‘Iris Effect’ Reduces Climate Sensitivity

Published May 29, 2015

Climate Change Weekly #174

A new paper by researchers Thorsten Mauritsen and Bjorn Stevens in Nature Geoscience lends credence to climate scientist Richard Lindzen’s speculation changes in cloud cover in the tropics in response to surface warming could act as a natural infrared iris, allowing increased infrared radiation to escape back into space, a kind of natural release valve to moderate temperatures.

In 2001, when Lindzen and his colleagues released their paper, it was largely dismissed, without any substantive analysis or further study, and deemed discredited by the climate alarmists who dominate the peer-review process and the media. As Judith Curry notes, pressure from the climate alarm industry meant Lindzen’s theory essentially languished until Mauritsen and Stevens’ paper. Curry quotes Andrew Dessler:

“By 2006, when I submitted an analysis of tropospheric water vapor that investigated whether there was an iris in that, one of the reviewers pointedly questioned why anyone was still working on this issue. I subsequently withdrew the paper. Nevertheless, just because Lindzen et al. did not convincingly demonstrate their case does not mean the iris hypothesis is wrong.”

Curry summarizes,

So the “consensus enforcers” found it necessary to “discredit” the iris hypothesis, and by extension Lindzen himself, since the reduced sensitivity threatened the “consensus.” You can see how this pernicious behavior discouraged scientists from investigating the iris hypothesis (I can only imagine how a grant proposal to investigate the iris hypothesis would have fared in peer review).

The observational record suggests climate sensitivity is lower than model predictions and indicates climate models underestimate changes in the water cycle. Those observations opened the door for Mauritsen and Stevens to investigate the possible existence of important feedbacks like the iris effect.

Running multiple iterations of the ECHAM6 general circulation climate model developed by Germany’s Max Planck Institute, with a mathematical representation of the iris effect, Mauritsen and Stevens found the “inclusion of such an effect in a climate model moves the simulated responses of both temperature and the hydrological cycle to rising atmospheric greenhouse gas concentrations closer to observations.”

In other words, a widely used climate model, modified to account for Lindzen’s iris effect, better reflects measured temperatures and changes in the water cycle than do climate models not accounting for the iris effect.

— H. Sterling Burnett

SOURCES: Nature Geoscience and Climate Etc.


CIA closes climate branch … Freeman Dyson’s biography shores up skeptic legacy … Climate policy models are useless … Nature, not humans, control greenhouse gases … Battling climate change requires expanded nuclear power


In recent months, the Obama administration has hyped purported threats posed by climate change to national security and military operations. Despite this, the CIA is shutting down its climate change program known as Medea. Medea allowed select civilian scientists access to classified data – such as ocean temperature and tidal readings gathered by Navy submarines and topography data collected by spy satellites – in an effort to glean insights about how global warming could create security threats around the world. Medea was launched in 1992 during the George H.W. Bush administration, shut down during President George W. Bush’s term, and re-launched under the Obama administration in 2010 along with a new CIA office, the Center for Climate Change.

Critics inside and outside the agency questioned whether the CIA should be tasked with climate change analysis responsibilities. According to Mother Jones, Rolf Mowatt-Larssen, a 23-year veteran of the CIA, said, “In my judgment, the CIA is not the best lead agency for the issue; the agency’s ‘in-box’ is already overflowing with today’s threats and challenges.” Congressional Republicans led by Sen. John Barrasso (WY) also questioned the wisdom of committing the CIA’s scarce resources to fighting global warming. In 2014, Barrasso said the CIA “should be focused on monitoring terrorists in caves, not polar bears on icebergs.”

The Obama administration closed the CIA Center for Climate Change in 2012. With Medea’s closure, the CIA’s climate mission seems to have wound down.

SOURCE: Mother Jones


In his new biography Dreams of Earth and Sky, multi-award winning physicist Freeman Dyson reinforces the fact he is a climate change skeptic. He writes,

Human actions have very large effects on the ecology, which have nothing to do with the climate. Carbon dioxide is what we’re producing in big quantities and putting into the atmosphere. This happens to be a very good fertilizer for all kinds of vegetation, good for wildlife, good for agricultural production, so it has many benefits. And this is something you have together with the climate effects, which are much less certain, so it’s a question of drawing a balance. I’m just saying I don’t understand it and neither does anybody else. I’m skeptical because I don’t think the science is at all clear, and unfortunately a lot of the experts really believe they understand it, and maybe have the wrong answer.

SOURCE: Watts Up With That


In a forthcoming research paper, MIT economist Robert Pindyck argues climate models being used to shape policy responses to climate change “have flaws that make them close to useless as tools for policy analysis.” Integrated Assessment Models (IAMs) have a limited understanding of the climate’s sensitivity to greenhouse gas concentrations and the “relationship between an increase in temperature and GDP.”

Because model predictions of increased numbers, duration, or intensity of extreme weather events have failed to materialize, the models should not be used to calculate the social costs of carbon (SCC) on the economy, or the benefits and costs of policy responses like carbon taxes or cap-and-trade schemes on economic growth.

Michael Bastasch reports the experts who developed the SCC calculations for the Obama administration admitted, “[t]here is currently a limited amount of research linking climate impacts to economic damages, which makes this exercise even more difficult.” Pindyck concludes, “Claiming that IAMs can be used to evaluate policies and determine the SCC is misleading to say the least, and gives economics a bad name.”

SOURCE: The Daily Caller


A long-term study published in the Proceedings of the National Academy of Sciences shows nature outweighs human contributions to climate change. According to the study, decomposition of dead plant and animal material by soil microorganisms generates 10 times more carbon dioxide and methane emissions than human activities annually. The study reports maintaining a healthy and diverse soil community can reduce the amount of greenhouse gases entering the atmosphere each year. The study – by researchers at the Yale School of Forestry & Environmental Studies, University of Helsinki, Institute of Microbiology of the Academy of Sciences in the Czech Republic, and University of New Hampshire – shows healthy and diverse soil communities limit the damaging effects of warmer climate while organisms like insects and worms, feeding on the greenhouse gas-generating microorganisms, reduce overall emissions into the atmosphere. The researchers found, “In the same way that Yellowstone’s wolves regulate plant diversity by controlling the number of grazing elk … small animals – such as insects and worms – can play a similar regulatory role in soil ecosystems by feeding on the microbes that can trigger increased carbon emissions.”

SOURCE: Eureka Alerts


A liberal environmental think tank, The Breakthrough Institute, is breaking with many radical environmental organizations by supporting the expansion of nuclear power to fight climate change. Breakthrough rejects forced population control and argues current and foreseeable renewable power technologies cannot meet the power needs of present or future generations. Its fact sheet on nuclear power argues:

Most people on the planet actually need to consume more energy, not less. Energy consumption is highly correlated with better health outcomes, longer life spans, and higher living standards. But the basic math of global development and global warming is unforgiving. If we are going to meet the needs of a growing global population while keeping global warming in check, we will need technologies that can produce enormous amounts of energy without emitting carbon.

Whether we in fact need to reduce carbon dioxide emissions is open for debate, but if we do, Breakthrough has the right perspective. Over the next 40 years, if the world is to produce the vast amounts of energy needed for growing, wealthier populations while reducing carbon dioxide emissions, an enormous expansion of nuclear power will be necessary.

SOURCE: The Breakthrough Institute

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