Land overall constituted a net sink of –6.6 (±4.6) GtCO2 yr–1 for the period 
2010–201972 (medium conﬁdence). {WGIII SPM B.2, WGIII SPM B.2.1, 
WGIII SPM B.2.2, WGIII TS 5.6.1} 
Human-caused climate change is a consequence of more than 
a century of net GHG emissions from energy use, land-use and 
land use change, lifestyle and patterns of consumption, and 
production. Emissions reductions in CO2 from fossil fuels and industrial 
processes (CO2-FFI), due to improvements in energy intensity of GDP 
and carbon intensity of energy, have been less than emissions increases 
from rising global activity levels in industry, energy supply, transport, 
agriculture and buildings. The 10% of households with the highest per 
capita emissions contribute 34–45% of global consumption-based 
household GHG emissions, while the middle 40% contribute 40–53%, 
and the bottom 50% contribute 13–15%. An increasing share of 
emissions can be attributed to urban areas (a rise from about 62% 
to 67–72% of the global share between 2015 and 2020). The drivers 
of urban GHG emissions73 are complex and include population size, 
income, state of urbanisation and urban form. (high conﬁdence) 
{WGIII SPM B.2, WGIII SPM B.2.3, WGIII SPM B.3.4, WGIII SPM D.1.1}