Redwoods, part 2: Karl, The fog of San Francisco

Continuing from Part 1 of my article on visiting Muir Woods National Park in San Francisco and witnessing the tallest trees in the world called “the Redwoods,”. Here is the second part that talks about “Karl, the Fog” of San Francisco, why it is critical for the existence of the world's tallest trees in Muir Woods National Park, and how human-created climate change has reduced 33% of the fog, thereby causing existential risks for Redwoods.

Interestingly, when you visit Golden Gate Bridge in San Francisco, you always pray not to have “Karl the fog,” since it spoils your view of the bridge and SF skyline. But if Karl goes, Redwoods would also go.

Its a short read, and I am sure you would love reading it.

Redwood-like trees covered much of the northern hemisphere 150 million years ago. Most redwoods have been cut, but some are protected in redwood national parks and state parks. Two species of redwood remain in the United States, both in California, with very limited ranges. A third species, the dawn redwood, is native only to central China.

Closely related, giant sequoia grows larger in bulk but shorter than redwoods. It is found only in small groves; some of them are protected in Yosemite, Sequoia, and King Canyon national parks.

Coast redwoods are the tallest living things on earth and reach about 379 feet in Redwood National Park. They grow best at moderate temperatures on the coast, as long as they are protected from wind and salt spray. The tallest trees grow along streams like Redwood Creek that periodically flood.

The fog of California:

San Francisco is situated on the Pacific Ocean and is very cold. Sea surface temperatures?along the coast are generally 11–14?°C. The moisture evapourated from the Pacific Ocean surface over hundreds of miles of the open Pacific is carried to California from various directions, creating a layer of vapour called a?marine layer?near the surface of the ocean. And when the marine layer comes into contact with the colder sea water of San Francisco, it cools and condenses. This phenomenon keeps the SF sea very foggy, particularly in the Golden Gate Bridge area, adjacent to Muir Woods National Park. Someone coined the term "Karl,” which is a popular term on social media for this fog.

Role of fog in Redwood survival:

Most of the California region is facing an acute water shortage as I write this article, and it generally gets very little rain. Redwoods flourish only in coastal California, called the fog belt, where frequent summer fog supplies critical moisture to redwoods during the dry summer season. As fog condenses on leaves and needles, the water drips to the forest floor and soaks in, becoming available to the tree roots.

Over the past century, due to human-caused global warming, the fog has reduced by 33%, creating severe risks to the survival of redwoods.

Now you know why sea surface temperature is so critical for nature and how climate changes have cascading effects on many things around us.

In the next and last part of the article, we will talk about the importance of fire in the reproduction of redwoods.

Till then, take care of yourself and your surroundings.