[bizorky]

The graph shows a stretch of stable temperature lasting for 900 years that suddenly arcs upward in the last century, resembling a hockey stick laid on its side.

"It's a pretty profound, easy-to-understand graph," said Roger Pielke, director of the University of Colorado's Center for Science and Technology Policy Research.

This is interesting: I'd like to know who has been collecting atmospheric temperature data for the last 900 years, and at what elevations. So far as I can recall, satellite measurements of atmospheric temperatures only started to be collected in 1979. Before that, the "global" collection of atmospheric temperature was based on weather stations, many of which were in cities (which are "heat islands") starting in the 1920's.

Tyros, launched in 1979, was the first satellite capabale of reading temperatures around the globe. These readings could be adjusted for altitude, unlike all previous methods of measurement. Before this, data collection was largely ground collection (or surface collection), or with weather balloons, and rather sparse due to the distribution of the stations.

In Canada, meterological measurements and data collection in the high arctic only started in the 1930's, and were carried out first by the RCAF.

Satellite temperature readings have been available for 27 years, far too little time to guage long-term trends. While weather may be variable from one day to the next, climate is a long term trend of an enormous number of weather events. So pardon me if I admit fascination when someone suggests that they have 900 years of accurate atmospheric temperature data.

 

[andreapalladio]

This is interesting: I'd like to know who has been collecting atmospheric temperature data for the last 900 years, and at what elevations

Arctic and Antarctic ice cores are a goldmine of historic weather data. Individual years can be read just like the rings of a tree.

 

[bizorky]

^Actually, you can't tell anything accurate about past air temperature from ice cores. The proxy evidence used in the report in question attempts to extrapolate the surface temperature.

 

[afransen TO]

The really critical question, over and above bizorky's doubts, if whether it is worth the risk. Maybe we're wrong about global warming. But if we're not, it can and probably will cause misery on a scale that can hardly be described, not to mention cost the economy unfathomable amounts. The insurance industry is worried, why aren't you?

 

[bizorky]

^Here is what I said earlier:

I have stated here, and in other posts on this topic, that there is nothing wrong with taking careful steps to reducing greenhouse emissions - even in light of not having a full understanding of the complexity of the atmosphere and climate change processes.

I went a step further and suggested that a better course of action from a public policy perspective was to link CO2 emission reductions with other pollutants. If properly crafted, one can do much more with one clear policy and the programs built upon it.

As for your concerns, suppose for a moment that global warming is caused by natural climate change? What would the difference in outcomes be for the concerns of the insurance industry (and everyone else)?

Suppose the predicted temperature changes don't happen, or are not as dire as predicted? No one will know for sure until that future comes to pass, because the extrapolations based upon the data will only be born out by the facts.


Interestingly, here is a quote from the summary of the report in question (the bolding is mine):

"Based on the analyses presented in the original papers by Mann et al. and this newer supporting evidence, the committe finds it plausible that the Northern hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millenium. The substantial uncertainties currently presented in the quantitative assessment of large-scale surface temperature changes prior to A.D. 1600 lower our confidence in this conclusion compared to the high level of confidence we place in the Little Ice Age cooling and 20th century warming. Even less confidence can be placed in the original conclusions by Mann et al. (1999) that "the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millenium" because the uncertainties inherent in temperature reconstructions for individual years and decades are larger than those for longer periods, and because not all of the available proxies record temperature information on such short timescales."

Another quote from the report in question:

"It should also be noted that the scientific consensus regarding human-induced global warming would not be substantively altered if, for example, the global mean surface temperature 1,000 years ago was found to be as warm as it is today."

The conclusions concerning temperature deal with the mean measurement, and do not suggest uniform warming at every point on the surface. Measurement points for extrapolating surface temperature from the past are selected, and do not intend to measure all places on the globe. This is spelled out in the document.

This last quote is fascinating if you think about it. The same consensus would have been reached even if temperatures had been at the same levels due to natural processes a thousand years ago.

 

[afransen TO]

I find it rather unlikely that humans through their GHG emissions have had no effect on global temperature. The concentration of CO2 in the atmosphere has risen substantially, as well as the levels of most other GHGs except stratospheric ozone.

 

[bizorky]

^That is what all these research efforts are trying to find out. As policies are constructed, there has to be a firm understanding of what is going on in the atmosphere. As I have mentioned, there is nothing wrong with taking preventative measures in reducing CO2 emissions, nor is there anything wrong linking those reductions to reducing other known pollutants.

In terms of global temperatures, solar energy, by far, contributes the greatest amount of heat to the planet, both in terms of surface temperature and atmospheric heating. The sun drives the climate and has done so throughout the history of the planet. I know you know this; the only reason why I am saying it is that what researchers are trying to understand is what effect an incredibly small contribution to the greenhouse effect can have on temperature when compared to considerably more abundant sources.

With respect to greenhouse effects, water vapour and water in clouds absorb 90 percent of the trapped infrared radiation. There is not a tremendous amount of knowledge of how this varried in the past. Nor is there firm understanding whether cloud cover traps more, or reflects more heat energy. The research to understand this is underway.

Carbon dioxide, methane and other minor greenhouse gases make up the other ten percent of the greenhouse effect. However, a considerable portion of those gases are produced naturally, and have been produced for billions of years. Over that time there has been considerable climate variability. There are no absolute links between climate variations and greenhouse gas emissions. This issue is mentioned within the report in question.

While our climate looks relatively static, it is dynamic and always has been. There is a complex mix of solar energy and its variations, planetary heating, increases and decreases in water vapor, changes to continental and ocean distributions, alterations in the ways the oceans have trapped and distributed heat and many more processes that have contributed to climate change.

The real problem lies in separating out human contributions from non-human processes, and figuring out what effect this actually has.

 

[JoeyCuppa]

I think Bizorky works for an oil company. Or he's really Dick Cheney, incognito.

 

[bizorky]

^My only interests in oil are with olive oil.

Some of the first large-scale studies and modelling of human impact on climate were carried out by the United States Department of Energy - under the Reagan administration.


It is faulty reasoning to assume political affiliation when questioning assumptions.

 

[andreapalladio]

Ah, Ronald Reagan. The environmentalist who thought trees cause air pollution.

 

[bizorky]

I didn't say that I know for sure that global warming is happening, I said the consensus within the scientific community is that it is happening. Do we know 100% for sure that global warming is real? No. Is the consensus within the scientific community that global warming is real? Yes. And since I am trained in and believe in science, for the time being I believe it until otherwise proven.

If you don't know global warming is happening then how can you agree that humans are causing it? If we don't know 100% for sure that global warming is real then how can we have a consensus that humans are the prime cause? If there is a consensus for accepting an idea for which there is no fully supportable evidence, then does that consensus mean anything?

Where's your evidence that scientists are still debating whether global warming is real or not?

It is in the actual document itself. You might want to read it rather than citing ABC. I didn't know ABC was a peer-reviewed journal.

 

[ganjavih]

ABC is not the citation I used to demonstrate that the consensus is near unanimous... though I have a feeling you knew this. The citation I used was the review article published in Lancet, a prestigious peer-reviewed journal that's very difficult to publish in (I should know, they rejected my ass). If Lancet isn't your cup of tea, here are recent articles from Science and Nature.

Science 3 December 2004:
Vol. 306. no. 5702, p. 1686
DOI: 10.1126/science.1103618

BEYOND THE IVORY TOWER:
The Scientific Consensus on Climate Change
Naomi Oreskes
Policy-makers and the public who are not members of the relevant research community have had to form opinions about the reality of global climate change on the basis of often conflicting descriptions provided by the media regarding the level of scientific certainty attached to studies of climate. In this Essay, Oreskes analyzes the existing scientific literature to show that there is a robust consensus that anthropogenic global climate change is occurring. Thus, despite claims sometimes made by some groups that there is not good evidence that Earth's climate is being affected by human activities, the scientific community is in overwhelming agreement that such evidence is clear and persuasive.


Nature 441, 583-584 (1 June 2006) | doi:10.1038/441583a; Published online 31 May 2006

Climate change: All in the game
Thomas Pfeiffer1 and Martin A. Nowak1

Human activities have already demonstrably changed global climate, and further, much greater changes must be expected throughout this century. The emissions of CO2 and other greenhouse gases will further accelerate global warming... Some future climatic consequences of human-induced CO2 emissions, for example some warming and sea-level rise, cannot be prevented, and human societies will have to adapt to these changes. Other consequences can perhaps be prevented by reducing CO2 emissions. Everyday measures can contribute to climate protection.

 

[bizorky]

This might be a little all over the place for you, but here we go.

So let's see: there is a consensus, or agreement, that humans are creating climatic effects that are not yet well understood (as documented in the report). There is only detailed recent evidence (forty years or so), but the evidence from the past needed for comparison (upon which this conclusion is based) is fraught with "substantial uncertainties" (words taken from the actual report). So what is actually being compared in order to generate this consensus?

There are scientists who have suggested that recent trends in relating CO2 emissions and guaging tempertature have come from the fact that accurate measuring systems have only come into use over the last 40 years (with meteorological data only going back about 150 years). Some have suggested that this could actually account for the so-called "hockey stick" graph so prominent in the IPCC report in 2001 and 2006, and the subsequent news stories on its significance. The interesting thing is that in the summary section of the actual report, there is an attempt to put this graph into perspective by emphasizing that recent accurate measurements may be skewing its prominence when compared to all the troubling "uncertainties."

It is interesting to note that some of the "uncertain" data within the IPCC report suggests warmer periods in the past, almost as warm as today. If there was no significant population of human beings emitting large quantities of CO2 during those periods, what was causing the variations in temperature? If the data is "uncertain" then how can comparisons on how warm it is today - as compared to the past - be made? How can it be so easily chalked up to just human activity?

Some of those "uncertainties" are quite perplexing when considered over even longer periods of time. There have been noted discrepancies between atmospheric CO2 levels and proxy temperature measurements dating back as far as 250,000 years (these measures employ the same methodology as those used to collect data presented in the 2006 report). It has been noted that, in the past, high CO2 concentrations appeared when there were low temperatures, and sometimes the CO2 levels were low when the temperatures were found to be high.

H. Fischer and M. Wahlen. 1999. "Ice Core Records of Atmospheric CO2 around the Last Three Glacial Terminations," Science 283, 1712-1714.


Assertions linking human-caused warming with a rise in oceans also has debate surrounding it. Oceans don't rise in a uniform fashion, but respond to local changes in temperature and winds. 1993 was the first year in which complete satellite data was collected from around the globe. The data examined from 1993 to 1998 actually showed sea levels falling in many regions around the world.

Cabanese, C., et al. 2001. Sea level rise during the last 40 years determined from satellite and in situ observations. Science 294: 840-42

Evidence for temperature variation derived from proxy measurements suggest that about 1,000 years ago regions of earth were substantially warmer than they are today. By the fourteenth century, the Little Ice Age had begun, one of a number of natural variations in climate. Recent warming is viewed by some as a recovery from this era, a recovery that may still be taking place today.

H.H. Lamb. 1985. Climate History in the Modern World. New York, NY: Methuen.

While the post-Little Ice Age warming was not caused by human activity, that warming created a more comfortable environment, gradually improved farming conditions that, in turn, allowed for population growth. In other words, it was a natural warming trend that offered benefits to human populations that supported population growth at that time.


Consensus so they say, but hardly completion of the debate.

 

[ganjavih]

As you rightly suggested earlier, science is constantly evolving. That's why I cited recent articles that review the entire body of evidence. As of today, there is a consensus within the scientific community. I don't have the expertise to judge the quality of their evidence but if you have good reason to believe their science is flawed and you think you can prove it, perhaps you should make a submission to one of these journals.

 

[EnviroTO]

If more scientists in the field of climate studies believe there is an issue than don't believe there is an issue then I'm inclined to support moves that support the findings of a greater number of scientists. I'm not exactly sure how this majority of scientists is being measured though. I don't think the scientific research should stop on the topic though and if in twenty more years they find out that their assumptions are wrong then good news, we are more efficient and have a huge reserve of oil ready to burn.

In many areas of science there is not absolute certainty but that uncertainty is usually dealt with by choosing a path which attempts to limit risk. In drug research it means testing on lab animals even though lab animals aren't fully representative of humans, then limited tests on humans, and then larger trials, etc. Drugs are allowed and prevented from use with only a very limited understanding of the human body and a drug allowed today might be pulled of the shelf tomorrow and a drug prevented today might end up being permitted in the future. The Canada health guide has changed over the years because the research continues but it doesn't stop recommendations being made. In engineering soil that will be built on top of is collected in drilling samples and tested in the lab and the results are purely by observation of how the sample behaves, it isn't an exact science and it is possible that there could be something missed since drilling does not occur on every square inch of the site... however they simply try and determine a worst case scenario and factor it into their design.

If a majority of climatologists currently believe that climate change is real, that CO2 gas is a primary cause, and that to mitigate the risk of the polar ice caps melting and drowning cities and causing drought there should be changes to the CO2 emission levels then I think that is the course of action we should take. The science shouldn't stop but making educated guesses is better than making an uneducated guess or simply rolling a dice. The argument that something is not fully understood can be put up as an obstacle to almost every public endeavor... art, transit, government, healthcare, social programs, law, etc... is all debatable and in the end we simply need to present the arguments and make a decision regardless of the fact there isn't 100% certainty. In matters of climatology I think the most important people to vote or come to consensus are climatologists rather than the public at large. After there is an understanding that the scientific community believes in something it is then time for people and government to decide what they are going to do about it. The only time you can be truly certain humanity will be wiped out is at the point nobody is left to report the findings.