Guest post by John Crusius, Richard Gammon, and Steve Emerson
The scientific community is almost universally in agreement that climate change (and ocean acidification) are severe threats that demand a rapid response, with putting a price on fossil fuel CO2 emissions being a top priority. Far and away the single biggest contributor to climate change is CO2 emissions from fossil fuel combustion. Indeed, global CO2 emissions from fossil fuel emissions in recent years have been roughly ten times higher than emissions from the next largest global source, land use change, including deforestation (Le Quéré et al., 2015). Despite the small size of carbon fluxes from forests, enhancing carbon storage in forests is often discussed in WA state as a tool to fight climate change. There was one such claim in the Seattle Times OpEd from October 21 by Mathew Randazzo. We challenge these claims that forest carbon sequestration in WA state can significantly help solve climate change. Randazzo does not spell out in any detail what he means. As always, details matter in such discussions, as the science is complex. We focus here on some of the best available science on the climate and carbon storage impacts of forests, and provide references at the bottom of this article from some of the premier scientific journals in the world.
There is an interesting news article ($) in Science this week by Paul Voosen on the increasing amount of transparency on climate model tuning. (Full disclosure, I spoke to him a couple of times for this article and I’m working on tuning description paper for the US climate modeling centers). The main points of the article are worth highlighting here, even if a few of the characterizations are slightly off.
Last weekend, in Reykjavik the Arctic Circle Assembly was held, the large annual conference on all aspects of the Arctic. A topic of this year was: What’s going on in the North Atlantic? This referred to the conspicuous ‘cold blob’ in the subpolar Atlantic, on which there were lectures and a panel discussion (Reykjavik University had invited me to give one of the talks). Here I want to provide a brief overview of the issues discussed.
What is the ‘cold blob’?
This refers to exceptionally cold water in the subpolar Atlantic south of Greenland. In our paper last year we have shown it like this (see also our RealClimate post about it):
Nature published a great new reconstruction of global temperatures over the past 2 million years today. Snyder (2016) uses 61 temperature reconstructions from 59 globally diverse sediment cores and a correlation structure from model simulations of the last glacial maximum to estimate (with uncertainties) the history of global temperature back through the last few dozen ice ages cycles. There are multiple real things to discuss about this – the methodology, the relatively small number of cores being used (compared to what could have been analyzed), the age modeling etc. – and many interesting applications – constraints on polar amplification, the mid-Pleistocene transition, the duration and nature of previous interglacials – but unfortunately, the bulk of the attention will be paid to a specific (erroneous) claim about Earth System Sensitivity (ESS) that made it into the abstract and was the lead conclusion in the press release.
The paper claims that ESS is ~9ºC and that this implies that the long term committed warming from today’s CO2 levels is a further 3-7ºC. This is simply wrong.