Today President Obama nominated Ernest Moniz to head the Department of Energy, as widely expected. If confirmed, he'll replace outgoing Energy Secretary Steven Chu. Moniz, like Chu, is a super-brainy physicist.

Here's what Philip Bump wrote about Moniz last month on the pages of Grist:

Who is Ernest Moniz?

Here's who he is, as articulated by Reuters:

Moniz, a former undersecretary of energy during the Clinton administration, is director of the Massachusetts Institute of Technology's Energy Initiative, a research group that gets funding from industry heavyweights including BP, Chevron, and Saudi Aramco for academic work on projects aimed at reducing greenhouse gases.

The U.S. State Department just released a draft environmental impact statement for the Keystone XL pipeline, and it's not what climate activists have been hoping for.

As The New York Times puts it, the report "makes no recommendation about whether the project should be built but presents no conclusive environmental reason it should not be." According to The Washington Post, the report "suggest[s] that blocking the project would not have a significant impact on either the future development of Canada’s oil sands region or U.S. oil consumption."

More from the Times:

The new impact statement says that extracting, shipping, refining and burning oil from the tar sands produces more climate-altering greenhouse gases than most conventional oil, but less than many of the project’s critics claim. The State Department study says that tar sands oil produces 5 percent to 19 percent more greenhouse gas emissions than other crude, depending on what oil was compared and who performed the calculations.

Green Thing encourages people to walk more, cut back on meat, buy less, turn down the thermostat, waste and fly less, and unplug vampire electronics. So every day until Earth Hour on March 23, the London-based nonprofit is publishing a poster to promote those green habits.

And some big designer names contributed to the project, including Google Creative Director Tom Uglow and London 2012 Olympics logo designer Patrick Cox. Green Thing knows "that a dig, joke, or nudge is way more effective than another weeping seal cub,” Cox said in a press release for the project. Follow the project on Green Thing.

Editor’s note: The chat’s now over, but you can replay it in full.

Neal Gorenflo is the founder and publisher of Shareable, a website dedicated to promoting the sharing economy in all its forms, from car sharing to tool-lending libraries and even pet sharing. A former corporate up-and-comer, he quit his job in 2004 and vowed to “make a world where people felt like they were part of something meaningful.”

Gorenflo chatted with Grist earlier this month as part of our two-month exploration of the sharing economy -- and now, he’s offered to talk to you, too. Join us this Friday at 1 p.m. Eastern (10 a.m. Pacific), for a live chat, moderated by Grist Senior Editor Greg Hanscom.

Got something to share? Click here to join the chat.

Here's a live stream of Sunday's "Forward on Climate" rally on the National Mall:

http://www.youtube.com/watch?v=1Q2YpdHuBCA

Forty-eight climate activists got themselves hauled away by the cops on Wednesday, part of a Sierra Club action in front of the White House to protest the Keystone XL pipeline. It was the first time in the Sierra Club's 120-year history that the group has sanctioned civil disobedience. As we reported yesterday, those arrested included Sierra Club Executive Director Michael Brune, Bill McKibben of 350.org (and Grist’s board), civil rights leader Julian Bond, actress Daryl Hannah, Robert F. Kennedy Jr., and his son Conor Kennedy (aka Taylor Swift's ex).

Jay Mallin captured the highlights on video:

Each year at this time, Grist’s writers and editors walk, hats in hand, to the people who keep track of the traffic numbers here. Each year, we hope against hope that one of our stories has made the list of the top-10 most clicked stories on the site -- maybe it’ll be that wonky piece about what the Census numbers tell us (and don't) about the so-called “urban renaissance,” or the one about “discount rates” and climate change. Oh come on, we can hope, can't we?

OK, no. We’ve had our fun over the past week hand-picking our favorite stories about bikes, genius kids, cities, and the likes. But this last list is drawn straight from the data, based solely on the number of “unique pageviews” each story received. And let’s just say it doesn’t always leave us feeling optimistic about the future of life on this rock.

Without further ado, the 10 most popular stories from Grist in 2012. If you need us, we’ll be huddled around a bottle of whiskey, resigning ourselves to running more stories about baby pandas and penguin sweaters in 2013 -- and toasting Jess Zimmerman and her crack team of Grist List bloggers who keep the hordes stampeding to our url, despite our best efforts to drive them away.

Looking for a quality way to spend a few hours while the clock ticks down to 2013? We dug back through the cities archives from the past year in search of quality writing that merits a second, or even a third look. Here are our faves.

1. San Francisco artist mends clothes and builds community -- just by giving a darn

In which Darby Minow Smith writes about Michael Swaine, who has mended clothing for free on the San Francisco streets for the past 11 years. Here’s Swaine talking about one of his regulars, Veronica, who likes to hang out and chat even when her mending is done:

"The truth is, I love when people stay. I bring chairs out. I never try to kick anyone out. Maybe it’s kind of like a consumer thing. When you go to a restaurant and you finish eating, you should leave. Someone else will want that chair. I think there’s something touching and beautiful about this other function … Veronica has lots of things that she needs mended, but she also really needs someone to listen to her, and someone to talk to."

2. Jane addiction: Can one humble city-lover be all things to all people?

In which Sarah Laskow takes a walk through New York to commemorate Jane Jacobs -- “writer, grassroots organizer, patron saint of city lovers everywhere.”

"These days, it’s impossible to avoid Jacobs’ legacy when thinking about cities. But it’s almost as tricky to pin down what, exactly, her legacy is. Great American Cities is long (458 pages) and, in places, boring. (Full disclosure: I’ve read about half altogether -- definitely most of Part One, and sections of the other three parts.) Plenty of people who adore Jacobs haven’t read the whole thing, or any of her eight other books. She’s become, for many people, a stand-in for the idea that cities are awesome. If there’s some aspect of a vibrant city that you happen to like, well, you’re pretty safe asserting that Jane would have liked it too."

In April, our Ask Umbra advice column turned 10 years old. To celebrate, Umbra Fisk sat down with an organic carrot cake and compiled the 10 most notable moments in Ask Umbra history. Spoiler alert! Her No. 1 highlight of the decade was you -- her dear readers, whose questions "never cease to perplex, amaze, and amuse.”

Umbra is on vacation this week, so, as we count down to 2013, we rounded up the 10 best questions readers sent in this year. You can read her sage replies by clicking on the headlines.

Happy new year!

Ball droppingly,
The Grist staff

Apparently Gristers aren’t the only ones feeling discontent with America’s holiday traditions. Our campaign to “shift the gift” this season has taken on a life of its own on Twitter and attracted the attention of two national TV news programs -- first 20/20 and now the Jane Velez-Mitchell show on HLN.

Grist Senior Editor Greg Hanscom, who is on a campaign to create the best Christmas ever for his wife and two young daughters -- without buying them any presents -- appeared with Velez-Mitchell yesterday on a spot called, “A happier, more memorable holiday?” Here it is: