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Most studies so far have focused on the past 118 years, since record keeping began. This study goes back over 11,000.
[URL="http://www.oregonlive.com/environment/index.ssf/2013/03/oregon_state_university_resear_2.html"]Oregon State University researchers track temperatures back 11,300 years to gauge global warming | OregonLive.com[/URL]
A longer time period is a good idea, but I just can't bring myself to trust ANYONE'S study. There has been a fundamental change in science in the last few decades. Scientists are ready to draw conclusions based on flimsy evidence. This study, for example, uses tree rings to estimate temperatures and draws temperature conclusions from proxies like the magnesium level in sea fossils. I have no idea how reliable those measurement tools are, and they form the bulk of the data. I'm not a botanist but I'm pretty sure there are a lot of factors that can influence tree ring growth besides temperature.
Call me cynical, but I'm not sure there's any pure science anymore; it's all advocacy science, on both sides, especially when it comes to global warming.
[QUOTE=jcb;510452]A longer time period is a good idea, but I just can't bring myself to trust ANYONE'S study. There has been a fundamental change in science in the last few decades. Scientists are ready to draw conclusions based on flimsy evidence. This study, for example, uses tree rings to estimate temperatures and draws temperature conclusions from proxies like the magnesium level in sea fossils. I have no idea how reliable those measurement tools are, and they form the bulk of the data. I'm not a botanist but I'm pretty sure there are a lot of factors that can influence tree ring growth besides temperature.
Call me cynical, but I'm not sure there's any pure science anymore; it's all advocacy science, on both sides, especially when it comes to global warming.[/QUOTE]
You've mis-read the article. This study did NOT use tree rings. The reference to tree rings was a description of previous research that had been done, which did use tree rings, and as a result could only go back 1,500 years. This study used sediment cores, and as a result could go back farther in time. And I'm sorry if you "have no idea how reliable these measurement tools are." Magnesium levels in sea fossils is VERY reliable. Shellfish respond in very predictable ways to changes in temperature.
Not that tree ring data should be dismissed. You're right, "there are a lot of factors that can influence tree ring growth besides temperature." But we do have accurate records of the temperature for about the past 118 years, and it matches up with what is seen in tree rings, so you draw your own conclusions.
"[I]The study tapped 73 sets of climate records, most from ocean sediment cores. Other researchers have inferred temperatures from temperature-sensitive proxies in the cores, such as the levels of magnesium in fossil shells.
Researchers have studied tree-ring data that goes back 1,500 years to estimate temperatures. They've also used individual data sets to try to gauge temperatures over longer periods. But Marcott said previous research hasn't extended global temperatures from proxies beyond the last 2,000 years[/I]."
I'm not going to call you cynical. What I will call you is somebody who read the article with a preconceived conclusion in mind.
Then maybe there weren't folks alive 11000 years ago? Maybe those mastadoons are only 6010 years old. Was there an ice age?I'm more apt to believe that man does make a change to his habitat, some of it that we call beneficial now, maybe a problem later. But nature also does thing to change the planet. Volcanos, asteriods and quakes have changed areas and maybe climate. But one thing is a constant, there will come a time when we over populate.
[QUOTE=RoadToad;510455]You've mis-read the article. This study did NOT use tree rings. The reference to tree rings was a description of previous research that had been done, which did use tree rings, and as a result could only go back 1,500 years. This study used sediment cores, and as a result could go back farther in time. And I'm sorry if you "have no idea how reliable these measurement tools are." Magnesium levels in sea fossils is VERY reliable. Shellfish respond in very predictable ways to changes in temperature.
Not that tree ring data should be dismissed. You're right, "there are a lot of factors that can influence tree ring growth besides temperature." But we do have accurate records of the temperature for about the past 118 years, and it matches up with what is seen in tree rings, so you draw your own conclusions.
"[I]The study tapped 73 sets of climate records, most from ocean sediment cores. Other researchers have inferred temperatures from temperature-sensitive proxies in the cores, such as the levels of magnesium in fossil shells.
Researchers have studied tree-ring data that goes back 1,500 years to estimate temperatures. They've also used individual data sets to try to gauge temperatures over longer periods. But Marcott said previous research hasn't extended global temperatures from proxies beyond the last 2,000 years[/I]."
I'm not going to call you cynical. What I will call you is somebody who read the article with a preconceived conclusion in mind.[/QUOTE]
I may have had a preconceived notion, but it's probably not the one you think. My preconceived notion is that I just don't think ironclad conclusions can be drawn from the type of data we have available. The post-industrial revolution time frame is just too small in the scheme of things.
[QUOTE=jcb;510517]I may have had a preconceived notion, but it's probably not the one you think. My preconceived notion is that I just don't think ironclad conclusions can be drawn from the type of data we have available. The post-industrial revolution time frame is just too small in the scheme of things.[/QUOTE]
Exactly why this study carries more weight. It includes reliable data going back over 11,000 years. But if you had been reading it with an open mind, you would have already figured that out.
I just wonder, in the grand scope of things, if "Mankind" isn't just one more step in the evolution of the planet. Maybe we are just egotistical in our belief that we are the end all species. I wonder if T-Rex said to his wife "We are the top rung on the evolutionary ladder....I mean what could possibly come after us?"