Climate change items of note

Nature has got three stories of interest about climate change at the moment:

1. a report summarising some of the complexities and uncertainties in studies about the fate of the Amazon rainforest.

2. the US National Research Council has put out a report which :

sets out the consequences — from streamflow and wildfires to crop productivity and sea level rise — of different greenhouse-gas emissions scenarios. It also concludes that once the global average temperature warms beyond a certain point, Earth and future generations will be stuck with significant impacts for centuries or millennia.

That seems quite a big ask. But they seem confident based on more recent work since the last IPCC reports:

Besides synthesizing data included in the Fourth Assessment Report released by the Intergovernmental Panel on Climate Change in 2007, the NRC report includes new information. For example, carbon-dioxide-induced warming is expected to be nearly irreversible for at least 1,000 years, according to two studies published in 2008 and 2009 (refs ^2,3). "There is more certainty [in this report] than we've seen before," says Steve Cohen, executive director of the Earth Institute at Columbia University in New York City. "It is blunt, direct and clear. Unlike the IPCC reports you don't see any hedge words."

And what do they find?:

....the report shows that each 1 °C of warming will reduce rain in the southwest of North America, the Mediterranean and southern Africa by 5–10%; cut yields of some crops, including maize (corn) and wheat, by 5–15%; and increase the area burned by wildfires in the western United States by 200–400%. The report also points out that even if the atmospheric concentration of carbon dioxide is stabilized, the world will continue to warm for decades. If concentrations rose to 550 parts per million, for example, the world would see an initial warming of 1.6 °C — but even if concentrations stabilized at this level, further warming would leave the total temperature rise closer to 3 °C, and would persist for millennia.

Bad, bad predictions for our descendants, that's for sure. Which will be studiously ignored by most Australian politicians. Bah.

3. OK, so we'll geoengineer our way out of trouble? Not so fast. A study that has tried to model the effects of pumping lots of sulphate aerosols high into the atmosphere says it won't work uniformly across the globe:

In a paper published today in Nature Geoscience¹, Kate Ricke, a climate physicist at Carnegie Mellon University in Pittsburgh, Pennsylvania, and her colleagues show, by modelling, that not only could solar-radiation management lead to declines in rainfall in the long term, but its effects will also vary by region. Some places will be over-cooled by atmospheric changes that are too small to be effective for their neighbours....

The new study found that it is fairly easy to design sulphate-injection scenarios that keep the temperature stable until 2080. But, unfortunately, the change in sunlight alters other weather patterns. "It changes the distribution of energy in the troposphere so that it becomes more convectively stable," Ricke says. The result: decreasing precipitation.

Better to keep carbon down, then.