Climate Letter #1310

What would happen if temperatures actually rose by 5-6C in this century, as some are forecasting?  This new study, using thousands of complex computer models, paid particular attention to climate impacts on plants and animals in their wild state.  The research was basically interested in searching for domino-type effects, where losses of some species contribute to the losses of others, an effect found to be surprisingly elevated.  “The study also explored the worst possible scenario of temperature change due to global warming.  According to the simulations, 5-6°C of warming would be enough to wipe out most life on the virtual Earths the scientists created.”  From a general appraisal of the research, “our results are consistent with real-world patterns for which we have empirical evidence…..What is clear is that a warming Earth will put increasing pressure on the planet’s biodiversity, and co-extinctions will add to that impact.”

—–

The Little Ice Age could return to the Northern Hemisphere.  That possibility is suggested by a new a new study that has found convincing evidence that the overturning of Atlantic circulation (AMOC) has weakened over the last 1500 years, something also indicated by other theories and measurements of varying credibility.  The weakening occurs episodically, and one such event has been pictured as the cause of an extended cold spell between 1600 and 1850 that was most dramatically effective across Europe.  (Events like this can temporarily cool part of the Earth, but any such temperature effect can also be offset by other factors, like a rise of greenhouse gases.)

—–

Bushfires in Australia have caused thousands to evacuate as temperature records are broken.  “The Bureau of Meteorology declared a “catastrophic” fire danger—the highest possible risk rating—in some central areas, while firefighters battled to contain more than 130 blazes across the state.”
https://phys.org/news/2018-11-thousands-evacuated-australian-bushfires-rage.html

—–

The UN has issued an “Emissions Gap Report 2018” prior to the major conference in Poland that starts next week (BBC News).  It shows how far off track the trend is running, with the peak presently not expected until around 2030, and gives many of the reasons why this is so, emphasizing the high level of economic growth.  “The report also suggests that government tax plans could be hugely important in tackling emissions…..If all fossil fuel subsidies were phased out, global carbon emissions could be reduced by up to 10% by 2030. Setting the right carbon price is also essential. At $70 per tonne of CO2, emission reductions of up to 40% are possible in some countries.”  Those are things that can be done, if there is a will.

—–