September 8, 2011

More Evidence That Models Continue To Show Too Much Recent Warming

In our last World Climate Report article, we detailed a recent paper that showed that climate models which fail to account for the evolution of stratospheric aerosols (that is, reflective particles in the earth’s upper atmospheric) during the past decade or two project less warming than they would have had they included the influence of stratospheric aerosols in their calculations. This means that the discrepancy between the observed warming trend during the past 10-15 years (which is near zero) and climate model projections should be even larger than it appears (and it is already quite large).

Now comes along a new paper which hints at another reason why the climate models should actually be projecting more warming than they currently do—again, meaning that the models are faring even worse than it appears.

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August 5, 2011

The Lack of Recent Warming and the State of Peer Review

Over at the Cato Institute website, WCR’s Patrick Michaels has another one of his informative Current Wisdom pieces, a place where he “reviews interesting items on global warming in the scientific literature that may not have received the media attention that they deserved, or have been misinterpreted in the popular press.” The topic this time around is the recent paper in the Proceedings of the National Academy of Sciences by Robert Kaufmann and colleagues in which they conclude that one of the primary reasons that the earth has not warmed up as advertised during the past 10 -15 years is that rapidly growing sulfur emissions from China (as a result of their increased usage of coal for power generation) have acted to offset a significant proportion of the greenhouse warming.

Pat explains why this hypothesis is, well, simply wrong.

Instead, natural variability is the primary reason, along with the possibility that the climate sensitivity (i.e., how much warming will occur as atmospheric greenhouse gas levels double) is on the low side of IPCC estimates (which range from 2.0°C – 4.5°C).

Pat also details the trials and tribulations that we encountered when trying to publish this finding several years ago.

Check out all the sordid details in the article The Current Wisdom: The Lack of Recent Warming and the State of Peer Review.




May 23, 2011

Less Cooling Means Less Warming

Filed under: Aerosols, Climate Forcings

We occasionally highlight articles from the scientific literature showing that the cooling impact of aerosol emissions from human activities has been overestimated. Such findings are important because they mean that warming from greenhouse gases has been similarly overestimated.

Climate models rely on aerosol cooling to keep warming in check—otherwise they predict far more warming to occur than has been observed. So, if aerosols produce less cooling, then this means that the climate models must compensate by producing less warming from greenhouse gases than they do presently. If they don’t, they will fail to replicate the observed temperature history.

In a paper soon to appear in Geophysical Research Letters, an M.I.T. research team led by Jason Cohen finds that by including in climate models aerosol-influencing processes that take place in urban environments, the total global-average negative forcing (i.e., cooling pressure) from aerosols is significantly less than when these urban processes are not considered—as is currently the case with all climate models.

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April 29, 2011

Shale Gas: A Climate Friendly Fossil Fuel?

A few weeks back, in our article Biggest Drop in U.S. Greenhouse Gas Emissions, we promised to take a look at the implications of a new study that calculated the impact on the earth’s greenhouse effect from the extraction and use of natural gas produced from deep underground shale beds (through a process known as hydraulic fracturing, or “fracking”). The study was conducted by a research team from Cornell University led by Dr. Robert Howarth, and its conclusions were quite surprising:

“Compared to coal, the [greenhouse gas] footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.”

The reason that this is surprising (and has a lot of people talking) is that natural gas has long been considered the most “climate friendly” of all the fossil fuels and a potential “bridge” to a low carbon future. The Howarth et al. study now threatens natural gas’s most favored status (at least among climate change-fearing types).

Over at the free market energy blog Master Resource, WCR’s Chip Knappenberger takes a look at the Howarth et al. study, as well as its many criticisms.

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April 14, 2011

Biggest Drop in U.S. Greenhouse Gas Emissions

In 2009, greenhouse gas emissions in the U.S. experienced their biggest drop since the U.S. Energy Information Administration began tracking them during the 1990-2009 timeframe.

The EIA’s latest numbers on greenhouse gas emissions can be found in their just released report “Emissions of Greenhouse Gases in the United States 2009.”

The EIA starts out with this summary:

Total U.S. anthropogenic (human-caused) greenhouse gas emissions in 2009 were 5.8 percent below the 2008 total. The decline in total emissions—from 6,983 million metric tons carbon dioxide equivalent (MMTCO2e) in 2008 to 6,576 MMTCO2e in 2009—was the largest since emissions have been tracked over the 1990-2009 time frame. It was largely the result of a 419-MMTCO2e drop in carbon dioxide (CO2) emissions (7.1 percent).

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July 15, 2010

Solar Control on Tibet’s Climate

We see many articles like the following two that show more evidence of a solar control on climate even at the regional scale.

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May 26, 2010

Solar Story Update

Filed under: Climate Forcings, Solar

We have written about the solar control on climate many times in the past, and to say the least, the debate continues to rage regarding the solar influence of Earth’s climate. IPCC has been luke warm on the subject, stating in the Technical Summary that “Solar irradiance contributions to global average radiative forcing are considerably smaller than the contribution of increases in greenhouse gases over the industrial period.” Two articles have appeared recently that provide even more evidence that variations in solar output have a profound impact on regional, hemispheric, and global climatic variations.

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February 1, 2010

What’s Happened to Global Warming?

One of the enduring pillars of the climate change issue is that the temperature of the Earth is increasing at an unprecedented rate … we’ve heard it a million times over the past few decades. However, it is well known that the temperature of the Earth has not increased over the past decade, and the lack of recent warming is now receiving serious consideration in the leading scientific journals. Two recent articles are of particular interest to us at World Climate Report.

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January 8, 2010

Is Earth’s Temperature Controlled by the Sun?

Filed under: Climate Forcings, Solar

Nicola Scafetta is an atmospheric scientist with Duke University’s highly regarded Department of Physics, and in a recent article in the Journal of Atmospheric and Solar-Terrestrial Physics, he provides an excellent introduction for us stating “Estimating the solar contribution to global mean air surface temperature change is fundamental for evaluating the anthropogenic contribution to climate change. This is regarded as one of the most important issues of our time. While some theoretical climate model studies indicate that the solar variability has little effect on climate (these studies estimate that less than 10% of the global warming observed since 1900 is due to the sun), several empirical studies suggest that large climatic variations are well synchronized with solar variations and, therefore, climate is quite sensitive to solar changes.”

No doubt about it – a considerable debate rages in the climate community about the role of the sun in controlling the temperature of the earth. There are many leading climate scientists who believe that the sun’s impact is negligible while others believe the sun’s control on earth’s temperature is substantial. Both groups publish regularly, and there is no end of empirical and theoretical evidence to support both camps. If you think the debate is over in the world of climate change, look at the literature on solar control of climate, and you will immediately conclude the debate is as lively as ever.

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November 10, 2009

Airborne Fraction of Human CO2 Emissions Constant over Time

A couple of months back, there was a discussion taking place over at Joe Romm’s ClimateProgress blog concerning a report that the earth’s ability to take-up atmospheric carbon dioxide was declining. A declining CO2 sink, of course, meant that things climatological were going to be even worse than expected, because a growing proportion of anthropogenic CO2 emissions were going to remain in the atmosphere, thus pushing the rise of CO2 concentrations and the degree of climate change higher.

At the time, an alert reader pointed out to Joe Romm that there was in fact, no indication from data and observations that a larger percentage of human CO2 emissions were ending up in the atmosphere. In fact, the data showed that the fraction of CO2 emitted into the atmospheric by human activities has remained constant for the past 40 years.

This fact runs directly counter to the idea that the earth’s natural CO2 sinks are weakening—instead it indicates that natural sinks have been expanding as anthropogenic CO2 emissions have increased. After all, in order to keep the airborne fraction of CO2 emissions constant over time, increasing anthropogenic CO2 emissions must be countered by an increasing CO2 sink.

Joe Romm was a bit dismissive (to say the least) of this line of argument.

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