A primary goal of ecosystem and Earth System Models is to project the impact of future global change scenarios. Those projections are often dependent on model assumptions about how ecosystems respond to novel climates. Experimental manipulations provide an opportunity to test those model assumptions and provide new information to improve model skill. This is true for terrestrial ecosystems worldwide, but especially relevant to Arctic ecosystems where air temperatures are projected to warm by 5-11°C over the next hundred years. Understanding how plant structural and functional traits respond to projected temperature change is a critical uncertainty in Arctic systems but evaluating model assumptions is challenging in a system where access to reliable line power and operational constraints rule out many approaches. Passive warming has a long history in the Arctic but this approach is only able to elevate air temperature by 1-2°C. At Brookhaven National Laboratory Keith Lewin developed a novel approach to elevate and modulate the temperature inside field enclosures and achieve markedly higher passive elevation and control of temperature. Zero power warming (ZPW) uses solar energy to warm the enclosure and heat exchangers inside and outside the chamber to modulate temperature and prevent overheating. Our Long Island prototype performed well and we were keen to evaluate the approach in Barrow. As part of our 2015 NGEE Arctic field season we are testing this design on the BEO.

Early in July Keith Lewin, Andrew McMahon and Alistair Rogers worked to install a ZPW chamber and a vented control chamber, near the sled shed on Cake Eater Road. Keith assembled the chambers at Brookhaven then packed them up and shipped them to Barrow where we rebuilt them. After laying trail mat to our test site we brought out the ZPW and control chambers, installed the heat exchangers and instrumentation package. The first day of data looks very promising and we have been collecting performance data continuously since the installation and will evaluate the success of the approach this fall.