Guest post By Girma Orssengo, MASc, PhD
Comparison of the claims by the Intergovernmental Panel on Climate Change (IPCC) of 1) “Most of the observed increase in global average temperatures since the mid-20th century is very likely” man made, and 2) “For the next two decades a warming rate of 0.2 deg C per decade is projected” are shown in this article not to be supported by the observed data, thus disproving IPCC’s theory of man made global warming.
FIRST IPCC CLAIM
In its Fourth Assessment Report of 2007, IPCC’s claim regarding global warming was the following [1]:
Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.
Let us verify this claim using the observed data from the Climate Research Unit (CRU) of the University of East Anglia [2]. In this claim, “mid-20th century” means year 1950. As a result, according to the IPCC, global warming since 1950 is mostly man made.
To verify the claim that global warming since 1950 is mostly man made, we may compare the global warming rate in degree centigrade (deg C) per decade in one period before 1950 to that of a second period after 1950 to determine the effect of the increased human emission of CO2. To be able to do this, we need to identify these two periods, which may be established from the Global Mean Temperature Anomaly (GMTA) data of the CRU shown in Figure 1.
In Figure 1, the GMTA could be visualized as the sum of a Linear GMTA that has an overall warming rate of 0.6 deg C per century and an Oscillating GMTA that oscillates relative to this overall linear warming trend line. This Oscillating GMTA indicates the relative warming and cooling phases of the globe.
As our objective is to verify the claim that global warming since 1950 is man made, we need to identify two global warming phases before and after 1950. To clearly see the global warming and cooling phases, we plot just the Oscillating GMTA, which is the GMTA relative to the overall linear warming trend line shown in Figure 1. This can be done by using an online software at www.woodfortrees.org by rotating the overall linear warming trend line to become horizontal by using a detrend value of 0.775 so that the Oscillating GMTA has neither overall warming nor cooling trend. The noise from the Oscillating GMTA is then removed by taking five-years averages (compress = 60 months) of the GMTA. The result thus obtained is shown in Figure 2.
”]
Figure 2 shows the following periods for relative global cooling and warming phases:
- 30-years of global cooling from 1880 to 1910
- 30-years of global warming from 1910 to 1940
- 30-years of global cooling from 1940 to 1970
- 30-years of global warming from 1970 to 2000
If this pattern that was valid for 120 years is assumed to be valid for the next 20 years, it is reasonable to predict:
- 30-years of global cooling from 2000 to 2030
Figure 2 provides the two global warming phases before and after 1950 that we seek to compare. The period before 1950 is the 30-years global warming period from 1910 to 1940, and the period after 1950 is the 30-years global warming period from 1970 to 2000.
Figure 2 also provides the important result that the years 1880, 1910, 1940, 1970, 2000, 2030 etc are GMTA trend turning points, so meaningful GMTA trends can be calculated only between these successive GMTA turning point years, which justifies the calculation of a GMTA trend starting from year 2000 provided latter in this article.
Once the two global warming periods before and after mid-20th century are identified, their rate of global warming can be determined from the GMTA trends for the two periods shown in Figure 3.
”]
According to the data of the CRU shown in Figure 3, for the 30-years period from 1910 to 1940, the GMTA increased by an average of 0.45 deg C (3 decade x 0.15 deg C per decade). After 60 years of human emission of CO2, for the same 30-years period, from 1970 to 2000, the GMTA increased by an average of nearly the same 0.48 deg C (3 decade x 0.16 deg C per decade). That is, the effect of 60 years of human emission of CO2 on change in global mean temperature was nearly nil, which disproves IPCC’s theory of man made global warming.
SECOND IPCC CLAIM
In its Fourth Assessment Report of 2007, IPCC’s projection of global warming was the following [5]:
For the next two decades, a warming of about 0.2 deg C per decade is projected for a range of SRES emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 0.1 deg C per decade would be expected.
Let us verify this projection using the observed data from the CRU [2]. This may be done by comparing the global warming rate between the last two decades as shown in Figure 4. In this figure, the global warming rate decelerated from 0.25 deg C per decade for the period from 1990 to 2000 to only 0.03 deg C per decade for the period since 2000, which is a reduction by a factor of 8.3, which further disproves IPCC’s theory of man made global warming. If the current global warming trend continues, the GMTA will increase by 0.27 deg C (0.03 x 9) by 2100, not the scary 2.4 to 6.4 deg C of the IPCC.
Note that the projection for the current global warming rate by the IPCC was 0.2 deg C per decade, while the observed value is only 0.03 deg C per decade. As a result, IPCC’s Exaggeration Factor is 6.7.
”]
SUMMARY
As shown in Figures 3 and 4, claims by the IPCC of 1) “Most of the observed increase in global average temperatures since the mid-20th century is very likely” man made, and 2) “For the next two decades a warming rate of 0.2 deg C per decade is projected” are not supported by the observed data, thus disproving IPCC’s theory of man made global warming.
According to the CRU data shown in Figure 3, the 30-years global warming from 1970 to 2000, after human emission of CO2 for 60 years, was nearly identical to the 30-years global warming from 1910 to 1940. In the intervening 30-years, there was a slight global cooling from 1940 to 1970. Furthermore, since year 2000, as shown in Figure 4, the global warming rate decelerated by a factor of 8.3 compared to the decade before. This is the story of global mean temperature trends for the last 100 years!
Does not the observed data in Figures 1 and 2 show a cyclic global mean temperature pattern with an overall linear warming rate of 0.6 deg C per century?
Dear citizens of the world, where is the catastrophic man made global warming they are scaring us with?
Or is the scare a humongous version of the “Piltdown man”?
REFERENCES
[1] IPCC: “Most of the observed increase in global average temperatures since the mid-20th century is very likely” man made
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-understanding-and.html
[2] Global Mean Temperature Anomaly from Climate Research Unit of the University of East Anglia (GRAPH)
[2] Global Mean Temperature Anomaly from Climate Research Unit of the University of East Anglia (RAW DATA)
[3] Oscillating Global Mean Temperature Anomaly
[4] Comparison of global warming rates before and after mid-20th century (GRAPH)
[4] Comparison of global warming rates before and after mid-20th century (RAW DATA)
[5] IPCC: “For the next two decades, a warming of about 0.2 deg C per decade is projected”
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/spmsspm-projections-of.html
[6] Deceleration of global warming rate in the last two decades
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Calculation of Global Warming Rates for Each Cooling and Warming Cycle
From Figure 2, GMTA peak years are year 1940 & 2000.
Also, GMTA valley years are 1910 & 1970.
Global warming rate from 1940 to 2000 between the two peaks as end points (one cycle) is about 0.06 deg C per decade:
http://www.woodfortrees.org/plot/hadcrut3vgl/from:1940/to:2000/compress:12/plot/hadcrut3vgl/from:1940/to:2000/trend
Global warming rate from 1910 to 1970 between the two valleys (one cycle) as end points is about 0.06 deg C per decade:
http://www.woodfortrees.org/data/hadcrut3vgl/from:1910/to:1970/compress:12/plot/hadcrut3vgl/from:1910/to:1970/trend
Global warming rate from 1880 to 2000 (two cycles) is about 0.06 deg C per decade:
http://www.woodfortrees.org/data/hadcrut3vgl/from:1880/to:2010/compress:12/plot/hadcrut3vgl/from:1880/to:2010/trend
Conclusion: There has not been any shift in the global warming trend, which further disproves the theory of man made global warming.
A better way to get the underlying trend (and smoothing the supposed cycle instead of emphasisng it), is to run a series of trends with a fixed start point, to see how the trend behaves over longer data periods.
Linear regression runs:
1850 – 1910
1850 – 1940
1850 – 1970
1850 – 2000
1850 – 2010.5
The trend lines get progressively steeper in the positive.
That was done using as much data possible. The same result is achieved using 1880 as a start point, and running trends to each of the nominated phase transition points.
Apart from the statistical benefit of increasing significance with the longer trends, we better map the progress of the underlying centennial trend instead of subjecting the data to a questionable cyclicity.
Girma, the linear trend for the time period in the top post (1880 – 2010) is 0.6. After compression, the detrend value selected is 0.775. Does this ring any alarm bells?
I’ve replicated Orsengo’s graph at woods for trees.
barry
What the GMTA pattern in Figure 2 shows is that it has cooling and warming phases. As a result, your comparing the warming rate of one period that has only one warming phase with another period that has a combination of warming and cooling phases will obviously show the maximum warming rate for the first period.
We must compare two periods that have the same number of cooling and/or warming phases.
For the periods 1940-2000 (one cooling and warming cycle), 1910-1970 (one cycle of warming and cooling) & 1880-2000 (two cycles of cooling and warming) all give you a nearly identical global warming rate of 0.06 deg C per decade as shown in my previous post.
This is also shown in the top post. Missing from the argument is analysis of the contribution of various forcings for those time periods – the study is known as ‘attribution’. I have posted numerous scientific references that DO examine attribution, and the findings are as follows.
Increasing CO2 forces temperature upwards over the century.
For the time period 1910 – 1940, natural forcings provide a positive contribution to the temperature trend. So does CO2. Natural and anthropogenic forcing combine to increase temperatures.
For the time period 1970 – 2000, natural forcings provide a negative contribution to the temperature trend. CO2 provides a positive contribution. The trend is similar to the previous period, but the contribution of natural forcings is negative.
Subtracting the natural forcing from each trend, we find that the forcing from CO2 has increased.
Please refer to my post upthread for references.
The flaw in the your argument is the assumption that natural processes contribute equally to the trends.
Barry
New AGW Theory according to Barry:
For the period from 1970 to 2000, after human emission of CO2 for 60 years, the effects of nature and human emissions of CO2 swapped places to produce the same global warming rate as for the period from 1910 to 1940.
Barry
The global warming rate of about 0.15 deg C for a 30-year period recorded 100 years ago for the period 1910 to 1040 has not been exceeded.
The current global warming rate is only 0.03 deg C per decade.
No alarm.
No catastrophe.
Start to worry if, in the future, the global warming rate in any 30-year period exceeds 0.15 deg C.
STOP SCARING THE WORLD AND BRAIN WASHING KIDS!
There is nothing wrong per se with the statement you’ve typed out.
However, it does not reflect what I have said.
1910 – 1940
CO2 forcings positive (~40% contribution)
Natural forcings positive (~60% contribution)
1970 – 2000
CO2 forcings positive (100% contribution)
Natural forcings negative (0% contribution)
Clear enough?
This is the case if you choose the 30-year warming periods, or divide the century in to pre and post 1950.
You may examine my references upthread for corroboration.
If we consider all causes of temperature change for the 30-year warming periods we find that natural forces are primarily responsible for the early warming, with CO2 providing a significant contribution (ie, natural forcing is dominant, but not solely responsible). For the later period, the warming trend is similar, but the natural contribution is negative or neutral. CO2, then, is the dominant driver of warming in the latter part of the century.
At this stage, I don’t believe humans are able to apportion percentages for the effects of man made and natural forces on the global mean temperature trend.
Barry, we are at 0.03 deg C per decade. Why worry?
Thanks by the way, unlike others in your camp, you play the ball, not the man.
Why worry as what caused the warming as long as the previous recorded maximum rate of 0.15 deg C per decade has not been exceeded?
Actually, we are now at 0.03 deg C per decade.
Please stop the alarm.
Disprove the AGW myth? For me the easiest consideration is at http://cleanenergypundit.blogspot.com
Barry,
Considering this 1970 – 2000 period you claim that doesn’t make any sense at all. Natural ocean cycles and albedo have clearly contributed towards the period.
CO2 forcings positive (100% contribution)
Natural forcings negative (0% contribution)
If all forcings were only CO2 that means there is no influence from CO2 at all this past decade. There has been at best an 0.03c rise over the past decade not including made up data at the poles, using no observations. This is so much wrong with the above conclusion it’s not worth going any further.
It is clear by observed planet data that natural forcing drives climate not CO2.
I see a lot of assertions but no references. Is there anything to back up these opinions?
For instance:
Ok, can you point me in the direction of the material you’ve read that helped you establish this position?
There is, of course, uncertainty, particularly in the early part of the record. But the same goes for temperatures. The error bars on early temps are wider than recent temps. Do you think this qualification should appear in the top post, and modify the quite absolute conclusions? I do.
And;
In what way? What caused ocean and albedo changes? Where are the scientific references that helped you form your opinion on the 1970 – 2000 period?
It’s far too early to discern the climate trend from 2000. We’ll be able to say something meaningful (statistically significant) about climate from 2000 in 10 years. Weather influences dominate any trend from then at this time.
Just for fun, though, seeing as we’re playing with short time periods, the global temperature trend since 2008 is 1.1C/decade. Global warming has returned with a vengeance! 😉
I have no emotional attachment to the issue of global warming. I am fascinated by science, how people interpret it, and how people think, particularly amongst the skeptical milieu. I’ve learned that as a general rule, scientists qualify their conclusions (read just about any scientific paper): blog-based skepticism usually expresses itself in absolute terms (like news headlines – on either side). There’s plenty to keep me interested here, and enough convivial conversation to engage. I return the compliments on keeping to the subject, Girma. 🙂
Barry
I wrote:
At this stage, I don’t believe humans are able to apportion percentages for the effects of man made and natural forces on the global mean temperature trend.
You wrote:
Ok, can you point me in the direction of the material you’ve read that helped you establish this position?
I respond:
I point you not to the interpretation by others, but to the data and IPCC’s claims.
IPCC Claimed for 0.2 deg C per decade global warming rate without CO2 restrictions and for 0.1 deg C per decade warming rate with CO2 restriction at the 2000 level. What does the observed data show? Only 0.03 deg C per decade as shown in Figure 4. What is IPCC’s Magnification factor for the first case? =>0.2/0.03=6.7; What is IPCC’s Magnification factor for the second case? =>0.1/0.03=3.3. So IPCC, without the obfuscation of the AGW camp, is dead wrong. Here is its own graph compared to actual observation:
http://wattsupwiththat.files.wordpress.com/2010/04/orssengo1.jpg
What does this result show? All observed temperatures BELOW IPCC’s projections for the case if CO2 had been held constant at the 2000 level.
This is not science; it is “Voodoo Science”
Why does IPCC want to increase fossil fuels prices and destroy the world economy and cause immense pain when human emission of CO2 has nothing to do with global mean temperature?
Where does the IPCC posit that it wants to increase fossil fuel prices? I haven’t seen that in the report. My inclination is to reject this assertion outright, but I’ll wait to see if you can provide a reference from the body of the report. A page number would be good so I can check the context.
IPCC posited a 0.2C rise per decade over the following two decades (from 2007, when the report was published). It is premature to judge three years out, and ten-year cool/flat trends are observed in the centennial trend, which is warming overall. Mid-range model projections ensembles also have runs with decadal flat or cooling trends, that wind up hot over the long-term.
I don’t know how many times it takes to point out that a ten or twelve year trend is not statistically significant with respect to climate, before it sinks in. We will likely get neutral or cool trends for a decade into the future, even if the centennial trend winds up matching projections.
Economic forecasts of mitigation costs put the figures around 1 – 2% of GDP. Forgive me, but I see your comment as the skeptics brand of alarmism.
Personally, I doubt governments, particularly democracies, will do much for the foreseeable future. They are systemically unequipped to deal with long-term issues. Why worry?
I put this poorly
“We will likely get neutral or cool trends for a decade into the future, even if the centennial trend winds up matching projections.”
Should be;
We will likely get neutral or cool trends for a decade here and there as we move towards 2100, even if the centennial trend winds up matching projections.
Girma, you realize that your reply to my query on your sources for attribution – has nothing to do with attribution?
Barry
Thank you.
Barry, I have one question.
Do you agree or disagree that the short-term comparison between IPCC projections and observed GMTA is as shown in the following graph?
http://wattsupwiththat.files.wordpress.com/2010/04/orssengo1.jpg
Do you agree or disagree that the observed GMTA are below IPCC projection even for the case if human emissions of CO2 had been held at the 2000 level?
Yes, Girma. I agree that’s what the graph shows.
Barry
My hat tip to you Barry.
Thank you so much.
Barry
Girma, you realize that your reply to my query on your sources for attribution – has nothing to do with attribution?
As IPCC’s projections as shown in the above link are wrong, its attribution cannot be right.
Your logic is this:
Because someone is wrong about X, they must also be wrong about Y (and Z, A, B, C etc…)
You think that’s sound reasoning?
But the IPCC is not ‘wrong’ here. Rather, the test is invalid for a number of reasons.
The argument based on that graph relies on 4 years of data – the divergence from the projections from 2005 – 2009.
If ten years of data is too short for a meaningful trend, 4 years is even worse.
The IPCC projection lines shown in the graph are averages. They do not show, or attempt to predict interannual weather variability. A number of model runs in the IPCC mid-range ensembles show similar temps and trends to what is being observed – and they end up in the mid-range projections (2-3C) by 2100. That’s just a fluke of course. The IPCC runs do not and cannot predict interannual weather variability. The fact is, the recent variability, including the flat trends and the low 2008 global temperature, is contained within the full ensemble run for the mid-range projections. The graph does not show that variability.
Basically, the graph is comparing apples with oranges – climate vs. weather variability.
If you want to understand the invalidity of using short periods as an argument for climate trends, I will demonstrate using the woodofrtrees web site so that you can check the results and play with the variables yourself.
Barry
Because someone is wrong about X, they must also be wrong about Y
No. It is actually Because someone is wrong about X, they must also be wrong about X; where X is determination of global warming rates.
Don’t you think it is more meaningful to look at a decadal global warming trend as indicator of global warming than talking about the “maximum annual temperature since record began”? (Look at Figure 4)
Since global warming rate is positive and was 0.15 deg C per decade 100 years ago, does not this mean that the temperature in a given decade is in general greater than the decade before? Why is this used as scaring tactic by environmentalists?
I follow this discussion and find that most arguments are within the IPCC NewSpeak vocabulary which leads nowhere. I am slowly becoming convinced that the whole IPCC AGW pronouncement amounts to the biggest political and intellectual fraud ever. Reason:
Consider published estimates of annual global carbon dioxide emissions in Gt C/year (Gigatonnes of carbon per year):
Gt C/year; average; % :
Respiration (humans, animals, phytoplankton) 43.5-52, avge 47.75, = 22.96%
Ocean outgassing (tropics) 90-100, avge 95, = 45.68%
Soil bacteria, decomposition 50-60, avge 55, = 26.45%
Volcanoes, soil degassing 0.5-2, avge 1.25, = 0.60%
Forest cutting, forest fires 0.6-2.6, avge 1.6, = 0.77%
Anthropogenic emissions (2005) 7.2-7.5, avge 7.35, = 3.53%
TOTAL 192-224, avge 207.95, = 100.00%
I find it hard to believe that about 7 Gt C/year out of total global emissions amounting to some 200 Gt C/year should alone and exclusively be responsible for affecting ‘global climate’, no less — let alone the unresolved question whether even the total of annual CO2 emissions does. Is profound scepticism not the only possible rational response in the light of these figures? I take a lesson from the Brothers’ Grimm ‘Die Sonne bringt es an den Tag’, i.e. ‘Truth Will Out’. And only sceptics will ever find it.
Wow. Barry suggests that the natural contribution is negative or neutral for the 1970 – 2000 period. That was when the warming rate was around 0.06 deg C per decade. We are now at 0.03 deg C per decade. Since CO2 levels are still rising, the natural forcing must be much more negative now in Barry’s eyes to cancel out the CO2 forcing.
Either we are in the middle of a large cooling period that is being counteracted by our emissions, or Barry is wrong. Just in case he is not wrong, we should continue our emissions to keep us from freezing!
John M Reynolds
Barry,
Only 2 climate parameters have changed just before and over the past decade, natural or unatural that we know about, to cause a non-warming period.
These are slightly weaker solar output and cloud levels changing albedo at the surface. Lowering and increasing mid and/or low levels clouds effect how much short-wave radiation warms the oceans. (5 percent change in global cloud levels will make a big difference)
Global cloud and solar levels can be found on the NASA website and at other sources.
Oceans cycles have about 25-30 year periods of warming and cooling demonstrated to be natural with no evidence so far of human contribution. These familar terms are known as the PDO, AMO and have found to occur on the Earth for hundreds of years. The ocean temperatures also have some influence on how the AO and NAO behave. There are many sources and papers about these, but Iv’e linked a simple one from Joe with it’s effects on the Arctic.
http://www.intellicast.com/Community/Content.aspx?ref=rss&a=128
So far the planet Earth is still behaving as theses cycles have expected to behave and hence, why some scientists are forcasting a 20-30 cooler period ahead. (which makes sense)
Refering to the last decade as you do is poor excuse (heard it many times) and shows that you are unable to explain this so why is your view credible? A good climate scientist can explain with scientific evidence virtually all the global temperature changes at whatever time frames. With regards to the sudden warming in just one year was down to a developing El Nino.
p.s. If we take the El Ninos into account of the past decade with numbers higher than La Ninas, this stable trend becomes a cooling one.