Bob Ryan on Global Warming, Part 6
Is our climate changing?
By BOB RYAN
Updated 5:33 AM PST, Mon, Mar 9, 2009
Courtesy Polar research Group-University of Illinois at Urbana-Champaign
However while there is general agreement in the observations that the extent of Arctic sea ice is decreasing in summer and the annual average extent of Arctic sea ice is also decreasing, the average coverage of Antarctic (South Pole region) ice is increasing a bit. How can this be?
On any day, the total sea ice in the Arctic and Antarctic regions covers an area about the size of the United States. A critical difference between the climate of the North and South Poles is that the North Polar Region is primarily an ocean, the Arctic Ocean, and the southern polar region is one of Earth’s great landmasses, the Antarctic continent.
(By the way, imagine what our climate, ocean level and landmasses would look like if Antarctica was in the South Pacific rather than the South Pole.)
The increases and decreases in glaciers and sea ice are not only driven by global or polar warming and cooling, but also changes in precipitation. Recent scientific studies suggest that increasing precipitation in the southern polar region is increasing the thickness of Antarctic glaciers and sea ice. The precipitation/snowfall pattern across the great Antarctic continent is also complex, with some regions experiencing increased snow and glacier depth, while other regions are showing decreasing glacier thickness.
As I have often mentioned and shown, the earth is a “dynamic” system and even the ice-covered poles are “dynamic.” And while we observe the dynamics of ice, snow and glaciers in a warming world, here is an example of what appears to be a dramatic example of global warming -- the declining snowcap of Mt. Kilimanjaro. However, I think Mt. Kilimanjaro is an even more dramatic example of the wider and perhaps more important topic of global change.
The fabled “Snows of Kilimanjaro” as seen in 1993 and recently. A rapidly shrinking glacier often used as an example of the dramatic effects of global warming:
Kilimanjaro February 1993 and February 2000 (below) Courtesy NASA
A number of recent studies by scientists have shown that this tropical glacier has different causes for its shrinkage than global warming alone. Deforestation across central Africa (certainly “global change” but not global warming) reduced moisture entering the atmosphere from forests and reduced moisture rising in westerly winds up Kilimanjaro, thus reducing snowfall on the glacier.
With reduced moisture and the strong equatorial sun at the high altitudes, the ice and snow is disappearing by “sublimation.” The ice is not melting ... it is changing directly from ice water to water vapor and into the atmosphere. Thus some of the loss of “The Snows of Kilimanjaro” is probably due to human global impacts -- deforestation of large areas -- but not a direct result of increasing greenhouse gases. Not everything may be as simple as it first appears ... in science as in life.
How Can It Be Warming When I’m Freezing?
I know as I write this near the end of winter, many areas in the eastern U.S. and Europe have seen a very cold winter with record amounts of snow and storms. You’re thinking, “How come I’m freezing if 'global warming' is really happening? It can’t be!”
But look at this.
This shows the temperature “anomaly,” or departure from average, on a day when news headlines were of extreme cold in the East. Yet look at the above average mid-winter warmth across much of the high Arctic, Siberia, Greenland, northern Canada and Alaska where only weeks earlier temperatures were 40° below zero. A relatively mild mid-winter day in Siberia doesn’t get many headlines. Simple news headlines usually don’t mean simple science.
Theories, Science, Advances and Understanding
The theory of anthropogenic global warming is just that -- a theory that will continue to be tested by scientists for years to come.
There is a difference between what scientists think of as “theory” and what you may think is a theory. Certainly, there are many areas of climate change that are still not well understood, such as we’ve seen with pollution and haze. The correct modeling of clouds and changes in the reflectivity of earth in a world with increasing carbon dioxide (but also man-made hazes and particulate pollution as we observed over China) is still not completely understood and is one of the areas needing more work to create ever more accurate global circulation models.
Here is what I think is very important. Almost every area of science, physics, chemistry, medicine, biology, Earth sciences, etc., is moving forward by experimentation and rigorous testing of every “theory.”
We test Newton’s theory of universal gravitation every time we jump in the air ... and come back to Earth. So far, the theory has been verified.
The science, the observations, the theories, the models of global warming and global change are advancing every day. Scientists are better understanding everything from the dynamic glacial changes in Greenland, to the interactions of ocean currents and cycles (think of El Nino and La Nina) and atmospheric patterns, the changes in land and climate in weather (the urban heat island effect), long-term solar climate patterns ... the list goes on and on.
But science advances. Every new experiment and observation by dedicated scientists advances our understanding of the changing weather, climate and Earth. Each idea and theory is undergoing tests; scientists seek to duplicate and confirm, or find errors, in previous results. They look for alternative explanations, test those ideas and theories but as we see in the history of science, slowly converge in the great fundamental questions of science, to common shared theories, assumptions, verifiable observations that confirm the theory over time.
Do these become scientific facts or “laws?” Common belief is these long-verified theories of science are laws and now facts -- just like Newton’s “Law of Universal Gravitation” -- until something comes along to question that.
For Newton’s “Law,” that something has been Einstein’s General Theory of Relativity, nuclear physics, the behavior of nature at incredibly small scales and the development of quantum mechanics early in the 20th century. Suffice it to say Newton would be surprised to find out what happens to his “law” in the world of subatomic particles. But he also would probably love to learn more about these new worlds.
So when you hear the ongoing debate (often by non-scientists) about the science I hope we’ve looked at together, remember that some new finding, observation, model simulation and especially news headline doesn’t necessarily prove or refute anything. It only helps advance our understanding and perhaps even reduces some of the uncertainties of the great scientific issues of global change, climate change and global warming.
However, at the end of the day, the overwhelming evidence and the studies being done by the leading scientists of the world do indicate that children, our grandchildren and we will be living in a warmer world in the future. Warmer by probably 1-5° Fahrenheit within the next 50-100 years.
This does not mean every area will be this much warmer. On the other hand some areas of the globe may be even warmer than +5°. Storm and precipitation patterns are likely to change, producing more water in some areas and less in others.
Current models and studies are getting better and better at realistically projecting more regional and local changes. Changes that are important not necessarily for temperature but with the delicate interrelations of weather and climate systems -- critical things like precipitations, snowpack, biodiversity, water resources, forest ecosystem changes, growing seasons, soil moisture and ice pack.
Indeed, in the years ahead, the impacts of global changes in precipitation patterns may be more important than just changes in the average global temperature. As an example, much of the western United States is dependent on the snowpack of the Rocky Mountains and Sierra for water. What happens if the average winter snows in the west decrease by only 30 percent? What about the sugar maples of New England? What about the Florida coastline? The list goes on and on.
What Should We Do?
At the beginning of this tome I said this would be a journey under the umbrella of science ... my science of meteorology.
I want to keep that promise and hope that what I have done is given you a better understanding of the topics since I do think that climate change and global warming are just part of the larger field of global change that includes everything from land use, species sustainability, economics, air and water quality, food resources and on and on.
Ultimately, we all have to be involved in the decisions; personal, local, regional, political and global, that have been made for years and years and will have to be made in the future. Only by having the best understanding of the issues, and here the science, can we hope to help collectively make the best decisions for ourselves, our children, our grandchildren, our community, country and world in the critical years ahead.
I hope I have helped in some small way.
For more information and some variety of thoughts on the subject and theory and science go here:
http://www.ucar.edu/news/features/climatechange/multimedia.jsp#sciviz
http://www.ucar.edu/news/features/climatechange/faqs.jsp#globalwarming
http://climatesci.org/
http://www.climatescience.gov/
http://dels.nas.edu/climatechange/
http://www.climatescience.gov/default.php
http://climateknowledge.org/figures/Rood_Climate_Change_AOSS480_Documents/Lean_Solar_Variability_Physics_Today_2005.pdf
http://www.ipcc.ch
http://www.nsidc.org/arcticseaicenews/
http://www.usgcrp.gov/usgcrp/default.php
First Published: Feb 27, 2009 1:32 PM PST
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