tag:blogger.com,1999:blog-49237775267675247112024-03-13T20:04:45.724-07:00Our Earth in 2050David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-4923777526767524711.post-72138409353336659992010-02-16T04:56:00.000-08:002010-03-29T08:37:40.891-07:00Final Forecast for Our Earth in 2050<span style="font-family:arial;"><span style="font-weight: bold;">We and our planet are going to be in for serious and probably irreversible changes -- only 40 years from now.</span><br />The preceding sections give us the following picture for our planet in the year 2050, under the "business as usual" response -- the response favored by global warming skeptics.<br /><br />1) In our straightforward projection, human activities have increased the <a href="http://greenphysicist2.blogspot.com/2010/02/atmospheric-carbon-dioxide-levels.html"><span style="font-weight: bold;">atmospheric carbon dioxide levels to </span><span style="font-style: italic; font-weight: bold;">twice</span><span style="font-weight: bold;"> the pre-industrial level</span>.</a> This is twice the maximum interglacial levels recorded over the last 1.3 million years. An increase of CO2 of this magnitude has had a large, undeniable effect on the temperature of the planet.<br /><br />2) From the CO2 increase alone, <span style="font-weight: bold;"><a href="http://greenphysicist2.blogspot.com/2010/02/increase-in-global-temperature.html">the global average surface temperature of our planet has increased 2.5 degrees Centigrade</a> </span>(4.5 degrees Fahrenheit) by 2050. This is relative to the 1910 mean global minimum. Relative to the average 1980-99 global mean (the reference level in the <a href="http://greenphysicist2.blogspot.com/2010/02/tipping-points.html">tipping point table</a>) the global rise would be about 2.0 degrees. A rapid rise of this magnitude has had many effects on the Earth's non-linear, highly driven weather system.<br /><br />3)<span style="font-weight: bold;"> There has been an increase in storms and in extreme weather of all kinds</span>. The effects on storms have included increased power in cyclones and hurricanes. Coupled with a rise of about a meter in sea level, storm surges have caused extensive damage to coastal areas around the world. Several island nations have ceased to exist, as have some low-lying urban regions in Florida, the Gulf region and the Atlantic coast, to mention only the U.S. areas affected.<br /><br />4) <a href="http://greenphysicist2.blogspot.com/2010/02/permafrost-melts-earth-heats-even-more.html"><span style="font-weight: bold;">The temperature rise in the Arctic has been about twice that of the global mean</span></a>. The permafrost has been melting at a huge rate, leaving the tundra scattered with shallow lakes. Enormous quantities of methane have come from these lakes and from the bottom of the warming Arctic Ocean, enough to cause an increase in the rate of rise of the global mean temperature. This effect alone could potentially contribute another 0.5 degrees of warming by 2050.<br /><br />5) <span style="font-weight: bold;"><a href="http://greenphysicist2.blogspot.com/2010/02/rise-in-sea-level.html">The Greenland ice sheet is well into its melting,</a></span> resulting in a total sea level rise of more than a meter (39") causing extensive damage to coastal areas, including shoreline erosion, loss of wetlands, agricultural areas and living areas.<br /><br />6. <span style="font-weight: bold;">There has been extensive disruption of agriculture</span> around the world due to climate change, including long-term droughts in some areas and increased flooding and storm damage in others. </span><span style="font-family:arial;"> </span><span style="font-family:arial;">While there have been some new opportunities for food production in areas that were formerly too cold or too dry, these opportunities have not been sufficient to make up for losses elsewhere.<br /></span><br /><span style="font-family:arial;">7) <a href="http://greenphysicist2.blogspot.com/2010/02/tipping-points.html"><span style="font-weight: bold;">The summer Arctic sea ice is now completely gone</span></a>, resulting in further changes to the Northern climate and ecosystems.<br /><br /></span><span style="font-family:arial;">8. With a 2.5 degree rise in global temperature, <span style="font-weight: bold;"><a href="http://greenphysicist2.blogspot.com/2010/02/tipping-points.html">the Earth now stands on the precipice of several additional, potentially catastrophic tipping points</a>.</span> </span><span style="font-family:arial;">These include: melting of the West Antarctic ice sheet, the diversion of the Atlantic circulation, the increase in strength of the El Nino phenomena, and the loss of most of the Amazon and boreal forests.<br /><br /><span style="font-weight: bold;">It is clear that it would be wise</span> to avoid these additional catastrophes by an immediate halt to CO2 production -- but with most of the world's people on the brink of starvation, their immediate survival is more important to them than making sacrifices by stopping the use of fossil fuels, trees for firewood for cooking, etc.<br /><br /><span style="font-weight: bold;">A</span><span style="font-weight: bold;">fter forty years of business as usual, it is now too late to make needed changes</span>. The world, its peoples and resources strained to the breaking point, can now only continue to careen forward, straight into the teeth of these new, catastrophic changes.</span><span style="font-family:arial;"><br /><br /><span style="font-weight: bold;">Our forecast is worse than that of the IPCC</span><br /></span><img src="file:///C:/DOCUME%7E1/Owner/LOCALS%7E1/Temp/moz-screenshot.png" alt="" /><img src="file:///C:/DOCUME%7E1/Owner/LOCALS%7E1/Temp/moz-screenshot-1.png" alt="" /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://2.bp.blogspot.com/_vRsObFw-TN0/S4ad2tuTAcI/AAAAAAAAASw/2BxUJctmO94/s1600-h/IPCC+report+trimmed+final.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 439px; height: 333px;" src="http://2.bp.blogspot.com/_vRsObFw-TN0/S4ad2tuTAcI/AAAAAAAAASw/2BxUJctmO94/s400/IPCC+report+trimmed+final.jpg" alt="" id="BLOGGER_PHOTO_ID_5442210763036099010" border="0" /></a><span style="font-family:arial;">As mentioned in the introduction, the International Panel on Climate Change (IPCC) has been forced to produce cautious, conservative reports. Their 2007 report gave the projections above for the surface temperature through the rest of the century. Our projection of a temperature rise of 2 to 2.5 degrees (relative to the baseline of this graph) is clearly at the very upper range of their forecasts. Why?</span><br /><br /><span style="font-family:arial;">The IPCC forecasts make the unwarranted assumption that nations and people will try to do the right thing</span><span style="font-family:arial;">,<span style="font-weight: bold;"> </span>and hold back some of their carbon dioxide emissions. Equivalently, they assume that the world's economy will rise at a slightly lower rate than the rate that we have derived by simply fitting the most recent CO2 rise.</span><br /><br /><span style="font-weight: bold;font-family:arial;" >We have not made any such rosy predictions. </span><span style="font-family:arial;"> We have just extrapolated the present trends forward without any such decrease in rate. We used the rate that fits the CO2 data, a 2.2% annual growth rate in CO2 production, a rate that is securely determined. You can even directly see from the data in the graph above (the black line) that the IPCC would get the same answer that we did if they made the same "business as usual" assumption.</span><br /><br /><span style="font-weight: bold;font-family:arial;" >We will stick by our prediction. The mean global temperature will be up more than 2 degrees by 2050. We will put money on it.</span><span style="font-family:arial;"><br /><br /><br />/<br /></span>David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.com0tag:blogger.com,1999:blog-4923777526767524711.post-76088976475392760812010-02-11T22:05:00.000-08:002010-03-28T17:52:46.016-07:00Permafrost melts and Earth heats even faster<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://3.bp.blogspot.com/_vRsObFw-TN0/S3T1VGv4D3I/AAAAAAAAAP0/FVJSasmNMNA/s1600-h/Thermokarst+Lakes+forming.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 344px; height: 242px;" src="http://3.bp.blogspot.com/_vRsObFw-TN0/S3T1VGv4D3I/AAAAAAAAAP0/FVJSasmNMNA/s400/Thermokarst+Lakes+forming.jpg" alt="" id="BLOGGER_PHOTO_ID_5437240393080508274" border="0" /></a><span style="font-family:arial;">About 20% of our Earth's land surface is frozen all year long, a layer of ice and plant material tens of meters thick called permafrost. Or it </span><span style="font-style: italic;font-family:arial;" >was</span><span style="font-family:arial;"> permanently frozen, until recently. The Arctic region is heating up at about twice the rate of the equatorial regions, so the southernmost, upper layers of permafrost have begun thawing. As this ice melts, the ground subsides, and often shallow lakes fill up the depressions with water from the melted ice (photo above). Bacteria then start to decompose the plant material.</span><br /><br /><span style="font-family:arial;">But these bacteria are mostly at the bottom of lakes, where there is little oxygen. Because of the anaerobic conditions, they can only partly decompose the plant and animal remains they are eating. The decomposition, instead of going all the way to produce water and carbon dioxide, stops half way and produces methane instead. The methane gas, also known as "swamp gas," bubbles to the surface and escapes into the atmosphere.</span><br /><br /><span style="font-family:arial;">This is a problem. Methane is 8 times more powerful a greenhouse gas than carbon dioxide. If enough methane escapes to affect the greenhouse warming, our planet heats even more. More methane is then released, and so it goes, into a runaway process. As discussed in the previous section, the permafrost melting constitutes a "tipping element." The global temperature at which an irreversible runaway starts is called the "tipping point" temperature.</span><br /><br /><span style="font-family:arial;">It is not certain what the tipping temperature is for the permafrost system. We may have already passed it, or it could be 1 or 2 degrees higher than at present. In the previous section, it was noted that 1/3 to 1/2 of the permafrost was estimated to be within 1 to 1.5 degrees of melting at the present time. This fact suggests that a reasonable estimate would place the permafrost tipping temperature at about 0.75 degrees above the present mean global temperature. This is a conservative estimate, given that most models predict that the Arctic temperature will rise at about twice the rate of the mean.</span><br /><br /><a style="font-family: arial;" onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://4.bp.blogspot.com/_vRsObFw-TN0/S3VY3qwO5BI/AAAAAAAAAQE/VTobJBfRQ6w/s1600-h/PermafrostMeltingGraphFinal.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 372px; height: 237px;" src="http://4.bp.blogspot.com/_vRsObFw-TN0/S3VY3qwO5BI/AAAAAAAAAQE/VTobJBfRQ6w/s400/PermafrostMeltingGraphFinal.jpg" alt="" id="BLOGGER_PHOTO_ID_5437349838512382994" border="0" /></a><span style="font-family:arial;">The time that the transition will take depends on several factors. Even after it reaches zero degrees Centigrade, it takes heat to thaw ice. Once the process begins, the heat transfer from sun and air to permafrost layers is complicated by the growing plants and lakes dotting the landscape. It has been estimated by V. Alexeev that, including all the factors, the thawing permafrost could contribute an additional 0.32 degrees Centigrade to the global temperature by 2100.</span><br /><br /><span style="font-family:arial;">Such estimates agree well with the measured ground temperatures as shown above. Note that, except for a brief period near 1999, the trend has been steadily upward in recent years. The horizontal dotted line is at zero degrees Centigrade, the melting point for ice.</span><br /><br /><a style="font-family: arial;" onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://4.bp.blogspot.com/_vRsObFw-TN0/S3iLiqhH2eI/AAAAAAAAAQ0/SFVRFkGrIQI/s1600-h/__TotalTemp+RisePermafrostMelt.jpg"><img style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer; width: 279px; height: 320px;" src="http://4.bp.blogspot.com/_vRsObFw-TN0/S3iLiqhH2eI/AAAAAAAAAQ0/SFVRFkGrIQI/s320/__TotalTemp+RisePermafrostMelt.jpg" alt="" id="BLOGGER_PHOTO_ID_5438249977694902754" border="0" /></a><span style="font-family:arial;">The graph on the right shows the expected global temperature with the permafrost tipping element added. This is the same graph as was used to extrapolate the global temperature previously, except that now the red line shows the additional heating due to permafrost thawing. The tipping point for this element, relative to the 1988-99 average, is taken to be about 1 degree Centigrade. This may seem low, but remember that this refers to the increase in the </span><span style="font-style: italic;font-family:arial;" >global</span> mean temperature, and most models predict that the Arctic temperature rise will be about twice that of the mean.<br /><br /><span style="font-family:arial;">This graph suggests that the tipping point will occur about 2030, only 20 years from now. The increase shown in this figure is schematic, and not intended as a prediction of the actual magnitude of the temperature rise. No matter the magnitude of the rise, however, with the transition fully underway by 2050 the main effect is seen to be a significant increase in the </span><span style="font-style: italic;font-family:arial;" >rate</span><span style="font-family:arial;"> of rise of the global temperature -- and the expected rate is already mind-boggling enough.</span><br /><br /><span style="font-family:arial;">Recent observations by an international scientific team suggest that the problem may actually be worse than previously thought. A large section of the Arctic Ocean sea floor is showing signs of instability and is already venting vast quantities of methane. The current rate is equal to that coming out of all the rest of the world's oceans. Any increase in the Arctic Ocean temperatures will only increase the outflow. In combination with the loss of summer sea ice, these findings suggest that methane release from the Arctic may reach a tipping point well before 2050.</span><br /><br /><span style="font-family:arial;">Finally, the forecast: </span><a style="font-family: arial;" href="http://greenphysicist2.blogspot.com/2010/02/our-earth-in-2050.html">Earth in 2050</a><span style="font-family:arial;">.</span><br /><span style="font-weight: bold;font-family:arial;" ><br />DETAILS<br /><br /></span><span style="font-family:arial;">The photo at top (from </span><a style="font-family: arial;" href="http://www.treehugger.com/2007/09/16-week/">treehugger.com</a><span style="font-family:arial;">.) shows a view of "thermokarst" lakes, illustrating the huge number of shallow lakes which form as permafrost melts.<br /><br />The graph of temperature at different depths versus time is from the </span><a style="font-family: arial;" href="http://www.greeninstitute.net/">Green Institute</a><span style="font-family:arial;"> website.<br /><br />Estimates of permafrost melting rates are from the article by K. W. Anthony referenced in the previous section.<br /><br />Recent measurements of melting of the permafrost on Arctic seafloor was reported in </span><a style="font-family: arial;" href="http://www.sciencedaily.com/releases/2010/03/100304142240.htm">Science Daily, March 5, 2010</a><span style="font-family:arial;">.<br /><br />Current estimates are that the total carbon released from Arctic permafrost melting and from the Arctic ocean bottom could be up to<span style="text-decoration: underline;"> </span><a href="http://www.sciencedaily.com/releases/2009/10/091014144729.htm">25% of the total</a> of Earth's carbon sink.<br /></span>David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.com0tag:blogger.com,1999:blog-4923777526767524711.post-90137385451005118532010-02-08T07:58:00.000-08:002010-03-28T17:48:33.793-07:00Dangerous tipping points loom ahead<span style="font-weight: bold;font-family:arial;" >Some dangerous tipping points may have already been passed, many more lie just ahead.</span><br /><span style="font-family:arial;">The problem of forecasting the future climate -- even for so close a date as 2050 -- is made more difficult because of the existence of "tipping points" in our climate system. More important, the transitions that occur when tipping points are reached make our future extremely dangerous. It is important to know more about them. The way a tipping point functions can best be understood using the concept of feedback loops.</span><br /><br /><span style="font-family:arial;">Feedback loops are classified as "positive" and "negative." A positive feedback loop is one that amplifies a small change in the system, making it have a larger effect than it would otherwise. A little positive feedback can be good, or your stereo amplifier wouldn't function. But too much can be bad, as when your speakers feed back the output signal back into the input signal -- a microphone -- and you get this loud, unpleasant squeal. In terms of global warming, positive feedback is nearly always bad. What would be a small change in global warming can be amplified into a bigger change as a result of positive feedback.</span><br /><br /><span style="font-family:arial;">Negative feedback, on the other hand, reduces the effect of any change in the system. It provides system stability. In terms of global warming, "negative" feedback is almost always "good."</span><br /><br /><span style="font-family:arial;">Presently, the most important example of a tipping element involves permafrost melting. Permafrost is a layer of soil that remains frozen year round, even during summer when local air temperatures are well above freezing. If the permafrost begins to melt under anaerobic conditions, say at the bottom of a lake or the ocean, bacterial action produces methane. The methane bubbles to the surface and into the atmosphere. Methane is a very potent greenhouse gas, eight times more potent molecule for molecule than carbon dioxide. If the methane is produced in large enough quantities to affect the global climate, permafrost melting can become part of a runaway greenhouse effect. We would then say that the tipping point for permafrost melting would have occurred. This possibility seems increasingly likely and very dangerous, but so far has received little public attention.</span><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://1.bp.blogspot.com/_vRsObFw-TN0/S3MdFA4fqkI/AAAAAAAAAO0/JFyQB-V-KhA/s1600-h/TippingPoinFigureFinal.jpg"><img style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer; width: 279px; height: 214px;" src="http://1.bp.blogspot.com/_vRsObFw-TN0/S3MdFA4fqkI/AAAAAAAAAO0/JFyQB-V-KhA/s400/TippingPoinFigureFinal.jpg" alt="" id="BLOGGER_PHOTO_ID_5436721147139828290" border="0" /></a><span style="font-family:arial;">The diagram to the left shows in a schematic way how a tipping point transition occurs. The system starts out, in the front panel, symbolized as the red ball sitting in a bowl to represent stability of the initial climate. The shape of the blue surface is set by the parameters of the system. If one of the parameters, the global temperature for example, begins to increase, one can imagine that the blue surface moves upward. The bowl becomes more shallow, to indicate that the climate has become less stable. Eventually, the initial climate state becomes unstable, and the ball crosses into a new state as the tipping point is crossed. The new climate state, while stable, may have completely different characteristics from the initial climate state.</span><br /><br /><span style="font-family:arial;">A table is presented below which summarizes our current knowledge of tipping elements in the Earth climate system. The tipping elements in the table are listed in the order of the global temperature at which the tipping temperature is reached. The top four elements listed are those of most immediate concern, those with tipping transitions estimated to be within zero and a 2 degree increase in the present global temperature</span><span style="text-decoration: underline;"><span style="font-family:arial;">.</span><br /><br /></span><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://4.bp.blogspot.com/_vRsObFw-TN0/S3QpMHzhXmI/AAAAAAAAAPU/Qd8Iw4JCsBU/s1600-h/TippingTableF.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 453px; height: 394px;" src="http://4.bp.blogspot.com/_vRsObFw-TN0/S3QpMHzhXmI/AAAAAAAAAPU/Qd8Iw4JCsBU/s400/TippingTableF.jpg" alt="" id="BLOGGER_PHOTO_ID_5437015938373344866" border="0" /></a><span style="font-family:arial;">In this table, the columns in order list: the tipping element, the applicable direction of change (e.g., -rainfall means less precipitation), the global temperature at which the transition will occur (relative to the average 1980-99 value) , the approximate time in years that it should take to complete the transition, the overall impact of the transition, and references and notes listed in the "details" section below. Note that all of the transitions have potential ecological impacts, so these are not noted separately.</span><br /><br /><span style="font-family:arial;">Note in the table starting at the top line: </span><span style="font-weight: bold;font-family:arial;" >The permafrost</span><span style="font-family:arial;"> is already melting and may have already reached its tipping temperature. It will take a while to melt, as even at a constant temperature it takes some time to melt ice.</span><br /><br /><span style="font-family:arial;">There is some debate over whether the </span><span style="font-weight: bold;font-family:arial;" >loss of the Arctic summer sea ice</span><span style="font-family:arial;"> is a true tipping point, as it may be completely reversible (2, 3, 5). This is because the date at which the Arctic freezes over in the next winter does not appear to depend on how early it unfroze the last year. Whether a true tipping point or not, it is included in the table because the loss of ice in summer has already begun and this loss is having, and will have, a large effect on Arctic countries and on the northern ecosystem.</span><br /><br /><span style="font-weight: bold;font-family:arial;" >The loss of the ice cap in Greenland</span><span style="font-family:arial;"> has had a lot of attention in the press. While its tipping temperature will probably be reached soon, note that the transition time is estimated to be more than 300 years. This means that the 7 m rise in sea level associated with this transition will occur over many centuries, allowing considerable time for adaptation.</span><br /><br /><span style="font-family:arial;">This may not be true for impending </span><span style="font-weight: bold;font-family:arial;" >loss of the northern ice and snow cover</span><span style="font-family:arial;">. The absence of ice and snow year-round on the ground appears to constitute a true tipping point. Ice and snow, when present, reflect 90% of the energy from the sun right back into space. Therefore, ice and snow cover tends to stabilize the planet when it is in a ice age. </span><br /><br /><span style="font-family:arial;">If the ice cover starts to melt for any reason, however, the bare ground (or ocean) absorbs about 80% of the energy from the sun during the day. At night, the ground will re-radiate this energy as heat. Whether this heat escapes the earth or not depends on the greenhouse gas concentration in the atmosphere, among other things. If the greenhouse gas is at a high enough concentration, not all the gained heat is lost at night, and the bare ground warms and acts to accelerate the warming. A tipping point has been reached, and now the planet will warm until it becomes stable in an ice-free mode. In this case, the tipping point is actually set by the CO2 concentration itself.</span><br /><br /><span style="font-family:arial;">Note that all four of the top tipping points involve the Arctic. This is because the average temperature rise in the Arctic is about </span><a style="font-family: arial;" href="http://greenphysicist2.blogspot.com/2010/02/tipping-points.html">twice that at the equator</a><span style="font-family:arial;">. Therefore, the effect of global warming impacts this area first and hardest. The effect on the ice sheet covering west Antarctica is delayed somewhat beyond the northern effects for several reasons, e.g., location and depth of the sheet. </span><br /><br /><span style="font-family:arial;">The next dangerous tipping point is already underway: </span><a style="font-family: arial;" href="http://greenphysicist2.blogspot.com/2010/02/permafrost-melts-earth-heats-even-more.html">Melting permafrost</a><span style="font-family:arial;">.</span><br /><br /><span style="font-weight: bold;"><span style="font-family:arial;">DETAILS</span><br /><br /></span><span style="font-family:arial;">Notes and references for the table above:</span><br /><br /><span style="font-family:arial;">1) A. K. Walter (2009) "Methane: A menace surfaces," Scientific American, 301 (6) 68-75.</span><br /><span style="font-family:arial;">This article notes that 1/3 to 1/2 of the permafrost is within 1 and 1.5 degrees Centigrade of melting. The author predicts an </span><span style="font-style: italic;font-family:arial;" >additional</span><span style="font-family:arial;"> rise of 0.32 degrees Centigrade in global warming by 2100 due to methane release from melting permafrost.</span><br /><br /><span style="font-family:arial;">2) T. M. Lenton, et al. (2008) "</span><a style="font-family: arial;" href="http://www.pnas.org/cgi/ijlink?linkType=ABST&journalCode=pnas&resid=105/6/1786">Tipping elements in the Earth's climate system</a><span style="font-family:arial;">," Proc. Nat. Acad. Sci. (PNAS) 105, 1786-1793. First definition of a tipping element; summarizes tipping points derived from formal presentations, discussions and surveys at an international meeting of climate scientists. Especially see Table 1 in this article for further details.</span><br /><br /><span style="font-family:arial;">3) D. Notz (2009) "The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss," PNAS, 106, 20590-20595. Suggests that the loss of summer sea ice is reversible, but probably not the year-round loss of sea ice or complete loss of ice and snow cover on the ground.</span><br /><br /><span style="font-family:arial;">4) The rate of failure of the Indian monsoon is thought to increase because of warming but the probability cannot be directly related to the global temperature change (2).</span><br /><br /><span style="font-family:arial;">5) M. M. Holland, C. M Bitz, B. Tremblay (2006) "</span><a style="font-family: arial;" href="http://www.cgd.ucar.edu/oce/mholland/abrupt_ice/holland_etal.pdf">Future abrupt reductions in the summer Arctic sea ice</a><span style="font-family:arial;">," Geophysical research letters, </span><span style="font-weight: bold;font-family:arial;" >33</span><span style="font-family:arial;">, L23503</span><br /><br /><span style="font-family:arial;">Other tipping points and recent information can also be found in a </span><span style="text-decoration: underline;font-family:arial;" ><a href="http://www.sciencedaily.com/releases/2009/12/091209193728.htm">special tipping point section in <span class="blsp-spelling-error" id="SPELLING_ERROR_0">PNAS</span></a></span><span style="font-family:arial;"> (2009), edited and with an introduction by H. J. Schellnhuber.</span>David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.com0tag:blogger.com,1999:blog-4923777526767524711.post-89706014029443083082010-02-06T09:03:00.001-08:002010-03-28T17:42:57.370-07:00Sea levels rise as temperatures increase<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://2.bp.blogspot.com/_vRsObFw-TN0/S4U0txa7gkI/AAAAAAAAASI/Hvi_n8IU5SM/s1600-h/SeaLevelAndKatrina.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 349px; height: 215px;" src="http://2.bp.blogspot.com/_vRsObFw-TN0/S4U0txa7gkI/AAAAAAAAASI/Hvi_n8IU5SM/s320/SeaLevelAndKatrina.jpg" alt="" id="BLOGGER_PHOTO_ID_5441813685712159298" border="0" /></a><br /><span style="font-family:arial;"><span style="font-weight: bold;">The rise in sea level due to thermal expansion will also become exponential</span><br />The increases in global land and sea temperatures are expected to cause huge changes in local climate and weather, and some of the predicted changes are detailed in subsequent posts. For now, we consider only the effects that the global temperature change has on sea level.<br /></span><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://1.bp.blogspot.com/_vRsObFw-TN0/S22hTdCEfeI/AAAAAAAAAOM/thvmgKzFIE8/s1600-h/_Sea+Level+Rise.jpg"><img style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer; width: 286px; height: 194px;" src="http://1.bp.blogspot.com/_vRsObFw-TN0/S22hTdCEfeI/AAAAAAAAAOM/thvmgKzFIE8/s320/_Sea+Level+Rise.jpg" alt="" id="BLOGGER_PHOTO_ID_5435177680888954338" border="0" /></a><br /><span style="font-family:arial;">We can easily estimate the amount of sea level rise due to its temperature increase alone, because this rise comes from the expansion of the volume of water in the ocean. </span><span style="font-family:arial;">This expansion results from the increase in the ocean temperature, which lags the increase in the global surface temperature. Despite a large amount of publicity, there has so far been a relatively small contribution from the melting of ice and glaciers on land. </span><span style="font-family:arial;"> (Note that the melting of floating ice changes surface salinity but does not change the sea level.) </span><span style="font-family:arial;"><br /><br />Therefore, we can use the observed rise in sea level up to now, and combine it with the expected global temperature change, to estimate the expected increase from this effect. The future contribution from melting ice, mostly from the Greenland ice sheet, can be added afterward.<br /><br />Sea level rise does lag the surface temperature increase, of course, because it takes time for heat to transfer through the water column. Because amount of sea level expansion depends linearly on the temperature, however, and because the temperature has an exponential increase, the sea level rise eventually must become exponential with the same time dependence (same rate) as the temperature.* An exponential extrapolation is shown in the figure, matched to the measured rise since 1975 (when the global temperature started its exponential rise).<br /><br />Overall, the sea level rise by 2050 is predicted to be about a half meter (19") from thermal expansion alone. While this may be small compared to the other factors considered to this point, this is not an insignificant rise in terms of wetlands damage and coastline erosion.<br /><br />At this point, we have made the more secure of the predictions that can be made. The remaining sections will summarize some of the more complex issues involving more detailed and less certain climate and weather predictions.<br /><br /><span style="font-weight: bold;">Contributions from the Greenland ice sheet</span><br />The Greenland ice sheet is thought to be the major contributor to sea level rise from melting, now and in the near future. Recent research suggests that it has contributed 25% of the observed rise to date. Complete loss of the Greenland ice sheet will result in a global rise in sea level of 7 meters (22 feet). Current projections, however, are that it may take more than 300 years for the melting to be complete (see the <a href="http://greenphysicist2.blogspot.com/2010/02/tipping-points.html">"tipping point" projections</a> in the next section). The actual melting rate will depend on many factors, including the temperature rise in the future.<br /><br />With all these uncertainties, at this point we just note that if the time for complete melting was as much as 600 years, in the next 40 years we should expect to lose about 7 meters x (40/600) or a half meter. This would suggest that by 2050 we would have a total sea level rise of about a meter (3 feet), half from thermal expansion, half from melting ice. It is quite likely that the contribution from the Greenland melting will be more than this amount; it is unlikely to be less.<br /><br />Next: <a href="http://greenphysicist2.blogspot.com/2010/02/tipping-points.html">Dangerous tipping points ahead</a>.<br /><br /><span style="font-weight: bold;">DETAILS<br /><br /></span></span><span style="font-family:arial;">The observed <a href="http://en.wikipedia.org/wiki/Current_sea_level_rise">rise in sea level</a> (black line) was taken from a Wikipedia review. The predicted exponential rise (red line) is the best fit to the data starting in 1975, when the temperature started its current rapid rise, and is the extrapolation which has the same time dependence as both the global temperature and CO2 levels. The estimate of the amount of sea level rise due to the melting of the Greenland ice sheet is from a (2009) <a href="http://www.sciencedaily.com/releases/2009/06/090612092741.htm">report</a> by S. H. Mernild, <span style="font-style: italic;">et al</span>.<br /><br />* The proof is the same as for the temperature lagging behind the CO2 level when it has an exponential rise, discussed in the last section.<br /><br /></span>David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.com0tag:blogger.com,1999:blog-4923777526767524711.post-55486028031349808742010-02-06T09:00:00.000-08:002010-03-28T17:40:07.850-07:00Global temperatures increase as a result<span style="font-family:arial;"><span style="font-weight: bold;">If the CO2 increases exponentially, so (eventually) must the temperature.</span><br />While estimating the CO2 level is easy, it is the global temperature of our planet that actually drives weather. This is harder to measure because the measured temperatures vary with the time, place, weather and season. It is harder to predict because the average surface temperature depends on many factors, including the reflectivity of the upper atmosphere, and so on.<br /></span><br /><span style="font-family:arial;">There are, however, two factors that make it easier to predict the global temperature going forward from </span><span style="font-family:arial;">the present time. The first is that model calculations indicate </span><span style="font-family:arial;">that </span><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://2.bp.blogspot.com/_vRsObFw-TN0/S48SBxFVGII/AAAAAAAAAUA/lm7CcdmqqOY/s1600-h/_Temp+Rise.jpg"><img style="margin: 0pt 0pt 10px 10px; width: 264px; float: right; height: 241px; cursor: pointer;" id="BLOGGER_PHOTO_ID_5444590296079079554" alt="" src="http://2.bp.blogspot.com/_vRsObFw-TN0/S48SBxFVGII/AAAAAAAAAUA/lm7CcdmqqOY/s320/_Temp+Rise.jpg" border="0" /></a><span style="font-family:arial;">the dominant cause for the rise in global temperature since 1975 has been the increase in CO2 contributed by human activities. The second factor to note is that the global temperature lags th</span><span style="font-family:arial;">e CO2 level because of thermal inertia, largely due to the oceans. However, if the CO2 level rises exponentially, the temperature will also <span style="font-style: italic;">eventually</span> rise exponentially, with the same growth rate, even if it lags the CO2 level.*</span><br /><br /><span style="font-family:arial;">This means that we don't have to determine the growth rate for the temperature from the temperature curve itself. We can just use the same rate as for the CO2 curve. This is fortunate, because the temperature curve is more variable than the CO2 curve and it would not be as reliable to determine a growth rate from it alone. From the temperature curve itself, we only have to determine the <span style="font-style: italic;">time</span> when it started to rise exponentially.<br /><br />The figure shows the measured temperature (black line). This line is the temperature since 1975 smoothed using a moving five-year average. Even so, it is fairly variable. The temperature shown is with reference to the relatively flat average around 1910, the minimum last century. The red line shows an exponential match having the same growth rate as derived for the CO2 level in the previous post. A temperature curve having the same growth rate as the CO2 growth rate is clearly consistent with the temperature data.<br /><br />It can be seen from this match that the rise in global temperature is expected to be about 2.5 degrees Centigrade (4.5 degrees Fahrenheit) by 2050 from the CO2 increase alone. This may not seem like much, until you realize that the <span style="font-style: italic;">warmest</span> our Earth has been in the last 100 million years was only about 5 degrees Centigrade warmer than the present! Further, this much of a rise is enough to get us into the range of some possible catastrophic "tipping points," as discussed later.<br /><br />Next: <a href="http://greenphysicist2.blogspot.com/2010/02/rise-in-sea-level.html">The rise in sea level from this temperature increase</a>.<br /><br /><span style="font-weight: bold;">Details:<br /></span><span style=";font-family:arial;font-size:100%;" >Some of the difficulties in predicting global temperature changes in the sort term may be seen in the news report, <a href="http://www.sciencedaily.com/releases/2008/05/080502113749.htm">Will Global Warming Take a Short Break?</a>, in Science News, May 5, 2008.</span><span style="font-weight: bold;font-family:arial;font-size:100%;" ><br /></span></span><span style="font-family:arial;"><br />The measured temperature variation (black line) is from the 2001 report by the <a href="http://www1.ipcc.ch/ipccreports/assessments-reports.htm">Intergovernmental panel on Climate Change</a> with updated measurements. The red line is the best fit exponential (starting in 1975) that has the same time dependence as the CO2 level.<br /><br /></span><span style="font-family:arial;">*To prove that the temperature rise must eventually become exponential with the same time scale, suppose the temperature rise is proportional to the CO2 level but with a lag time, T. The CO2 level itself is proportional to a constant plus the function exp(t/45), where t is the year. The temperature change will then be proportional to another constant plus a similar exponential term but with its time affected by the lag time, T. That means that the temperature response must contain a term like exp(t-T)/45). Because of the unique properties of the exponential function, the part involving T simply factors out as a constant equal to exp(-T/45), leaving the result that the rise in temperature must </span><span style="font-family:arial;">eventually </span><span style="font-family:arial;">become simply proportional to a constant plus a time-varying part containing the factor exp(t/45), the same factor as the variation in CO2 level. The only necessary assumption is that the overall system can be represented by a linear system in its first or lowest-level approximation, and nearly all systems can.<br /></span>David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.com0tag:blogger.com,1999:blog-4923777526767524711.post-22755337374932094112010-02-06T08:54:00.000-08:002010-03-28T17:33:23.255-07:00Atmospheric carbon dioxide levels double<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://1.bp.blogspot.com/_vRsObFw-TN0/S4X6zXCgl9I/AAAAAAAAASQ/XFD1fy_4KnM/s1600-h/Mauna+Loa+clipped.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 359px; height: 263px;" src="http://1.bp.blogspot.com/_vRsObFw-TN0/S4X6zXCgl9I/AAAAAAAAASQ/XFD1fy_4KnM/s320/Mauna+Loa+clipped.jpg" alt="" id="BLOGGER_PHOTO_ID_5442031485011924946" border="0" /></a><br /><span style="font-family:arial;"><span style="font-weight: bold;">Atmospheric CO2 levels are predicted to become <span style="font-style: italic;">double</span> pre-industrial levels by 2050.</span><br />The CO2 level is easy to predict under "business as usual" for several reasons. First, there have been very accurat</span><span style="font-family:arial;">e, </span><span style="font-family:arial;">d</span><span style="font-family:arial;">irect measurements at Mauna Loa </span><span style="font-family:arial;">since 1958 (above). Measurements of CO2 levels in air bubbles trapped in ice give us less accurate but still useful measurements back through many </span><span style="font-family:arial;">ice age</span><span style="font-family:arial;">s. It is relatively</span><span style="font-family:arial;"> easy to measure and predict the CO2 level because there isn't much random variability and other factors affecting it unlike, say, the surface temperature. The figure below right give</span><span style="font-family:arial;">s the measured and extrapolated CO2 levels from 1900 to 2050.</span><br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://1.bp.blogspot.com/_vRsObFw-TN0/S22fpfJU2rI/AAAAAAAAAOE/LqkaYlFunKo/s1600-h/_CO2+Rise.jpg"><img style="margin: 0pt 0pt 10px 10px; float: right; cursor: pointer; width: 275px; height: 320px;" src="http://1.bp.blogspot.com/_vRsObFw-TN0/S22fpfJU2rI/AAAAAAAAAOE/LqkaYlFunKo/s320/_CO2+Rise.jpg" alt="" id="BLOGGER_PHOTO_ID_5435175860390124210" border="0" /></a><span style="font-family:arial;">The last 1.3 million years our planet has been locked in an ice age cycle, and the CO</span><span style="font-family:arial;">2 level varied consistently between 175 and 275 parts per million (ppm, blue lines in graph). The CO2 level was at about 275 pp</span><span style="font-family:arial;">m in 1800, a typical interglacial maximum. Then the industrial revolution got to work, and human activi</span><span style="font-family:arial;">ty started to increase the levels (black line in graph). The measurements at Mauna Loa (top) clearly show that the recent rise is <span style="font-style: italic;">exponential</span>.<br /><br />An exponential rise is exactly the way your money grows if you put it into a savings account with continuous compounding of your balan</span><span style="font-family:arial;">ce, leaving </span><span style="font-family:arial;">the interest in. It is the way the world economy grows if there is an approximately constant growth rate. So, it shoul</span><span style="font-family:arial;">d be little surprise that the CO2 level has grown exponentially in recent years.</span><br /><span style="font-family:arial;"><br />The theoretical curve</span><span style="font-family:arial;"> (red line)</span><span style="font-family:arial;"> that matches the observations from 1958 to the present turns out to have an annual gr</span><span style="font-family:arial;">owth rat</span><span style="font-family:arial;">e of 2.22%. The figure shows that, if the current rate is maintained, the CO2 levels will reach exactly twice the pre-industrial level in 2050. This is twice the maximum level typically recorded during all of the previou</span><span style="font-family:arial;">s interglacial periods. Clearly, we are leaving the ice age cycle in a big hurry.</span><span style="font-family:arial;"><br /></span><span style="font-family:arial;"><br />Unfortunately, all this is unlikely to change very quickly, because the amount of CO2 added to the atmosphere is equal to the <span style="font-style: italic;">cumulative</span> amount emitted by human activity (<a href="http://www.sciencedaily.com/releases/2009/06/090610154453.htm">Science Daily June 2009</a>). The reason is that CO2 is taken out of the atmosphere by natural processes much more slowly than we are putting it in. Therefore, even if we quit putting in CO2 today, the atmospheric concentration would not drop immediately, but decline slowly over a 100-1000 year time scale.<br /><br />Note that the CO2 level from natural sources and sinks was in <span style="font-style: italic;">equilibrium</span> in 1800, and so was the global system. The system still would be in equilibrium if we hadn't added all the unnatural CO2. This means that the natural CO2 is not the primary <span style="font-style: italic;">cause</span> of global warming even though it still makes up most of the contribution to the atmosphere.<br /><br />Next: <a href="http://greenphysicist2.blogspot.com/2010/02/increase-in-global-temperature.html">The temperature increase by 2050 given these CO2 levels.</a><br /><br /><span style="font-weight: bold;">Details</span>:<br /></span><span style="font-family:arial;">For the graph on the right, the measured CO2 levels (black line) at Mauna Loa are those taken by C. D. Keeling and the <a href="http://www.noaa.gov/">National Oceanic and Atmospheric Administration</a> from 1958 on. Also see <a href="http://greenphysicist1.blogspot.com/search?updated-max=2010-01-25T20%3A08%3A00-08%3A00&max-results=1">section two</a> of the "Climate Change Debate" blog for previous CO2 levels.<br /><br />The red line in the graph is the best fit to the data starting in 1958 and is specifically given by:<br />CO2 level = 280*( 1+exp(0.0222(year-2052)) ). This formula gives the projected CO2 level in parts per million (ppm) for any year from 1958 on, assuming the growth rate is constant at 2.22%.<br /></span>David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.com0tag:blogger.com,1999:blog-4923777526767524711.post-20769078694139599052010-02-03T05:17:00.000-08:002010-04-02T08:47:47.272-07:00Introduction: Forecast for Earth if we continue as global warming skeptics propose<span style="font-family:arial;"><span>In this series, we explore exactly what we can expect just 40 years from now in terms of weather, climate, and related effects on our lives. We assume that we ignore the warnings from experts</span></span><span style="font-family:arial;"><span> and simply continue "business as usual"-- as the climate skeptics propose. As discussed below, we can't depend on the rosy predictions of the International Panel on Climate Change (IPCC).* So, we work the forecast out ourselves, in a straightforward manner.</span><span style="font-weight: bold;"><br /><br /></span></span><span style="font-family:arial;"><span style="font-weight: bold;">The results are the <span style="font-style: italic;">Forecast for Earth in 2050</span>:<br /><br /></span>The<span style="font-weight: bold;"> </span></span><span style="font-family:arial;"><a href="http://greenphysicist2.blogspot.com/2010/02/atmospheric-carbon-dioxide-levels.html">carbon dioxide level</a></span><span style="font-family:arial;"><span style="font-weight: bold;"> </span>in our atmosphere will be <span style="font-weight: bold; font-style: italic;">twice</span> the pre-industrial level.<br /><br />The <a href="http://greenphysicist2.blogspot.com/2010/02/increase-in-global-temperature.html">global temperature will be as high as three degrees</a> Centigrade (5 degrees F) warmer than its baseline level last century.<br /><br />The rapid rise in temperature will cause instabilities in the world's weather system which result in increases of <span style="font-weight: bold;">extreme weather</span></span><span style="font-family:arial;"><span style="font-weight: bold;"> of all kinds</span> -- record storms, rains, snows, droughts and flooding.<br /><br /><span style="font-weight: bold;">A</span><span style="font-weight: bold;">griculture</span> around the world will suffer. </span><span style="font-family:arial;">Limited resources and starving populations will lead to increases in conflicts and wars.<br /><br />There will be about a meter rise in <a href="http://greenphysicist2.blogspot.com/2010/02/rise-in-sea-level.html">sea level</a>.<br /><br />The one meter rise, combined with extreme storm surges, will cause massive damage to <a href="http://greenphysicist1.blogspot.com/search?updated-max=2010-01-25T17%3A19%3A00-08%3A00&max-results=1">coastal areas</a> around the world.<br /><br />The temperature rise will bring the Earth close to several <a href="http://greenphysicist2.blogspot.com/2010/02/tipping-points.html">major "tipping points</a>" -- where a rise in global temperature is <span style="font-style: italic;">amplified</span> by a major transition.<br /><br />The first tipping point transition, already starting, involves <a href="http://greenphysicist2.blogspot.com/2010/02/permafrost-melts-earth-heats-even-more.html">melting of the Arctic permafrost</a> --causing the potent greenhouse gas methane to be released in massive quantities.<br /><br />These results are summarized in our <a href="http://greenphysicist2.blogspot.com/2010/02/our-earth-in-2050.html">Final Forecast for </a><a href="http://greenphysicist2.blogspot.com/2010/02/our-earth-in-2050.html">our Earth in 2050</a>.<br /><!--INFOLINKS_ON--><br /></span><span style="font-family:arial;"><span style="font-weight: bold;">Why did we have to work the forecast out ourselves? Because the IPCC is <span style="font-style: italic;">not</span> telling us the whole truth.<br /></span>At a recent meeting of the American Association for the Advancement of Science (San Diego, 2010), several prominent scientists complained about serious problems in reports from the Intergovernmental Panel on Climate Change (<span class="blsp-spelling-error" id="SPELLING_ERROR_1"><span class="blsp-spelling-error" id="SPELLING_ERROR_1">IPCC</span></span>). The problem with IPCC global warming forecasts, they said, is that politicians in most home countries are conservative and are putting pressure on their members.<br /><br />Worse, organizations and individuals covertly supported by special interests have been attacking everything that any legitimate scientist says, <span class="blsp-spelling-corrected" id="SPELLING_ERROR_2">viciously</span> and persistently, blasting them with outright lies and deliberate misrepresentations.**<br /></span><br /><span style="font-family:arial;">In defense, the IPCC published reports have been prepared very cautiously, understating what scientists really believe to be the facts. <span style="font-style: italic;"><span>The situation is actually worse than their reports would have us believe.</span> </span><br /><br />How can we find out what the truth really is? Well, we can just take the observed numbers, numbers that are well-established. Then we can make simple, straightforward extrapolations </span><span style="font-family:arial;">of the trends observed up to now, assuming <span style="font-style: italic; font-weight: bold;">only</span> that things go on as they have been going.<br /><br />We do exactly what the climate change skeptics <span style="font-style: italic;">want</span> us to do, assume that everyone continues "business as usual." Then, we see what conditions will be like at mid-century -- using existing numbers and straight extrapolation.<br /></span><br /><span style="font-family:arial;">Next post: </span><a style="font-family: arial;" href="http://greenphysicist2.blogspot.com/2010/02/atmospheric-carbon-dioxide-levels.html">The carbon dioxide level doubles by 2050</a><span style="font-family:arial;">.</span><br /><br /><span style="font-family:arial;"><span style="font-weight: bold;">DETAILS<br /></span></span><span style=";font-family:arial;font-size:100%;" ><span>* Since this was written<span style="font-weight: bold;">,</span> Professor Charles Green at Cornell (with other authors) published a peer-reviewed paper that concludes that the IPCC in its 2007 report "<span style="font-style: italic;">underestimates</span> the potential dangerous effects that man-made climate change will have on society;" as reported in <a href="http://www.sciencedaily.com/releases/2010/03/100322232229.htm">Science Daily March 23, 2010</a>. (Italics added.)<br /><br /></span></span><span style="font-family:arial;">** Did you know that some of these front organizations openly offer to pay $10,000 to any scientist who comes aboard their little boat, and lies and distorts facts so that people become "skeptical" of the truth? Well, they do. They'll even publish your paranoid lying little book for you. All you have to do is cross over to the dark side and join the tobacco, coal and oil industry-paid "scientists." It is awfully tempting. To us at least. </span><span style="font-family:arial;"><br /></span><br /><span style="font-family:arial;">The map at top right shows the average temperature increases over the last decade relative to 1951-1980 local means. The map is from NASA. Details were reported in a Science Daily <a href="http://www.sciencedaily.com/releases/2010/01/100121170717.htm">article</a> Jan. 22, 2010.</span><br /><span style=";font-family:arial;font-size:100%;" ><span><span style="font-weight: bold;"><br /></span></span><span style="font-weight: bold;">COMMENTS</span> made by readers, and replies from this site, follow directly after the main text of each post, in order of date posted</span><span style="font-size:100%;"><span style="font-family:arial;">. If you wish to contribute a comment, click on the comment link at the very bottom of the most appropriate page.</span></span><span style=";font-family:arial;font-size:100%;" ><br /><br /><span style="font-weight: bold;">Please</span>, if you want to convince others of your point of view, give whatever background you can for what you say. If you think the Earth is warmer because the sun's output has increased lately, please let us know where you read or heard this idea, and any evidence that was given for it. I myself have no idea at all where people are getting some of the ideas stated, and I would really love to find out more about the ideas and what their sources are.</span><br /><span style="font-weight: bold;font-family:arial;" ><br />COMMENTS</span><br /><br /><span style="font-weight: bold;font-family:arial;" >March 14, 2010. Anonymous said...</span><br /><span style="font-family:arial;">Nonsense..IPCC actually has been proven to overstate just about everything.</span><br /><br /><span style="font-weight: bold;font-family:arial;" >March 21, 2010. David Mills replied...</span><br /><span style="font-family:arial;">My sources were climate scientists attending the AAAS meeting in San Diego this year. What were yours? The newspapers, perhaps?</span><br /><br /><span style="font-family:arial;">Any report collecting and condensing data from many sources is going to be trying to balance all of the inputs, and whatever they say someone will think that they have overstated, someone else will think they understated. The problem with the IPCC reports in particular is that the skeptics (and those in the pay of the special interests) are pouring over them, trying to find every small exaggeration or mistake. When they find a mistake that overstates, they announce it loudly.<br /><br />When they find something that understates, they say nothing. I mean, who would care about that? Do you ever imagine a skeptic calling into a newspaper with the news that the IPCC has <span style="font-style: italic;">underestimated</span> the amount of global warming somewhere?</span> <span style="font-family:arial;">And the newspaper printing it on the front page?</span><br /><br /><span style="font-family:arial;">So, all you ever hear about are the exaggerations or overstatements. To find the real story you have to talk with the scientists who are responsible for the input to the reports, to see what they think of the final reports when they come out of committee. And they think the committees are biasing their reports conservatively to avoid controversy.</span> <span style="font-family:arial;"> (Not that this works, obviously.)</span><br /><br /><span style="font-family:arial;">Added later: Also see the recent peer-reviewed paper by Prof. Green, et al., referenced in Details above.</span> <span style="font-family:arial;"> We'll bet it wasn't carried on the front page of your newspaper, or maybe even anywhere in your newspaper.</span><br /><!--INFOLINKS_OFF-->David Mills, Ph.D., M.A.http://www.blogger.com/profile/13115000746728769229noreply@blogger.com1