CO2Sigma Space Corporation partnered with Picarro Corporation, Penn State University and CLIMMOD scientists in the City Carbon project, demonstrating near real-time carbon emission estimates in the city of Davos, Switzerland, before, during, and after the World Economic Forum (WEF) Annual Meeting (2012).

City Carbon combines measurements from the high-precision and easy-to-use Sigma Space MiniMPL (Mini Micro Pulse LiDAR) and Picarro gas analyzers with carbon-cycle modeling and analysis in order to demonstrate how urban greenhouse gas (GHG) emissions can be monitored in near real-time. Such networks can provide up-to-date feedback on the GHG emissions from socioeconomic activity and pollution reduction efforts. Cities emit more than 70% of the world’s GHGs, and present the largest opportunity for lowering carbon emissions. Advances in science and technology now allow us to quantify carbon emissions in near real time using data from high-precision instruments that continuously measure a city’s air.

The MiniMPL measures the height of the Planetary Boundary Layer (PBL). The PBL is the layer of air closest to the earth, which collects the CO2 and other GHG emissions from surface sources of emissions. The height of the PBL changes depending on many factors including pressure, temperature, terrain and moisture levels. The PBL depth is directly correlated with emission estimates.

The MiniMPL measurements during City Carbon showed a surprisingly low PBL height in the alpine winter skies above Davos. These were very challenging atmospheric conditions for such PBL measurements, and helped the project avoid errors and improve confidence in the City Carbon emission estimates.

City Carbon analyses showed that prior to the WEF CO2 emissions were 35 percent higher than the annual average rate of emissions inferred from accounting-based GHG inventories (adding up sources).

Surprisingly, City Carbon emission estimates during the meeting were 40 percent below the pre-WEF emission estimates. Following WEF, emissions have increased again to 40% above  accounting-based inventories during an extremely cold period.

 “If the nations of the world are going to get serious about limiting climate change, we need to put the right price on the carbon going into the air,” said Phil DeCola, Chief Science Officer of Sigma Space. “Emissions data will need to be reliable to have a healthy carbon market,” he concluded.

“The atmosphere doesn’t lie. Efforts to reduce greenhouse gas emissions require validation. The Atmosphere captures all emissions, and atmospheric measurements provide a unique and powerful mean of continuous validation,” said Professor Ken Davis of Penn State University. 

To learn more about City Carbon visit


The figure shows two vertical profiles of backscattered light measured in 30 seconds by the MiniMPL. The green and red lines show the received backscatter signal versus height in km. The green line shows signal with same polarization as the transmitted laser and the red line shows the cross polarized signal. The two differently polarized signals give information about particle shape and can distinguish liquid water clouds from ice clouds. These two profiles show the presence of a thin liquid water cloud just above 1 km and a thicker layer of ice clouds from 7 - 10 km. The orange triangle indicates a PBL height of 330 meters determined by wavelet analysis of the LiDAR signal.
Davos, Switzerland, February 2012.