C02 at Mauna Loa, Hawaii
Global Average Temperature Courtesy of NASANow down to global warming. A few comments on this blog and a HUGE number of letters to the letters of local newspapers and online comments have asked the following question:
You say CO2 causes global warming. Well, CO2 has been going up the past ten years and the earth hasn't warmed during that period! Doesn't that mean that the global warming "theory" is wrong? What gives? Some of the more passionate comments go further, talking about liberal conspiracies, Al Gore, hoaxes, and places I don't want to go right now. But reasonable people ask this question...and there is a reasonable (although complex) answer.
Lets start with the data, shown above. Co2 and other greenhouse gases are going up steadily and have been as long as we have had direct measurements. We understand this. Mankind is the culprit. No responsible scientist doubts this. The other figure shows global temperature--generally going up, but there are are some periods of slight cooling or steady temperatures. Since the late 1990s, temperatures, albeit high, have shown little trend. This is what has some people concerned. But its worst that that they say. Some global warming computer simulations show warming during that period (see figure). Now we are really in trouble. Some of the models are failing too! Fox News was right! Mayor Nickels was wrong!
Not so fast. It turns out that global warming IS a real issue and the above doesn't prove anything really. The truth is that we have a signal to noise issue. The signal is the warming due to greenhouse gases. From our computer models and theory, we know that human-induced warming was quite small until recently (last few decades). And our models and theory indicate it will rapidly increase during this century. But there is also what I will call "noise"--natural variability in the atmosphere that obscures the global warming signal.
The atmosphere has all kinds of natural cyclic and non-cyclic phenomena that causes temperatures to vary even without any global warming. You know some of the them...El Nino and La Nina. Or the Pacific Decadal Oscillation. Or the Arctic Oscillation. There are too many to list. And the essential character of the atmosphere can produce variations on time scales of years to decades. Call this noise. And such noise obscures the global warming signal. When global warming is relatively weak (like now) the noise can even stop the warming or even cause temporary cooling. But it won't last. Eventually the noise will change sign (to warming) or the global warming signal will inevitably strengthen as greenhouse gases increases. Global warming will become apparent and more and more significant. There are also some other minor players to note...like solar variability (e.g, the sunspot cycle), which can produce slight reductions in solar radiation for a few years (like the past few).
During the past several years, global warming has undoubtedly lessened due to a combination of natural variability and a slight weakening of solar radiation, but you can bet that this will turn around very soon. (e.g., El Nino's bring warming and we are now switching into one). The fact that warming has paused for a few years really doesn't mean anything and doesn't disprove anything.
Finally, if you have my book there is a chapter on climate change, global warming, and its local implications.
I have a quote that I carry around in my wallet: "Many argue; few converse" by Louisa May Alcott. Thanks for choosing to educate and share about our current understanding of climate change / global warming, and not to vilify. I feel strongly about our current global situation, and yet sense that nurturing an us/them mentality isn't the way towards health (climatic or otherwise!).
ReplyDeleteBy the way - great clouds the last few days!
Some researches say the effects of global warming are reduced by “solar dimming” due to particulate matter in the atmosphere. (Also caused by rapid industrialization) Solar dimming is a problem because it reduces the amount of sunlight in areas of the world used for agriculture, but if we reduce the particulates, the earth will heat up more rapidly. If this is true, why aren’t we hearing much about it?
ReplyDeleteSome researches say the effects of global warming are reduced by “solar dimming” due to particulate matter in the atmosphere. (Also caused by rapid industrialization) Solar dimming is a problem because it reduces the amount of sunlight in areas of the world used for agriculture, but if we reduce the particulates, the earth will heat up more rapidly. If this is true, why aren’t we hearing much about it?
ReplyDeleteCliff Mass: Please comment on the role of water vapor in amplifying the warming initiated by CO2. Are changes in land use important?
ReplyDeleteThank you, Professor Mass, for discussing and explaining clearly some of the scientific issues of Global Climate Disruption.
ReplyDeleteI'd commented before that "The World Health Organization estimates that global warming is already responsible for 150,000 deaths and 5 million illnesses each year."*
I mention it again to remind us all of the impact of our actions around the world -- as most of the deaths, so far, are in poor countries.
I'd also mentioned a Real Change article called "Four Hiroshimas" which deals with why we are sometimes hated in the world. (It was delayed to the current issue.)
Thank you again for being willing to deal with -- and explain -- the issues of Global Warming / Change, since we in the US have significant responsibility for CO2 production.
*Read Dr. Evan Kanter's talk at the EPA event for supporting evidence: http://www.psr.org/congress-administration/greenhouse-gas-endangerment.html
How about methane in the taiga or hydrate deposits offshore?
ReplyDeleteCliff, do you believe global warming is such a severe issue that we should spend billions now to mitigate it, instead of spending those billions on other issues like malaria prevention?
ReplyDeletenice to hear some intelligent discussion on the topic instead of the usual "it's cold where i am therefore global warming is a hippie/liberal smackjob" (it snowed last year!!). Probably decedents of the same people who thought the earth was flat 500 years ago. Now Cirrus Driver asks a really really good question.. is it really worth it to fight global warming or do we just let it go??
ReplyDeleteCirrus Driver
ReplyDeleteHave you ever thought that our influence on the climate might effect the spread of malaria..
Josh said to Cirrus Driver
ReplyDelete"Have you ever thought that our influence on the climate might effect the spread of malaria.."
The sentences following my earlier quote from the W.H.O. are these:
"These come in the form of malnutrition, diarrhea, and mosquito-borne diseases like malaria and dengue fever. So far the impact has occurred predominantly in poor countries, but the health effects are also evident here in the developed world and will be increasingly felt if we do not take action."
The intensity of my feeling about this comes from our focus on how Climate Change may affect *our* weather ... and so little on how our activities may affect others.
hey Cliff, ...
ReplyDeleteYou should see - (as in "take a look at" - perhaps better said) .. what's being said, regarding this, your most recent blog entry, GW-related, .. over at "Western USA" Wx Forums". (Fairly typical.)
Here's the direct url, to main topic - in question, and initial post to it. .. (if it works). http://westernusawx.com/forums/index.php?showtopic=26944 (If not, I guess you'll - or anyone else reading this, will .. have to "google" the main forum site. - The topic is under main Western Wx discussion.)
Of course I love and also respect, "all" of the various, members, contributors to, and guests visiting the site and board.
richard583
Richard,
ReplyDeleteI took a look...some of these folks are a little "emotional." I don't know what it is about global warming...it brings out people with some issues.....cliff mass
Thanks for shedding some clear scientific light on the climate change issue. It is a very difficult scientific topic and has been politicized. We need calmer voices like yours because the best science is not conducted in that atmosphere.
ReplyDeleteI must say however that I have always have disliked the way the CO2 data at Mauna Loa is presented in the graph you use. The problem is that the y axis is truncated and does not show the zero point. If re-plotted to show the zero point it will still show the increase and indicate how we are approaching the "doubling" scenario that many models simulate. That perspective is needed.
Finally I though you would enjoy these pictures of Morning Glory clouds in Australia. http://antwrp.gsfc.nasa.gov/apod/ap090824.html
Thank you for letting data lead the story, and for explaining how the data works overall.
ReplyDeleteI have been pointing out to folks tha global warming is a long-term trend with more than just warming temperature trends. I tell them to think of watching a pot of water come from cold to a boil. Long before it finally breaks to boiling you can observe the steady increase of turbulence as warmer water rises.
I then point out that while temps warm over a long period of time we will also tend to see more "weather" as the increased energy drives the atmosphere towards more "churn".
Is that a valid analogy? Is there anything that could make it more accurate while keeping it accessible?
I also point out that the impacts of global warming/climate change are being documented across a far wider range of subjects than average temps. We have creeping spring and fall patterns, moving warm seasons closer to the poles (start earlier, end later), changing fauna distributions that correlate to temp trends, the obvious long-term recession of glacial flows and the disintigration of Greenland's ice sheets, and so on. Evidence from the fields of biology, agriculture, and other sciences stand behind the long-term warming trend. How can we discount such numerous observations from so many areas?
According to Schmidt and Wolfe (2009), 19 of the warmest years on record have occurred in the past 25 years. The warmest years globally have been 1998 and 2005 with the years 2002, 2007, and 2003 close behind. The warmest decade has been the last ten years and the warming has been widespread globally. Further signs of this warming trend can be seen in the Northern Hemisphere Sea Ice Extent from the National Snow and Ice Data Center at http://nsidc.org/data/seaice_index/images/n_plot_hires.png. As the graph in the hyperlink shows, sea ice extent has been dramatically reduced since 1979. Ice thickness has also dramatically decreased.
ReplyDeleteSo why do some climate contrarians claim that there is global cooling in the face of this data? It boils down to "cherry-picking" data to intentionally misinform the public. Figure 25c (Hausfather, 2008) athttp://www2.sunysuffolk.edu/mandias/global_warming/images/10_years_no_cooling.jpg shows global surface and lower troposphere monthly mean anomalies relative to the 1979-1998 mean temperature. The data is from GISS, HadCRU, RSS, and UAH ranging from January 1979 to February 2008. GISS, HadCRU, RSS, and UAH represent the four organizations that publish online the global average temperature estimates.
When one considers monthly mean temperature anomalies from 1998 to 2008 it might “appear” that there is a flat line or global cooling. Keep in mind two important points:
1998 was a strong El Niño year which caused a very warm signal and 2008 had a strong La Niña which caused a very cool signal.
These are ANOMALIES not actual temperatures. These are values compared to 1979 to 1998 means.
One will notice that MOST of the time between 1998 and 2008 the anomalies are POSITIVE which means most of the time the planet was warmer than 1979-1998 means. GISS and HadCRU both show a warming trend of 0.16 oC per decade from 1979 to February 2008. RSS shows a warming trend of 0.18 oC per decade over the same period, while UAH shows a warming trend of 0.14 oC.
One cannot cherry pick the endpoints to make the graph that they “want to see.” The global warming critics choose 1998-2008 because they know that using these endpoints makes the trend look flat or negative! If one were to choose 1985 and 1998 as endpoints the global warming would look like it was “going through the roof!”
Here is a more technical analysis of why global temperatures have not "cooled since 1998" nor "cooled since 2001" as some global warming critics claim: Embarrassing Questions from the Open Mind Blog found at http://tamino.wordpress.com/2009/06/26/embarrassing-questions/
Feel free to peruse my Global Warming: Man or Myth? site at http://www2.sunysuffolk.edu/mandias/global_warming/
Thanks Dr. Mass for your objective information on Global Climate change. The data that I am familiar with shows flat-lining from 1998-2007 and slight cooling over the last two years (probably due largely to a sunspot decrease during this period).
ReplyDeleteI too believe that ÇO2 is not the best indicator of global temperature change (H20 vapor and methane are more directly correlated to temperature change). Models of the atmosphere are very complex and its GIGO. One thing I know - is that in this fragile economy driven by capitalism still, that Cap and Trade (Tax) would create far more harm than benefit. Keep us in the loop on new information on this topic.
Thanks Dr. Mass for your objective information on Global Climate change. The data that I am familiar with shows flat-lining from 1998-2007 and slight cooling over the last two years (probably due largely to a sunspot decrease during this period).
ReplyDeleteI too believe that ÇO2 is not the best indicator of global temperature change (H20 vapor and methane are more directly correlated to temperature change). Models of the atmosphere are very complex and its GIGO. One thing I know - is that in this fragile economy driven by capitalism still, that Cap and Trade (Tax) would create far more harm than benefit. Keep us in the loop on new information on this topic.
Official government measurements show that the world’s temperature has cooled a bit since reaching its most recent peak in 1998.
ReplyDeleteThat’s given global warming skeptics new ammunition to attack the prevailing theory of climate change. The skeptics argue that the current stretch of slightly cooler temperatures means that costly measures to limit carbon dioxide emissions are ill-founded and unnecessary.
Proposals to combat global warming are “crazy” and will “destroy more than a million good American jobs and increase the average family’s annual energy bill by at least $1,500 a year,” the Heartland Institute, a conservative research organization based in Chicago, declared in full-page newspaper ads earlier this summer. “High levels of carbon dioxide actually benefit wildlife and human health,” the ads asserted.