Roughly six months before international leaders meet in Paris for a United Nations climate change conference, U.S. states and foreign nations are stepping forward with climate commitments. Canada, on Friday, pledged to cut its greenhouse gas emissions 30 percent below 2005 levels by 2030.
California is joining a climate agreement with eight foreign nations and four states that aims to keep the world's average temperature from rising another 2 degrees Celsius. All signatories of the Under 2 MOU commit to either reduce greenhouse gas emissions 80 to 95 percent below 1990 levels by 2050 or achieve a per capita annual emissions target of less than 2 metric tons by 2050.
"This global challenge requires bold action on the part of governments everywhere," said California Gov. Jerry Brown, who urged Under 2 MOU to serve as a template for Paris. "It's time to be decisive. It's time to act."
The signatories of the non-binding agreement include California; Vermont; Oregon; Washington; Wales, United Kingdom; Acre, Brazil; Baden-Württemberg, Germany; Baja California, Mexico; Catalonia, Spain; Jalisco, Mexico; British Columbia, Canada; and Ontario, Canada.
India and China--among the world's largest emitters of greenhouse gases--also committed to working together in advance of Paris negotiations. Neither made formal commitments, indicating they would submit their official plans "as early as possible" and "well before" the December conference. In a statement, both urged "developed countries to raise their pre-2020 emission reduction targets and honor their commitment to provide $100 billion per year by 2020 to developing countries."
Studies Examine Cause of Warming
A study published in Environmental Research Letters presents a 1958-to-2012 temperature and wind dataset of the upper troposphere (Earth's atmosphere) as clear evidence of emissions-induced climate change.
"Using more recent data and better analysis methods we have been able to re-examine the global weather balloon network, known as radiosondes, and have found clear indications of warming in the upper troposphere," said lead author and Australian Research Council Centre of Excellence for Climate System Science Chief Investigator Steve Sherwood.
The study helps answer questions about temperature variations throughout different parts of the atmosphere by developing a new method to account for natural variability, long-term trends, and instruments in the temperature measurement--revealing real temperature changes as opposed to artificial changes generated by alterations in data collection methods. It finds that tropospheric warming has continued as predicted, and it confirms the expectation that as global warming progresses, the troposphere will warm faster than the Earth surface. In fact, tropospheric temperature is rising roughly 80 percent faster than Earth's surface temperature (within the tropics region).
"Our data do not show any slowdown of tropical atmospheric warming since 1998/99, an interesting finding that deserves further scrutiny using other datasets," said the study authors.
Another study, published Monday in Nature Geoscience, sheds yet more light on "missing" heat--or the failure of global surface temperatures to rise as quickly as expected since 1999. Scientists have accounted for the so-called global warming pause by suggesting that there's been a transfer of heat from the tropical Pacific into the Indian Ocean. It turns out that heat in the Pacific moved with an ocean current strengthened by unusually high trade winds into the Indian Ocean, which is now home to 70 percent of all heat taken up by global oceans during the past decade.
"This is a really important study as it resolves how Pacific Ocean variability has led to the warming slowdown without storing excess ocean heat locally," said Matthew England, a professor at the University of New South Wales. "This resolves a long-standing debate about how the Pacific has led to a warming slowdown when total heat content in that basin has not changed significantly."
Others suggest the story is more complex. Real-world measurements of ocean heat content obtained through the Argo program--which measures temperature and salinity through free-drifting floats--suggest that some of the missing ocean heat might be present at depths between 700 and 1,400 meters, in a region of the ocean south of the 30th parallel; the study authors focused on the Indian Ocean north of the 34th parallel and used climate models to validate observations.
Obama: Climate Change Endangers National Security
The warming planet poses an immediate risk to the United States, and urgent action is needed to combat climate change as a national security imperative, President Obama told the U.S. Coast Guard Academy during a commencement address.
"Here at the academy, climate change--understanding the science and the consequences--is part of the curriculum, and rightly so, because it will affect everything you do in your careers," said Obama. "As America's maritime guardian, you've pledged to remain always ... ready for all threats, and climate change is one of those most severe threats. And so we need to act, and we must act now.... [A]nything less is negligence. It is a dereliction of duty."
He noted that droughts and other conditions will pose new challenges for military bases and training areas, that rising oceans will threaten the U.S. economy, and that an increase in natural disasters will result in humanitarian crises.
The U.S. committed to reducing carbon emissions 28 percent by 2025--and Obama is expected to travel to Paris in December to explore whether a global climate treaty to reduce greenhouse gases can be reached.
"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.