The second part of the new IPCC report, about the impacts of climate change, has been released on Monday. Across the globe dutiful journalists filled the headlines of their newspapers – and as they presume most of their readers are human – focus heavily on the social implications, especially concerns for the human food supply, through a decrease in net agricultural productivity, firstly (from 1-2 degrees warming) in the tropics, and under current global emission trends (possibly even exceeding 4 degrees) also at high latitudes.

The authors conclude therefore that – as doubling of the current warming is already inevitable – the world climate policy should not just focus on reducing emissions, but also on adapting to warming – a message easily misinterpreted as ‘hey, I heard we can adapt, so that’s cool – with our lifestyle and economy and all’.

But written in between the lines of the summary for policy makers the report contains a much more dire warning – not a worry for its human inhabitants directly, but for the entire Earth, as a life-bearing planet: the Holocene Mass Extinction.

The above image shows a sudden rise in carbon concentrations due to massive methane/CO2 release at the end-Permian, 252 million years ago. Accompanied is a sudden drop in carbonate concentrations, a sign of CO2-induced ocean acidification. Paleoclimatology shows there are certain things you cannot adapt to.

How much biodiversity will an already ecologically stressed Earth lose to the disruption of one degree warming, how much to 2 degrees, how much to 3, 4, and beyond? – no one knows! There are model calculations showing that within this century up to 84 percent of intraspecific biodiversity will be lost as a consequence of climate change, a full-swing mass extinction that is, mainly caused by ecological tipping points and a shift in biomes.

To get a feeling of why species may not survive a couple degrees warming, one has to zoom into the ecosystem level and closely observe the impacts of skewed changes – that is changes that do not lead to a homogeneous response (a ‘joint shift of the equilibrium’) but a shift that is distorted between for instance seasons, rainfall versus temperature or predator-prey.

Here is just a short quotation from Chapter 4 – Terrestrial and Inland Water Systems – of the new WG2 IPCC AR5 report, to illustrate the latter:

“Bird breeding can also be affected by phenological shifts in competing species and predators. Between 1953 and 2005 in south-western Finland, the onset of breeding of the resident great tit Parus major and the migratory pied flycatcher (Ficedula hypoleuca) became closer to each other, increasing competition between them (Ahola et al., 2007). The edible dormouse (Glis glis), a nest predator, advanced its hibernation termination by -8 days per decade
in the Czech Republic between 1980 and 2005 due to increasing annual spring air temperatures, leading to increased nest predation in three out of four bird surveyed species (Adamik and Kral, 2008). Plant-insect interactions have also been observed to change. In Illinois, USA, the pattern of which plants were pollinated by which bees were altered by differing rates of phenological shifts and landscape changes over 120 years, with 50% of bee species becoming locally extinct (Burkle et al., 2013). Increasing asynchrony of the winter moth (Operophtera brumata) and its feeding host oak tree (Quercus robur) in the Netherlands was linked to increasing spring temperatures but unchanging winter temperatures (van Asch and Visser, 2007). Warmer temperatures shorten the development period of European pine sawfly larvae (Neodiprion sertifer Geoffr.), reducing the risk of predation and potentially increasing the risk of insect outbreaks, but interactions with other factors including day length and food quality may complicate this prediction (Kollberg et al., 2013). In North America, the spruce budworm (Choristaneura fumiferana) lays eggs with a wide range of emergence timings, so the population as a whole is less sensitive to changing phenology of host trees (Volney and Fleming, 2007).”

Now let’s go 250 million years back in time. Or to February 2014 if you like, when an MIT research group published their findings in PNAS – in a study they called ‘Methanogenic burst in the end-Permian carbon cycle’.

As our regulars are well aware in that one single chapter of the 5 billion page history of Earth something extraordinary happened – the planetary disaster was set in place that almost the entirety of life did not survive: the Permian-Triassic Mass Extinction.

[Sometimes, we wonder, what would have happened if indeed the end-Permian catastrophe would have been bigger still and Earth would have become fully lifeless from that point (which is after all the norm for planets around us!) – we would have a so-much more powerful analogue at hand. Then again of course we could not have drawn it. Complicated stuff..!]

Many scientists have wondered what exactly caused that extremely powerful blow to life. The fossil record shows it coincided with massive volcanic activity in Siberia, which released large amounts of CO2 and other pollutants to the atmosphere and oceans.

Continued research has already shown that this was probably not the weapon, but the trigger – to a cascade of life-disrupting events. One of these was the sudden dominance of a methane-producing bacterium, Methanosarcina, that fed on the volcanic pollution in the oceans. A sudden explosion of this mutating bacterium – indeed a plague – in ever more poisoned oceans led to an enormous release of methane to the atmosphere.

And while these ocean-floating bacteria created the methane disaster that warmed the planet, disrupted ecosystems, led to further CO2 rise and ocean acidification – another killer microbe finished the job on land, wiping out the still-standing forests.

Now we ask, how does one adapt to such unpredictable climate impacts?

We have to focus on the physical core of the matter: carbon emissions – and stabilising its atmospheric concentrations as fast as possible. The hoped new UN climate treaty of 2015, to be agreed on during the big climate summit in Paris that year will therefore have to be about one thing primarily: ambitious emission targets.

© Rolf Schuttenhelm | www.bitsofscience.org