On balance, clouds cool the earth. Dense, low-lying clouds are responsible for most of that effect, because they reflect sunlight back to space. Many high, thin clouds have the opposite influence, allowing incoming sunshine to pass through but effectively trapping heat that is trying to escape.
Humans are perturbing the earth's heat balance by releasing greenhouse gases, which block heat trying to escape. The most elaborate computer programs have agreed on a broad conclusion: clouds are not likely to change enough to offset the bulk of the human-caused warming. Some predict that clouds could actually amplify the warming trend sharply through several mechanisms, including a reduction of some of the low clouds that reflect a lot of sunlight back to space.
So why does a certain Doctor Lindzen, who appears regularly at the Heartlands Institute, the primary American organisation pushing climate change scepticism, refute this evidence? His theory goes along the lines of the following. Lindzen has said that when surface temperature increases, the columns of moist air rising in the tropics will rain out more of their moisture, leaving less available to be thrown off as ice, which forms the thin, high clouds known as cirrus. Just like greenhouse gases, cirrus clouds act to reduce the cooling of the earth, and a decrease of them would counteract the increase of greenhouse gases. Lindzen calls this the iris effect, after the iris of the eye, which opens at night to let in more light. The earth's "iris" of high clouds would be opening to let more heat escape.
Many of his colleagues in the M.I.T. atmospheric sciences department are critical of his stance. Most of his data they say is flawed and his theory makes assumptions that are inconsistant with known facts. Yet, he still insists that other scientists are determined to suppress his views because he shows dissent to the known science.
We at Sven Radio are simply astounded that a person like this is believed. What on earth does this man think he is doing? It's as plain as the nose on your face, that this damn fool is supported by foundations in whose interests it is to promte the so-called "myth" of global warming. Ultimately it will become obvious how clouds are reacting, but that could take decades, by which point it would be too late, and by then the atmosphere would contain so much carbon dioxide as to make substantial warming inevitable, and the gas would not return to normal for thousands of years!