Carbon and greenhouse gas budgets of Europe: trends, interannual and
spatial variability, and their drivers
Abstract
In the framework of the RECCAP2 initiative, we present the greenhouse
gas (GHG) and carbon (C) budget of Europe. For the decade of the 2010s,
we present a bottom-up (BU) estimate of GHG net-emissions of 3.9 Pg
CO2-eq. yr-1 (global warming potential on 100 year horizon), and are
largely dominated by fossil fuel emissions. In this decade, terrestrial
ecosystems are a net GHG sink of 0.9 Pg CO2-eq. yr-1, dominated by a CO2
sink. For CH4 and N2O, we find good agreement between BU and top-down
(TD) estimates from atmospheric inversions. However, our BU land CO2
sink is significantly higher than TD estimates. We further show that
decadal averages of GHG net-emissions have declined by 1.2 Pg CO2-eq.
yr-1 since the 1990s, mainly due to a reduction in fossil fuel
emissions. In addition, based on both data driven BU and TD estimates,
we also find that the land CO2 sink has weakened over the past two
decades. In particular, we identified a decreasing sink strength over
Scandinavia, which can be attributed to an intensification of forest
management. These are partly offset by increasing CO2 sinks in parts of
Eastern Europe and Northern Spain, attributed in part to land use
change. Extensive regions of high CH4 and N2O emissions are mainly
attributed to agricultural activities and are found in Belgium, the
Netherlands and the southern UK. We further analyzed interannual
variability in the GHG budgets. The drought year of 2003 shows the
highest net-emissions of CO2 and of all GHGs combined.