A new NASA and university analysis of ocean data collected more than 135 years ago by the crew of the HMS Challenger oceanographic expedition provides further confirmation that human activities have warmed our planet over the past century.
Researchers from the University of Tasmania, Sandy Bay, Australia; and NASA’s Jet Propulsion Laboratory, Pasadena, Calif., combined the ship’s measurements of ocean temperatures with modern observations from the international Argo array of ocean profiling floats. They used both as inputs to state-of-the-art climate models, to get a picture of how the world’s oceans have changed since the Challenger’s voyage.
The Challenger expedition, from 1872 to 1876, was the world’s first global scientific survey of life beneath the ocean surface. Along the way, scientists measured ocean temperatures, lowering thermometers hundreds of meters deep on ropes.
“The key to this research was to determine the range of uncertainty for the measurements taken by the crew of the Challenger,” said Josh Willis, a JPL climate scientist and NASA project scientist for the upcoming U.S./European Jason-3 oceanography satellite, scheduled to launch in 2015. “After we had taken all these uncertainties into account, it became apparent that the rate of warming we saw across the oceans far exceeded the degree of uncertainty around the measurements. So, while the uncertainty was large, the warming signal detected was far greater.”
Uncertainties around the Challenger’s measurements were caused by the limited areas measured during the voyage; the actual depths the thermometers descended to; and the likely natural variation in temperature that could occur in each region during the voyage.
“Our research revealed warming of the planet can be clearly detected since 1873 and that our oceans continue to absorb the great majority of this heat,” said researcher and lead author Will Hobbs of the University of Tasmania’s Institute for Marine and Antarctic Studies and the Australian Research Council’s Centre of Excellence for Climate System Science. “Currently, scientists estimate the oceans absorb more than 90 percent of the heat trapped by greenhouse gases, and we attribute the global warming to anthropogenic (human-produced) causes.”
The Challenger expedition measurements also revealed that thermal expansion of sea water caused by global warming contributed about 40 percent of the total sea level rise seen in tide gauges from 1873 to 1955. The remaining 60 percent was likely to have come from the melting of ice sheets and glaciers. Prior to this research, climate models offered the only way to estimate the change before the 1950s.
Results of the study are published in the journal Geophysical Research Letters.
For more on the study, visit: imas.utas.edu.au .
Comets visible to the naked eye are a rare delicacy in the celestial smorgasbord of objects in the nighttime sky. Scientists estimate that the opportunity to see one of these icy dirtballs advertising their cosmic presence so brilliantly they can be seen without the aid of a telescope or binoculars happens only once every five to 10 years. That said, there may be two naked-eye comets available for your viewing pleasure this year.
“You might have heard of a comet ISON, which may become a spectacular naked-eye comet later this fall,” said Amy Mainzer, the principal investigator of NASA’s NEOWISE mission at the Jet Propulsion Laboratory in Pasadena, Calif., and self-described cosmic icy dirtball fan. “But if you have the right conditions you don’t have to wait for ISON. Within a few days, comet PANSTARRS will be making its appearance in the skies of the Northern Hemisphere just after twilight.”
Discovered in June 2011, comet 2011 L4 (PANSTARRS) bears the name of the telescopic survey that discovered it — the less than mellifluous sounding “Panoramic Survey Telescope and Rapid Response System” which sits atop the Haleakala volcano in Hawaii.
Since its discovery a year-and-a-half ago, observing comet PANSTARRS has been the exclusive dominion of comet aficionados in the Southern Hemisphere, but that is about to change. As the comet continues its well-understood and safe passage through the inner-solar system, its celestial splendor will be lost to those in the Southern Hemisphere, but found by those up north.
After imaging during the holidays, NASA’s Mars rover Curiosity resumed driving Jan. 3 and pulled within arm’s reach of a sinuous rock feature called “Snake River.”
Snake River is a thin curving line of darker rock cutting through flatter rocks and jutting above sand. Curiosity’s science team plans to get a closer look at it before proceeding to other nearby rocks.
“It’s one piece of the puzzle,” said the mission’s project scientist, John Grotzinger of the California Institute of Technology in Pasadena. “It has a crosscutting relationship to the surrounding rock and appears to have formed after the deposition of the layer that it transects.”
The drive during the mission’s 147th Martian day, or sol, on the Red Planet took Curiosity about 10 feet (3 meters) northwestward and brought the mission’s total driving distance to 2,303 feet (702 meters). The rover is within a shallow depression called “Yellowknife Bay,” which is a flatter and lighter-toned type of terrain from what the mission crossed during its first four months inside Gale Crater.
During a holiday break for the rover team, Curiosity stayed at a location within Yellowknife Bay from which the rover took images of its surroundings. The team is evaluating possible first targets for use of Curiosity’s hammering drill in coming weeks. The drill will collect powdered samples from the interior of rocks for analysis by instruments inside the rover.
“We had no surprises over the holidays,” said the mission’s project manager, Richard Cook of NASA’s Jet Propulsion Laboratory, Pasadena. “Now, Curiosity is back on the move. The area the rover is in looks good for our first drilling target.”
NASA’s Mars Science Laboratory Project is using Curiosity to assess whether areas inside Gale Crater ever offered a habitable environment for microbes. JPL, a division of Caltech, manages the project for NASA’s Science Mission Directorate in Washington.
The rover Curiosity successfully landed on Mars on August 6, flawlessly executing the improbable acrobatics of touching down on the Red Planet intact. President Obama congratulated Elachi and colleagues on the achievement and complimented them on the coolness of “Mohawk Guy” on August 13. Curiosity also completed its test drive and passed many initial inspections.
This week, Elachi visited Atlanta’s Georgia Institute of Technology, where he signed an agreement with the school that will involve exchanging faculty, inviting students to JPL, and other collaborations.
Elachi sat down with CNN’s Elizabeth Landau and Sophia Dengo for a chat about the future of space exploration. Here’s an edited transcript:
CNN: Curiosity’s on Mars now. What’s next?
NASA Jet Propulsion Laboratory Director Charles Elachi: Clearly Curiosity showed the excitement of the public about doing these kind of things.
That’s one step in a long-term Mars exploration and planetary exploration program, which first would lead to bringing samples back. In a sense we are building the capability step by step.
If you go back 15 years, the first time we landed a rover on Mars it was called Sojourner. And it was about (the size of) a shoe box. So, just in this period, we moved from a shoebox to building a car-sized, one-ton rover landing on Mars, and being effectively a chemistry lab on wheels.
And the objective is to do detailed analyses of rocks on Mars to see if there are any organic materials, the ultimate thing we want to see is: Was Mars ever habitable? Did life evolve on Mars? Why it did or why it did not, and how does that compare to Earth?
In a sense you are doing an experiment of comparing those two planets which formed roughly at the same time… but they ended up going in different ways, and the question is: Why did that happen?
In a show of technological wizardry, the robotic explorer Curiosity blazed through the pink skies of Mars, steering itself to a gentle landing inside a giant crater for the most ambitious dig yet into the red planet’s past.
Cheers and applause echoed through the NASA Jet Propulsion Laboratory late Sunday after the most high-tech interplanetary rover ever built signaled it had survived a harrowing plunge through the thin Mars atmosphere.
“Touchdown confirmed,” said engineer Allen Chen. “We’re safe on Mars.”