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Chapter 1

THE SCIENCE

CLIMATE SCIENCE HAS been around for a long time, and the physics behind phenomena such as natural feedback cycles and the greenhouse effect have been understood for close to two hundred years. The evidence that human activity—mainly burning fossil fuels but also agricultural and forestry practices—is contributing to rapid global warming that can’t be explained entirely by natural causes has been building steadily over many decades, to the point of certainty today.

The problem is that many people don’t understand the science; in fact, many don’t even understand how science itself operates. Those who make massive profits or who benefit in other ways from maintaining the status quo often exploit this lack of understanding to convince people that climate change either isn’t an issue or isn’t one worth worrying about. This can be dangerous in an era when everyone with a computer has a public platform.

A common argument is that global warming is just a theory, not a fact—but this arises from a misunderstanding of scientific method. Science is based largely on hypotheses, theories, and laws. A hypothesis is an idea that has yet to be tested. A scientist may speculate on why something occurs or happens in a particular way. The scientist, or scientists, will then develop experiments and observations to test the hypothesis. If those experiments don’t confirm the hypothesis, it’s back to the drawing board. If they do, then the hypothesis could become a theory, or further experiments could be conducted to ensure that all factors have been taken into account.

A theory is based on a tested hypothesis or, more often than not, many hypotheses. Once experiments confirm that the hypotheses accurately describe and predict real-world occurrences, a theory is developed. Because science, understanding, and technology evolve, theories are often revised and occasionally, if rarely, disproven and discarded.

A scientific law describes a natural phenomenon and is often based on a mathematical formula. It doesn’t explain how or why the phenomenon occurs. Like theories, laws can also be revised or overturned as new knowledge becomes available.

Because science is often about trying to disprove theories, our understanding of natural phenomena is constantly being tested. As the great physicist Albert Einstein pointed out, “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.”

This is especially true of a complex field like climate science. With so many variables, conditions, effects, hypotheses, and predictions, it is impossible to be 100 percent certain about any of it. But scientists are now about as certain as they ever get that the earth is warming at an unusually rapid pace and that humans are largely responsible. For the IPCC’s Fifth Assessment Report, released in four chapters in 2013–14, hundreds of scientists and experts worldwide combed through the most up-to-date peer-reviewed scientific literature and other relevant materials to assess “the state of scientific, technical and socio-economic knowledge on climate change, its causes, potential impacts and response strategies.”

They determined that it is “extremely likely,” or 95 percent certain, that humans are a major factor in rapid global warming and that evidence for climate change itself is “unequivocal.” Science rarely gets more certain than that, and the uncertainty only lies in the understanding that there may be undetermined factors or that natural factors could play a larger or smaller role than experiments and observation have illuminated. And, because a large part of climate science is predictive, there is room for variation. But all of the theories surrounding climate change have been and are being constantly tested, with scientists looking for flaws as well as ways that the theories can be confirmed. The overwhelming evidence shows that although the earth’s climate constantly changes, it is now changing, warming, more rapidly than ever, and although natural phenomena such as solar and volcanic activity play a role in climatic changes, this rapid warming can only be explained by considering the major contribution of human activity. Increasingly sophisticated predictive models and observation also show that the extreme weather and other consequences we’re experiencing now will only get worse if we continue to emit greenhouse gases into the atmosphere and damage or destroy the natural systems that absorb and store carbon.

As I’ll show in the next section, this evidence has been building for much longer than many people realize.

Ice Age Studies, Feedback Loops, and the Greenhouse Effect

SCIENTIFIC UNDERSTANDING OF the greenhouse effect isn’t new. French mathematician and natural philosopher Joseph Fourier discovered in 1824 that the earth’s atmosphere retains heat that would otherwise be emitted back into space by infrared radiation. Although he didn’t call it the greenhouse effect, he explained his concept by comparing the earth and its atmosphere to a box with a glass cover. It’s a simplistic comparison, and as the American Institute of Physics points out in an excellent summary of the history on its website (from which some of this section is drawn), a glass box or greenhouse does not function in entirely the same way as the earth and its atmosphere.¹

Fourier’s research inspired other scientists to consider the phenomenon. In 1859, Irish-English scientist John Tyndall began studying the ability of gases such as water vapor, carbon dioxide (then known as carbonic acid), ozone, and hydrocarbons to absorb and transmit radiant heat.² On finding that water vapor, ozone, and carbon dioxide, or CO₂, absorbed heat radiation better than gases such as oxygen, hydrogen, and nitrogen, he theorized that fluctuations in water vapor and carbon dioxide could affect global climate. He also discovered the idea of heat islands, by noting that the city of London was warmer than its surroundings.

Some years later, self-taught British scientist James Croll observed that dark surfaces such as soil, rock, and trees hold heat from the sun, whereas snow and ice remain cool, and that as a region cools, wind patterns change, which could affect ocean currents.

Much of the research to this time was aimed at understanding the causes of ice ages. A major breakthrough in our understanding of the effect of greenhouse gases occurred in 1896. Croll’s ideas led Swedish scientist Svante Arrhenius to surmise that a drop in Arctic temperatures could cause land that had been bare in summer to remain covered in ice year round.³ This ice would reflect more of the sun’s heat back into space, lowering the temperature even more, thus creating a positive feedback cycle. He then observed that water vapor could also cause a feedback loop, as warmer air puts more water vapor into the atmosphere, and because water vapor holds heat in, more warm air is created. Because CO₂ also absorbs heat radiation, Arrhenius concluded that adding CO₂ to the atmosphere would contribute to this feedback cycle. Thus, burning fossil fuels and increasing CO₂ emissions into the atmosphere could increase water vapor, causing global average temperatures to rise.

Arrhenius wanted to understand what could cause an ice age, and his studies led him to conclude that cutting CO₂ in the atmosphere by half could cause one. But he also calculated what would happen if the amount was doubled by burning fossil fuels, and concluded that this would cause a 5-or-6-degree-Celsius (9-or-10.8-degree-Fahrenheit) increase in global average temperatures—an estimate surprisingly close to the one climate scientists came up with using much better computer models one hundred years later.

A year after Arrhenius published his findings, American geologist Thomas Chamberlin examined the earth’s carbon cycles more deeply, and according to the American Institute of Physics, wrote that ice ages are “intimately associated with a long chain of other phenomena to which at first they appeared to have no relationship.” It’s a concept that indigenous peoples have taught me, and one that I often talk and write about: Everything is interconnected.

In his “very speculative” paper, published in 1897, Chamberlin hypothesized that CO₂ could affect feedback cycles that bring about ice ages. The complexity of his ideas involved looking at the effect of volcanoes as they spew CO₂ into the air, and what happens when volcanic activity is lower and carbon is absorbed and stored by minerals, plants, and oceans, called carbon sinks. Because the atmosphere contains only a small fraction of the earth’s carbon compared to these carbon sinks, and carbon cycles through the atmosphere every few thousand years, Chamberlin proposed that climate conditions “congenial to life” are in a delicate balance.

At the time, however, it was believed that natural forces, such as solar activity and the ability of oceans to absorb and store carbon, were far more important factors and that CO₂ had an insignificant influence compared to water vapor. Many scientists believed climate was self-regulating and that small changes to atmospheric composition could not alter climate over brief time periods. Any CO₂ that human activity did emit into the air would be absorbed quickly by oceans (and, to some extent, forests and peat bogs)—which was mostly true at the time, when far smaller amounts of fossil fuels were being burned. Some also argued that excess atmospheric CO₂ would fertilize plants and create more lush life—which is also true, to a point. Although the notion that human activity, such as burning ever-increasing amounts of fossil fuels, could not affect a self-regulating climate has been thoroughly disproven by modern science, many people still make the same outdated arguments today.

As with earlier scientific investigations, most climate science in the first half of the twentieth century was driven by a desire to explain the causes of ice ages. In the 1950s, scientists started to get an idea of the bigger picture. In 1956, Maurice Ewing and William Donn, at New York’s Lamont Geological Observatory, were also trying to explain ice ages, in particular the abrupt end of the most recent one. In looking at feedback cycles in the Arctic, they speculated that a complex set of circumstances could lead to rapid climate change over the next few hundred or thousand years. But the change they saw was the coming of another ice age.

Their theories were controversial and often criticized, but they did serve to spark a renewed interest in climate science, more testing of theories, and wider acceptance of the idea that changes in Arctic ice sheets and snow cover could cause rapid changes in planetary surface conditions.

By the 1950s, researchers in the Soviet Union were using this growing scientific knowledge to consider ways to deliberately alter local climatic conditions, by “making Siberia bloom by damming the Bering Straits, or by spreading soot across the Arctic snows to absorb sunlight,” according to the American Institute of Physics. This led Leningrad climatologist Mikhail Budyko to examine the ways in which human influences could be amplified by feedback loops. As a result of his studies, he was one of the first scientists to raise concerns about the potential major effects of burning fossil fuels and other human activities. In 1961 and 1962, he published two books warning that growing energy use will warm the planet and cause the Arctic ice pack to quickly disappear, contributing to further feedback cycles.

In the mid-1960s, Budyko developed models that showed relatively small changes in global average temperatures and polar snow cover could cause feedbacks that would cause dramatic increases in temperature and sea levels. Researchers in Sweden, New Zealand, and the U.S. were arriving at similar conclusions. Although many of the studies pointed to a warming planet, some speculated that changes in solar activity or dust in the atmosphere could cause another ice age.

Over the next few decades, climate scientists developed increasingly sophisticated computer models to examine the effects of greenhouse gases on climate—especially as computer technology improved along with scientific knowledge. It also became easier to study other planets, such as Venus, which was covered in an atmospheric blanket of water vapor and CO₂, producing a massive greenhouse effect, and to examine past climatic events.

In 1973, a U.S. probe to Mars led the famous astronomer Carl Sagan and others to conclude that the red planet had undergone major shifts between cold and hot. Around the same time, analyses of seabed clay layers showed that Earth’s ice ages had occurred in roughly 100,000-year cycles. Although these roughly matched calculations by Serbian scientist Milutin Milankovitch in the early twentieth century, research also demonstrated that Milankovitch’s theories about the effects of subtle shifts in the earth’s orbit were not sufficient to explain the massive changes. However, natural cycles including ice buildup and flow, warping of the earth’s crust and sea level changes, combined with orbital shifts, could explain the ice age cycles.

Scientists also started looking into the effects of clouds, volcanic dust, smoke, and other aerosols on climate. Some initial studies led researchers such as NASA’s James Hansen to speculate that the world could be headed for a cooling phase. This short-lived theory, which didn’t take into account factors such as ocean circulation, provides ammunition for climate change deniers to this day.

By the late 1970s, many scientists were convinced that Earth was getting warmer, but although many proposed convincing hypotheses, no one was able to accurately and definitively prove the cause. I spoke with science writer Isaac Asimov about it in 1977 on CBC Radio’s Quirks & Quarks.

By the 1980s, computers were becoming sophisticated enough that it was possible to go beyond looking at climatic conditions in isolation to examine the numerous interconnections that can affect systems as a whole. More knowledge was also being gleaned from seabed and ice cap core samples, which allowed scientists to examine regular ice sheet advances and retreats over hundreds of thousands of years. Although exact causes of current warming were still elusive, many experts were starting to agree that the unusually rapid warming they were seeing would bring about increases in the incidence and severity of heat waves, flooding, droughts, and storms—which did indeed start to occur worldwide. Because warming was not uniform but rapid, causes such as solar activity could be ruled out.

By the late 1980s, the theory of global warming and its human contributions had become well established in the scientific community. In 1989, the CBC television show I host, The Nature of Things, did its first global warming program, and I also hosted the five-part radio series It’s a Matter of Survival, which was in part about climate change. The response to the latter (more than seventeen thousand letters in pre-email days) was so overwhelming that my wife, Tara, and I decided we had to do more than just talk about environmental problems; we had to do something. So we gathered a group of people to discuss ideas and, out of that, the David Suzuki Foundation was formed in 1990.

As computer models and research methods improved, along with the body of scientific knowledge, complexity increased. How were biological systems affected by climate and CO₂, and how in turn did they affect climate and carbon? What impacts would all of this have on agriculture, forestry, and spread of disease?

By the 1990s, studies of the Arctic showed that twentieth-century warming was far greater and more rapid than anything seen in at least the past four hundred years.

Although scientific models and observations were by this time aligning, and most experts were able to confidently conclude that the planet was warming at an unusually fast rate, in part because of the greenhouse effect, the theories still had their critics. Convinced that natural self-regulation would overcome any human effects on climate over the long run, Massachusetts Institute of Technology (MIT) meteorologist Richard Lindzen set out to challenge the way models accounted for the effects of water vapor. Advances in satellite technology and data would later confirm the climate models and prove Lindzen wrong. He continued to look for flaws in the models, and although much of the modeling data were confirmed, his efforts at least made scientists work to improve models and to confirm data through other methods, including paleoclimate studies.

Numerous models with a wide range of varying parameters all confirmed that adding greenhouse gases to the atmosphere would cause global warming.

Michael Mann and the Hockey Stick Graph

IN 1998, UNIVERSITY of Virginia climate scientist Michael Mann, with Raymond Bradley of the University of Massachusetts Amherst and Malcolm Hughes of the University of Arizona, examined paleoclimatic data by studying ice cores, tree rings, and corals, as well as more recent thermometer readings. In doing so, they were eventually able to reconstruct Northern Hemisphere temperatures going back one thousand years. Mann later worked with the University of East Anglia’s Philip Jones to chart temperatures for the past two thousand years. They found conclusively that global mean temperatures spiked rapidly starting in the early twentieth century, just as industrial and other human activities were releasing ever-increasing amounts of CO₂ and other heat-trapping gases into the atmosphere.

The graph they created, which was used in the IPCC’s Third Assessment Report, in 2001, looked like a hockey stick, with a long, steady line that took a sudden jump upward at the end. Although many other scientists confirmed the results, Mann’s work became a target for those opposed to prevailing theories of anthropogenic climate change. Attackers included politicians, pundits, a few scientists, and two Canadians: former mining company executive and consultant Steve McIntyre and economist Ross McKitrick. Although subsequent research found that the Canadians were correct in pointing out some statistical errors, the failings were minor and did not significantly affect the overall results. Several studies found more serious errors in McKitrick and McIntyre’s methodology, and dozens of subsequent studies using various methods and records have since confirmed Mann’s original analysis, with only slight variations.

Another report by aerospace engineer Willie Soon and astronomer Sallie Baliunas, published in the journal Climate Research, claimed that the Northern Hemisphere was warmer during the medieval period than Mann estimated, but their methodology and data, and the publication’s peer-review process, were found to be lacking, leading to the resignation of several of the journal’s editors and an admission by the publisher that the article should not have been accepted as is. Soon has received much of his funding from fossil fuel companies, and Baliunas has been affiliated with a number of fossil fuel–funded organizations.

As Mann told Scientific American in 2005, “From an intellectual point of view, these contrarians are pathetic, because there’s no scientific validity to their arguments whatsoever. But they’re very skilled at deducing what sorts of disingenuous arguments and untruths are likely to be believable to the public that doesn’t know better.”⁴

The IPCC and Global Efforts

IN RESPONSE TO the increasing knowledge—and alarm—about global warming, the World Meteorological Organization and UN Environment Programme set up the Intergovernmental Panel on Climate Change in 1988 at the request of member governments. According to the IPCC website, its goal was “to prepare a comprehensive review and recommendations with respect to the state of knowledge of the science of climate change; the social and economic impact of climate change, and possible response strategies and elements for inclusion in a possible future international convention on climate.” Under its governing principles, its assessments were to be “comprehensive, objective, open and transparent”; based on scientific evidence; and “neutral with respect to policy, although they may need to deal objectively with scientific, technical and socio-economic factors relevant to the application of particular policies.”

Its First Assessment Report, in 1990, provided much of the impetus for the formation of the United Nations Framework Convention on Climate Change (UNFCCC), “the key international treaty to reduce global warming and cope with the consequences of climate change.” It has since produced many comprehensive assessment reports, including the 1995 Second Assessment that provided materials used by negotiators for preparation and adoption of the Kyoto Protocol in 1997. The Third Assessment was released in 2001 and the Fourth in 2007. The IPCC was awarded the Nobel Peace Prize in 2007.

With each assessment, the science has become more robust, and the number of scientists, writers, and contributors has grown to include experts from around the world, with topics covered becoming increasingly broad.

The Fifth Assessment Report was released from September 2013 to November 2014 in four chapters (1. current science, 2. impacts, 3. strategies to deal with the problem, and 4. a final report synthesizing the three chapters). It showed more scientific certainty than in 2007, when the Fourth Assessment was released, that humans are largely responsible for global warming—mainly by burning fossil fuels and cutting down forests—and that it’s getting worse and poses a serious threat to humanity. It contained hints of optimism, though, and showed that addressing the problem creates opportunities.

Scientists are cautious. That’s the nature of science; information changes, and it’s difficult to account for all interrelated factors in any phenomenon, especially one as complicated as global climate. When they say something is “extremely likely” or 95 percent certain—as the Fifth Assessment Report did regarding human contributions to climate change—that’s as close to certainty as science usually gets. Evidence for climate change itself is “unequivocal.”

The first chapter alone cited 9,200 scientific reports in 2,200 pages, stating, “It is extremely likely that human activities caused more than half of the observed increase in global average surface temperature from 1951 to 2010.” It also concluded that oceans have warmed, snow and ice have diminished, sea levels have risen, and extreme weather events have become more common.

The report also dismissed the notion, spread by climate change deniers, that global warming has stopped. It was thought to have been slowing slightly because of natural weather variations and other possible factors, including increases in volcanic ash, changes in solar cycles, and oceans absorbing more heat. But improvements in methods to measure sea surface temperatures led the U.S. National Oceanic and Atmospheric Administration (NOAA) to conclude in 2015 that oceans were warmer from 1998 to 2014 than previously thought and that a much-touted slowing or hiatus in warming didn’t occur.⁵ That study itself was challenged by a February 2016 study published in Nature Climate Change, which did find evidence of a slowdown in the rate of warming, though not a halt.⁶ It also found the slowdown has probably ended. One thing the scientists and their studies confirm is that none of it means climate change is any less of a worry. In fact, the warmest ten years have all been since 1998 (itself an unusually warm year, and one that deniers have desperately cherry-picked as a starting point to claim that warming stalled), and in 2013, carbon dioxide levels rose by the highest amount in thirty years.

According to the IPCC Fifth Assessment Report, an increase in global average temperatures greater than 2 degrees Celsius above preindustrial levels would be catastrophic, resulting in further melting of glaciers and Arctic ice, continued rising sea levels, more frequent and extreme weather events, difficulties for global agriculture, and changes in plant and animal life, including extinctions. The report concluded we’ll likely exceed that threshold this century, unless we choose to act. Subsequent research has shown that 2 degrees is too conservative and that warming over 1.5 degrees will probably lead to disaster. We’re almost at 1 degree already!

The reasons to act go beyond averting the worst impacts of climate change. Fossil fuels are an incredibly valuable resource that can be used for making everything from medical supplies to computer keyboards. Wastefully burning them to propel solo drivers in cars and SUVs, and other inefficient energy uses, will ensure we run out sooner rather than later.

Nations working together to meet science-based targets to cut global warming pollution and create clean, renewable energy solutions would allow us to use our remaining fossil fuel reserves more wisely and create lasting jobs and economic opportunities. Energy conservation and clean fuels offer the greatest opportunities. Conserving energy makes precious nonrenewable resources last longer, reduces pollution and greenhouse gas emissions, saves consumers money, and offers many economic benefits.

Shifting to cleaner energy sources would also reduce pollution and the environmental damage that comes with extracting coal, oil, and gas. That would improve the health of people, communities, and ecosystems, and reduce both health care costs and dollars spent replacing services nature already provides with expensive infrastructure. Reducing meat consumption, which contributes to global warming, is also beneficial to human health.

The fast-growing clean energy and clean technology sectors offer many benefits. Improved performance and cost reductions make large-scale deployment for many clean energy technologies increasingly feasible. Worldwide spending on clean energy in 2013 was $207 billion.

By 2014, Germany, the world’s fourth-largest economy, was getting a third of its energy from renewable sources and had reduced carbon emissions 23 percent from 1990 levels, creating 370,000 jobs.

The 2015 Paris Agreement

FROM THE END of November to December 12, 2015, government ministers, negotiators, climate experts, and world leaders convened in Paris, France, to consider the implications of the IPCC’s Fifth Assessment Report and to agree on how to deal with its findings. It may well have been the world’s last chance for a meaningful agreement to shift from fossil fuels to renewable energy before ongoing damage to the world’s climate becomes irreversible and devastating.

The nations that met in Paris are responsible for more than 95 percent of global emissions. Although it’s far from perfect, the agreement they came up with marks a significant achievement. When nations last attempted a global climate pact—in 2009, at COP15 in Copenhagen, Denmark—negotiations broke down and the resulting declaration was considered a failure. The Paris Agreement, in process and outcome, was a dramatic improvement—a product of the growing urgency to act on the defining issue of our time. It’s the first universal accord to spell out ways to confront climate change, requiring industrialized nations to transition from fossil fuels to 100 percent renewable energy by 2050 and developing nations by about 2080.

Before meeting in Paris, governments drafted plans to reduce national carbon emissions beginning in 2020. One goal of the negotiations was to develop a review mechanism to encourage countries to improve targets over time. That was achieved, giving hope that reductions will keep global temperatures from rising more than 2 degrees Celsius above preindustrial levels. In fact, the newly revised limit of 1.5 degrees is acknowledged as a target for future goal setting. Although the commitments aren’t enough to achieve either goal, improving targets every five years—as is called for in the pact—will get us closer. Past experience shows that once a commitment is made to address a crisis, many unexpected opportunities and solutions arise.

Still, getting the world back on track will not be an easy task, especially as it requires action on commitments from nations that haven’t always lived up to their word. The world’s largest greenhouse gas emitter, China, was criticized throughout the conference for trying to water down requirements for a common emissions-and-targets reporting system and opposing the requirement for countries to update emissions-reduction goals every five years, advocating instead for voluntary updates.

Compromises produced a final product that fell short of assigning liability for past emissions and providing dependable “loss and damage” payments to nations already suffering from the effects of climate change. And success can’t be achieved without ongoing pressure to ensure targets are met and become more ambitious over time. Despite these shortcomings, the Paris Agreement was a leap forward in the fight against climate change. Funding for vulnerable and developing nations, plans to ratchet up ambition at regular intervals, and recognition of the role of indigenous knowledge will play major roles in future action.

The commitment should also inspire people at all levels of society to propose ways to speed up the shift to clean, renewable energy and reduce waste through greater energy efficiency. Although governments and industry must do a lot of the heavy lifting, it’s up to all of us to ensure that the planet we want—with clean air, safe water, fertile soil, and a stable climate—stays within reach, for our sake and the sake of our descendants.

Of course, climate science goes beyond determining that the world is rapidly warming to catastrophic levels and that human activity is a major contributor. Scientific research and analysis are also examining the current and potential consequences of global warming, the impacts on various natural systems and human endeavors, the feedback loops that are created from those impacts, and the potential solutions, among other elements of this complex and disturbing phenomenon.

In the next chapter, we’ll look at some of those impacts and what they mean for our world.