HAMNET Report 30th July 2023

Since Monday, the top end of the Philippines, the bottom end of Taiwan, and the Chinese mainland in between, have been threatened by a new tropical cyclone called DOKSURI, or EGAY by the Philippine citizens. Bearing from south-east in the direction of north-west, it was expected to clip the two island nations before hitting the Chinese coast, with wind speeds of up to 240km/h. The numbers of people in the area threatened by winds of at least 120km/h were estimated at nearly 23 million by Friday. Sixteen deaths were reported from Philippines by Friday, with twenty more missing.

Parts of Taiwan and coastal mainland China are expected to experience heavy downpours of between 250 and 400mm of rain before the storm is over.

Meanwhile there is now an orange alert for Tropical Cyclone KHANUN, active in the north-west Pacific, and threatening Japan and China. Preliminary forecasts suggest maximum wind speeds of 160km/h, with as many as 42 million people within the cone of its 120km/h winds.

And of course, the south-western and southern parts of our country are in the grip of a major cold front, and its following cold air. News24.com says that Western Cape Disaster Risk Management teams are on high alert after warnings were issued for cold and wet weather over the weekend.

The head of the Western Cape’s disaster management service, Colin Diener, said teams were preparing for heavy rains, strong coastal winds, low temperatures and snowfall.

“We are specifically concerned about areas in the Overstrand and Garden Route districts, and snowfall in high-lying areas. People should rather postpone outdoor plans for this weekend,” he said.

Diener added that the provincial government was speaking to nature conservation organisations about closing some walking and hiking routes in the province.

The South African Weather Service issued warnings for “disruptive rainfall” and “damaging waves”.

A strong cold front, accompanied by snowfall and heavy rainfall, made landfall on Friday evening along the country’s west coast. Heavy rainfall was expected to lead to flooding over parts of Cape Town, the Cape Winelands, as well as the Overberg and Garden Route districts.

Snowfall is expected across the interior mountain ranges of the Western Cape. Very cold conditions, with maximum temperatures of between 5°C and 10°C, are expected over the interior from Saturday and into Sunday. Snow is also expected over the Eastern Cape Mountains spreading to the Drakensberg and Lesotho.

High seas with wave heights between 6 and 7 metres are expected along the south coast of the Western Cape from yesterday and into today.

Now space.com has a worrying story in the “climate decay” category. (That is, if you are not one of the folk who believe we have nothing to do with climate change.) They say that a major system of ocean currents that ferries heat from the tropics to the North Atlantic could shut down far sooner than expected, according to new predictions. Such a collapse would prove catastrophic for Earth’s climate.

The system, known as the Atlantic Meridional Overturning Circulation (AMOC) had previously been measured to be dramatically weakening in conjunction with rising ocean temperatures. Despite this, however, the Intergovernmental Panel on Climate Change (IPCC) recently announced that climate scientists don’t expect the AMOC to totally switch off within the century. 

But a new study is now challenging that conclusion, raising the spectre of a halted AMOC to as early as 2025.

“Shutting down the AMOC can have very serious consequences for Earth’s climate, for example, by changing how heat and precipitation are distributed globally,” study leader Peter Ditlevsen, from the Niels Bohr Institute at the University of Copenhagen, said in a statement.

Finding that direct measurements of the AMOC’s strength have only been made for the past 15 years, Ditlevsen’s team applied sophisticated statistical tools to ocean temperature data going all the way back to the 1870s for an enhanced dataset. This detailed analysis ultimately suggested significant warning signs of the AMOC shutting down between 2025 and 2095, with a staggering certainty of 95%. More specifically, the team’s results evidenced that the most likely time for this collapse would be around 2057.

Still, other climate scientists remain cautious, saying that there are still uncertainties in the data that could affect its accuracy. However, it’s worth considering that even the mere possibility of the AMOC shutting down so soon is rather alarming.

The AMOC, which includes the Gulf Stream as part of its system, is our planet’s main mode of transporting heat away from the tropics. Without it, the tropics would rapidly increase in temperature while vital tropical rains would get disrupted. Such rains are essential for the environments of South America, western Africa as well as in India and other regions of south Asia.

Meanwhile, northern and western Europe would lose their source of warm water from the tropics, leading to more storms and severely cold winters in these areas. The loss of the Gulf Stream in particular would also result in rising sea levels on the US eastern seaboard. 

“Our result underscores the importance of reducing global greenhouse gas emissions as soon as possible,” Ditlevsen said.

In recent years, we’ve already seen the dangers of human-induced climate warming play out as heatwaves grip much of the northern hemisphere. And although the loss of the AMOC may see northern and western Europe cool, “this shutdown will contribute to an increased warming of the tropics,” Ditlevsen said, “where rising temperatures have already given rise to challenging living conditions.”

The findings were published on Tuesday (25th of July) in the journal Nature Communications.

NASA, in its newsletter of this week, says that they and the Defense Advanced Research Projects Agency (DARPA) have announced Lockheed Martin as the prime contractor for the design, integration, and testing of a nuclear-powered rocket demonstration.

The Demonstration Rocket for Agile Cislunar Operations (DRACO) program will test a nuclear-powered rocket in space as soon as 2027. The partnership will advance the development of nuclear thermal rocket technology, supporting both agencies’ goals.

For NASA, nuclear propulsion is one of the primary capabilities on the roadmap for crewed missions to Mars. A nuclear-powered rocket would allow for a shorter, faster trip to the Red Planet, reducing the mission’s complexity and risk for the crew. This type of rocket can be more than twice as efficient as conventional chemical rockets, meaning it requires significantly less propellant and could carry more equipment for scientific goals.

This is Dave Reece ZS1DFR, celebrating what would have been my Father’s 117th birthday today, and reporting for HAMNET in South Africa.