*Post originally written in July 2020.
Anyone that knows me knows I’m incredibly passionate about the issue of Climate Change. I firmly believe it’ll be one of the greatest challenges humans as a species will ever face in our collective existence. I felt the need to present why I felt this way in order to help shed light on why this is such a global, pressing issue. It will require unprecedented global cooperation, innovation, and mobilization in order to manage the worst impacts of Climate Change. I’d like to make this a series of posts: what climate change is and why it’s so bad (why it got my attention in the first place!), innovations/solutions we need to reverse damage we’ve already done and bring emissions down to zero, and how can we mobilize investing and policy, among more. Here’s my attempt at post 1.
My goal for the post is to walk you through a streamlined process that I went through reading books and reports, auditing courses, and spending hours consuming articles and videos on the topic. I felt there wasn’t a single post that laid out all the facts in a chronological and organized fashion that made it easy to understand. What you’ll read below is my outline for how I’ve best understood and structured the topic mentally. I have no agenda here; I’m just presenting the facts.
More full list of sources can be found in the Reading List below!
*Little to none of this is original writing or thoughts and I do not claim any as such. It’s a synthesis of the best resources and data I’ve come across that helped me deepen my understanding of the issue and trends, simply organized in a easy-to-digest format. I recommend reading the source articles to get full detail.
Per NASA, “Global warming” refers to the long-term warming of the planet. “Climate change” encompasses global warming, but refers to the broader range of changes that are happening to our planet, including rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times.
The Greenhouse effect is the natural process that maintains an earth warm enough to sustain life. When electromagnetic solar radiation reaches the earth’s surface, some of it is reflected back into space while some of it is absorbed by the earth’s atmosphere and surface, thus heating the earth. In order to maintain a life-sustaining degree of heat, some infrared radiation is emitted from the earth back towards space, although a portion of that is absorbed by greenhouse gases in the atmosphere. Greenhouse gases create the ‘greenhouse effect’ which warms the earth’s climate. This process typically ensures that the delicate temperature balance of the planet is kept at an optimum. Greenhouse gases – carbon dioxide (CO2), nitrous oxide, methane, and others – are important in sustaining a habitable temperature for the planet if there were absolutely no greenhouse gases (GHGs), the average surface temperature of the Earth would be about -18 degrees Celsius.
Broadly speaking, earth’s atmosphere is made up of oxygen, nitrogen, and water vapor. Water vapor regulates what stays and what goes in Earth’s atmosphere and provides a natural “filter” that just enough energy is retained and the rest escapes. To illustrate, if there was no water vapor in the atmosphere, there’d be no heat and earth would be pretty much a snow globe. If there was too much water vapor in the atmosphere, all the heat beamed down from the sun would be trapped and there’d be runaway warming that would make the planet insufficient to support life. Left to its own accord, water vapor works incredibly well at regulating the earth’s atmosphere and thus its temperature. When CO2 and other greenhouse gasses get absorbed into the atmosphere, CO2 captures the frequencies that water vapor would otherwise let through. Thus, more CO2 in the atmosphere = more frequencies captures = warmer and warmer environment.
This is obviously a broad simplifcaition. For further detail, Dr. Jonathan Foley details: First of all, there are several key greenhouse gases to consider — carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and so-called f-gases (mainly hydrofluorocarbons, chlorofluorocarbons, and other fluorinated gases). It’s not just CO2. Each gas behaves a little differently in the atmosphere, and we need to take that into account. For example, some gases trap heat much more effectively than others, because their molecular structure absorbs infrared radiation better, and they each last a different amount of time in the atmosphere. So to compare them in a consistent, “apples to apples” way, we often convert them into equivalent units by averaging their “global warming potential” over 100 years. (This is a standard tool to compare different greenhouse gases and their impact on climate change. But it does bury a few important points. For example, methane is far more powerful at trapping heat than carbon dioxide, but it doesn’t last in the atmosphere very long. So, in the short term, say 10–30 years, methane is extremely important to climate change. But in the longer term, like a century or two, it’s much less so.) Of our greenhouse gas emissions, carbon dioxide gets most of the attention, and for good reason. It represents about 76% of our greenhouse gas emissions each year. And the lion’s share of it (about 62% of total emissions) comes from burning fossil fuels, including our use of oil, coal, and natural gas. That’s why a lot of the focus on climate change solutions is centered on replacing fossil fuels — it causes about 62% of the problem.
To reconstruct long-term CO2 concentrations, we have to rely on a number of geological and chemical analogues which record changes in atmospheric composition through time. The process of ice-coring allows for the longest extension of historical CO2 records, extending back 800,000 years. The most famous ice core used for historical reconstructions is the Vostok Ice Core in Antarctica. This core extends back 420,000 years and covers four glacial-interglacial periods.
Per Our World In Data, Ice cores provide a preserved record of atmospheric compositions—with each layer representing a date further back in time. These can extend as deep at 3km. Ice cores preserve tiny bubbles of air which provide a snapshot of the atmospheric composition of a given period. Using chemical dating techniques (such as isotopic dating) researchers relate time periods to depths through an ice core. If Looking at the Vostok Ice Core, researchers can say that the section of core 500m deep was formed approximately 30,000 years ago. CO2 concentration sensors can then be used to measure the concentration in air bubbles at 500m depth—this was approximately 190 parts per million. Combining these two methods, researchers estimate that 30,000 years ago, the CO2 concentration was 190ppm. Repeating this process across a range of depths, the change through time in these concentrations can be reconstructed.
Per NASA, Ice cores are scientists’ best source for historical climate data. Other tools for learning about Earth’s ancient atmosphere include growth rings in trees, which keep a rough record of each growing season’s temperature, moisture and cloudiness going back about 2,000 years. Corals also form growth rings that provide information about temperature and nutrients in the tropical ocean. Other proxies, such as benthic cores, extend our knowledge of past climate back about a billion years into the past. Through compositional analysis of ocean/lake sedimentation, fossils, ice cores, coral reefs and tree rings, paleoclimatologists have been able to reconstruct an estimation of the climate conditions of different historical time periods. Analysis indicates the following: Natural warming and cooling cycles over past periods, as well as several deep freeze and greenhouse earth periods. In some cases, major volcanic or meteoric activity was deemed responsible. While the earth has historically experienced “worse” conditions in the form of extreme warming or cooling periods that resulted in mass extinctions, the rate at which warming is occurring, considering the general stability of the last few millennia, is a clear deviation from the trend. In addition, there are no significant natural drivers of this accelerated warming. While a mass extinction is not necessarily imminent, the planet is changing for the worse in that continuation along this trend will not only be disruptive to much of the biological life on the planet, but also to the way of living humans have cultivated for themselves.
Ice core reconstruction indicates that pre-industrial levels of atmospheric carbon dioxide ranged between 275-285ppm, with the highest historical carbon dioxide level peaking at around 300ppm. The current concentration of atmospheric carbon dioxide is 414.50 as of March 2020 and still on the rise. The correlation between the concentration of carbon dioxide and global temperature, as well as the commensurate rates of increase in fossil fuel combustion, unequivocally point to human action as the dominant contributor to greenhouse gas emission.
Per National Geographic, The last time the concentration of Earth’s main greenhouse gas reached this mark, horses and camels lived in the high Arctic. Seas were at least 30 feet higher—at a level that today would inundate major cities around the world. The planet was about 2 to 3 degrees Celsius (3.6 to 5.4 degrees Fahrenheit) warmer. But the Earth then was in the final stage of a prolonged greenhouse epoch, and CO2 concentrations were on their way down. This time, 400 ppm is a milepost on a far more rapid uphill climb toward an uncertain climate future.
The last time the concentration of CO2 was as high as 400 ppm was probably in the Pliocene Epoch, between 2.6 and 5.3 million years ago. Until the 20th century, it certainly hadn’t exceeded 300 ppm, let alone 400 ppm, for at least 800,000 years. That’s how far back scientists have been able to measure CO2 directly in bubbles of ancient air trapped in Antarctic ice cores. It took between a thousand and a few thousand years, at the end of Stage 11, to melt all or most of the Greenland and West Antarctic ice sheets. The whole interglacial lasted 30,000 years, nearly three times as long as ours has lasted so far. So the warming had a long time to build up. That’s the good news. But at 400 ppm, CO2 is much higher now, and it’s still climbing fast. And even if we could stop that rise tomorrow, the planet’s temperature would still climb for centuries.
In my mind, this is one of the most important charts I could point you too to both understand our current levels as it relates to historical periods but also to look at how sharply this has increased over the past ~150 years. If you overlay when the industrial revolution started, it’s clear to see the most recent spike in carbon ppm and rise in global temperatures is driven by anthropogenic (human-induced) causes.
Per NASA, The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels from 280 parts per million to 400 parts per million in the last 150 years.
The current warming trend is of particular significance because most of it is extremely likely (greater than 95 percent probability) to be the result of human activity since the mid-20th century and proceeding at a rate that is unprecedented over decades to millennia. In its Fifth Assessment Report, the Intergovernmental Panel on Climate Change, a group of 1,300 independent scientific experts from countries all over the world under the auspices of the United Nations, concluded there’s a more than 95 percent probability that human activities over the past 50 years have warmed our planet.
Per the EPA, Carbon dioxide (CO2): Carbon dioxide enters the atmosphere through burning fossil fuels (coal, natural gas, and oil), solid waste, trees and other biological materials, and also as a result of certain chemical reactions (e.g., manufacture of cement). Carbon dioxide is removed from the atmosphere (or “sequestered”) when it is absorbed by plants as part of the biological carbon cycle. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2.
Per Dr. Jonathan Foley, Executive Director of Project Drawdown, If we focus on carbon dioxide, it turns out that only ~45% of the annual CO2 emissions stay in the atmosphere, contributing to climate change; the other ~55% is basically soaked up by the oceans (~23%) and land-based ecosystems (~32%). That’s important to reiterate: Over half of our annual CO2 emissions are immediately absorbed by land-based ecosystems and the oceans, dramatically reducing the impact of our activities on climate.
We just spent a lot of time on CO2 and it’s presence in the air and as it relates to emissions, which will connect to impacts we see here on earth (rising temperatures, sea level rise, etc.). If there was any initial doubt, NASA data shows CO2 concentration and the global temperature anomaly is highly correlated.
Significant changes in the concentration of greenhouse gases in the atmosphere have been attributed to pre-industrial periods of global warming or cooling, although those climate events can largely be explained by natural occurrences rather than anthropogenic (human-caused) ones. Natural events that cause a significant alteration in atmospheric composition, such as large-scale volcanic eruptions, have triggered periods of global cooling or warming that may have lasted for months or even years by altering the atmospheric composition to include heat-trapping greenhouse gases or solar radiation-preventing ash particles.
At this point, we now understand the role of CO2 in how the environment warms, both the amount and rapid rate CO2 concentrations have increased in recent years, and that this is human-induced. So what does this all mean for the earth and what changes are we actually observing here? This next section is chart-heavy but will go to show you the overwhelming consensus and clarity in the trends we’re witnessing on earth. Among other things, climate change results in global temperature rise, warming oceans, shrinking ice sheets, glacial retreats, decreased snow cover, sea level rise, declining arctic sea ice, rise in extreme weather events, and increased ocean acidification, among more. Further, these are the 1st order environmental effects. I’d point you to other literature if you want to understand the second and third order effects of what those environmental changes will cause (increased rainfall/flooding, droughts, decreased agricultural yields. forced migration, coral bleaching, biodiversity loss, property damage and loss, etc.).
Another common misconception about climate science is that people assume that we cannot predict or understand these trends due to their massive scale. People dismiss climate alarmism or the climate movement since bold predictions of the past did not come to fruition. However, I’d point out that history proves climate scientists were actually quite accurate in their predictions of future temperatures and impacts on the climate. Whether your local news station or click-bait focused journalists reported the facts as such is an entirely different discussion.
Climate models have accurately predicted global heating for the past 50 years, a study has found.
“We found that climate models – even those published back in the 1970s – did remarkably well, with 14 out of the 17 model projections indistinguishable from what actually occurred,” said Zeke Hausfather, of the University of California, Berkeley, and lead author of the paper, published in the journal Geophysical Research Letters (chart from paper below).
The Guardian summarized the research: The research examines the accuracy of 17 models published over the past five decades, beginning with a 1970 study and including 1981 and 1988 models led by James Hansen, the former Nasa climatologist who testified to the US Senate in 1988 about the impacts of anthropogenic global heating. The study also includes the first four reports by the UN’s intergovernmental panel on climate change (IPCC).
The findings confirm that since as early as 1970, climate scientists have had a solid fundamental understanding of the Earth’s climate system and the ability to project how it will respond to continued increases in the greenhouse effect. Since climate models have accurately anticipated global temperature changes so far, we can expect projections of future warming to be reliable as well.
At this point, hopefully you understand what Climate Change is, that it’s happening, and how rapidly it’s impacting our environment. Further posts will explore what impacts this has on society/business/humanity and what technologies/innovations we’ll need to overcome these staggering challenges. It’s here. It’s happening. It’s not slowing down.
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