At the 2014 United Nations Climate Change Conference twentieth Conference of the Parties, known as COP20, in Lima, Peru, delegates from more than 190 nations are hashing out details of an international agreement to limit greenhouse gas emissions and curb permanent damage caused by global warming. Those details will set the stage for next December's UN meeting in Paris, where negotiators are aiming to finalize a global climate change deal.

Diplomats and longtime observers of the talks say there is rising optimism that negotiators will secure a deal committing all countries to take action against climate change. "I have never felt as optimistic as I have now," said Tony de Brum, the foreign minister of the Marshall Islands, which are sinking as sea levels rise in the Pacific. "There is an upbeat feeling on the part of everyone that first of all there is an opportunity here and that secondly, we cannot miss it."

What's driving the momentum?

Last month, the United States and China, the world's top emitters of greenhouse gases, announced an agreement to slash their emissions. In October, the European Union pledged to reduce its emissions 40 percent, compared with 1990 levels, by 2030. And, the UN's Green Climate Fund, which helps developing countries address climate change, is on track to meet its ten-billion-dollar initial target.

However, researchers note that drastic cuts are needed to achieve the overall goal of the international community: limiting global warming to 2 degrees Celsius above pre-industrial levels. Meeting that goal means emissions must be slashed 40 to 70 percent by 2050.

"We're in far better shape a year ahead of Paris than at any stage leading up to Copenhagen," where world leaders tried but failed to reach a climate deal in 2009, says Elliot Diringer, executive vice president of the Center for Climate and Energy Solutions.

EPA Closes Public Comment Period on Proposed Clean Power Plan

The U.S. Environmental Protection Agency (EPA) has officially closed the public comment period on its proposed Clean Power Plan (CPP), having collected more than 1.6 million comments from legislators, industry, environmental advocates and the general public.

The EPA had extended the comment period by 45 days, to December 1, to give the public additional time to understand and analyze the plan, which aims to cut carbon emissions from power plants across the country by approximately 30 percent by 2030.

"We've heard that the carbon reductions targets we proposed are too tough and we've heard that they're not tough enough," said EPA Air and Radiation Administrator Janet McCabe in an official EPA blog. "What we know for sure is that people care about this issue and we know we have a lot to consider as we work toward a final rule."

Particularly contentious are the CPP's state-specific emissions goals. According to the Edison Electric Institute, the association representing all U.S. investor-owned utilities, and other industry leadership, the goals could cause power companies to install costly upgrades that would diminish electricity affordability. Meanwhile, environmental groups such as the Natural Resources Defense Council say that falling solar and wind power prices and advancements in efficiency standards could allow the EPA to require steeper emissions cuts sooner--by 2020.

The EPA is scheduled to finalize the proposed rule by June 2015.

Mapping Low-Carbon Investments in the United States

A recent report issued by the Deep Decarbonization Pathways Project (DDPP) says the United States can use existing or soon-to-be-available technologies to reduce greenhouse gas emissions by 80 percent by 2050--the trajectory on which the recent U.S. agreement with China would put the country, according to Special Envoy for Climate Change Todd Stern.

According to the DDPP report, decarbonization in the United States requires

:

Boosting energy efficiency in buildings, cars and industrial facilities

Cutting the carbon from electricity and other fuels

Swapping high-carbon fuels with low-carbon alternatives

"If you bet on America's ability to develop and commercialize new technologies, then the net cost of transforming the energy system could be very low, even negative, when you take fuel savings into account," said

, chief scientist at San Francisco-based consulting firm Energy and Environmental Economics, Inc. and the report's lead author.

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.