Math

[valkhorn]

Okay, let me rephrase it differently for you.

If the 2010-2019 decade is warmer than the 2000-2009 decade, then I will be "proven wrong" about the magnitude of the natural contribution to Global Warming.

And by the way, there are plenty of natural mechanisms to explain Global Warming over the last 100-150 years that are in the scientific literature.

No.

1) What evidence could turn up TODAY. Forget waiting another 7 years or more for you to change your mind.

2) What are they? (this ought to be good)

It's not volcanic activity.

It's not 'cosmic rays'.

It's not solar radiation.

What is it?

[Snow_Miser]

No.

1) What evidence could turn up TODAY. Forget waiting another 7 years or more for you to change your mind.

2) What are they? (this ought to be good)

It's not volcanic activity.

It's not 'cosmic rays'.

It's not solar radiation.

What is it?

It's not solar activity? There are plenty of papers that suggest an important role for solar activity over the 20th Century.

Want me to provide some links for you?

[skierinvermont]

If 80% of climate models predicted a consistent statistically significant warming during this timeframe while that has been absent, that represents a pretty substantial discrepency between the modeled and the observed temperature trends. I suspect that over the next decade or so, this discrepency will continue to grow. There is no sign of warming resuming anytime soon in the troposphere or the surface, and this is because of multidecadal oceanic oscillations and the sun.

Sounds like you finally understand. Falling outside the 80% ci is noteworthy but not really surprising to me given the record solar minimum and the fact that starting in 1997 is a strongly negative ENSO trend. Starting in 1996 yields a more neutral ENSO trend (still negative) and yields .1 and .12C/decade on Had and GISS respectively.

Also remember that although 1997-present is only .035C/decade on Had, it is .09C/decade on GISS.

[Snow_Miser]

Sounds like you finally understand. Falling outside the 80% ci is noteworthy but not really surprising to me given the record solar minimum and the fact that starting in 1997 is a strongly negative ENSO trend. Starting in 1996 yields a more neutral ENSO trend (still negative) and yields .1 and .12C/decade on Had and GISS respectively.

Also remember that although 1997-present is only .035C/decade on Had, it is .09C/decade on GISS.

Other datasets fluctuate with the trend over the last 15 years or so. RSS/HadSST2 is pretty much an exact flatline over the last 15 years, so there remain some pretty substantial discrepencies with the datasets themselves over the last 15 years.

[valkhorn]

It's not solar activity? There are plenty of papers that suggest an important role for solar activity over the 20th Century.

Want me to provide some links for you?

No need. Here's the data. The data is divergent.

[Snow_Miser]

No need. Here's the data. The data is divergent.

Depends on which TSI dataset you use after 1980. If you use the ACRIM TSI dataset post 1980, there is no such discrepency.

Source: Scafetta and West 2007

Even if the PMOD dataset that was used post 1979 on that chart that you posted turned out to be right, while there would naturally be a discrepency because of the increased anthropogenic forcing in the late-20th Century, a significant role for Solar Activity would still be plausable for the late-20th Century, because the Climate system may not have equilibriated to the high levels of solar activity in the late-20th Century, so constant high solar activity can still cause significant Global Warming in the late-20th Century.

Of course, there still remains a controversy over what Solar Activity actually did over the last 30 years. GCRs have decreased over the late-20th Century, and this is evident in the length of the GCR Flux, the cumulative GCR Flux, and the trend in the GCR Flux in the late-20th Century. The geomagnetic AA Index has also increased in the late-20th Century, which would also indicate an increase in Solar Activity during this timeframe. Both satellites and ground based stations have measured an increase in incoming shortwave radiation reaching Earth's Surface. Numerous papers have documented that, all which would support the ACRIM TSI dataset moreso than the PMOD TSI dataset.

[skierinvermont]

Other datasets fluctuate with the trend over the last 15 years or so. RSS/HadSST2 is pretty much an exact flatline over the last 15 years, so there remain some pretty substantial discrepencies with the datasets themselves over the last 15 years.

I like how 5 years ago the deniers were all using UAH, now they all use RSS.

The 15 year trends (remember strongly negative ENSO trend, record solar min) are:

Had4: .035C/decade

GISS: .085C/decade

RSS: 0

UAH: .09C/decade

The 16 yeard trends (only slightly negative ENSO trend):

Had4: .1C/decade

GISS: .12C/decade

RSS: .03C/decade

UAH: .13C/decade

Satellite average: .08C/decade

Surface average: .1C/decade

You can probably bump all of those by about .01-.02C/decade to get completely ENSO neutral.

[Snow_Miser]

I like how 5 years ago the deniers were all using UAH, now they all use RSS.

The 15 year trends (remember strongly negative ENSO trend, record solar min) are:

Had4: .035C/decade

GISS: .085C/decade

RSS: 0

UAH: .09C/decade

The 16 yeard trends (only slightly negative ENSO trend):

Had4: .1C/decade

GISS: .12C/decade

RSS: .03C/decade

UAH: .13C/decade

Satellite average: .08C/decade

Surface average: .1C/decade

You can probably bump all of those by about .01-.02C/decade to get completely ENSO neutral.

Yes, ENSO and the transition to a -PDO has had a pretty large influence on the climate. The sun's influence will take some more time to manifest itself in the climate records. It's no doubt played a role in the pausing of the warming, but the cooling response from low solar activity has yet to commence, for reasons that the chart I posted of solar activity and temperature in the other thread demonstrated nicely.

[valkhorn]

Depends on which TSI dataset you use after 1980. If you use the ACRIM TSI dataset post 1980, there is no such discrepency.

Source: Scafetta and West 2007

Even if the PMOD dataset that was used post 1979 on that chart that you posted turned out to be right, while there would naturally be a discrepency because of the increased anthropogenic forcing in the late-20th Century, a significant role for Solar Activity would still be plausable for the late-20th Century, because the Climate system may not have equilibriated to the high levels of solar activity in the late-20th Century, so constant high solar activity can still cause significant Global Warming in the late-20th Century.

Of course, there still remains a controversy over what Solar Activity actually did over the last 30 years. GCRs have decreased over the late-20th Century, and this is evident in the length of the GCR Flux, the cumulative GCR Flux, and the trend in the GCR Flux in the late-20th Century. The geomagnetic AA Index has also increased in the late-20th Century, which would also indicate an increase in Solar Activity during this timeframe. Both satellites and ground based stations have measured an increase in incoming shortwave radiation reaching Earth's Surface. Numerous papers have documented that, all which would support the ACRIM TSI dataset moreso than the PMOD TSI dataset.

Your graph still shows divergence in the last part. It's not the sun.

[skierinvermont]

What he posted is not even actual TSI data.. it has gone through a number of modifications that make it unrecognizable.. I don't believe even ACRIM shows that much of an increase. ACRIM shows a very slight increase 1960-2000, PMOD shows a slight decrease.

ACRIM is highly suspect for a number of reasons explained in the following link, not least of which is that it shows the mid-90s solar minimum to have higher TSI than any other minimums and minimums are generally believed to have near identical TSI.

This is another classic example of using a data source despite all the evidence against it.

http://www.skepticalscience.com/acrim-pmod-sun-getting-hotter.htm

[Snow_Miser]

Your graph still shows divergence in the last part. It's not the sun.

Yes, as I said, some sort of divergence probably will occur because of the anthropgenic forcing, but the authors found a solar contribution in the late-20th century to be 40-45%, which would represent a significant solar contribution to the late-20th century warming, the divergence is much less than in the chart you showed. These authors found the solar contribution to be as high as 69% over the last 100 years. This, in conjunction with the PDO and AMO, if correct, would question the IPCC's claim of most of the warming since 1950 being attributable to Greenhouse Gases.

[Snow_Miser]

What he posted is not even actual TSI data.. it has gone through a number of modifications that make it unrecognizable.. I don't believe even ACRIM shows that much of an increase. ACRIM shows a very slight increase 1960-2000, PMOD shows a slight decrease.

ACRIM is highly suspect for a number of reasons explained in the following link, not least of which is that it shows the mid-90s solar minimum to have higher TSI than any other minimums and minimums are generally believed to have near identical TSI.

This is another classic example of using a data source despite all the evidence against it.

http://www.skepticalscience.com/acrim-pmod-sun-getting-hotter.htm

The ACRIM TSI data shows about a 0.5 w/m^2 increase in Solar irradiance in between solar cycles. Accounting for geometry and albedo, this would equate to a forcing around 0.09 w/m^2 during this timeframe from solar irradiance. However, this does not represent the true solar forcing. Accounting for some indirect solar forcings, this value goes up to 0.6-0.7 w/m^2 during the late-20th century, which is no longer an insignificant forcing.

Carbon Dioxide has gone up roughly from 310 ppm to 390 ppm during the late-20th century. If we assume that the radiative forcing for a doubling of CO2 is correct, which is 3.7 w/m^2 per doubling, we can calculate roughly how much of a forcing carbon dioxide has had over this period of time.

Carbon Dioxide has increased roughly 26% over the late-20th century, and this would roughly equate to a forcing of around 0.95 w/m^2. So assuming the ACRIM irradiance trend is correct, the carbon dioxide and solar forcings have been roughly in the same ballpark over the late-20th century.

So if we calculate the percentage of the warming due to natural variation from the sun, we can calculate this to be roughly 42%, which is coincidentally (?) the exact solar contribution that scafetta and west 2007 calculated for the late-20th century warming.

Because ACRIM shows an increase in TSI between minimums means it's wrong? What about GCRs decreasing during that timeframe, or the geomagnetic aa index increasing during this same period? Or the fact that we have dozens of papers measuring and observing an increase in solar radiation reaching the Earth's surface during the late-20th century? You have to ignore a lot of other variables to conclude that PMOD's depiction of a flat TSI slope over the late-20th century is most likely to be correct.

[valkhorn]

The ACRIM TSI data shows about a 0.5 w/m^2 increase in Solar irradiance in between solar cycles. Accounting for geometry and albedo, this would equate to a forcing around 0.09 w/m^2 during this timeframe from solar irradiance. However, this does not represent the true solar forcing. Accounting for some indirect solar forcings, this value goes up to 0.6-0.7 w/m^2 during the late-20th century, which is no longer an insignificant forcing.

Carbon Dioxide has gone up roughly from 310 ppm to 390 ppm during the late-20th century. If we assume that the radiative forcing for a doubling of CO2 is correct, which is 3.7 w/m^2 per doubling, we can calculate roughly how much of a forcing carbon dioxide has had over this period of time.

Carbon Dioxide has increased roughly 26% over the late-20th century, and this would roughly equate to a forcing of around 0.95 w/m^2. So assuming the ACRIM irradiance trend is correct, the carbon dioxide and solar forcings have been roughly in the same ballpark over the late-20th century.

So if we calculate the percentage of the warming due to natural variation from the sun, we can calculate this to be roughly 42%, which is coincidentally (?) the exact solar contribution that scafetta and west 2007 calculated for the late-20th century warming.

Because ACRIM shows an increase in TSI between minimums means it's wrong? What about GCRs decreasing during that timeframe, or the geomagnetic aa index increasing during this same period? Or the fact that we have dozens of papers measuring and observing an increase in solar radiation reaching the Earth's surface during the late-20th century? You have to ignore a lot of other variables to conclude that PMOD's depiction of a flat TSI slope over the late-20th century is most likely to be correct.

Wot.

You say CO2 has increased, therefore forcing would increase - yet you say it has been in the same ballpark?

News flash - an increase in CO2 ceterus parabus will ALWAYS yield a net warming effect. This is fundamental physics. Do you argue this?

Now you go off into the GCR argument - which is an amusing 'last stand' from a denialist.

[Snow_Miser]

Wot.

You say CO2 has increased, therefore forcing would increase - yet you say it has been in the same ballpark?

News flash - an increase in CO2 ceterus parabus will ALWAYS yield a net warming effect. This is fundamental physics. Do you argue this?

Now you go off into the GCR argument - which is an amusing 'last stand' from a denialist.

Because CO2 has increased means that natural factors have not contributed to the warming as well? This argument doesn't make any sense.

I have never denied CO2 contributing to Global Warming.

You on the other hand seem reluctant to even attribute part of the warming to natural variation.

What is a denialst, and what are they denying?

[Mallow]

snowlover may be wrong about the issue of climate change, but he's right about the statistics here.

If a "trend" is statistically indistinguishable from a zero trend, one can rightly say there is no (statistically significant) trend.

Of course, that's not to say that there is no trend. Just that, given the information you have, you cannot discern one, so it's statistically indistinguishable from a zero trend.

So if the measured +0.03C trend is statistically indistinguishable from a zero trend, one cannot say with confidence that there is, in actuality, a positive trend.

[Snow_Miser]

snowlover may be wrong about the issue of climate change, but he's right about the statistics here.

If a "trend" is statistically indistinguishable from a zero trend, one can rightly say there is no (statistically significant) trend.

Of course, that's not to say that there is no trend. Just that, given the information you have, you cannot discern one, so it's statistically indistinguishable from a zero trend.

So if the measured +0.03C trend is statistically indistinguishable from a zero trend, one cannot say with confidence that there is, in actuality, a positive trend.

Thank you.

[skierinvermont]

snowlover may be wrong about the issue of climate change, but he's right about the statistics here.

If a "trend" is statistically indistinguishable from a zero trend, one can rightly say there is no (statistically significant) trend.

Of course, that's not to say that there is no trend. Just that, given the information you have, you cannot discern one, so it's statistically indistinguishable from a zero trend.

So if the measured +0.03C trend is statistically indistinguishable from a zero trend, one cannot say with confidence that there is, in actuality, a positive trend.

The question was not whether the actual trend is positive, the question was whether the observed trend is positive.

[valkhorn]

Because CO2 has increased means that natural factors have not contributed to the warming as well? This argument doesn't make any sense.

I have never denied CO2 contributing to Global Warming.

You on the other hand seem reluctant to even attribute part of the warming to natural variation.

What is a denialst, and what are they denying?

The evidence doesn't show any significant warming due to natural variability. The change is much too rapid for natural factors.

You are denying that man is changing the climate, it seems to me.

[Mallow]

The question was not whether the actual trend is positive, the question was whether the observed trend is positive.

The best you can say about an observed trend that isn't statistically distinguishable from zero is that it's inconclusive. To say a trend is positive when it doesn't fall outside of error/noise bounds is disingenuous, misleading, and not scientifically valid.

That all being said, the trend is also not statistically different from that which would be expected in a warming climate. It falls in that awkward in-between zone. So to say it disproves AGW (or is evidence against it) is also disingenuous, misleading, and not scientifically valid.

[csnavywx]

Real Math:

http://iopscience.iop.org/1748-9326/7/4/044035/pdf/1748-9326_7_4_044035.pdf

Amazing how well Hansen et al. (1981) has stood the test of time and how close the IPCC temp graph has been despite some uncertainty in aerosol forcing.

I would love to get Glory back in orbit so we could do some more precise aerosol measurements and help put the last area of uncertainty to rest. My reasoned guess (based on some studies done and papers published) is that the aerosol effect (direct and especially indirect) has significantly helped to mask the GHG response this past 12 years. Recent data suggest that effect should have leveled off at least somewhat after 2007/2008 due to the widespread deployment of SO2 scrubbers in China (who now burns nearly half the world's coal), which reversed their gangbusters SO2 emissions growth rate (7+% per year or a doubling period of only 10 years). Of course, we still have India to contend with, but, as with China, if the air quality get too bad, they'll clean it up after enough people complain.

A side effect of stable or decreasing aerosol forcing (rather than increasing) under a clean-up scenario is that GHG forcing emerges strongly and it can be rather sudden (like the late 70s/early 80s) as the "mask" is removed.

[skierinvermont]

The best you can say about an observed trend that isn't statistically distinguishable from zero is that it's inconclusive. To say a trend is positive when it doesn't fall outside of error/noise bounds is disingenuous, misleading, and not scientifically valid.

That all being said, the trend is also not statistically different from that which would be expected in a warming climate. It falls in that awkward in-between zone. So to say it disproves AGW (or is evidence against it) is also disingenuous, misleading, and not scientifically valid.

You are reading too much into it. The statement that the observed trend of +.03C/decade is positive is a simple statement of fact. It says nothing about what the actual trend is.

[Mallow]

You are reading too much into it. The statement that the observed trend of +.03C/decade is positive is a simple statement of fact. It says nothing about what the actual trend is.

The fact that 0.03 > 0, mathematically speaking, is not debatable. But the "observed trend" necessarily carries with it some uncertainty, which cannot be ignored.

[skierinvermont]

The fact that 0.03 > 0, mathematically speaking, is not debatable. But the "observed trend" necessarily carries with it some uncertainty, which cannot be ignored.

Indeed, which is why I said there is ~10% probability that the actual trend falls outside the range of 95% of model simulations.

The point is an observed trend of .03 is not the same as an observed trend of 0.

[Snow_Miser]

Indeed, which is why I said there is ~10% probability that the actual trend falls outside the range of 95% of model simulations.

The point is an observed trend of .03 is not the same as an observed trend of 0.

Statistically speaking, they are not distinguishable from each other.

[Snow_Miser]

The evidence doesn't show any significant warming due to natural variability. The change is much too rapid for natural factors.

You are denying that man is changing the climate, it seems to me.

Solar activity has ramped up dramatically in the 20th century, and has been at high levels not seen for 10000 years.

[valkhorn]

Solar activity has ramped up dramatically in the 20th century, and has been at high levels not seen for 10000 years.

Show you work.

[skierinvermont]

Statistically speaking, they are not distinguishable from each other.

You've already conceded the point that the observed trend is within the 95% confidence interval and there is only a ~10% chance that the actual trend falls outside the 95% confidence interval. I don't know what you're arguing about now. Do you think the rest of us are too stupid to understand the concept of error bars and sampling error?

[Snow_Miser]

You've already conceded the point that the observed trend is within the 95% confidence interval and there is only a ~10% chance that the actual trend falls outside the 95% confidence interval. I don't know what you're arguing about now. Do you think the rest of us are too stupid to understand the concept of error bars and sampling error?

What Mallow and I are discussing about with the trend not being statistically different than zero. This is as simple and as basic of a fact as observing the sky to be blue on a sunny day.

If you want to continue to be willfully ignorant, that's your choice.

[Snow_Miser]

Show you work.

This chart is from Steinhilber et al. 2012

[valkhorn]

This chart is from Steinhilber et al. 2012

Thank you, however to look at man's effect on climate you can't look at a time scale of 10,000 years. You must look at a scale of 100 or 150. According to your chart, solar radiation has been fairly stable, has it not? And the peak you see - if you look at a shorter time scale, does not correlate to the current warming that we are seeing.

Yes, climate scientists are fully aware of the sun and its variability and incorporate it into their forecast models. If the sun was behind most of the warming that we're seeing now, then how come there is such a consensus (and peer-reviewed research) that shows it is NOT behind the current warming, but increased CO2 is behind it. In fact, the models are not accurate UNTIL you incorporate increased CO2 due to man's activity.

I'm not sure if you agree that anthropogenic global warming is happening, or that it isn't. Your conclusions haven't been clear.