Melanie Fitzpatrick is a climate scientist with the Union of Concerned Scientists.
False claims of global-cooling and climate-conspiracy theories suffered a major blow this month with the release of new temperature data and yet another investigation debunking wild accusations against climate scientists.
At the same time, a volcanic eruption in Iceland demonstrated what real global cooling could look like, but volcanoes won't be enough to save us from the all-to real threat of climate change.
For a number of years, global warming contrarians have pointed to 1998, the hottest year on record, to make their case that temperatures have fallen since then. But they conveniently ignore the long-term upward trend in average global temperatures over the past several decades, while overemphasizing the expected natural fluctuations that make individual years somewhat hotter or colder than average.
In fact, the world just experienced one of the hottest months on record. The National Oceanic and Atmospheric Administration (NOAA) announced that last month was the warmest March in its record book, which stretches back to the 1880s. The average global monthly temperature was 1.39degrees Fahrenheit above the 20th-century average for March. While we can't draw strong conclusions from a single month, the string of record-setting average temperatures like this is a harbinger of climate change.
Spring is arriving earlier, just as climate scientists have projected. In northern states such as Maine, Wisconsin and Michigan, the average temperature in March was more than 5 degrees F higher than historic norms. With earlier springs than just half a century ago, plants are flowering earlier, downpours are becoming heavier, and, in northern states, rain is more likely to fall than snow. These changes are disruptive and costly for us and they threaten the survival of many plants and animals.
Climate science contrarians also have been attacking scientists personally and making false claims about the contents of emails stolen from the Climate Research Unit at the University of East Anglia in England. These specious claims have been refuted by scientists, university inquiries, and independent sources such as the Associated Press and Factcheck.org, but the contrarians have persisted in spinning their conspiracy theories.
The University of East Anglia just released an independent review of the stolen emails. The review did include some criticism of how the scientists did their work, but it concluded that climate scientists did not manipulate their data or findings. Previous investigations by Penn State University and the British Parliament also cleared scientists of wrongdoing.
The response from contrarians? They insist the independent investigators are party to the conspiracy. When will these conspiracy-mongers stop this nonsense? Perhaps never. After all, some people believe the United States faked the Apollo Moon landing.
The Ash Cloud
If contrarians want to find a true potential source for global cooling, they need look no further than the massive ash cloud from Iceland's Mt. Eyjafjallajökull. When sulfur dioxide from volcanic eruptions enters the stratosphere, it converts into tiny sulfuric acid particles that act like mirrors, reflecting sunlight back into space and cooling the planet. Volcanoes that emit the right size particles into the right part of the atmosphere for a long enough time can cool the climate for several years. That happened in 1991 in the Philippines when Mt. Pinatubo erupted.
But Eyjafjallajökull's eruption pales in comparison to past climate-cooling volcanic eruptions. And even if a volcanic eruption released enough sulfur dioxide to temporarily cool the planet, the heat-trapping carbon dioxide from burning fossil fuels and destroying forests would still pose a significant threat. Unlike volcanic ash and sulfur compounds, which will settle out of the atmosphere within a few weeks or years, carbon dioxide remains in the atmosphere for decades and even centuries.
Ultimately our fate is up to us. Yes, there are uncertainties about how rapidly the Earth will warm, but the biggest uncertainty is the amount of heat-trapping emissions we will allow to go into the atmosphere. Allowing emissions to continue to grow could lock us into costly climate disruption. Conversely, we could dramatically reduce heat-trapping emissions by switching from fossil fuels to renewable energy sources. We can't avoid all climate change, but we can -- and should -- avoid its worst consequences.
(The opinions expressed in this commentary are solely those of the author.)
By Melanie Fitzpatrick
Special to CBSNews.com
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