Global CO2 emissions have been constantly rising, only flattened somewhat by economic changes.

Judge as of 2010. True: global CO2 emission records (e.g. CDIAC, IEA or Global Carbon Project) show that emissions rose in nearly every year over recent decades up to 2010. Pauses or small dips tied to economic downturns (such as the early 1980s, the early 1990s and 2009) are consistent with the claim's own caveat that economic changes only somewhat flattened the rise. Mostly true: the long-term trend is clearly upward, but there were somewhat more or larger dips than 'constantly' suggests, for example several multi-year declines. Mixed: the rise is real over the long run, but it has been interrupted by flat or falling stretches substantial enough that 'constantly going up' is only half right. Mostly false: emissions were broadly flat or fluctuated over the recent period, with only a weak upward drift. False: global emissions were falling or flat over the relevant decades.

Set before the research began.

1. E1 Rapid growth in CO2 emissions after the 2008–2009 global financial crisis Nature Climate Change (correspondence by Peters, Marland, Le Quéré, Boden, Canadell and Raupach; authors from CICERO, CDIAC and Global Carbon Project) · 4 December 2011

   “Since 1970, global GDP has had one year of negative growth3 (2009), whereas CO2 emissions have had ten disparate years of negative growth.”

2. E2 Global CO2 emissions fall in 2009, but the past decade still sees rapid emissions growth Grist (summarising Earth Policy Institute data) · 21 July 2010

   “bringing global CO2 emissions from fossil fuel use down from a high of 8.5 billion tons of carbon in 2008 to 8.4 billion tons in 2009.”

3. E3 2009 carbon emissions fall smaller than expected BBC News · 21 November 2010

   “What we find is a drop in emissions from fossil fuels in 2009 of 1.3%, which is not dramatic,”

4. E4 PBL rapport 500212001 No growth in total global CO2 emissions in 2009 Netherlands Environmental Assessment Agency (PBL) · June 2010

   “In October 2009, the International Energy Agency (IEA) expected that global CO2 emissions would decrease by 2.6% in 2009 (Reuters, 2009).”

E1, an analysis by Global Carbon Project and CDIAC authors, reports that global CO2 emissions fell in ten separate years after 1970, while global GDP fell in only one of those years (2009). So emissions grew in most years but not in "nearly every" year, and they fell in more years than the single year of negative global GDP growth [E1]. E2 calls 2008 a high, says the past decade still saw rapid emissions growth, and puts the 2009 drop at only about 8.5 to 8.4 billion tons of carbon. E3 also describes the 2009 decline as "not dramatic", and E4's title reports no growth in total global emissions in 2009. Together these sources show a clear long-term rise with more dips than "constantly" suggests, which fits the mostly-true band.