Gauging the trickle-down effects of high-level international policy is never easy. That's especially true with a hulking global issue such as climate change, which consistently has been pushed down the laundry list of challenges facing the planet.

This week, however, is poised to provide a notable bookend on the COP21 United Nations climate talks held in Paris in December, which saw delegates from 196 countries agree to work toward limiting global average temperature increases to "well below" 2 degrees Celsius. Representatives from 155 of those countries are expected to sign the agreement in New York City and make it official Friday, which also happens to be Earth Day.

But what about the five months that have passed since the closing gavel?

The real work of determining how to get anywhere near the 2-degree target — with 1.5 C being the threshold many advocates say will unleash devastation in vulnerable island and low-lying nations — ultimately will come down to individual national governments, businesses and members of civil society.

While much of the heavy lifting remains to be done, several significant indicators suggest that expediting clean energy deployment, bringing the private sector on board with climate action and hashing out who pays for climate adaptation (finally) are starring on the global stage.

1. Clean energy investment goes global

A primary sticking point heading into the Paris talks was how to balance the priorities of wealthy industrialized nations and poorer developing countries, the latter of which are expected to bear the brunt of accelerating climate impacts.

One encouraging sign: Clean energy investment data released last month by Bloomberg New Energy Finance shows that the biggest growth in support for renewable power came in emerging economies such as China ($102.9 billion), India ($10.2 billion) and South Africa ($4.5 billion). The U.S., despite its complicated climate politics, did also see a 19-percent increase in funding.

Whether those figures are enough to truly start transitioning the world away from fossil fuels is still up for debate. Bloomberg found that European investment levels fell 21 percent to $48.8 billion. It is somewhat disconcerting that wealthy countries theoretically better positioned to make bigger investments are being outpaced.

2. Big companies back the Clean Power Plan

Apple, Google, Microsoft, Amazon, Ikea, Mars — no, it's not a list of the world's most visible companies. It's the roster of businesses that earlier this month signed on to two separate Amici Curiae (PDF) briefs (PDF) filed in U.S. Circuit courts in support of the Environmental Protection Agency’s Clean Power Plan.

Given that the intransigent partisan politics of the U.S. have been a big concern in the context of the global Paris Agreement, public pressure from the private sector — an act of policy advocacy that goes well beyond self-serving sustainability marketing — could be a game changer. For now, it's up to the U.S. courts to rule on the Obama administration's attempt to meaningfully reduce industrial emissions.

One interesting question in the meantime is whether businesses will drive a stake in the ground when it comes to state obstructionism to renewable energy, as they have done in calling off state investments due to regressive social policies.

A logistical issue that also remains to be solved for even climate-friendly companies: the extremely high financial barrier that still exists for blockbuster utility-scale renewable energy projects, such as the $848 million solar investment Apple announced last year.

3. Obama proposes a $10-a-barrel tax on oil

Another surprise entry in the category of post-Paris actions in the U.S. was President Barack Obama's proposal for a $10-a-barrel tax on oil as part of clean transportation initiative unveiled in February.

The move, which predictably faced immediate backlash, came as broader debates over the future of carbon pricing broke out in jurisdictions ranging from the states of Oregon and New York to countries including China and Mexico.

Still, it's important to keep in mind that the White House proposal fits into a long history of mixed messages on fossil fuels, the most notable being continued taxpayer subsidies of the oil and gas industries.

4. A new chapter in the coal chronicles

A week ago, the biggest coal company in the world filed for Chapter 11 bankruptcy. The moment was a dramatic one for a major U.S. company, but one that wasn't altogether shocking.

The bankruptcy of Peabody Energy is just one vivid example of the overall decline of the coal industry, which has been at the center of debate over what to do about the prospect of large-scale "stranded assets" that could necessitate trillions of dollars worth of writedowns from fossil fuel companies in the event of stricter carbon regulations.

With gas prices just starting to climb again, it remains to be seen whether other energy incumbents will see a similar twist in fate. On the bright side: the largely untapped opportunity to retrain former coal workers and repurpose former coal infrastructure in the pursuit of new clean energy systems.

5. Cities and states aim to go 100 percent renewable

The rise of "sub-national" climate action — sustainability-wonk-speak for climate change responses at the state and city level — is another long-heralded trend bolstered by several big developments in the aftermath of the Paris talks.

In mid-2015, Hawaii became the first U.S. state to establish a 100 percent renewable aim for 2045. Just before the New Year, San Diego — the eighth largest city in the country — set a goal to complete a shift to clean power by 2035.

Watch the fine print of these goals and others likely to emerge in the coming months to see how different jurisdictions approach issues such as natural gas as a less-than-ideal bridge fuel, as well as who will win ownership of large new energy installations, and how sectors with large carbon footprints (à la transportation) are treated by policymakers.