Despite receiving a subpoena from the House of Representatives, the National Oceanic and Atmospheric Administration (NOAA) continues to defy the summons to explain itself regarding a controversial climate study it had released back in June.

An aide to the House Committee on Science, Space and Technology said the NOAA has refused to provide documents related to a report that suggested there has been no reduction in global warming rates, as was initially thought.

Most climate experts believe that global warming is caused by carbon emissions from burning fossil fuels.

Texas Rep. Lamar Smith, chairman of the House committee, said that they would make use all available tools to carry out its oversight activities on the environment agency.

"It was inconvenient for this administration that climate data has clearly showed no warming for the past two decades," Smith said.

"The American people have every right to be suspicious when NOAA alters data to get the politically correct results they want and then refuses to reveal how those decisions were made."

The House science committee chair added that the environment agency needs to tell the truth as to why it chose to alter the data to achieve the results it needed to promote the Obama administration's drastic agenda on climate change.

He said the NOAA has not yet identified any legal basis for allowing documents regarding its study to be withheld.

Members of the Democratic Party and other experts on climate change have criticized Smith this week, accusing the committee chair of attacking researchers who release findings contrary to his own personal beliefs.

People close to the House science committee, however, claim that the ongoing investigation is crucial to its oversight efforts and that it is not designed to target climate scientists.

The committee's subpoena requires all communications made by government officials regarding the NOAA climate report and its release to the public, not only the researchers who carried out the study.

Tom Karl, head of the NOAA's environmental information centers, conducted the study on global warming. His report suggested that global warming rates in the past 15 years have occurred at a faster pace than the ones observed during the decades before the start of the 21st century.

Karl made use of temperatures collected from around 30,000 different surface stations for the recent study, instead of only 7,000 surface stations featured in earlier reports.His report included temperature data from 2014, which is considered to be the year with the highest temperatures ever to be recorded.

NOAA communications director Ciaran Clayton said the environment agency has already complied with the committee's requests for information, methodologies and discussions regarding the climate report.

The NOAA, however, refuses to provide communications that may include confidential scientific discussions.

Clayton denied allegations that the climate report was politically motivated, or that it was conducted to advance any agendas.

She said the agency's findings are the product of scientists carrying out their responsibilities to provide the best report on historical trends of global temperatures for decision makers in the government, including members of Congress.

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