Global Warming or Just Hot Air? A Dozen Different Views

Earth's temperature has increased by about 1 degree Fahrenheit (0.56 degrees Celsius) in the last century. Most of the warming in the last 50 years is attributed to human activities, according to the U.S. Environmental Protection Agency.

Goldilocks and the Greenhouse What makes Earth habitable? This LiveScience original video explores the science of global warming and explains how, for now, conditions here are just right.

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"The argument about whether there is global warming is over. It is now clear that, for thirty years, we have been in a strong global warming trend at a rate of about 0.2 Celsius per decade for the past 30 years, [meaning] there has been 1 degree Fahrenheit (0.56 degrees Celsius) global warming in the past 30 years. The Earth is now at its warmest level in the period of instrumental data, that is, since the late 1800s."

"Many people have the impression that there is significant scientific disagreement about global climate change. It's time to lay that misapprehension to rest. There is a scientific consensus on the fact that Earth's climate is heating up and human activities are part of the reason. We need to stop repeating nonsense about the uncertainty of global warming and start talking seriously about the right approach to address it.

"The impacts of the changes the climate scientists are predicting are being tested in a number of systems. For plants, it seems that elevated levels of CO2 [carbon dioxide] will increase plant biomass, water use efficiency, and reproductive effort. Some experiments have shown that this includes an increase in pollen production. Since some plants have pollen that is highly allergenic, this could mean increased exposure to allergens and an increase in illness for those who are pollen allergic.

"The most coherent explanation is that climate is changing because of burning of fossil fuels and felling forests. The health, environmental, and economic costs of inaction are rapidly becoming unmanageable. Stabilizing the climate will require a clean energy transition that will also benefit public health, improve energy security, and can become the engine of economic growth for this 21st century.

"The warming of the past several decades has been faster and risen to higher temperatures in the past decades than has been seen in thousands of years. Rising CO2 [carbon dioxide] levels can easily explain the warming, but there is no alternative explanation that does not involve rising CO2 or predict further warming. Scientists have done their job, it is time now to confront the reality of human-induced climate change resulting from emission of CO2 from fossil fuel consumption."

"When we look at the complex environmental systems of our planet, from climate to the polar ice sheets, there will always be lingering uncertainties, and some surprises probably await us. But in the thorough and convincing rebuttal of the last contrary arguments, we have just witnessed a historically important validation of the scientific evidence for human causation of climate warming. And Katrina and the waning polar ice caps remind us how important this is.

"In climate science, we only have two things: data (the past) and models or hypotheses (the future). The data show us that distribution of warming since the mid-1970s is consistent with what one would expect from an enhanced carbon dioxide-related greenhouse effect. The ensemble behavior of our models is that, once this warming is initiated, it tends to take place at a constant (rather than an ever-increasing) rate. Indeed this has been the case for the last three decades.

"Consequently we know, with considerable confidence, the rate of warming for the policy-foreseeable future, and it is about 0.85 degrees Celsius, [1.53 degrees Fahrenheit] per half-century. This is near the low end of projections made by the United Nations. However, there is no known suite of technologies that can affect this rate significantly, so the proper policy is to invest in the future rather than to waste money today in a futile attempt to significantly reduce warming."

"The human brain is a remarkable device that was designed to rise to special occasions. We are the progeny of people who hunted and gathered, whose lives were brief and whose greatest threat was a man with a stick. When terrorists attack, we respond with crushing force and firm resolve, just as our ancestors would have. Global warming is a deadly threat precisely because it fails to trip the brain's alarm, leaving us soundly asleep in a burning bed.

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Sara Goudarzi is a Brooklyn writer and poet and covers all that piques her curiosity, from cosmology to climate change to the intersection of art and science. Sara holds an M.A. from New York University, Arthur L. Carter Journalism Institute, and an M.S. from Rutgers University. She teaches writing at NYU and is at work on a first novel in which literature is garnished with science.