Natural fluctuations specifically related to the Interdecadal Pacific Oscillation (IPO) are responsible for the increased growth of Antarctic sea ice, according to a new study in the journal Nature Geoscience. A negative shift in the IPO has caused cooler-than-average sea surface temperatures in the Eastern Pacific, allowing Antarctic sea ice to expand since 2000.
"The climate we experience during any given decade is some combination of naturally occurring variability and the planet's response to increasing greenhouse gases," said National Center for Atmospheric Research scientist Gerald Meehl, lead author of the study. "It's never all one or the other, but the combination, that is important to understand."
But what's new in the latest study, writes Chris Mooney in The Washington Post, "is the suggestion that this negative IPO phase had consequences that stretched all the way to the Southern Ocean waters surrounding Antarctica--and that this, in turn, explains why most climate models didn't predict the observed growth of Antarctic sea ice."
Study researchers suspect that the IPO began switching to a positive phase in 2014 and that ice in the region may shrink in the next decade.
Study Points to Human Influence on Changes in Earth's Biggest Body of Warm Water
A study in Science Advances has provided the first quantitative attribution of human influences on and natural contributions to warming of the Indo-Pacific warm pool (IPWP), Earth's largest region of warm sea surface temperatures and one "fundamental to global atmospheric circulation and the hydrological cycle."
To "fingerprint" anthropogenic forcings and natural causes of substantial IPWP warming and expansion, researchers at Pohang University of Science and Technology and their international colleagues paired observations with multiple climate model simulations integrated with and without human influences. They found that the IPWP had warmed by 0.3 Celsius and increased in size by about a third over the last 60 years primarily due to an increase in human-made greenhouse gases.
About 12 to 18 percent of the warming has been due to natural variability in the ocean, but the remaining portion is due to the greenhouse gas increase, according to study co-author Seung-Ki Min of Pohang University in South Korea.
"We have more energy available from the hotter ocean," said Min. "That means the atmosphere will be enhanced to transport more energy from the tropical ocean to the high latitude zone."
The findings indicate that future ocean warming could increase storm activity over East Asia and strengthen monsoons over South Asia.
"This wasn't entirely surprising. We've long suspected climate change to be behind the changes, but no one had yet proven it," said Evan Weller, lead author, noting that what was surprising is that the western portion of the pool, near India, is expanding more than the eastern part in the Pacific. "We don't really know why. We'll try to figure that out next."
Report: United States Is Oil Reserves Leader
The United States holds the largest share of the world's oil reserves--264 billion barrels to Russia's 256 billion and Saudi Arabia's 212 billion, according to Rystad Energy, a Norwegian industry research group that tracks proved and probable reserves, discoveries and undiscovered fields. More than 50 percent of remaining oil reserves, it claims, are unconventional shale oil. Texas alone holds more than 60 billion barrels of shale oil.
On the basis of a three-year analysis of 60,000 fields worldwide, the group estimates global reserves to be 2,092 billion barrels--roughly 70 times the current production rate of some 30 billion barrels of crude oil per year.
"This data confirms that there is a relatively limited amount of recoverable oil left on the planet," the report says. "With the global car-park possibly doubling from 1 billion to 2 billion cars over the next 30 years, it becomes very clear that oil alone cannot satisfy the growing need for individual transport."
The Climate Post offers a rundown of the week in climate and energy news. It is produced each Thursday by Duke University's Nicholas Institute for Environmental Policy Solutions.