Contrary to recent headlines — and a talk by actor Arnold Schwarzenegger at the United Nations Paris Climate Change Conference — eating a vegetarian diet could contribute to climate change. In fact, according to new research from Carnegie Mellon University, following the USDA recommendations to consume more fruits, vegetables, dairy and seafood is more harmful to the environment because those foods have relatively high resource uses and greenhouse gas (GHG) emissions per calorie. 

Climate negotiators meeting here in Paris have achieved a deal that could change the world. Conference chair and French foreign minister Laurent Fabius crowed that he had presided over a "historical turning point." Even when the hype has died down, that may turn out to be true. Even climate scientists who on Friday had sharply criticized an earlier draft of the text were convinced.  

The Paris Agreement commits the world to capping global warming to "well below 2 degrees Celsius above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 degrees C." To achieve that, it requires the world to "reach global peaking of greenhouse gas emissions as soon as possible" and "to undertake rapid reductions thereafter, in accordance with best available science." 

Scientists are studying past changes in sea level in order to make accurate future predictions of this consequence of climate change, and they're looking down to Earth's core to do so. "In order to fully understand the sea-level change that has occurred in the past century, we need to understand the dynamics of the flow in Earth's core" says Mathieu Dumberry, a professor in physics at the University of Alberta.

The connection is through the change in the speed of Earth's rotation. Melt water from glaciers not only causes sea-level rise, but also shifts mass from the pole to the equator, which slows down the rotation. (Picture the Earth as a spinning figure skater. The skater moves his or her arms in to spin more quickly or out to slow down.) The gravity pull from the Moon also contributes to the slow down, acting a little like a leaver break. However, the combination of these effects is not enough to explain the observations of the slowing down of Earth's rotation: a contribution from Earth's core must be added.

The ongoing El Niño weather pattern in the Asia and Pacific is likely to be one of the strongest since 1998 and will continue into early 2016, according to a new United Nations advisory, which urges regional cooperation for early warning, in-season mitigation, and long-term adaptation strategies to curb climate risk.

“The impact of the 2015-2016 El Niño could be even more severe in certain locations, such as the uplands of Cambodia, central and southern India, eastern Indonesia, the central and southern Philippines, central and northeast Thailand...” stated the Third Advisory Note on El Niño issued jointly by the UN Economic and Social Commission for Asia and the Pacific (ESCAP) and the Regional Integrated Multi-Hazard Early Warning System for Africa and Asia (RIMES).

Lawrence Livermore researchers and collaborators have found that most climate models overestimate the increase in global precipitation due to climate change.

Specifically, the team looked at 25 models and found they underestimate the increase in absorption of sunlight by water vapor as the atmosphere becomes moister, and therefore overestimate increases in global precipitation.

The team found global precipitation increase per degree of global warming at the end of the 21st century may be about 40 percent smaller than what the models, on average, currently predict.

Is Paris the beginning of the end for coal? Coal burning is declining fast in both of the world's two largest carbon dioxide emitters, China and the the United States, with resulting declines in the emissions of both countries. The fuel looks incompatible with a world that warms by no more than two degrees Celsius, bringing calls for its rapid phaseout as the world is "decarbonized." 

But, with or without a deal here in Paris later this week, will the calls be heeded? Has the demise of King Coal been greatly exaggerated?  

In the U.S., "coal has gone from boom to bust," says Michael Brune, executive director of the Sierra Club. The black stuff's share of electricity generation has sunk from 53 percent to 35 percent in just five years.
 

Clouds can increase warming in the changing Arctic region more than scientists expected, by delivering an unexpected double-whammy to the climate system, according to a new study by researchers at NOAA, the University of Colorado Boulder and colleagues.

Clouds can increase warming in the changing Arctic region more than scientists expected, by delivering an unexpected double-whammy to the climate system, according to a new study by researchers at NOAA, the University of Colorado Boulder and colleagues.

"Two things are happening," said study co-author William D'Andrea, a paleoclimatologist at Columbia University's Lamont-Doherty Earth Observatory. "One is you have a very gradual decrease in the amount of sunlight hitting high latitudes in the summer. If that were the only thing happening, we would expect these glaciers to very slowly be creeping forward, forward, forward. But then we come along and start burning fossil fuels and adding carbon dioxide to the atmosphere, and glaciers that would still be growing start to melt back because summer temperatures are warmer."

Glaciers are dynamic and heavy. As a glacier moves, it grinds the bedrock beneath, creating silt that the glacier's meltwater washes into the lake below. The larger the glacier, the more bedrock it grinds away. Scientists can take sediment cores from the bottom of glacier-fed lakes to see how much silt and organic material settled over time, along with other indicators of a changing climate. They can then use radiocarbon dating to determine when more or less silt was deposited.

As representatives from more than 190 countries convene in France for the second week to address ways to slow global warming, an MIT-led team has published a paper outlining a set of options for incorporating equity considerations in a national Emissions Trading System (ETS) for China that could reduce carbon emissions while minimizing economic impact on poorer or less-developed regions.

The paper, “Equity and Emission Trading in China,” published in the journal Climatic Change, outlines a sophisticated menu aimed at Chinese policymakers showing how the burden of reducing carbon emissions could be shared or divided across the country’s provinces under a market-based carbon pricing system.

“Emission trading systems have been shown to be highly effective when they are allowed to work, but one of the toughest challenges involves how to distribute the cost,” said lead author Valerie Karplus, Assistant Professor of Global Economics and Management at the MIT Sloan School of Management. “We compare alternative schemes for allocating emissions rights that can effectively de-couple who pays for reductions from where the reductions actually occur.”