People all over the world and in Boston shared their appreciation for the planet Monday while marking Earth Day 2019.
From politicians to astronauts to celebrities, it's the time of year when people urge one another to take better care of the earth.
Forty years ago, Boston Harbor was one of the dirtiest waterways in the country because of decades of raw sewage seepage. But now, it's one of the cleanest but there are new pollutants to worry about.
In-depth news coverage of the Greater Boston Area.
"The harbor was a big sewer pipe and the city itself was built with its back to the water because it smelled, it was ugly, it was awful," said Massachusetts Water Resources Authority Executive Director Fred Laskey.
It took more than three decades and an investment of $4 billion in waste water treatment technology to turn the waterway into a whole new harbor.
"Surveys that were done showed that the harbor floor was dead, now its alive, its vibrant," Laskey said.
Although it was arguably one of the largest environmental success stories in history, there are new concerns.
Woods Hole Oceanographic Institution Senior Scientist Chris Reddy says there are concerns with erosion, ocean acidification, excessive land use and run off. The biggest concern may be carbon dioxide. Plastic surprisingly wasn't on his list. Reddy says we don't know enough about plastic to consider it a major problem.
"We added something to gasoline; something called MTBE, about 15 years ago, it made gas really stinky," said Reddy. "We thought that it was going to do a good job, and ultimately it contaminated a lot of our ground water."
Research has uncovered that in communities with bans on plastic bags, there has been a surge in the same of plastic trash bags with increases of up to 125 percent.
Nearly 22 percent of plastic bags were reused as trash bags.
The bags are made out of different kinds of plastics. Trash bags are made from thicker, heavier plastic. Heavier plastic release more green house gasses.
Reddy thinks carbon dioxide emissions are one of the biggest problems we face.
"If carbon dioxide was black, no one would be thinking about plastic," said Reddy. "If we saw that our air and what we saw everyday was getting blacker and blacker because CO2 was in the atmosphere, I think people would take climate change and increased amounts of CO2 in the atmosphere more seriously."