Ever since President Donald Trump was voted into office, global confidence in U.S. leadership has plummeted. That's according to this year's Global Peace Index.

The 2019 Global Peace Index, which was published on Wednesday, showed that while global approval of leadership in Germany, China and Russia has been steadily on the rise since 2016, approval of U.S. leadership has seen a dramatic decline. 

In 2016, confidence in U.S. leadership was at 45 percent, but fell below 35 percent by 2017. Since then, Steve Killelea (founder of the Institute for Economics and Peace, which produces the Global Peace Index) said, approval has started to plateau, seeing a subtle uptick. However, confidence levels in U.S. leadership still sit below approval of leadership in both China and Germany. 

Overall, Killelea pointed out, levels of support for U.S. leadership have fallen 17 percentage points since 2009. That was when Barack Obama entered the Oval Office, sending approval ratings soaring to 50 percent.

Whereas Obama was "very popular internationally and had historically high levels," Killelea told Newsweek, "the election of President Trump saw a lot of negative press." 

The Global Peace Index founder said he believed that negative press in the international media played a significant role in seeing approval in U.S. leadership drop. 

On average, the 2019 Global Peace Index shows that the level of global peacefulness improved "very slightly" last year, according to the report, representing the first increase in the last five years. 

"Despite this improvement," however, the report said, "the world remains considerably less peaceful now than a decade ago, with the average level of peacefulness deteriorating by 3.78 percent since 2008." 

In addition to heightened political tensions in both the U.S. and Europe, the report said that the global fall in peacefulness over the past decade could be attributed to a wide range of factors. These include "increased terrorist activity, the intensification of conflicts in the Middle East, rising regional tensions in Eastern Europe and northeast Asia and increasing numbers of refugees. 

Killelea said the index also shows the growing threat that climate change poses to global peace. The report shows how many of the "least peaceful" countries in the world also have high risk of climate hazard. These include Somalia, the sixth least peaceful country, which has the highest risk of drought of all recorded countries. 

"These are countries that are at high risk of a degradation of peace because of climate change," Killelea said. "So I do think that climate change is a risk to peace and it's only going to increase over the next 20 years or so."

"As we move forward, that's something that we do need to pay attention to," he said.