The Republican-controlled Senate acknowledged Wednesday that climate change is real but refused to say humans are to blame.
The series of votes publicly tested Republicans' stance on global warming just days after two federal agencies declared 2014 the hottest year on record and hours after President Barack Obama called global warming one of the greatest threats to future generations.
It also came as Republicans in control of Congress moved to challenge Obama's actions to curb the pollution blamed for global warming. The votes were held during debate over a bill on the Keystone XL pipeline.
In a surprise move, Sen. James Inhofe of Oklahoma endorsed one of the measures, which passed 98-1 and read simply that "Climate change is real and not a hoax." But the senior Republican on the Senate Environment and Public Works Committee quickly made clear that he still thought humans were not to blame.
"Climate is changing and climate has always changed and always will. There is archaeological evidence of that, there is biblical evidence of that, there is historical evidence of that," said Inhofe. But "there are some people who are so arrogant to think they are so powerful they can change climate."
Many in his party were also unwilling to back measures Wednesday that said human activities -- primarily the burning of fossil fuels in vehicles, power plants and factories -- contributed to the warming of the planet. The vast majority of scientists have cited pollution from fossil fuels, chiefly emissions of carbon dioxide, as the main culprit in the Earth's temperature rise.
A measure sponsored by Sen. John Hoeven, the lead Republican on the pipeline bill, that said human beings contributed to the problem fell one vote short of the 60 needed for it to be adopted, but it was supported by 15 Republicans, including potential presidential candidate Sen. Rand Paul of Kentucky.
The Senate was closely divided, 50-49, on another measure that claimed human activities "significantly" altered the climate.
Despite the outcome, Sen. Barbara Boxer of California called the votes a "breakthrough moment in the climate change debate."
"We will go on the record, climate change is real and human activity contributes to climate change," Boxer said before the vote. "What a breath of fresh air this amendment is."
Many Republicans have either denied the science of climate change or distanced themselves from it, saying they don't have the expertise to issue an opinion.
On Tuesday, Obama addressed that head-on, saying in his State of the Union address, "I'm not a scientist, either." However, he said, "The best scientists in the world are all telling us that our activities are changing the climate." He he warned that climate change was the greatest threat to future generations.
League of Conservation Voters President Gene Karpinski said the two votes revealed that " bipartisan majority supports the science on climate change. But far too many senators are afraid to stand up to their polluter allies."
"At the same time, Republican leaders in the House are pretending the President's forceful call to action on climate change last night doesn't even exist," Karpinksi said. "The overwhelming majority of Americans understand that the facts on climate change are clear and want Washington to act."