A new report by the United Nations paints a bleak picture for the success of the Paris climate change deal, especially given President Trump's decision to leave the agreement in three years.

The U.N.'s "Emissions Gap" report issued late Tuesday showed that the countries that signed onto the deal are not doing enough to limit greenhouse gas emissions.

"Should the United States follow through with its stated intention to leave the Paris Agreement in 2020, the picture could become even bleaker," a report summary read.

The U.N.'s environment program has been issuing gap reports since 2010 to point out the effect of countries' actions toward the goal of limiting emissions that are raising the temperature of the Earth. Most climate scientists say global warming caused by human activity is raising the Earth's temperature, causing more floods, drought, and ocean acidification.

The eighth edition of the report found that national pledges would reduce emissions by one-third of the required levels needed to meet the climate Paris targets by 2030. It said additional private-sector actions, with state and local emission pledges, are "not increasing at a rate that would help close this worrying gap," according to a summary of the report. A number of states and cities, led by California and Washington state, have pledged to meet the U.S. commitment now that Trump has decided to withdraw from the deal. But based on the gap report's finding, their plans wouldn't be enough.

“One year after the Paris Agreement entered into force, we still find ourselves in a situation where we are not doing nearly enough to save hundreds of millions of people from a miserable future,” said Erik Solheim, the head of the U.N.'s environment agency.

“This is unacceptable," Solheim said. "If we invest in the right technologies, ensuring that the private sector is involved, we can still meet the promise we made to our children to protect their future. But we have to get on the case now.”

The report comes one week before the COP23 U.N. climate change meeting in Bonn, Germany, where countries will examine the steps they need to take to achieve the temperature reduction targets set out by the Paris climate deal.

The Paris agreement seeks to limit global warming by 2 degrees Celsius above pre-industrial levels, with a more ambitious goal of 1.5 degrees. "Meeting these targets would reduce the likelihood of severe climate impacts that could damage human health, livelihoods and economies across the globe," according to the report.

Even with the full implementation of current unconditional and conditional commitments by countries, the Paris accord will make "a temperature increase of at least 3 oC by 2100 very likely — meaning that governments need to deliver much stronger pledges when they are revised in 2020."

That year will be when Trump's exit from the deal will begin under the U.N.'s rules for withdrawing from the agreement. The U.S.' withdrawal timeline also coincides with the 2020 presidential election, which could put someone in place who reverses Trump's decision. If Trump were re-elected to a second term, the exit would go into effect.