Uncertain climate models impair long-term climate strategies

Terra Daily: A new paper published in Philosophical Transactions of the Royal Society A, explains weaknesses in our understanding of climate change and how we can fix them. These issues mean predictions vary wildly about how quickly temperatures will rise. This has serious implications for long term political and economic planning. The papers lead author is Dr Nigel Fox of The National Physical Laboratory, The UK's National Measurement Institution.

The Earth's climate is undoubtedly changing, but how fast and what the implications will be are unclear. Our most reliable models rely on data acquired through a range of complex measurements. Most of the important measurements - such as ice cover, cloud cover, sea levels and temperature, chlorophyll (oceans and land) and the radiation balance (incoming to outgoing energy) - must be taken from space, and for constraining and testing the forecast models, made over long timescales. This presents two major problems.

Firstly, we have to detect small changes in the levels of radiation or reflection from a background fluctuating as a result of natural variability. This requires measurements to be made on decadal timescales - beyond the life of any one mission, and thus demands not only high accuracy but also high confidence that measurements will be made in a consistent manner.

Secondly, although the space industry adheres to high levels of quality assurance during manufacture, satellites, particularly optical usually lose their calibration during the launch, and this drifts further over time. Similar ground based instruments would be regularly calibrated traceable to a primary standard to ensure confidence in the measurements. This is much harder in space.

The result is varying model forecasts. Estimates of global temperature increases by 2100, range from ~2-10 [degrees]C.

From NASA: Satellite data and images such as those presented in this image of Earth give scientists a more comprehensive view of the Earth's interrelated systems and climate. Four different satellites contributed to the making of this image. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) provided the land image layer and is a true color composite of land vegetation for cloud-free conditions from September 18 to October 3, 1997. Each red dot over South America and Africa represents a fire detected by the Advanced Very High Resolution Radiometer. The oceanic aerosol layer is based on National Oceanic and Atmospheric Administration (NOAA) data and is caused by biomass burning and windblown dust over Africa. The cloud layer is a composite of infrared images from four geostationary weather satellites?NOAA's GOES 8 and 9, the European Space Agency's METEOSAT, and Japan's GMS 5.