In early 2024 most parts of Kenya, including Nairobi, experienced unusually high temperatures. The World Meteorological Organisation described the hot weather as a global phenomenon: record high temperatures were recorded in 2023. January 2024 has been recorded as the hottest month on record so far worldwide. Gilbert Ouma, the coordinator of the University of Nairobi’s Institute for Climate Change and Adaptation, and an associate professor at the Department of Meteorology, answers some key questions.

What is unusual about the weather in Nairobi?

The annual average temperatures for Nairobi are normally moderate, between 24°C and 25°C on the higher side and 17°C-18°C on the lower side. These are generally very comfortable temperatures. However, in the December-January-February period, maximum temperatures are normally high, ranging between 26°C and 27°C.

This year, temperatures in February went up to between 29°C and 30°C, even hitting 31°C. This is about 6°C higher than normal Nairobi temperatures. That is a big difference and our bodies are bound to feel the difference. If such an increase is sustained for a long time, it can lead to a heat wave.

But in Nairobi’s case, the high temperatures have been on and off, so we can’t really talk of a heat wave. What Nairobi has had is a wave of hot weather that the human body can easily adjust to.

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Why is the weather suddenly hot?

The winds that pass over Kenya from December to February every year are from the north. They blow mainly through continental areas, including some deserts. These winds flow in waves and periodically bring hot weather, the kind that has prevailed recently across east Africa.

The temperatures that are prevailing in Kenya are also dictated by the path that the winds take from the north. If the path is straight (over land mass), then we end up with these high temperatures that we have experienced in the early months of 2024. If the winds follow a path that curves into the Indian Ocean, then the temperatures get moderated, resulting in cooler weather and rainfall in Kenya and other parts of east Africa.

Also, because of climate change, average global temperatures are rising. The temperatures last year were the highest on record. So the relatively high temperatures that we normally experience during this season (December-January-February) may be considerably higher.

Another thing to note is that the December to February season is always a dry season in Kenya, but December and January of 2024 were wet because of the late el Niño rains. The el Niño phenomenon is normally experienced in this region within the September-October-November season. The temperatures which were supposed to be high in December and January were therefore moderated by those rains. So, when the rains ceased, the usual heat suddenly set in, making February feel very hot.

Kenya and its eastern African neighbours have all experienced the hot weather. The region is now moving towards the March-April-May season when the rainfall belt comes back around the equator and the sun will be overhead. The rainfall is expected to moderate the high temperatures.

What’s the effect of rising temperatures?

Aside from the hot weather at this time of year, the global climate is changing and average global temperatures are rising. The annual temperature for Africa has been increasing at an average rate of 0.13°C per decade since 1910, but this has more than doubled to 0.28°C since 1981. The normal minimum temperatures and the maximum temperatures are rising. This will lead to changes in extremes, such as storms. A storm is a way that the atmosphere discharges excess energy to regain equilibrium. When the energy builds in the atmosphere up to over certain levels, the excess has to go somewhere. The excess energy build-up due to the greenhouse gas effect, which leads to climate change, requires dissipation. This is usually achieved through intense storms, leading to more frequent extreme rainfall events. On the other hand, the other extreme of very low rainfall will also occur, and so we will get more droughts. The total amount of rains will go up in some places and down in others.

There will also be an impact on ecosystems. A number of species will not survive the changing climate. For instance, mosquitoes cannot thrive in temperatures below 17°C and above 35°C. So when the average temperatures of places go beyond this range, mosquitoes would find it difficult to survive. However, the temperatures of some places whose temperatures were not within this range may change and get within it. For such places, malaria will become a problem when previously there was no malaria there.

The long term effect would be bad on people’s health. It could lead to heat stroke and chronic conditions such kidney disease, hypertension and cardiovascular disease. It could also cause respiratory problems such as asthma.

Researchers present the world's oldest long-necked marine reptile
The fossil of the long-necked marine reptile Trachelosaurus fischeri. Credit: SMNS, Liliana Reinöhl

An international team of scientists led by Dr. Stephan Spiekman, Dr. Eudald Mujal and Prof. Dr. Rainer Schoch, paleontologists at the State Museum of Natural History Stuttgart, has re-examined the fossil of the reptile Trachelosaurus fischeri, which was first described at the beginning of the 20th century.

Comparisons with new fossil finds of a similar marine reptile from China show that Trachelosaurus fischeri is the world’s oldest long-necked marine reptile. The scientists have published their research findings on the 247-million-year-old fossil from Sachsen-Anhalt, Gemany, in the Swiss Journal of Palaeontology.

Trachelosaurus fischeri was already discovered back in the 19th century in layers of Buntsandstein (Middle Triassic) in Bernburg an der Saale, Germany, and it was subsequently added to the collection of Martin Luther University Halle-Wittenberg. The specimen is currently on loan to the State Museum of Natural History Stuttgart, where it was re-examined by specialists.

Trachelosaurus fischeri was first described in a publication in 1918, but controversy remained as to what kind of reptile this fossil actually represented. This is because Trachelosaurus fischeri has a unique anatomy, including an unusually large number of vertebrae, and because of the relatively poor preservation of the fossil: The skeleton is incomplete and its remains are scattered all over the rock in which it was preserved.

“Through research on Chinese fossils of the long-necked marine reptile Dinocephalosaurus, which I published with colleagues just a few weeks ago, we were able to solve the mystery of Trachelosaurus fischeri. The anatomy shows us that it is closely related to Dinocephalosaurus.

“Trachelosaurus fischeri is the first fossil of this reptile group to be found outside of China. It is also the oldest long-necked marine reptile known to date,” says Dr. Stephan Spiekman, an expert on this group of animals at the State Museum of Natural History Stuttgart.

Researchers present the world's oldest long-necked marine reptile
Skeletal reconstruction of Trachelosaurus fischeri and comparison with other long-necked, aquatic tanysaurians. Credit: Swiss Journal of Palaeontology (2024). 

After the great mass extinction at the Permian-Triassic boundary 252 million years ago, there was a very rapid diversification of new  species on both land and in the water at the beginning of the Triassic period. These included the first long-necked marine reptiles. How these complex evolutionary biological developments took place is an important subject of research.

The scientists suspect that Trachelosaurus fischeri was washed into a shallow water area 247 million years ago, as footprints of land-dwelling animals are also preserved on the rock in which the fossil is preserved.

For the researchers, the find and its re-evaluation are another step toward a better understanding of  at the beginning of the Triassic period. The history of the fossil shows the importance of historical  and university collections for natural history research, emphasize the authors of the study.

New discoveries from various parts of the world regularly enable scientists to reinterpret what was already discovered many years, sometimes even centuries, ago and carefully being kept in museums.

Fixing space-physics mistake enhances satellite safety
The Van Allen radiation belts provide a natural analog to artificial radiation belts that could occur after a high-altitude nuclear explosion. In this image, the red lines circling Earth is an artificial belt of high intensity, and the yellow regions are the natural belts; LEO/MEO/GEO refer to low-Earth orbit, medium Earth orbit and geostationary Earth orbit. Credit: Los Alamos National Laboratory

Correcting 50-year-old errors in the math used to understand how electromagnetic waves scatter electrons trapped in Earth’s magnetic fields will lead to better protection for technology in space.

“The discovery of these errors will help scientists improve their models of artificial radiation belts produced by high-altitude  and how an event like that would impact our space technology,” said Greg Cunningham, a space scientist at Los Alamos National Laboratory. “This allows us to make better predictions of what that threat could be and the efficacy of radiation belt remediation strategies.”

Heliophysics models are important tools researchers use to understand phenomena around the Earth, such as how electrons can become trapped in the near-Earth space environment and damage electronics on space assets, or how Earth’s magnetic field shields us from both  and particles in solar wind.

Cunningham is particularly interested in studying the Van Allen radiation belts because they provide a natural analog to artificial radiation belts that could occur after a high-altitude nuclear explosion.

“In an artificial radiation belt, electrons produced by a nuclear explosion can become trapped in the Earth’s magnetic field in the same way as naturally occurring radiation belts,” Cunningham said. “When these electrons become trapped in the inner radiation belt for many years, they could destroy existing satellites and make it impossible to deploy new ones.”

Researchers in the heliophysics community have long been using quasilinear theory, which explains plasma turbulence, to understand particle scattering. Simulation models based on the theory play an important role in understanding how to protect .

But through his research, Cunningham tried to rederive papers based on quasilinear theory and discovered errors in the longstanding equation used across the space-physics community.

“In certain types of models, this error can really impact the answer you get; you can get orders of magnitude difference in the scattering rates,” Cunningham said. “Now, researchers who have written papers over the last 20 or 30 years can go back and take a look and see whether or not this affects their work.”

“The error went undiscovered for so long simply because the research community didn’t think the original authors, who are highly cited researchers in the field, could have made this mistake,” he added.

Cunningham’s paper detailing the errors was recently published in Journal of Geophysical Research: Space Physics.

Shark-bitten orcas in the Northeastern Pacific could be a new population of killer whale
An infographic showing the differences between the three orca ecotypes that live along the coasts of California and Oregon and the potential unique population. Credit: UBC

UBC researchers believe a group of killer whales observed hunting marine mammals including sperm whales, as well as a sea turtle, in the open ocean off California and Oregon could be a new population.

Based on available evidence, the researchers posit in a new study published in Aquatic Mammals that the 49 orcas could belong to a subpopulation of transient killer whales or a unique oceanic population found in waters off the coast of California and Oregon.

“The open ocean is the largest habitat on our planet, and observations of killer whales in the high seas are rare,” said first author Josh McInnes, a master’s student at the UBC Institute for the Oceans and Fisheries (IOF). “In this case, we’re beginning to get a sense of killer whale movements in the open ocean and how their ecology and behavior differs from populations inhabiting coastal areas.”

Three ecotypes of killer whales live along the coasts of California and Oregon: ‘residents,’ ‘transients,’ and ‘offshores’.

The unknown orcas have been spotted before, but the new paper contains a weight of evidence gathered from nine encounters with 49 animals from 1997 to 2021, enough to form a solid hypothesis, the researchers said.

“It’s pretty unique to find a new population. It takes a long time to gather photos and observations to recognize that there’s something different about these killer whales,” said co-author Dr. Andrew Trites, IOF professor.

The 49 killer whales could not be matched with any known animals through photos or descriptions. “In one of the first encounters researchers had with a pod of these oceanic killer whales, they were observed taking on a herd of nine adult female , eventually making off with one. It is the first time killer whales have been reported to attack sperm whales on the West Coast,” said McInnes.

“Other encounters include an attack on a pygmy sperm whale, predation on a northern elephant seal and Risso’s dolphin, and what appeared to be a post-meal lull after scavenging a leatherback turtle.”

Shark scars provide vital clues

A key clue to the new population’s presumed habitat range lies in cookie-cutter shark bite scars observed on almost all of the orcas. This parasitic shark lives in the open ocean, meaning the new population primarily inhabits deep waters far from land.

The orcas also feature physical differences from the three main ecotypes, including in their  and saddle patches—the gray or white patches by the fin.

“While the sizes and shapes of the dorsal fins and saddle patches are similar to transient and offshore ecotypes, the shape of their fins varied, from pointed-like transients to rounded-like offshore killer whales,” said McInnes. “Their saddle patch patterns also differed, with some having large uniformly gray saddle patches and others having smooth narrow saddle patches similar to those seen in killer whales in tropical regions.”

Along with marine mammal stock assessment surveys, fishermen and passengers on an open-ocean birding expedition and whale-watching tour also provided observations of the unidentified killer whales, said Dr. Trites. Spotting the new  has become something of a hobby among fishermen, some of whom have bought cameras for their trips specifically to snap an encounter, the researchers said.

The researchers hope to document more sightings and gather more information, including acoustic data about the orcas’ calls and  from DNA samples to investigate further how these  may differ, or not, from already documented populations.

Seismological study shows ancient lower mantle flow field under Philippine sea plate
A schematic diagram showing remnants of the early Cenozoic Pacific lower mantle flow beneath the Philippine Sea Plate. The white bars and gray dashed lines denote remnants of the Pacific lower mantle flow field at about 50 Ma and 40 Ma, respectively. Credit: IOCAS

Researchers from China and Japan have discovered distinct characteristics of Earth’s lower mantle flow field. They investigated seismic anisotropy in the upper part of the lower mantle beneath the Philippine Sea Plate (PSP) and found that the ancient lower mantle flow field is still preserved there.

The  is an important layer of the Earth and may play an important role in the evolution and material cycling of Earth’s interior. It is generally believed to be not only the final destination of subducted slabs, but also the birthplace of mantle plumes, which are two major styles in the evolution and material cycling of the Earth’s surface and interior. However, our knowledge of the characteristics of the flow field and geodynamics of the lower mantle is still deficient.

In this study, the researchers performed P-wave azimuthal anisotropy tomography to image the 3D anisotropic structure of the crust and mantle down to a depth of 1,600 km beneath the PSP. The tomographic results show that N-S fast  directions (FVDs) exist at depths of 700–900 km below the mid-PSP. They also observed two isolated fast velocity anomalies with NW-SE FVDs at depths of 700–1,600 km beneath the PSP.

They found that the N-S FVDs at depths of 700–900 km are not related to the slab subduction, because they occur away from the present subduction zones. They are also independent of a , as there has been no active mantle plume beneath the PSP since the early Cenozoic.

Seismological study shows ancient lower mantle flow field under Philippine sea plate
Map views of P-wave azimuthal anisotropic velocity tomography. The orientation and length of the black bars represent the fast velocity direction and amplitude of azimuthal anisotropy, respectively. Credit: IOCAS

Based on previous geodynamic simulations and seismological results, the researchers inferred that the N-S FVDs at depths of 700–900 km reflect the remnant Pacific lower mantle flow field at about 50 Ma.

In addition, the two isolated fast velocity anomalies are consistent with seismic scatterers at depths of 1,000–1,800 km detected by previous seismological studies, and their locations are generally consistent with that of the spreading center between the Izanagi and Pacific plates when this spreading center was about to subduct beneath the Eurasian Plate. Thus, the isolated fast velocity anomalies are inferred to be remnants of the subducted Izanagi slab.

“The NW-SE FVDs in the two isolated fast anomalies are further inferred to reflect the Pacific lower mantle flow field at about 40 Ma, because the two isolated fast velocity anomalies are surrounded by amorphous mantle flow field and are not affected by the present lower mantle flow,” said Prof. Fan Jianke from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS), first and corresponding author of the study.

“Our study shows that seismic anisotropy is more widespread in the lower mantle than previously thought,” said Prof. Fan. “These observations also provide important and independent seismic evidence for the existence of past deformation in the lower mantle, which can help us better understand the geodynamic properties of the lower mantle.”