A group of students from Adelphi Elementary School learn about climate change during a lesson at Hard Bargain Farm in Accokeek. (Linda Davidson/The Washington Post)

While taking a nature hike, a  group of elementary school students visiting Hard Bargain Farm in Accokeek learned about the impact of humans on the Earth’s environment. The students stopped on a boardwalk at the edge of the Potomac River, where their instructor Maya Higgins, a naturalist for the Alice Ferguson Foundation, a nonprofit which runs the Hard Bargain Farm, asked for their thoughts on extreme changes in the weather.

The students, all 5th graders from Adelphi Elementary School, listened intently as Higgins explained about global warming: “That means the Earth is heating up. … We don’t totally understand what is happening but we do know that people are contributing to the crazy weather. Everything is changing very rapidly. I know you guys are young, but you can make some decisions to change some things.”

Here are a few recent reports that show the urgency of the instructor’s lesson:

NASA recently released a report on the Earth’s vital signs. It found that “Arctic summer sea ice reached its lowest extent on record in 2012”; Carbon dioxide “concentrations are at their highest levels in 650,000 years”; the global average “sea level has risen 4 to 8 inches in the past 100 years”; global “temperatures have increased” and the decade between January 2000 and December 2009 was the warmest on record; and the “Greenland ice loss has doubled between 1996 and 2000.”

NASA reported that “scientists agree it is very likely that most of the global average warming since the mid-20th century is due to the human-induced increases in greenhouse gases, rather than to natural causes.”

A recent report released by the Intergovernmental Panel on Climate Change, an international organization created in 1988 by the United Nations Environment Programme and the World Meteorological Organization to study climate change, found that increased global temperatures in the last 50 years — from 1951 to 2010 — were “very likely” caused by human activity contributing to an “increase in greenhouse gas concentrations.”

The report released in September found changes in different climate systems, “including warming of the atmosphere and ocean, sea level rise, ocean acidification, and changes in the water cycle, the cryosphere and climate extremes points to a large-scale warming resulting primarily from anthropogenic increases in greenhouse gas concentrations.”

Each decade since 1850 has been warmer than the preceding decade, the report found. “In the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1,400 years,” the report stated. “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased… Human influence on the climate system is clear.”

The report also found that ice sheets in Greenland and in the Antarctic are melting and glaciers are shrinking, and that the Arctic sea ice continues to shrink, an occurrence that I wrote about in a series of stories while working in the Canadian Arctic.

Back on the farm, the Alice Ferguson Foundation is on an urgent mission to save the environment. The foundation is building a “Potomac Watershed Study Center,” designed to meet the “Living Building Challenge,” a conservation code requiring a building to produce “zero-net water, zero-net energy and to be carbon neutral.” The $15.7 million “Living” building, which was funded by the county, state and private donations, will be built to have “no negative impact on the surrounding environment.”

The new buildings will “embrace the most energy-efficient, stringent set of green building requirements on the planet today called the ‘Living Building Challenge,’” Lori Arguelles, the foundation’s executive director, said during an interview. “The requirements of this building are net-zero energy, which means we don’t use any more than we gather, net-zero water, based on the same principle — we don’t use any more than we gather.”

The building is carbon neutral, non-toxic. “There are currently only four ‘Living-Building’ certified buildings in the world today. So here at the Southern tip of Prince George’s County will be one of the next buildings to come on line,” Arguelles said.