Decades of Data Show Spring Advancing Faster Than Experiments Suggest

Plants are leafing out and flowering sooner each year than predicted by results from controlled environmental warming experiments, according to data from a major new archive of historical observations assembled with the help of a NASA researcher.

Researchers use experiments that manipulate the temperature of the environment surrounding small plots of plants to gauge how specific plants will react to higher temperatures. The observed plant responses can then be incorporated into models that predict future ecosystem changes as temperatures around the globe continue to rise. But when a group of scientists compared these results to a massive new archive of historical observations, they found that the warming experiments are dramatically underestimating how plants respond to climate change.

The results were published online in the journal Nature on May 2. In addition to quantifying how a broad collection of plant species have responded to date to rising temperatures, the study suggests that the way warming experiments are conducted needs to be re-evaluated.

NASA Satellite Measurements Imply Texas Wind Farm Impact on Surface Temperature

A Texas region containing four of the world's largest wind farms showed an increase in land surface temperature over nine years that researchers have connected to local meteorological effects of the turbines.The land surface temperature around the west-central Texas wind farms warmed at a rate of .72 degrees Celsius per decade during the study period relative to nearby regions without wind farms, an effect most likely caused by the turbulence in turbine wakes acting like fans to pull down warmer air from higher altitudes at night, said lead author Liming Zhou at the University of Albany, State University of New York.

The results were published in the April 29 issue of Nature Climate Change. Zhou and colleagues studied land surface temperature data ranging from 2003 to 2011, from the MODIS (Moderate-resolution Imaging Spectroradiometer) instruments on NASA's Aqua and Terra satellites.Land surface temperature measures the temperature of the Earth’s surface itself, as opposed to the air temperature readings used in daily weather reports. Across a broad landscape, land surface temperature depends closely on the land cover type and nature of the surface. In specific locations, land surface temperature varies widely from day to night while air temperature varies within a smaller range.

The warming observed by MODIS mostly occurred at night. In the Texas region studied, the land surface temperature after sunset typically cools faster than the air temperature. But as the wind turbines continued to turn, the movement brought warmer air to the surface and thus created a warming effect compared to non-wind farm regions. The researchers expected to see the reverse during the day a slight cooling effect but the data instead showed a small warming or negligible effect in daytime.