Mars and Earth: Both experiencing global warming?

[newtonian]

earthseed - Well, Smithsonian noted researching sea level rise is hard to research - so I guess it is hard information.<br /><br />Just kidding.<br /><br />Actually, I have found that "Awake!' does not publish reports like this without first determining reliability - though the publishers have used terms like "scientists say." That, of course, is taken with a grain of salt, since we know scientific reports are subject to error.<br /><br />Tuvalu involves a number of islands. If building an airport was the cause of sinking, it would be more pronounced on the island where the airport was built.<br />This is not the case, however<br /><br />My area, SE Louisiana, may be sinking, news reports indicate this. No mention in the local news that I noticed that implicated oil removal as a cause - however your suggestion to that effect is plausible, as I do know examples of where removal of groundwater has caused land to sink.<br /><br />Oil is an important industry here so it is not likely this cause would be publicized here. It would not be economically advantageous to stop pumping out oil, etc., etc.<br /><br />There are probably a number of causes - however, coastle erosion has become increasingly evident over a very large area and obviously all coastlines are not sinking - so I suspect sea level rise is part of the problem.<br /><br />It makes sense, too. Increased ocean temperature would cause thermal expansion which would cause a rise in sea level.<br /><br />And melting of land ice would also cause a rise in sea level.<br /><br />It also makes sense that countries that do not want to lower emissions as agreed on at the Kyoto protocol would encourage circulation of reports denying sea level rise, etc., etc. Those are powerful countries!<br /><br />Remember the "scientific" reports sponsored by tobacco companies? <br /><br />I still need to stidy yoor link - whcih I will respond on later.<br /><br />I will also search for "hard" information - both meanings!

 

[newtonian]

earthseed - OK, I examined your link as follows:<br /><br />Earthseed - From your link to “Science,” 10/26/01, p. 840 ff.:<br /><br />“Sea Level Rise During Past 40 Years Determined from Satellite and in Situ Observations,” by<br />Cecile Cabanes, Anny Cazenave, Christian Le Provost.<br /><br />The article shows that sea level is rising, but the rate was overestimated.<br /><br />The overestimated rate they are talking about:<br /><br />“The 3.2 +- 0.2 millimeter per year global mean sea level rise observed by the<br />Topex/Poseidon satellite over 1993-98 is fully explained by thermal expansion<br />of the oceans. For the period 1955-96, sea level rise derived from tide gauge<br />data agrees well with thermal expansion computed at the same locations.” p.840<br /><br />In our recent 7/22/05 Awake! On the increase of natural disasters, an editorial in Science, likely more recent, is quoted:<br /><br />“According to an editorial in the journal “Science,” “sea levels have risen 10-20 centimeters [four to eight inches] in the past century, and more is in store for us.”” - “Awake!,” 7/22/05, p. 6.<br /><br />Our chart for the metric system units of length:<br /><br />Prefix Means Examples<br />Kilo 1,000 times kilometer = 1,000 meters<br />Hecto 100 times hectometer = 100 meters<br />Deca 10 times decameter = 10 meters<br />Deci 1/10 of decimeter = .1 meter<br />Centi 1/100 of centimeter = .01 meter<br />Milli 1/1,000 of millimeter = .001 meter<br /><br />So, to compare with the same unit, Science 10/26/01 old estimate: .32 centimeters per year.<br />The Awake quote of the Science editorial: -- 10-20 centimeters per 100 years.<br /><br />100 x .32 = 32 centimeters per 100 years.<br /><br />Clearly the sea level rise overestimate was corrected down by about one half.<br /><br />The Tuvalu estimate in Awake from Smithsonian, namely .22 inches annually over a recent decade, involves conversion from the metri

 

[earthseed]

There is no question that global sea levels are rising. It was the first thing I said in my original post. My point was, and remains, that there are local variations, and in the case of the area around Tuvalu sea levels are actually falling. There is still some uncertainty in this, but Tuvalu is a poor example to use for the effects of global warming.<br /><br />About the meaning of the Science article: Figure one suggests sea level is rising 3.2 mm/yr, equivalent to 32 cm per century. But look closely at figure 3, shown below. The period covered by figure 1 turns out to be the upward part of a decade long cycle. All three methods show a linear rise is sea level over the past forty years, although with different rates. The largest value, from tidal guages, shows 8 cm over the 40 years.<br /><br />Another conclusion is that sea level rise can be explained entirely by thermal expansion. That means water from melting glaciers is being offset by something else, probably increased snowfall over Greenland and Antarctica. Antarctica is actually getting slightly cooler, and its ice cap is growing.<br /><br />They mention in passing the IPCC estimate that<blockquote><em>The least certain contribution is the change in terrestrial water storage that results partly from human activities, which is in the range of –1.1 to + 0.4 mm/year with a median value of -0.35 mm/year.</em></blockquote>This uncertainty is a large portion of the total.

 

[paulolearysp]

So, if we assume from that report that the sun is responsible for 10-30% of global warming on earth, it's probably responsible for 100% of the global warming observed on Mars.<br /><br />Newtonian wrote:<br /><br />But a 2003 study by a group headed by Columbia's Richard Willson, principal investigator of the ACRIM experiments, challenged the previous satellite interpretations of solar output. Willson and his colleagues concluded, rather that their analysis revealed a significant upward trend in average solar luminosity during the period. <br /><br />and: <br /><br />Applying their analytical method to the solar output estimates by the Columbia group, Scafetta's and West's paper concludes that "the sun may have minimally contributed about 10 to 30 percent of the 1980-2002 global surface warming." <br />

 

[earthseed]

I would assume solar output was the only thing affecting temperature on Mars, at least in the short term. A change in the tilt of its axis could affect it in the longer term.

 

[jatslo]

Microwave emissions from the satellites could melt the polar ice on Mars over the years. This is especially true with the deep ground penetrating type that detects liquids. NO BS!

 

[newtonian]

earthseed - We basically agree, except about Tuvalu.<br /><br />You seemed to have missed the point in the Smithsonian article.<br /><br />The reduction in sea level was temporary, due to El Nino.<br /><br />When account for that and other effects the scientists researching the matter found that Tuvalu sea level was rising, not falling, and a rate of .22 inches per year (22 inches per 100 years).<br /><br />See my above posts and reread that portion of the Smithsonian article if you still don't see this.<br /><br />Thank you for posting that excellent diagram - it was actually the one I was referring to!<br /><br />Please note that is discussing the global mean, not the localized sea level at Tuvalu (I thnk you have noted that).<br /><br />Did you note that .22 inches per year for Tuvalu sea level rise (on average, not just the El Nino period) was stated to be in agreement with the global mean sea level rise also?<br /><br />I think what we have here, btw, is not a disagreement but misunderstandings.

 

[newtonian]

paulolearysp - Uh oh! Your post makes sense - I did actually note that also, but got sidetracked on the above tangent.<br /><br />Of course, if solar radiation is increasing, all planets would have some global warming.<br /><br />Which then begs other questions:<br /><br />1. Why is solar radiation increasing? Is there some long term cycle we don't know about?<br /><br />2. Is Venus experiencing further global warming?<br /><br />3. Is Mercury experiencing global warming (no atmosphere?)

 

[earthseed]

Well, Newtonian, I am unconvinced either way about Tuvalu. I re-read the Smithsonian article carefully. You have one scientist claiming sea level is rising there, contradicting Australia’s National Tidal Centre. Then there is the 0.22 inches per year from the tidal station, which cannot distinguish between a rising ocean and a sinking island. An El Nino only lasts two years, so how can it have any effect over a decade?<br /><br />On the other hand, the Science article I quoted claims sea level decline over 40 years (around Tuvalu). Of course, this may be incorrect as well, who knows. I need better information before I pass judgement.

 

[earthseed]

To return to the original topic of this thread, here is a comprehensive article at RealClimate.org on this issue. They suggest changes in Martian climate have nothing to do with solar intensity.<blockquote><em>A couple of basic issues first : the Martian year is about 2 Earth years (687 days). Currently it is late winter in Mars's northern hemisphere, so late summer in the southern hemisphere. Martian eccentricity is about 0.1 - over 5 times larger than Earth's, so the insolation (INcoming SOLar radiATION) variation over the orbit is substantial, and contributes significantly more to seasonality than on the Earth, although Mars's obliquity (the angle of its spin axis to the orbital plane) still dominates the seasons. The alignment of obliquity and eccentricity due to precession is a much stronger effect than for the Earth, leading to "great" summers and winters on time scales of tens of thousands of years (the precessional period is 170,000 years). Since Mars has no oceans and a thin atmosphere, the thermal inertia is low, and Martian climate is easily perturbed by external influences, including solar variations. However, solar irradiance is now well measured by satellite and has been declining slightly over the last few years as it moves towards a solar minimum.<br /><br />Globally, the mean temperature of the Martian atmosphere is particularly sensitive to the strength and duration of hemispheric dust storms. Large scale dust storms change the atmospheric opacity and convection; as always when comparing mean temperatures, the altitude at which the measurement is made matters, but to the extent it is sensible to speak of a mean temperature for Mars, the evidence is for significant cooling from the 1970's, when Viking made measurements, compared to current temperatures. However, this is essentially due to large scale dust storms that were common back then, compared to a lower level of storminess now. T</em></blockquote>

 

[paulolearysp]

It seems like we're going to need a lot more data before we can really determine whether Mars is warming up or if it's just a cyclical issue. Maybe we need to start taking pictures of the poles on a quarterly basis? Or maybe the scientists have more important questions to answer or better ways of determining this.<br /><br />I think if it's hard to determine what is happening to mars, which has a relatively simple climate, it's even harder to look at earth and it's global warming. Look how long it took us to understand El Nino!

 

[earthseed]

According to the article Did the Sun hit record highs over the last few decades? at RealClimate.org, solar output has not changed much since 1950. This contradicts recent estimates that 10 to 30% of recent warming on Earth is solar caused.

 

[nexium]

The one degree f = 0.6 degree c near surface air temperature rise found over selected periods up to 150 years is not much, so 30 % of it is not much.<br />We should not multiply the few mm of ocean rise over 4 years by 25 to get the increase for a century as there is lots of evidence it is not a linear rise, and a bit of evidence that falling sea level occurs more often than rising sea level.<br />A possible explanation is: Melt water with little salt, enters the ocean at about 5 degres c, mixing with minus 1 to +1 degree ocean water containing half the usual salt. The mixing is partial, so some of it is 4 degrees c which sinks to the bottom because the maximum density of water occurs at 4 degrees c. Perhaps 40% of all the water in the ocean is at 4 degree c (at the ocean bottom) and this has increased to 41% in the last 40 years due to rapid melting of ice in the Arctic zone and near by. The increased volume of water at it's maximum density has off set, the increased volume of warmer water close to the surface. Is anyone checking water temperatures a kilometer below the surface? Neil

 

[earthseed]

Back from Mars, I would like to return to Tuvalu (clearly the most important place on Earth) one last time. Ocean levels may be falling there, in contrast to most of the world, but sea surface temperatures seem to be following the script, as seen in the graph below.

 

[aj102]

Regarding contrarians highlighting the fact that only a small percentage of greenhouse gas emissions are "man-made": This small percentage (currently about 4.5%), is of annual emissions, and is resulting in an <i>accumulation</i> of several gigatons a year, above natural absorption. And of course, there are feedback effects that result from that as well. http://globalwarmingtruth.org notes that this contribution is significant, "as evidenced by the observed rise in atmospheric concentration (virtually all of which is anthropogenic)". Further down the page is a link to realclimate.org, where they discuss this. They briefly mention warming on Mars as well, something I've seen skeptics use to mislead.<br /><br />As for the 2003 Tans estimate that 60% of the warming is due to humans, I would say that's now looking a bit conservative, considering the relatively small percentages being attributed to natural causes.<br /><br />The 10-30% solar study is also discussed at http://www.realclimate.org/index.php?p=192#comment-4756 and http://www.realclimate.org/index.php?p=192#comment-4810<br />Sigurdsson notes that under this study, you can get to 30% "if you push it".<br />

 

[nexium]

My guess is 4.5% is way high for man's contibution to green house gas emissions. Does anyone have believable details?<br />Some accumulation is reasonable, but why several gigatons? Feed back is as likely to reduce as it is to increase: Does anyone have details?<br />In my opinion the advocates of global warming have been caught in far more lies and worse exaggerations than the skeptics. The solar constant may have increaced by 1% in the last 50 or 100 years:10% = no way! Neil

 

[newtonian]

aj102 - Thank you for the links.<br /><br />Interesting vocabulary - let me try to translate what you mean - please correct me if I misunderstand:<br /><br />1. Contrarians - Those who disagree global warming is occurring - or more likely those who disagree the global warming is dangerous and with a significant portion being man-made.<br /><br />2. Greenhouse gas emissions - you are referring to more than carbon dioxide (CO2) - e.g. methane (CH4). Would you like to list these gases in order of importance to global warming? My understanding is that CO2 increase is the most significant contributor to man-caused global warming.<br /><br />3. Anthropogenic - man-caused (anthro- man; genic - to give birth to (cp. gene, generate, genus, etc.)<br /><br />4. I have personally noticed the solar radiation increase on my skin - but I suspect much of this is due to ozone depletion ( a certain percentage is world wide - not just limited to ozone holes).<br /><br />Concering Mars - I suspect that some solar increase is making matters worse.<br /><br />Concerning the increase in cold deep waters offsetting the increase in surface ocean temperatures - that is alarming - as it would only temporarily slow the rise in sea level!!!!!<br /><br />And, concerning the dangers of global warming - please do not ignore hurricane Wilma which went from 970 mb in pressure yesterday at 5 PM to about 882 mb at 5 AM this morning - an unprecedented drop in pressure - and, as a result, it is now a strong cat 5 - estimated to be 175 mph near its tiny eye!

 

[newtonian]

nexium - In the scientific debate on the causes of global warming, please do not lump all advocates of global warming together - ditto skeptics.<br /><br />There are those who exaggerate for various reasons, including political agendas, on both sides of the debate.<br /><br />But there are also honest disagreements in interpretations of the details.<br /><br />You are correct that one must determine the details, as most posters on this thread seem to want to do - i.e. to determine the truth.<br /><br />Meanwhile, however, please do not ignore hurricane Wilma. <br /><br />Note my above posts where I included quotes and lilnks to reliable sources.<br /><br />I will post research on the increase in greenhouse gases and the increase in global temperatures - which clearly are related albeit global systems are very complex.

 

[newtonian]

Neil: Concerning the increase in greenhouse gases and effects:<br /><br />Here is another quote to compliment those above (note above our more recent quote from Smithsonian documenting the rise in sea level due to global warming; etc.):<br /><br />“Effect of Pollution<br /><br />In the mid-19th century, humans began to burn ever larger amounts of coal, gas, and oil, adding large amounts of carbon dioxide to the atmosphere. At that time the amount of this trace atmospheric gas was about 285 parts per million. But as a result of man’s increased use of fossil fuels, the amount of carbon dioxide has reached over 350 parts per million. What has been the consequence of more of this heat-trapping gas being in the atmosphere?<br /><br />Many believe that the increase of carbon dioxide levels is what has caused the rise in earth’s temperatures. Other researchers, however, say that global warming is due particularly to our sun’s variability—that the sun has been emitting greater energy in recent times.<br /><br />Whatever the case, the decade of the 1980’s was the hottest since records started to be kept in the mid-19th century. “The trend continued into this decade,” reports the South African newspaper The Star, “with 1990 the hottest year on record, 1991 the third warmest, and 1992 . . . the tenth warmest year in the 140-year record.” The slight decrease over the past two years is attributed to dust ejected into the atmosphere when Mount Pinatubo erupted in 1991.<br /><br />The future effects of the increase of temperatures on earth are hotly debated. But one thing global warming evidently has done is to complicate the already difficult task of weather forecasting. New Scientist notes that wrong forecasts “may be increasingly likely as global warming changes the climate.”<br /><br />Many insurance companies fear that global warming will make their policies unprofitable. “Faced with [a] spate of misfortunes,” admits The Economist, “some reinsurers are reducing their exposure to natural di

 

[aj102]

There might be some confusion over the percentage of CO2 vs. the percentage of total GHG emission, but the IPCC's "The Science of Climate Change" noted that fossil fuels account for 3.4-3.8% of the "annual flows of carbon in the atmosphere"- and that was in 1995. I wish I could remember where else I've seen the 4.5% figure - perhaps I'll look into it further at some point.<br /><br />Last I read, though, total human CO2 output was about 7 gigatons/year, and just over half of that is absorbed, including by the oceans. In any case, if CO2 is 30+% above pre-industrial levels (and rising), and most of that increase is from humans, I would say that's a pretty significant. Then there's this, and this table has some interesting info on greenhouse gas levels (including methane) and their contribution to increased radiative forcing.<br /><br />And where are the details that support the claim "Feed back is as likely to reduce as it is to increase"? It's pretty well established that levels of methane, water vapor, and even CO2 will rise in response to warming, which negative feedbacks apparently aren't keeping pace with (if anything, they're being attenuated - note the ablation of reflective ice). One might point to clouds as a cooling influence, but of the extra water vapor from global warming, how much actually condenses into additional cloud cover when temps (and thus, atmospheric moisture capacity) are elevated? And how much of any extra cloud cover would have a net cooling effect? This suggests we shouldn't bet the farm on clouds.<br /><br />So what negative feedbacks actually show signs of kicking in and significantly reducing

 

[newtonian]

aj102 - There is the geologic carbon cycle - clearly being overwhelmed by man-made CO2 emissions.<br /><br />That cycle involves oceans as a CO2 sink, i.e. CO2 dissolves in ocean water to produce H2CO3 which separates into ions. The CO3 ion combines with Calcium to produce limestone. Other carbonates also precipitate out via CO3 combining with Potassium (K) and Sodium (Na) ions.<br /><br />BTW, earth's carbonates imply an ancient CO2 atmosphere with CO2 content similar to Venus' today.<br /><br />Venus is a dramatic warning of what can happen as a result of a runaway greenhouse effect.<br /><br />And Venutian clouds do not stop the vicious cycle, which ultimately released virtually all CO2 from carbonates.