Europes Little Ice Age coincided with low solar activity.
Pieter Brueghels painting The Census at Bethlehem.
A solar slump may have chilled the Northern Hemisphere.
The flickering sun may cause rapid climate change, according to a new comparison of climate records. A 200-year cold snap 10, 300 years ago seems to have coincided with a passing slump in the sun’s activity1.
Svante Bjorck of Lund University in Sweden and colleagues looked at sediments in Lake Starvatn on the Faroe Islands and in the Norwegian Sea, the width of growth rings in ancient German pine trees, and ancient ice drilled from deep within the Greenland ice sheet.
Bjorck and colleagues propose that a weakening of solar activity may have caused this mini chill. It coincided, they find, with a large increase in the amount of beryllium-10 trapped in Greenland ice - evidence of a solar flicker.
This radioactive form of beryllium is produced when cosmic rays from space collide with nitrogen and oxygen atoms in the atmosphere. The magnetic field around the Earth protects the planet from cosmic rays. This field is stronger when the sun is more active - emitting more ultraviolet radiation and displaying more sunspots - so fewer cosmic rays can penetrate.
The proposed relationship between solar activity and climate change is controversial, partly because some have tried to pin modern-day global warming on it rather than on a human-induced greenhouse effect.
There is evidence, however, linking changes in solar activity to climate fluctuations in the more recent past. Abnormally high activity around AD 1100-1250, for example, has been mooted as the cause of a period of warming in medieval Europe. And the ’Little Ice Age’ between the sixteenth and eighteenth centuries coincided with a period of low solar activity.
The most pronounced climate swings, such as ice ages, happen slowly and last a long time - 100,000 years or so. Gradual, periodic changes in the shape of the Earth’s orbit around the sun are thought to trigger these larger-scale changes.
Evidence of shorter-term climate change has been observed before in ice-core records from Greenland and Antarctica. Apparently the global average temperature can switch between today’s mild climate and ice-age frigidity in just a few decades.
Sudden shifts are thought to be mostly due to ocean circulation. When ice sheets melt at the end of an ice age, the oceans get an injection of fresh water. By making seawater less salty and therefore less dense, this can suppress the conveyor-belt circulation that normally carries warm water from the tropics to the poles. Deprived of this source of heat, the high latitudes grow cold.
PHILIP BALL | © Nature News Service
In times of climate change: What a lake’s colour can tell about its condition
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Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
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Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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