🚀 go-pugleaf

On Sun, 31 Oct 2010 15:33:21 +1100, Oy rool out a carbon tax
<gillard_lies@nowhere.com> wrote:


>>> The AGWers were initially blessed with the fortune of increasing
>>> temperatures to support (not prove) their hypothesis. Since that time
>>> they have been at great pains to cling to their mantra, as temperatures
>>> fail to follow the cataclysmic trajectory their "science" predicts.
>>>
>> 
>> On the contrary:
>> 

<snip>

>
>No. Not "on the contrary". If that were the case, why would Kevin
>Trenberth, head of the Climate Analysis Section at the National Center
>for Atmospheric Research, say to Michael Mann, the director of the Earth
>System Science Center at 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".
>
http://www.skepticalscience.com/Kevin-Trenberth-travesty-cant-account-for-the-lack-of-warming.htm

<Start extract>

Trenberth's views are clarified in the paper "An imperative for
climate change planning: tracking Earth's global energy". We know the
planet is continually heating due to increasing carbon dioxide but
that surface temperature sometimes have short term cooling periods.
This is due to internal variability and Trenberth was lamenting that
our observation systems can't comprehensively track all the energy
flow through the climate system.

This has been most commonly interpreted (among skeptics) as climate
scientists secretly admitting amongst themselves that global warming
really has stopped. Is this what Trenberth is saying? If one takes a
little time to understand the science that Trenberth is discussing,
his meaning becomes clear.

If you read the full email, you learn that Trenberth is actually
informing fellow climate scientists about a paper he'd recently
published, An imperative for climate change planning: tracking Earth's
global energy (Trenberth 2009). The paper discusses the planet's
energy budget - how much net energy is flowing into our climate and
where it's going. It also discusses the systems we have in place to
track energy flow in and out of our climate system.

Trenberth states unequivocally that our planet is continually heating
due to increasing carbon dioxide. This energy imbalance was very small
40 years ago but has steadily increased to around 0.9 W/m^2 over the
2000 to 2005 period, as observed by satellites. Preliminary satellite
data indicates the energy imbalance has continued to increase from
2006 to 2008. The net result is that the planet is continuously
accumulating heat. Global warming is still happening.

Next, Trenberth wonders with this ever increasing heat, why doesn't
surface temperature continuously rise? The standard answer is "natural
variability". But such a general answer doesn't explain the actual
physical processes involved. If the planet is accumulating heat, the
energy must go somewhere. Is it going into melting ice? Is it being
sequestered deep in the ocean? Did the 2008 La Nina rearrange the
configuration of ocean heat? Is it all of the above? Trenberth wants
answers!

So like an obsessive accountant, Trenberth pores over the energy
budget, tallying up the joules accumulating in various parts of the
climate. A global energy imbalance of 0.9 W/m^2 means the planet is
accumulating 145 x 10^20 joules per year. The following list gives the
amount of energy going into various parts of the climate over the 2004
to 2008 period:

    *
      Land:   2 x  10^20 joules per year
    *
      Arctic sea Ice:   1 x 10^20 joules per year
    *
      Ice sheets:   1.4 x 10^20 joules per year
    *
      Total land ice:   between 2 to 3 x 10^20 joules per year
    *
      Ocean:   between 20 to 95 x 10^20 joules per year
    *
      Sun:   16 x 10^20 joules per year (eg - the sun has been cooling from 2004 to 2008)

These various contributions total between 45 to 115 x 10^20 joules per
year. This falls well short of the total 145 x 10^20 joules per year
(although the error bars do overlap). Trenberth expresses frustration
that observation systems are inadequate to track the flow of energy.
It's not that global warming has stopped. We know global warming has
continued because satellites find an energy imbalance. It's that our
observation systems need to be more accurate in tracking the energy
flows through our climate and closing the energy budget.

So what may be causing the discrepancy? As the ocean heat data only
goes to 900 metre depth, Trenberth suggests that perhaps heat is being
sequestered below 900 metres. There is support for this idea in a
later paper von Schuckmann 2009. This paper uses Argo buoy data to
calculate ocean heat down to 2000 metres depth. From 2003 to 2008, the
world's oceans have been accumulating heat at a rate of 0.77 W/m^2.
This higher trend for ocean heat would bring the total energy build-up
more in line with satellite measurements of net energy imbalance.
However, von Schuckmann's results were published after Trenberth's
paper so I look forward to seeing how this plays out in future papers.

So to summarise, Trenberth's email says this:

"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." 

After reviewing the discussion in Trenberth 2009, it's apparent that
what he meant was this:

"Global warming is still happening - our planet is still accumulating
heat. But our observation systems aren't able to comprehensively keep
track of where all the energy is going. Consequently, we can't
definitively explain why surface temperatures have gone down in the
last few years. That's a travesty!"

Skeptics use Trenberth's email to characterise climate scientists as
secretive and deceptive. However, when one takes the trouble to
acquaint oneself with the science, the opposite becomes apparent.
Trenberth outlines his views in a clear, open manner, frankly
articulating his frustrations at the limitations of observation
systems. Trenberth's opinions didn't need to be illegally stolen and
leaked onto the internet. They were already publicly available in the
peer reviewed literature - and much less open to misinterpretation
than a quote-mined email.

<End extract>