image
Physics Forums Logo
image
image
* Register * Upgrade Blogs Library Staff Rules Mark Forums Read
image
image   image
image

Go Back   Physics Forums > Other Sciences > Earth


Closed Thread

image Climate Science Update Share It Thread Tools Search this Thread image
Old Nov27-09, 08:59 AM       Last edited by Xnn; Nov27-09 at 07:53 PM.. Reason: Spelling            #1
Xnn

Xnn is Offline:
Posts: 485
Blog Entries: 2
Climate Science Update

Science marches on.

The current physical science basis for climate change was based on
peer reviewed literature available in 2006. Since that time,
there have been a number of newer studies that have contributed
to a better understanding. These have been put together into a
new report for the meeting in Copenhagen.

In general, uncertainties resolved since 2006 point to a more
rapidly changing and more sensitive climate than previously thought.
There are several interesting sections in the report with lots of vivid
color photos. However, overall it is a sombering report.
CO2 emissions are accelerating while temperatures, sea level and
water cycle increases are all expected to accelerate.
It's very difficult to conceive the climate tracking anything but
the upper end of the projections.

Here are highlights from the new report:

Global carbon dioxide (CO2) emissions from fossil fuel burning in 2008 were 40%
higher than those in 1990, with a three-fold acceleration over the past 18 years.

Global CO2 emissions from fossil fuel burning are tracking near the highest scenarios
considered so far by the IPCC.

The fraction of CO2 emissions absorbed by the land and ocean CO2 reservoirs has likely
decreased by ~5% (from 60 to 55%) in the past 50 years, though interannual variability is
large.

Global air temperature, humidity and rainfall trend patterns exhibit a distinct fingerprint
that cannot be explained by phenomena apart from increased atmospheric greenhouse gas
concentrations.

Every year this century (2001-2008) has been among the top 10 warmest years since
instrumental records began, despite solar irradiance being relatively weak over the past few
years.

Global atmospheric temperatures maintain a strong warming trend since the 1970s
(~0.6°C), consistent with expectations of greenhouse induced warming.

Increases in hot extremes and decreases in cold extremes have continued and are expected
to amplify further.

Ice-shelves connect continental ice-sheets to the ocean. Destabilization of ice-shelves
along the Antarctic Peninsula has been widespread with 7 collapses over the past 20 years.

Signs of ice shelf weakening have been observed elsewhere than in the Antarctic Peninsula,
e.g. in the Bellingshausen and Amundsen seas, indicating a more widespread influence of
atmospheric and oceanic warming than previously thought.

There is a strong influence of ocean warming on ice sheet stability and mass balance via the
melting of ice-shelves. Anthropogenic climate change is expected to lead to further increases
in precipitation extremes, both increases in heavy precipitation and increases in drought.

Although future changes in tropical cyclone activity cannot yet be modeled, new analyses
of observational data confirm that the intensity of tropical cyclones has increased in the
past three decades in line with rising tropical ocean temperatures.

There is widespread evidence of increased melting of glaciers and ice-caps since the mid
1990s.

The contribution of glaciers and ice-caps to global sea-level has increased from 0.8
millimeters per year in the 1990s to be 1.2 millimeters per year today.

The adjustment of glaciers and ice caps to present climate alone is expected to raise sea
level by ~18 centimeters. Under warming conditions they may contribute as much as ~55
centimeters by 2100

The surface area of the Greenland ice sheet which experiences summer melt has increased
by 30% since 1979, consistent with warming air temperatures. Melt covered 50% of the ice
sheet during the record season in 2007.

The net loss of ice from the Greenland ice sheet has accelerated since the mid-1990s and is
now contributing as much as 0.7 millimeters per year to sea level rise due to both increased
melting and accelerated ice flow.

Antarctica is also losing ice mass at an increasing rate, mostly from the West Antarctic ice
sheet due to increased ice flow. Antarctica is currently contributing to sea level rise at a
rate nearly equal to Greenland.

The observed summer-time melting of Arctic sea-ice has far exceeded the worst-case
projections from climate models of IPCC AR4.

The warming commitment associated with existing atmospheric greenhouse gas levels means
it is very likely that in the coming decades the summer Arctic Ocean will become ice-free,
although the precise timing of this remains uncertain.

Satellite observations show a small increase of Antarctic sea-ice extent and changes to
seasonality, although there is considerable regional variability. This is most likely due to
changes in Southern Ocean winds associated with stratospheric ozone-depletion.

Estimates of ocean heat uptake have converged and are found to be 50% higher than
previous calculations.

Global ocean surface temperature reached the warmest ever recorded for each of June, July
and August 2009.

Ocean acidification and ocean de-oxygenation have been identified as potentially
devastating for large parts of the marine ecosystem.

Satellite measurements show sea-level is rising at 3.4 millimeters per year since these
records began in 1993. This is 80% faster than the best estimate of the IPCC Third
Assessment Report for the same time period.

Accounting for ice-sheet mass loss, sea-level rise until 2100 is likely to be at least twice as
large as that presented by IPCC AR4, with an upper limit of ~2m based on new ice-sheet
understanding.

There are several elements in the climate system that could pass a tipping point this century
due to human activities, leading to abrupt and/or irreversible change.

1 °C global warming (above 1980-1999) carries moderately significant risks of passing large
scale tipping points, and 3 °C global warming would give substantial or severe risks.

There are prospects for early warning of approaching tipping points, but if we wait until a
transition begins to be observed, in some cases it would be unstoppable.

The full report is available here:

http://www.copenhagendiagnosis.com/default.html

Link directly to pdf file:

http://www.ccrc.unsw.edu.au/Copenhag...gnosis_LOW.pdf
 
Old Nov27-09, 09:31 AM                  #2
vanesch

PF Mentor

vanesch is Offline:
Posts: 6,010
Re: Climate Science Update

I have to say I hate this kind of semi-scientific-political publi-brochure. This kind of stuff is exactly what makes people wary of climate science. This looks like an advertisement !
That doesn't mean that what's said in there is wrong, but I don't like the commercial way in which it is said.


Just some things on the surface that shock me:
From the first grey box, in fact the very first sentence of the report:
Global carbon dioxide (CO2) emissions from fossil fuel burning in 2008 were 40% higher
than those in 1990, with a three-fold acceleration over the past 18 years.
There is also:
CO2 levels increased at a rate of 1.9 ppm/year between
2000 and 2008, compared to 1.5 ppm/yr in the 1990s.
Now how does that rime with figure 2, where we see an almost linear rise of CO2 in the atmosphere since 1980 ?

It seems to me that especially alarming language is used here, as if one had to promote a certain product.
 
Old Nov27-09, 12:12 PM       Last edited by Sorry!; Nov27-09 at 07:48 PM..            #3
Sorry!

Sorry! is Offline:
Posts: 555
Re: Climate Science Update

Originally Posted by vanesch View Post
I have to say I hate this kind of semi-scientific-political publi-brochure. This kind of stuff is exactly what makes people wary of climate science. This looks like an advertisement !
That doesn't mean that what's said in there is wrong, but I don't like the commercial way in which it is said.


Just some things on the surface that shock me:
From the first grey box, in fact the very first sentence of the report:


There is also:


Now how does that rime with figure 2, where we see an almost linear rise of CO2 in the atmosphere since 1980 ?

It seems to me that especially alarming language is used here, as if one had to promote a certain product.
It is kinda of a weird way of them to promote their findings though (in a brochure) but we have to think about who this is trying to sway... the common person. This isn't really meant for scientists to use it's meant to be a political tool (which I admit isn't the best thing but nearly all science has political aspects, climate change just has more due to its seeming importance to the world)
 
Old Nov27-09, 07:00 PM                  #4
sylas
 
sylas's Avatar

sylas is Offline:
Posts: 1,434
Blog Entries: 5
Recognitions:
PF Contributor PF Contributor
Science Advisor Science Advisor
Re: Climate Science Update

Originally Posted by vanesch View Post
I have to say I hate this kind of semi-scientific-political publi-brochure. This kind of stuff is exactly what makes people wary of climate science. This looks like an advertisement !
That doesn't mean that what's said in there is wrong, but I don't like the commercial way in which it is said.
My reaction is completely the reverse. The problem with this whole area is that there is a lot of public interest and a lot of confusion.

If we were serious about simply following the scientific literature, then it would be pretty straight forward and you'd get conclusions pretty much like what is in this report.

However, the scientific literature is written primarily for a different audience. And although the science should be pursued independent of any policy considerations; the reverse is not the case; policy needs to take into account the best available scientific information on matters of relevance.

It follows that there is a need for scientists to communicate better, to a wider audience; not just the general public but governments and other policy makers. The IPCC reports are driven by this requirement.

The interaction between science and politics and policy, in any ideal world, should be like the following:
  • The conclusions reached by science need to be obtained without any deference to policy implications of the conclusions. Science ideally seeks answers and confidence limits on those answers based exclusively on what the evidence and research actually can show.
  • The questions and issues addressed by scientists, however, might well be driven by secondary requirements of what is deemed important to know, for policy reasons.

Precisely how we improve the communication of credible science is a good question; but anything you do along those lines should be in the way of providing accessible information.

I think this only looks like an advertisement because there is such a gaping disconnect between what is happening in the world of science and what is being debated in the political world. There are a heap of open questions in climate science and all kinds of large uncertainties. But they are not the same as the major uncertainties debated more widely.

The wider questions seem to be things like... is global warming real? is it caused by human activities?

The answers to those two questions are actually very straightforward. It's yes, and yes.

There are riders you can add, along the lines that everything in science is always in principle open to dispute and revision; but for an overview, the "yes" in both cases is about as strong as you can possibly get. The warming is measured. The importance of greenhouse effects is basic physics. And the association of that to human activities is unambiguous.

These answers don't rule out all other factors; but the strong warming trend of the latter half of the twentieth century in particular is solidly linked to atmospheric composition and a stronger greenhouse effect.

The relevant open scientific questions are about quantifying the warming trend, along with other effects, refining physical understanding to model it better (a never ending project of continual improvements) and sorting out things like the carbon cycle, the energy balance into the ocean, the feedbacks from cloud and weather and much else beside which bear upon the complex response of the climate system.

Originally Posted by vanesch View Post
Just some things on the surface that shock me:
From the first grey box, in fact the very first sentence of the report:
Global carbon dioxide (CO2) emissions from fossil fuel burning in 2008 were 40% higher than those in 1990, with a three-fold acceleration over the past 18 years.
There is also:
CO2 levels increased at a rate of 1.9 ppm/year between 2000 and 2008, compared to 1.5 ppm/yr in the 1990s.
Now how does that rime with figure 2, where we see an almost linear rise of CO2 in the atmosphere since 1980 ?

It seems to me that especially alarming language is used here, as if one had to promote a certain product.
I don't understand your objection here, frankly. The context of this report is a world that is looking at managing carbon emissions as a matter of policy to mitigate against the risks associated with larger changes in the atmospheric greenhouse effect. The report is promoting the need for managing emissions and noting that they are continuing to increase at levels that are right along the high end of the range of projections considered in the most recent IPCC report.

Figure 2 is completely consistent with the numbers given. The rate of increase IS increasing and you can see quite easily that the increase since 1980 is not linear. Just hold a ruler up against the graph if you want to check. Of course, the proper measure of linearity works from the numbers, not eyeballing a graph, and the numbers are as you have quoted from the report. What’s the problem?

There are a number of other sources that are attempting to address the gap between what is published in the literature and what is accessible to policy matters or interested members of the public. Not all of them are thoroughly grounded in the scientific literature or well reviewed by directly relevant scientific researchers. This one is, however; and stands as a good summary of technical material, thoroughly grounded in scientific literature, produced by a large group of some of the most active scientists researching on the directly relevant science, and with a high level of oversight and review. I think it stands as a useful resource for helping follow this whole topic.

Cheers -- sylas
 
Old Nov27-09, 07:35 PM       Last edited by sylas; Nov28-09 at 03:34 PM.. Reason: spelling. Diagnosis, not Disagnosis. (Thanks, Mark44!)            #5
sylas
 
sylas's Avatar

sylas is Offline:
Posts: 1,434
Blog Entries: 5
Recognitions:
PF Contributor PF Contributor
Science Advisor Science Advisor
A better link

By the way... the home page for this report
The Copenhagen Diagnosis
gives easy access to the full report at two resolution levels, an online version, background on the authors, background on the reasons for the report, and so on; which may help understand some of the background to why and how it was written.
 
Old Nov27-09, 08:22 PM                  #6
Xnn

Xnn is Offline:
Posts: 485
Blog Entries: 2
Re: Climate Science Update

From the report:
Global carbon dioxide (CO2) emissions from fossil fuel burning in 2008 were 40%
higher than those in 1990, with a three-fold acceleration over the past 18 years.

Global CO2 emissions from fossil fuel burning are tracking near the highest scenarios
considered so far by the IPCC.
Originally Posted by vanesch View Post
Now how does that rime with figure 2, where we see an almost linear rise of CO2 in the atmosphere since 1980 ?

It seems to me that especially alarming language is used here, as if one had to promote a certain product.
I agree that there is some alarming language in the report. However, the prospects
of significant reductions in emissions are fairly low. As the report points out, emissions
have only increased and I sense that the Climate Scientist that put the
report together are very concerned and frustrated. It's apparent that there
will be a significant climate shift over the next century.

Anyhow, I also struggle with reconciling the 3 fold acceleration in emissions
since 1990 while atmospheric CO2 concentrations have increased steadily
with only the slightest hint of an acceleration.

From the report:
The global rate of increase of fossil fuel CO2 emissions has accelerated
three-fold over the last 18 years, increasing from 1.0% per year in the 1990s to
3.4% per year between 2000-2008 (Figure 1). The accelerated growth in fossil
fuel CO2 emissions since 2000 was primarily caused by fast growth rates in developing
countries (particularly China) in part due to increased international trade of goods
(Peters and Hertwich 2008), and by the slowdown of previous improvements in the CO2
intensity of the global economy (Raupach et al. 2007). The observed acceleration in fossil fuel CO2 emissions is tracking high-end emissions scenarios used by IPCC AR4 (Nakicenovic et al. 2000).
The report does reviews CO2 sinks, but jumps rather abruptly to vulnerabilities.
What's obvious to me is that the sinks have increased almost as fast as emission
have grown. That is rather odd. Sinks ought to be operating in proportion to
atmospheric CO2 concentration, precipitation and winds.

There are 3 major sinks: Plants & soils, the deep ocean and sediments (rocks).
About 30% of CO2 emissions end up in plants and soils, 25% goes into the deep
ocean and <1% ends up in sediments.

The report makes the following statement concerning the deep oceans:

In the Southern Ocean, the CO2 sink has not increased since 1981
in spite of the large increase in atmospheric CO2 (Le Quéré et al. 2007;
Metzl 2009; Takahashi et al. 2009). The Southern Ocean trends have been
attributed to an increase in winds, itself a likely consequence of
ozone depletion (Lovenduski et al. 2008). Similarly, in the North
Atlantic, the CO2 sink decreased by ~50% since 1990 (Schuster
et al. 2009), though part of the decrease has been associated
with natural variability (Thomas et al. 2008).
So, I can only infer that plants and soils have been taking most all
of the slack; in other words there is some good news that may
have been overlooked.
 
Old Nov27-09, 09:07 PM       Last edited by sylas; Nov27-09 at 09:15 PM.. Reason: fixed a link; postscript            #7
sylas
 
sylas's Avatar

sylas is Offline:
Posts: 1,434
Blog Entries: 5
Recognitions:
PF Contributor PF Contributor
Science Advisor Science Advisor
Re: Climate Science Update

Originally Posted by Xnn View Post
Anyhow, I also struggle with reconciling the 3 fold acceleration in emissions
since 1990 while atmospheric CO2 concentrations have increased steadily
with only the slightest hint of an acceleration.
On the contrary. The rate of atmospheric CO2 increase has accelerated as emissions have accelerated. Remember to to look at the percentage change in the rate of increase; not merely the increase itself.

The major CO2 observatory is the NOAA monitoring station at Mauna Luo. It provides ready access to most recent measurements and rates of change, both for the Mauna Luo site itself and a global estimate.

The rate of increase varies from year to year; as short term variations that arise from any changes in the global carbon cycle. Over all there is a significant increasing trend in the rate of increase, and a 10 year moving average (for example) shows the rate increasing from around 1.5 ppm/yr to around 1.9 ppm/yr as described in the report. This is a more than a slight hint of acceleration. It is about 27%, though with limited precision.

The data for emissions is cited to Le Quéré et al. (2009) which is listed as in press, though it has just now come out as advance online publication. SeeThis has been on my to-do list to write about, as it is particularly relevant to another recent thread on carbon cycles.

This paper notes in the abstract that "fossil fuel emissions increased by 29% between 2000 and 2008", and the text notes an increase of 41% since 1990, as given in the report discussed in this thread. The supplementary information of the paper points us to globalcarbonproject for the emissions data; also tabulated here.

1990 was 6.14 Pg emissions; 2008 was 8.67. The uncertainties are around 6%. This is the 41% increase.

There link from emissions to increasing atmospheric levels is surprising complex; but to a first approximation about 40% of emissions remain in the atmosphere.

In any case, the increase in atmospheric CO2 is from about 1.5 ppm/yr to 1.9 ppm/yr: around 27%, but with a substantially larger uncertainty given the natural variations on top of the trend.

This is not a discrepancy; we are measuring two different things, which are strongly related, but should not be expected to simply have the same value.

Cheers -- sylas

PS. Xnn, you'd be interested in Le Quéré et al (2009). It is looking at all those details of sources and sinks in the carbon cycle.
 
Old Nov27-09, 11:36 PM                  #8
mheslep

mheslep is Offline:
Posts: 1,598
Re: Climate Science Update

Originally Posted by sylas View Post

1990 was 6.14 Pg emissions; 2008 was 8.67. The uncertainties are around 6%. This is the 41% increase.

There link from emissions to increasing atmospheric levels is surprising complex; but to a first approximation about 40% of emissions remain in the atmosphere.

In any case, the increase in atmospheric CO2 is from about 1.5 ppm/yr to 1.9 ppm/yr: around 27%, but with a substantially larger uncertainty given the natural variations on top of the trend.

This is not a discrepancy; we are measuring two different things, which are strongly related, but should not be expected to simply have the same value...
I wonder where the balance of the CO2 emissions go - some to the oceans but surely not all?
 
Old Nov28-09, 03:19 AM       Last edited by sylas; Nov28-09 at 07:28 AM.. Reason: grammar            #9
sylas
 
sylas's Avatar

sylas is Offline:
Posts: 1,434
Blog Entries: 5
Recognitions:
PF Contributor PF Contributor
Science Advisor Science Advisor
Re: Climate Science Update

Originally Posted by mheslep View Post
I wonder where the balance of the CO2 emissions go - some to the oceans but surely not all?
Some goes to terrestrial carbon sinks. It all has to go somewhere, and "land/ocean/atmosphere" is a simple classification of the many sinks involved.

Within this broad classification there are all kinds of sinks and many unknowns. The ocean is a number of different regional oceans, which are not uniform, and involves exchanges over all depths, which are not clear. The land sinks are especially hard to figure out. Generally speaking the fraction of carbon that is taken up into the terrestrial sinks is estimated by seeing what is left over after the atmosphere and oceans are considered. There are attempts to further identify where the various terrestrial sinks can be found; but there's no complete accounting and no way to get a direct measurement of all the land sinks. Some wag once described this as the "missing sink", which now makes a good search term to get started finding relevant research.

The "airborne fraction" is the best known; it is around 40% to 45%. That leaves 55% to 60% for other sinks. Page 12 of this report gives a quick summary. The paper by Le Quéré that I have cited is an important contribution and there is a lot more research on this if you want to keep hunting. From Le Quéré (2009):
Combined evidence from atmosphere and ocean observations constrains the mean uptake rates of land and ocean CO2 sinks to 2.6±0.7 and 2.2±0.4 Pg C yr−1 for 1990–2000, respectively11,19–22.
The emissions amount includes both direct industrial emissions (which is what has increased by 41% since 1990) and also emissions from land use change, especially deforestation. Put together As noted previously direct emissions in 2008 were 8.67 Pg. To this we add about 1.2 Pg from land use change (an estimate from Le Quéré 2009) for 2008, giving 9.9 Pg total in 2008.

The atmospheric increase was 1.66 ppm in 2008, which you can simply multiply by 2.13 to get the atmospheric uptake of 3.54 Pg. This varies a lot from year to year, over recent years 1.9 ppm/yr is about the current rate; pretty close to 4 Pg.

Further breaking it all down is an ongoing open question; sorting out how all carbon cycle will continue to work as it keeps being loaded with carbon is also a major open question and significant uncertainty. The "airborne fraction" is about 43%, and most research indicates this is increasing. This is described in the Copenhagen Diagnosis; and more detail is in Le Quéré (2009).
On average, 43% of the total CO2 emissions each year between 1959 and 2008 remained in the atmosphere, but this fraction is subject to very large year-to-year variability (Fig. 2a). This ‘airborne fraction’ increased on average by 0.3±0.2% yr−1 between 1959 and 2008. There is a 90% probability that this increasing trend is significant taking into account the background variability (Methods). The trend and its significance are sensitive to estimates of LUC emissions, which have large uncertainties.


It seems likely that the trend of an increasing airborne fraction will continue.
 
Old Nov28-09, 12:05 PM       Last edited by Xnn; Nov28-09 at 06:17 PM.. Reason: grammer            #10
Xnn

Xnn is Offline:
Posts: 485
Blog Entries: 2
Re: Climate Science Update

Sylas;

Thanks for the link to the Le Quéré paper. I see that she notes the problems
of quantifying sinks and also explains how economic data is used to measure
emissions along with a host of other estimates. So, there is considerable
uncertainty with all of this.

Her charts show both land and ocean sinks trending more negative,
although in 2008 there was a small up tick in ocean sinks due to La Niña
and the southern annular mode:
During La Niña conditions, the land CO2 sink is enhanced owing to lower
temperatures and wetter conditions in the tropics, whereas the ocean
CO2 sink is reduced owing to more intense equatorial upwelling of carbon-rich
waters. Observations in the equatorial Pacific Ocean corroborate the lower ocean
CO2 sink in 2008 (ref. 23) estimated by the models. The ocean models also
attributed the low ocean CO2 sink in 2008 in part to a weaker Southern Ocean
sink, in response to the continuing increase in the southern annular mode.
Anyhow, it's curious that the sinks are trending towards more negative values
and I wonder if maybe perhaps the GDP method of estimating emissions is biased
as the residual chart (figure 2 e) appears to generally be accumulating.
 
Old Nov28-09, 12:12 PM       Last edited by Naty1; Nov28-09 at 12:25 PM..            #11
Naty1

Naty1 is Offline:
Posts: 1,550
Re: Climate Science Update

Sylas posted:
The wider questions seem to be things like... is global warming real? is it caused by human activities?
The answers to those two questions are actually very straightforward. It's yes, and yes.
Nice try; but such speculation is political in nature not scientific...38,000 scientists (who signed correspondence to the UN) and others who wrote the US congress strongly disagree about man made causes of climate change.

Even in Australia, home of the uopdated report referenced by Silas, government there remains in turmoil over man made global warming and carbon reduction plans. The Australian senate appears likely to reject such legislation for plans passed by their house.

The legitimate answers to those two questions is ACTUALLY dependent on valid data, valid scientific theory, and models that work...NOT what East Anglica "scientists" concocked/invented/created fraudulently for the IPCC.

The earth IS likely warming, just like it has thousands of times in the past...but the earth has emerged from numerous ice ages, some when the earth was virtually covered in mile thick ice...and it will most likely cool as well in the future, also repeating past changes long before man was here.

One recent recent study shows that infrared radiation from a cabon thick(er) atmosphere actually increases, not decreases, as climate models would have you believe. So there is much left to learn before we declare "victory" in our understanding of climate...besides, whose to say that a warmer climate would not be a big net plus??? The Vikings, who tried to settle Greenland when it was previously warm enough to be productive for farming, would likely have argued HOORAY for some warming....
 
Old Nov28-09, 02:34 PM       Last edited by sylas; Nov28-09 at 05:27 PM.. Reason: fix a link            #12
sylas
 
sylas's Avatar

sylas is Offline:
Posts: 1,434
Blog Entries: 5
Recognitions:
PF Contributor PF Contributor
Science Advisor Science Advisor
Re: Climate Science Update

Originally Posted by Xnn View Post
Thanks for the link to the Le Quéré paper. I see that he notes the problems...
That's "she", for what it is worth. Corinne Le Quéré is Professor of Environmental Sciences at the University of East Anglia. Her home page has some good further links.

Anyhow, it's curious that the sinks are trending towards more negative values
and I wonder if maybe perhaps the GDP method of estimating emissions is biased
as the residual chart (figure 2 e) appears to generally be accumulating.
Yes, it is interesting; the residuals are large, which is a good indication of how much still is unknown about the carbon cycle.

I don't think GDP is used to estimate emissions. The connection between GDP and emissions is an observation given the data on each one, and the paper speaks of a need to decouple this observed relationship. Emissions are estimated from energy statistics, according to the associated Global carbon budget 2008 webste, same link as I gave previously for the tabulation of data used in this paper.

All the charts in figure 2 have error bars indicated. The largest uncertainties are associated with carbon sinks on the land; both the indirect emissions (figure 2a) from land use changes and the highly uncertain terrestrial sinks (figure 2c).

The residual is basically a count of how much carbon is missing after they add up the emissions and the estimates for sinks. The comment in the paper itself is:
Our estimates of sources and sinks of CO2 were based on largely independent data and methods. Thus, when all the sources and sinks were summed every year they did not necessarily add to zero, because of the errors in the various methods. The sum of all CO2 sources and sinks, which we call the ‘residual’, spanned a range of ±2.1 Pg C yr−1 (Fig. 2e). This residual was not explained by the atmospheric CO2 growth rate, the CO2 emissions from fossil fuel combustion or the ocean uptake, because the uncertainties in these components were much smaller than the variability of the residual. Errors in LUC flux may explain a small part of the residual, for instance during the late 1990s, when fires in Indonesia were partly caused by land clearance taking advantage of the drought conditions17. Our fire-based LUC anomalies for 1997 were 0.7 Pg C greater than normal and account for one-half of the residual for that year. Overall, the residual was most probably caused by the regional responses of terrestrial vegetation to climate variability, indicating that land models overestimated the response of vegetation to the relatively cool/wet La Niña-like climatic conditions of the mid 1970s and underestimated the response to the volcanic eruption of Mount Pinatubo, in the Philippines, in the early 1990s. This later underestimation has been explained elsewhere as resulting from a missing response in the models to the aerosol-induced increase in the diffuse-light component of surface irradiance, and the subsequent enhancement of light penetration into vegetation canopies29.
From the tabulations, you can use a spread sheet to verify that in fact, the residuals are on average slightly positive with a small trend to being more positive; but of course they are all over the place in general. (Mean 0.273, sd 0.957) (Caution: the tabulation uses slightly different sign conventions to the diagram.) If the paper is correct in supposing that the greatest part of this is due to inaccuracies in estimating how vegetation is taking up CO2, it would mean that some years over estimate and other years underestimate the amount of carbon taken into this sink.

A positive residual means either over estimated emission or (much more likely) underestimated sinks. Hence: "missing sink".

Cheers -- sylas
 
Old Nov28-09, 03:22 PM                  #13
Mark44

Mark44 is Online:
Posts: 4,599
Recognitions:
PF Contributor PF Contributor
Homework Helper Homework Helper
Re: Climate Science Update

Originally Posted by sylas
Corinne Le Quéré is Professor of Environmental Sciences at the University of East Anglia.
The home of the Hadley CRU, which has come under a serious cloud in the last week or two.
 
Old Nov28-09, 03:23 PM                  #14
Mark44

Mark44 is Online:
Posts: 4,599
Recognitions:
PF Contributor PF Contributor
Homework Helper Homework Helper
Re: A better link

Originally Posted by sylas View Post
The Copenhagen Disagnosis
Freudian slip?
 
Old Nov28-09, 04:21 PM       Last edited by sylas; Nov28-09 at 05:26 PM.. Reason: noted affiliations of the 31 authors to the paper            #15
sylas
 
sylas's Avatar

sylas is Offline:
Posts: 1,434
Blog Entries: 5
Recognitions:
PF Contributor PF Contributor
Science Advisor Science Advisor
Re: Climate Science Update

Originally Posted by Mark44 View Post
The home of the Hadley CRU, which has come under a serious cloud in the last week or two.
That's a classic ad hominem; and worse, an indirect smear. It's highly inappropriate.

She's not in the CRU. She's not in any of the emails, except in one case that was an enormous cc to hundreds of scientists all over the world. There's nothing linking her to anything in the whole CRU emails brouhaha. It isn't Hadley CRU, by the way. The Hadley Centre is part of the UK Met Office, a different thing entirely. It's a common confusion. And finally, although there are issues showing up in the hacked emails affair concerning how some CRU personnel responded to the excessive flood of FOI requests they were receiving, there is nothing there whatever to indicate anything wrong with the science.

None of the other co-authors to the paper are in the CRU either. Indeed, Le Quere is the only one of the 31 authors from the Uni of East Anglia. The others come from all over the world, and their contributions and affiliations are in the paper.

If you think there's a science issue, then that might be something for this forum, in a different thread I would suggest. Matters of policy and politics, such as how to deal with FOI or adequate openness with data and so on belong in the Politics and World Affairs forum.

I do understand that people are concerned, and want to have questions answered in relation to the hacked files. I have chosen to be firm to underline that this is actually very serious. Accusations of fraud, or malfeasance, or scientific misconduct, are serious matters. It's not okay just to slip in an insinuations like this in a public forum without some credible basis. Being at the same university doesn't count. Heck; even the emails don't count for much; though that's a different subject for the other forum since it isn't actually about the quality of the science itself. The thread to use at present is this one that is mainly about the hacked files affair.

Also, thanks for picking up my Freudian slip. I've fixed it!

Cheers -- Sylas.

PS. How many Freudian psychologists does it take to change a light bulb?

Answer: Two. One to fit the new bulb, and another to hold my p... THE LADDER. I mean the ladder.
 
Old Nov28-09, 06:37 PM                  #16
Xnn

Xnn is Offline:
Posts: 485
Blog Entries: 2
Re: Climate Science Update

Naty1 & Mark44;

There is clearly a heated political debate concerning what to do about
global warming and that is all well and good. However, the science is
robust enough that attempts to suggest that CO2 emissions are not
at the root of it fall short of being credible.
 
image image
Closed Thread

Tags
climate change, co2, ipcc, warming
Thread Tools


Similar Threads for: Climate Science Update
Thread Thread Starter Forum Replies Last Post
Junior or Senior Faculty Position in Climate Science Greg Bernhardt Science Jobs 0 Aug5-09 06:30 PM
Collection of papers climate science wolram Earth 1 Dec11-08 06:14 AM
Climate Science: Is it currently designed to answer questions? Mk Earth 1 Oct6-08 02:28 PM
Climate science wolram Social Sciences 5 Oct1-08 05:36 PM
Some perspectives on the science of climate change Karl Earth 2 May28-08 02:04 PM

Powered by vBulletin Copyright ©2000 - 2010, Jelsoft Enterprises Ltd. © 2009 Physics Forums
Sciam | physorgPhysorg.com Science News Partner
image
image   image