PROVO — Until now, humans have had room for error in regard to emitting carbon dioxide into the atmosphere.

But now, Brigham Young University Biology professor and climate change expert Richard Gill told a group of students and professors Thursday at BYU, the earth has essentially reached its potential to absorb and store carbon dioxide. The result, he said, is that climate change is more of a reality now than ever before.

"Since the Industrial Revolution, a lot of what we've done has been softened because of the natural system's ability to slow down warming by absorbing (carbon dioxide)," he said. "Native systems have buffered our impact on the earth's climate system, but that buffering capacity is limited and at least as far as ability of soils to sequester carbon, we've reached that point."

Recently, Gill was involved in a study in Texas where he and others observed grassland growth under a variety of different atmospheric conditions. He said the study showed the grassland system, which absorbs carbon at a rate better than other systems, reaches a point where it can absorb no more. Current levels of carbon dioxide are reaching that capacity. The result is human-caused carbon dioxide entering the atmosphere at an unprecedented rate.

Using data gathered from 800,000 years of Antarctic ice, Gill said, scientists can look at the chemical makeup of the atmosphere over time. He said the amount of carbon dioxide in the atmosphere remained relatively constant for the past 1,000 years until it started to rise in about 1750. In the past 40 years, however, the percentage of carbon dioxide in the atmosphere has risen as much as it rose between 1750 and 1969, and it continues to increase all the time.

The consequences of climate change in Utah specifically, Gill said, will be quite significant. And as an ecologist who maintains climate change is happening, Gill said he is interested in what those consequences are.

"If Utah is three degrees Celsius warmer 100 years from now, what's that going to do to the forests on the Wasatch Front?" he said. "Or what's that going to do to soils, or how is that going to impact water coming off the Wasatch Plateau?"

He said such an increase in temperature could mean 30-40 percent less water for irrigation, a 50-70 percent smaller snow pack and an average climate similar to the droughts of the 1930s. Gill said his interest isn't in debating whether the climate is changing, but what the reasons are behind it and what the result is.

"I think that the political debate really is about how we deal with it," he said. "The scientific community really has come to a point where, with the exception of a few very vocal skeptics, we actually do recognize that change in greenhouse gas composition changes climate. Climate has changed — it's going to have far-reaching impacts."

Gill used examples from findings published in 2007 by the International Panel on Climate Change and studies he took part in to show the reasons behind climate change, which he said is often misrepresented in politics. He said the validity of climate change is nearly universally accepted by the scientific community and is not controversial.

"The really interesting policy changes that are occurring with regard to climate change are actually coming from local- and state-level elected officials," Gill said. "The federal government is moving at a glacial pace ... If you look to places like Seattle or Chicago or Atlanta, there are progressive mayors, progressive governors, who are coming together and affecting climate change in a way that is leaving the federal government behind."

BYU chemistry professor David Belnap said he invited Gill to speak after he realized how much he didn't know about climate change when the topic came up in his classes. He said those discussions angered some of his students, who thought he was crossing the political neutrality line by bringing up a hoax.

"A lot of them are worried that their freedom is threatened," he said. "I think our freedom is more threatened if we allow it to go on and don't do something about it."