Monitoring of geoengineering climate interventions

The importance of having an accurate monitoring system before commencing geoengineering intervention projects such as solar radiation management (SRM) has been overlooked. If a global change in radiative forcing is made will we wait for 25 years to see if a change in global temperature has occurred? A variable with a fast response is needed to determine the current state of the global warming problem, let alone for modifications. The immediate response of adding greenhouses gases or aerosols to the atmosphere is a change in the climate radiative forcing (radiative forcing). This produces a temperature increase which lags behind the radiative forcing by over 25 years due to the thermal inertia of water bodies. For geoengineering the monitoring problem is more severe; the 25 year lag in temperature would make it difficult to monitor how effective or dangerous a particular strategy would be. The time lag between radiative forcing and temperature response will be graphically demonstrated. The recent “climategate affair” has demonstrated that temperature is not bulletproof as the monitoring variable for the current state of global warming. Extensive debates over the accuracy of the temperature records have taken place. The noise in the temperature record further complicates its use to monitor the effectiveness of geoengineering strategies. Ice melting has been used recently to demonstrate global warming, but still has a 25 year time lag. Similarly, water vapor lags radiative forcing by years since it is controlled by temperature.

Radiative forcing of gases can be measured at the surface with the AERI FTS instrument and at the top of the atmosphere with satellite instruments such as IASI and GOSAT. The short wave spectral flux is also altered by aerosols and ozone depletion is a concern. The use of current and planned satellites to monitor these changes will be described. The OSIRIS and CERES satellite results demonstrate that it would be feasible to setup an effective monitoring system for aerosol radiative forcing. It is proposed to monitor the long wave radiative forcing of global warming by GHG with a new network. The calibrated spectrum of greenhouse radiation at the surface has been measured and the radiative forcing flux from each greenhouse gas extracted. 20 AERI instruments, manufactured by ABB BOMEM, are already deployed around the world.

This network will provide a new experimental dataset to complement the calculated radiative forcings from climate models used for policy determination of safe levels of GHG. This network would support DOE‘s long-term goal to deliver improved scientific data and models on the potential response of climate to increased GHG levels. The analysis of the data from ARM AERI sites, would expedite a network to monitor changes in radiative forcing. Although DOE has archived these valuable records of the ARM AERI spectral data, it needs to process them into radiative forcing, a simple form suitable for use by the world community.

The usefulness of radiative forcing over temperature will be demonstrated by evaluating the present climate on the time line of global warming. Our measurements show a total radiative forcing of 3.3 W/m2 from all GHG. Converting the 2 K Copenhagen target into radiative forcing shows that this is not achievable since only 8 years are left before radiative forcing will exceed the target. Hence, geoengineering should not be attempted without a monitoring system for radiative forcing in place. One might be working in the dark for 25 years without feedback from a fast monitoring system.