TREES OF LIFE: A group of international scientists counted all of the trees on earth using satellites and other methods for a study published in Nature. By their estimate, there are a total of 3.04 trillion trees, or about 422 trees per human.

POLLUTION DOESN'T GROW ON TREES: According to a study from the University of Leicester, trees play an important role in dispersing emissions from cars by causing wind turbulence.

CALIFORNIA DREAMING BIG: Several carbon emission bills that passed the California State Senate in June are going to the Assembly for a vote this week. One bill would require the state to reach emission levels 80 percent lower than 1990 by 2050, setting the most ambitious standard in the country. The bills are expected to pass despite resistance from the oil lobby.

NO MORE DENYING DENALI: Before setting off on his trip to Alaska, President Obama announced that the federal government will now refer to Mt. McKinley, the tallest mountain in North America, by its Native Alaskan name, Denali. McKinley’s home state of Ohio has blocked Alaska’s efforts to rename the mountain for decades.

AVIAN PLASTIC PROBLEM: The rate of seabirds found with plastic in their stomachs rose from 5 percent in 1960 to 80 percent in 2010, according to a study published this week. The study’s authors project that 99 percent of birds will be affected by plastic ingestion by 2050.