Query: Lindzen and Choi find low climate sensitivity

Relevant passages:
Iris hypothesis <=SEP=> The iris hypothesis is a hypothesis proposed by Richard Lindzen et al. in 2001 that suggested increased sea surface temperature in the tropics would result in reduced cirrus clouds and thus more infrared radiation leakage from Earth 's atmosphere . His study of observed changes in cloud coverage and modeled effects on infrared radiation released to space as a result supported the hypothesis . This suggested infrared radiation leakage was hypothesized to be a negative feedback in which an initial warming would result in an overall cooling of the surface . The consensus view is that increased sea surface temperature would result in increased cirrus clouds and reduced infrared radiation leakage and therefore a positive feedback .   Other scientists subsequently tested the hypothesis . Some concluded that there was no evidence supporting the hypothesis . Others found evidence suggesting that increased sea surface temperature in the tropics did indeed reduce cirrus clouds but found that the effect was nonetheless a positive feedback rather than the negative feedback that Lindzen had hypothesized . A later 2007 study conducted by Roy Spencer et al. using updated satellite data potentially supported the iris hypothesis . In 2011 , Lindzen published a rebuttal to the main criticisms . In 2015 a paper was published which again suggested the possibility of an `` Iris Effect '' . It also proposed what it called a `` plausible physical mechanism for an iris effect . ''

Global warming controversy <=SEP=> The global warming controversy concerns the public debate over whether global warming is occurring , how much has occurred in modern times , what has caused it , what its effects will be , whether any action should be taken to curb it , and if so what that action should be . In the scientific literature , there is a strong consensus that global surface temperatures have increased in recent decades and that the trend is caused by human-induced emissions of greenhouse gases . No scientific body of national or international standing disagrees with this view , though a few organizations with members in extractive industries hold non-committal positions . Disputes over the key scientific facts of global warming are more prevalent in the media than in the scientific literature , where such issues are treated as resolved , and such disputes are more prevalent in the United States than globally .   Political and popular debate concerning the existence and cause of climate change includes the reasons for the increase seen in the instrumental temperature record , whether the warming trend exceeds normal climatic variations , and whether human activities have contributed significantly to it . Scientists have resolved these questions decisively in favour of the view that the current warming trend exists and is ongoing , that human activity is the cause , and that it is without precedent in at least 2000 years . Public disputes that also reflect scientific debate include estimates of how responsive the climate system might be to any given level of greenhouse gases ( climate sensitivity ) , how global climate change will play out at local and regional scales , and what the consequences of global warming will be .   Global warming remains an issue of widespread political debate , often split along party political lines , especially in the United States . Many of the issues that are settled within the scientific community , such as human responsibility for global warming , remain the subject of politically or economically motivated attempts to downplay , dismiss or deny them -- an ideological phenomenon categorised by academics and scientists as climate change denial . The sources of funding for those involved with climate science -- both supporting and opposing mainstream scientific positions -- have been questioned by both sides . There are debates about the best policy responses to the science , their cost-effectiveness and their urgency . Climate scientists , especially in the United States , have reported official and oil-industry pressure to censor or suppress their work and hide scientific data , with directives not to discuss the subject in public communications . Legal cases regarding global warming , its effects , and measures to reduce it have reached American courts . The fossil fuels lobby has been identified as overtly or covertly supporting efforts to undermine or discredit the scientific consensus on global warming .

Richard Lindzen <=SEP=> Richard Siegmund Lindzen ( born February 8 , 1940 ) is an American atmospheric physicist known for his work in the dynamics of the middle atmosphere , atmospheric tides , and ozone photochemistry . He has published more than 200 scientific papers and books . From 1983 until his retirement in 2013 , he was Alfred P. Sloan Professor of Meteorology at the Massachusetts Institute of Technology . He was a lead author of Chapter 7 , `` Physical Climate Processes and Feedbacks , '' of the Intergovernmental Panel on Climate Change 's Third Assessment Report on climate change . He has criticized the scientific consensus about climate change and what he has called `` climate alarmism . ''