“Let us discuss intelligently the best mechanisms we should undertake rather than believing that the temporary warming slowdown means we can go back to sleep.” – Elder
By Phil Elder
The Intergovernmental Panel on Climate Change (IPCC) has just issued its Fifth Assessment Report, a follow-up to its 2007 version on global warming.
It is both sobering and persuasive, and even stronger in stating that Earth’s climate is warming and that human activity is now the main driver.
According to the report’s summary, “most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. . . . Depending on the scenario, about 15 to 40 per cent of emitted CO2 will remain in the atmosphere longer than 1,000 years.”
In other words, things will get worse before they get better, so deniers can be expected to complain every decade that we should give up because nothing we did worked. But our descendants will simply have to soldier on if they are to solve the problem we have created.
Climate change deniers denying global warming
The usual sources are lining up to deny these claims. Some work in or are financed by the hydrocarbon energy industry, so their objections to the science are not surprising. Some deniers resist the analysis for ideological reasons – they believe in less government and more personal freedom and sometimes even that the market is the only credible decision-mechanism. Still others don’t want to accept human-induced (anthropogenic) global warming because responding to it may involve uncomfortable changes to the status quo.
When the denial industry claims the scientific community is split on this question, it’s not surprising that laypersons get confused. Yet there is a 97 per cent+/- consensus in the peer-reviewed scientific literature that anthropogenic climate change is real. (This figure is also challenged by climate sceptics.) And it’s not only the IPCC which warns us about anthropogenic climate change. The Environmental Protection Agency in the U. S. is on board too. And surely the precautionary principle dictates action even without 100 per cent certainty.
Let us acknowledge, however, that although the “greenhouse effect” accords with common sense, global climate is extremely complex. For example, even with the global warming, some parts of the globe will turn colder and trends need many years to allow conclusive certainty. Vigorous and informed scientific debate is healthy for those who want to better understand the global warming drivers and then to develop effective remedial measures.
It is also true that some people on both sides on the debate have exaggerated, which has increased public cynicism.
Naysayers tend to “cherry-pick” their data – for example, they seize on the fact that the warming trend has been cut in half in the past few years, even while greenhouse gas emissions continue. Therefore, they say, mainstream science is wrong.
Global warming scientific evidence
But let’s stay with this one for a minute. First, choosing an unusually warm year as the baseline to assess global warming distorts the evidence.
Given that climate change happens over generations, and that weather varies from year to year in a zigzag pattern, it’s no surprise that 15 years of relatively little rises in temperature should occur from an unusually high base line. Looking at greenhouse gas levels since 1900, the upward trend could not be clearer.
We must agree with the deniers that warming and cooling cycles occurred well before human activity could have had any discernible effect. Things like el Niño, la Nina, wobbles in the earth’s rotation and orbit, fluctuations in its magnetic field, or solar storms and cosmic rays have in the past influenced climate change.
Global warming – 3 observations
Let us note three things, however. First, the most powerful climate change cycles occurred slowly, perhaps over millennia, so many species were able to migrate fast enough to remain viable as temperature zones shifted. Today’s changes, however, are orders of magnitude faster, even considering the present slowdown of the warming.
Second, given these natural cycles, we are a couple of thousand years overdue for re-glaciation, yet temperatures have been moving in the opposite direction.
Third, radical physical changes on earth like the Ice Age and then de-glaciation resulted from comparatively small changes in temperature.
Climate experts acknowledge these natural cycles, but most believe that they have caused much less than half and more probably about 15 per cent of the present warming trend.
Explanations for pause in global warming
Are any explanations for this pause in warming since about the turn of the century consistent with global warming? Yes.
For one, oceans have absorbed more heat than expected, due to changes in wind and current patterns, and have thus reduced the impact on air temperatures. (This rise, by the way, threatens many ocean species and is ominous for coral reef ecosystems. Also, since much greenhouse gas is eventually sequestered in the oceans, their increased acidification will also be a major threat to marine life.)
Another factor reducing the warming impact of greenhouse gases is, counter-intuitively, the burning of huge amounts of coal, because it produces vast amounts of particulates which in the short term help shield the earth from solar radiation. Unfortunately, this apparently benign effect lasts only months or years, while the increased greenhouse gases from that combustion will remain in the atmosphere for centuries. So coal has to be phased out fast.
Also worthy of note is the cooling effect observed from 2008-11 because of volcanic eruptions and aerosols in the air and perhaps lower solar radiation at the present stage of the solar cycle.
I do not doubt the sincerity of many people who reject the scientific consensus, but urge undecided readers to check out the affiliations and academic qualifications of the few ostensible “experts” who debunk anthropogenic climate change.
True, climate change is extraordinarily complex and not all its mechanisms are entirely understood. But as a legally-trained layman, I have weighed the evidence (as I was taught to do) and conclude both that anthropogenic climate change is occurring and that it poses an existential threat to modern civilization.
I say this, not to induce panic or hopelessness, but to urge all interested citizens (is anyone dull enough to believe that such a threat should just be ignored?) to inform themselves and then insist that our political leaders respond with ingenuity and vigour.
As not all past efforts to respond have been effective or efficient, let us discuss intelligently the best mechanisms we should undertake rather than believing that the temporary warming slowdown means we can go back to sleep.
Already arctic temperatures have increased by double the global average and melting of land-based ice and of methane-rich tundra could bring about rapid (in climate terms, over a generation or two) and nasty results. As the IPCC summary says, it “is virtually certain that near-surface permafrost extent at high northern latitudes will be reduced as global mean surface temperature increases.”
And we have already seen forest fires in Russia which were attributed to methane released from melting permafrost.
Phil Elder is Emeritus Professor of Environmental and Planning Law with the Faculty of Environmental Design at the University of Calgary.
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