Update: New NASA map of sea ice minimum

Bad Astronomy
The entire universe in blog form
Aug. 27 2012 12:12 PM

Update: New NASA map of sea ice minimum

Earlier, I wrote that arctic sea ice had yesterday reached record low levels, blowing through the previous lowest-seen minimum in 2007, even though there's still a lot of melting left to go.

NASA just released this visualization of the arctic region showing just how bad it is:

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

Advertisement

The white area is the extent of sea ice as of August 26, 2012. The orange line is the average minimum extent from 1979 - 2010, the time covered by satellite observations. In other words, every year they measure the outline of the ice when it reaches its minimum, usually in September, and then averaged those positions for that timespan.

As you can see, we've been well below the usual minimum ice extent for some time - not just where we usually are this time of year, but the actual minimum amount... and we still have weeks of melting yet to go.

I want to note that this does not necessarily mean we'll see sea level rising from this. That ice is floating on the water, and in general when ice melts the water level stays the same. You can see this for yourself: put ice in a glass, then fill it with water. Mark the level. Wait until the ice melts and you'll see the level hasn't changed. The ice displaces (pushes aside) an amount of water exactly equal to its own weight, so when it melts that water fills up the same volume the ice displaced. The level stays the same.

However, because ice is frozen fresh water, and the sea is salt water, floating ice may actually raise the sea level a bit. Still, the far bigger concern is ice on land that melts and flows into the ocean. That certainly can raise the sea level. Greenland has the second largest reservoir of frozen water on Earth, and it's seeing unprecedented melting.

So yeah, global warming is a concern, no matter how many people deny it. And it's not something we should blow off and worry about later. It's happening now.

Image credit: Scientific Visualization Studio, NASA Goddard Space Flight Center



Related Posts:


TODAY IN SLATE

The World

How Canada’s Shooting Tragedies Have Shaped Its Gun Control Politics

Where Ebola Lives Between Outbreaks

Gunman Killed Inside Canadian Parliament; Soldier Shot at National Monument Dies

Sleater-Kinney Was Once America’s Best Rock Band

Can it be again?

Paul Farmer: Up to 90 Percent of Ebola Patients Should Survive

Is he right?

Science

“I’m Not a Scientist” Is No Excuse

Politicians brag about their ignorance while making ignorant decisions.

Technology

Driving in Circles

The autonomous Google car may never actually happen.

In Praise of 13th Grade: Why a Fifth Year of High School Is a Great Idea 

PowerPoint Is the Worst, and Now It’s the Latest Way to Hack Into Your Computer

  News & Politics
Politics
Oct. 22 2014 9:42 PM Landslide Landrieu Can the Louisiana Democrat use the powers of incumbency to save herself one more time?
  Business
Continuously Operating
Oct. 22 2014 2:38 PM Crack Open an Old One A highly unscientific evaluation of Germany’s oldest breweries.
  Life
Gentleman Scholar
Oct. 22 2014 5:54 PM May I Offer to Sharpen My Friends’ Knives? Or would that be rude?
  Double X
The XX Factor
Oct. 22 2014 4:27 PM Three Ways Your Text Messages Change After You Get Married
  Slate Plus
Tv Club
Oct. 22 2014 5:27 PM The Slate Walking Dead Podcast A spoiler-filled discussion of Episodes 1 and 2.
  Arts
Brow Beat
Oct. 22 2014 9:19 PM The Phone Call Is Twenty Minutes of Pitch-Perfect, Wrenching Cinema
  Technology
Future Tense
Oct. 22 2014 5:33 PM One More Reason Not to Use PowerPoint: It’s The Gateway for a Serious Windows Vulnerability
  Health & Science
Wild Things
Oct. 22 2014 2:42 PM Orcas, Via Drone, for the First Time Ever
  Sports
Sports Nut
Oct. 20 2014 5:09 PM Keepaway, on Three. Ready—Break! On his record-breaking touchdown pass, Peyton Manning couldn’t even leave the celebration to chance.