The election of a president who has called global warming a "hoax" has understandably worried green campaigners, or indeed anyone who has a vested interest in the environment.
The US election comes as the World Meteorological Organisation (WMO) warned the planet had just experienced its hottest five-year period on record and is expected to confirm 2016 as a new record hot year in the coming days. As such, the environment has never been higher on the political agenda.
However, Donald Trump doesn't seem to share this view. He has said global warming was created by the Chinese to make US manufacturing unprofitable, and has pledged to pull out of the Paris Agreement. This could have a huge impact on the world's battle against climate change.
The Paris Agreement is the world's first comprehensive treaty on climate change which came into force last week. The US ratified the deal earlier this year alongside China and no country can easily pull out for at least three years now that it has come into force.
In contrast to Barack Obama, who made climate change a key policy area, Trump has called global warming a "hoax" on social media and pledged in May to "cancel" the Paris deal, which was adopted in the French capital last year.
More than 100 countries, including the US, have formally joined the agreement, which seeks to reduce emissions of climate-warming greenhouse gases and help vulnerable countries adapt to rising seas, intensifying heatwaves, the spreading of deserts and other climate changes.
The withdrawal process would take four years - an entire presidential term - under the agreement, but Trump could decide to ignore the Obama administration's Paris pledge to reduce US emissions by 26%-28% from 2005 levels by 2025. The pledges are self-determined, and there is no punishment for countries who miss their targets.
As you can imagine, environmental experts and activists are pretty glum at the outcome of the election.
Kelly Stone, ActionAid policy analyst, said climate change was already having a major impact on the lives of millions of people in the US and around the world.
"The US has joined the Paris Agreement and must continue to meet its climate obligations. Leaving this important international agreement will damage our credibility with important overseas partners and would be a major setback in the fight against climate change."
"It seems like a most miserable US election result for climate stewardship prospects," said Jason Box, a glacier expert at the Geological Survey of Denmark and Greenland. "Can the world do climate stewardship without the US? It has to."
However, maybe the world can survive if Trump does make good on his threats. Mohamed Adow, Christian Aid's international climate lead, said: "Last year's Paris Agreement showed the world was united in its concern about climate change and its commitment to decarbonising the global economy. The rest of the world will not risk a global climate catastrophe because of one man's opposition."
While Trump's exact plans for his environmental policies remain a bit vague, in the past he has hinted he wants to do away with the Environmental Protection Agency, all federal spending on clean energy and scrap Obama's regulations to reduce carbon dioxide emissions.
If any of these things do indeed come to light, the impact on the environment will be huge.