On Wednesday, the Senate got together to take a few votes on whether global warming was real or not.

This was serious business, and they had a lot to think about. For 25 years now, the world's climate scientists have been warning that if we kept burning fossil fuels, the planet would get hotter.

"Emissions resulting from human activities are substantially increasing the atmospheric concentrations of greenhouse gases," the experts wrote in the first Intergovernmental Panel on Climate Change report back in 1990. "These increases will enhance the greenhouse effect, resulting on average in an increase in global warming."

Those scientists said the same thing in 1995.

They said it more loudly in 2001.

They said it louder still in 2007.

And they said it again in 2014. In that last report, in fact, climate scientists said they were now 95 percent sure that human activity was the dominant cause of global warming since 1950. They're about as sure of this as they are that smoking cigarettes causes cancer.

(NOAA)

So now it's 2015, and the Senate is debating a bunch of amendments on a bill to fast-track approval of the Keystone XL pipeline. On Wednesday, they were faced with a measure from Sheldon Whitehouse (D-RI) that said:

"To express the sense of the Senate that climate change is real and not a hoax."

That one was pretty easy. The Senate voted 98 to 1 in favor of this amendment. So far, so good.

But then came a tougher question. Sen. Brian Schatz (D-HI) put forward an amendment that said:

"To express the sense of the Senate that climate change is real; and human activity significantly contributes to climate change."

So the senators thought about it.

And thought about it.

This was a tricky one.

They thought some more.

In the end, just 50 senators voted "yes" on this question (every Democrat plus five Republicans).* But 49 senators voted "no" (all the other Republicans). The amendment failed to pick up the 60 votes necessary to overcome a filibuster and was rejected.

In conclusion, the Senate is pretty clearly a hoax.

Notes

* The 'yes' votes on the Schatz amendment were all Democrats and independents present, plus 5 Republicans: Lamar Alexander (TN), Kelly Ayotte (NH), Mark Kirk (IL), Susan Collins (ME), and Lindsey Graham (SC). The remaining 49 Republicans voted no.

** There was also a separate grab-bag amendment from John Hoeven (R-ND) which stated that Congress should nix policies that hurt jobs, that Keystone XL wouldn't be harmful to the environment, and also that "climate change is real and humans contributed to it." This was meant to give Republicans cover for voting against Schatz's amendment.

But even this amendment ended up failing, only getting 59 votes. The bill picked up all Democrats present, plus 14 Republicans: Alexander, Ayotte, Kirk, Collins, Graham, as well as Bob Corker (TN), Jeff Flake (AZ), Orrin Hatch (UT), Dean Heller (NV), John McCain (AZ), Lisa Murkowski (AK), Rand Paul (KY), Rob Portman (OH), Mike Rounds (SD), and Pat Toomey (PA). The remaining 40 Republicans, plus Bernie Sanders (I-VT), voted against.

Further reading

-- It's official: 2014 was the hottest year ever recorded

-- The science of global warming has changed a lot in 25 years. The conclusions haven't.

-- 9 questions about the Keystone XL pipeline debate you were too embarrassed to ask