Are government climate agencies tampering with climate data to show warming? Some Republicans think so. California Republican Rep. Dana Rohrabacher says to expect congressional hearings on climate data tampering.

@caerbannog666 expect there to be congressional hearings into NASA altering weather station data to falsely indicate warming￼ & sea rise — Dana Rohrabacher (@DanaRohrabacher) February 20, 2015

Rohrabacher is a senior member of the House Science, Space and Technology Committee, which has jurisdiction over NASA and other agencies that monitor the Earth’s climate.

Rohrabacher has long been critical of the theory of man-made global warming. Lately, the California Republican has criticizing NASA and the National Oceanic and Atmospheric Administration for allegedly tampering with temperature data to create an artificial warming trend. Such data is then used to justify regulations aimed at curbing fossil fuel use and other industrial activities.

@grngamine journalist investigation shows records of various weather stations altered by AGW advocates to make it appear to be warming. — Dana Rohrabacher (@DanaRohrabacher) February 19, 2015

@caerbannog666 U seem unaware of latest revelation of data manipulation. NASA reported higher temp than what was record at weather stations — Dana Rohrabacher (@DanaRohrabacher) February 19, 2015

Rohrabacher isn’t the only one to call for hearings on the science behind global warming. Oklahoma Republican Sen. Jim Inhofe has also promised to hold hearings on global warming data.

“We’re going to have a committee hearing on the science,” said Inhofe, who chairs the Senate Environment and Public Works Committee. “People are going to hear the other side of the story.”

For years, those skeptical of man-made global warming have argued that government agencies are altering raw temperature data to create a warming trend. Allegations of tampering have increased as satellite temperature readings show much less warming than land and ocean-based weather stations show.

Science blogger Steven Goddard (a pseudonym) has been a major critic of NASA’s and NOAA’s temperature measurements. Goddard points out that NOAA’s National Climatic Data Center makes the present look warmer by artificially cooling past temperatures to show a warming trend.

“NCDC pulls every trick in the book to turn the US cooling trend into warming. The raw data shows cooling since the 1920s,” Goddard told The Daily Caller News Foundation in an interview last month.

“NCDC does a hockey stick of adjustments to reverse the trend,” Goddard said. “This includes cooling the past for ‘time of observation bias’ infilling missing rural data with urban temperatures, and doing almost nothing to compensate for urban heat island effects.”

NOAA does make temperature adjustments, but it argues such adjustments are necessary to remove “artificial biases” in surface temperature data. The biggest adjustment made by NCDC scientists is cooling past data to take into account the fact that there was a big shift from taking temperature readings in the afternoon to the morning.

“We get a lot of people questioning our data adjustments,” Thomas Peterson, NCDC’s principal scientist, told TheDCNF. There was an “artificial cool bias in the data,” Peterson said.

Switching the time of the day temperatures were taken from the afternoon, when temperatures are warmer, to the morning, when temperatures are cooler, caused a cooling bias in the data. Temperature data from nearby weather stations was used to help create a baseline temperature for different regions.

But there are some drawbacks in surface temperature readings from a few thousand weather stations, boats and buoys spread out across the world. Peterson said the weather station system is “only really good for the U.S.”

“The main problem is where there are a few stations in the middle of nowhere.” Peterson said, specifically referring to weather station data problems on St. Helena Island.

UK Telegraph writer Christopher Booker joined the fray recently, using work by Goddard and other bloggers to criticize climate agencies for data tampering.

“Of much more serious significance, however, is the way this wholesale manipulation of the official temperature record… has become the real elephant in the room of the greatest and most costly scare the world has known,” Booker wrote. “This really does begin to look like one of the greatest scientific scandals of all time.”

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