A potential 4-foot rise in sea levels and worsening droughts have made coastal flooding and prolonged dry spells two of the top dangers of climate change, members of the White House science team say.

The Obama administration published the country’s third National Climate Assessment on Tuesday morning, an in-depth review of how global warming has been affecting eight regions across the nation.

The assessment, compiled by hundreds of scientists and experts, amounts to “the loudest and clearest alarm bell to date signaling the need to take urgent action to protect Americans from the effects of climate change,” White House Science Adviser John Holdren said in a call with reporters.

Flooding and droughts – in addition to longer allergy seasons, stronger storms, and other issues – were chief among the team’s concerns.

Seas may rise by anywhere from 1 to 4 feet – an upper limit more than twice as high as the estimate put forward in the last assessment in 2000 – and droughts have been lasting longer than ever. Meanwhile, typically moist areas are getting moister and dry areas even dryer.

“Climate change is not a distant threat, it is already affecting every region of the country and key sectors of the economy,” Holdren said. “What we are observing is consistent with the ongoing changes in global climate.”

Floods and dry spells pose particular threats: Miami and New York City, as well as Norfolk, Virginia, and Portsmouth, New Hampshire, are all low-lying cities that have already felt the effects of rising sea levels, from high tides that regularly flood sewer drains in Miami, to the devastation of Hurricane Sandy in October 2012 – the kind of severe storm that not only may become much more frequent as global temperatures increase, but also cause wider flooding and larger storm surges as the seas rise.

“These places are experiencing the impacts of sea-level rise already in very serious and expensive ways,” said Jerry Melillo, distinguished scientist at the Marine Biological Laboratory and chairman of the assessment’s Development Advisory Committee.

Droughts in the southwest, meanwhile, have led to far longer wildfire seasons and disastrous harvests for farmers.

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Temperatures in the United States have risen by about 1.5 degrees Fahrenheit since 1895, and the last decade marked the country’s hottest on record. New satellite data has also shown that ice sheets in Greenland and Antarctica are rapidly melting, pouring enough water into the oceans to fill Lake Erie and Lake Ontario.

“Ice sheet melting over the coming decades will determine the rate of sea level rise in that upper limit during this century,” Melillo said, calling the issue “a sleeping giant in the sea level equation.”

The report was released about a month after a United Nations panel released its own two reports on the effects of global warming and how they might be mitigated.

It also comes amid furious debate regarding the controversial Keystone XL pipeline from Canada to the U.S., which has become a key flashpoint between environmentalists and industry groups, and one month before the Obama administration takes another step in the Climate Action Plan the president unveiled last summer: new emissions regulations for power plants.

Following the report’s release, energy groups accused the Obama administration of “climate change scare tactics.”

“Facing a recovering, yet fragile economy, with families across the country struggling to make ends meet, it is concerning that the Obama administration is busy promoting its politically driven climate change agenda, instead of addressing the real issues plaguing our nation,” Laura Sheehan, senior vice president for communications of the American Coalition for Clean Coal Electricity, said in a statement.

Nevertheless, the White House team said it hoped the report – and the urgency it voiced – would spur lawmakers at all levels to action.