messy, very difficult to predict in
> any detail, and the data are often messy. I get that from my experience as
> a scientist. (2) The issue has been and still is extremely political, and
> many of the scientists involved are obviously political. I simply don't
> trust scientists who have obvious political motives connected to their field
> of investigation.
>
> My experience with some national lab scientists leads me to predict how
> this email investigation will turn out: The email authors will be busy
> concocting stories to "explain" their comments, they'll get buy-in from all
> their friends, everything will turn out to have been as innocent as newly
> fallen snow. That's how things work in the real world. --That is, unless
> they get an adversary involved who's really feisty, smart and tough. What
> are the chances?
>
> Don
>
>
> ----- Original Message -----
> *From:* Iain Strachan <igd.strachan@gmail.com>
> *To:* John Walley <john_walley@yahoo.com>
> *Cc:* Rich Blinne <rich.blinne@gmail.com> ; AmericanScientificAffiliation<asa@calvin.edu>
> *Sent:* Tuesday, December 01, 2009 11:35 PM
> *Subject:* Re: [asa] Phil Jones Stepping Down..
>
>
>
> On Wed, Dec 2, 2009 at 1:01 AM, John Walley <john_walley@yahoo.com> wrote:
>
>>
>> This doesn't address the comments of manipulating the peer review process
>> and all the incriminating comments in the code.
>>
>> I am sure the faithful will find solace in it but judging from the fallout
>> so far, I would say that most of the public are not buying this.
>>
>
>
> How many more times is it necessary to say this? NO-ONE finds "solace" in
> the thought that the planet is going to rack and ruin!!! What a ridiculous
> suggestion! I found solace in your original post, because on reading it
> hastily I thought that maybe there was some hope AGW wasn't true. But when
> I saw through it the whole thing began to have an unpleasant smell. When I
> saw that it was most likely the result of cherry picking the juicy bits by
> taking them out of context it didn't seem to offer so much false hope.
>
> Iain
>
>
>
>>
>> I would say its been a bad week for AGW.
>>
>> John
>>
>>
>>
>>
>> ------------------------------
>> *From:* Rich Blinne <rich.blinne@gmail.com>
>> *To:* John Walley <john_walley@yahoo.com>
>> *Cc:* AmericanScientificAffiliation <asa@calvin.edu>
>> *Sent:* Tue, December 1, 2009 7:17:40 PM
>> *Subject:* Re: [asa] Phil Jones Stepping Down..
>>
>>
>>
>> On Tue, Dec 1, 2009 at 4:54 PM, John Walley <john_walley@yahoo.com>wrote:
>>
>>> Climate scientist at center of e-mail controversy to step down
>>>
>>> By Juliet Eilperin
>>> Washington Post Staff Writer
>>> Tuesday, December 1, 2009 3:45 PM
>>>
>>>
>>> A scientist who is one of the central figures in the controversy over
>>> hacked e-mails from the University of East Anglia's Climate Research Unit
>>> announced Tuesday that he is stepping down while the university investigates
>>> the incident.
>>>
>>> Climate skeptics have seized on several e-mails from Phil Jones, director
>>> of the university's Climatic Research Unit, to other researchers as evidence
>>> that prominent scientists have sought to silence their voice in the debate
>>> over global warming. The e-mails were pirated and posted online last month.
>>>
>>> "What is most important is that CRU continues its world leading research
>>> with as little interruption and diversion as possible," Jones said in a
>>> statement. "After a good deal of consideration I have decided that the best
>>> way to achieve this is by stepping aside from the Director's role during the
>>> course of the independent review and am grateful to the University for
>>> agreeing to this. The Review process will have my full support."
>>>
>>> East Anglia's Vice-Chancellor Professor Edward Acton said he had
>>> "accepted Professor Jones's offer to stand aside during this period. It is
>>> an important step to ensure that CRU can continue to operate normally and
>>> the independent review can conduct its work into the allegations."
>>>
>>> Action added the university will disclose details of the probe, including
>>> who will head it and how long it will last "within days."
>>> Marc Morano, who edits the climate skeptic blog, ClimateDepot.com,
>>> welcomed the news with an e-mail stating, "One Down: ClimateGate Scientist
>>> Phil Jones to temporarily step down... 'pending investigation into
>>> allegations that he overstated case for man-made climate change.'"
>>>
>>>
>>>
>>>
>>>
>>> To unsubscribe, send a message to majordomo@calvin.edu with
>>> "unsubscribe asa" (no quotes) as the body of the message.
>>>
>>
>>
>> From the UEA:
>>
>>
>> CRU Update 1 December
>>
>> Professor Phil Jones has today announced that he will stand aside as
>> Director of the Climatic Research Unit until the completion of an
>> independent Review resulting from allegations following the hacking and
>> publication of emails from the Unit.
>>
>> Professor Jones said: "What is most important is that CRU continues its
>> world leading research with as little interruption and diversion as
>> possible. After a good deal of consideration I have decided that the best
>> way to achieve this is by stepping aside from the Director's role during the
>> course of the independent review and am grateful to the University for
>> agreeing to this. The Review process will have my full support."
>>
>> Vice-Chancellor Professor Edward Acton said: "I have accepted Professor
>> Jones's offer to stand aside during this period. It is an important step to
>> ensure that CRU can continue to operate normally and the independent review
>> can conduct its work into the allegations.
>>
>> “We will announce details of the Independent Review, including its terms
>> of reference, timescale and the chair, within days. I am delighted that
>> Professor Peter Liss, FRS, CBE, will become acting director.”
>> *
>>
>> The University of East Anglia has previously released the following press
>> release and statements from Prof Trevor Davies, Pro-Vice-Chancellor for
>> Research, Prof Phil Jones, head of the Climatic Research Unit, and from CRU.
>>
>> CRU climate data already ‘over 95%’ available*
>>
>> Over 95% of the CRU climate data set concerning land surface temperatures
>> has been accessible to climate researchers, sceptics and the public for
>> several years the University of East Anglia has confirmed.
>>
>> “It is well known within the scientific community and particularly those
>> who are sceptical of climate change that over 95% of the raw station data
>> has been accessible through the Global Historical Climatology Network for
>> several years. We are quite clearly not hiding information which seems to
>> be the speculation on some blogs and by some media commentators,” commented
>> the University’s Pro-Vice-Chancellor, Research Enterprise and Engagement
>> Professor Trevor Davies.
>>
>> The University will make all the data accessible as soon as they are
>> released from a range of non-publication agreements. Publication will be
>> carried out in collaboration with the Met Office Hadley Centre.
>>
>> The procedure for releasing these data, which are mainly owned by National
>> Meteorological Services (NMSs) around the globe, is by direct contact
>> between the permanent representatives of NMSs (in the UK the Met Office).
>>
>> “We are grateful for the necessary support of the Met Office in requesting
>> the permissions for releasing the information but understand that responses
>> may take several months and that some countries may refuse permission due to
>> the economic value of the data,” continued Professor Davies.
>>
>> The remaining data, to be published when permissions are given, generally
>> cover areas of the world where there are fewer data collection stations.
>>
>> “CRU’s full data will be published in the interests of research
>> transparency when we have the necessary agreements. It is worth reiterating
>> that our conclusions correlate well to those of other scientists based on
>> the separate data sets held by the National Oceanic and Atmospheric
>> Administration (NOAA) and the NASA Goddard Institute for Space Studies
>> (GISS),” concluded Professor Davies.
>> *
>>
>> Statement from Professor Trevor Davies, Pro-Vice-Chancellor, Research*
>>
>> The publication of a selection of the emails and data stolen from the
>> Climatic Research Unit (CRU) has led to some questioning of the climate
>> science research published by CRU and others. There is nothing in the stolen
>> material which indicates that peer-reviewed publications by CRU, and others,
>> on the nature of global warming and related climate change are not of the
>> highest-quality of scientific investigation and interpretation. CRU’s
>> peer-reviewed publications are consistent with, and have contributed to, the
>> overwhelming scientific consensus that the climate is being strongly
>> influenced by human activity. The interactions of the atmosphere, oceans,
>> land, and ice mean that the strongly-increasing concentrations of greenhouse
>> gases in the atmosphere do not produce a uniform year-on-year increase in
>> global temperature. On time-scales of 5-10 years, however, there is a broad
>> scientific consensus that the Earth will continue to warm, with attendant
>> changes in the climate, for the foreseeable future. It is important, for all
>> countries, that this warming is slowed down, through substantial reductions
>> in greenhouse gas emissions to reduce the most dangerous impacts of climate
>> change. Respected international research groups, using other data sets, have
>> come to the same conclusion.
>>
>> The University of East Anglia and CRU are committed to scientific
>> integrity, open debate and enhancing understanding. This includes a
>> commitment to the international peer-review system upon which progress in
>> science relies. It is this tried and tested system which has underpinned the
>> assessments of the Intergovernmental Panel on Climate Change. It is through
>> that process that we can engage in respectful and informed debate with
>> scientists whose analyses appear not to be consistent with the current
>> overwhelming consensus on climate change
>>
>> The publication of a selection of stolen data is the latest example of a
>> sustained and, in some instances, a vexatious campaign which may have been
>> designed to distract from reasoned debate about the nature of the urgent
>> action which world governments must consider to mitigate, and adapt to,
>> climate change. We are committed to furthering this debate despite being
>> faced with difficult circumstances related to a criminal breach of our
>> security systems and our concern to protect colleagues from the more extreme
>> behaviour of some who have responded in irrational and unpleasant ways to
>> the publication of personal information.
>>
>> There has been understandable interest in the progress and outcome of the
>> numerous requests under information legislation for large numbers of the
>> data series held by CRU. The University takes its responsibilities under the
>> Freedom of Information Act 2000, Environmental Information Regulations 2004,
>> and the Data Protection Act 1998 very seriously and has, in all cases,
>> handled and responded to requests in accordance with its obligations under
>> each particular piece of legislation. Where appropriate, we have consulted
>> with the Information Commissioners Office and have followed their advice.
>>
>> In relation to the specific requests at issue here, we have handled and
>> responded to each request in a consistent manner in compliance with the
>> appropriate legislation. No record has been deleted, altered, or otherwise
>> dealt with in any fashion with the intent of preventing the disclosure of
>> all, or any part, of the requested information. Where information has not
>> been disclosed, we have done so in accordance with the provisions of the
>> relevant legislation and have so informed the requester.
>>
>> The Climatic Research Unit holds many data series, provided to the Unit
>> over a period of several decades, from a number of nationally-funded
>> institutions and other research organisations around the world, with
>> specific agreements made over restrictions in the dissemination of those
>> original data. All of these individual series have been used in CRU’s
>> analyses. It is a time-consuming process to attempt to gain approval from
>> these organisations to release the data. Since some of them were provided
>> decades ago, it has sometimes been necessary to track down the successors of
>> the original organisations. It is clearly in the public interest that these
>> data are released once we have succeeded in gaining the approval of
>> collaborators. Some who have requested the data will have been aware of the
>> scale of the exercise we have had to undertake. Much of these data are
>> already available from the websites of the Global Historical Climate Data
>> Network and the Goddard Institute for Space Science.
>>
>> Given the degree to which we collaborate with other organisations around
>> the world, there is also an understandable interest in the computer security
>> systems we have in place in CRU and UEA. Although we were confident that our
>> systems were appropriate, experience has shown that determined and skilled
>> people, who are prepared to engage in criminal activity, can sometimes hack
>> into apparently secure systems. Highly-protected government organisations
>> around the world have also learned this to their cost.
>>
>> We have, therefore, decided to conduct an independent review, which will
>> address the issue of data security, an assessment of how we responded to a
>> deluge of Freedom of Information requests, and any other relevant issues
>>
>> *Statement from Professor Phil Jones, Head of the Climatic Research Unit,
>> University of East Anglia.
>>
>> *In the frenzy of the past few days, the most vital issue is being
>> overshadowed: we face enormous challenges ahead if we are to continue to
>> live on this planet.
>>
>> One has to wonder if it is a coincidence that this email correspondence
>> has been stolen and published at this time. This may be a concerted attempt
>> to put a question mark over the science of climate change in the run-up to
>> the Copenhagen talks.
>>
>> That the world is warming is based on a range of sources: not only
>> temperature records but other indicators such as sea level rise, glacier
>> retreat and less Arctic sea ice.
>>
>> Our global temperature series tallies with those of other, completely
>> independent, groups of scientists working for NASA and the National Climate
>> Data Center in the United States, among others. Even if you were to ignore
>> our findings, theirs show the same results. The facts speak for themselves;
>> there is no need for anyone to manipulate them.
>>
>> We have been bombarded by Freedom of Information requests to release the
>> temperature data that are provided to us by meteorological services around
>> the world via a large network of weather stations. This information is not
>> ours to give without the permission of the meteorological services involved.
>> We have responded to these Freedom of Information requests appropriately and
>> with the knowledge and guidance of the Information Commissioner.
>>
>> We have stated that we hope to gain permission from each of these services
>> to publish their data in the future and we are in the process of doing so.
>>
>> My colleagues and I accept that some of the published emails do not read
>> well. I regret any upset or confusion caused as a result. Some were clearly
>> written in the heat of the moment, others use colloquialisms frequently used
>> between close colleagues.
>>
>> We are, and have always been, scrupulous in ensuring that our science
>> publications are robust and honest.
>>
>> *CRU statement*
>>
>> Recently thousands of files and emails illegally obtained from a research
>> server at the University of East Anglia (UEA) have been posted on various
>> sites on the web. The emails relate to messages received or sent by the
>> Climatic Research Unit (CRU) over the period 1996-2009.
>>
>> A selection of these emails have been taken out of context and
>> misinterpreted as evidence that CRU has manipulated climate data to present
>> an unrealistic picture of global warming.
>>
>> This conclusion is entirely unfounded and the evidence from CRU research
>> is entirely consistent with independent evidence assembled by various
>> research groups around the world.
>>
>> There is excellent agreement on the course of temperature change since
>> 1881 between the data set that we contribute to (HadCRUT3) and two other,
>> independent analyses of worldwide temperature measurements. There are no
>> statistically significant differences between the warming trends in the
>> three series since the start of the 20th century. The three independent
>> global temperature data series have been assembled by:
>>
>> • CRU and the Met Office Hadley Centre (HadCRUT3) in the UK.
>> • The National Climatic Data Center (NCDC) of the National Oceanographic
>> and Atmospheric Administration (NOAA) in Asheville, NC, USA.
>> • The Goddard Institute of Space Studies (GISS), part of the National
>> Aeronautic and Space Administration (NASA) in New York.
>>
>> The warming shown by the HadCRUT3 series between the averages of the two
>> periods (1850-99 and 2001-2005) was 0.76±0.19°C, and this is corroborated by
>> the other two data sets.
>>
>> The Intergovernmental Panel on Climate Change (IPCC) in its 4th Assessment
>> Report (AR4) published in 2007 concluded that the warming of the climate
>> system was unequivocal. This conclusion was based not only on the
>> observational temperature record, although this is the key piece of
>> evidence, but on multiple strands of evidence. These factors include:
>> long-term retreat of glaciers in most alpine regions of the world;
>> reductions in the area of the Northern Hemisphere (NH) snow cover during the
>> spring season; reductions in the length of the freeze season in many NH
>> rivers and lakes; reduction in Arctic sea-ice extent in all seasons, but
>> especially in the summer; increases in global average sea level since the
>> 19th century; increases in the heat content of the ocean and warming of
>> temperatures in the lower part of the atmosphere since the late 1950s.
>>
>> CRU has also been involved in reconstructions of temperature (primarily
>> for the Northern Hemisphere) from proxy data (non-instrumental sources such
>> as tree rings, ice cores, corals and documentary records). Similar
>> temperature reconstructions have been developed by numerous other groups
>> around the world. The level of uncertainty in this indirect evidence for
>> temperature change is much greater than for the picture of temperature
>> change shown by the instrumental data. But different reconstructions of
>> temperature change over a longer period, produced by different researchers
>> using different methods, show essentially the same picture of highly unusual
>> warmth across the NH during the 20th century. The principal conclusion from
>> these studies (summarized in IPCC AR4) is that the second half of the 20th
>> century was very likely (90% probable) warmer than any other 50-year period
>> in the last 500 years and likely (66% probable) the warmest in the past 1300
>> years.
>>
>> One particular, illegally obtained, email relates to the preparation of a
>> figure for the WMO Statement on the Status of the Global Climate in 1999.
>> This email referred to a “trick” of adding recent instrumental data to the
>> end of temperature reconstructions that were based on proxy data. The
>> requirement for the WMO Statement was for up-to-date evidence showing how
>> temperatures may have changed over the last 1000 years. To produce
>> temperature series that were completely up-to-date (i.e. through to 1999) it
>> was necessary to combine the temperature reconstructions with the
>> instrumental record, because the temperature reconstructions from proxy data
>> ended many years earlier whereas the instrumental record is updated every
>> month. The use of the word “trick” was not intended to imply any deception.
>>
>> Phil Jones comments further: “One of the three temperature reconstructions
>> was based entirely on a particular set of tree-ring data that shows a strong
>> correlation with temperature from the 19th century through to the mid-20th
>> century, but does not show a realistic trend of temperature after 1960. This
>> is well known and is called the ‘decline’ or ‘divergence’. The use of the
>> term ‘hiding the decline’ was in an email written in haste. CRU has not
>> sought to hide the decline. Indeed, CRU has published a number of articles
>> that both illustrate, and discuss the implications of, this recent tree-ring
>> decline, including the article that is listed in the legend of the WMO
>> Statement figure. It is because of this trend in these tree-ring data that
>> we know does not represent temperature change that I only show this series
>> up to 1960 in the WMO Statement.”
>>
>> The ‘decline’ in this set of tree-ring data should not be taken to mean
>> that there is any problem with the instrumental temperature data. As for the
>> tree-ring decline, various manifestations of this phenomenon have been
>> discussed by numerous authors, and its implications are clearly signposted
>> in Chapter 6 of the IPCC AR4 report.
>>
>> Included here is a copy of the figure used in the WMO statement, together
>> with an alternative version where the climate reconstructions and the
>> instrumental temperatures are shown separately.
>>
>> Rich Blinne
>>
>> Member ASA
>>
>>
>
>
> --
> -----------
> Non timeo sed caveo
>
>

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Received on Wed Dec 2 17:37:26 2009

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