In a blog devoted to 21st century technology why are we discussing climate change? Because if climate is changing, and the evidence strongly suggests that, it will impact the planet in this century and beyond. Our response to climate change will play a critical role in determining new technologies that we apply to counter changing sea levels, altered precipitation patterns, melting polar and mountain glaciers, and rising temperatures.
For those reading this blog who are skeptical about the science of global warming let’s quickly review what we know from history and what evidence we have today to support the conclusions that climatically we are dealing with the global impact of our technical society on our planet.
Taking the Planet’s Temperature
Humans have been recording earth’s atmospheric temperature only recently. The first temperature recordings date to the 17th century in Europe. By the mid-19th century with colonial expansion, European scientists were faithfully keeping temperature records all across the planet. Prior to the recording of daily temperatures we have no direct statistical evidence of temperature variation on Earth. But we do have lots of historical records mentioning weather phenomenon dating back several thousand years as well as physical evidence drawn from a variety of sources including: tree rings (hundreds to thousands of years), ice cores from glaciers and the poles (thousands to hundreds of thousands of years), sampling of soil cores, rock and fossil records (hundreds to hundreds of millions of years). We also have observations from astronomy to help us “acclimatize.”
Celestial Impacts on Climate
From astronomers we have learned about the Earth’s wobble. If this is not familiar to you let me explain. Our planet tilts on an angle as it orbits the Sun. Sometimes it tilts more and sometimes it tilts less. Each wobble cycle takes 20,000 years. The tilt variable is 22 to 25 degrees. Today we are around 23.5 degrees. When the tilt is less it changes the amount of solar energy that hits each hemisphere as the planet orbits the Sun. The greater the tilt the higher the amount of solar energy absorbed by whichever hemisphere is in its summer phase. The less the tilt the opposite.
In addition our orbit around the Sun is not circular. It is elliptical. Sometimes, therefore, we are closer than the 149,600,000 kilometers (93 million miles). The distance varies by about 5 million kilometers. When the northern hemisphere tilts toward the Sun and we are closest to the Sun, about 147,166,000 kilometers, solar radiation in the hemisphere is more intense. The opposite is true when we are further away at 152,173,000 kilometers.
Scientists have also studied the Sun and been able to determine that its output varies over time. There is a correlation between the solar radiation output and sunspots that cyclically appear on the Sun’s surface. More sunspots means a more active and warmer Sun. Fewer sunspots, a less active and cooler Sun. When the Sun is cooler global temperatures drop.
What the Geological Record Shows Us
Our current continental configuration, that has the bulk of our continental masses in the northern hemisphere, also impacts climate. With large land masses in the north and ocean in the south, the climate in these areas reflects the different energy absorption levels of land versus water. Of course we are talking about continents that move between 1 and 10 centimeters per year and it’s hard to think about any immediate impact from plate tectonics on 21st century climate change. But in terms of geological time the position of continental plates has changed weather.
Our geological and geomorphological science has convincingly shown us that the recent history of our planet has included extensive periods of glaciation with much of the northern and southern extremes of the planet covered in continental glaciers and sea ice. This Ice Age has been cyclical in nature with extensive ice sheets appearing over land areas far more extensive than the remnant ice we see in Greenland and Antarctica today. The cycles of the Ice Age seem to coincide with the planet’s proximity to the Sun and the wobble.
Glacial growth and melting has interesting impacts on the most visible feature of our planet, our oceans. I’ll give you an example. When the last major advance of ice occurred in North America it peaked around 21,000 years ago and as it began to melt it formed an enormous freshwater lake where the current Great Lakes exist. Called Lake Agassiz, this lake’s main outlet was south through the Mississippi river system. An ice sheet dammed up the St. Lawrence River valley so the water couldn’t flow into the Atlantic. When that dam melted and broke Lake Agassiz emptied northeastward into the Atlantic flooding it with fresh water on a colossal scale. What did this do to the Gulf Stream and its companion North Atlantic Drift? The cold fresh water being lighter than the salt water of the Ocean formed a surface layer and completely disrupted the flow of warmer water from the south impacting Europe’s climate. That extra water also raised sea levels by 1.5 meters submerging coastlines and altering plant and animal habitats. You can imagine how disruptive these catastrophic changes could be to weather patterns, precipitation, and habitability.
What Historical Clues Tell Us
For Europeans there is a more recent historic example of climate change. We know that climate from 800 to 1300 A.D. was largely benign compared to a period that followed from 1300 to 1800 A.D. The former has been labelled by climatologists as the Medieval Optimum. Temperatures in Northern Europe appear to have been warmer with feudal Europe enjoying population growth, the emergence of cities, bumper harvests and much more physical evidence pointing to a fairly benign climate. The Vikings of Scandinavia flourished in this period and expanded their range from Northern Europe to Greenland, Iceland and Vinland (Newfoundland and Labrador). While Europe enjoyed a relatively warm and benign climate, evidence from North America shows persistent drought leading to the collapse of the Anasazi and Mayan civilizations in the Southwestern United States and Central America. We know about the drought conditions in North and Central America through tree rings and ocean sediments.
But something happened to the climate starting around 1300 A.D. and we can turn to historical written records to begin to understand what this period, known as the Little Ice Age, was like. We are fortunate that the science of astronomy arose during the period in question. Both in Europe and China solar observations indicated no or little sunspot activity throughout the period. We also have hard science to support these historic observations because we can track the absence of radioactive elements that are byproducts of solar radiation through ice cores where bubbles give us samples of what the air was like when the ice was laid down. The absence of these radioactive elements confirms a cooler Sun.
Since 1800 we have seen a rise in global temperatures generally. Those who are skeptical about global warming often point to the historic evidence that warming and cooling seem to be cyclical and that the 500 years of warming followed by cooling is the norm. That means we are in the natural warming period that will end by 2300 before we plunge back into another little Ice Age. But unlike any earlier period of warming and cooling we now have the rise of our technical society, the Industrial Revolution, and the exploitation of fossil fuel energy and its atmospheric output. This is so recent a phenomenon that we cannot look to historic and geological records to easily find answers. What makes those records valuable to us is that they show that climate is a variable, not a constant and that the physical world impacts climate in a big way.
Burning Fossil Fuels Creates Disequilibrium
In David Archer’s “The Long Thaw” he describes the science behind global warming. Whereas weather beyond a few days is very unpredictable, Archer states that climate is not. Climate science on the other hand is tough work. Archer states, “The state of the warming forecast for the entire globe encompasses so much information that no one human mind could hold it all at one time.” Because of this scientists who study the atmosphere, ocean, biology, forestry, soils, and other disciplines formed the Intergovernmental Panel on Climate Change (IPCC). The IPCC’s latest conclusions are unanimous.
Atmospheric carbon dioxide measured over the past 50 years has steadily climbed from 310 parts per million (PPM) to 380 PPM. Much of that increase is coming from human activity – burning of fossil fuels and deforestation. Fossil fuels contribute 7 billion metric tons of carbon dioxide annually. That represents 1% of the biomass of the planet and is 20 times greater than the carbon represented in all human life on this planet. How does that number compare to the natural carbon cycle within the atmosphere? It is about 1/20th of the total amount of carbon cycled in the normal exchange between atmosphere, ocean and land annually. And while the Earth has found a balance in handling natural exchanges of carbon it is this injection of carbon from fossil fuels, carbon buried in the past, that is upsetting atmospheric equilibrium.
Soaking up this extra carbon is something that the natural world may not be able to do. There is only so much capacity to handle carbon and since the Earth has been doing it without human intervention up until now, through human intervention we will have to try to deal with the difference.
Consequences of Climate Change
1. Local weather will change.
I live in Toronto, a relatively benign climate by Canadian standards. What will happen in Toronto over the next century may make the city more temperate. Our summers will be longer and warmer. We will hit 40 degrees Celsius on many summer days. We’ll run more air conditioning for longer. We’ll probably be able to grow plants we once thought of as exotic and they will survive our winter hibernation period. We’ll see some of our native wildlife vanish and new species from farther south arrive on our doorsteps. We’ll see the spread of insects that normally would have died because of our winters. We may experience variable precipitation and certainly atmospheric disturbances more akin to those that now happen in the U.S. Gulf and Mid-Atlantic states. That will mean greater incidents of tornadoes and severe weather.
That’s the picture of the local weather in Toronto. What will it be like in Greenland? Back in the time of the Viking colonization during the warming period between 800 and 1300 A.D., Greenland could support herds and crops. Today it has only limited capacity to support agriculture. But within this century agriculture on a larger scale will be possible on Greenland.
There is a greater problem with rising temperatures over Greenland and that is the melting of its glaciers. If summertime temperatures rise by 3 degrees Celsius Greenland will melt and we have no climate models to go on today that can predict what that will mean in terms of loss of ice mass. Will it be all of the ice or just some? What we do have right now is the evidence that the ice is melting faster than any of our previous predictions.
2. Polar and mountain glaciers will melt.
In Toronto we will be “getting off easy” compared to Northern Canada where the sea ice is shrinking with longer melts each summer. Greenland’s ice sheets will shed more icebergs as the melt increases glacial fluidity. The added fresh water to the North Atlantic will affect shore currents, fish stocks and the ocean flora and fauna. The permafrost, a contraction that means permanently frozen ground, will no longer exist.
In places like the Andes Mountains of Peru the mountain glaciers that feed the Amazon will vanish changing the dynamics of that river system dramatically. Similarly, the Himalayan glacial water sources for the great rivers of Asia will disappear with the same results as in the Amazon.
Antarctica will see a dramatic decrease in the thickness of its glacial cover. Today Antarctica is less impacted by the warming atmosphere than the Arctic largely because it is surrounded by water with the water acting as a heat sink reducing atmospheric warming. But nonetheless, Antarctica will warm up.
Our current climate models are based on observations of the behaviour of ice in stable climatic periods. We have never witnessed the end of an Ice Age. We may not be able to anticipate just how quickly glaciers can melt.
3. The seas will warm, sea levels will rise and the chemical composition of oceans will alter.
How much warmer? How much higher? How chemically altered?
By 2100 scientists predict a rise of between a half and one meter with the greatest impact on low-lying coastal areas. What is interesting is that not all the rise will be because of meltwater. The ocean is a heat sink and when the air above it warms the surface ocean picks up that heat. Warm water has greater volume than cold water so the increased warmth will contribute to rising sea levels as well.
Who will be impacted? The majority of humanity lives within 160 kilometers (100 miles) of seacoasts. So that means almost all of us but you can quickly name a number of countries and locations where sea levels will have dramatic impact: Bangladesh will virtually disappear, as will Florida, many island nations in the Pacific and Indian Ocean, and Holland. If New Orleans experienced the flood post-Katrina, imagine the consequence of a storm surge accompanied by rising sea levels on that City.
Warming will not stop in 2100 and sea levels, therefore, will continue to rise. So this is just the beginning of a much bigger problem.
In addition to the rise in sea levels, the chemistry of the ocean will change. The ocean is a carbon sink today but increase the amount of carbon and you acidify the ocean impacting life that uses calcium carbonate. All shelled creatures will be affected.
Add to this the potential for methane upwelling from “permanently” stored methyl hydrates that found in ocean sediments. Methane releases into the atmosphere represent another greenhouse gas to add to a warming atmosphere.
4. Permafrost will melt.
The Canadian and Siberian tundra has thousands of square kilometers of permanently frozen ground. This permafrost is not so permanent. We know that permafrost contains quantities of methane and should it melt even more methane will enter the atmosphere further exacerbating the warming.
Why are we concerned about methane? Because there is geological evidence of methane spikes in the atmosphere going back 55 million years when there was a significant change in the Earth’s flora and fauna resulting from a rather rapid warming of the atmosphere.
Are We Doomed?
Sounds hopeless doesn’t it. But it’s not. We are a technical society. We understand the scientific method and how to interpret results of scientific investigations. We have the means to communicate the challenge of a warming planet to all humanity. We may lack the political will at present but as our planet warms we will increasingly recognize the peril we face and implement policy and technologies that can limit the impact. Of course we could be like the frog sitting in a glass pot unaware that he is being boiled to death slowly. But let’s not go there. So in subsequent blogs we’ll look at solutions to climate change.