By Amber Jenkins

An interesting recent paper from Dr. Son Nghiem at NASA’s Jet Propulsion Laboratory and colleagues finds that the bottom of the Arctic Ocean controls the pattern of sea ice thousands of feet above on the water’s surface. The seafloor topography exerts its control not only locally, in the Bering, Chukchi, Beaufort, Barents and Greenland Seas, but also spanning hundreds to thousands of miles across the Arctic Ocean.

How? The seafloor influences the distribution of cold and warm waters in the Arctic Ocean where sea ice can preferentially grow or melt. Geological features on the ocean bottom also guide how the sea ice moves, along with influence from surface winds.

Interestingly, the study also links the bottom of the Arctic Ocean with cloud patterns up in the sky. The ocean bottom affects sea ice cover, which affects the amount of vapor coming from the surface of the ocean out into the air, which in turn influences cloud cover.

The researchers, who also come from NASA’s Goddard Space Flight Center, the Applied Physics Laboratory and the National/Naval Ice Center in the U.S., use sea ice maps taken from space with NASA’s QuickSCAT satellite, as well as measurements from drifting buoys in the Arctic Ocean. They compare the sea ice and seafloor topography patterns to identify the connection between the two.

Bottom line:

Since the seafloor does not change significantly over many years, sea ice patterns can form repeatedly and persist around certain underwater geological features. So computer models need to incorporate these features in order to improve their forecasts of how ice cover will change over the short- and long-term. This ‘memory’ of the underwater topography could help refine our predictions of what will happen to ice in the Arctic as the climate changes.

Source:

“Seafloor Control on Sea Ice,” S. V. Nghiem, P. Clemente-Colon, I.G. Rigor, D.K. Hall & G. Neumann, Deep Sea Research Part II: Topical Studies in Oceanography, Volumes 77-80, pp 52-61 (2012).

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.

By Amber Jenkins

    Earth at night, as seen by the Suomi National Polar-orbiting Partnership (NPP) satellite, a joint effort by NASA and the National Oceanic and Atmospheric Administration (NOAA). Courtesy of NASA Earth Observatory and NOAA National Geophysical Data Center.

This is a new image of our planet at night, as taken by a new NASA and National Oceanic and Atmospheric Administration (NOAA) satellite orbiting above us. Scientists recently unveiled this global composite image (and the one below), constructed using cloud-free nighttime images. They show the glow of natural and man-made phenomena across the planet in greater detail than ever seen before. City lights can tell us about how humans have spread across the globe.

Many satellites are equipped to look at Earth during the day, when they can observe our planet fully illuminated by the sun. But with a new sensor onboard the NASA-NOAA Suomi National Polar-orbiting Partnership (NPP) satellite launched last year, scientists now can observe Earth’s atmosphere and surface during nighttime hours.

For more Earth at night images, see this article.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.

By Amber Jenkins

This post was written for My Big Fat Planet, a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.

COLD SNAP: Petermann Glacier, Greenland. Left: June 26, 2010. Right: August 13, 2010. An iceberg more than four times the size of Manhattan broke off the Petermann Glacier (the curved, nearly vertical stripe stretching up from the bottom right of the images) along the northwestern coast of Greenland. Warmer water below the floating ice and at the sea’s surface were probably responsible for the break.
› See more images of our changing Earth from State of Flux

They say a picture says a thousand words. This week we published our 100th image in State of Flux, our gallery showing images of change around our planet. So hopefully by now you’re in awe of our home planet and the ways in which it is constantly changing, and aware of the impact us humans can have.

Each week for the past couple of years, we’ve published new images of different locations on planet Earth, showing change over time periods ranging from centuries to days. The pictures have been taken from space, by NASA’s Eyes on the Earth (its fleet of satellites whizzing above our heads), and from the ground, by real-life people. Some of the changes seen are related to, or exacerbated by, climate change, and some are not. Some document the effects of urbanization and man’s impact on the land, while others the ravage of disasters such as fires and floods.

Seeing our planet from space gives us a global view that we can’t get elsewhere. Through those eyes, we’ve witnessed damage caused by the recent tsunami in Japan, glacier melt in the Himalayas, the greening of China, the growth of Las Vegas and a century of global warming. We’ve looked at the march of deforestation in Bolivia, the rumblings of the (unpronounceable) Icelandic volcano Eyjafjallajökull, and the damming of the River Nile. Take a look below at some of our favorites. Sign up to our monthly newsletter or subscribe to our Facebook page if you want to keep up to date with our latest images. We’ll be launching a brand spanking new version of the gallery soon!

See more of some of the most stunning images from State of Flux on My Big Fat Planet.

By Erik Conway, writing for My Big Fat Planet

Mars has been a grand scientific mystery ever since the first modern images were beamed back from the Mariner 4 spacecraft in 1965. Those snapshots showed a moon-like, cratered surface — not what we expected. Scientists had assumed that Mars would have an Earth-like atmosphere, composed mainly of nitrogen and with traces of carbon dioxide and water vapor. What they found instead was a cold desert world, one that possessed a thin wisp of an atmosphere containing only carbon dioxide.

Subsequent missions to the Red Planet detected tiny amounts of water vapor in Mars’ atmosphere, and better images began to unveil what looked like river channels and deltas on the surface. Indeed, spacecraft launched in the late 1990s and 2000s found water on Mars in the form of ice, bound into the planet’s soil and in great underground deposits. Water used to flow on the surface of Mars. But how? And where did it all go?

At first sight, the facts defy logic. According to astronomers, the sun used to be dimmer (i.e. colder) than it is now, meaning that Mars (and Earth) should have been colder in the past, not warmer. But observations tell us that it was clearly warmer and wetter on Mars in the past — not colder and more frozen. How did Mars buck the trend and stay toasty in the past? The most likely answer is that it used to have some sort of “super greenhouse effect” going on, the like of which we see on Venus. On Venus, the thick carbon-dioxide-based atmosphere traps the sun’s heat, resulting in surface temperatures that are hot enough to melt lead. Scientists think that early Mars also had a thick, carbon-dioxide-rich atmosphere that provided warming.

That said, in a recent talk at the American Geophysical Union conference in San Francisco, Mars specialist Bruce Jakosky of the University of Colorado pointed out that heat-trapping carbon dioxide alone would not have been sufficient to make Mars warm enough and wet enough to match our observations. Carbon dioxide’s ability to trap heat would have at some point “saturated”, or maxed out. Other greenhouse gases, like methane or ammonia, might have helped trap more heat near the surface of Mars — but they would not have been sufficient either because the sun’s ultraviolet radiation would have destroyed them far too quickly. Ergo, some sort of ultraviolet-absorbing layer high in Mars’ atmosphere would have been needed to help trap the heat. (The Earth’s ozone layer, which dates back to somewhere between 2 and 2.7 billion years ago, performs this service for us now.)

There is, as yet, no evidence of the necessary chemicals on Mars to do this. Jakosky didn’t draw any firm conclusions about how the warmer Mars could have existed. But he did lay out possible future investigations that might help uncover parts of this mystery a little more clearly. One of those includes the MAVEN mission to Mars, scheduled for launch in 2013, which will study how Mars’ atmosphere and climate has changed over time.

As Jakosky has said, in some ways, Mars is a very Earth-like planet. By looking at conditions on other worlds, we can gain insights into how, and why, our own climate is changing here on planet Earth.

You can read more about the Mars Science Laboratory rover here. Scheduled for launch in the fall of 2011, the Curiosity rover will help determine whether Mars has in the past, or does today, harbor life.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.

By Amber Jenkins

I stumbled upon this video earlier today. It’s Isaac Asimov, famous science fiction writer and biochemist, talking about global warming — back in January 1989. If you change the coloring of the video, the facial hair style, and switch out Asimov for someone else, the video could pretty much have been made today.

Asimov was giving the keynote address at the first annual meeting of The Humanist Institute. “They wanted me to pick out the most important scientific event of 1988. And I really thought that the most important scientific event of 1988 will only be recognized sometime in the future when you get a little perspective.”

What he was talking about was the greenhouse effect, which, he goes on to explain, is “the story everyone started talking about [in 1988], just because there was a hot summer and a drought.” (Sound familiar, letting individual weather events drive talk of whether the Earth’s long-term climate is heating up or cooling down??)

The greenhouse effect explains how certain heat-trapping (a.k.a. “greenhouse”) gases in our atmosphere keep our planet warm, by trapping infrared rays that Earth would otherwise reflect back out into space. The natural greenhouse effect makes Earth habitable — without our atmosphere acting like an electric blanket, the surface of the earth would be about 30 degrees Celsius cooler than it is now.

The problem comes in when humans tinker with this natural state of affairs. Our burning of fossil fuels (coal, oil and gas) constantly pumps out carbon dioxide — a heat-trapping gas — into the atmosphere. Our cutting down of forests reduces the number of trees there are to soak up some of this extra carbon dioxide. All in all, our atmosphere and planet heats up, (by about 0.6 degrees Celsius since the Industrial Revolution) with the electric blanket getting gradually thicker around us.

“I have been talking about the greenhouse effect for 20 years at least,” says Asimov in the video. “And there are other people who have talked about it before I did. I didn’t invent it.” As we’ve stressed here recently, global warming, and the idea that humans can change the climate, is not new.

As one blogger notes, Asimov’s words are as relevant today as they were in 1989. “It’s almost like nothing has happened in all this time.” Except that Isaac Asimov has come and gone, and the climate change he spoke of is continuing.

Asimov’s full speech can be seen here.

This post was written for “My Big Fat Planet,” a blog hosted by Amber Jenkins on NASA’s Global Climate Change site.