drought

Chilean lake turns to desert, sounding climate change alarm

Chilean lake turns to desert, sounding climate change alarm

Lake in Chile is disappearing:

The Penuelas reservoir in central Chile was until twenty years ago the main source of water for the city of Valparaiso, holding enough water for 38,000 Olympic-size swimming pools. Water for only two pools now remains.

Normally, low-pressure storms from the Pacific unload precipitation over Chile in winter, recharging aquifers and packing the Andes mountains with snow.

But naturally occurring warming of the sea off Chile’s coast, which blocks storms from arriving, has been intensified by rising global sea temperature, according to a global study on sea temperature and rainfall deficits. Ozone depletion and greenhouse gasses in the Antarctic, meanwhile, exacerbate weather patterns that draw storms away from Chile, according to a study on variables affecting Antarctic weather.

Analysis of tree rings going back 400 years shows how rare the current drought is[…]. It is totally unrivalled for duration or intensity.

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Is the world going to run out of water?

Is the world going to run out of water?

Good read, but only focused on the consumption side. The viewpoint missing for me is that we totally mismanage the water infiltration potential.

In many places the answer is yes – if we continue as we have done. The rest of the world could learn a lot from Denmark, one of the few countries to have reduced its water consumption.

Danish water consumption today is approximately 40 percent lower than it was in 1980 (see graph 3), and it is still decreasing. Denmark managed to reduce the curve through a combination of greatly increased water prices (including green taxes), water saving campaigns, more water efficient technology in households and industry, and a reduction of water loss from the mains supply.

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Spain and Portugal suffering driest climate for 1,200 years, research shows

Spain and Portugal suffering driest climate for 1,200 years, research shows

Puhh….

Most rain on the Iberian peninsula falls in winter as wet, low-pressure systems blow in from the Atlantic. But a high-pressure system off the coast, called the Azores high, can block the wet weather fronts.

The researchers found that winters featuring “extremely large” Azores highs have increased dramatically from one winter in 10 before 1850 to one in four since 1980. These extremes also push the wet weather northwards, making downpours in the northern UK and Scandinavia more likely.

The scientists said the more frequent large Azores highs could only have been caused by the climate crisis, caused by humanity’s carbon emissions.

“The number of extremely large Azores highs in the last 100 years is really unprecedented when you look at the previous 1,000 years,” said Dr Caroline Ummenhofer, at Woods Hole Oceanographic Institution in the US

“[Our findings] have big implications for the water resources that are available for agriculture and other water intensive industries or for tourism,” said Ummenhofer. “It doesn’t bode well.”

Research in 2021 also linked the Azores high to the summer monsoon in India.

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Differences in temperature on open and vegetated soils

Differences in temperature on open and vegetated soils

Yesterday, at gentle 24 ° C air temperature, I measured the soil surface temperatures (for the first time). On the areas with open soil in the corn field of our neighbour: over 50°C. In the clover grass on our side: 26°C.

It’s amazing how the soil heats up (and was another 6°C warmer than the (rough) road next to it). Problematic not only for the soil life, soil water and for many crops. Also not good for the climate, because of warming of air temperature in this area, increased heat radiation, on larger areas potential development of high pressure areas, possible reduction of precipitation, … For more see my UNEP article and presentation, and the Climate Landscapes conference.

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Summer soil drying exacerbated by earlier spring greening of northern vegetation

Summer soil drying exacerbated by earlier spring greening of northern vegetation

Interesting article:

Earlier vegetation greening under climate change raises evapotranspiration and thus lowers spring soil moisture. […] We provide observational evidence that increased foliage cover over the Northern Hemisphere, during 1982–2011, triggers an additional soil moisture deficit that is further carried over into summer. […] attribute the driving process to be larger increases in evapotranspiration than in precipitation. This extra soil drying is projected to amplify the frequency and intensity of summer heatwaves. Most feedbacks operate locally, except for a notable teleconnection where extra moisture transpired over Europe is transported to central Siberia. Model results illustrate that this teleconnection offsets Siberian soil moisture losses from local spring greening.

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The longest river in Italy is drying up. What does this mean for those who rely on it for food?

The longest river in Italy is drying up. What does this mean for those who rely on it for food?

“Italy’s Po River flows some 650km from the snowy Alps in the northwest to the wild Po Delta in the east before rushing out into the Adriatic Sea.

During its course, the great waterway nourishes the expansive fertile plains of northern Italy where farmers have thrived for generations. Dubbed Italy’s breadbasket, these flatlands covered with crops are responsible for some 40 per cent of Italy’s GDP.

At the moment, however, the normally life-giving waters of the Po River have suddenly become an unexpected threat. The dramatically low water levels of the river have been causing seawater to be sucked back upstream.”

Source: Euronews

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H2O – The molecule that made us

H2O – The molecule that made us

Very interesting documentary with impressive pictures around the big problem of dwindling water: “Water is the prerequisite for life. A few tiny drops are already enough to make a withered desert blossom anew. Water also played an important role in the emergence of early civilizations. Control of the resource gave humans clear advantages. But access to clean water is becoming increasingly difficult, and fear for the resource is growing. – A documentary series tracing our relationship with the “blue gold.””

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Drought self-propagation in drylands due to land–atmosphere feedbacks

Drought self-propagation in drylands due to land–atmosphere feedbacks

It has consequences, if (agricultural or forest) soils can hold less and less water and dry out. Although this research is on global drylands, I dare to guess that the same pattern applies to our desiccating agricultural landscapes.

Reduced evaporation due to dry soils can affect the land surface energy balance, with implications for local and downwind precipitation. […] We show that dryland droughts are particularly prone to self-propagating because evaporation tends to respond strongly to enhanced soil water stress. In drylands, precipitation can decline by more than 15% due to upwind drought during a single event and up to 30% during individual months. In light of projected widespread reductions in water availability, this feedback may further exacerbate future droughts.

Description of the figure: »Meteorological drought is frequently triggered by weaker-than-usual dynamical saturation-enabling mechanisms (conceptualized as low precipitation efficiency; Peffʹ < 0), which in turn may respond to a remote forcing, such as anomalous sea surface temperatures. Once that happens, limited precipitation (Pʹ < 0) causes soil desiccation (SMʹ < 0) and soil stress, exacerbated by the high potential evaporation due to clear skies and elevated temperatures. Then, evaporation becomes (more) water limited (E’ < 0). The reduction in near-surface air moistening — extending across the troposphere via vertical mixing—causes a reduction in water vapour being exported downwind (Qʹ < 0). Therefore, further downwind, for the same precipitation efficiency, even less precipitation is expected (Pʹ < 0), contributing to downwind drought onset (SMʹ < 0, Eʹ < 0). Moreover, since water vapour is known to enhance uplift, additional reductions are possible for convective precipitation (Peffʹ, Pʹ, SMʹ, Eʹ « 0).«

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