Today’s big news is that EPA has officially determined that greenhouse-gas emissions pose a threat to public health and welfare. Over at Gristmill, Kate Sheppard explains what this all means (and tells you how to submit a public comment), Jonathan Hiskes and rounds up reactions from industry, environmentalists, and politicians.

Elsewhere:

Peter Lehner at NRDC’s Switchboard applaud’s President Obama’s speech about the three elements of the high-speed rail program, which got $13 billion from the stimulus bill.

The Ethicurean’s Bonnie P. interviews Superbug’s Maryn McKenna, who gives a great explanation of what’s going on with the MRSA bacteria and why we should be worried.

Jonathan Cohn at The Treatment considers what a statement from White House Office of Health Reform director Nancy-Ann DeParle means about the administration’s feelings on a public insurance option.

Janet Stemwedel at Adventures in Ethics and Science grapples with the task of sniffing out bias in industry funding of drug research.

Jovana Ruzicic at Enviroblog shows us the downside of the Green Revolution for India’s farmers.

Teresa Lanza at RH Reality Check explains how Bolivia’s new constitution upholds the health and rights of women and girls.

Ed Yong at Not Exactly Rocket Science highlights research that found a simple writing exercise to improve black students’ achievement.