Hi John, I think you may be forgetting that about half the CO2 emitted is immediately absorbed by land and oceans. The other half has a long lifetime, measured in centuries (and a fraction of that measured in millennia). Thus reducing emissions to zero would only produce a gradual reduction in the atmospheric CO2 level. Therefore active CO2 removal (CDR) is essential for quickly reducing that level to a safe value: somewhere in mid 300s of ppm.
Cheers, John (just back from holiday and a conference on ocean acidification) On Wed, Jun 3, 2015 at 1:00 AM, John Harte <jha...@berkeley.edu> wrote: > Recall that the natural sink strength today is about 4 or 5 Gt(C)/y … > there is no reason to think that this sink strength, which is effectively > driven by the difference between the current atmospheric concentration and > the concentration in an atmosphere in equilibrium with the current ocean > concentration, and which sink has been increasing since 1990, would rapidly > quench until the atmospheric concentration is well down into the mid 300's > ppm range. > > Hence if we reduce emissions down to a level of roughly 4 or 5 Gt(C)/y we > will see the atmospheric level roughly stabilize and if reduce emissions to > zero, we will see the atmospheric level drop at a very beneficial pace. > > What would invalidate this projection is crossing a tipping point in which > warming results in a sharp increase in background C or CH4 emissions > (effectively a negative sink) but the paleo record does not suggest that > such tipping points are lurking at current or even slightly higher > temperatures. > > If we do not reduce emissions, there is a of course a better chance that > we will cross such tipping points in the coming century. > > John Harte > Professor of Ecosystem Sciences > ERG/ESPM > 310 Barrows Hall > University of California > Berkeley, CA 94720 USA > jha...@berkeley.edu > > > > On May 31, 2015, at 8:39 PM, John Nissen <johnnissen2...@gmail.com> wrote: > > IPCC and the World bank ignore that we need ramp up removal technologies > until we are removing more CO2 than we are putting into the atmosphere. > This ramp up needs to start straight away, if we are to have a reasonable > chance of avoiding both dangerous global warming and dangerous ocean > acidification. CCS reduces emissions of CO2 into the atmosphere, but does > not actually remove CO2 as needed to get the level safely below 350 ppm or > so. > > There should be a formal complaint to IPCC about this, as for some other > issues. > > Cheers, John > > On Tue, May 26, 2015 at 8:53 AM, Schuiling, R.D. (Olaf) < > r.d.schuil...@uu.nl> wrote: > >> A serious lack of knowledge about natural processes. A million times more >> CO2 has been stored by nature in carbonate rocks than is present in the >> oceans, atmosphere and biosphere combined, and not a word about it, Olaf >> Schuiling >> >> -----Original Message----- >> From: geoengineering@googlegroups.com [mailto: >> geoengineering@googlegroups.com] On Behalf Of Greg Rau >> Sent: maandag 25 mei 2015 21:55 >> To: geoengineering@googlegroups.com >> Subject: [geo] World Bank report highlights necessity of (BE)CCS >> >> >> http://bellona.org/news/climate-change/2015-05-world-bank-report-highlights-necessity-ccs >> >> “We need Bio-CCS to attain carbon neutrality by 2100” >> >> "This statement forms a key area of scientific consensus, shared by the >> IPCC in the 5AR and acknowledged by the World Bank’s report. Achieving the >> 2°C target will necessitate negative emissions in the second part of this >> century. This can be achieved through the combination of sustainable >> bioenergy with CCS. Find out how it works here." >> >> GR - So says CCS promoters, completely ignoring numerous other C-negative >> technologies. >> >> "Importantly, the report warns that beyond 2030, the scenarios in which >> CCS is not available or not deployed at scale, the negative emissions >> required to keep temperature change below 2°C or even 3°C have to be >> generated from the agriculture, forestry, and other land-use sectors, >> creating immense challenges in land-use management." >> >> GR - Completely ignores ocean-based C-negative technologies. Who says >> that C-negative methods must be limited to <30% of the Earth's surface, >> much of which is already critical for other uses/services? >> >> "With regards to decarbonisation of the electricity sector, the report >> argues that the share of low-carbon or negative-carbon energy must rise >> from less than 20% in 2010 to about 60% in 2050. This is an increase of >> more than 300% over 40 years." >> >> GR- There is no way this is going to happen if we limit ourselves to >> making concentrated CO2 from flue gas and storing it in the ground - >> (BE)CCS. We need to expand RD&D, marketing and policy way beyond CCS. But >> how will this happen as long as well funded, vested interests continue to >> sell CCS as the only viable technology? >> >> "The report argues that oil and gas companies can in a similar fashion >> reinvent themselves if they develop CCS technology. A Bellona study has in >> fact found that the jobs and skills of today’s North Sea petroleum industry >> could largely be preserved when transformed into a CO2 storage industry." >> >> GR - At last, the real reason to promote CCS, whether or not it makes >> technical or economic sense and can compete with other technologies. The >> habitability of the planet held hostage by petroleum industry jobs. Sound >> familiar? >> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to geoengineering+unsubscr...@googlegroups.com. >> To post to this group, send email to geoengineering@googlegroups.com. >> Visit this group at http://groups.google.com/group/geoengineering. >> For more options, visit https://groups.google.com/d/optout. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to geoengineering+unsubscr...@googlegroups.com. >> To post to this group, send email to geoengineering@googlegroups.com. >> Visit this group at http://groups.google.com/group/geoengineering. >> For more options, visit https://groups.google.com/d/optout. >> > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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