Posts tagged Greenhouse

In February 2007, said the Intergovernmental Panel on Climate Change (IPCC) in its fourth assessment report that human actions are “very likely” (ie, 90% or greater probability) the cause of global warming by an increase of 0.75 degrees in average global temperature over the last 100 years or more. This statement is the result of very difficult discussions on a global scale between thousands of climate researchers whether human activity is the main cause of global warming. The results of this analysis were presented to the public in numerous publications, for example in the documentary by Martin Durkin, The Great Global Warming Swindle “, March 2007 UK Channel 4 presented. The main message of this production is that man on global warming” lies “and is” the biggest scam of modern times. “Martin Durkin and his colleagues believe that the scientific consensus on climate change, the result of a” peddle supports multi-billion dollar worldwide, created by fanatically anti-industrial environmentalists, scientists stories afraid to hunt and funding support from politicians and the media complicit. “The documentary shows scientists, politicians, economists, writers and others who are skeptical of the scientific consensus on anthropogenic (or man) of global warming. Some scientists against mainstream theories of greenhouse gas emissions, it is sufficient to say that he is still not , to determine whether humans are the main cause of global warming or whether other natural variations responsible for this phenomenon like increased solar activity, cosmic rays, or variations in the natural cycles of climate. There are also a number of scientific questions of the temperature records in databases such as differences used temperature through the greenhouse effect are reasonable small (fractions of C °). The so-called “Urban Heat Iceland” effect leads to a local warming in the more populated areas, are somewhat higher temperatures show due to increased heat generated by cities generated, rather than an increase in global temperature. However, this argument has been refuted by the IPPC Directive, indicating that the effect of urban heat island on the evolution of global temperature not more than 0.05 ° C (0.09 ° F) to 1990 degrees.

Other evidence was presented by the film showed that false or misinterpreted. The film asserts for example, to show that the records of atmospheric CO2 concentration since 1940 a steady increase, but in this period, the global temperature dropped to 1975 and has grown since then. In any case, it is generally recognized that this cooling is driven mostly by aerosols (pollution) into the atmosphere. There is nothing contradictory about this cooling, if all sources of radiation will change into account. A second argument that is easily discredited the effect of the so-called “solar variation theory” on global warming. According to the authors is solar activity (and with cosmic rays and solar heat to support the formation of clouds), currently at an extremely high and directly to changes in global temperature. The film argues that solar activity has far more impact on global warming than any other human or natural activity on Earth. What the film does not mention that solar activity has decreased over the past 30 years – along with the major peak in global temperature

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But there are some statements about the influence of oceanic mass and water vapor on climate change that are difficult to refute. Water vapor makes up about 98% of greenhouse gas volumes, and offers something between 40 to 80 percent of the natural greenhouse effect. He probably has the greatest impact on global temperature and climate conditions, much more than CO2. Water particles in clouds act to reflect incoming solar heat, but the film argues that the effects of clouds can not accurately simulate scientists try to future weather and its impact on global climate prediction. This argument is probably correct, and it is well known that water vapor is responsible for the natural warming of the surface temperature at about 30-35 ° C greenhouse gases of anthropogenic origin, the argument of the film is only about 2% of total greenhouse gas “natural” was an increase of 0.6 up to 0.7 ° C corresponds to temperature. This estimate is slightly to the simulation results much more sophisticated (from 0.9 to 2.7 º C) compared with lower, but it’s certainly an effect of anthropogenic CO2 by increasing the average surface temperature.

An example of the complexity of climatic simulations is the prediction of future storm events considering the effects of global warming. According to a recent study, published online in the journal Nature Geoscience by meteorologist Tom Knutson and research in the New York Times (May 18, 2008) resumed, global warming is not to blame for the recent increase in Atlantic hurricanes. The study predicts that by the end of the century, the number of hurricanes in the Atlantic fall by 18 percent. In the past, Knutson has raised concerns about the impact of climate change on storms. His new book has the potential to heat up a simmering debate among meteorologists about current and future effects of global warming in the Atlantic. And Knutson is not alone in this opinion. Another group of experts who study hurricanes and who say often skeptical about global warming also, there is no link between global warming and hurricane frequency. You write the recent increase to a natural cycle for several decades. Projections show that the number of hurricanes making landfall in the United States and its neighbors fell by about 30 percent because of wind factors. However, would the largest storms with winds of over 110km / h, only decrease in frequency by 8 percent. The largest decline is for storms with wind speeds of 39-73 mph (normal tropical storms), which would reduce by 27 percent expected.

It is not so good news from Knutson study, however. His computer model provides that “Hurricanes and tropical storms are growing stronger and wetter. Precipitation was within 30 miles of a hurricane to jump by 37 percent and wind strength should increase by around 2 percent,” said the study by Mr Knuth.

There are already critical reactions on this new publication. MIT hurricane claims meteorologist Kerry Emanuel that the computer model of Knuth’s not enough to just towers and used observed according to Kevin Trenberth, a climatologist at the National Center for Atmospheric Research in Boulder, Colo., Knutson’s computer model to the poor tropical climate assessment et ne”not reproduce the storms with any kind of loyalty.”It is not good enough to change the intensity, duration and size of storms, which is not only the number of hurricanes important to assess.

positive feedback comes from NOAA hurricane meteorologist Chris Landsea, who is not part of this study, praised the work comme”très line with what Knutson said the whole time .”” I think that the warming the climate is a major concern, but when it comes to hurricanes the evidence for changes is bloody tiny,”Landsea said.