Showing posts with label Australia. Show all posts
Showing posts with label Australia. Show all posts

Wednesday, January 15, 2020

The Australian firestorms: portents of a planetary future

by Andrew Glikson
Earth and climate scientist
Australian National University

Global warming and its disastrous consequences are now truly with us since the second part of 2019. At the moment a change in the weather has given parts of the country a respite from the raging fires, some of which are still burning or smoldering, waiting for another warm spell to flare up. The danger zones include the Australian Capital Territory, from where these lines are written. To date, 18.6 million hectares (186,000 square kilometers) were burnt, including native forests, native animals, homesteads and towns, and 24 people died. The firestorms betray harbingers of a planetary future, or a lack of such, under ever rising temperatures and extreme weather events inherent in fossil fuel driven global warming.

Global heating

As the atmospheric concentration of the well-mixed greenhouse gases rise (CO₂ >411.76 ppm; CH₄ >1870.5 ppb; N₂O >333 ppb plus trace greenhouse gases) land temperatures soar (NASA global sea-land mean of 1.05°C since 1880). According to Berkeley Earth global land temperatures have increased by 1.5C over the past 250 years and mean Arctic temperatures have risen by 2.5°C to 3.0°C between 1900 and 2017. According to NASA :
  1. “Extreme heatwaves will become widespread at 1.5 degrees Celsius warming. Most land regions will see more hot days, especially in the tropics.
  2. At 1.5°C about 14 percent of Earth’s population will be exposed to severe heatwaves at least once every five years, while at 2 degrees Celsius warming that number jumps to 37 percent.”
  3. “Risks from forest fires, extreme weather events and invasive species are higher at 2 degrees warming than at 1.5 degrees warming.”
  4. “Ocean warming, acidification and more intense storms will cause coral reefs to decline by 70 to 90 percent at 1.5 degrees Celsius warming, becoming all but non-existent at 2 degrees warming.”
Figure 1. The distribution of global fires. NASA.

However, bar the transient masking effects of sulphur aerosols, which according to estimates by Hansen et al. (2011) induce more than 1.0°C of cooling, global temperatures have already reached near 2.0°C (by analogy to the requirement for a patient’s body temperature to be measured before and not after aspirin has been taken). As aerosols are not homogeneously distributed, in some parts of the world temperatures have already soared to such levels. Thus the degree to which aerosols cool the earth, which depends on aerosol particle size range, has been grossly underestimated.

The rate of global warming, at ~2 to 3 ppm year and ~1.5°C in about one century, faster by an order of magnitude then geological climate catastrophe such as the PETM and the KT impact, has taken scientists by surprise, requiring a change from the term climate change to climate calamity.

The Australian firestorms

In Australia mean temperatures have risen by 1.5°C between 1910 and 2019 (Figure 2), as a combination of global warming and the ENSO conditions, as reported by the Bureau of Meteorology.

“The Indian Ocean Dipole (IOD) has returned to neutral after one of the strongest positive IOD events to impact Australia in recent history ... the IOD’s legacy of widespread warm and dry conditions during the second half of 2019 primed the Australian landscape for bushfire weather and heatwaves this summer. In the Pacific Ocean, although indicators of the El Niño–Southern Oscillation (ENSO) are neutral, the tropical ocean near and to the west of the Date Line remains warmer than average, potentially drawing some moisture away from Australia.”

Figure 2. (A) Australian mean temperature. (B) Severe fire weather. (C) Drought. (D) Driest year.
Bureau of Meteorology
The prolonged drought (Figure 2 C, D), low fuel moisture, high temperatures (Figure 2A) and warm winds emanating from the inland have rendered large parts of the Australian continent tinder dry, creating severe fire weather (Figure 2B) subject to ignition by lightning and human factors. Fires on a large scale create their own weather (see: bushfire raging in Mount Adrah and firestorm). Observations of major conflagrations, including the 2003 Canberra fires, indicate fires can form atmospheric plumes which can migrate and as hot plumes radiating toward the ground (fire tornadoes).

The underlying factor for rising temperatures and increasingly severe droughts in Australia is the polar-ward shift in climate zones (see map Oceania) as the Earth warms, estimated as approximately 56-111 km per decade, where dry hot subtropical zones encroach into temperate zones, as is also the case in South Africa and the Sahara.

Smoke signals emanating from the Australian fires are now circling around the globe (Figure 3) signaling a warning of the future state of Earth should Homo sapiens, so called, not wake up to the consequences of its actions.

Figure 3. (A) Smoke emanating from the southeastern Australian fires (January 4, 2020);
(B) smoke from the pyro-cumulonimbus clouds of the Australian fires drifting across the Pacific Ocean.
The fire clouds have lofted smoke to unusual heights in the atmosphere. The CALIPSO satellite observed smoke soaring between 15 to 19 kilometers on January 6, 2020—high enough to reach the stratosphere. NASA.

Andrew Glikson
Dr Andrew Glikson
Earth and climate scientist
Australian National University

Thursday, November 14, 2019

Portents of continental-scale fires as the Earth warms

Andrew Glikson
Earth and climate scientist
Australian National University

The effects of encroaching deserts and of fire storms on terrestrial forests originally developed under moderate conditions distinct from those emerging under rapid global warming and extreme weather events may have been underestimated. Average global temperatures do not tell the story — it is the increasingly frequent weather anomalies which do. Powerful psychological factors prevent many scientists from expressing their worst fears, a phenomenon dubbed as “scientific reticence”.

As the tropical climate zones expand toward the poles, moderate climate zones shift polar-ward and are contracting where they clash with polar-derived cold air and ice melt water flow through weakened jet stream boundaries. As climate zones are shifting at a rate of 56-111 km per decade and ecosystems have only a short time to adapt, arid zones expand and droughts and fires consume the moderate-climate forests and formerly fertile habitats. Allen et al. (2012) suggest the increase in black carbon aerosols and tropospheric ozone constitute significant factors generating a polar-ward shift of moderate climate zones.

Global fire maps by NASA document the progression of wildfires since about 2000, including major fires in Siberia, northwest Europe, southern Europe, Russia, Southeast Asia, Australia, central and southern America, California and elsewhere (Fig. 1).

Figure 1. The Moderate Resolution Imaging Spectro-radiometer (MODIS) on NASA's Terra satellite showing fires around the world. Credit: NASA
Some of the global patterns that appear in the fire maps are the result of natural cycles of rainfall, dryness, and lightning. For example, naturally-occurring fires are common in the boreal forests of Canada in the summer. In other parts of the world, the patterns are the result of human activity. For example, the intense burning in the heart of South America from August-October is a result of human-triggered fires, both intentional and accidental.

Many scientists and the IPCC have underestimated the scale and rate of global warming and its consequences. With exceptions, the need for excessive caution and absolute certainty in science is often manifested in reticence from the mainstream science (‘Down to Earth’ 2019). However, the available evidence suggests that scientists have in fact been conservative in their projections of the impacts of climate change and at least some of the key attributes of global warming from increased atmospheric greenhouse gases have been underpredicted, particularly in IPCC assessments of the physical science by Working Group I.

By contrast, at a speed hardly anticipated about 20 years ago, wildfires have been spreading around the globe over large parts of the continents.

Nor do average global land-ocean temperatures tell the whole story. It is the increasingly frequent anomalies which underlie extreme weather events (Fig. 2), including rapid Arctic melt, heatwaves, fires, storms and cyclones, which underpin the fundamental shift in the state of the terrestrial climate.

Figure 2. Temperature anomaly distribution: The frequency of occurrence (vertical axis) of local temperature anomalies (relative to 1951-1980 mean) in units of local standard deviation (horizontal axis). Area under each curve is unity. Image credit: NASA/GISS.
It has been stated “What happens in the Arctic doesn't stay in the Arctic”. Temperatures in the Arctic have reached 34°C in July 2019, affecting melting over 700,000 km² in Greenland late May 2019. The weakening of the circum-Arctic jet stream ensues in its undulation and intersection by warm air masses moving north and by cold air masses moving south, along with ice melt from the Greenland ice sheet forming cold regions in the North Atlantic Ocean.

Figure 3. Weather systems driven by the 
strong westerly winds of the Antarctic 
polar vortex curl over the southern 
continents (NASA, Galileo).
According to the Australian Climate Council, climate change has contributed to a southward shift in weather systems that typically bring cool season rainfall to southern Australia. As the cold humid spirals of the Antarctic vortex (Fig. 3) recede to the south, since the 1970s late autumn and early winter rainfall has decreased by 15% in southeast Australia, and Western Australia’s southwest region. Current drought conditions come after a 2016/2017 and 2018 Summer characterized by record-breaking temperatures, followed by a record dry winter. Rainfall over southern Australia during autumn 2018 was the second lowest on record (Fig. 4). The drought has reached extreme level, accompanied by wildfires. Australia, like other parts of the world, is paying the price of climate change in terms of growing damage to its agriculture, communities and way of life.

Figure 4. Australia: Current effects of global warming. 
A. 2018 annual mean temperatures compared to historical temperature observations. 
B. 2018 annual rainfall compared to historical rainfall observations.
The global rise rate in CO₂ has reached 2 to 3 ppm/year, the fastest rate since 66 million years ago, and a level of CO₂-equivalent (a value including the radiative forcing of methane and nitrous oxide) near 500 ppm. According to the IMF (2017), the world is subsidizing fossil fuels by $5.2 trillion, equal to roughly 6.5% of global GDP. By contrast, the loss of wealth due to reduced agricultural productivity due to climate change is projected to exceed $19 billion by 2030, $211 billion by 2050 and a projected $4 trillion by 2100.

Figure 5. Fires in Australia, November 8, 2019, NASA Worldview 
As stated by Hansen et al. (2012): “Burning all fossil fuels would create a different planet than the one that humanity knows. The palaeoclimate record and ongoing climate change make it clear that the climate system would be pushed beyond tipping points, setting in motion irreversible changes, including ice sheet disintegration with a continually adjusting shoreline, extermination of a substantial fraction of species on the planet, and increasingly devastating regional climate extremes”.

Andrew Glikson
Dr Andrew Glikson
Earth and climate scientist
Australian National University

The Archaean: Geological and Geochemical Windows into the Early Earth
The Asteroid Impact Connection of Planetary Evolution
The Plutocene: Blueprints for a Post-Anthropocene Greenhouse Earth
Evolution of the Atmosphere, Fire and the Anthropocene Climate Event Horizon
Asteroids Impacts, Crustal Evolution and Related Mineral Systems with Special Reference to Australia
Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene
From Stars to Brains: Milestones in the Planetary Evolution of Life and Intelligence