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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 -
Ken Lambert at 20:26 PM on 2 May 2010Tracking the energy from global warming
Chris #97,98 You have the raw data - why don't you settle this by doing a curve fit - least squares should do so that we can see the continuous trends instead of picking average end points and drawing straight lines. Before you do so - here are some comparisons: The CSIRO paper by Domingues et al..comes up with a global average sea level rise of 1.6+/-0.2mm (published 2008) viz: http://www.nature.com/nature/journal/v453/n7198/abs/nature07080.html Dr Trenberth uses an ‘observed’ number of 2.5mm in his energy budget calculations made up of components with wide error bars eg. 0.8 +/-0.8mm. Both the above are well below the average 3.2mm of Chris’ graph. The CSIRO quotes the satellite sea level figures with error bars of +/-5mm. -
HumanityRules at 17:03 PM on 2 May 2010What causes Arctic amplification?
3.Steve L I don't get it either. Most of it seems counter-intuitive to my simple mind! The paper may be useful for ruling out some possible causes but does it do anything more than show an apparent relationship for one decade between sea ice and temperature, where is the cause and effect? Lupkes, C., T. Vihma, E. Jakobson, G. Konig-Langlo, and A. Tetzlaff (2010), Meteorological observations from ship cruises during summer to the central Arctic: A comparison with reanalysis data,Geophys. Res. Lett., doi:10.1029/2010GL042724, in press. This paper in press at GRL questions the accuracy of the ERA reanalysis compared to some ship based observations. -
Steve L at 15:05 PM on 2 May 2010What causes Arctic amplification?
I'm afraid I don't really get it. As usual I'm commenting before reading the full paper. But I did scan it and read this: "The interaction is undoubtedly two-way because warmer upper-ocean temperatures will further enhance sea ice loss." I think it's nice that Screen & Simmonds find evidence against the amplification resulting from upper atmospheric effects. I don't really know how they can focus on diminishing sea ice, though. Doesn't diminishing sea ice rely on Arctic amplification too? The abstract includes changes to ocean circulation in its list of underlying causes of Arctic amplification, and a quick perusal doesn't show me how the patterns they observed are more consistent with sea ice loss than with oceanic currents. Oh well, the paper is short enough -- maybe I'll read it tomorrow. -
Jeff Freymueller at 14:16 PM on 2 May 2010What causes Arctic amplification?
That's interesting. Here in Alaska the pattern of modest summer warming and significant winter warming applies even along much of the Pacific coast, where sea ice is not found. So perhaps the impact of sea ice changes extend out into the sub-Arctic as well. -
Tony O at 11:00 AM on 2 May 2010What causes Arctic amplification?
Given the accuracy of the predictions I would have thought that the process of Arctic Amplification was well understood. Then again the climate is so very complex that further study is always a good idea. -
suibhne at 08:29 AM on 2 May 2010Where is global warming going?
doug_bostrom I don't believe in the necessity of the notion of radiative equilibrium? We will ignore for the moment the fact that radiant energy can be transformed into other energy forms. If the Earth gains more radiation than it loses, its temperature will increase very slowly, see post 55. Likewise if the Earth loses more radiation than it gains, its temperature will decrease slowly. -
Tom Dayton at 08:27 AM on 2 May 2010CO2 effect is saturated
qball17, please refrain from nitpicking, and refrain from using over-the-top terms such as "ridiculous." You might also read more carefully, and when something doesn't make sense, consider the hypothesis that you might not be parsing it correctly; the title is "Is the CO2 Effect Saturated?," which to most readers parses correctly as "Is the CO2-Effect Saturated?" As for Scafetta, scroll down to the link to his paper in this post: It’s the sun. -
Tom Dayton at 08:19 AM on 2 May 2010CO2 lags temperature
qball17, positive feedbacks need not run away, as you can see for yourself in a spreadsheet by following my instructions in my comment on another thread. -
Doug Bostrom at 04:36 AM on 2 May 2010Where is global warming going?
Suibhne, you understand that Earth must lose energy somehow and that it appears it does so by radiative emissions but at the same time you don't believe in the notion of radiative equilibrium? Surely you'll want to qualify that remark? If the Earth is not shedding energy roughly as fast as it gains energy, surely we would expect some change in temperature here at the surface? -
pdjakow at 02:38 AM on 2 May 2010What would happen if the sun fell to Maunder Minimum levels?
@Berényi Péter "Unfortunately GHCN is dominated by USHCN stations. There is no legitimate reason it should be this way. Except it was created in America, by Americans, for Amaricans perhaps. Rather silly explanation." So what? Global anomalies are gridded. First you must calculate anomalies for each station. Then put anomalies on grid. You can also run ccc-gistemp: http://clearclimatecode.org/ You can play with the code, you can play with settings. ccc results and my results calculated on CRU database much differ from yours. And how is it possible that your anomalies are almost always below zero? What is your base period? -
chris at 01:18 AM on 2 May 2010Tracking the energy from global warming
Ken's insinuation of an offset in the Jason satellite altimetry data relative to the Topex/Poseidon altimetry data is interesting, especially since it's rather obvious by inspection of the sea level graphs (see my post #76) and the raw data (see link in my post #76) that there isn't an offset. It's worth looking at the methods by which the Topex/Poseidon and Jason satellite altimetry data was merged into a continuous record of sea level rise [***]. This also helps us to understand that an offset of the sort that Ken is hunting for is both methodologically unlikely, and also doesn't in reality, exist. Three things were done to ensure a relatively "seamless" transition: (ONE) In the transition period (15 January through 15 August 2002), the Jason and Topex/Poseidon satellites flew in formation along the same ground-track, separated in time by only about 70 seconds. Thus they collected virtually identical data for a 6 month period, and this was used to intercalibrate the altimeters and verify that the data were correctly merged in the transition period. (TWO) Although Topex data is often not presented after 2002, data was collected from Topex (the Topex B altimeter) at least through 2004. The Topex B data match with the combined Topax A/B set and with the Jason altimeter set. (THREE) During the Topex and Jason missions the satellite data is continually calibrated against the sea-level tide guage sea level measures. While tide guage measures don't provide an absolue measure of global sea level, they are effective in identifying any step changes (of the sort that you infer from your regressions). There aren't any in the Topex-Jason transition period. ---------------------------- [***] Beckley, B. D. et al. (2004) Towards a seamless transition from TOPEX/POSEIDON to Jason-1 Marine Geodesy, 27, 373-389 link to abstract E. W. Leuliette et al. (2004) Calibration of TOPEX/Poseidon and Jason altimeter data to construct a continuous record of mean sea level change Marine Geodesy 27, 79 — 94 manuscript available here 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 -
Tom Dayton at 01:12 AM on 2 May 2010Common graphical tricks and the Medieval Warm Period
alphaomega, the breadth of your comments makes me think you would benefit from and enjoy reading the overview by cce titled The Global Warming Debate. I suggest you read that before diving into the details that are in the following links. alphaomega wrote the following italicized and quoted things. For each, I've responded by linking to the appropriate post here on the Skeptical Science site. alphaomega, if you want to discuss any of those topics, those threads are the appropriate places to do so. Not on this thread, where your comments likely will be deleted for being off topic. "Dr Jones admitted in a recent BBC interview that there has been a slight cooling since 2002 and statically not significant warming since 1995." See Phil Jones says no global warming since 1995. Also see It’s cooling. "So we are on a current temperature downturn and the sun is still quiet. Is it actually possible that we might return to Maunder minimum terrritory instead?" See We’re heading into an ice age. "I do not think that AGW supporters or sceptics really know what will happen next to global temperatures." See Models are unreliable. "There may be a week warming signal caused by CO2 but natural variations in climate have the ability to overpower such a signal." See Models are unreliable. Also see CO2 is not the only driver of climate. And then CO2 effect is weak. "It is worth while reading the recent interview with Dr. Fred Goldbereg." (This one is not a post on Skeptical Science.) Goldberg is not a climatologist. His expertise is in welding. -
chris at 00:47 AM on 2 May 2010Tracking the energy from global warming
Ken Lambert at 21:12 PM on 1 May, 2010 Ken, am I right in thinking this is what you've done: a. taken 7 years of the Jason data (2003-2010?; did you use the raw archived data or eyeball the plot in my post #76?)). b. done a regression and determined the slope (you've chosen a subset that apparently gives you 1.7 mm.yr-1; if you use the full Jason data set available from the link in my post #76, the linear regression is 2.3 mm.yr-1). c. used the regression fit and extrapolated this back to 2002 (+12 mm) and forward to 2010 (+26). Is that what you did? Perhaps you could clarify. Whatever, I hope you would recognise that that's a bogus analysis. One can't use a regresssion, and then assert that particular points on the regression (e.g. the start or end points) are the data. The data are shown in my post #76, and the Jason data clearly doesn't start at +12 mm (nor does it end at +26 mm). There clearly isn't an offset with respect to the Topex data. That's also apparent by inspection of the other data sets (with/without seasonal adjustment; with/without reverse barometer correction) available from the link in my post #76. -
alphaomega at 00:01 AM on 2 May 2010Common graphical tricks and the Medieval Warm Period
SNRatio wrote 30 April "With ca 0.15 degC warming/decade, it will just take a few decades for us to leave MWP territory altogether." Dr Jones admitted in a recent BBC interview that there has been a slight cooling since 2002 and statically not significant warming since 1995 (I seem to recall). So we are on a current temperature downturn and the sun is still quiet. Is it actually possible that we might return to Maunder minimum terrritory instead? As an interested retired businessman I read both sides of the arguments and frankly I do not think that AGW supporters or sceptics really know what will happen next to global temperatures. I must admit I tend to lean towards the views held by such individuals as Dr Roy Spencer and Professor Lindzen that there may be a week warming signal caused by CO2 but natural variations in climate have the ability to overpower such a signal. For those believing that CO2 has this strong influence on global temperatures it is worth while reading the recent interview with Dr. Fred Goldbereg in People's Daily. http://english.people.com.cn/90001/90777/90853/6959757.html Frankly there seems to be a long way to go before the climate science community know enough to exhort us to pull up the wallet and deliver billions of dollars to "saving the World". Just think of the AGW understanding of the behaviour of clouds and the lack of modelling of this behaviour in current climate models. -
kdkd at 23:07 PM on 1 May 2010Tracking the energy from global warming
Ken #94I get two distinct linear trend lines from the sea level graph.
I think that's your imagination but would stand corrected if you demonstrated otherwise objectively. However my experience of graphs that look like that is that there's generally no significant difference between the regression slope at different points of the time series - the internal variability of the system is just too high. -
Ken Lambert at 21:29 PM on 1 May 2010Tracking the energy from global warming
Sphaerica #93 From what I have read, lakes of water have been discovered under the ice sheet trapped between it and the bedrock. I believe that at these extreme pressures ice can transition to supercooled water. If that pressure was removed by leakage, the supercooled water would change back to ice at well below zero temperatures. On the other hand, Ice is also a very good insulator, so across its depth, it could sustain a temperature differential. How this would work with an under ice volcano or a geothermal heat source would be interesting. -
Ken Lambert at 21:12 PM on 1 May 2010Tracking the energy from global warming
Riccardo #91 I get two distinct linear trend lines rom the sea level graph. Topex from about -24mm up to +6mm over about 9 years giving about 3.3mm/year; and Jason from about +12 to +26mm over 7 years giving about 1.7mm/year from about 2002-03 onward. This seems to indicate about a +6mm jump in the 2002-03 transition period. On these very roughly cyclical charts it seems odd that the mid point of the end of Topex would match up with the low point of the Jason plot at the transition. Would also like to know if the IBP corrected global charts are much different from this non-corrected chart. -
qball17 at 20:41 PM on 1 May 2010CO2 effect is saturated
you should have a look at the following link and see what you think.. http://miskolczi.webs.com/Answers_to_some_criticism.htm it also has a link to his 2004 paper which people don't look at, that is why they get confused and see his paper as making too many assumptions etc.. its because 2007 paper is the sequel to his 2004 paper where he defines many of his terms and comes up with the science behind the theory -
qball17 at 19:18 PM on 1 May 2010CO2 effect is saturated
and another thing.. he did publish it in hungary. Dr. Miskolczi first published his work in the Quarterly Journal of the Hungarian Meteorological Services in 2004, Volume 108, No 4. He published further statistical proof in the same Journal in 2007, Volume 111, No. 1. In the 5 years since he first published his results, not one peer review has come back disproving his theory, or his Constant. To date, not one scientist has come forward to disprove Miskolczi’s theory that the Earth’s climate is at equilibrium, and that Carbon Dioxide cannot be released in amounts great enough to upset that equilibrium. -
qball17 at 19:16 PM on 1 May 2010CO2 lags temperature
hang on a sec.. they claim that temperature drives CO2 levels, but then the rising C02 drives the temperature even further... then why is it that we aren't all living in 10000 degree temperatures? oh thats right i almost forgot.... the earth has a saturated greenhouse effect... think about it.. the earth has to have a saturation point -
Marcel Bökstedt at 19:09 PM on 1 May 2010Why are there fewer weather stations and what's the effect?
Berényi Péter> Actually, I don't find your result on the populations A and B very surprising. If we suppose that these stations have some natural variations, the elements of group B will at the time +20 years be more likely to be in a state of positive natural variation than the elements of group A. So when this natural variation on average falls back to normal (in the period between +20 and +40), this will give a negative contribution to the trend. It would be interesting to compare the trends of A and B through the whole interval (not just for the last 20 years). My prediction is that then the trend for B would be equal to or slightly more positive than the trend for group A. I'm sure that you can do this computer experiment with a few clicks, now that you have enetered all the data? But I absolutely agree with you that we should try to get as much data as possible. -
qball17 at 19:08 PM on 1 May 2010CO2 effect is saturated
and by the way.. the title of this topic is ridiculous.. its not the "saturated Co2 effect", its the "saturated GREENHOUSE effect".. we all know that we can increase the concentration of CO2.. what about the work from Dr. Nicola Scafetta?
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