Monday, May 18, 2009

Global Warming Tiger - Natural Cycles

This is the third of the series Global Warming - Tale of the Tiger.

Read the first posting in this series: Tale and a description of the figure to the left. I believe the apparent 0.8ºC increase in Global Temperature over the past 150 years is due to three major causes and one minor one, as indicated by the parts of the "tiger". (The second posting details Data Bias.)

This posting is about NATURAL CYCLES that I estimate are responsible for about 40% of the apparent warming. In other words, 0.3ºC to 0.4ºC of the apparent 0.8ºC temperature increase is due to natural cycles not under human control.

You are familiar with three of the natural cycles that affect the energy input and heat balance of the Earth: 1) diurnal - the daily rotation of the Earth, 2) seasons - Earth's yearly orbit around the Sun, and 3) sunspots - 9 to 13-year magnetic cycles on the Sun. Sunrise to afternoon temperatures vary by 10ºC or more and seasonal temperatures by 40ºC or more.

However, these cycles have no long-term effect on surface temperatures. They are not the cause of Global Warming. However, when scientists are trying to detect long-term temperature variations of fractions of a degree, multi-degree daily and yearly variations complicate the task.

Individual sunspot cycles are not long enough to have significant effects on global temperatures. However, when a multi-decadal series of especially short-strong cycles, or long-weak cycles occur, there are significant effects, see (7) below.

Three more natural variations are called Milankovitch cycles: 3) eccentricity of Earth orbit around the Sun, 4) axial tilt, and 5) precession. These changes do not increase or decrease the total amount of solar radiation falling on the Earth. However, they change the relative distribution between the polar and equatorial regions. It turns out that the more energy that falls on the polar regions, the more the Earth warms, and vice-versa. These cycles run from 19,000 to 400,000 years and they are the most likely cause of the approximate 100,000 year glaciation cycles seen in the ice core records. Over the past 20 thousand years or so, according to ice core data, the Earth has warmed by over 10ºC. During most of that time, human activity had no effect on global temperatures. The Milankovitch cycles may have contributed 0.1ºC or more to the 0.8ºC apparent Global Warming over the past 150 years.

Another set of cycles of interest are: 6) multi-decadal oscillations of the oceans, including the Pacific Decadal Oscillation (20-30 years), Interdecadal Pacific Oscillation (15-20 years) PDO and IDO, El Nino-Southern Oscillation (3-8 years) ENSO, Atlantic Multidecadal Oscillation (70 years) AMO, and others. These cycles are associated with temperature variations of 1ºC or more, and they may have contributed 0.1ºC or more to the 0.8ºC apparent Global Warming over the past 150 years.

The last cycle of interest is: 7) multi-decadal magnetic activity variations on the Sun. As I noted above, individual sunspot cycles, per se, are not associated with significant global temperature variations. However, a series of especially short and strong cycles may be associated with multi-decadal warming trends. Conversely, a series of especially long and weak cycles may be associated with multi-decadal cooling trends. See Solar variation for an excellent discusion.


The figure (from Solar variation, with annotations in green and pink by Ira) compares global temperature with CO2 and Sunspot Number. [Click the diagram for a larger version.]

The upper dark red curve shows how temperatures have increased by an apparent 0.8ºC over the past 150 years. Note that there was a dip around 1860, another around 1910, and a third around 1950. A small, relatively short rise followed the 1860 dip, a larger, longer rise followed the 1910 dip, and the 1950 dip was followed by a very long and strong rise. That last rise has triggered current Global Warming fears.

The middle blue curve shows how CO2 has increased steadily since 1850, with a particularly rapid rise from 1960 to the present. (The reason the blue curve gets brush-like after 1960 is better measurement equipment that captured seasonal variations.) The correlation between CO2 rise and temperature rise has lent credence to the theory that rising CO2 levels are the main cause of Global Warming.

The lower yellow curve shows sunspot number variations. The thin line shows the individual 9 to 13-year sunspot cycles and the thicker line is the multi-cycle average.

My annotation shows, in green, the sunsport cycles that peaked below 80 sunspots/day. Note the correlation between those low cycles and the dips in global temperature experienced about a decade later. Annotations in pink indicate the sunspot cycles that peaked above 110 sunspots/day. Note that the peaks are correlated with those more active sunspot cycles.

In particular, note that six of the last seven sunspot cycles have peaked above 110 and that correllates with the global temperature rise from 1950 to 2000. However, since 1999 there has been a stabilization of global temperatures and, since 2005, a dip of nearly 0.2ºC in the non-smoothed data. That dip is NOT correlated with any dip in CO2 level rise - indeed CO2 levels are rising faster than ever.

Therefore, it is plausable that CO2 levels, while significant, are NOT the primary cause of Global Warming.

So, what is the main cause? Well, look at the thick yellow smoothed sunspot curve. It has been on the downswing for the past decade! The latest averages are below 80!

Couple that with the two-year (and counting) delay in the expected start of sunspot cycle #24. In 2006, NASA experts predicted cycle #24 would start at the end of 2006 or early 2007 and that it would be a doozy, peaking over 150! But, here at mid-2009 #23 has probably not ended yet nor has #24 started. So, NASA's latest prediction is that #24 will be be a weak kitten, peaking at 90. (I predicted, back in January that it would peak even lower, at 80. Also see an "Inconvenient" Minimum.)


Sunspot activity is better correlated with global temperature than CO2 levels. It is probably responsible for about 40% of the apparent Global Warming we have experienced over the past 150 years and over 0.3ºC of the actual warming. If the coming sunspot cycle is further delayed and if it is as weak as expected, that could stabilize global temperatures for a decade or more and give us breathing room to control CO2 levels in a conservative way.

Ira Glickstein


joel said...

Ira concludes: that could stabilize global temperatures for a decade or more and give us breathing room to control CO2 levels in a conservative way.

Joel comments: I don't get it. After all the information that you provide concerning how nature controls global temperature, not mankind, why do you conclude that we should waste our precious resources on what is apparently a fruitless pursuit of CO2? I seem to be missing the point. -Joel

Ira Glickstein said...

Thanks, Joel for your perspicacious question.

I'm hoping that Nature will stabilize temperatures and perhaps reduce them a bit in the coming decades - independent of what we humans do or do not do.

If the Natural Cycles I outline in the most recent posting happen to take us into a new ice age or revert to the warming trends of the past decades, nothing we do will make much difference over the long run.

We will simply have to learn to live (and die) with a much colder or hotter Earth as have our hominid ancestors over hundreds of thousands of years.

On the other hand, as a conservative, I do not believe it is "good" to continue to increase atmospheric CO2 and other carbon gasses by burning unprecedented amounts of sequestered carbon. As we learned in our L-Mind vs C-Mind discussions on this Blog, we C-Minds like to balance "Harm, Fairness, Authority, Ingroup, and Purity", and adopt major change only after due consideration. I think drastic changes in levels of carbon gasses falls in the "Purity" bucket and perhaps "Harm" as well.

If Natural Cycles lead to a cooling period, much of the excess CO2 will be re-absorbed by the oceans, and we will be off the hook until the cycles reverse again. If they revert to warming we will have to learn to live with higher levels of carbon gasses.

If, as I estimate, human-produced carbon gasses are responsible for only 10% of Global Warming, even if we cut them competely it would not change much.

That is why you refer to "a fruitless pursuit of CO2". I agree with you!

However, the "train is already out of the station". The US government is already on the road to pass the Cap and Trade scam and the media and activist public want to do something. I favor a Carbon Tax as a way to "do something" that, like chicken soup, "might not help much but it would't hurt".

Ira Glickstein

joel said...

As an excellent study (which I can't reference at the moment) shows, there are two approaches to planetary temperature change. One is to try to spend your resources to prevent the change and the other is to mitigate the impact of the change on mankind. The former is probably impossible. The latter is worth pursing. It involves designing dikes, reservoirs and shifting some populations. These are doable. I'd rather spend my tax money on the doable rather than the impossible, but it requires a healthy economy that is not sabotaged by political efforts to achieve hidden agendas. -Joel

Ira Glickstein said...

You are correct Joel. Historically, humans, like all other animals and plants have learned to live with gradual climate change. They adapt or genetically evolve or die out and are replaced by other species.

The current warming cycle of about 0.5ºC over the past 150 years is no exception - unless a substantial part of it is due to human activities.

I believe most of it is due to natural cycles that have heated the Earth and carbon gasses released from the oceans due to the warming. Some part of it -I say about 10%- is due to human activities.

If the IPCC is correct and over 50% is due to human activities, that could change things. Temperatures and sea levels and carbon gasses could increase more rapidly than would be the case with natural cycles. That would make it much harder for plants and animals (including humans) to adapt. That is the motivation of the Global Warming alarmists.

Fortunately, the latest evidence has convinved me the IPCC is wrong. It may take another decade to reverse the alarmism. The danger is they will cause us to over-react and pass the Cap & Trade scam and radical environmental regulations which will further wreck the world economy.

Ira Glickstein

Ira Glickstein said...

In a comment to another thread, John asked for a condensed version of my Global Warming thoughts.

1) My "Tale of the Tiger" series estimates that the 0.8ºC temperature rise claimed by IPCC to have occurred over the past 150 years is distributed as follows:

30% Not actual warming, but due to data bias.

40% Actual warming, due to Natural Cycles not human activities.

20% Actual warming, due to Ocean Carbon and other "greenhouse gas" side-effects of the Natural Cycle warming, not human activities.

10% Actual warming, due to Human release of Carbon that has been sequestered over the eons (coal, oil, natural gas).

See the following Topics: plan to post details for Ocean Carbon and Human Carbon soon.

2) The major erroneous implication of Al Gore's "An Inconvenient Truth" movie is the idea that rising CO2 causes rising global temperatures and decreasing CO2 causes decreasing global temperatures. He bases this on the ice core data. A close look at that very data shows that the causation is exactly opposite. Temperature rises dramatically some 800 to 1000 years before CO2. Both remain high for several thousand years, Then, temperature falls dramatically and CO2 follows some 1000 or more years later.

See for details.

3) Despite the erroneous implication in Al Gore's movie, and the small percentage of Global Warming due to human activities, I do believe we should take action to reduce release of CO2 and other carbon gasses. As a conservative, I am worried that the continuing rapid rise in CO2 is unprecedented in the history of the Earth. Even though most of the released CO2 is due to warming due to Natural Cycles, about 30-40% of the CO2 rise is due to human activities.

I favor a Carbon Tax that would be collected at the mine, well, and port on fossil fuels. It would raise the cost of gasoline by about $1/gallon and other fossil fuels in porportion to the released carbon. Such a tax would be relatively hard to avoid and easy to collect. 100% of the money collected would be refunded, on a per capita basis, to all US citizens with a valid Social Security number, so it would be revenue-neutral.

Higher prices for fossil carbon-based fuels and products would encourage industries and individuals to conserve energy with minimal government meddling. (The alternative, "Cap and Trade" is a total scam that will do little to limit carbon and much to enrich the politically-connected.)

See for details.

4) The evidence that carbon gasses are not the primary cause of Global Warming is the reduction in warming, and a bit of cooling, over the past ten years, during which CO2 continues to rise rapidly. This shows that the IPCC models are wrong because they predict that rising CO2 will cause rising temperatures.

Why has there been a reduction in warming and a bit of cooling? It is probably due to Natural Cycles, particularly the reduction in solar activity over the past decade.

See for details.

I hope that is condensed enough.

Ira Glickstein