President Joe Biden was marking Earth Day on Friday by ordering protections for the United States' ancient forests, seen as a crucial weapon in the fight against climate change, during a trip to Seattle.

The Democrat has campaigned heavily for environmental protections and US leadership in the response to global warming, but has regularly run up against lack of support in Congress.

His executive order, signed in the heavily wooded and often spectacularly wild Washington state, will recognize the importance of America's old-growth forests in regulating climate change -- but also their vulnerability in an era of ever more intense wildfires.

In the order, Biden requires officials overseeing federal lands to inventory mature forests within a year and to identify threats to the trees.

"America's forests are a key climate solution, absorbing carbon dioxide equivalent to more than 10 percent of US annual greenhouse gas emissions," the White House said in a statement.

"Federal lands are home to many of the nation's mature and old-growth forests, which serve as critical carbon sinks, cherished landscapes, and unique habitats.

US President Joe Biden is in Seattle to announce an order protecting US old-growth forests
US President Joe Biden is in Seattle to announce an order protecting US old-growth forests AFP / MANDEL NGAN

"However, these magnificent ecosystems are threatened by the climate impacts that are already here, with intensifying wildfires demanding urgent action to protect our forests and the economies that depend on them."

Throughout his presidency, Biden has set ambitious environmental goals and he quickly reversed his Republican predecessor Donald Trump's move to pull the United States from the Paris climate accords.

However, with a barely functional majority in Congress, he has seen major policy initiatives on the environment fail to get off the ground.

Many of Biden's biggest pushes have come through executive orders, which do not require congressional approval, but can be countermanded by the next president.

On Tuesday, the Biden administration said it was restoring safeguards weakened by Trump, including a requirement for assessing climate impacts from infrastructure projects.

This will play a key role in the wave of public works set to unroll across the country under the White House's successfully passed $1 trillion infrastructure spending bill.