Q & A: Global Warming

There was an interesting piece that appeared in the October 12 edition of the Seattle Times, “Q&A: Global warming — a world of evidence”. This follows up on a previous article by journalist Sandi Doughton in the October 9 issue of the Times, “The Truth About Global Warming”.

In the Q&A, a group of University of Washington scientists, including atmospheric scientist and climate researcher J. Mike Wallace, weigh in with answers to questions fielded from the paper’s readers. Many of the questions, such as “Isn’t it true that scientists in the 1970s said the earth was cooling?” are quite similar to those we’ve addressed here at RealClimate (see “The Global Cooling Myth”).

Wallace’s perspectives are particularly interesting because he is both a highly respected climate researcher (and National Academy of Sciences member) and, like a number of other long-time researchers in the field, was once a “skeptic” (in the best sense of the word) regarding the evidence for anthropogenic climate change. However, like many other such researchers, he has become convinced by the compelling weight of evidence indicating human influence on climate that has unfolded over the past decade, remarking that “with each passing year the evidence has gotten stronger — and is getting stronger still.

120 comments on this post.
  1. Blair Dowden:

    Re #93 – A look at the claim that solar activity is the highest in 8,000 years, from the Max Planck Society, shows a graph with a long period with little trend based on reconstructed data, followed by a sharp increase based on observational data. In fact, it looks a bit like a hockey stick. Where have I seen that before?

    [Response: We’ve discussed this point already in some level of detail in “Did the Sun hit record hights over the last few decades?”. -mike]

  2. Steve Bloom:

    Beta imminent, possible Gamma on the way: http://www.wunderground.com/blog/JeffMasters/show.html . A week ago I was guessing Delta for the final tropical storm of the season; now Epsilon may be conservative.

  3. Stephen Berg:

    Re: #102,

    The waters of the entire Caribbean and almost all of the Gulf of Mexico are above the 26 C (c. 80 F) threshold required for tropical storm formation. Some of the waters are even above 29 C still. It looks like (to me) the hurricane season will be extended. For how much longer than usual, I’m not sure.

    Perhaps, we’ll get several more letters into the Greek alphabet. (Here’s hoping none of these storms are retired, or else they’d have to use a different alphabet next time.)

  4. wayne davidson:

    # 103, It may take a long while before a cycle theorist comes up with a past example of such an extraordinary year. A clear retrospective from our best Climatologists are needed now, they can lay to rest many weak ill researched theories as they clearly can not explain this year.

  5. Gerald Machnee:

    Several factors other than SST will determine when the hurriane season will end. Even if SST Temperatures continue above 26 C that alone will not develop hurricanes or extend the season.

  6. Dan Allan:

    I still wish someone explain why models do not predict more hurricanes (only stronger ones) owing to AGW. One year doesn’t prove anything, what is interesting about 2005 season is that it shows the obvious: that higher SSTs extend the season in both directions, and extend the region of the ocean in which hurricanes may form. All of which, absent other factors, would seems to lead to an increase in both strength AND number of storms.

  7. Gerald Machnee:

    Re #106 – The higher SST’s would suggest that there is a larger area over which hurricanes could develop so this leads to a higher number. But in order to develop you need several other factors including a wave or impulse to start it. These are usually spaced out a bit so there will be an upper limit to the number that will develop. The beginning and end of the season is also controlled by the large scale pattern. As the high over the Atlantic drifts southward the season will end. Hope this helps somewhat.

  8. Dan Allan:

    re 107:
    Well…not anything I’m not aware of. So you need a wave or impulse to start a hurricane. So, if a larger portion of the ocean is of 26c or higher, that is just more area for waves and impulses to drift over and develop into TCs. As to length of season, yes, part of the end is the change in atmospheric conditions, but it is also cooling SSTs. For example, almost the entire north atlantic has been unfavorable for TC development the last week, but the SSTs are still so high that one of the only areas where a hurricance could conceivably form just formed one.

    This year had the busiest July on record and I believe also the most active October. The season seems extended.

  9. Stephen Berg:

    Re: #105: “Several factors other than SST will determine when the hurricane season will end. Even if SST Temperatures continue above 26 C that alone will not develop hurricanes or extend the season.”

    True, although SSTs are a principal determiner of tropical storm production.

  10. Gerald Machnee:

    It is pointless to debate which is the “most important” but the following 3 factors are all required. Removing any of them will essentially kill a hurricane or result in no development.
    * Warm sea surface temperatures.
    * Light winds aloft.
    * Rotation, or spin.(caused by the impulse or wave)
    One of the latest hurricanes was in December.

  11. Stephen Berg:

    Re: #110,

    Seeing that “Light winds aloft” and “Rotation, or spin (caused by the impulse or wave)” usually occur throughout the year, but SSTs above the threshold do not, should SSTs warm to the point where SSTs are above the threshold throughout the year, it is conceiveable that the hurricane season could be year-round, or at least the season could be extended greatly.

  12. Gerald Machnee:

    RE #111 – The light winds aloft in the hurricane prone areas do not occur year round, so that is one of the main reasons the season ends.

  13. Dan Allan:

    There is no one day when the winds aloft suddenly make hurricane development impossible during the fall. It is a gradual process. And it seems to me that during this transition-period, if SSTs remain above 26c over a larger part of the ocean, there would be more tropical cyclones.

  14. Gerald Machnee:

    Re #113 – And the transition period is now.

  15. Steve Bloom:

    Re #114 (GM): I think if you’ll look at the relevant web sites you’ll find that it’s not quite now. Right this moment things are not very favorable, but then such periods occur in the middle of the season. Overall, development over the course of the next couple of weeks looks reasonably favorable. We shall see. My guess remains Epsilon (i.e., three more tropical storms for this season).

  16. Stephen Berg:

    Maybe the public is catching on…

    CNN/USA Today/Gallup Poll. Oct. 21-23, 2005. N=1,008 adults nationwide. MoE ± 4.

    "Thinking about the increase in the number and strength of hurricanes in recent years, do you think global warming has been a major cause, a minor cause, or not a cause of the increase in hurricanes?"

    Major Cause / Minor Cause / Not a Cause / Unsure
    % / % / % / %
    36 / 29 / 30 / 5

    Sorry the alignment was not so good.

  17. Pat Neuman:

    Re: 99

    > Quote by Andrew Dodds/ If I recall correctly, the time frame from 70 to 50 million years ago accomodates the opening of large chunks of the atlantic and finally the Artic ocean, allowing an ocean circulation regieme dominated by temperature difference instead of salinity differences. So in the late Cretaceous, the entire ocean would have been much warmer than today, and hence the same mass of water would occupy a greater volume. Even though the global surface/atmospheric temperatures may have been higher in the early Eocene, I don’t think this extends to the deep ocean./ End Quote < -------------------------------------------------------------------- My comment: I think I see that. Perhaps that explains the methane burbs which preceded the Paleocene Eocene Thermal Maximum (PETM 55 mya), and the great loss of marine species versus the limited on extinctions on land, even though there was more rapid warming on land versus oceans.-------------------------------------------------------------------- > Quote by Andrew Dodds/ Additionally, there is a relation between ocean basin volume and seafloor speading rates, the higher the spreading rate the higher sea level is for a given climate/ocean temperature. End Quote < -------------------------------------------------------------------- My comment: I'm not sure where Antarctic was 70 million years ago, but reports show that India was moving into Asia about 50 million years ago when the Himalayas were built. I suppose the seafloor speading rates were higher 70 mya versus 50 mya. Might that be the biggest reason that Florida-Texas had swamps instead of ocean over them? -------------------------------------------------------------------- > Quote by Andrew Dodds/
    However, this is a very hard relationship to bring out, because more seafloor spreading means more subduction and hence higher CO2 volcanic emission rates. So are your higher sea levels a result of ocean basin volume changes, ocean temperature changes or both? These are non-trivial questions to answer. Overall, direct comparisons of periods in earth history 30 or more million years apart are not simple. But it does not appear that N America was underwater during the Eocene. End Quote < -------------------------------------------------------------------- My comment: I agree, > it does not appear that N America was underwater during the Eocene. < ----------------------------------------------------------------------------------------------------------- .. http://www.scotese.com/Default.htm for a closer look, …

  18. Pat Neuman:

    Re 99 should be: …
    Thus, global atmospheric temperatures were higher in the early Eocene (55-50 mya) than in the late Cretaceous (70-80 mya) while the deep ocean waters were cooler in early Eocene than in late Cretaceous. That would explain the lower sea level conditions of the early Eocene versus the late Cretaceous, even with the atmosphere hotter during the early Eocene than the late Cretaceous. The answer is in thermal expansion of the ocean waters, which was less in the early Eocene than in the late Cretaceous due to greater temperature stratification of ocean water is the early Eocene versus the late Cretaceous. I’m not sure we know much about the significance of effects of differences in salinity and seafloor spreading between the two periods, nor in the effects of the positions of the continents during the two periods. I think the most significant difference that’s responsible for the greater stratification during the early Eocene compared to the late Cretaceous is what the longer term climates were like preceding the two periods. The climate preceding the late Cretaceous (by 10s of myrs) was warmer than the late Cretaceous, but the climate preceding the Paleocene/Eocene Thermal Maximum (PETM) was colder, by myrs, than the early Eocene (52 mya) period. The 15 myrs preceding PETM, from 55mya to 70 mya, included the K/T event 65 mya, of which there is still much uncertainty about what really happened to climate during that short period of geologic time.

  19. Pat Neuman:

    Re: 188 concerning differences in sea level 70 mya and 50 mya:

    The answer is in thermal expansion of the ocean waters, which was greater in the early Eocene than in the late Cretaceous, due to greater temperature stratification of ocean water is the early Eocene versus the late Cretaceous.

  20. Mark A. York:

    How about this statement I just recevied denying global warming:

    “As to the global warming issue, the argument is so full of hype and scare tactics that I for one have decided that it is a political argument and not a scientific argument at all. In fact, while there is some evidence of a shrinking arctic ice cap in the Beaufort sea areas over the last decade, there is growth in the iceland glacier one of the largest in the world, there is growth in the section of ice due north of Canada (a map that Mark York put up) and there is a significant amount of research that shows that the antarctic ice cap is growing fairly rapidly while the Ross Ice shelf is shrinking.”

    He didn’t cite his source only the belief.