RADIATIVE FORCING: This graph, for the first time, sums the various factors affecting how much heat gets trapped by Earth. [Click on image to enlarge.]
Image: IPCC
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The Best Science Writing Online 2012
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The debate over whether Earth's climate is changing and if humanity is responsible for that change closed in Paris on February 2. The Intergovernmental Panel on Climate Change (IPCC) released its summary for policymakers—a summation of the salient science in its much longer report due in May—in which it said that climate change is "unequivocal" and estimated the chances of humans being behind it at 90 percent, or "very likely."
New observations and new models contributed to this certainty, ranging from Antarctic ice cores to improved understanding of solar fluxes. Carbon dioxide (CO2) levels in the atmosphere—379 parts per million (ppm) in 2005—have reached levels not seen in the last 650,000 years, which have varied between 180 ppm and 300 ppm. The burning of fossil fuels is the main CO2 contributor to the atmosphere, followed by clearing land for agriculture.
A better understanding of the constituents of the atmosphere, as well as various natural processes on Earth and on the sun, has allowed scientists to sum the various forcings—factors that can increase or decrease the retention of heat on the planet—for the first time. [see graph above). While the sun is contributing an extra 0.12 W/m2 (watts per meter2)—and aerosols and cloud cover combine to cool Earth by 1.2 W/m2—CO2, methane and nitrous oxide, among other greenhouse gases, are warming the globe by 2.3 W/m2.
Such radiative forcing is easy to see in the recent climate record: 11 of the past dozen years "rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850)," the scientists note in the summary. The Arctic has led the way, its temperatures increasing at twice the global average, but worldwide days of extreme temperatures have become far more frequent over the past 50 years on every continent except Antarctica [see graph below].
The ocean absorbs most of the extra heat trapped by greenhouse gases—more than 80 percent—with temperatures rising up to 3,000 meters below the surface. Such warming provides stronger fuel for the furious storms called tropical cyclones that form over open waters (known in the Atlantic as hurricanes). It also causes the water itself to expand—so-called thermal expansion—contributing to a sea level rise of 0.17 meter (nearly seven inches) in the 20th century. And the rate of that expansion appears to be accelerating, averaging 3.1 millimeters (0.1 inch) per year between 1993 and 2003.
But, as the world's glaciers recede, melting ice is also contributing to the rise in sea levels. In fact, the last time the Arctic and Antarctic were three degrees Celsius (5.4 degrees Fahrenheit) warmer—roughly 125,000 years ago—sea levels rose by as much as six meters (20 feet) thanks to the melting of the Greenland ice sheet.
Such warming—three degrees C (5.4 degrees F)—is the scientists' best estimate of how much average temperatures would rise if greenhouse gas concentrations were allowed to double from preindustrial levels. Warming of 0.6 degree C (one degree F) is already guaranteed for this century, due to the CO2in place, which will remain there for centuries. That will have a host of impacts, from more severe droughts to more and stronger floods as a result of downpours.
A study of such impacts is now in the works by an assemblage of scientists under the auspices of the IPCC. That report is scheduled to be released in April, followed in May by another group's report on options for adaptation and mitigation. By November a complete synthesis of all three reports—totaling more than 1,600 pages—will be available. But the basic message is already clear: climate change is occurring and efforts must be made to minimize its dangerous consequences.
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11 Comments
Add CommentThe IPCC is not a scientific organization, their political activist document, did not take into account changes in solar output, or changes in the magnetosphere. Further, they attributed all those factors to mankind. Scientific fraud.
Reply | Report Abuse | Link to thisAbsolute Hogwash. The IPCC is as corrupt an organization as you will find on the planet. Their politically influenced conclusions on man causing global warming are completely false and people know it. The real problem is the lasting and permanent damage they have done to the reputation of the scientific community. Essentially most environmental scientist are now viewed as nothing more than common Whores who will do and say anything to get grant money. If the US Gvt announced tomorrow that Billions of dollars in grants are now available to study Global Cooling, you can bet that we would be told about the coming new Ice Age. Just like in the late 1970s. If any of you were true historians of scientific history you know that in all cases, the scientific consensus on any subject ,was proven wrong by small groups of real scientist that dug out the truth. The real scientists today are the ones who stand up to the Whores and say man made global warming is a HOAX!
Reply | Report Abuse | Link to thisStill pseudo-science "bovine fecal matter" . Just the same ol' political spew!
Reply | Report Abuse | Link to thisIPCC- (Ignorant People Can't Calculate)
I wonder how many went along with this just to protect their careers? The "Religion of Big Science" does not tolerate independent thinking.
Reply | Report Abuse | Link to thisThe solution is :
Reply | Report Abuse | Link to thisHuman Excrement + Nuclear Waste = Hydrogen
dennisbaker2003@hotmail.com
MONEY=ENERGY=POLLUTION
Reply | Report Abuse | Link to thisreduce the global monetary supply and this will regulate the problem
Also a 100% Carbon tax where there is only one tax at source, and removal of all other forms of taxes together with a rebate system for the promotion of sustainable population, social and environmental harmony.
There must be 100% linkage between the fiscal and climate debate,not separate and disjointed as at present.
Interesting... right wing trolls still on patrol. With their same "clever tactic" of besmearing legitimate scientist, how quaint.
Reply | Report Abuse | Link to thisFunny thing is, they seem not to know that people are aware that it was Southern Power Company which created the faux scientific group known as "The Climate Committee" - whose only task was to attend climate conferences with the idea of arguing against pollution regulations - which Southern Power Company at that time had already violated over 200 times in a two year span.
Now who are the money grubbing shills, eh, right wingnut trolls? :-)
"right wing trolls" ... "bovine fecal matter"....
Reply | Report Abuse | Link to thisStatements like these are beneath contempt
If anyone wants to actually stick to the facts and argue positions based on the science, that would be great.
But, it looks like all anyone on either "side" of this issue wants to do is call the other side names.
How about a real discussion about the science?
Thanks you "Theroofbroker". I can always tell when I am being pushed into a scam when the one with the weaker argument starts with name calling and ignores credible questions. Its obvious to a great many people that the "human cause" climate studies are fraudulent and the IPCC is a political activist group. I am not a right winger or left winger I just want the truth and we haven't heard it yet.
Reply | Report Abuse | Link to thisFrom the latest science of the mind/brain discoveries it's clear we human beings don't use our cerebral cortex for any thought that could be done more efficiently with another part of our brain. When a partisan brain is evaluating a position the brain doesn't even turn on the cerebral cortex but instead uses other pathways like the food response pathway to simulate thought. In this case if it looks like someone vomitted all over an idea, then at least from the brain areas involved, that's exactly what they did. Your pickle preference determines your politics, your climate science, your abortion views and your tax and debt policy beliefs. An energy optimizing brain has no actual need to get these views right, it's merely satisfying your dopamine hit for feeling righteous and saving prescious glucose and oxygen resources for real rather than existential threats to our survival. Getting climate science right requires rigorous, deliberate, skeptical, creative inquiry. When people are presenting alternate explanatory theories and supporting evidence then a real discussion with active cerebral cortexes is happening. When all that's going on is attacking the others motives or position then no rational brains are involved.
Reply | Report Abuse | Link to thisEditors: the link to the readable graph is broken.
Reply | Report Abuse | Link to thisCommenters: it would seem to me that you'd have wanted to at least see the graph before judging the article.