Critical Loads and Dynamic Modelling Results
This report describes the results
of the call for critical load and dynamic modelling data that
the Coordination Center for Effects issued on 18
November 2003, with the deadline of 31 March 2004.
Critical loads are thresholds of air polluting compounds which should not be exceeded to protect ecosystems from risk of damage, e.g. from acidification and eutrophication. Dynamic modelling data provide information on the future time required to have an ecosystem recover from such a risk, whenever critical loads are no longer exceeded. For dynamic modelling countries were requested to submit so-called target loads, i.e. a deposition (path) which ensures recovery in a given year and maintained thereafter.
Sixteen countries submitted updated data on critical loads of acidity and of nutrient nitrogen. Eleven countries also submitted the requested target loads.Several countries noted the need for a follow-up call to complete their contributions. The submitted critical load data were compared to depositions computed with preliminary results of the new model of EMEP. The latter model enables the computation of ecosystem specific deposition (e.g. forests), contrary to the old model which computed an average deposition in each 150x150 km2 grid cell. The comparison of ecosystem specific deposition to the 2004 critical loads leads to a larger area of unprotected ecosystems than that computed in the past. It is shown that ecosystems which are unprotected against acidification and eutrophication in 2000 cover 11% and 35% of the European ecosystem area respectively. According to the emissions ceilings prescribed in the Gothenburg Protocol and NEC Directive for 2010, these percentages are computed to be about 8% and 34%, respectively.
J-P Hettelingh, J Slootweg, M Posch
RIVM report 259101014/2004