for National Geographic News
Whether or not people are heating up the planet, the best course of action is to do something about global warming, some experts are arguing. But others think that's moving too fast.
Peter Tsigaris, a statistician at Thompson Rivers University in Kamloops, Canada, is one of many scientists who favors taking immediate action against global warming. (Get the basics on global warming.)
Tsigaris has made waves in Canada by asserting that doing nothing about climate change is more damaging to the economy than acting on it.
He points to a 2006 report published by England's Government Economic Service.
The report says if people do not act to curb global warming, the impacts of climate change will drain at least 5 percent—and up to 20 percent—of the global gross domestic product each year. (See a map of global warming's impacts.)
By contrast, the cost of action to reduce greenhouse gas emissions and avoid the worst impacts of climate change could be limited to around one percent of the annual global GDP, the report states.
But some experts argue that human-caused global warming is still an assumption, and that not enough is known to act.
The pro-action argument is based on the standard scientific method that includes null and alternative hypotheses.
In the case of global warming, the null hypothesis is that humans are not causing climate change. The alternative is that we are.
Incorrectly rejecting the null hypothesis would mean believing that global warming is caused by people when it's not.
Incorrectly accepting the null—called a Type II error in statistics—would amount to dismissing human causes of climate change even though we are to blame.
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