Category Archives: Impacts Observed & Projected

PLEA Network

23 June 2015, The Carbon Brief, Solar minimum could bring cold winters to Europe and US, but would not hold off climate change. Over the past few decades, our Sun has been relatively active, giving off high levels of the solar radiation that warms the Earth. However, in recent years this peak activity has tailed off, prompting scientists to wonder if the Sun is heading into a period of lower output. A new study says even if the Sun’s activity did drop off for a while, it wouldn’t have much impact on rising global temperatures. But it could mean a higher chance of a chilly winter in Europe and the US, the researchers say.

The Sun’s activity rises and falls on an approximately 11-year cycle, but it can experience longer variations from one century to another. Over the past 10,000 years, the Sun has hit around 30 periods of very high or very low activity – called ‘grand maxima’ and ‘grand minima’. One of these occurred between 1645 and 1715, when the Sun went through a prolonged spell of low solar activity, known as the Maunder Minimum. This didn’t have much of an effect on global climate, but it was linked to a number of very cold winters in Europe. In 2010, scientists predicted an 8% chance that we could return to Maunder Minimum conditions within the next 40 years.

But since that study was published, solar activity has declined further, and this likelihood has increased to 15 or 20%, says new research published today in open-access journal Nature Communications. In fact, the Sun’s output has declined faster than any time in our 9,300-year record, say the researchers. And so they set out to analyse what this could mean for global and regional climate. The researchers used a climate model to run two scenarios where solar activity declines to a grand minimum. They then compared the results with a control scenario where the Sun continues on its regular cycle. For all model runs they used the RCP8.5 scenario to account for future climate change – this is the scenario with the highest greenhouse gas emissions of those used by the Intergovernmental Panel on Climate Change ( IPCC). Global emissions are currently tracking just above this scenario. Read More here

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22 June 2015, The Carbon Brief, Climate change attribution studies are asking the wrong questions, study says. Scientists are calling for a rethink in the way we seek to understand how climate change affects extreme weather. The latest in so-called attribution studies is to study each individual event by itself, looking for how climate change may have made it stronger or more likely. But a new paper says the methods used in many of these studies underestimate the influence of climate change, and suggests a new approach to identify the “true likelihood of human influence”.

One of the first studies to attribute a single extreme weather event to climate change was published just over a decade ago. Researchers showed that climate change had doubled the chances of the record heatwave Europe experienced in 2003. In the years that followed, many more studies have aimed to provide answers on how climate change is affecting our most brutal weather. But while scientists have been able to attribute events caused by temperature extremes, linking other extreme events like storms and heavy rainfall events has proved more difficult, says a new paper in Nature Climate Change. Read More here

PLEA Network

22 June 2015, The Conversation, Climate: the elephant in the room for developing northern Australia: The recently released white paper on developing northern Australia ignores an elephant in the room: climate change. While the paper sees a bright future for the north (roads, rail, dams and food), without considering climate change we can’t be sure the north will even be liveable. The white paper also fails to take into account other environmental constraints such as water and soils….. The white paper has not referenced high-quality expert advice prepared by the Northern Australian Land and Water Task Force…. The white paper ignores reference to sophisticated climate change projections for northern Australia developed by our own CSIRO and Bureau of Meteorology. Climate projections for the north this century paint a dire future and bring into question the feasibility and affordability of many of the development policies, plans and projects outlined in the white paper. Read More here

 

PLEA Network

19 June 2015, Carbon Brief, The Atlantic ‘conveyor belt’ and climate: 10 years of the RAPID project: A global project that’s been instrumental in shaping scientists’ understanding of how the oceans affect our climate celebrated its tenth birthday recently. A new paper published in Science looks back at 10 years of the RAPID project, which has been keeping tabs on how heat moves around in the Atlantic Ocean since 2004. Over its short lifetime, the project has thrown up a few surprises. Parts of the Atlantic circulation seem to have slowed down, though whether that’s down to human activity remains to be seen. Carbon Brief talks to one of RAPID’s founding scientists, Prof Harry Bryden from the National Oceanography Centre in Southampton, about the project. Read More here

Global heat transport

Above about 1,000 metres in the North Atlantic, warm water flows northwards from the equator towards the poles, releasing heat as it goes. The water cools and sinks at high latitudes, returning southwards towards the equator at much deeper depths.

This is known as the Atlantic Meridional Overturning Circulation (AMOC) and forms part of aglobal ocean conveyor belt that transports heat all around the world.

                 Screenshot 2015-06-19 18.22.21

The Atlantic Meridional Overturning Circulation (AMOC). Warm water flows north in the upper ocean (red arrows) then sinks and returns south as deep cold water (blue arrows) Source: Srokosz & Bryden ( 2015) Supplementary material