As the entrusted entity for implementing the Copernicus Atmosphere Monitoring Service (CAMS), ECMWF will issue an Invitation to Tender (ITT) to provide quantitative estimates of climate forcings
Uncertainties also remain in historical climate forcings
by various agents, including anthropogenic aerosols.
IPCC modelers assume Global Climate Models (GCMs) are based on a perfect knowledge of all climate forcings
The researchers built a climate model that incorporated all of the known factors that contribute to human-induced climate forcings
since 1750, as well as fluctuations in climate caused by natural factors such as volcanic eruptions and solar activity, and measurements of air, ground and ocean temperatures.
For their analysis, Professor Berntsen and his colleagues entered all the factors contributing to human-induced climate forcings
since 1750 into their model.
Changes in other future climate forcings
also remain unknown.
Finally, all climate forcings
(aerosols, methane and CO2 concentrations, etc) are set to observed values for the period 1960-2000 and follow the scenario A1B afterwards.
2] Human activities like deforestation and burning fossil fuels are anthropogenic climate forcings
A great advantage of framing the problem of climate change detection as a multiple regression is that we can examine the residuals of regression--the variations in the observations that are "left over" after we have extracted the estimated responses to known climate forcings
--to assess whether there is evidence for any "missing forcing.
The three scenarios (see figure, opposite page) were intended to bracket the range of likely future climate forcings
(changes imposed on the Earth's energy balance that tend to alter global temperature either way).
This inconsistency between the observations and the CMIP5 All-Forcing ensemble could be due to a number of factors including: 1) mis-specified or missing climate forcing
agents in the models; 2) errors in the model responses to the climate forcings
; 3) underestimation of Arctic internal climate variability in the models; or 4) data issues, including problems with comparing modeled and observed Arctic data as discussed above.
The observed trends will be analyzed at seasonal and regional scales in order to disentangle natural (weather/dynamical) variability and human-induced climate forcings