This four-part post originally appeared on the Net Impact Boston blog.

• Part 1: COP21: The UN Climate Change Conference
• Part 2: COP21: Why This Year is Different
• Part 3: My Impressions from COP21
• Part 4: What’s In the Paris Agreement?

In my previous post I gave some background and history of the Conferences of the Parties (COPs), the annual UN Climate Change Conference. While this is the first COP I’ve attended, there’s ample evidence that “this year is different”. Here are a few reasons why:

• First, most people say that they’re realistically hoping for an accord, not a protocol. That means it likely won’t be legally binding, and thus won’t need to be ratified by the US Congress (sorry for the name-dropping, but I had a chat with French ambassador to the US about this, and he told me that the US Congress was the main reason why they weren’t trying for a legally binding agreement).
• To keep everyone still accountable, countries submitted Intended Nationally Determined Contributions (INDCs) to spell out their reduction targets. Many countries submitted these, which nearly all emissions (see leading graphic). The US was among the first to submit (thanks Obama… no, seriously!) and committed to a 26-28 percent cut against 2005 emissions levels by 2025.
• The US and China are finally committed. While our Congress has still maintained they won’t ratify a legally binding accord, the US and China announced a landmark climate agreement late last year, setting the stage for their INDC commitments. (President Xi of China said that China will peak its emissions by 2030, then start reducing them, if not earlier; and committed to 20% of its energy coming from zero-emissions sources by 2030.)
• Europe is already committed to legally binding 40% cuts.
• A major economic sticking point at COPs past, the rich countries have finally agreed to subsidize poor countries’ leapfrogging of cheap, dirty technologies into cleaner ones. In 2009, the developed nations agreed to send $100 billion each year to the developing nations.
• The business community is here in force, such as the World Business Council on Sustainable Development (WBCSD), sending negotiators a clear message that we support a climate accord. (You can watch the full livecast of the WBCSD’s council meeting here.) Even ExxonMobil is calling for a carbon tax, as Ken Cohen (who keynoted the 2014 Net Impact conference) lays out in this blog post.
• The public here—both Parisians and visitors—are as vocal as ever, from indigenous tribes from affected island countries, to Americans affected by fracking, to Asian citizens blighted with thick urban pollution.

In the next post I’ll give some of my impressions on attending some events at COP21 — and on these last two points in particular, the presence of both the business community and the public.