|2011-05-25 12:31:55||Be warned or be Warmed|
BE WARNED OR BE WARMED!
How should we respond to a political party which supports its leaders view that climate change is real but has little to do with CO2 and even less to do with human activities? Leaders who believes that safeguarding the short term profits of business and its ability to compete in the international market place is far more important than the disastrous effects on-going global warming will have on climate and the environment? A leader who refuses to believe the science, the advice of climate scientists, National Science Academies and Universities or the frightening prognoses of some of their most prominent and respected members.
Such irresponsible doubt and denial demands a statement of exactly what the dire warnings of climate scientists are, the basis on which they are made and the effects on our habitat.
Fundamental to everything that follows is the rise in temperatures of the Earths oceans, atmosphere and land. We know temperatures are rising because they are measured by land based instruments and by satellites. We know from those measurements that the rate at which temperature is rising is accelerating. Even some leading “skeptics” accept this. What most dispute is the cause of that increase.
What “skeptics” assert, without producing a shred of compelling supportive evidence, is that rising global temperature is caused by changes in cloud cover, solar activity cosmic rays, inaccurate data and a range of other reasons. Scientists have shown that none of these are causative and that supportive arguments put forward by their proponents are based on misrepresentation or distortion of accepted science or use of data which supports an argument while ignoring that which does not – in short, by lying.
On the basis of these lies, political leaders and “skeptical” media outlets claim that global warming is not caused by CO2 releases and that human activity has insignificant effect. They say curbing greenhouse gas emissions will achieve nothing and if pursued would make small ineffectual reduction of carbon in the atmosphere.
We know from historical evidence (content of ice and sediment cores) that global warming in the past has been cyclical and the result of increase in the level of solar radiation reaching the Earth. That increase was produced by a combination of greater solar activity and changes of the orbital parameters of the Earth - eccentricity, obliquity and precession of axis. The result was gradual reduction of albedo caused by melting of land based snow and ice cover producing sufficient warming to release vast quantities of cryogenically stored methane. The effect: relatively sudden warming by 8°C-10°C above ice age temperatures.
These warm periods lasted ~10,000 years before on-set of gradual temperature decline caused by return to orbital parameters reducing exposure to solar radiation, slow weathering of rock and ocean cooling enabling absorption of carbon from the atmosphere. This was accompanied by expansion of the area covered by snow and ice, gradually increasing albido and energy radiated back into space.
The Vostok Ice Core shows this cycle of global warming is repeating itself for the 5th time in the past 450,000 years and many “skeptics” assert that this is again due to the “Natural” cycle described above. However, there is no evidence to support this claim. Both solar activity and Earths orbital parameters are consistent with declining exposure to solar radiation, particularly at the poles – facts confirmed by satellite and surface measurements – and consistent with declining temperature after reaching a cyclic maxima.
Yet what we see is temperature continuing to increase and doing so at a rate much faster than previously known. Preceding and accompanying this increase is rising concentration of greenhouse gases in the atmosphere, particularly CO2. We have known for over a century that CO2 absorbs energy in the infra-red spectrum radiated from the Earths surface and emits much of it back towards the surface, increasing surface and atmospheric temperatures.
This process and relatively rapid increase in CO2 has now amplified global temperatures to the point where, in the absence of natural forcings, they have initiated thawing of polar ice triggering release of methane which has accumulated in permafrost and clathrate over millennia. The result is that offshore release of methane is now ~8 million tones/annum and onshore ~4 million tones/annum. Growth in the volume of these releases is inevitable and can no longer be controlled by human action.
Because these releases are from shallow depth, they have not oxidized to CO2 and are entering the atmosphere as CH4 which will oxidize to CO2 over a 10-20 year period. On this time scale CH4 has a global warming potential of ~75, so it has a radiative capacity ~75 times greater than CO2. Therefore present CH4 emissions equate to about 900 million tones/annum, contributing to polar amplification which will speed-up thawing of ice and accelerate release of CH4.
Scientists believe that this could result in release of 1.5 gigatonnes (Gt)/annum (~112 Gt CO2-e) by 2050 and 3.5 gigatonnes/annum (~262 Gt CO2-e) before 2100, largely in the form of CH4. Dr Shakhova warns that emissions of this magnitude are sufficient to cause abrupt climate change. The likely impact is that Arctic temperatures could rise by up to 9°C and globally by ~3°C or more. The effects of this are as follows:
Melting of ice
The speed with which sea ice melts would accelerate with the likelihood that by 2030 the Arctic Ocean could be ice-free in summer and remain so for extended periods thereafter. Likewise land-based ice and snow cover would also melt faster, exposing land so solar radiation for longer periods each year, further amplifying Arctic temperature.
Hansen et al (2011) predicts that this would cause decadal doubling of the rate of ice loss from the Greenland Ice Sheet, accelerating that loss from ~250 Gt/annum in 2010 to ~65,000 Gt/annum by 2100. Rising sea temperature would also increase the rate of ice loss from the West Antarctic Ice Sheet, most of which rests on the seabed and is very vulnerable to warming ocean currents.
Rising sea level
Many climate scientists, including members of the Australian Climate Commission, are of the view that sea level rise by 2100 will be <2m but this does not appear to be related to factors discussed above. Taking those factors into account, it is estimated that the combined effect of rising global temperature, polar amplification and ice sheet mass loss could result in a non-linear increase in sea level of 5m by 2100.
Hansen et al 2011 predict sea level rise of only 0.5m by 2080 due to relatively slow loss of mass from ice sheets but thereafter very rapid rise of a further 4.5m by 2095. If the magnitude of CH4 releases are as predicted by Shakhova et al (2010), it is possible that loss of ice and sea level rise could be ~1m by 2050. Either way we are faced with a 5m sea level rise before 2100, largely governed by the rate of polar ice loss. The effects of such a rapid rise in sea level will include the following:
The fact that prior to 2050 polar ice loss and sea level rise are expected to be relatively slow induces a false sense of security among political leaders and “skeptics”. Even when forewarned, humans can offer little defence against the effects of a 5m sea level rise, other than to avoid it. Although immediate reduction of greenhouse gas emissions can slow acceleration of rising sea level, ultimately its full effects will be felt on every coast, wreak havoc and continue well beyond 2100.
Climate events severity
For 20 years climate scientists have warned that rising sea level and atmospheric temperature, will increase both the frequency and severity of climate events. Their advice has largely been ignored despite growing evidence in the 21st century confirming its veracity. As recently as May 2011, the IPCC Chairman, Dr Pachauri, warned that we now have little alternative but to get used to living with an increasingly severe climate.
Climate events include extremes of temperature, wind and precipitation or lack of it. These manifest themselves in the form of prolonged periods of cold weather and heat waves, cyclones, tornadoes, and other damaging high wind events, persistent drought conditions or periods of very heavy rainfall or high humidity. These events have one thing in common. They can and do destroy or cause damage to human habitat, kill its inhabitants or force them to flee.
Homo sapiens and many other animal species can and do defend themselves against periods of extreme cold and are better able to do so than withstand heat. Heatwaves, where temperatures exceed 35°C for prolonged periods are life-threatening, particularly for older people. Sherwood et al (2010) warn that the real danger comes when this heat is accompanied by high humidity. It then kills everyone, not just the aged.
When preceded by periods of low rainfall which kills or dries-out vegetation, heatwaves cause bushfires, often difficult or impossible to control. These destroy or damage dwellings, buildings and other assets including those of economic importance such as food crops and can destroy infrastructure such as electricity cables, bridges and control facilities.
Humans have shown they have limited ability to adapt to conditions of drought and low rainfall provided it is not too persistent. Underground water storage and distribution channels constructed by the ancient Medes and Persians and still in use to-day are evidence of this. However drought lasting a decade or more has destroyed civilizations such as that of the Classic Maya, despite their efforts at water conservation.
Sudden deluge causing widespread flooding is often more problematic because it destroys crops, can prevent new planting and depletes land fertility. It also destroys buildings and infrastructure needed to process and transport food to markets. It often damages sewage processing facilities, contaminate fresh water sources and spread diseases which may kill humans.
High velocity wind events are in some ways less problematic, despite being extremely violent and very destructive. Buildings and infrastructure can be designed to withstand their ferocity however this is uncommon and consequently their impact is often great, particularly when they strike major population centres such as Darwin. High wind events also produce storm surges increasing the energy content of waves which erode the coastline, inundate river deltas and produce local flooding.
Myopia engendered by the prospect of short-term political or financial gain has discouraged or prevented timely reduction of greenhouse gas emissions which would have avoided dangerous global warming. By embarking on that measure now it may still be possible to delay and reduce, though not escape the severity of its effects.
We leave our grandchildren a rapidly changing environment where a burgeoning population of over 10 billion will be confronted with damaged, shrinking habitat endowed with increasingly scarce food and water to sustain them.
Those endowed with the spark of genius unique to our species may yet develop and apply technology to remove sufficient carbon from the atmosphere to prevent further deterioration of the cryosphere. This alone can prevent global warming resulting in catastrophic climate change threatening our ability to survive on this planet.
The one thing our political leaders and businessmen can not claim is that they did not know the full import of what climate scientists have warned us. In their scaremongering opposition to essential remedial change they knowingly and willfully condemn us to an increasingly bleak and damaging future.