Scientists tell us the Earth is warming and we’re causing it. Oceans are rising, glaciers are melting, plants and animals are becoming extinct and millions of people are likely to have to move.
In the last 150 years, human activity has caused carbon dioxide levels to rise from about 280 parts per million to about 390 parts per million.
Carbon dioxide and other naturally occurring greenhouse gases, such as water vapor, methane and ozone, make the Earth on average about 59 degrees warmer than it would be otherwise.
Without them, the Earth would be an ice ball.
Industrial production, the burning of fossil fuels, deforestation and urbanization have not only increased the levels of greenhouse gases but added new ones. The result has been a temperature rise of about 1.5 degrees so far and the increase is accelerating.
The Intergovernmental Panel on Climate Change, using the work of thousands of scientists worldwide, forecasts further temperature increases in the next 90 years of between 2 degrees and 11.5 degrees.
It also forecasts sea level rises of between 7 inches and 2 feet.
The wide range reflects the differences in various models and in possible policy choices by governments.
So far, all the models appear to be underestimating the effects. The Greenland ice cap is melting at three times the expected rate. It has enough water to raise the sea level 21 feet. Arctic ice also has shrunk dramatically.
Some skeptics think there is no heat-trapping effect from greenhouse gases. These are people who are ignorant of elementary science. Gases like carbon dioxide, methane and water vapor, by trapping some of the heat radiated from the Earth’s surface, warm the Earth much like a blanket would warm you if you were sitting outside on a cold day. These principles have been well understood since the 19th century.
Doubters point out that there have been wide fluctuations in the Earth’s temperature and in sea levels in the last several hundred million years. The causes include massive volcanic eruptions, asteroid impacts, the proliferation of plants and geological processes that sometimes increase and sometimes decrease carbon dioxide levels.
Worse has happened before.
Why worry?
What’s different now is that a once tiny human population of a few thousand hunter-gatherers could just walk somewhere else if they didn’t like the climate.
Also, these factors from past eons don’t explain the last century’s unusual warming.
What about the claim that temperatures declined over the last decade? Although 2008 was relatively cool, the last decade was the hottest on record, and 2009 was another hot year. Worldwide, the eleven warmest years on record all occurred during the last 13 years, 1997 to 2009.
Skeptics here aren’t worried because the pattern for the U.S. is less strong. Though average annual temperatures have tended sharply upward, year-to-year numbers fluctuate and we can expect short downward trends amid an overall upward trend.
A pause during the last decade is scant evidence against the upward trend. A chart of the S&P 500, which also has substantial year-to-year variation, shows similar behavior.
Skeptics find it baffling that, as the Earth warms overall, some areas like the U.S. have been only mildly affected, so far. Portions of the Antarctic and Greenland have even cooled somewhat.
This happens because wind and water redistribute the Earth’s heat in a complex and uneven way. Meanwhile, the Antarctic ice shelves are breaking up, and the glaciers, which are rivers of ice, speed ever faster into the sea.
The science is clear and we’re seeing the impact of glaciers shrinking worldwide, sea levels rising and animals and plants moving toward the poles.
Why is there still so much public confusion?
We’ve seen it all before. For decades skeptics denied that smoking caused lung cancer. Many people still deny that excess caloric consumption leads to obesity. After years of strident denying of scientific proof, the National Football League has finally admitted that game-related concussions cause long-term brain damage in their players.
Like climate change, the details are complex. It takes some scientific background to sort through the claims and counter-claims, and economic interests are threatened.
The Earth has gotten markedly warmer in the last century. Human activity caused it. This will continue and the real issue is, what should we do about it, if anything?
We need to understand the costs and benefits of these and other ideas so we can choose wisely. Here is where we in the business community, using our knowledge and experience to act in the public interest, can literally change the world.
Thorp is president of Newport Beach’s Edward O. Thorp & Associates, author of “Beat the Dealer” and “Beat the Market” and is professor emeritus of mathematics and finance at UC Irvine.
