JON CARTWRIGHT

The “Day Zero” water crisis that threatened the city of Cape Town in South Africa last year was due to an expansion of stable conditions in the subtropics that pushed rainfall farther south, according to a meteorological analysis. The researchers believe their study highlights the vulnerability of the Cape Town area – and other areas with dry, Mediterranean-type climates – to climate change.

“Although droughts are relatively frequent in these areas, the severity and frequency of occurrence in regions like Cape Town, California [in the US] and the Iberian Peninsula [in south-west Europe], among others, appears to be rising,” says Pedro Sousa of the University of Lisbon in Portugal. “This has been particularly notable in the last few years, which correspond exactly to the warmest years ever observed at the global scale.” […]

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Besides electricity consumption, the indirect emissions of supply chains are the fastest-rising area of emissions worldwide, according to researchers in the US and Norway.

In the two decades to 2015, such indirect emissions rose by over 80% – nearly double the rise of direct emissions. The non-electrical indirect emissions of the industry sector alone now stand at 32 billion tonnes of carbon dioxide, the study shows.

Edgar Hertwich at Yale University, US, believes his and colleagues’ study exposes “the potential agency different sectors have over supply chain emissions”. The message is to “look at your purchases in addition to your direct energy consumption, to identify opportunities for emission reductions”.

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A common maxim about climate change says that wet places will grow wetter, while dry places will dry more. A recent study by US scientists suggests that, when it comes to effects on humanity, rising dryness will be key.

“We show that although some regions do get wetter, many of those are sparsely populated,” says Megan Lickley of the Massachusetts Institute of Technology (MIT), US. “So from the viewpoint of humanity, ‘wet-get-wetter, dry-get-drier’ doesn’t characterize our human future, which is [actually] heavily dominated by drying.”

By 2100, half the world’s population will live in regions where dryness has risen by at least 5%, Lickley and colleague Susan Solomon showed. Assuming a high, “business as usual” emissions scenario, areas that are technically arid will be home to 700 million more people than today.

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Flood models tested in the first collective validation captured between 52 and 97% of flooded areas for two flood events and three areas in Nigeria and Mozambique. This result was “better than expected”, according to the research team.

“These models have shown a level of performance that allows them to be used for large-scale questions, like identifying the regions of highest flood risk globally,” says Mark Bernhofen of the University of Leeds, UK. “The majority of the models performed fairly well.”

In the decade leading up to 2015, floods killed an estimated 157,000 people worldwide, and affected 2.3 billion in total. As climate changes, the number of people exposed to river flooding over the next three decades is likely to rise by over 30%. […]

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Tropical cyclones over the western North Pacific underwent a “regime shift” in their destructive potential in 1998, according to researchers in China.

In their study of the years 1979 to 2016, the destructiveness of the cyclones increased rapidly after 1998, rising 97% from the interval 1998–2003 to 2012–2016.

The researchers believe the shift results from the impacts of the strong La Niña weather phenomenon of 1998–2001, and the strong El Niño in 2014–2016.

Tropical cyclones in the western North Pacific have caused immense damage, disruption and loss of life. In 2013, for example, Typhoon Haiyan became the deadliest Philippine typhoon on record, killing over 6,000 people. Haiyan also holds the joint record for strongest tropical cyclone to hit land. […]

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A plan by the Egyptian government to make the country self-sufficient in wheat will likely fail by the 2040s, according to a study by researchers in Egypt and the US.

The plan involves intensifying farming methods and the near-doubling of irrigated land for wheat production by 2035, from 3.9 to 7.7 million hectares. According to the study, however, even a modest growth in population will swiftly consume the extra yield from this expansion.

“As about 30% of wheat is irrigated globally, the challenges Egypt is facing are similar to other countries trying to increase agricultural production,” says Senthold Asseng of the University of Florida, US. “What we learn from our study in Egypt will also apply to other parts of the world.”

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The installation of green roofs in cities to reduce the “urban heat island” effect should take into account which areas are hottest, which people are most vulnerable and where air-conditioning usage is highest, say researchers in the US. The effect describes the heightened air temperatures of cities relative to the surrounding countryside.

Using computer models to include all these factors, the researchers found that in the US city of Chicago, areas to the south and west, as well as certain other isolated areas, would benefit most from green roof installation.

The methodology can and should be applied to other places that suffer from the urban heat island effect, the researchers say.

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Along the US east coast, offshore wind power would have the greatest market value off New York, Connecticut, Rhode Island and Massachusetts. That’s according to US researchers who developed a method to assess the economic value of potential offshore wind sites.

The technique shows that the market value of offshore wind could vary from $40 to more than $110 per megawatt-hour. It included the influence of factors such as renewable energy credits

“What we are trying to provide is relevant information to policy makers and to the public and to developers,” says Dev Millstein of Lawrence Berkeley National Laboratory. “The idea is that this information will help each region make informed decisions about policies related to offshore wind development.” […]

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