What is the Paris climate accord?

United States President Donald Trump is set to make a major announcement about his country's involvement in the Paris climate accord. 

If you do not know by now, here's what the Paris climate accord is:

What it is

Officially known as the Paris Agreement, it was adopted Dec. 12, 2015 during the Conference of the Parties to the United Nations Framework Convention on Climate Change (UNFCCC) in Paris. It was opened for signature on April 22, 2016 and went into affect in November 2016. As of May 2017, 195 UNFCCC members have signed the agreement and 147 of them have ratified it. 

_{Source: treaties.un.org}

The Paris Agreement needed "at least 55 Parties to the Convention accounting in total for at least an estimated 55 per cent of the total global greenhouse gas emissions have deposited their instruments of ratification, acceptance, approval or accession."

In other words: 55 countries representing at least 55 percent of the world's total greenhouse gas emissions need to be onboard and executing their reduction plans for this to work. 

View a list of all the members and when they ratified here.

_{Source: treaties.un.org}

The goal

The Paris Agreement's primary goal is to reduce emissions on a global scale with a long-term goal of "keeping the increase in global average temperature to well below 2 degrees C above pre-industrial levels," as the European Commission explains.

Each member country must submit its own plan to reducing its own greenhouse gas emissions. 

World greenhouse gas leaders

The United States had a 17 percent share of the total global carbon dioxide emissions in 2011, according to the Union of Concerned Scientists (UCS). The United States is second only to China when it comes to total carbon dioxide emissions.

The UCS ranked the leading emissions countries in 2011: 

If the US leaves the agreement

At the time of the Paris Agreement, the United States committed to reducing climate emissions by 26-28 percent in a decade. According to Climate Interactive, a non profit in Washington, if the U.S. does not uphold its Paris pledge it would mean an additional world warming of 0.3 degrees (about 1/2 degree Fahrenheit). Here's how Climate Interactive breaks it down:

The difference between the US pledge and the US following the business-as-usual scenario (an unlikely outcome, but illustrative of the US role in climate action) is that US emissions are estimated to be 6.7 Gigatons of CO2 equivalents per year by 2025, compared to emissions of 5.3 GtCO2e/year if the US follows through on its commitments. Global annual emissions would be 57.3 gigatons per year instead of 55.8 gigatons per year, a difference of nearly 3%. US emissions in 2016 were 6.5 GtCO2e/year. If US emissions follow the business-as-usual scenario instead of meeting its Paris pledge, while all other countries fulfill their commitments (and no further action is taken), the world would warm an additional 0.3°C (about one-half a degree Fahrenheit) by 2100.

Read more: What would Paris climate deal look like without US?

ClickOnDetroit Meteorologist Paul Gross held a webcast this past December in which he discussed the science of climate change -- watch here: