The main heat-trapping gases that humans emit into Earth’s atmosphere – carbon dioxide, methane and nitrous oxide – are increasing faster than ever and have reached record levels.

Atmospheric concentrations of the CO2 increased more between 2015, 2016 and 2017 than ever before during 58 years of measurements, according to the National Oceanic and Atmospheric Administration. The global average carbon dioxide concentration of 405 parts per million now is higher than at any time in 800,000 years, NOAA officials said this week.

And while methane lasts less than 10 years in the atmosphere before breaking down, methane’s heat-trapping effect over a decade is 86 times stronger than CO2. Global average methane levels increased from 1,837 parts per billion in June 2016 to 1,843 ppb in June this year, NOAA records show.

On Wednesday, Boulder-based NOAA atmospheric chemist Thomas Ryerson and colleagues responded to Denver Post questions.

Q: What do these record-high levels mean for the climate change effects we may feel?

A: Increasing concentrations of greenhouse gases will increase the amount of heat trapped in Earth’s atmosphere and oceans with a wide variety of known and unknown effects on weather, crops, wildlife and people.

Q: Why are these concentrations of greenhouse pollutants increasing faster?

A: Scientists don’t fully understand why CO2 has increased at record rates the past two years. Several NOAA studies have pointed to tropical wetlands a source for rising methane emissions since 2007.

Q: What questions are raised by the acceleration of emissions?

A: Rising rates of CO2 and methane emissions raise the question of whether this is a result of increased emissions from human activities, or if warming has triggered a positive feedback loop. In other words, have warming temperatures from greenhouse gas emissions led to more greenhouse gas emissions from wetlands, arctic permafrost thaw, etc.?

Q: Nations have been trying to reduce greenhouse gas emissions, including CO2 and methane. Why are the concentrations still increasing?

A: Humans emit about 10 gigatons of carbon into the atmosphere each year. CO2 has a lifetime of up to a thousand years in the atmosphere. Even if the rate of annual CO2 emissions stabilizes, the amount of CO2 stored in the atmosphere will continue to increase.

The cause of rising atmospheric methane concentrations is a source of robust scientific research. Methane has a variety of sources: agriculture, wetlands, oil and gas, etc. More research is needed to understand where increasing levels of methane are coming from.

Q: If governments target sources of short-life pollutants, including methane, ozone and soot, how fast could humans see reduced concentrations in the greenhouse-gas blanket around Earth?

A: Methane has a lifetime around 10 years. Ozone and soot are much shorter. Conceivably, we could reduce the rate of warming on a timescale of several years. But levels of CO2, which lasts for up to a thousand years, will ultimately determine the extent of the warming.

Q: Once scientists complete this airborne measuring project exploring concentrations of heat-trapping pollutants all around the planet, how easy will it be to pinpoint the sources of the pollutants?

A: We use the chemical fingerprint of each sample, along with high-resolution weather models, to deduce source regions with fairly high accuracy.

Q: Will NOAA continue this systematic airborne measuring approach — infusing data into climate change predictions — after this four-scan project is completed next year?

A: We are partners in a NASA-funded mission. There are no plans to continue this work past mission completion.