Dr. Roy Spencer presents the latest measurements of lower troposphere temperature as measured by two sets of satellites. See his post here. He presents a graph showing measured temperatures versus model predictions.

You can see that actual global temperatures have flattened out since about 1998. The “spaghetti” on the graph represents predictions of 44 models and the black line is the average of model predictions.

Spencer presents three possible explanations for the divergence:

“1) the real climate system is not as sensitive to increasing CO₂ as the models are programmed to be.” (His preferred explanation).

“2) the extra surface heating from more CO₂ has been diluted more than expected by increased mixing with cooler, deeper ocean waters (Trenberth’s explanation)”

The oceans have a high heat capacity and can absorb great quantities of heat. But have they? The subject is controversial. Anthony Watts discusses the problem here. He notes a recent study which says that between 1955 and 2010, the temperature of the global ocean, between the surface and a depth of 2,000 meters increased in temperature by 0.09 C. That’s not much and Watts wonders if we can even measure to that precision.

“3) increased manmade aerosol pollution is causing a cooling influence, partly mitigating the manmade CO₂ warming.”

However, a 2007 satellite-based NASA study shows that aerosols have been decreasing steadily since 1992. In particular, sulfate aerosols have been greatly decreasing since establishment of the 1970 Clean Air Act in the U.S. and similar measures in Europe.

Explanations #2 and #3 seem to have problems. That leaves #1: the climate is not very sensitive to carbon dioxide and is much less sensitive than models assume. The forcing effect of carbon dioxide, if any, is apparently easily overcome by stronger natural forces.

If Spencer’s first explanation is correct, the political war on fossil fuel emissions is futile and will have little or no effect on global temperatures, but that war will cost us dearly by raising energy prices and making our electric grid less reliable.

See also:

Global warming theory fails again

Failure of the Anthropogenic Global Warming Hypothesis

 

Dr. James Hansen, chief global warming alarmist and head of NASA’s Goddard Institute for Space Studies has a new paper in Environmental Research Letters wherein he says that burning coal has caused the hiatus in global temperature rise for the past 15 to 20 years (see here also).

Hansen attributes this to the fact that more carbon dioxide in the atmosphere stimulates plant growth, which, in turn, takes more carbon dioxide out of the atmosphere. “We suggest that the surge of fossil fuel use, mainly coal, since 2000 is a basic cause of the large increase of carbon uptake by the combined terrestrial and ocean carbon sinks. One mechanism by which fossil fuel emissions increase carbon uptake is by fertilizing the biosphere via provision of nutrients essential for tissue building, especially nitrogen, which plays a critical role in controlling net primary productivity and is limited in many ecosystems.” In Hansen’s figure 3, he notes that even though carbon dioxide emissions have been increasing, the airborne fraction of CO₂ [the ratio of observed atmospheric CO₂ increase to fossil fuel CO₂ emissions] has decreased over the past 50 years, especially after the year 2000.

That means that natural processes are compensating for increased emissions. This mechanism is noted in a report by the Center for the Study of Carbon Dioxide and Global Change in which they state: “The productivity of the planet’s terrestrial biosphere, on the whole, has been increasing with time, revealing a great greening of the Earth that extends throughout the entire globe. Satellite-based analyses of net terrestrial primary productivity reveal an increase of around 6-13% since the 1980s.”

Some scientists claim that part of the lack of temperature rise is due to the cooling aerosol effect of sulfur dioxide, also a byproduct of burning coal. Hansen rejects this and is supported by an earlier NASA paper which says that sulfur dioxide (SO₂) aerosols in the atmosphere are due mainly to increasing volcanic activity, not from burning coal.

Hansen also notes that the effect [forcing] of man-made greenhouse gas emissions has fallen below IPCC projections, despite an increase in man-made CO₂ emissions exceeding IPCC projections.

This paper is quite an admission from someone who once said, “The trains carrying coal to power plants are death trains. Coal-fired power plants are factories of death.”

Hansen’s reasoning seems somewhat circular to me. He’s saying that more carbon dioxide is creating less carbon dioxide. He is also ignoring the fact that as the globe warms (such as warming from the Little Ice Age of the 1850s), the oceans exsolve more carbon dioxide into the atmosphere. He is assuming that carbon dioxide is the major driver of global temperature, a contention for which there is no physical evidence. More likely, the “hiatus in global temperature rise for the past 15 to 20 years” has been caused by something other than carbon dioxide, such as solar cycles which overwhelm the weak warming force of carbon dioxide acting as a greenhouse gas. It is true, however, that as atmospheric carbon dioxide increased, there has been a great greening of the earth as plants respond to the aerial fertilization.

In spite of all the scary scenarios put forth by IPCC climate models, we see that modeling results are an artifact of modeling inputs; that’s a polite way of saying “garbage in – garbage out.” And perhaps Hansen is now realizing the implications of something he wrote back in 1998: “”The forcings that drive long-term climate change are not known with an accuracy sufficient to define future climate change.”

UPDATE: The New York Times reports that James Hansen will quit his NASA  job this week to become a full-time climate activist.

See also:

Failure of the Anthropogenic Global Warming Hypothesis

Global warming theory fails again

Last week there was much buzz in the media about a new paper that used fossils from sediment and ice cores to reconstruct global temperatures for the last 11,000 years.

Typical of the headlines was this one from the Arizona Daily Star: “Study: Global heat spike unique in past 11,000 yrs.” The fuss was caused by this paper: “A Reconstruction of Regional and Global Temperature for the Past 11,300 Years” by Marcott et al., published in Science.

The paper’s graph causing all the stir is shown below:

The paper’s abstract contains this sentence: “Current global temperatures of the past decade have not yet exceeded peak interglacial values but are warmer than during ~75% of the Holocene temperature history.” That alone gives the lie to the graph and to the Star’s headline.

A critique of the paper may be found at WUWT here.

Essentially Marcott et al. used Michael Mann’s hockey stick trick to co-join two data sets of very different resolutions to come up with the spike, in other words they joined apples and oranges.

That procedure blurs out the Medieval Warm Period of about 1,000 years ago even though that period was as warm or warmer than current temperatures.

In the WUWT critiques, Robert Rhode, of the Berkeley Earth Surface Temperature Study, explains the problem:

“They rely on proxy data that is widely spaced in time (median sampling interval 120 years) and in many cases may also be subject to significant dating uncertainty. These effects will both tend to blur and obscure high frequency variability. They estimate…that only 50% of the variance is preserved at 1,000-year periods. This amount of variance suppression is roughly what you would expect if the underlying annual temperature time series had been smoothed with a 400-year moving average. In essence, their reconstruction appears to tell us about past changes in climate with a resolution of about 400 years. That is more than adequate for gathering insights about millennial scale changes during the last 10,000 years, but it will completely obscure any rapid fluctuations having durations less than a few hundred years…..one should be careful in comparing recent decades to early parts of their reconstruction, as one can easily fall into the trap of comparing a single year or decade to what is essentially an average of centuries….since their methodology suppresses most of the high frequency variability, one needs to be cautious when making comparisons between their reconstruction and relatively rapid events like the global warming of the last century.”

Another point from geologist Dr. Don Easterbrook:

“Eighty percent of the source data sites were marine, so temperatures from 80% of the data set used in this paper record ocean water temperatures, not atmospheric temperatures. Thus, they may reflect temperature changes from ocean upwelling, changes in ocean currents, or any one of a number of ocean variations not related to atmospheric climates. This in itself means that the Marcott et al. temperatures are not a reliable measure of changing atmospheric climate.”

Additional comments from Dr. Judith Curry, Georgia Tech: “There doesn’t seem to be anything really new here in terms of our understanding of the Holocene.  Mike’s Nature trick seems to be now a standard practice in paleo reconstructions.  I personally don’t see how this analysis says anything convincing about climate variability on the time scale of a century.”

Interestingly, buried in the supplementary material to their paper, Marcott et al. showed the results of running their data through a computer program which used different algorithms and assumptions. This exercise produced a quite different graph from the same data:

That graph is not nearly as scary looking as the one touted in the headlines. This just goes to show that the results depend on the assumptions and methods used in the computer program: Garbage in – Garbage out. Of course, that graph would not garner headlines.

 

 

 

 

 

WUWT update post: Marcott et al claim of ‘unprecedented’ warming compared to GISP ice core data.  This update from WUWT graphically shows that the current warmth is not unprecedented as claimed.  The first sentence of Marcott et al. says, “Surface temperature reconstructions of the past 1500 years suggest that recent warming is unprecedented in that time.”  This is clearly false.  Anthony Watts superimposes the Marcott data over an earlier study of Greenland ice core data  to get this graph:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 To put things in perspective, look at the following graph, a temperature reconstruction based on ice core data.  Unlike the Marcott paper, this reconstruction shows that current temperatures are among the coolest of the last 10,000 years.  Notice also the previous periods of rapid warming (red lines on the graph).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UPDATE: April 2, 2013, Ross McKitrick explains how Marcott purposely changed the dates on proxy core to produce the uptick: http://opinion.financialpost.com/2013/04/01/were-not-screwed/

UPDATE: A simple test shows where Marcott goes wrong see here.  See a good explanation of the deception from Resilient Earth here.

Steve McIntyre deconstructs Marcott:

Marcott Mystery #1

No Uptick in Marcott Thesis

Marcott’s Zonal Reconstructions

How Marcottian Upticks Arise

The Marcott-Shakun Dating Service

Hiding the Decline: MD01-2421

 

See also:

20^th Century temperatures explained as natural recovery from Little Ice Age

More evidence that current warming is not unusual