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Cities in the World’s Top Greenhouse Gas Emitters Announce Stronge

Cities in China and the United States pledged to take ambitious steps to address climate change at the state and local level in the U.S.-China Climate Leaders Declaration this week.

In China, 11 cities will peak greenhouse gas emissions—some as early as 2020—to eliminate nearly 25 percent of China’s urban total carbon pollution. In the United States, pledges from 18 cities range from carbon neutrality to carbon reduction. Seattle plans to be carbon neutral by 2050. Houston commits to a 42 percent reduction by 2016 and to 80 percent by 2050 (based on a 2007 baseline). Los Angeles aims for reductions of 45 percent by 2025, 60 percent by 2030 and 80 percent by 2050 (based on a 1990 baseline).

In addition to these greenhouse gas targets, the declaration also conveys intentions to regularly report emissions and to establish climate plans to reduce them.

“The commitments that the Chinese and American cities are taking … are a very important component of our broader efforts to deepen climate cooperation and to show that … the two largest emitters in the world are taking seriously our obligation to meet the ambitious goals that we set out last year,” said Brian Deese, a senior adviser to President Obama. He noted that the declaration builds on a climate change deal reached in November by Obama and Chinese President Xi Jinping last year. That deal called for the United States to lower greenhouse gas emissions as much as 28 percent below 2005 levels by 2025. China agreed to peak emissions by 2030.

The pledges come a little more than two months before nations gather for international climate negotiations Nov. 30 to Dec. 11 in Paris—a meeting intended to produce a deal that would commit all nations to reducing greenhouse gas emissions. But the 62 climate commitments leading up to the COP—may not be enough to keep global warming to the 2-degree Celsius threshold recommended by the United Nations, said U.N. Executive Secretary Christiana Figueres. Her “guestimate” of the pledges, which cover approximately 70 percent of global emissions, is that they would equate to 3-degrees Celsius of warming, compared with pre-industrial levels.

Met Office Report Predicts Warmer Times to Come

The same week researchers released a study finding that the snowpack in California’s Sierra Nevada has shrunk to a 500-year low, the U.K. government agency that studies global weather patterns released a peer-reviewed report suggesting the world is moving into a warming trend.

Several global changes, the Met Office says, are occurring simultaneously to cause the change. One is El Nino—warm bands of ocean water in the central and east-central Pacific—which is expected to occur this year and to be particularly strong.

“We know natural patterns contribute to global temperature in any given year, but the very warm temperatures so far this year indicate the continued impact of increasing greenhouse gases,” said Stephen Belcher, head of the Met Office Hadley Centre. “With the potential that next year could be similarly warm, it’s clear that our climate continues to change.”

Southern Ocean’s Carbon-Storing Capacity Increases, but for How Long?

A new study in Science finds that the Southern Ocean carbon sink has been reinvigorated, helping limit climate change. Its uptake of greenhouse gases stalled in the 1980s but roughly doubled to 1.2 billion tonnes—equivalent to the European Union’s annual man-made greenhouse gas emissions—between 2002 and 2011.

“It’s good news, for the moment,” Nicolas Gruber, an author of the study at Swiss university ETH Zurich, told Reuters. But he said it was unclear how long the higher rate of absorption by the Southern Ocean, the strongest ocean region for mopping up carbon, would last. Moreover, increased carbon dioxide could be bad news for marine life because, once absorbed in water, some of it becomes carbonic acid, which disrupt shellfishes’ ability to grow their protective shells.

Gruber and his colleagues analyzed 2.6 million measurements of carbon dioxide (CO2) concentration in the surface waters of the Antarctic Ocean made by ships over three decades. They concluded that the ocean’s carbon uptake fluctuates strongly, rather than increasing monotonically in response to the growing atmospheric CO2 concentration. Wind and temperature changes appear to drive these shifts, which are linked to low-pressure systems in the Pacific and high pressure over the Atlantic section of the Southern Ocean.

Peter Landschützer, a postdoctoral researcher involved in the study, said existing models can’t predict how patterns will change in the future, “so it is very critical to continue measuring the surface ocean CO2 concentrations in the Southern Ocean.” Currently, long-term datasets are the only reliable means for determining the evolution of the ocean’s carbon-storing capacity.

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.