Category Archives: Climate Change; a Geological Perspective

Class 5; The Toba eruption – how a super volcano almost stopped humanity in its tracks

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Toba Lake, in northern Sumatra, occupies the ancient Toba caldera. One of its outlets, the Asahan River, is the site of some spectacular white-water, a kayaker’s delight. For anyone willing to run the river, spare a thought for your early human ancestors, who it seems, were lucky to survive the aftermath of a cataclysmic super volcanic eruption 74,000 years ago. Be thankful that they did. Continue reading

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The intriguing paradox of global warming piggybacking on global cooling

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Flood, fire, drought … We have, by luck and muddled management, thwarted pestilence, but it seems that changing weather patterns everywhere are leading us on a merry dance.  Our climate is giving us a bumpy ride; anyone living in the Caribbean and southeast US, or Bangladesh, will attest to this, given the havoc that hurricanes and tropical cyclones have wrought over the past few months (northern hemisphere summer, 2017).  The skinny, outer layers of our world (air and oceans) seem to be getting warmer. No doubt there are consequences?

It may seem paradoxical, but global warming is taking place against a backdrop of global cooling. Forcing of global climates is governed by internal (within our own skinny sphere) and external agents; the latter by solar output and earth’s changing orbit. There is now, good Continue reading

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A greener earth; Earth’s vegetation is responding to increasing atmospheric CO2

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Photosynthesis, a process that had its beginnings about 2.5 billion years ago, has an awesome responsibility; it keeps us breathing. It is a metabolic process in plants that uses the energy from sunlight to drive chemical reactions; reactions that produce amino acids, proteins, sugars and other compounds that create the architecture of plants.  The process takes atmospheric CO2, converts the carbon plus other nutrients to organic compounds, then expels the left-over oxygen. Plants help regulate the composition of the atmosphere – they are our other set of lungs.

It has been shown experimentally that photosynthesis increases in many kinds of plants (some more than others), as the supply of atmospheric CO2 also increases. On a global scale, this is referred to as greening of the earth, where both regional studies, and more recently satellite data show an overall increase in plant growth, and an increase in growing seasons. In Europe and North America, the seasonal leaf-out (or bud-break) for the period 1950 to the 1990s was 2-4 weeks earlier than pre-1950. Continue reading

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Which satellite is that? What does it measure?

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Space may well be the final frontier (there are one or two on earth that still require some work), but the space around our own planet is decidedly crowded. Folk at NASA’s Goddard Space Center (Maryland) estimate about 2300 satellites now orbit Earth; vehicles in various states of repair, use or disuse, of which a little more than 1400 are operational Continue reading

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So, adding CO2 does increase surface heating; how science has filled another gap in our knowledge

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Read any scientific paper or blog on climate and you’re bound to come across the phrase radiative forcing.  Radiative forcing is central to all climate science. Radiation from the sun heats our atmosphere and earth surface.  Some of this radiation is reflected back to space. If there is a balance between incoming and outgoing radiation then average global atmospheric temperatures neither increase or decrease. However, if the balance is perturbed, climate will warm or cool. Radiative forcing causes climate imbalances.  Thus, volcanic aerosols tend to cool things off, decreasing albedo will tend to warm them. Continue reading

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Volcanism does not cause glaciations; let’s turn this statement on its head

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It is almost a truism that volcanic eruptions influence climate. Cold winters and even failed crops, particularly in the northern hemisphere, followed on the heels the Tambora, Krakatoa, and Pinatubo eruptions.  But these climate aberrations were relatively short-lived, counted in years; the stratospheric aerosols and fine volcanic ash that reflect solar radiation back into space, eventually succumb to gravity and fall to earth.  Eruptions of this kind do not result in long-lived, or permanent changes; they are temporary blips on an evolving earth and an evolving climate. Continue reading

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A burp and a hiccup; the volcanic contribution of carbon dioxide to the atmosphere

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Of the two certainties in life, volcanoes offer the most excitement (death and taxes are basically the same thing).  They are magnificent while asleep; a primeval ruggedness that stirs the imagination. We paint them, we eulogise them. And when they awaken, we run for cover. Whether in a state of dormancy or high agitation, they leave an impression on our inner and outer landscapes.

All active volcanoes emit gas; pre-, during and post-eruption. On average, 96% of volcanic gases are water vapour, the remaining components being CO2, SO2 (most common), plus a little helium, nitrogen, carbon monoxide, hydrogen sulphide, and a few halides. Volcano-derived carbon dioxide is frequently cited as a culprit for increasing atmospheric CO2 concentrations in Continue reading

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