Carbon dioxide levels were highest on record in 2018.

The last 4 years have been the Earth's 4 warmest years on record.

Extreme weather worsening as globe warms.

Extreme weather events, supercharged by climate change, affected some 62 million people around the world in 2018, the United Nations' weather agency said Thursday.

In its yearly "State of the Climate" report, the World Meteorological Organization (WMO) said the planet's biggest weather woes last year were floods (which swamped some 35 million people), and droughts, which affected another 9 million.

Since 1998, about 4.5 billion around the world have been hurt by extreme weather.

“We have seen a growing amount of disasters because of climate change,” said WMO Secretary-General Petteri Taalas.

Taalas said that in the past 25 years, climate science has improved dramatically. This has provided solid evidence of accelerating sea level rise, shrinking sea ice, increasingly acidic oceans, glacier retreat, shrinking polar ice, and extreme events such as heat waves.

The report said the Earth is almost 2 degrees (Fahrenheit) warmer than it was in the late 1800s, and that the past four years have been the warmest on record.

Climate change, aka global warming, is caused by burning fossil fuels such as coal, oil and gas, which release greenhouse gases like carbon dioxide and methane into the Earth's atmosphere and oceans. This has raised the global temperature and also worsened climate and weather disasters around the world, the U.N. said.

Climate crisis:Coal still king as global carbon emissions soar

Levels of carbon dioxide in the Earth's atmosphere reached record levels in 2018.

U.N. Secretary-General Antonio Guterres said Thursday that "climate change is a security and health issue for the world."

UN's dire warning:Act now on Earth's environment as human health 'increasingly threatened'

The devastation shows no signs of letting up: “Extreme weather has continued in early 2019, most recently with Tropical Cyclone Idai, which caused devastating floods and tragic loss of life in Mozambique, Zimbabwe and Malawi," said Taalas. "It may turn out to be one of the deadliest weather-related disasters to hit the Southern Hemisphere.”

At least 750 people were killed in the storm. with millions more in need of urgent help.

Contributing: The Associated Press