Needless to say, the past thirteen years of zero change has cut downthe modeling projections. What is not mentioned here is that thesensitivity to CO2 forcing is hugely cut if not even zeroed out. Quite simply, if any part of the rise in the nineties was due to CO2,where did it go in the past thirteen years? You cannot claim onewithout addressing the other. It be comes way easier to outrightdismiss CO2 forcing.
It is within human capacity to change the climate. It is just notlikely to be by burning a lot of coal. Nature manages CO2 way toowell. More wisely we need to reforest the Sahara and the MiddleEast. This would restore Bronze Age conditions which would be a goodthing and allow global populations to double at least.
In the meantime we do have a cyclic warming trend that is post Littleice Age and no proper explanation for that event. It is myconjecture that it is driven by a thousand year long cycle of thesouthern circupolar current that manages the injection of cold waterinto the Atlantic Basin.
Global warming lessextreme than feared?
by Bard Amundsenand Else Lie
Oslo, Norway (SPX)Feb 01, 2013
http://www.terradaily.com/reports/Global_warming_less_extreme_than_feared_999.html
Policymakers areattempting to contain global warming at less than 2C. New estimatesfrom a Norwegian project on climate calculations indicate this targetmay be more attainable than many experts have feared.
Internationallyrenowned climate researcher Caroline Leck of Stockholm University hasevaluated the Norwegian project and is enthusiastic.
"These resultsare truly sensational," says Dr Leck. "If confirmed byother studies, this could have far-reaching impacts on efforts toachieve the political targets for climate."
Temperature rise islevelling off
After Earth'smean surface temperature climbed sharply through the 1990s, theincrease has levelled off nearly completely at its 2000 level.Ocean warming also appears to have stabilised somewhat, despite thefact that CO2 emissions and other anthropogenic factors thought tocontribute to global warming are still on the rise.
It is the focus onthis post-2000 trend that sets the Norwegian researchers'calculations on global warming apart.
Sensitive togreenhouse gases
Climatesensitivity is a measure of how much the global mean temperature isexpected to rise if we continue increasing our emissions ofgreenhouse gases into the atmosphere.
CO2 is the primarygreenhouse gas emitted by human activity. A simple way to measureclimate sensitivity is to calculate how much the mean air temperaturewill rise if we were to double the level of overall CO2 emissionscompared to the world's pre-industrialised level around the year1750.
If we continue to emitgreenhouse gases at our current rate, we risk doubling thatatmospheric CO2 level in roughly 2050.
Mutual influences
A number offactors affect the formation of climate development. The complexityof the climate system is further compounded by a phenomenon known asfeedback mechanisms, i.e. how factors such as clouds, evaporation,snow and ice mutually affect one another.
Uncertainties aboutthe overall results of feedback mechanisms make it very difficult topredict just how much of the rise in Earth's mean surface temperatureis due to manmade emissions. According to the Intergovernmental Panelon Climate Change (IPCC) the climate sensitivity to doubledatmospheric CO2 levels is probably between 2C and 4.5C, with the mostprobable being 3C of warming.
In the Norwegianproject, however, researchers have arrived at an estimate of 1.9C asthe most likely level of warming.
Manmade climateforcing
"In ourproject we have worked on finding out the overall effect of all knownfeedback mechanisms," says project manager Terje Berntsen, whois a professor at the University of Oslo's Department of Geosciencesand a senior research fellow at the Center for International Climateand Environmental Research - Oslo (CICERO). The project has receivedfunding from the Research Council of Norway's Large-scale Programmeon Climate Change and its Impacts in Norway (NORKLIMA).
"We used a methodthat enables us to view the entire earth as one giant 'laboratory'where humankind has been conducting a collective experiment throughour emissions of greenhouse gases and particulates, deforestation,and other activities that affect climate."
For their analysis,Professor Berntsen and his colleagues entered all the factorscontributing to human-induced climate forcings since 1750 into theirmodel. In addition, they entered fluctuations in climate caused bynatural factors such as volcanic eruptions and solar activity. Theyalso entered measurements of temperatures taken in the air, onground, and in the oceans.
The researchers used asingle climate model that repeated calculations millions of times inorder to form a basis for statistical analysis. Highly advancedcalculations based on Bayesian statistics were carried out bystatisticians at the Norwegian Computing Center.
2000 figures make thedifference
When theresearchers at CICERO and the Norwegian Computing Center appliedtheir model and statistics to analyse temperature readings from theair and ocean for the period ending in 2000, they found that climatesensitivity to a doubling of atmospheric CO2 concentration will mostlikely be 3.7C, which is somewhat higher than the IPCC prognosis.
But the researcherswere surprised when they entered temperatures and other data from thedecade 2000-2010 into the model; climate sensitivity was greatlyreduced to a "mere" 1.9C.
Professor Berntsensays this temperature increase will first be upon us only after wereach the doubled level of CO2 concentration (compared to 1750) andmaintain that level for an extended time, because the oceans delaythe effect by several decades.
Natural changes also amajor factor
The figure of 1.9C asa prediction of global warming from a doubling of atmospheric CO2concentration is an average. When researchers instead calculate aprobability interval of what will occur, including observations anddata up to 2010, they determine with 90% probability that globalwarming from a doubling of CO2 concentration would lie between 1.2Cand 2.9C.
This maximum of 2.9Cglobal warming is substantially lower than many previous calculationshave estimated. Thus, when the researchers factor in the observationsof temperature trends from 2000 to 2010, they significantly reducethe probability of our experiencing the most dramatic climate changeforecast up to now.
Professor Berntsenexplains the changed predictions:
"The Earth's meantemperature rose sharply during the 1990s. This may have caused us tooverestimate climate sensitivity.
"We are mostlikely witnessing natural fluctuations in the climate system -changes that can occur over several decades - and which are coming ontop of a long-term warming. The natural changes resulted in a rapidglobal temperature rise in the 1990s, whereas the natural variationsbetween 2000 and 2010 may have resulted in the levelling off we areobserving now."
Climate issues must bedealt with
Terje Berntsenemphasises that his project's findings must not be construed as anexcuse for complacency in addressing human-induced global warming.The results do indicate, however, that it may be more within ourreach to achieve global climate targets than previously thought.
Regardless, the fightcannot be won without implementing substantial climate measureswithin the next few years.
Sulphate particulates
The project'sresearchers may have shed new light on another factor: the effects ofsulphur-containing atmospheric particulates.
Burning coal is themain way that humans continue to add to the vast amounts of tinysulphate particulates in the atmosphere. These particulates can actas condensation nuclei for cloud formation, cooling the climateindirectly by causing more cloud cover, scientists believe. Accordingto this reasoning, if Europe, the US and potentially China reducetheir particulate emissions in the coming years as planned, it shouldactually contribute to more global warming.
But the findings ofthe Norwegian project indicate that particulate emissions probablyhave less of an impact on climate through indirect cooling effectsthan previously thought.
So the good news isthat even if we do manage to cut emissions of sulphate particulatesin the coming years, global warming will probably be less extremethan feared.
About the project
Geophysicists atthe research institute CICERO collaborated with statisticians at theNorwegian Computing Center on a novel approach to global climatecalculations in the project "Constraining total feedback in theclimate system by observations and models". The project receivedfunding from the Research Council of Norway's NORKLIMA programme.
The researcherssucceeded in reducing uncertainty around the climatic effects offeedback mechanisms, and their findings indicate a lowered estimateof probable global temperature increase as a result of human-inducedemissions of greenhouse gases.
The projectresearchers were able to carry out their calculations thanks to thefree use of the high-performance computing facility in Oslo under theNorwegian Metacenter for Computational Science (Notur). The researchproject is a prime example of how collaboration across subject fieldscan generate surprising new findings.
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