Israel haters like to pretend that this is their holiday, and associate it with environmentalism, or climate change, or whatever else they can pretend to associate with it. One "Jewish Voice for Peace" event says "The event will include a group reading from Jews, Palestinians, and other activists as we acknowledge and mourn the ongoing suffering endured by Palestinians from the founding and expansion of Israel." and pay special attention to the million olive trees allegedly destroyed by Israel when building the separation barrier.
(Little reported is that when Israel uprooted those trees they replant them on the Palestinian side.)
As usual, the haters are trying to hijack something that is not only Jewish, but distinctly Zionist.
The original mention of Tu B'Shvat is in the Mishnah. The date that was designated as the "new year for trees" is meant to calculate the age of trees in the Land of Israel for various halachic reasons as to when the fruit of a tree is allowed to be eaten and for various tithes.
It only applies to the Land of Israel.
Later, the kabbalists instituted a "Tu B'Shvat seder" where they would ascribe symbolic meaning to fruits and trees...
...but only those fruits and trees that grow in the Land of Israel.
It was showing the attachment that Jews have for Eretz Yisrael.
With modern Zionism, Tu B'Shvat became a day to plant trees in Israel. The first such event was done by Rabbi Ze'ev Yavetz, an early religious Zionist, who took his students to plant trees in Zichron Yaakov.
In 1933, a tree was planted in Israel in honor of president-elect Franklin D. Roosevelt, among thousands of others for a project to honor the bicentennial of George Washington's birth. He wrote back that "some day I want to see that tree in person - I have never yet been to Palestine and hope to go."
For 2,000 years, Tu B'Shvat has been linked to love that Jews have for the land of Israel. And nothing can take that away.