Tomorrow is the longest day of the year, the official beginning of summer. But the lake out in front of our house is still frigid. I\’ve tried wading in it.
On the longest day, the sun is more directly overhead than at any other time of the year. The sun\’s rays will never be warmer. So shouldn\’t this be the middle of summer, with an equal period before and after this day?
Scientists explain that the lag of the seasons has to do with the earth acting as a “heat sink.†It takes time to warm the lake and the land. Although the days have started growing shorter, land and water can to continue to absorb warmth, which warms the air, which makes July and August hotter than May and June.
On a smaller scale, other things act as heat sinks. When we lived in Toronto, we had a brick house. All day long, its south wall soaked up sunshine. That wall exuded warmth long after sunset. The house didn\’t cool off until around 4:00 a.m.
Which, in summer, didn\’t give us many hours of comfortable sleep.
Urban and rural climates
Entire cities act as heat sinks. The same amount of solar heat falls on rural fields and forests as on the concrete and masonry and blacktop in cities. But night-time temperatures drop quickly in the country, while cities continue to swelter in stored heat. Compare the temperature after dark in a tent, say, with a downtown sidewalk.
In winter, cities not only act as heat sinks, they generate their own heat. Furnaces heat buildings; buildings radiate heat into the environment. Cars burn gasoline. The temperature in crowded cities can be five to ten degrees warmer than the surrounding countryside. From the air, Toronto and Windsor look like brown puddles in a snow-white sea.
Comparing city and country temperatures, it\’s obvious to everyone that we humans can affect climates on a small scale.
Tragically, many otherwise intelligent people still deny that we humans could be affecting the climate globally.
Ignorance or apathy?
Despite massive accumulation of scientific evidence, few nations have seriously tackled the implications of global climate change.
Canada did ratify the Kyoto Accord in December 2002. But it has otherwise done next to nothing to reduce greenhouse gases. Indeed, emissions have continued rising since the Accord was drafted in 1997.
Stephen Harper has said that if his party forms the next Canadian government, it will rescind Kyoto.
The United States Senate voted against Kyoto 95-0.
The convention requires 55 per cent of world\’s nations, producing 55 per cent of the world\’s greenhouse gases, to sign on before it comes into force. So far, 74 nations have signed. But two – unlikely bed-mates, the U.S. and Russia – have refused. And between them they account for 53 per cent of the world\’s greenhouse gases.
Effectively, two nations have a worldwide veto.
Inevitably, a certain number of scientists decry the Kyoto Accord as useless, flawed, or even wrong. Just as there are still scientific studies proving that tobacco smoking does not contribute to lung cancer. Just as there is still a Flat Earth Society.
It\’s always possible that a minority may be right, and the majority wrong. After all, only a tiny minority originally suspected that heat trapped in the atmosphere by “greenhouse gases†– mainly carbon dioxide, methane, and synthesized fluorocarbons – could cause climate change. That minority, though, has since swelled to an overwhelming majority.
Greenhouse gases
There is no debate over the earth getting warmer. The debate is over the cause, and its implications.
We now know with certainty that greenhouse gases and higher temperatures go together. For the last decade, a European team has drilled into a three-kilometre-deep ice dome in Antarctica. Currently, they are analyzing ice cores 740,000 years old.
The cores reveal that the earth goes through cycles of heat and cold, probably influenced by eccentricities in the earth\’s orbit around the sun. Each cycle lasts about 100,000 years – an ice age followed by a period of warming.
By analyzing tiny bubbles of air trapped in the ice, the team can also determine the composition of the atmosphere over those 740,000 years.
Their conclusion – when temperatures rise, so do the levels of carbon dioxide and methane.
Which one causes which? No one knows. But there is no question about the relationship.
Nor is there any question that the levels of greenhouse gases in the atmosphere today are “geologically incredible,†according to professor Jerry McManus of the Woods Hole Oceanographic Institution.
Effects of human technology
In the past, greenhouse gases had a natural cause – mostly volcanoes. Today, we humans are the cause. Since the Industrial Revolution, by burning coal, oil, and natural gas, we have added to natural emissions the emissions of plants and animals who died millions of years ago. Carbon dioxide levels are currently over 350 parts per million – 50 per cent higher than just 200 years ago. Methane levels have doubled.
“I can\’t say that carbon dioxide levels are driving temperatures up,†said Eric Wolff, a senior scientist on the Antarctic drilling team. “All I can say is that the two go together. And it scares the hell out of me, frankly.â€
In spite of this evidence, though, political leaders prefer to play games with economic numbers.
Kyoto will not solve global warming. The most it can do is to take emissions back to the 1980s –not such a bad time, all things considered. But it is at least a step in the right direction.
Of all the species on earth, only two have ever managed to affect the world\’s climate. The first was microscopic algae in the oceans. When they began producing oxygen as a waste product of photosynthesis, they made life possible for millions of new species.
We are the second. Let\’s hope our technological prowess doesn\’t start to reverse the algae\’s gift of life.