MIAMI — The message on the monitors was clear: Nine images from satellites circling the top of the globe, each showing summer ice extent for a different year from 2002 to 2011, yet none coming close to the historic average.
Then the screens flickered, and up came nine snapshots of a dying Aral Sea from 2000 to 2009, the blue-green waters never wetting more than a portion of the dry lakebed.
Another flicker and all nine monitors showed a single image of the globe. Superimposed was time-elapsed imagery of regional nitrous oxide emissions: White-hot over China and much of Europe, big bilious clouds washing over eastern North America and out over the Atlantic.
The images, displayed during the Society of Environmental Journalists meeting here last week, came courtesy of an international fleet of increasingly sophisticated satellites orbiting the planet. Data they beam to the ground provide graphic evidence to scientists and the public of humanity's activity — and the impacts of those actions on the planet.
"There are days when - because we're looking at all these data sets - we're seeing things before the scientists," said Mike Carlowicz, editor of the NASA Earth Observatory, which is posting and archiving a vast array of satellite imagery for the public. "Some of it is showing how beautiful the planet is. But some of it is giving people a new way of looking at something they already know about. And some of it is just 'Gee whiz.' "
The satellites have opened new horizons in our understanding of planetary science. They've also proved invaluable in the wake of human and natural disasters, helping guide responses to the grounding of the New Zealand oil tanker and flooding in Thailand, among others, according to Hans Gruber, director of the Center for Southeastern Tropical Advanced Remote Sensing.
But the fleet is aging, and replacements are having trouble getting off the ground. A picture scientists and the public alike have come to expect risks growing clouded.
In March a $424 million satellite designed to study how the sun and tiny aerosol particles affect the atmosphere crashed into the Pacific, endangering NASA's 33-year record used to estimate global warming from greenhouse gases.
Earlier in the year a $1 billion satellite tasked with improving the accuracy of computer models to predict climate change fell victim to budget cutting efforts. Combined, the two delivered a considerable blow to what scientists describe as an already shaky and under-funded remote-sensing program.
"A lot of the NASA satellites are aging," Gruber said. "There's not a fast-enough replacing of some of these sensors."
A new generation of entrepreneurs and students, however, offer hope. They are designing and launching miniature satellites, dubbed "CubeSats," that have a volume no bigger than a soda bottle and that weigh little more than a typical SLR camera.
CubeSats today are hampered by limited capacity and remain for now little more than teaching aids. But the field is seeing tremendous growth, and the technology is leading to a democratization of space and atmospheric science that offers tremendous potential, said Andres Alfonso, co-founder of Sequoia Space, a Colombia-based CubeSat development company.
The satellites, for instance, can be built for between $60,000 and $200,000 and launched for as little as $4,000, he said. Universities and companies throughout South America and Africa are racing to design and launch them.
"We will one day see small satellites doing the tasks of the huge satellites."
Maybe so, acknowledged Steve Platnick, senior project manager for NASA's Earth Observing System.
But for now most climate measurements require "accuracies that are incredible," he cautioned. And that means scientists need heavy, sophisticated, expensive-to-launch machines.
"If there are cheaper, simpler ways to get to space, it certainly opens new avenues," he said. "But a lot of satellites have to be large and massive because of the resolution required."
And that resolution is what's leading to new insights about the planet and, perhaps, will spur action. NASA, for instance, highlights daily one photo of the Earth taken from a satellites' vantage. It also groups multiple images over time of various global hotspots - burn recovery in Yellowstone National Park, mountaintop mining in West Virginia, the urbanization of Dubai.
"We're not advocates," said NASA's Carlowicz, staring at nine images showing increasing deforestation in Brazil. "But it's hard not to look at some of this and not be moved."
"Whatever your response is to this, you need to know it's happening."