The Environmental Protection Agency said Tuesday that it is unmistakably clear that climate change is occurring, adding new tell-tale signs of global warming in its fourth annual report.

"The Earth's climate is changing," the EPA report stated in an executive summary. "Temperatures are rising, snow and rainfall patterns are shifting, and more extreme climate events — like heavy rainstorms and record-high temperatures — are already taking place."

The report adds weather-related events such as heat waves, heat-related illness and "river flooding" as the latest indicators that the climate is going through a profound change that is making these severe weather events more frequent.

Based on the report, Saturday's devastating flash flood in Ellicott City, Md., about 40 miles north of the nation's capital, which killed two people and did millions of dollars of damage in the town's historic district, is an indication of just how much the climate is changing, due to rising amounts of manmade carbon dioxide emissions from the burning of fossil fuels.

"Scientists are highly confident that many of these observed changes can be linked to the levels of carbon dioxide and other greenhouse gases in our atmosphere, which have increased because of human activities," the EPA said.

EPA air chief Janet McCabe, in charge of developing the agency's climate change regulations, said "the signs of climate change are stronger and more compelling" with each new year of data. "This report reiterates that climate change is a present threat and underscores the need to reduce greenhouse gas pollution and prepare for the changes underway, to protect Americans' health and safeguard our children's future."

Last month's massive flooding in West Virginia last month, which killed 23, also would constitute a tell-tale indicator that climate change is occurring, according to the new report.

The report comes a day after the environmental group Natural Resources Defense Council began using the Maryland flood, which grabbed the national spotlight over the weekend, to underscore the need for states to make climate change a central part of their disaster planning and to take steps to make infrastructure more resilient to flooding.

The Ellicott City event occurred after a massive deluge that dropped six inches of rain in two hours, which is the equivalent of an entire month's worth of rainfall.

"According to the National Weather Service, an event like this should statistically happen only once every 1,000 years, based on historical data," said NRDC attorney Beth Hammer in a Monday blog post.

"But because of climate change, extreme events like this one are happening more frequently, and scientists expect that trend to continue into the future," Hammer said. "Our past experiences with floods are no longer a reliable indicator of our present or future risk."

Ellicott City's historic district is prone to flooding, as it is on a hill, along the Patapsco River and a stream that feeds into it.

A week earlier, NRDC submitted comments to Maryland on its latest flood mitigation plan, which the influential environmental group said is woefully lacking when it comes to the changing climate.

"We had expected that Maryland would develop a strong plan that fully integrated climate change considerations. Unfortunately, the current draft of the plan doesn't get the job done," she said.

Hammer added that the Maryland plan has many strengths, but it is also surprisingly lacking in taking steps to calculate future risks from global warming. She said in many ways it takes a step backwards from dealing with climate change.

Underscoring NRDC's point, the EPA added "river flooding" and six other indicators this year to its official list of climate indicators that global warming is occurring. The 2016 report adds seven new indicators: river flooding, coastal flooding, Antarctic sea ice melt, heat-related illnesses, the West Nile Virus, stream temperature, and marine species distribution.

"Nearly all indicators have been updated with additional years of data that have become available since the last report," the report said.