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Recent Trends in Global Warming

Thaumaturgy
Posts: 166
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6/4/2012 2:35:57 AM
Posted: 4 years ago
This thread is largely aimed at cbrhawk's contention that the last decade has shown little warming in opposition to the idea that anthropogenic activity is largely responsible for recent warming. The idea being, if I may paraphrase, that since humans are still pumping out tons of greenhouse gases we should still see the temperature rising, but instead we are seeing relatively flat temperature trends over the past decade or so.

I would like to address this piont.

First off: no one in the "agw" camp has ever denied that "natural forcings" can and do have an impact on the global climate. This has never been denied. And it is explicitly discussed by the IPCC and all of the literature published so far. In fact looking at the temperature trends for the past 150 years we see a lot of "variability", much of which is imposed not only by human factors (for instance the "mid century cooling" thought to be largely due to human pollution in the form of sulfate aerosols) but also by natural forcings such as solar effects etc.

Now in order to determine if there is still a "human induced warming" within the variability it is necessary to "filter" out the various other forcings in the data. Remember the trend is, as any kind of complex fit to a line, a "model" based on multiple factors: Y=aX+bY+cZ... and even higher orders of those factors. If you want to find out what the effect of "X" is you must know what the coefficient "a" is as compared to other coefficients and you must be able to filter out those other effects to see if "X" is still playing a role.

To that end an article by Foster and Rahmstorff came out in 2011 in "Environmental Research Letters" v6 ( a pdf of which can be freely downloaded from here: http://iopscience.iop.org... )

This is an analysis of temperature trends from 1979 to 2010. They use a variety of detailed methods to "filter" out such natural factors as solar activity, ENSO and volcanic activity and apply these to data sets from NASA/GISS, NOAA, HadCRU, RSS and UAH). They even work out the "lag times" from these effects and find that there is a consistent global warming trend over this time frame.

Figure 5 in the paper is quite stunning when one removes the natural forcing variability terms. And it is seen in all 5 temperature data sets.

These filtered effects result in "short term temperature variability" and chief among these appears to be ENSO, with volcanic activity #2 and solar #3.

They conclude:

"The resultant adjusted data show clearly, both visually and when subjected to statistical analysis, that the rate of global warming due to other factors (most likely these are exclusively anthropogenic) has been remarkably steady during the 32 years from 1979 through 2010. There is no indication of any slowdown or acceleration of global warming, beyond the variability induced by these known natural factors." (emphasis added)
16kadams
Posts: 10,497
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6/4/2012 8:28:42 AM
Posted: 4 years ago
From what I have seen using satelites the warming was either flat, decreasing, or increasing slower then it was before.

Idk, I believe it's happening but not the AGW hypothesis
https://www.youtube.com...
https://rekonomics.wordpress.com...
"A trend is a trend, but the question is, will it bend? Will it alter its course through some unforeseen force and come to a premature end?" -- Alec Cairncross
Thaumaturgy
Posts: 166
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6/4/2012 8:41:05 AM
Posted: 4 years ago
At 6/4/2012 8:28:42 AM, 16kadams wrote:
From what I have seen using satelites the warming was either flat, decreasing, or increasing slower then it was before.

Idk, I believe it's happening but not the AGW hypothesis

I suggest taking a look at the article linked there. Especially the figure I noted in my post.
RoyLatham
Posts: 4,488
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6/6/2012 10:58:57 AM
Posted: 4 years ago
It's true that global warming crisis advocates always acknowledged the existence of natural forcings. However, the key claim was that in the period of sharp warming from roughly 1980 to 2000 that every source of natural forcing had been accounted for, so that all the warming observed was due to CO2. The hockey stick pushed the claim back a thousand years; yes there are natural forcings, but no the are not operating in recent times. Therefore, CO2 is dominating climate. With the hockey stick showing a rapid rise, and confidence that no other climate factors were currently important, then 2000-2010 would surely see continued dramatic rise.

All the talk was of having reached a tipping point in climate that demanded immediate government action to save the world from frying in short order.

The lack of warming in 2000-2010 killed the claim that nothing else but CO2 was currently driving climate. One of the overlooked factors was the Pacific Decadal Oscillation (PDO), which has caused Arctic Ice to diminish in roughly 60-70 year cycles. A National Geographic article on the Arctic noted as matter-of-fact the loss of Arctic Ice in the 1880's and late 1930's, without any reference to climate change. I have not heard of an explanation for the PDO; is it just resonance, or is related to solar activity?

We know that the effect of the PDO is so great to overcome whatever effects CO2 is having. The CO2 crisis advocates are now regrouping under the theme that maybe they didn't have climate completely solved in 2000, but now they have it completely solved.

The revised models, however, do not track past climate as reconstructed by paleoclimatologists. That problem is resolved by crisis advocates by saying the differences are accounted for in the climate reconstructions, not in the models. This mirrors the unsuccessful efforts to do away with the Medieval Warm Period and the Little Ice Age in climate history.

Every time the models are revised, the effects of CO2 are reduced. Skeptics agree that CO2 is causing some global warming, and they have always said that. The question is how much. I think it's fair to say that scientific progress is being made. Every time the models are adjusted to reflect undeniable reality, we get closer to solving the problem. Maybe another decade or two of research will produce a good understanding.
Thaumaturgy
Posts: 166
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6/7/2012 10:56:46 AM
Posted: 4 years ago
At 6/6/2012 10:58:57 AM, RoyLatham wrote:
The lack of warming in 2000-2010 killed the claim that nothing else but CO2 was currently driving climate.

Again, I believe the point of the article was and continues to be (despite no one actually seeming to pay attention to it in this particular thread) that there are short-term variability factors that are natural. The authors of the article I cited explicitly talk about the influence of short-term factors such as ENSO and solar.

So you guys are, by definition, focusing exclusively on a "short term" (2000-2010 in your words, Roy) and guess what? Short terms in time series suffer from this!

The key is what is the overall trend doing?

The idea that human-produced CO2 is driving a lot of the current warming is what is being tested for here, but the only way to do that is parse out from the multiple regression those things which are not related to anthropogenic CO2 and see how much variance they add to the data.

cbrhawk and others have pointed out that if CO2 is the main driver and humans have produced a lot of CO2 recently why is the temperature range flat? Well that's what is meant by "short term variability" from natural forcings. The natural forcings are NOT absent, but the CO2 forcing is still there under the noise (the variability) of the natural systems.

Imagine if you told your kids that going to a steady diet of "Who" concerts would damage their hearing so they go anyway. But while at a recent one someone stuffs some cotton in your kids ears for a show, maybe two, it will "moderate" the trend of decaying hearing loss, but not really change it, especially if they keep going to concerts and do so without hearing protection. That doesn't mean that Pete Townsend has "turned down his amp", just that there was a short term counterfactor in there.

(I use this example for those of us that are older since I'm not even sure Pete plays live a lot these days and due to his own hearing loss I don't know how loud he plays, etc. But you get the point).

One of the overlooked factors was the Pacific Decadal Oscillation (PDO), which has caused Arctic Ice to diminish in roughly 60-70 year cycles.

Again, like transitional fossils there's always more to be found and tested. My understanding of the PDO is that it has a 10-40 year cycle and further the PDO does not seem to show an overall long-term trend (http://jisao.washington.edu...) so it is hard to imagine it as driver for the long term warming we see overall. It is merely a way of moving heat around in the ocean.

Again, it appears that it can act as a source of short term variability in the data.

A National Geographic article on the Arctic noted as matter-of-fact the loss of Arctic Ice in the 1880's and late 1930's, without any reference to climate change. I have not heard of an explanation for the PDO; is it just resonance, or is related to solar activity?

The PDO is still under investigation (I know that's a good start for more "skeptic" doubt mongering! Just like any question in geology allows creationists to throw out all of geology, any question in earth science here can allow for pure unadulterated conjecture and hope that everything is wholly unknown).
16kadams
Posts: 10,497
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6/7/2012 11:51:48 AM
Posted: 4 years ago
At 6/4/2012 8:41:05 AM, Thaumaturgy wrote:
At 6/4/2012 8:28:42 AM, 16kadams wrote:
From what I have seen using satelites the warming was either flat, decreasing, or increasing slower then it was before.

Idk, I believe it's happening but not the AGW hypothesis

I suggest taking a look at the article linked there. Especially the figure I noted in my post.

k
https://www.youtube.com...
https://rekonomics.wordpress.com...
"A trend is a trend, but the question is, will it bend? Will it alter its course through some unforeseen force and come to a premature end?" -- Alec Cairncross
16kadams
Posts: 10,497
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6/7/2012 12:00:38 PM
Posted: 4 years ago
Let's make a deal.

I have read most of skeptical sciences posts against skeptics.

I have read a few PDF studies on both sides

2 skeptic books

If warming is occurring as your PDF file claims, and it continues at that same rate for 20 more years (we are supposed to cool soon) I will become an alarmist.
If it stays flatline like satilite data says, or falls, I will remain a skeptic.
https://www.youtube.com...
https://rekonomics.wordpress.com...
"A trend is a trend, but the question is, will it bend? Will it alter its course through some unforeseen force and come to a premature end?" -- Alec Cairncross
Thaumaturgy
Posts: 166
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6/7/2012 1:36:57 PM
Posted: 4 years ago
At 6/7/2012 12:00:38 PM, 16kadams wrote:
Let's make a deal.

I don't care to "make a deal" with anyone on this. You can decide to act however you want and take or leave whatever science you like or not.

If warming is occurring as your PDF file claims, and it continues at that same rate for 20 more years (we are supposed to cool soon) I will become an alarmist.

Do whatever you like. I suspect after a while it won't be a "personal choice" anymore than opting to be a "gravitational alarmist" (which is the personal choice I make which keeps me from jumping off of high places)

If it stays flatline like satilite data says, or falls, I will remain a skeptic.

Is it proving difficult to find "FIGURE 5" in the paper? Just curious. Because no one seems to be talking about what the paper shows.

Figure 5 is the one with the phrase "Figure 5" under it. It's on page 5 of the pdf.
16kadams
Posts: 10,497
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6/7/2012 1:39:26 PM
Posted: 4 years ago
At 6/7/2012 1:36:57 PM, Thaumaturgy wrote:
At 6/7/2012 12:00:38 PM, 16kadams wrote:
Let's make a deal.

I don't care to "make a deal" with anyone on this. You can decide to act however you want and take or leave whatever science you like or not.

If warming is occurring as your PDF file claims, and it continues at that same rate for 20 more years (we are supposed to cool soon) I will become an alarmist.

Do whatever you like. I suspect after a while it won't be a "personal choice" anymore than opting to be a "gravitational alarmist" (which is the personal choice I make which keeps me from jumping off of high places)

If it stays flatline like satilite data says, or falls, I will remain a skeptic.

Is it proving difficult to find "FIGURE 5" in the paper? Just curious. Because no one seems to be talking about what the paper shows.

Figure 5 is the one with the phrase "Figure 5" under it. It's on page 5 of the pdf.

I saw it
I also saw NOAA data
https://www.youtube.com...
https://rekonomics.wordpress.com...
"A trend is a trend, but the question is, will it bend? Will it alter its course through some unforeseen force and come to a premature end?" -- Alec Cairncross
16kadams
Posts: 10,497
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6/7/2012 1:40:48 PM
Posted: 4 years ago
At 6/7/2012 1:39:26 PM, 16kadams wrote:
At 6/7/2012 1:36:57 PM, Thaumaturgy wrote:
At 6/7/2012 12:00:38 PM, 16kadams wrote:
Let's make a deal.

I don't care to "make a deal" with anyone on this. You can decide to act however you want and take or leave whatever science you like or not.

If warming is occurring as your PDF file claims, and it continues at that same rate for 20 more years (we are supposed to cool soon) I will become an alarmist.

Do whatever you like. I suspect after a while it won't be a "personal choice" anymore than opting to be a "gravitational alarmist" (which is the personal choice I make which keeps me from jumping off of high places)

If it stays flatline like satilite data says, or falls, I will remain a skeptic.

Is it proving difficult to find "FIGURE 5" in the paper? Just curious. Because no one seems to be talking about what the paper shows.

Figure 5 is the one with the phrase "Figure 5" under it. It's on page 5 of the pdf.

I saw it
I also saw NOAA data

Figure 5 some of them (HTML) show cooling
https://www.youtube.com...
https://rekonomics.wordpress.com...
"A trend is a trend, but the question is, will it bend? Will it alter its course through some unforeseen force and come to a premature end?" -- Alec Cairncross
Thaumaturgy
Posts: 166
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6/7/2012 2:06:25 PM
Posted: 4 years ago
At 6/7/2012 1:40:48 PM, 16kadams wrote:
Figure 5 some of them (HTML) show cooling

Wow, how far down did you have cherry-pick window the data down to see "cooling"?