Someone tipped off Stephen Colbert to the recent rant against the city's new bikeshare system by Wall Street Journal editorial board member Dorothy Rabinowitz  -- and thank god for that. "The most important danger in the city is not the yellow cabs. It is the bicyclists," Rabinowitz says, adding that the new "blazing blue" bikes-for-rent have "begrimed" the city's neighborhoods. Uh, we'll just let Stephen take it from there.

Editor's note: The chat's over now, but you can watch a replay of Revkin's conversation with David Roberts.

Andrew Revkin has been on the front lines of environmental journalism for decades. He picked up the climate story before many of us had heard of it. He's best known for his Dot Earth blog at the New York Times, where he covered environmental issues as a reporter from 1995 to 2009.

Momentous change doesn't always leave visual cues. A 2008 Obama looks much the same as a 2012 Obama (minus a few gray hairs and Benghazi wrinkles). In some ways, climate change is similar; we can't exactly see villainous clouds of CO2 strangling the sky. But when it comes to glaciers, climate change leaves marks that can be seen from space.

Our friends at GlacierWorks hope to document those scars. Respected mountaineer and GlacierWorks Executive Director David Breashears retraced the steps of past photographers from the Royal Geographical Society to reshoot photos of famous Himalayan glaciers affected by climate change. Thanks to their hard work and internet magic, we can now compare the severity of ice recession by combining the historic and modern images.

On the left is a photo taken by Major E. O. Wheeler in 1921 on the North slope of 26,906-foot Cho Oyu; on the right is a photo taken by Breashears from a similar perspective  in 2009. Drag the slider to check out the changes China's Kyetrak Glacier experienced.

Now compare the Main Rongbuk Glacier (near Mt. Everest) in a 1921 photo by George Mallory to Breashears'  2007 image:

Thanks to all of you who took the Gross National Happiness survey, a project of The Happiness Initiative. (And if you haven't taken it yet, you still can!) It’s designed to measure your overall satisfaction with life as well as your sense of well-being across a number of specific categories. Do you feel good about your physical health? The educational and cultural opportunities in your community? Your work life? Your time balance? The environment where you live?

We’ve now gotten the results back for Grist readers and compared them to responses from a random sample of U.S. residents. The bottom line: You guys are a mostly happy bunch, but still a little more bummed out than the average American.

We asked, and you shared. From moss walls to local picnics to highway cleanups, check out what your fellow readers got up to on this fine Earth Day:

This year, Earth Day annexed a whole weekend for reflection, fun, and simple acts of change. What are you doing to celebrate? Grist wants to know: Show us in words, photos, videos, tweets, Vines, comments, and smoke signals.

Share your pictures and the stories behind them on Facebook, in the comments below, or on Twitter and Instagram using the hashtag #tellgrist.

You've seen our illustrated history of the Keystone XL pipeline. Now, you can enjoy it with snazzy sound effects:

Editor's note: The debate's now over, but you can watch a replay of the discussion below.

Be here on Thursday, April 18, at 6:30 p.m. ET (3:30 PT), to watch a live debate and discussion:

Keystone XL: The science, stakes, and strategy behind the tar-sands pipeline fight

Hosted by Climate Desk
Moderated by Chris Mooney
Guests: David Roberts of Grist, May Boeve of 350.org, Michael Levi of the Council on Foreign Relations, and Michael Grunwald of Time

One week ago, residents of rural Mayflower, Ark., found a river of reeking, black oil flowing through their backyards and streets. ExxonMobil, the company that owns the ruptured pipeline, evacuated the neighborhood and quickly instated something like martial law, evicting wildlife rescue workers, threatening reporters with arrest, and even winning a temporary no-fly zone over the spill. Here's what the company is hiding, care of the EPA's on-site coordinator web page -- which was locked down shortly after we retrieved these photos. (UPDATE: The page is unlocked again. Feel free to peruse the whole collection.)

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

Christie Aschwanden is a prolific magazine writer and author of, among other things, Beautiful Chickens, a coffee-table book packed with glam shots of champion poultry breeds. She is also the daughter of a pilot and a recovering jet setter.

As part of Grist's March theme, "Get Small: Micro solutions to macro problems," Ashwanden wrote about her yearlong experiment in living local. In an effort to reduce her climate footprint, she swore off air travel for 12 months and vowed to stay within a 100-mile radius of her home on a farm in western Colorado.

First World problems, for sure, but some of what she discovered was a little mind-boggling -- the ability of a single plane trip to negate all of our other good green deeds, for example. Perhaps the most surprising discovery of all, however, was just how happy and content she could be living small.