In ancient Earth history, the sun burned as much as 30 percent dimmer than it does now. Theoretically that should have encased the planet in ice, but there is geologic evidence for rivers and ocean sediments between 2 billion and 4 billion years ago.
Scientists have speculated that temperatures warm enough to maintain liquid water were the result of a much thicker atmosphere, high concentrations of greenhouse gases or a combination of the two. (more…)
Mesquite trees and woody shrubs are better adapted than grasslands to a Southwestern climate predicted to shift toward higher temperatures and greater variability in rainfall, UA ecologists have discovered.
As the desert Southwest becomes hotter and drier, semi-arid grasslands are slowly being replaced by a landscape dominated by mesquite trees, such as Prosopis velutina, and other woody shrubs, a team of University of Arizona researchers has found.
In a “leaf-to-landscape” approach, the team combined physiological experiments on individual plants and measurements across entire ecosystems to quantify how well grasslands, compared to mesquite trees and woody shrubs, cope with heat and water stress across seasonal precipitation periods. (more…)
COLUMBIA, Mo. – For nearly a year, the Midwest and southwest United States have experienced drought and warmer than normal conditions. A University of Missouri expert is predicting no relief, as he expects drought and hot conditions to continue this summer.
“I expect one of two scenarios to play out; the first is a continued La Nina climate pattern to affect our weather this summer,” said Tony Lupo, professor and chair of the Department of Atmospheric Science in the School of Natural Resources. “This will lead to a drought and above average heat throughout the Midwest from Texas to Iowa, where farmers with parched fields can least afford dry conditions. However, it is also possible that a new El Nino pattern could develop this fall. While I don’t see this happening, it would bring more favorable temperatures and precipitation patterns to the Midwest.” (more…)
When Sifrhippus sandae, the earliest known horse, first appeared in the forests of North America more than 50 million years ago, it would not have been mistaken for a Clydesdale.
It weighed in at around 12 pounds–and it was destined to get much smaller over the ensuing millennia.
Sifrhippus lived during the Paleocene-Eocene Thermal Maximum (PETM), a 175,000-year interval of time some 56 million years ago in which average global temperatures rose by about 10 degrees Fahrenheit. (more…)
USGS scientists and academic colleagues investigated how California’s interconnected San Francisco Bay and Sacramento-San Joaquin Delta (the Bay-Delta system) is expected to change from 2010 to 2099 in response to both fast and moderate climate warming scenarios. Results indicate that this area will feel impacts of global climate change in the next century with shifts in its biological communities, rising sea level, and modified water supplies.
“The protection of California’s Bay-Delta system will continue to be a top priority for maintaining the state’s agricultural economy, water security to tens of millions of users, and essential habitat to a valuable ecosystem,” said USGS Director Marcia McNutt. “This new USGS research complements ongoing initiatives to conserve the Bay-Delta by providing sound scientific understanding for managing this valuable system such that it continues to provide the services we need in the face of climate uncertainty.” (more…)
*Computer simulations of global climate lead to new conclusions*
Earth’s deep oceans may absorb enough heat at times to flatten the rate of global warming for periods of as long as a decade–even in the midst of longer-term warming. This according to a new analysis led by scientists at the National Center for Atmospheric Research (NCAR).
The study, based on computer simulations of global climate, points to ocean layers deeper than 1,000 feet as the main location of the “missing heat” during periods such as the past decade when global air temperatures showed little trend. (more…)
*New computer modeling study, led by a Berkeley Lab scientist, could help revise understanding of permafrost’s role in global warming*
Billions of tons of carbon trapped in high-latitude permafrost may be released into the atmosphere by the end of this century as the Earth’s climate changes, further accelerating global warming, a new computer modeling study indicates.
The study also found that soil in high-latitude regions could shift from being a sink to a source of carbon dioxide by the end of the 21st century as the soil warms in response to climate change. (more…)
Taking another major step in sleuthing the 2010 Deepwater Horizon oil spill, a research team led by the Woods Hole Oceanographic Institution (WHOI) has determined what chemicals were contained in a deep, hydrocarbon-containing plume at least 22 miles long that WHOI scientists mapped and sampled last summer in the Gulf of Mexico, a residue of the Deepwater Horizon oil spill. Moreover, they have taken a big step in explaining why some chemicals, but not others, made their way into the plume.
The findings, published this week in the online edition of the Proceedings of the National Academy of Sciences, “help explain and shed light on the plume formation and verify much of what we thought about the plume’s composition,” said WHOI chemist Christopher Reddy, lead author of the study. The data “provide compelling evidence” that the oil component of the plume sampled in June 2010 essentially comprised benzene, toluene, ethybenzene, and total xylenes—together, called BTEX—at concentrations of about 70 micrograms per liter, the researchers reported. (more…)
