WHY TV WEATHER PEOPLE LIKE MYSELF DON'T TALK ABOUT GLOBAL WARMING
Short answer: It's too complicated. But for all you scientific minds out there: here is a brief synopsis:
Many of us do chat about global warming at public forums, club meetings, and the like, but 3 minutes on the air is no place to broach such a sea of topics-within-a-topic. What we can say with a high degree of confidence is that global warming is real and appears to be accelerating. It's also very likely that human activity, particularly the burning of fossil fuels, is a significant contributor in the increased levels of carbon dioxide in the atmosphere. What is less certain is HOW significant our role is; it's very difficult to quantify our place in this increase and manmade greenhouse gasses total impact versus other natural processes which may or may not be going on; there are some physicists who claim variations in solar radiation input and the wobble in the earth's orbit may also contribute to warming, as well as gas emissions from volcanic activity. But it's fair to say most meteorologists, climatologists, physicists and atmospheric chemists think we play a large part in this warming.
The evidence of the warming itself is nearly incontrovertible. Most glaciers are melting, the Arctic icecap is shrinking, and sea levels are slowly rising not only from fresh meltwater but from the expansion caused by higher sea temperatures. The consequences of continued warming are also more uncertain than many in the press would have you believe. For example, continued warming means continued higher rates of evaporation. Some computer models project this evaporation will create more high ice crystal clouds, which would continue to allow plenty solar radiation in for heating. Other models, however, project this evaporation will produce more low and mid level water vapor clouds. No one is certain which scenario is more likely.
Another great uncertainty is what regional effects might be experienced over different parts of the globe. Even during warm phases of global climate, not everyone gets warm. The jetstream winds (multiple bands of steering currents) do not move on a flat west-to-east path in the northern hemisphere (or vice versa in the southern hemisphere). These winds move in waves, with ridges that extend toward the poles and other waves which extend latitudinally toward the equator. So, while global AVERAGE temperatures may continue to increase, some parts of the world will be at the bottom of these latitudinal waves, where colder air from near the poles is delivered. Paleoclimatologists--the scientists who dig up past sediments and ice cores--have found this to be the case during past warmings (which occurred with no help from mankind). A recent example of this--probably not related to climate change--occurred this past winter. While the lower 48 states experienced the warmest January on record, eastern Europe suffered through a death-dealing period of horrendous cold and snow, with high rates of weather-related mortality during the same month.
And here's something else those paleoclimatologists have found: past evidence of incredibly fast changes in climate in Europe and eastern North America. One mechanism may be set off by a continued rapid shrinking of the Arctic icecap, dumping greater amounts of fresh water into the normally very salty North Atlantic. It is this very salty water which sinks, due to its greater density, and then drifts in a great conveyor current toward the Carribean and the Gulf of Mexico, where it heats, rises, and flows northeastward as the famous Gulf Stream current. The significance of this current can't be overestimated. If you look at a map, you'll see New York City is on about the same latitude as Rome. Without the moderating effects of the Gulf Stream, London, Paris, Berlin, Oslo, Stockholm and their surroundings would have long, brutal winters and short, difficult growing seasons. There would be no great vineyards in France, no fields of grain in Holland and Belgium, and a probable decline in the standard of living for western and northern Europeans, as well as for the NE U.S. and the Canadian Maritime provinces. The renowned Woods Hole Oceanographic Institute in New England has been monitoring the salinity of the North Atlantic for some decades, and they report a significant dilution of that salinity. Their paleoclimatologists have found sediments which suggest that once the North Atlantic salinity is diluted to a certain, still unknown threshold, the Gulf Stream can essentially shut down in less than a decade. The irony in all this, of course, is that dilution leading to regional cooling, increased glaciation, and change of climate zones in a densely populated part of the world would be caused by global warming. While global average temperatures would continue to rise away from this Gulf Stream shutdown, that rise would do no good for the hundreds of millions whose lives would be impacted by their extreme regional cooling.
There are other great uncertainties tied to continued warming. Most models project the greatest warming would occur in northern interior sections of North America and Eurasia, with the least warming occurring in the already sultry tropics. There may be increased desertification of parts of America's "bread basket" plains, while the more temperate climate zone would migrate poleward to the northern Canadian prairies, where soil is far less fertile. There is also some potential for nature to produce a feedback mechanism to absorb extra carbon from the atmosphere (small shelled creatures whose shells contain high amounts of carbon), as well as some limited ability of the ocean to absorb some of the excess carbon dioxide. So far, confidence is increasing that most consequences of global warming will cause disruptions for humanity, with northward and southward migration of tropical diseases from the equatorial zone also thrown in the mix.
A discouraging note: carbon dioxide is a long-lived gas in the atmosphere. If we had a miraculous agreement among the industrialized nations of the world to immediately reduce our emissions of greenhouse gasses, the ball is already rolling and will be slow to come to a halt--perhaps more than a century. Moreover, the science of the Kyoto Accords is fairly strong, but the politics are questionable. If India and China are to be treated as developing, third-world nations in this accord (as they currently are), the accord is doomed to failure from the start. China will surpass the U.S. in fossil fuel usage in just a couple of decades, at the most. India will not be far behind. While such a separate status for these 2 growing industrial giants may seem wise in terms of social justice, the math and science is already done. Carbon dioxide emissions will continue to rise at a rapid rate if special exclusions are granted these two most populous nations.
So, no, I won't be touching much on global warming during weather segments anytime soon. I've barely scratched the surface here. The cliché applies: most things ARE more complicated than they first appear to the eye and mind.
Don Paul is Chief Meteorologist at WIVB-TV in Buffalo, NY. He holds the American Meteorological Society Seal of Approval for Television Weathercasting, and has served as a Member of the AMS Board on Broadcast Meteorology.
Short answer: It's too complicated. But for all you scientific minds out there: here is a brief synopsis:
Many of us do chat about global warming at public forums, club meetings, and the like, but 3 minutes on the air is no place to broach such a sea of topics-within-a-topic. What we can say with a high degree of confidence is that global warming is real and appears to be accelerating. It's also very likely that human activity, particularly the burning of fossil fuels, is a significant contributor in the increased levels of carbon dioxide in the atmosphere. What is less certain is HOW significant our role is; it's very difficult to quantify our place in this increase and manmade greenhouse gasses total impact versus other natural processes which may or may not be going on; there are some physicists who claim variations in solar radiation input and the wobble in the earth's orbit may also contribute to warming, as well as gas emissions from volcanic activity. But it's fair to say most meteorologists, climatologists, physicists and atmospheric chemists think we play a large part in this warming.
The evidence of the warming itself is nearly incontrovertible. Most glaciers are melting, the Arctic icecap is shrinking, and sea levels are slowly rising not only from fresh meltwater but from the expansion caused by higher sea temperatures. The consequences of continued warming are also more uncertain than many in the press would have you believe. For example, continued warming means continued higher rates of evaporation. Some computer models project this evaporation will create more high ice crystal clouds, which would continue to allow plenty solar radiation in for heating. Other models, however, project this evaporation will produce more low and mid level water vapor clouds. No one is certain which scenario is more likely.
Another great uncertainty is what regional effects might be experienced over different parts of the globe. Even during warm phases of global climate, not everyone gets warm. The jetstream winds (multiple bands of steering currents) do not move on a flat west-to-east path in the northern hemisphere (or vice versa in the southern hemisphere). These winds move in waves, with ridges that extend toward the poles and other waves which extend latitudinally toward the equator. So, while global AVERAGE temperatures may continue to increase, some parts of the world will be at the bottom of these latitudinal waves, where colder air from near the poles is delivered. Paleoclimatologists--the scientists who dig up past sediments and ice cores--have found this to be the case during past warmings (which occurred with no help from mankind). A recent example of this--probably not related to climate change--occurred this past winter. While the lower 48 states experienced the warmest January on record, eastern Europe suffered through a death-dealing period of horrendous cold and snow, with high rates of weather-related mortality during the same month.
And here's something else those paleoclimatologists have found: past evidence of incredibly fast changes in climate in Europe and eastern North America. One mechanism may be set off by a continued rapid shrinking of the Arctic icecap, dumping greater amounts of fresh water into the normally very salty North Atlantic. It is this very salty water which sinks, due to its greater density, and then drifts in a great conveyor current toward the Carribean and the Gulf of Mexico, where it heats, rises, and flows northeastward as the famous Gulf Stream current. The significance of this current can't be overestimated. If you look at a map, you'll see New York City is on about the same latitude as Rome. Without the moderating effects of the Gulf Stream, London, Paris, Berlin, Oslo, Stockholm and their surroundings would have long, brutal winters and short, difficult growing seasons. There would be no great vineyards in France, no fields of grain in Holland and Belgium, and a probable decline in the standard of living for western and northern Europeans, as well as for the NE U.S. and the Canadian Maritime provinces. The renowned Woods Hole Oceanographic Institute in New England has been monitoring the salinity of the North Atlantic for some decades, and they report a significant dilution of that salinity. Their paleoclimatologists have found sediments which suggest that once the North Atlantic salinity is diluted to a certain, still unknown threshold, the Gulf Stream can essentially shut down in less than a decade. The irony in all this, of course, is that dilution leading to regional cooling, increased glaciation, and change of climate zones in a densely populated part of the world would be caused by global warming. While global average temperatures would continue to rise away from this Gulf Stream shutdown, that rise would do no good for the hundreds of millions whose lives would be impacted by their extreme regional cooling.
There are other great uncertainties tied to continued warming. Most models project the greatest warming would occur in northern interior sections of North America and Eurasia, with the least warming occurring in the already sultry tropics. There may be increased desertification of parts of America's "bread basket" plains, while the more temperate climate zone would migrate poleward to the northern Canadian prairies, where soil is far less fertile. There is also some potential for nature to produce a feedback mechanism to absorb extra carbon from the atmosphere (small shelled creatures whose shells contain high amounts of carbon), as well as some limited ability of the ocean to absorb some of the excess carbon dioxide. So far, confidence is increasing that most consequences of global warming will cause disruptions for humanity, with northward and southward migration of tropical diseases from the equatorial zone also thrown in the mix.
A discouraging note: carbon dioxide is a long-lived gas in the atmosphere. If we had a miraculous agreement among the industrialized nations of the world to immediately reduce our emissions of greenhouse gasses, the ball is already rolling and will be slow to come to a halt--perhaps more than a century. Moreover, the science of the Kyoto Accords is fairly strong, but the politics are questionable. If India and China are to be treated as developing, third-world nations in this accord (as they currently are), the accord is doomed to failure from the start. China will surpass the U.S. in fossil fuel usage in just a couple of decades, at the most. India will not be far behind. While such a separate status for these 2 growing industrial giants may seem wise in terms of social justice, the math and science is already done. Carbon dioxide emissions will continue to rise at a rapid rate if special exclusions are granted these two most populous nations.
So, no, I won't be touching much on global warming during weather segments anytime soon. I've barely scratched the surface here. The cliché applies: most things ARE more complicated than they first appear to the eye and mind.
Don Paul is Chief Meteorologist at WIVB-TV in Buffalo, NY. He holds the American Meteorological Society Seal of Approval for Television Weathercasting, and has served as a Member of the AMS Board on Broadcast Meteorology.
