by scientists for scientists?
big deal.

(sorry, i'm still to computer abilities challenged to know how to copy images..)
A warming pause?
Filed under:

* Climate Science
* Communicating Climate
* Instrumental Record
* skeptics

— stefan @ 6 October 2009

The blogosphere (and not only that) has been full of the “global warming is taking a break” meme lately. Although we have discussed this topic repeatedly, it is perhaps worthwhile reiterating two key points about the alleged pause here.

(1) This discussion focuses on just a short time period – starting 1998 or later – covering at most 11 years. Even under conditions of anthropogenic global warming (which would contribute a temperature rise of about 0.2 ºC over this period) a flat period or even cooling trend over such a short time span is nothing special and has happened repeatedly before (see 1987-1996). That simply is due to the fact that short-term natural variability has a similar magnitude (i.e. ~0.2 ºC) and can thus compensate for the anthropogenic effects. Of course, the warming trend keeps going up whilst natural variability just oscillates irregularly up and down, so over longer periods the warming trend wins and natural variability cancels out.

(2) It is highly questionable whether this “pause” is even real. It does show up to some extent (no cooling, but reduced 10-year warming trend) in the Hadley Center data, but it does not show in the GISS data, see Figure 1. There, the past ten 10-year trends (i.e. 1990-1999, 1991-2000 and so on) have all been between 0.17 and 0.34 ºC per decade, close to or above the expected anthropogenic trend, with the most recent one (1999-2008) equal to 0.19 ºC per decade – just as predicted by IPCC as response to anthropogenic forcing.

GISS temperature trends

Figure 1. Global temperature according to NASA GISS data since 1980. The red line shows annual data, the larger red square a preliminary value for 2009, based on January-August. The green line shows the 25-year linear trend (0.19 ºC per decade). The blue lines show the two most recent ten-year trends (0.18 ºC per decade for 1998-2007, 0.19 ºC per decade for 1999-2008) and illustrate that these recent decadal trends are entirely consistent with the long-term trend and IPCC predictions. Even the highly “cherry-picked” 11-year period starting with the warm 1998 and ending with the cold 2008 still shows a warming trend of 0.11 ºC per decade (which may surprise some lay people who tend to connect the end points, rather than include all ten data points into a proper trend calculation).

Why do these two surface temperature data sets differ over recent years? We analysed this a while ago here, and the reason is the “hole in the Arctic” in the Hadley data, just where recent warming has been greatest.

Mean temperature difference between the periods 2004-2008 and 1999-2003
Figure 2. The animated graph shows the temperature difference between the two 5-year periods 1999-2003 and 2004-2008. The largest warming has occurred over the Arctic in the past decade and is missing in the Hadley data.

If we want to relate global temperature to global forcings like greenhouse gases, we’d better not have a “hole” in our data set. That’s because global temperature follows a simple planetary heat budget, determined by the balance of what comes in and what goes out. But if data coverage is not really global, the heat budget is not closed. One would have to account for the heat flow across the boundary of the “hole”, i.e. in and out of the Arctic, and the whole thing becomes ill-determined (because we don’t know how much that is). Hence the GISS data are clearly more useful in this respect, and the supposed pause in warming turns out to be just an artifact of the “Arctic hole” in the Hadley data – we don’t even need to refer to natural variability to explain it.

Imagine you want to check whether the balance in your accounts is consistent with your income and spendings – and you find your bank accounts contain less money than you expected, so there is a puzzling shortfall. But then you realise you forgot one of your bank accounts when doing the sums – and voila, that is where the missing money is, so there is no shortfall after all. That missing bank account in the Hadley data is the Arctic – and we’ve shown that this is where the “missing warming” actually is, which is why there is no shortfall in the GISS data, and it is pointless to look for explanations for a warming pause.

It is noteworthy in this context that despite the record low in the brightness of the sun over the past three years (it’s been at its faintest since beginning of satellite measurements in the 1970s), a number of warming records have been broken during this time. March 2008 saw the warmest global land temperature of any March ever recorded in the past 130 years. June and August 2009 saw the warmest land and ocean temperatures in the Southern Hemisphere ever recorded for those months. The global ocean surface temperatures in 2009 broke all previous records for three consecutive months: June, July and August. The years 2007, 2008 and 2009 had the lowest summer Arctic sea ice cover ever recorded, and in 2008 for the first time in living memory the Northwest Passage and the Northeast Passage were simultaneously ice-free. This feat was repeated in 2009. Every single year of this century (2001-2008) has been warmer than all years of the 20th Century except 1998 (which sticks out well above the trend line due to a strong El Niño event).

The bottom line is: the observed warming over the last decade is 100% consistent with the expected anthropogenic warming trend of 0.2 ºC per decade, superimposed with short-term natural variability. It is no different in this respect from the two decades before. And with an El Niño developing in the Pacific right now, we wouldn’t be surprised if more temperature records were to be broken over the coming year or so.
http://www.realclimate.org/index.php/archi...-warming-pause/

Racial theories in Nazi Germany were also peer reviewed. By other Nazi. Global warming "science" was peer reviewed by people who already believed in all. All dissenters were excluded.

The bottom line is: the observed warming over the last decade is 100% consistent with the expected anthropogenic warming trend of 0.2 ºC per decade, superimposed with short-term natural variability. It is no different in this respect from the two decades before. And with an El Niño developing in the Pacific right now, we wouldn’t be surprised if more temperature records were to be broken over the coming year or so.

LOL. When it gets warmer the causes are man-made. When it gets cooler it is considered a "natural variation"


Priceless.

Stefan Rahmstorf
Filed under:

* Contributor Bio's

— stefan @ 6 December 2004

Stefan Rahmstorf

A physicist and oceanographer by training, Stefan Rahmstorf has moved from early work in general relativity theory to working on climate issues.

He has done research at the New Zealand Oceanographic Institute, at the Institute of Marine Science in Kiel and since 1996 at the Potsdam Institute for Climate Impact Research in Germany (in Potsdam near Berlin).

His work focuses on the role of ocean currents in climate change, past and present.

In 1999 Rahmstorf was awarded the $ 1 million Centennial Fellowship Award of the US-based James S. McDonnell foundation.

Since 2000 he teaches physics of the oceans as a professor at Potsdam University.

Rahmstorf is a member of the Advisory Council on Global Change of the German government and of the Academia Europaea. He is a lead author of the paleoclimate chapter of the 4th assessment report of the IPCC.

Professor of Physics of the Oceans, Potsdam University
Head of Earth System Analysis, PIK
Honorary Fellow of the University of Wales/Bangor
Member of the Academia Europaea
Member of the German Advisory Council on Global Change (WBGU)


and johnnybisquik ...............................................

So?

Can you tell me why it has gotten colder but no one is saying the causes for it are man-made?

Thanks

General relativity theory to climate change science.

Sounds like funding was running out in the GR biz, eh Stefan?

:lol:

Not once did I ever hear about a cooling period. All I ever heard from the scare-mongers was how the warming would get worse with each passing year.

Now that there hasn't been any warming for the last decade, they're claiming they predicted it.

Show me an article from 10 years ago that says as much and I'll believe them. Otherwise they're a bunch of liars.

its about the time when global warming became climate change, so all the bases were covered

[sarcasm]because everyone knows climate and weather is static [ /sarcasm]

many if not most did champs. when i get back from work i'll look them up.
again.
and again.
and again. i'm sure.

Cool, err I mean that is hot. We'll wait for it.

Friday you work some stupid long hours bro.

sorry. life's full you know.
http://williamcalvin.com/1990s/1998AtlanticClimate.htm

http://en.wikipedia.org/wiki/Shutdown_of_t...ine_circulation

The idea of a global cooling as the result of global warming was already proposed in the 1990s.[27] In 2003, the Office of Net Assessment at the United States Department of Defense was commissioned to produce a study on the likely and potential effects of a modern climate change, especially of a shutdown of thermohaline circulation.[28] The study, conducted under ONA head Andrew Marshall, modelled its prospective climate change on the 8.2 kiloyear event, precisely because it was the middle alternative between the Younger Dryas and the Little Ice Age. The study caused controversy in the media when it was made public in 2004.[29][30] However, scientists acknowledge that “abrupt climate change initiated by GIS melting is not a realistic scenario for the 21st century.”[31].
http://en.wikipedia.org/wiki/Global_cooling

and just about all say they expect oscillations in the global mean temperature...
phone..

but.....
What the science says...

Empirical measurements of the Earth's heat content show the planet is still accumulating heat and global warming is still happening. Surface temperatures can show short term cooling when heat is exchanged between the atmosphere and the ocean, which has a much greater heat capacity than the air.

To say we're currently experiencing global cooling overlooks one simple physical reality - the land and atmosphere are only one small fraction of the Earth's climate (albeit the part we inhabit). Global warming is by definition global. The entire planet is accumulating heat due to an energy imbalance. The atmosphere is warming. Oceans are accumulating energy. Land absorbs energy and ice absorbs heat to melt. To get the full picture on global warming, you need to view the Earth's entire heat content.

This analysis is performed in An observationally based energy balance for the Earth since 1950 (Murphy 2009) which adds up heat content from the ocean, atmosphere, land and ice. To calculate the Earth's total heat content, the authors used data of ocean heat content from the upper 700 metres. They included heat content from deeper waters down to 3000 metres depth. They computed atmospheric heat content using the surface temperature record and the heat capacity of the troposphere. Land and ice heat content (eg - the energy required to melt ice) were also included.


Figure 1: Total Earth Heat Content from 1950 (Murphy 2009). Ocean data taken from Domingues et al 2008.

A look at the Earth's total heat content clearly shows global warming has continued past 1998. So why do surface temperature records show 1998 as the hottest year on record? Figure 1 shows the heat capacity of the land and atmosphere are small compared to the ocean (the tiny brown sliver of "land + atmosphere" also includes the heat absorbed to melt ice). Hence, relatively small exchanges of heat between the atmosphere and ocean can cause significant changes in surface temperature.

In 1998, an abnormally strong El Nino caused heat transfer from the Pacific Ocean to the atmosphere. Consequently, we experienced above average surface temperatures. Conversely, the last few years have seen moderate La Nina conditions which had a cooling effect on global temperatures. And the last few months have swung back to warmer El Nino conditions. This has coincided with the warmest June-August sea surface temperatures on record. This internal variation where heat is shuffled around our climate is the reason why surface temperature is such a noisy signal.

Figure 1 also underscores just how much global warming the planet is experiencing. Since 1970, the Earth's heat content has been rising at a rate of 6 x 1021 Joules per year. In more meaningful terms, the planet has been accumulating energy at a rate of 190,260 GigaWatts. Considering a typical nuclear power plant has an output of 1 GigaWatt, imagine 190,000 nuclear power plants pouring their energy output directly into our oceans.

How do we find out what's happened from 2003 until now? Unfortunately, there is no time series (that I know of) of the planet's total heat content up to present time. However, we do have the next best thing. Global hydrographic variability patterns during 2003–2008 (Schuckmann 2009) analyses ocean temperature measurements by the Argo network, constructing a map of ocean heat content down to 2000 metres. This is significantly deeper than other recent papers that focus on upper ocean heat, only going down to 700 metres. They constructed the following time series of global ocean heat:


Figure 2: Time series of global mean heat storage (0–2000 m), measured in 108 Jm-2.

Globally, the oceans continued to accumulate heat right to the end of 2008. Over the last 5 years, the oceans have been absorbing heat at a rate of 0.77 ± 0.11 Wm−2. Combined with the results of Murphy 2009, we now see a picture of continued global warming.

How does this value compare to other estimates of energy imbalance? Hansen 2005, using ocean heat data, calculated the planet's energy imbalance around 2003 to be 0.85 Wm−2. Trenberth 2009 examined satellite measurements of incoming and outgoing radiation for the March 2000 to May 2004 period and found the planet accumulating energy at a rate of 0.9 ± 0.15 Wm−2.

All these estimates are consistent with each other. Most importantly, all find a statistically significant positive energy imbalance. The empirical data has spoken. The planet is still accumulating heat. Global warming is still happening.
http://www.skepticalscience.com/global-cooling.htm

estimates

estimates

estimates

fridays links are all cute and stuff but they still don't address Champs poignant and on the mark comments.

Not once did I ever hear about a cooling period. All I ever heard from the scare-mongers was how the warming would get worse with each passing year.

Now that there hasn't been any warming for the last decade, they're claiming they predicted it.

Show me an article from 10 years ago that says as much and I'll believe them. Otherwise they're a bunch of liars.

Try again friday. Keep searching for that needle in the haystack, Dopey.

Wiki was around in 1998? LMAO!