Susan Walsh / AP

When asked if he believes CO2 is the primary contributor to global warming, EPA chief Scott Pruitt said "no," on Squawk Box this morning.

"I think that measuring with precision human activity on the climate is something very challenging to do and there's tremendous disagreement about the degree of impact, so no, I would not agree that it's a primary contributor to the global warming that we see."

NASA and NOAA released independent analyses in January showing earth's surface temperatures were the warmest on record, a change driven largely by CO2, and it is the overwhelming scientific view that human induced carbon emissions are the most important force behind current warming.

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Updated 45 mins ago - Politics & Policy

Biden seeks $2 trillion clean energy and infrastructure spending boost

Photo: Timothy A. Clary/AFP via Getty Images

Joe Biden expanded his energy and climate plans Tuesday with a call for spending $2 trillion over four years on climate-friendly infrastructure — a proposal the campaign is casting as part of a wider economic recovery package.

Why it matters: The plan, which is the focus of a speech Biden will deliver this afternoon, represents a long-anticipated plan to move his climate platform further left and make it more expansive.

2 hours ago - Health

4 former CDC heads say Trump's undermining of agency puts lives at risk

CDC director Robert Redfield and President Trump. Photo: Drew Angerer/Getty Images

Four former directors of the Centers for Disease Control and Prevention blasted the Trump administration's "repeated efforts to subvert" agency guidelines related to reopening schools, accusing the White House in a scathing Washington Post op-ed of undermining science with "partisan potshots."

Why it matters: Former directors Tom Frieden, Jeffrey Koplan and David Satcher and acting head Richard Besser served in parts of the Obama, Bush and Clinton administrations. They said they "cannot recall over our collective tenure a single time when political pressure led to a change in the interpretation of scientific evidence."

Chinese students at U.S. colleges face deep uncertainty

Illustration: Annelise Capossela/Axios

A new visa guideline issued last week would strip international students in the U.S. of their student visa if their college classes are online-only amid the pandemic.

Why it matters: More than 360,000 Chinese students are enrolled at U.S. colleges. Many of them could be forced to return to China if the rule change is implemented.