Objections and answers in the global warming debate.
Although cockfighting and ethics reform may grab headlines during this Legislature, global warming-or climate change-also is slated for debate and was top news this week. On Jan. 23, Gov. Bill Richardson, other Democrats and the National Environmental Trust pre-empted President George Bush's discussion of climate change in his state of the union address to present their own proposals on how the US can work to curb and reverse the effects of global warming.
New Mexico already has been leading the states in its reforms, and Richardson announced in his opening remarks to the Legislature that he would push for tougher carbon emission standards for new cars and trucks sold in the state and 100 percent
renewable energy for public buildings, among other initiatives.
Despite the growing consensus about the need for such measures, skeptics still walk among us. This week's story by Coby Beck, adapted from Grist's "How to Talk to a Skeptic About Global Warming," is designed to provide answers to some of the common-and not so common-objections raised about global warming. To read the series in its entirety, go to
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Objection: Despite what the computer models tell us, there is actually no evidence of significant global warming.
Answer:
Global warming is not an output of computer models; it is a conclusion based on observations of a great many global indicators. By far the most straightforward evidence is the actual surface temperature record. While there are places-in England, for example-that have records going back several centuries, the two major
global temperature analyses can only go back approximately 150 years due to their requirements for both quantity and distribution of temperature recording stations.
The NASA GISS (Goddard Institute for Space Studies) Surface Temperature Analysis and Climatic Research Unit are the two most reputable globally and
seasonally averaged temperature trend analyses. Both trends are definitely and significantly up. In addition to direct measurements of surface temperature, there are many other measurements and indicators that support the general direction and magnitude of the change the Earth is currently undergoing. Empirical observations of satellite data, radiosondes, borehole analysis, glacial melt observations, sea ice melt, sea level rise, proxy reconstructions and permafrost melt lead to the same unequivocal conclusion that the Earth is warming.
There is simply no room for doubt: The Earth is undergoing a rapid and large warming trend.
Objection: Even the scientists don't know that the climate is changing more than normal and if it's our fault or not. If you read what they write, it is full of "probably," "likely," "evidence of" and all kinds of qualifiers. If they don't know for sure, why should we worry yet?
Answer:
Probability is the language of science. There is no proof; there are no absolute certainties. Scientists are always aware that new data may overturn old theories and that human knowledge is constantly evolving. Consequently, it is viewed as unjustifiable hubris to ever claim one's findings as unassailable.
But in general, the older and more established a given theory becomes, the less and less likely it is that any new finding will drastically change things. Even the huge revolution in physics brought on by Einstein's theory of relatively did not render Newton's theories of classical mechanics useless. Classical mechanics is still used all the time; it is, quite simply, good enough for most purposes.
But how well established is the greenhouse effect?
Greenhouse effect theory is more than 100 years old. The first predictions of anthropogenic global warming came in 1896. Time has only strengthened and refined those groundbreaking conclusions. We now have decades of very detailed and sophisticated climate observations, and supercomputers are crunching numbers in one second it would have taken a million 19th century scientists years with a slide rule to match. Even so, you will never ever get a purely scientific source saying "the future is certain."
But what certainty there is about the basic issue is close enough to 100 percent that for all practical purposes it should be taken as 100 percent. Don't wait any longer for scientific certainty; we
are there. Every major institute that deals with climate-related science is saying global warming is here and real and dangerous, even though they will not remove the "very likely" and "strongly indicated" qualifiers. The translation of what science is saying into the language of the public is this: Global warming is definitely happening and it is definitely because of human activities and it will definitely continue as long as CO2 keeps rising in the atmosphere.
The rest of the issue-how high will the temperature go, how fast will it get there and how bad will this be-is much less certain. But no rational human being rushes headlong into an unknown when there is even a 10 percent chance of death or serious injury. Why should we demand 100 percent certainty before avoiding this danger? Science has given the human race a dire warning with all the urgency and certainty we should need to prompt action.
Objection: Climate has always changed. Why are we worried now and why does it have to be humans' fault?
Answer:
Yes, climate has varied in the past, for many different reasons, some better understood than others. Present-day climate change is well understood, and different. Noting that something happened before without humans does not demonstrate that humans are not causing it today.
For example, we see in ice core records from Antarctica and Greenland that the world cycled in and out of glacial periods over 120 kiloyears (a kiloyear is a unit of 1,000 years). That climate cycle's timing is fairly well understood to be caused by changes in the orbit of the earth, though the mechanism behind the response has not been conclusively established. These orbital cycles are regular and predictable, and they are definitely not the cause of today's warming. The other important difference between the glacial-interglacial cycles and today is the rapidity of the current change. The rate of warming is on the order of 10 times faster today than in the ice cores.
Such rapid warming on a global scale is quite rare in the geological record, and while it may not be entirely unprecedented, there is strong evidence that whenever such a change has happened, whatever the cause, it was a catastrophic event for the biosphere.
Objection: The Antarctic ice sheets are actually growing, which wouldn't be happening if global warming were real.
Answer:
There are two distinct problems with this argument. First, any argument that tries to use a regional phenomenon to disprove a global trend is dead in the water. Anthropogenic global warming theory does not predict uniform warming throughout the globe. We
need to assess the balance of the evidence.
In the case of this particular region, there is actually very little data about the changes in the ice sheets. The growth in the East Antarctic ice sheet indicated by some evidence is so small, and the evidence itself so uncertain, the sheet may well be shrinking.
But even this weak piece of evidence may no longer be current. Some recent results from NASA's GRACE (Gravity Recovery and Climate Experiment), measuring the gravitational pull of the massive Antarctic ice sheets, have indicated that on the whole, ice mass is being lost.
Second, ice sheet thickening is not inconsistent with warming! Warmer climates tend toward more precipitation. The Antarctic is one of the most extreme deserts on the planet.
As it warms, we would expect it to receive more snow. But even a whopping warming of 20 degrees-say, from -50 degrees C to -30 degrees C-would still leave it below freezing, so the snow wouldn't melt. Thus, an increase in ice mass.
While on the subject of ice sheets: Greenland is also growing ice in the center, for the same reasons described above. But it is melting on the exterior regions, on the whole losing approximately 200 km3 of ice annually, doubled from just a decade ago. This is a huge amount compared to changes in the Antarctic-approximately three orders of magnitude larger. So in terms of sea-level rise, any potential mitigation due to East Antarctic ice sheet growth is wiped out many times over by Greenland's melting.
Objection: Global warming is a hoax perpetrated by environmental extremists and liberals who want an excuse for more big government (and/or world government via the UN).
Answer:
This is a common line, regardless of how ridiculous it is, so it should not go unanswered. Here is a list of organizations that accept anthropogenic global warming as real and scientifically well-supported:
NASA's Goddard Institute of Space Studies; National Oceanic and Atmospheric Administration; Intergovernmental Panel on Climate Change; National Academy of Sciences; State of the Canadian Cryosphere; Environmental Protection Agency; the Royal Society of the UK; American Geophysical Union; American Meteorological Society; American Institute of Physics; National Center for Atmospheric Research; American Meteorological Society; and Canadian Meteorological and Oceanographic Society.
Every major scientific institution dealing with climate, ocean and/or atmosphere agrees that the climate is warming rapidly and the primary cause is human CO2 emissions. In addition to that list, a joint statement that specifically and unequivocally endorses the work and conclusions of the Intergovernmental Panel on Climate Change (the IPCC Third Assessment report) was issued by:
Academia Brasiliera de Ciencias (Brazil); Royal Society of Canada; Chinese Academy of Sciences; Academie des Sciences (France); Deutsche Akademie der Naturforscher Leopoldina (Germany); Indian National Science Academy; Accademia dei Lincei (Italy); Science Council of Japan; Russian Academy of Sciences; Royal Society (United Kingdom); and National Academy of Sciences (US).
But if scientists are too liberal and politicians too unreliable, perhaps some will find the opinion of key industry representatives
more convincing:
BP, the largest oil company in the UK and one of the largest in the world, has stated: "There is an increasing consensus that climate change is linked to the consumption of carbon based fuels
and that action is required now to avoid further increases in carbon emissions as the global demand for energy increases."
Shell Oil has stated: "Shell shares the widespread concern that the emission of greenhouse gases from human activities is leading to changes in the global climate."
Eighteen CEOs of Canada's largest corporations, in an open letter to the prime minister of Canada, stated: "Our organizations accept that a strong response is required to the strengthening evidence in the scientific assessments of the Intergovernmental Panel on Climate Change (IPCC). We accept the IPCC consensus that climate change raises the risk of severe consequences for human health and security and the environment. We note that Canada is particularly vulnerable to the impacts of climate change."
Have the environazis seized the reigns of industrial power, in addition to infiltrating the UN, the science academies of every developed nation and the top research institutes of North America? That just doesn't seem very likely.
Objection: Why should we trust a bunch of contrived computer models that have never had a prediction confirmed? Talk to me in 100 years.
Answer:
Given the absence of a few duplicate planets and some large time machines, we can't test a 100-year temperature projection. Does that mean the models can't be validated without
waiting 100 years? No.
The climate is an extremely complex system. Our observations of it are by no means complete-even with regard to what's going on today.
This is a shortcoming we need to work hard to correct, but it is also an opportunity for validating model predictions: Find a measurement we've never taken, see how the models say it should turn out and then go take it and compare.
Still, there are global temperature predictions that have been validated. We can start with one of the pioneers in climate science. More than 100 years ago, in 1896, Svante Arrhenius predicted that human emissions of CO2 would warm the climate. Obviously, he used a
much simpler model than current coupled ocean-atmosphere global climate models, which run on supercomputers.
Arrhenius overestimated the climate's sensitivity to CO2 by a factor of two. At the same time, he hugely underestimated the degree of warming, assuming CO2 would rise very slowly (who could have predicted the emissions the future held?). Still, it was a pretty impressive early success for models.
Running the clock forward: In 1988, James Hansen of NASA GISS fame predicted that temperatures
would climb over the next 12 years, with a possible brief episode of cooling in the event of a large volcanic eruption. He made this prediction in a landmark paper and before a Senate hearing, which marked the official "coming out" to the general public of anthropogenic global warming. Twelve years later, he was proven remarkably correct, requiring adjustment only for the timing difference between the simulated future volcanic eruption and the actual eruption of Mount Pinatubo.
And, let's face it, every year of increasing global mean temperature is one more year of success for the climate models. The acceleration of the rise is also playing out as predicted, though to be fair, decades will need to pass before such confirmation is inarguable.
Putting global surface temperatures aside, there are some other significant model predictions made and confirmed:
Models predict that surface warming should be accompanied by cooling of the stratosphere, and this has indeed been observed.
Models have long predicted warming of the lower, mid and upper troposphere, even while satellite readings seemed to disagree-but it turns out the satellite analysis was full of errors and, on correction, this warming has been observed.
Models predict warming of ocean surface waters, as is now observed.
Models predict an energy imbalance between incoming sunlight and outgoing infrared radiation, which has been detected.
Models predict sharp and short-lived cooling of a few tenths of a degree in the event of large volcanic eruptions, and Mount Pinatubo confirmed this.
Models predict an amplification of warming trends in the Arctic region, and this is indeed happening.
And, finally, to get back to where we started, models predict continuing and accelerating warming of the surface, and so far they are correct.
It is only long-term predictions that need the passage of time to prove or disprove them, but we don't have that
time at our disposal. Action is required in the very near term. We must take the many successes of climate models as strong validation that their long-term predictions, which forecast dire consequences, are accurate.
If we seek even more confidence, there is another way to test a model's predictive power over long time periods: hindcasting. By starting the model at some point in the past-say, the turn of the 20th century-and running it forward, feeding it confirmed observational data on greenhouse gasses, aerosol, solar, volcanic and albedo forcing, we can directly compare modeled behavior with the actual, observed course of events.
Would a prediction made in 1900 of temperatures for the year 2000 have been validated? Would politicians in 1900 have been wise to heed the warnings of science, had science had today's climate models then?
Clearly, yes.
Objection: Correlation is not proof of causation. There is no proof that CO2 is the cause of current warming.
Answer:
There is no "proof" in science-that is a property of mathematics. In science, what matters is the balance of evidence and theories that can explain that evidence. When possible, scientists make predictions and design experiments to confirm, modify or contradict their theories, and must modify these theories as new information comes in.
In the case of anthropogenic global warming, there is a theory (first conceived more than 100 years ago) based on well-established laws of physics. It is consistent with mountains of observation and data, both contemporary and historical. It is supported by sophisticated, refined global climate models that can successfully reproduce the climate's behavior over the last century.
Given the lack of any extra planet Earths and a few really large time machines, it is simply impossible to do any better than this.
Objection: The earth has had much warmer climates in the past. What's so special about the current climate? Anyway, it seems like a generally warmer world will be better.
Answer:
I don't know if there is a meaningful way to define an "optimum" average temperature for planet Earth. Surely it is better now for all of us than it was 20,000 years ago when so much land was trapped beneath ice sheets. Perhaps any point between the recent
climate and the extreme one we may be heading for, with tropical forests inside the Arctic Circle, is as good as any other. Maybe it's even better with no ice caps anywhere.
It doesn't matter. The critical issue is not what the temperature is, may be or will be. The critical issue is how fast it is rising.
Rapid change is the real danger. Human habits and infrastructure are suited
to particular weather patterns and sea levels, as are ecosystems and animal behaviors. The rate at which global temperature is rising today is likely unique in the history of our species.
This kind of sudden change is rare even in geological history, though perhaps not unprecedented. So the planet may have
been through similar things before-that sounds reassuring, right?
Not so much. Once you look at the impact similar changes had on biodiversity at the time, historical precedent becomes anything but reassuring. Rapid climate change is the prime suspect in most mass extinction events, including the Great Dying some 250 million years ago, in which 90 percent of all life became extinct.
What we know about ecosystems, and what geologic history demonstrates, is that dramatic climate changes-up or down or sideways-are a tremendous shock to the biosphere and cause mass extinction events. That, all in all, is not likely to be a good thing.
Objection: The Kyoto treaty, even if fully implemented, would only save us about a tenth of a degree of future temperature rise many decades from now. What a waste of effort!
Answer:
There are three big problems with this claim.
First, it's a red herring. The purpose of Kyoto is to establish international political and economic mechanisms for dealing with global warming, by taking the first tentative steps toward a difficult goal. You may as well time me walking to the sidewalk where I parked my car bicycle and then tell me at this rate I will never get home.
Second, Kyoto is a step-by-step process. The second phase (much less the third, fourth, etc.) has not even been negotiated yet. How can anyone claim anything about how effective it is going to be? JunkScience.com and other sources of this propaganda are starting
their dubious calculations from the assumption that Kyoto ends in 2012 when round one is over. That is just wrong.
Third, the temperature several decades from now is to a large extent already determined by the current energy imbalance, thanks to extra CO2 already in the atmosphere. Short of a complete cessation of emissions today, there is no foreseeable way to avoid the bulk of the warming "in the pipeline." This is mostly due to the extreme thermal inertia of the oceans and therefore the climate system as a whole. It means that our actions today, or our inaction, will have consequences several decades hence.
Finally, I have a rather personal peeve with people who vociferously criticize any attempt at a solution and yet propose nothing in its place. You'd think if they were so sincerely concerned about how ineffective Kyoto will be (as, frankly, they should be), they would be agitating for more action rather than shrugging their shoulders and saying, "I guess we should just sit it out." It's like a guy standing on the sidewalk watching all his neighbors fight a house fire, saying, "You'll never make it; you don't have enough people."
Shut up and help!
