Mendocino Complex Fire on August 4, 2018. Credit: Glenn Morrill, Bureau of Land Management

In California, more than 14,000 firefighters are trying to contain large wildfires that have already destroyed more than 470,000 acres and 11,000 homes. Seven people have died in the Carr Fire, which is still growing. The Mendocino Complex fire, which exploded over the weekend, is now the second-largest in California history. The Ferguson Fire near Yosemite National Park has claimed two lives and closed the park indefinitely.

President Donald Trump approved a “major disaster” declaration yesterday and ordered federal assistance for state, tribal, and local efforts to fight fires in California’s Shasta County. Today, though, the president issued a tweet that demonstrated shocking ignorance about California’s fires.

California wildfires are being magnified & made so much worse by the bad environmental laws which aren’t allowing massive amounts of readily available water to be properly utilized. It is being diverted into the Pacific Ocean. Must also tree clear to stop fire from spreading! — Donald J. Trump (@realDonaldTrump) August 6, 2018

In his tweet, Trump claimed that environmental laws are magnifying California wildfires by “diverting” water to the Pacific Ocean. In reality, there are zero reports of water shortages for any of California’s ongoing firefighting efforts, and there are zero places in California where water is diverted to the ocean. It’s possible that Trump was referring to laws that prevent industries, power plants, farms, and cities from sucking up every last drop of Western rivers before they reach the ocean—but those laws safeguard firefighting water supplies as well as fish.

It’s unclear whether Trump’s call for tree clearing “to stop fire from spreading” referred to creating fire lines by felling trees (a common and effective firefighting strategy) or to the mistaken notion that cutting down the nation’s forests is a good way to restore them to a healthier, more fire-resistant condition. While forest thinning and prescribed burns can help reduce fire risk, they are labor-intensive and must be done regularly. And in the case of the most recent California fires—which have burned populated areas as well as forests—hot, dry, windy weather is playing a bigger role than vegetative fuel loading.

Climate change, which is associated with an increase in extreme weather, is just one reason why wildfires are getting worse every year. Despite decades of warnings about the dangers of building new homes in fire-prone areas, more than a third of the houses built in the United States since 2000 have been in these areas.

As the fires rage in California, Trump is proposing to slash federal funding for wildfire science and to eliminate the Joint Fire Science Program run by the Forest Service and six Interior Department agencies. Past research has led to better methods and tools for predicting fires and responding to them, and for reducing the risks to people and property. At a time when fires are becoming increasingly expensive, and climate change is making the problem worse, wildfire science is needed more than ever. The Trump administration has offered no reason for its proposed cuts.