Pacific Press via Getty Images Protesters at City Hall in New York on Nov. 28 called on the city to divest public money from banks that fuel climate change. The largest source of greenhouse gas emissions from human activities in the U.S. is burning fossil fuels.

A fresh round of international climate negotiations, called COP24, kicks off in Poland next week. This annual event brings together world leaders, scientists, campaigners, the private sector and local community representatives to debate how to address climate change and put in place policies to tackle it. Here are some of the key things you need to know.

1. Climate Change Is Already Happening

Climate change is not just a future concern; it’s happening now. The 20 warmest years on record have been in the past 22 years, with the top four being the last four years, according to the World Meteorological Organization.

2. Humans Have A Lot To Answer For

Every four years, the U.S. government is required by law to produce a National Climate Assessment. The first volume of the most recent edition, which was issued last year, concluded that “it is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century.”

Despite this, only 29 percent of Americans surveyed said they believe human activity is the main cause of climate change, according to a new Monmouth University poll.

The largest source of greenhouse gas emissions from human activities in the U.S. is burning fossil fuels such as coal and natural gas for transportation, heat and electricity, according to the Environmental Protection Agency.

3. The Effects Are Being Felt Across The U.S.

The second volume of the latest National Climate Assessment, published on Nov. 23, warned that unchecked warming from greenhouse gas emissions would substantially damage the U.S. economy. It also said that the effects of climate change “are already being felt in communities across the country.”

These effects include continued damage to transport, energy supply, water quality and quantity and human health. In each instance, the report said the problems are expected to worsen with additional climate change.

4. Donald Trump Is In Denial

Asked about the findings of his own administration’s latest climate report — which involved 13 federal agencies and was authored by more than 300 researchers — President Donald Trump said on Monday, “I don’t believe it.”

MANDEL NGAN via Getty Images President Donald Trump greets supporters at a political rally in Charleston, West Virginia, on Aug. 21. Despite the conclusions of reports produced under his administration, he denies that human activity has led to climate change.

Many criticized the decision to publish the report the day after Thanksgiving, when most Americans are not paying attention to news. “Publishing a dire climate report in the final hours of Black Friday might be the biggest Friday news dump of them all,” wrote Robinson Meyer, The Atlantic’s climate change reporter.

5. The U.S. Is Making Some Progress...

Despite the ongoing reluctance of the Trump administration to acknowledge the severe threats posed by climate change, the U.S. is making some progress in addressing the issue.

For example, more than 90 cities have adopted 100 percent renewable-energy goals, and an additional six have already hit their targets. In New York City, legislation to dramatically decrease emissions from big buildings has been proposed that, if passed, would set a new standard for cities around the world.

6. ... But Let’s Not Get Carried Away

U.S. fossil fuel production is going strong. Crude oil production in the U.S. grew 5 percent from 2016 to 2017, according to the Energy Information Administration, which projects further growth in 2018 and 2019.

Likewise, the EIA estimates that energy-related carbon emissions declined from 2005 to 2017 but projects that they will rise 1.8 percent from 2017 to 2018, then remain virtually unchanged in 2019.

It’s also worth noting that a Polish coal company was announced as the first sponsor of this month’s U.N. climate talks. Go figure.

7. The Big Picture: There’s A Lot More Work To Be Done

Globally, we need to act fast, given the severity and immediacy of the situation. While some action is being taken around the world to cut carbon emissions, the U.N. said Tuesday that such measures must be tripled to avoid catastrophic warming.

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