Of course, the expansion of the tropics could be seen as a good thing for the planet and all things that inhabit it.

Hypothetically speaking.

By the way, this supposition is proven every year in the migration of both animals and humans to warmer climes as the winter approaches.

As Elliot astutely notes, the potential negative effects are unproven.

Do we need any comments seems pretty obvious to me anyway?
http://www.ssmi.com/msu/msu_data_description.html#msu_amsu_trend_map_tls
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.jpg
http://arctic.atmos.uiuc.edu/cryosphere/IMAGES/current.365.south.jpg
its becoming a trend me thinks LOL

. "At this stage, hype and supposition leads solid science by an appreciable margin."

No kidding!

How about creating a title for an article stating as fact:

"Global Warming has Caused Expansion of Tropics"

Only to fill the article with "may" "might" "could be" "who knows"

Talk about hype and supposition!

Expanding tropics?? Well, with my "Tunnel" idea the tropics are sure to shrink in size if we need them to as the "Tunnels" can regulate the climate. Computer modeling will also prove this to be the case.

Mr. Abrams summed the situation up rather succinctly with this remark-

At this stage, hype and supposition leads solid science by an appreciable margin.

According to some, there is no AGW signal in the tropics, despite the fact that geopotential heights throughout the tropics have risen over the past thirty years. Go figure.

A hypothetical question to the AGW community.

It appears from these NOAA maps that La Nina is fading. Suppose that six months from now, temperatures are still cooler than the models predict. How would that impact your belief system?

http://www.ncdc.noaa.gov/oa/climate/research/sst/ani-weekly.html

let's stick to the science, and remember nothing in nature happens overnight. We need to let the science with new instrumentation find the trends in all the background noise of everyday weather.
Fact the world is warming, long term this prove's out. Are we to blame? You only need to see grid lock in a major city of your choice, or walk thru a heavy industries area to know we are not helping. We need to put our collective heads together and get on with solutions. Man-made or natural or both, If we humans want to continue to
live here we need co-operation.

The February temperature map is out from GISS. Consistent with the UAH and RSS data, February was warmer (relative to normal) than January, although (due to differences in data sets) the calculated temperature values are different. Have we reached the low point of the La Nina-related temperature drop, or is this just a momentary pause in a larger downturn? I tend toward the former, but only one thing is certain....

Time will tell.

According to a review by MSNBC of the article referenced by Mr. Abrams, there was no conclusion drawn by the author, Dian Seidel of NOAA, that global warming is causing this expansion of the tropics. She stated that it is a possible cause but other causes such as depletion of the ozone layer, and changes in El Nino are also candidates.

Other scientists are quoted and they cover the waterfront of opinion on just what is causing these observed changes. It's an interesting read and I am pleased to see that MSNBC is reporting it objectively as the title is:

"Tropics widen, fringe areas drier, experts say. Not clear if changes are due to warming, El Nino or both"

Here is the link: http://www.msnbc.msn.com/id/22082965/wid/18298287/

Six out of seven continents were below normal temperatures last month, and almost the entire tropics were below normal.
http://www.remss.com/data/msu/graphics/tlt/medium/global/ch_tlt_2008_02_anom_v03_1.png

Only western and northern Europe were above normal. North and South America, Asia, Africa, Australia and Antarctica were all cool.

Very similar to January.
http://www.remss.com/data/msu/graphics/tlt/medium/global/ch_tlt_2008_01_anom_v03_1.png

Not exactly what the models were predicting....

Well....the Sahara desert is expanding south 30 miles a year. BUT is this also due to 'global warming' or is the desert expansion simply a factor of its own bulk, feeding upon itself. Equatorial air that is falling prevents most air from rising thus creating regions nearly devoid of rainfall. This is not global warming but simply a natural cycle. It is not a static natural cycle.

The expansion of the tropics is likely a natural cycle also as there is nothing inherent where the earth has not 'been there, done that'....

are the tropics expanding or are they shifting northward as the polar dynamics might be suggesting

"All of these hypothetical effects and suppositions are subject to change as research continues. At this stage, hype and supposition leads solid science by an appreciable margin."

*sigh* Please be more careful with your wording, Elliot. "Hype" isn't short for "hypothetical," and the latter term itself casts many of the article's findings in too weak of a light.

Also, I think both this post and yours leave readers confused on a couple of points. To clarify:

That the tropics have expanded is unequivocal. Climate models predicted just such an expansion as warming progresses. The observed expansion greatly exceeds the predicted amount, but the article notes that this may be because the models fail to account for stratospheric influences. That the expansion is a result of warming is fairly certain since there is no other explanation. The full text of the article is here, BTW.

One of the important consequences of the tropical widening (which effectively compresses everything pole-ward) is discussed in this important recent article describing the intensification (again from observations rather than models) of the westerlies over the Southern Ocean. This paper IMHO might turn out to be the most important of the year because of its immense implications for both our understanding of the climate system and future climate change.

Finally, as you probably know your opposite number over at TWC has spent considerable time documenting specific atmospheric and weather changes that could be results of the tropical widening. It would be interesting to get your views on his work.

Mark,

According to some, there is no AGW signal in the tropics, despite the fact that geopotential heights throughout the tropics have risen over the past thirty years. Go figure.

This is a blank statement, can you elaborate?

What caused the rise?

How much have they risen?

What is the effect of this rise?

Thanks,

Steve

Consistent with the UAH and RSS data, February was warmer (relative to normal) than January

Hi Travis,

Wow! Quite a complex, obfuscatory and misleading statement there. RSS data showed below normal temps for February.

GISS showed a huge area of 4-8 degree above normal temps across northern Europe and Siberia (wildly distorted in his projection.) RSS uses a much more accurate projection and found not a single spot >4 degrees above normal on the planet.

There are very good reasons not to take GISS 1200 mile maps seriously.

1. Hansen interpolates across vast regions with no data

2. Hansen uses map projections which hugely distort the Arctic

3. Hansen's temperatures are considerably higher than everyone else.

Steve Bloom,

You seem quite knowledgable on expanding tropics. In your expert opinion did the Tropics shrink during the Little Ice Age?

If they did, would you expect the tropics to expand once the cool period was over?

Have the tropics been expanding ever since the end of the last glaciation?

Where exactly are we in the glacial-interglacial cycle?

Thanks,

Steve

" You only need to see grid lock in a major city of your choice, or walk thru a heavy industries area to know we are not helping"

You said stick to the science, so where is the science in this statement?

Patrick,

I was not making a statement about accuracy of the GISS data and analysis, nor was I making a claim about how far global temperatures are from normal. I was simply pointing out that the direction of temperatures between last month and this month in all three datasets is consistent. My own interpretation of the data does not change the data itself.

If you want an analysis of temperatures compared to normal, RSS was the only one of the three that showed temperatures below normal (-0.007), but again, due to a difference in datasets, the values provided are insignificant. What we CAN infer from the data is that February global temperatures were close to "normal."

RSS data showed below normal temps for February.

Quite a misleading statement for yourself. RSS showed a temperature 0.007 degrees below normal. Aren't you the one who has previously noted how ludicrous it is to try to define a single "global" temperature, much less one that is accurate to one-one thousandth of a degree?

Please correct the post: Elliot said "change," not "chance."

Reply: Will do, thanks for pointing out my mistake

loub, the expansion is more or less equal to the north and south.

I imagine the tropics expand and contract, just as the Atlantic and Pacific warm and cool with various cycles. The tropics were likely larger during the MWP and smaller during the Little Ice Age.

However I will note I have seen the range of cardnels, mocking birds, and 'possum expand up into New Hampshire during my lifetime. After this winter, they may be thinking twice about the move north. (I know a lot of the humans are.)

Mark,
Rising geopontential heights isn't an AGW signal. The atmospherice thickness of the tropical zone hasn't increased. As I said in earlier posts, you need to calculate the atmospheric thickness of two or more geopotential heights, not just one level. Tropical warm pools aloft would be most obvious in the 700mb to 500mb thickness gradient aloft. This obviously has not occured.

Steve Bloom,

This is off topic on this thread, but I'm going to throw it at you anyway. We've talk quite a bit about SH sea ice in the past, but there are a few points that I still think need to be looked at.

On more than one occasion when I've brought up the upward trend in SH sea ice you've said it wasn't a significant increase. Fair enough, but here are a couple of questions. Last years Arctic sea ice saw a negative anomaly of around 3 million sq km in October 2007. I would say that's a significant drop. Conversely, in December 2007, SH sea ice had a positive anomaly of 2 million sq km. I would say that is also significant? Do you agree?

Presently, NH sea ice is around a half million sq km below normal. SH sea ice is around 1 million sq km above normal. Which one is more significant or are neither really significant at this point? Either way there is presently more global sea ice than normal.

Some other facts: NH sea ice coverage is the highest since 2004 and approximately the same as 1996. SH summer sea ice coverage was more than the last two years and, by all accounts, was the 3rd or 4th highest coverage in summer since 1979.
In addition, the summer melt season in Antarctica clearly ended early and sea ice is increasing rapidly.

The point is, as someone who is skeptical of AGW, I'm being expected to buy into the idea that Arctic sea ice is shrinking because of GW. At the same time I'm expected to either ignore increases in sea ice around Antarctica or believe, in fact, that it is also being caused by AGW. Do you see the problem with that logic?

Will your opinion on this issue be influenced if Arctic sea ice remains higher this summer than last year?

Also, regardless of whether you consider it statistically significant or not, it's clear that SH sea ice continues to trend upward and shows no signs of a decline? Do you agree?

Hi Travis,

I said -

RSS data showed below normal temps for February.

You said -

RSS showed a temperature 0.007 degrees below normal.

You described my statement as being misleading. Interesting....

iceman, I think we've covered all of this ar one point or another in various threads, but OK:

This is off topic on this thread, but I'm going to throw it at you anyway. We've talk quite a bit about SH sea ice in the past, but there are a few points that I still think need to be looked at.

On more than one occasion when I've brought up the upward trend in SH sea ice you've said it wasn't a significant increase. Fair enough, but here are a couple of questions. Last years Arctic sea ice saw a negative anomaly of around 3 million sq km in October 2007. I would say that's a significant drop. Conversely, in December 2007, SH sea ice had a positive anomaly of 2 million sq km. I would say that is also significant? Do you agree?

For a little context, look at the absolute amounts for north and south. The south does not look very interesting, noticing in particular that there was an almost identical high/low seven years ago. More is going on in the north, but even so bear in mind that the major change there is not in area but thickness.

Presently, NH sea ice is around a half million sq km below normal. SH sea ice is around 1 million sq km above normal. Which one is more significant or are neither really significant at this point? Either way there is presently more global sea ice than normal.

NH winter ice is expected to more or less recover (for a while, anyway) even if we start seeing ice-free summer periods. There's nothing significant here.

Some other facts: NH sea ice coverage is the highest since 2004 and approximately the same as 1996. SH summer sea ice coverage was more than the last two years and, by all accounts, was the 3rd or 4th highest coverage in summer since 1979. In addition, the summer melt season in Antarctica clearly ended early and sea ice is increasing rapidly.

We just came through an uusually cold season. All of these effects seem consistent with that.

The point is, as someone who is skeptical of AGW, I'm being expected to buy into the idea that Arctic sea ice is shrinking because of GW. At the same time I'm expected to either ignore increases in sea ice around Antarctica or believe, in fact, that it is also being caused by AGW. Do you see the problem with that logic?

As noted, the Antarctic trend is not statistically significant. Even so, there is an AGW explanation for it, which is that the expansion of the tropics has resulted in a slight cooling and freshening of surface waters north of Antarctica.

This helps make a good point about the lack of comparability between the northern and southern ice since it's not possible for such an effect to occur in the north. Expecting that the two areas should behave consistently is a bit like taking glaciers in two different regions and expecting they will behave the same. They might, but if their circumstances are sufficiently different they won't.

Will your opinion on this issue be influenced if Arctic sea ice remains higher this summer than last year?

Not especially. Even with a sharply declining trend it would be unusual for there to be two record years in a row. The next three or four years will tell the tale, although if Maslowski is correct we will see sharp record lows nearly every year for the next five years or so until we reach an ice-free state (albeit probably fairly brief; also note that "ice-free" means that there will be plenty of remnant ice left around the shorelines.)

Remember also that what we're really talking about is the entire climate system in the Arctic, the ice extent being basically a symptom of that. For example, a huge factor in last year's melt was the relative lack of cloud cover. Is local climate shifting such that the lack of clouds will be persistent? If cloud cover is low again this year (and we'll be able to see this effect within a couple of months) and if the encroachment of warm water from the Atlantic continues as it has been, conditions will be ripe for another record low.

Also, regardless of whether you consider it statistically significant or not, it's clear that SH sea ice continues to trend upward and shows no signs of a decline? Do you agree?

I think I answered this above.