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Riccardo at 02:15 AM on 4 May 2010Why are there fewer weather stations and what's the effect?
Berényi Péter, I know Spencer blog posts and they are not related to station drop out nor with your analysis. The replications I was talking about are on the effect of the dropping of stations and they have done it properly, contrary to your analysis. -
Ron Crouch at 02:15 AM on 4 May 2010Rain in the Canadian High Arctic in April?
#10 Berényi Péter While the Metar report you supplied for Clyde River Apr 18, 1973 clearly states rain it also shows no accumulation. In contrast the Environment Canada Daily and the Environment Canada Hourly records indicate no precipitation at all. Now the Metar report you supplied for Pond Inlet for Apr 25, 1985 clearly states "fog,rain,snow" with an accumulation of .1 cm. The Environment Canada Daily and the Environment Canada Hourly records clearly indicate snow on that date with total precipitation registering .6 mm. Moving on to Isachsen on June 7, 1975 The Metar report indicates fog with no accumulation of precipitation. On June 4, 1975 the Metar report does indicate "rain,snow" with no accumulation. So let's see what Environment Canada has to say about those dates on a daily basis. Well June 7 shows rain accumulation of .3 mm and June 4 shows the same with a trace of snow. So moving on to the hourly report for June 7 it indicates drizzle and fog throughout the day. Now on June 4 the hourly report indicates rain and snow changing to rain late in the evening. So yes the claim that June 7, 1975 being the first recorded rainfall at Isachsen is incorrect as it clearly took place three days earlier on June 4. So we'll have to give David Phillips at least an "E" for effort on that one. Now for the final item which is May 1988 in Alert. The Metar record supplied shows a total of 4 cm precipitation for the month and shows no precipitation on the 21st and .1 cm on the 22nd. So what do the Environment Canada records say. Well it shows a .2 mm accumulation of rain on May 21 followed by a trace of rain on May 22. So in conclusion, seeing that we are dealing with Canadian Climate Records then it is only appropriate when doing an analysis that we use the official Canadian documents from Environment Canada. Other than the small blurb that David had over June 7, 1975 for Isachsen, I'd say the climate record contentions are fairly spot on. -
Tom Dayton at 01:45 AM on 4 May 2010Why are there fewer weather stations and what's the effect?
Berenyi Peter, I'll try to be clearer: In the real data analyses, the missing/dropped/discontinued data do not contribute to the overall average trend, because those data are ... missing. In contrast, in your math experiment, the data you dropped did contribute to the overall average trend. -
Berényi Péter at 01:42 AM on 4 May 2010Why are there fewer weather stations and what's the effect?
#37 Tom Dayton at 00:16 AM on 4 May, 2010 Every month, more get added as the data dribble in. They do dribble. Records updated in GHCN (v2.mean) between 2010-03-19 & 2010-05-03 according to year:2005: 9
Data earlier than 2005 are not even dribbling.
2006: 11
2008: 13
2007: 14
2009: 213
2010: 1292 -
Juergen Wanninger at 01:33 AM on 4 May 2010Flowers blooming earlier now than any time in last 250 years
If I'm reading the diagram correctly, the botanical spring has moved two or three days forward within the last 250 years. Aren't you aware, that this will show that earth has NOT warmed since that time in any way? Due to earth's axis precession once in 25800 years, the seasons will move completely through our calender in that time. So spring for example should move forward for about 3.6 days in a 250 years period. So I think the result of this paper is the confirmation of a little COOLING of earth within the last 250 years. Quite a good argument for climate scepticals! Isn't it? -
Rob Honeycutt at 01:13 AM on 4 May 2010Rain in the Canadian High Arctic in April?
I have to agree with CO2 (#14). Hail is formed by rising moisture in thunderheads that can sometimes reach over 50,000 feet high. Such storms only form in the presence of warm moist unstable air (summer). One would expect it to be warm at the surface when getting hail. -
Tom Dayton at 00:16 AM on 4 May 2010Why are there fewer weather stations and what's the effect?
Berenyi Peter, you are incorrectly assuming that your purely mathematical experiment is an analog of the actual station dropout data. In your experiment, you split the data at an exact midpoint of time, and deliberately and perfectly split lower-trending from higher-trending data. Those choices of yours are what led to--indeed, forced--the existence of the regression to the mean that you found, purely due to the math. You might just as well have removed all the lower-than-average anomalies and expressed shock that the remaining anomalies are higher-than-average. It's the combination of lower with higher that defines the average! In contrast, the real data analyses' station discontinuation point is not at the time midpoint, but long after. Also, the discontinued data are not selected for discontinuation because they trend lower or higher. Indeed, the majority are discontinued only temporarily. Every month, more get added as the data dribble in. -
CO2 at 00:01 AM on 4 May 2010Arctic Sea Ice (Part 1): Is the Arctic Sea Ice recovering? A reality check
CBDunkerson at 04:32 AM on 13 April, 2010 I've used identical arguments when discussing sea ice extent. We also have to differentiate between the arctic and the antarctic. Antarctica's sea ice is unimpeded, the arctic is not. Once the arctic sea ice reaches its limits east and west, the only growth area's are south and north. -
CO2 at 23:47 PM on 3 May 2010Rain in the Canadian High Arctic in April?
HumanityRules #7 Hail is formed in severe thunderstorms reaching great hight. The surface temperature has no more to do with this than creating the conditions that formed the thunderstorm to begin with, which may be 20,30 or 40 degrees C. Are we talking climate change? -
Berényi Péter at 23:22 PM on 3 May 2010Why are there fewer weather stations and what's the effect?
#35 Riccardo at 17:13 PM on 3 May, 2010 I cannot see the rationale of the station selection criterion The rationale, as I have already stated, is the fact that dropped stations have slightly higher warming trend prior to dropout than the rest. the very same results has been replicated several times Yes, but all of them have found the right answer to the wrong question. Except Roy Spencer of course, who did something entirely different. He actually collected some more data, which is the proper thing to do anyway. He uses ISH data from ftp://ftp.ncdc.noaa.gov/pub/data/noaa/ but says they are only accessible for ".gov or .edu domains". He may be right. He checks CRUTem3NH against it and finds no serious difference, provided an increasing urban heat island effect is not taken into account. Satellite data are not used in this analysis. However, there ara also several follow-up articles on his website including Spurious Warming in the Jones U.S. Temperatures Since 1973 and The Global Average Urban Heat Island Effect in 2000 Estimated from Station Temperatures and Population Density Data His population density / station warm bias graph is particularly interesting.
This effect alone can be responsible for a good portion of "Arctic Amplification" (because population density is pretty low there).
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Dennis at 22:39 PM on 3 May 2010Rain in the Canadian High Arctic in April?
Re: CoalGeologist #4 wrote "It is a 'double edged sword' to use single events as providing proof that AGW is occurring, when certain other rare "events" such as this past cold, snowy winter in the eastern U.S. could potentially be cited as proof that AGW is a 'hoax'." The Eastern U.S. this past winter may indeed be categorized as "snowy," but -- depending on how you categorize "Eastern U.S.," it is debatable to call it "cold" (or, more accuirately, "colder"). While Washington, D.C., had record snowfall totals from December through February, March recorded the forst time since record keeping began that the temperature did not drop below freezing (even overnight). I leave up to the scientists if increased precipitation is linked to a warming world. However, ceteris paribus, higher temperatures are. So, I agree with coal geologists, and have found that the AGW-is-a-hoax crowd have ignored the temperature record int he evidence. -
Mythago at 21:34 PM on 3 May 2010Rain in the Canadian High Arctic in April?
I won't profess to having had time to go through reams and reams of data but to my mind it is possible for all unique or rare or even bizarre events as being nothing more than pure fluke chances of something having happened. Micro-climates exist all over the place. Here in North Oxfordshire we got a massive winter snowfall compared with the last 15 years that I can recall. Is that bizarre? Is that proof that AGW is not happening or is happening? I firmly believe that we have influenced the natural cycles of climate change, which would normally take millennia to occur, by pumping out massive amounts of all manner of polluting gases (AGW gases) and it is obvious that the climate is warming from very basic evidence but I really despair when one-off events are even hinted at as evidence to prove or disprove what is a very obvious trend which is already being proven and is based on global scale, long term evidence. I reckon someone was fishing by putting out the bait and you were conscientious enough to want to genuinely want to answer in as honest a way as possible. However beware the origin of this item. They may seem all interested and curious on the outside but on the inside they are possibly looking for a fight. I bet they try to use some of your article to suggest something alternative and argumentative later on elsewhere. The sceptics are getting desperate for an argument that they can say disproves AGW and will dig as deep as is possible and use whatever tactic is readily available. As the old saying tells us, 'There are lies, damn lies and statistics'. The lists you quote are incontrovertible evidence but they prove nothing unless you try to say they do with some argument, no-matter how well founded, that shows reasonable proof of a pattern or trend. That's when the sceptics strike with counter evidence. Its all a silly game and as far as I am concerned its a waste of time. Lets just put down the charts and tables and get on with abandoning fossil fuels and start being realistic about the planets ability to sustain us as a species. AGW! Its happening. We need to prepare for the worst case scenario and no amount of tables and charts and nit-picking over micro details will stop it happening. Have a nice day. Kev C. -
HumanityRules at 21:17 PM on 3 May 2010Rain in the Canadian High Arctic in April?
Ron, Just to prove I can do something as boring as you in the name of enlightenment I decided to have a look at some of those high Canadian records. I choose Eureka because from the map it looked like the closest to the site of this rain. The max temp in Apr 2010 was -4.7oC (-5.2oC on the weekend in question). So I checked for some other 'high' temps in Apr at Eureka. Here's a few of the balmiest Apr days (year, day in Apr, temp oC) 2010 23rd -4.7 1948 28th -5.0 1951 30th -6.1 1953 25th -3.3 1961 19th -6.7 1971 26th -2.8 1975 28th -5.0 1979 12th -3.1 (these are not all of them, just the warmest in a particular year and I reached my boredom threshold in the mid 80's) While unusual it looks like the temps in 2010 aren't unique. It's a shame the records don't go back further because my understanding is that the 1930's and 1940's were a period of warmer arctic temperatures. Going through the record I noticed all forms of precipitation are rare in Eureka in Apr (average for whole of Apr is 3.5mm). Apr 2010 had 15mm of precipitation. Hope this helps to stop people going off the deep end :) -
Berényi Péter at 20:36 PM on 3 May 2010Rain in the Canadian High Arctic in April?
There is a METAR record for Clyde, Nunavut, 1973 April 18, 20:00 AST (70.48 N, 68.52 W) indicating some rain. Same for Pond Inlet, Nunavut (72.70 N, 77.97 W) on 1985 April 25 01:00 EST and several more on 1995 April 27 Unfortunately Isachsen, Nunavut (78.78 N, 103.53 W) has only reported on 15 & 16 April 2010, so the anecdotic claim about April's rain on 24/25 is not supported by hard evidence. There was some rain there indeed on 1975 June 7 as claimed by the article. However, it could not be the earliest recorded rainfall on that spot, for there was also some rain there three days erlier. And of course there was no rain at all in May, 1988 at Alert, Nunavut (82.50 N, 62.33 W). On the other hand, there was some rain there last year on April 3 (maximum temperature for the day is -32 °C!). That much about reliability of press releases. -
JMurphy at 20:13 PM on 3 May 2010Rain in the Canadian High Arctic in April?
RSVP, your Spanish examples are no doubt uncommon but hardly bizarre, I believe. Barcelona's 'maximum number of snow days in a month' (4) occurred in Feb 1938. Mallorca's maximum, (3) occurred in Jan 1985. The overall picture for the last Spanish Winter doesn't suggest any particularly bizarre events. In fact, the only unusual snow events occurred in A Coruña (Airport), Santander, Madrid (aerodrome of Cuatro Vientos), Toledo, Valencia (Manises airport) and Seville (Airport), where the number of days of precipitation in the form of snow surpassed the previous maximum values for January. On checking those stations, though, you will notice that accurate readings only began in, respectively, 1971, 1945, 1982, 1966 and 1951. (I haven't included Santander because although readings began back in the 20s, it is still showing 1956 as the heaviest year). Since most other places I have checked show a maximum snowfall around the 1930s or 50s, it can be perhaps claimed that the above stations may well have been higher then also, if only accurate readings had been taken at the time. You can check them all here. Uncommon weather indeed but not bizarre, surely ? -
wanderers2 at 19:40 PM on 3 May 2010Rain in the Canadian High Arctic in April?
I was fortunate, as a 19-year-old, to get a job in the Canadian High Arctic (as an assistant carpenter/plumbers/electrician's helper). Yes that meant I visited places like Eureka, Resolute, Mould Bay, and Alert (Weather Station Isaachsen had already been closed by that time). Sighting narwhals from the air (thank you De Havilland Canada for building the incomparable twin otter) was fun. Encountering a polar bear on the ground (me carrying no gun and hiking alone and therefore illustrating the stupidity of my youth) was not. But seeing thousands of nesting murres, or the occasional snowy owl or snow bunting. That experience drove me towards a lifelong pursuit of ecology. Recently I have returned to the arctic, where I consistently see, and hear, from aboriginal persons, hunters, ornithologists, and others: that trends are all congruent with what is expected or projected by climate models. John, you do a great service with this website, and the best part of it is to provide access to the primary literature that others might have a hard time finding. If I had one request it would be to further synthesize some of the recent phenological papers. Thank you. -
HumanityRules at 19:36 PM on 3 May 2010Rain in the Canadian High Arctic in April?
So normal April temps at Resolute and Eureka are -20oC. Apr 24th and 25th 2010 temperature was around -10oC (as high as -6oc). Seems rain wasn't the only strange weather that weekend. -
Argus at 19:12 PM on 3 May 2010Skeptical Science talk at University of Qld on May 7
RSVP is right here, of course. Nature adapts all the time, and it works faster than we may think sometimes. I sense a kind of anxiety with many of the debaters on this site. They are always so worried, verything is so alarming all the time, and status quo seems to be the only desirable future. -
HumanityRules at 19:08 PM on 3 May 2010Rain in the Canadian High Arctic in April?
If you want bizarre weather come to Melbourne. One summer day we had temperatures over 30oC followed by an evening hailstorm! How is the rain recorded? What was the temperature on the day? -
Berényi Péter at 17:46 PM on 3 May 2010What causes Arctic amplification?
#12 HumanityRules at 12:32 PM on 3 May, 2010 a little sceptical that there is a linear trend There are issues here indeed. Arctic sea ice extent reconstruction for the first half of 20th century at Cryosphere Today is higly problematic. The following book is a must-read for all serious students of the topic (even if it is mentioned at WUWT). Arctic Ice by Nikolai Nikolaevich Zubov, Moscow, 1943 (English translation 1963). -
Riccardo at 17:31 PM on 3 May 2010What causes Arctic amplification?
Frank, there is a very good reason for the warm water effect having a larger effect in winter, it's air temperature. Relative to the winter-summer temperature difference, water temperature is almost constant and not far from air temperature in summer. I'd also like to point out that the authors are smart enough to not confuse correlation with causation. Indeed their conclusions don't rely on the correlation but on the physics of the process. The correlation has been properly used to rule out other effects. It always surprises me when people think that reputable scientists (authors and referees) could make such trivial mistakes. Betting on a trivial mistake in a published paper, good chances are that we're missing something. -
Riccardo at 17:13 PM on 3 May 2010Why are there fewer weather stations and what's the effect?
In this blog are used to the strong but not supported claims by Berényi Péter. This is just one more example. Indeed, I cannot see the rationale of the station selection criterion nor how any reasonable judgement can be done on the global average temperature trend without proper gridding and averaging. Taking subsets and subsets of subsets is no easy task and the fact that the very same results has been replicated several times using different methodologies makes me think that the only possible conclusion from Peter's mathematics is that his selection criterion is biased. -
SoundOff at 16:24 PM on 3 May 2010Rain in the Canadian High Arctic in April?
Most parts of Canada had an exceptionally mild winter earlier this year. Witness the winter Oympics near washout in Vancouver. It was 25°C on April 2 in my area (Toronto) – the normal is 8°C for that date. That blew away the previous record of 20.6°C in 1967. Incidentally, I wore my winter coat only two days this past winter, unlike every day the previous winter. This anomalous weather must be credited to the recent El Niño, since global warming stopped a while ago according to skeptics. -
CoalGeologist at 16:16 PM on 3 May 2010Rain in the Canadian High Arctic in April?
Several weeks ago, I was enticed into an email "debate" with a AGW "skeptic" who argued that because February, 2010 was the first February on record when there were no tornadoes in the United States, this demonstrated (somehow?) that AGW wasn’t happening. I can’t say I understood his reasoning (if there was any!), but the question raised the issue of the distinction between "weather" and "climate". In this regard, it's best to conform to standard definitions, as appear below in my (overly-long!) post. As shown in the reply by RSVP @#2, using statistically rare "extreme weather events", or even more protracted "extreme climate events" to draw inferences regarding climate change is fertile ground for "cherry picking", and for this reason is best avoided. It is a "double edged sword" to use single events as providing proof that AGW is occurring, when certain other rare "events" such as this past cold, snowy winter in the eastern U.S. could potentially be cited as proof that AGW is a "hoax". Ultimately, climate is a statistical phenomenon. In this regard, single events can be measured in terms of their statistical likelihood, as has been done here. They do not, however, in and of themselves, describe climate, nor climate change, no matter how "bizarre" they may be. The recent flap over whether there has been statistically significant warming in the U.K. since 1995 demonstrates that even multi-year trends can be used to prop up invalid conclusions, if one approaches the topic of climate change with a biased agenda. For reference, the following definitions are from the Glossary section of the IPCC 2007 AR4 Report: "Climate": Climate in a narrow sense is usually defined as the average weather, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period for averaging these variables is 30 years, as defined by the World Meteorological Organization. The relevant quantities are most often surface variables such as temperature, precipitation and wind. Climate in a wider sense is the state, including a statistical description, of the climate system. In various chapters in this report different averaging periods, such as a period of 20 years, are also used. "Extreme Weather Event" AND "Extreme Climate Event": An extreme weather event is an event that is rare at a particular place and time of year. Definitions of rare vary, but an extreme weather event would normally be as rare as or rarer than the 10th or 90th percentile of the observed probability density function. By definition, the characteristics of what is called extreme weather may vary from place to place in an absolute sense. Single extreme events cannot be simply and directly attributed to anthropogenic climate change, as there is always a finite chance the event in question might have occurred naturally. When a pattern of extreme weather persists for some time, such as a season, it may be classed as an extreme climate event, especially if it yields an average or total that is itself extreme (e.g., drought or heavy rainfall over a season). "Climate change" Climate change refers to a change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer... [the definition continues, but the latter parts are not relevant here.] -
Jeff Freymueller at 16:09 PM on 3 May 2010Rain in the Canadian High Arctic in April?
Very nice detective work! Your last paragraph is well stated. If rain in April starts to be commonplace in these places, that would be empirical evidence for climate change. A single bizarre event, by itself, can be consistent with what is expected from climate change. But you can never be certain that a single bizarre event is really due to climate change, even if climate change makes it more probable. -
RSVP at 16:03 PM on 3 May 2010Rain in the Canadian High Arctic in April?
...before the Iceland volcano eruption. -
RSVP at 16:01 PM on 3 May 2010Rain in the Canadian High Arctic in April?
It was snowing in Barcelona, Venice and Mallorca a few months ago. How common is this? -
Jeff Freymueller at 16:00 PM on 3 May 2010What causes Arctic amplification?
Sea ice extent indeed has not changed much in winter (useful graph!), but sea ice THICKNESS has changed a lot at all seasons. The difference between the green curve for year X and the blue for X+1 has been growing over time, and that gives you the area covered by thin first year ice. And as noted in a recent thread here, overall volume is significantly reduced and thick multi-year ice is restricted to an ever shrinking area. Thickness is important because the insulating effect of the ice depends on the thickness of the ice, just like the thickness of the insulation in your house determines its insulation rating (given as Rn in the US, where n is a number). Heat can be transported through the ice in a couple of ways. One is by transport or percolation of water through the ice, but I don't know a lot about how important that is. Even with no water percolating through the ice, heat will be transported through the ice by conduction. The rate of heat flow for conductive heat transport in a uniform material is q = -k*dT/L, where k is a constant that depends on the material, dT is the temperature difference, and L is the distance between the hot and cold sides, in this case the thickness of the ice. The minus sign just means heat flows from hot to cold. If you cut the ice thickness in half, you double the rate of heat flow given the same temperature difference. As the ice gets thinner, the heat flow will be dominated less by conduction, and will approach the heat flow out of open water (heat flow won't go infinite). The thickness of the ice is likely to be a controlling scale for other modes of heat transport as well, but somebody else needs to pick up beyond this because this exhausts my knowledge of heat transport through sea ice. But the bottom line is that in autumn/early winter, there is a lot more open water than before, which then gets covered by thin ice, and the heat transport from ocean to the atmosphere is going to be a lot faster than it used to be throughout the entire winter. Compared to the Arctic atmosphere, the Arctic Ocean is a vast reservoir of heat. Yes, its very cold by ocean standards, but the value of T doesn't matter in the heat flow problem (except for radiation), only the temperature difference (dT). And in the winter dT is large and negative (atmo minus ocean). -
RSVP at 15:56 PM on 3 May 2010Skeptical Science talk at University of Qld on May 7
To Philippe Chantreau... Thriving of the Pine Beetle is simple proof that Nature is adapting quickly to the changes. -
KR at 12:54 PM on 3 May 2010Where is global warming going?
suibhne - first of all, my apologies, I was thinking of the wrong Trenberth reference. I believe that the "missing heat" thread is discussing that issue. As to your thought experiment of heating the entire earth and the large time constants - crust temperature rises ~20C per kilometer for the first ten kilometers, figure ~200C hotter than the surface 10 kilometers down, when you get to the mantle, where convection currents drop the gradient to 0.3C/kilometer. That means you would only see heating in the top kilometer or so; the rest of the planet is already much hotter, with the upper crust cooling through radiation to space. You won't be heating the mantle, let alone the core (5000-6000C). Warming the crust just slows the cooling of the core, it doesn't heat it. So if you run your calculations with the top 10km (a generous depth) of crust rather than the entire planetary mass, I suspect you will find the time constant for full solar irradiation heating much much smaller. I get a time constant of ~5 years for a 1C temperature rise, not 1080. If you just consider the top 1km, as the crust is 20C hotter below that, your time constant would be six months/degree C; actual thermal conduction speeds in the crust mean that the surface would be much hotter. That makes the 0.7C rise over the last 70-80 years attributable to a very small portion of total irradiance. Incorporating the entire planet in thermal inertia calculations makes no sense when 99.5% of the planet is 200-5500C hotter already. Radiative equilibrium simply describes a steady state situation where incoming radiation matches outgoing radiation - a simple balance of energy. I believe that's what you've described in your last post - an Earth system that cools or warms until it reaches equilibrium. I just have to disagree with your time constants. -
HumanityRules at 12:32 PM on 3 May 2010What causes Arctic amplification?
10.Frank I guess the theory goes less sea ice means greater transfer of heat between the ocean and atmosphere. I don't understand how this is greatest in winter and at the highest latitudes. This is both the time and region where sea ice has seen least change. An insulating cover of ice must be present at this time. How does the energy get through the ice? As Frank also mentioned there are questions about the temperature records. No buoy or ship data in winter at the highest latitudes and poor satellite coverage, where are the numbers coming from? (It's a pity the supplementary data isn't working) I'm also a little sceptical that there is a linear trend in winter sea ice over the period (1989-2008). The graph below (from Cryosphere Today) shows that winter sea ice recovered to it's early 20th century norm between 1997-2002. How is the winter sea ice a linear trend?
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Ken Lambert at 12:08 PM on 3 May 2010Tracking the energy from global warming
Joe #103 Joe, please convert your kW-hrs to Joules x exponent 10, and we can talk the same language. Interesting proposition with the permafrost, except for the mechanism of channelling all the 'missing heat' there. I don't have a number for the surface area of permafrost on the globe, but is you use roughly 29% land and 71% ocean, and then look at the 29% land and partition the permafrost as say 20% of the land area then you get 6% of the globe surface as permafrost - I think nearly all in the northern hemisphere. Now think about the mechanism gathering Dr Trenberth's global 'Missing' heat residual of 30-100E20 (Av 65E20) Joules into that 6% of the global surface area in a particular part of the northern hemisphere - given the fact that the heat imbalance is global and not directed to any particular spots on the planet. -
Ken Lambert at 11:55 AM on 3 May 2010Tracking the energy from global warming
Chris #103 "There really isn't any evidence that the sea level rise "starts to flatten in the last 7 years". " Except for the evidence of your own eyes. Do a least squares for the last 7 years Chris and you get closer to 2mm than 3mm, which is where we started this discussion. If you assume that Dr Trenberth's figures are roughly correct for glaciers (approx 1mm) and major ice sheets (approx 1mm) then all the recent rise can be accounted by ice and none by thermal expansion. No thermal expansion means no increase in OHC, which is where this blog started viz. the missing heat. -
Berényi Péter at 07:36 AM on 3 May 2010Why are there fewer weather stations and what's the effect?
#32 Marcel Bökstedt at 07:13 AM on 3 May, 2010 Can you think of a way of testing/debunking this hypothesis? Yes. As I have already mentioned, I am collecting recent data for stations dropped from GHCN. That should be enough to clarify things beyond reasonable doubt. -
Tom Dayton at 07:24 AM on 3 May 2010Why are there fewer weather stations and what's the effect?
Berenyi Peter, the name of the purely mathematical effect that Marcel explained to you is an example of "regression to the mean." You'd get the same effect even if the numbers had nothing to do with temperatures--they could be cow growth or purely abstract numbers. No UHI required. -
mspelto at 07:14 AM on 3 May 2010What causes Arctic amplification?
Frank there are several key points to consider first as is referenced by Screen and Simmonds, 2010:Serreze and others (2009) noted "Summer, by contrast, has seen a recent increase in the net surface heat flux (an increased net heat gain by the ice-ocean column). This is understood in that ice melt(phase change) and heating of the ocean mixed layer have limited the increase in the surface temperature and hence the upward longwave flux." Remember it is the end of summer and autumn which have the most open water, also recall it takes lots of energy to melt the ice. Also note the water is not in general warmer than the air in the summer and would not heat it appreciably if it is not. The water is increasingly warmer than the air in the autumn, as autumn progresses. That is a key to the ocean being able to heat the air above it. In particular the air near the surface. Another point they make is: "2) Consistent with an anomalous surface heating source, development of the autumn warming pattern aligns with the observed reduction in September sea ice extent, and temperature anomalies strengthen from the lower troposphere to the surface; 3) Recent autumn warming is stronger in the Arctic than in lower latitudes; 4) Recent low level warming over the Arctic Ocean is less pronounced in winter when most open water areas have refrozen;" The pattern does fit. Recall that this group used NCEP and JAR-25 data not just ERA-40. This suggest a very robust result and does support the joint effects of hypothesis a and b. -
Marcel Bökstedt at 07:13 AM on 3 May 2010Why are there fewer weather stations and what's the effect?
Bérenyi Péter> My hypothesis is that the effect you see in your A,B experiment is an "edge effect", coming from the fact that the stations with a high trend in the first 20 years will on average be in an unusually warm state in the year 20. I can't see why the stations which dropped out in the GHCN data would show a similar edge effect, but of course I might just be uninventive. Can you think of a way of testing/debunking this hypothesis? Or can you think of a way to produce an edge effect in the original situation? Another thing - I thought that when GHCN computes the trends, the stations which were dropped were dropped for the entire interval, not just for the last time period. So to check their method, we should compare 40 y average A with (the more correct) 40 average A+B, not with an average where we use 40 y of A and some years of B. Please tell me if I'm wrong about this. -
chris at 07:06 AM on 3 May 2010Tracking the energy from global warming
Ken Lambert at 22:27 PM on 2 May, 2010 "why not curve fit your whole graph - since 1993; which is 17 years of noisy data" We've done that already Ken - see my post #76 and #100. Least squares fit of the satellite sea level record (the "whole graph") gives a value somewhere above 3 mm.yr-1; e.g. from analysis of the "whole graph": (a) Beckley, B. D. et al. (2007) determine that the sea level trend is 3.36 mm.yr-1 (b) Cazenave and Llovel (2010) determine that the trend is 3.4 mm.yr-1 (see links in my post #100) (c) The solid line in my post #76 is a least squares fit to the full satellite sea level record. The fit is 3.2 mm.yr-1 (d) likewise Trenberth (see Trenberth and Fasullo 2010, link in John Cook's top post):"Since 1992, sea level observations from satellite altimeters at millimeter accuracy have revealed an essentially linear global increase of ~3.2 mm per year, with an enhanced rate of rise during the 1997–1998 El Niño and a brief slowdown in the 2007– 2008 La Niña."
There really isn't any evidence that the sea level rise "starts to flatten in the last 7 years". That's not to say that there might not be some reduction of heat uptake into the oceans. The data supports the conclusion that recently the mass component (land ice melt) has made a larger contribution to sea level rise [relative to the steric (thermal) component] compared to previous parts of the satellite record. This isn't unexpected considering that the last 7 years has coincided with the descending limb of the solar cycle which has been anomalously extended through cycle 23. However, considering that sea levels continue to rise at upwards of 3 mm.yr-1, it's difficult to draw major conclusions about ocean heat inupt from sea level change from the short period of the last few years, other than that the oceans must almost certainly be continuing to take up heat (because sea level rise can't be fully accounted for by the mass component). Perhaps one might suggest that sea levels should be rising a bit faster now than a decade ago; it wouldn't be surprising if this is observed during the next 5-6 years as the sun "swings" upwards through the rising limb of the solar cycle... -
Geo Guy at 06:30 AM on 3 May 2010Accelerating ice loss from Antarctica and Greenland
Notwithstanding all of the argument presented here, there is another strong possibility that something else is causing the melting of the Greenland ice cap. Specifically the melting could be occurring at the base of the ice sheet rather than at the top. If this indeed is the cause, then the global warming arguments simply do not hold any water with regards to the melting. Another possible source for the melting is solar and cosmic radiation. Recently scientists have discovered that the solar radiation during low sun spot activity is actually three times higher than previously thought. So if we have a warming bedrock coupled with increased radiation, the net result should be a loss of ice mass in Greenland and the Antarctic. When you consider the data that indicates the surface temperatures in the Arctic, including Greenland, did not increase significantly between 1950 and 2000, then one can hardly attribute the melting to be the result of man-made CO2 in the atmosphere. -
Frank2396 at 05:10 AM on 3 May 2010What causes Arctic amplification?
This Nature paper and your summary make the mistake of confusing a strong statistical correlation between sea ice coverage (shown in FIgure 2) and temperature with evidence for CAUSATION. The correlation could occur: a) because reduced sea ice increases temperature (the author's hypothesis), b) because increased temperature reduces sea ice (a previous hypothesis), or c) because both phenomena move in parallel in response to a third phenomena. (Nature never should have allowed this paper to be published without a clearer discussion of correlation and causation. This paper provides relatively little evidence for mechanism a) and never formally considers the other logical alternatives. The author's main evidence is that warming is greatest at the surface. Unfortunately, surface warming is a feature of the latest data (ERA-Interim) and wasn't present in earlier reanalyses (ERA-40). Clearly, our understanding of changing Arctic temperature with altitude is limited. The authors provide data that show that trends in cloud cover and humidity do not correlate with trends in temperature, suggesting these factors aren't responsible for temperature trends. No mechanism by which sea ice controls temperature is adequately discussed. Is there any evidence that changes in Arctic sea ice are not likely to be the direct cause of changes in temperature? Absolutely! First, the temperature increase is smallest in the summer months, when sea ice has been diminishing at 5.9% per decade, and largest in the winter months, when sea ice has been diminishing at a rate of 2.6% per decade. Second, during the winter, changes in sea ice coverage are restricted to the small area of the Arctic Ocean north of Scandinavia (at about 75 degN) that remains ice free (due to the Gulf Stream). However, the greatest warming is observed thousands of kilometers away at 85-90 degN. If the author's hypothesis is correct, additional energy must be obtained from unfrozen ocean in this region and somehow must travel thousands of kilometers to the north without leaving the surface. Unfortunately, the author's data has been averaged over all longitudes, so there is no evidence to support or contradict this mechanism. How do the authors explain the fact that changes in sea ice have minimal effect on surface temperatures in the summer? This is where the authors show the greatest confusion about cause-and-effect. They cite other sources saying that the trend towards warmer summer temperature is negated by energy loss from the air to the ice and/or ocean. This is mechanism b), not mechanism a). Before one can have increased energy transfer from the air to ice or ocean, one either needs warmer air to begin with, more ice, or a colder ocean. None of these phenomena exist: The author's data shows that: summer air temperature is only marginally warmer (much less than the +2 degC/decade observed in other seasons) and that sea ice is down. With less sea ice, a dramatic increase in albedo and increased humidity in the air, the ocean is unlikely to be colder. What does all this say about "Polar Amplification"? In the introduction, the authors tell us that: "It is widely accepted that changes in the surface albedo associated with melting snow and ice enhance warming in the Arctic, but other processes may contribute." Changes in albedo are greatest and most important in the summer (when the sun is shining), but warming is greatest in the non-summer months. From the information present in this paper, it should be absolutely clear that popular hypotheses do not provide satisfying explanations for the current (limited) data. A more satisfying explanation for "Arctic Amplification" might be constructed by remembering that the polar regions radiate far more energy into space than they receive from the sun (and none in winter). Therefore their temperature depends more on energy imported from other areas of the planet than anywhere else. Arctic temperature is least dependent on imported energy from other areas of the planet during the summer, when insolation is greatest. Temperature increase is least in the summer when the most dramatic changes in sea ice have been observed, so hypotheses a) and b) are relatively unattractive despite the strong statistical correlation between the two phenomena. Increased import of energy (Mechanism c.) provides the most satisfying explanation for the parallel reductions in sea ice and increases in temperature and water vapor. Unfortunately for alarmists, it suggests that a self-perpetuating cycle of positive feedbacks within the Arctic is not going to lead to climatic disaster. -
Berényi Péter at 04:54 AM on 3 May 2010Why are there fewer weather stations and what's the effect?
#30 Marcel Bökstedt at 19:09 PM on 1 May, 2010 It would be interesting to compare the trends of A and B through the whole interval Trends for the entire 40 years long interval are: set A: 0.0223 °C/year set B: 0.0322 °C/year set A+B: 0.0272 °C/year Your prediction is confirmed on these sets. However, if the last twenty years of set B is dropped from the analysis, the trend becomes 0.0342 °C/year. That is, overall trend is increased twofold by dropping stations at midpoint with large initial trends. It is a serious bias. If the many stations actually dropped from GHCN in 1990 have warming trend larger than average indeed prior to this date as Tamino claims, GHCN (and GISTEMP) does suffer from this bias. -
greenhousegaseous at 01:23 AM on 3 May 2010Skeptical Science talk at University of Qld on May 7
Give 'en hell, John! No, wait... They are gonna get that on their own. Any chance you could send the slide show to greenman3610 at YouTube? http://www.youtube.com/user/greenman3610#p/u He has a pleasant voice, a wicked sense of humor, and a solid following for his "Climate Crock of the Week" vid series. I bet he would consider how to build one based on your presentation, since you are the single-best debunker we have. Best of luck!Response: In some sense, Greenman already has done a video on my presentation - he recently did a video looking at the evidence for man-made global warming. One of the starting points for this was the empirical evidence that humans are causing global warming which is also the starting point of my talk. -
Alexandre at 01:21 AM on 3 May 2010What causes Arctic amplification?
The polar amplification is something predicted in very early studies. Hansen 1981 mentions it, and even Arrhenius 1896 predicted it. Hansen mentions a "greater atmospheric stability" on the poles, which would also be a contributing factor. Can someone help me understand what this is? -
JoeTheScientist at 00:27 AM on 3 May 2010Tracking the energy from global warming
I have two possible solutions for the missing energy. The first could account for a substantial portion of the gap, the second... not so much. Based on the Global Net Energy Budget graph, the missing energy over 5 years is about 11 quadrillion kW-hrs. First: If all of this were absorbed into permafrost-bearing regions, it amounts to 490 kW-hr/m2. To absorb all of this energy difference requires melting 5.3 metric tons of ice per m2, or a depth of 17.6 meters of permafrost melted per square meter (30% ice content). While I have no idea if melting permafrost could realistically account for ALL of the missing energy (plausible depth melted, actual ice content/m3), it is plausible that more than several meters of permafrost have melted due to rising temperatures, thus accounting for a substantial fraction of the missing energy. A possible counterargument: Why would this energy sink suddenly show up over the last 5 years rather than gradually, tracking the ups and downs of temperature change? Well, global warming took a powder from the 1940s to early 70s, remaining essentially flat, and began rising after about 1974. That means, ASSUMING that permafrost region temperature paralleled global temperature in direction, permafrost would have been roughly stable from 194X through the late 1970s. It is only after temperature began rising that permafrost would have begun to melt. There would be a substantial lag in the initiation of permafrost melt, since the temperature change would have to propagate to the bottom-most layer of the permafrost, as much as 1000 meters deep, which would take years. Additionally the rate of energy transfer into the permafrost, and therefore melting rate at depth, would depend on the temperature difference, which initially was small, increasing as temperatures rose in the north polar regions, meaning the greatest melting rate is in the more recent years. Finally, given the imprecision inherent in calculating the values going into the above graph, it is plausible that the graph is not precisely correct and that the actual "energy gap" in reality extends back farther to earlier years. Second: It is documented that the mass of plant life is increasing in high latitude areas as trees and shrubs move northward. Also one could ask whether biomass is increasing globally due to fertilizing effect of CO2 in the atmosphere. Addition of biomass in permafrost regions-only would require 242 pounds of dry biomass added per square meter, clearly implausible, but nevertheless increased polar biomass could account for some small fraction of this energy gap (say, 5%?). World wide, the biomass increase to absorb all the energy gap would have to be 11 lbs dry/sq meter, which also seems unlikely, but again a global increase in biomass could account for a fraction of the energy gap. (I didn't say I was a climate scientist!) -
Craig Allen at 23:29 PM on 2 May 2010What causes Arctic amplification?
Like Tony O, I also am surprised that this is not already understood. What do outputs from the current crop of general circulation models suggest regarding this? -
Andrew Mclaren at 23:00 PM on 2 May 2010What causes Arctic amplification?
What I meant above re: the angle of incoming IR at High Latitudes is specific to the GH effect, of course being indirect radiation it means lower surface temps to begin with! I am wondering if the greater distance that the IR passes through up there might have some measurable effect in anomalies in the upper troposphere at high lats for instance. -
Andrew Mclaren at 22:39 PM on 2 May 2010What causes Arctic amplification?
This is very informative, although I had the notion that an amplification of the Greenhouse Effect itself was in play at the higher latitudes. Would the more oblique angle of incoming IR, having to pass through a greater distance of atmosphere, have anything to do with the higher temperature anomalies in the Arctic as well? Among other factors cited of course. -
Ken Lambert at 22:27 PM on 2 May 2010Tracking the energy from global warming
Chris #100 I never said you should 'curve fit' only the last 7-8 years of 'noisy data' - why not curve fit your whole graph - since 1993; which is 17 years of noisy data?? Is that long enough to produce a valid result? The point is that sea level rise should be a lagging measure of OHC - the integral of the energy flux imbalances - so therefore if the sea level rise starts to flatten in the last 7 years - it confirms the 'lack of warming' trend discussed in Dr Trenberth's paper and other OHC analyses. -
mspelto at 21:24 PM on 2 May 2010What causes Arctic amplification?
I reviewed a paper that I find easier to digest on this topic from last year by Serreze and others (2009) The case is quite strong here that recently it is the increased thermal exchange between the open water and the atmosphere that is amplifying the warming seasonally. Why is the process not well understood? We do not have many surface stations in the Arctic Basin that allowed calibrating of detailed energy balance models. Second the extent of open water is a new characteristic. -
chris at 21:17 PM on 2 May 2010Tracking the energy from global warming
Ken Lambert at 20:26 PM on 2 May, 2010 There's nothing to "settle" Ken. Why would one want to "curve fit" 8 years of noisy data? To what purpose exactly? Incidentally, why don't you be a little more explicit about how you came up with your rate of 1.7 mm.yr-1 for the Jason data? Let's simply state what we know: (i) If we feel like doing a linear regression of the Jason data, one may as well use the whole set. This gives a trend of 2.3 mm.yr-1. This is easily determined by downloading the Jason data from the site I linked to in my post #76 (ii) The Jason data covers a very small temporal period. If one regresses the full satellite data set, Jason data included, the Jason data is consistent with a continuing sea level rise of around 3.2 mm.yr-1. We can do this analysis ourselves (I've linked to the data in my post #76). The analysis has also been published several times; e.g. by: a) Beckley, B. D. et al. (2007) [*] who determine that the sea level trend is 3.36 mm.yr-1"We obtain a global rate of 3.36 ± 0.41 mm/yr over the 14 year period from 1993 to 2007."
(b) Cazenave and Llovel (2010) who get ~ 3.4 mm.yr-1[**]"Accounting for the small correction of −0.3 mm year−1 due to global deformation of ocean basins in response to GIA (Peltier 2009), we thus get a rate of global mean sea level rise of 3.4 ± 0.4 mm year−1 over 1993–2008."
(iii) You're mistaken about Domingues et al. 2008 who's analysis is barely relevant to the issue we're discussing. Their value you quoted is for sea level rise during the period 1961-2003. Since Domingues's analysis indicates virtually zero sea level rise between ~1960 - ~ 1980 it's not surprising that the net sea level rise over the 42 year period is biased low due to the 20 year contribution from a virtually zero sea level rise. Since this is stated in the abstract, I'm surprised you didn't notice this rather obvious point (see also their Figure 1):"We add our observational estimate of upper-ocean thermal expansion to other contributions to sea-level rise and find that the sum of contributions from 1961 to 2003 is about 1.56 +/-0.4mmyr-1, in good agreement with our updated estimate of near-global mean sea-level rise (using techniques established in earlier studies6,7) of 1.66 +/-0.2mmyr-1."
(iv) overall the data (let's include your Domingues paper too) support the conclusions that sea level rise has accelerated in recent decades; the trend of the satellite era is around 3.2 mm.yr-1; the measured sea level rise is overlaid with stochastic variation that confounds meaningful analysis of trends during short periods; recent years may have seen an increase in the mass (land ice melt) component of sea level rise relative to the thermal component; there was an apparent slow down in the rate of sea level rise during a period 2006-2008 (especially apparent in the Cazenave and Llovel, 2010 data; see their Figure 2), but the sea levels seem to have "caught up" with the long term trend.... [*] Beckley, B. D. et al. (2007) A reassessment of global and regional mean sea level trends from TOPEX and Jason-1 altimetry based on revised reference frame and orbits Geophys. Res. Lett., 34, L14608 link to abstract [**] A. Cazenave and W. Llovel (2010) Contemporary Sea Level Rise Annu. Rev. Mar. Sci. 2, 145–73 link to abstract
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