It’s geography awareness week!

Geography touches every aspect of our lives. At its simplist, geography is concerned with where something is at, why it’s there, and how it relates to things around it. Geography influences where we live, affects our economic prosperity, has dictated the outcome of significant historical events, and shapes our local, regional, and global relationships with each other. Check out this Google Earth overlay of  geography on the job.

Many of the posts here at “The Physical Environment” blog are strictly related to the natural environment. But obviously, humans are directly impact and are impacted by processes that shape the physical environment. The United Nations Environment Programme has created eight short videos exploring the human cost of climate change in Africa. These include Harvesting Rain, Escaping Floods, Creeping Deserts, Mountain Drought among others. Visit the site to watch these videos online.

An invasion is taking place in the United States, and the authorities are worried. It’s not an invasion by a foreign country but from a foreign country. I’m talking about an invasion of giant snakes. It’s not a “purposeful invasion”, at least from the snake’s point of view. That is, these snakes aren’t swimming the oceans to the shores of the United States. Humans are at the heart of this invasion.

Burmese Python (Courtesy USGS)

The problem started back in the 1990’s when some thought it cool to make pythons and boa constrictors imported from Southeast Asia household pets. One of the most popular, the Burmese python, can grow to 6 m (20 ft) and weigh as much as 113 kg (250 lb). Many who purchased the snakes soon found that these creatures require large spaces to live, have rather expensive food requirements, and can be dangerous. Without many agencies willing to accept them, disillusioned owners simply dumped them in the wild. A mistake, a big mistake. Florida estimates that there are over 100,000 large snakes slithering, not only through swampy wetlands, but increasingly turning up in suburban areas of South Florida.

The United States Geological Survey recently released the report, “Giant Constrictors: Profiles and an Establishment Risk Assessment for Nine Large Species of Pythons, Anacondas, and the Boa Constrictor.” Their conclusion was that high risk’ species like “Burmese pythons, northern and southern African pythons, boa constrictors and yellow anacondas—put larger portions of the U.S. mainland at risk, constitute a greater ecological threat, or are more common in trade and commerce. Medium-risk species—reticulated python, Deschauensee’s anaconda, green anaconda and Beni Anaconda—constitute lesser threats in these areas, but still are potentially serious threats.” ¹ Breeding populations of Burmese python and boa constrictor have been confirmed in South Florida, and there is evidence that the northern African python is breeding in the wild as well. The world’s longest snake, the reticulated python reaching 8.7 m (28 feet) and the heaviest, the green anaconda, weighing 227 kg (550 pounds) have both been found in the wild of South Florida although breeding populations have not yet been confirmed.

These snakes possess several characteristics that make them a special threat to Florida ecosystems. They:

“1. Grow rapidly to a large size (some individuals of these species surpass 20 ft in length and 200 lbs in weight);
2. Are habitat generalists (they can live in many kinds of habitats and have behaviors that allow them to escape freezing temperatures);
3. Are dietary generalists (can eat a variety of mammals, bird, and reptiles);
4. Are arboreal (tree-living) when young, which puts birds and arboreal mammals such as squirrels and bats at risk and provide another avenue for quick dispersal of the snakes;
5. Are tolerant of urbanization (can live in urban/suburban areas);
6. Are well-concealed “sit-and-wait” predators (difficult to detect, difficult to trap due to infrequent movements between hiding places);
7. Mature rapidly and produce many offspring (females can store sperm and fertilize their eggs—which in some of these snakes can number more than 100—when conditions are favorable for bearing young);
8. Achieve high population densities (greater impact on native wildlife); and
9. Serve as potential hosts for parasites and diseases of economic and human health significance.” ²

Reticulated Python (Courtesy WikiCommons)

Scientists are concerned that introduced constrictors have the potential to upset food webs by eliminating or depleting native species. Giant constrictors are capable of eating almost any kind of land-dwelling vertebrate or mammal. This is particularly problematic for species that are already endangered, most likely from habitat loss or competition from other introduced species. These snakes pose minimal risk to humans in the wild, only a few unprovoked attacks occur per year worldwide. Reticulated pythons are most associated with known unprovoked fatalities in the wild. Though rare, Burmese and African pythons are also known to attack. All known fatalities in the United States are from captive snakes, usually when the owner is interacting with it.²

Potential range under current climate (Courtesy USGS)

Potential Range by 2100 from global warming (Courtesy USGS)

The Burmese Python is particularly troublesome because much of the southeastern United States has a similar climate to its natural habitat. In another study,  USGS mapped the potential range for this snake, and an alarming pattern was revealed. Though several factors such as type of food and suitable shelter play a role, the maps show where climate alone would not limit the python. Two maps were produced by the study, one showing the current areas where the climate is similar to that of the snake’s native ranges. The second projects the range based on “climate matches” from climate models near the end of the century. Climate changes brought on by global warming dramatically increases the range of the giant snakes.

Efforts are now underway to address the “invasion”.  Local and state ordinances are restricting ownership and requiring owner licensing and snake tagging. An eradication program is underway, but the snakes prolific breeding  in the wild is making it an extremely difficult task.

For more information about this growing problem, see:

• Giant Constrictors: Profiles and an Establishment Risk Assessment for Nine Large Species of Pythons, Anacondas, and the Boa Constrictor (USGS)
• What Parts of the US Mainland Are Climatically Suitable for Invasive Alien Pythons Spreading from Everglades National Park (USGS)
• Watch a constrictor capture.

References for this post:

1. Report Documents the Risks of Giant Invasive Snakes in the U.S. (USGS)
2. Giant Constrictor Risk Assessment: Frequently Asked Questions (USGS)
3. USGS Maps Show Potential Non-Native Habitat Along Three U.S. Coasts
4. Reticulated Python (WikiPedia)

There are two types of feedbacks, positive feedbacks that drive system change and negative feedbacks that seek to keep systems in a state of equilibrium. Geoscientists like physical geographers are recognizing that positive feedback mechanisms may drive the Earth system past thresholds and towards a new state of equilibrium. In so doing, a new physical geography of the Earth system will appear. The
distribution of Earth’s regional climate’s and ecosystems may be irreversibly altered.

Examples of Feedbacks Driving Global Warming

Rising temperatures are expected to cause increased evaporation of water into
the atmosphere, most of which will originate from oceans. The additional water
vapor boosts the absorption of infrared radiation emitted by the earth
resulting in more warming (a positive feedback). The increased warmth promotes
more evaporation yielding an enhanced greenhouse effect. However, the addition
of water may cause an increase in cloud cover resulting in a higher
atmospheric albedo and reflection of incoming solar radiation. If this were to
occur, the reduction in insolation would lead to cooling. Such contradictory
consequences makes it difficult to determine what actually will occur in the future.

Figure 1. Tropical forest – climate change feedback Courtesy NASA
(Source )

Throughout history, humans have cut forests to build structures, warm their
homes, and cook their meals, and clear the land for agriculture. Removing
forests removes a powerful sink for carbon dioxide.  Leaving more CO² in
the atmosphere enhances global warming and thus an increase in temperatures.
As a result, temperature conditions that may be too warm to support healthy
forest ecosystems. With less vegetation present, more carbon dioxide is left
in the atmosphere causing more warming, another positive feedback driving the
earth system toward ever warmer conditions. As temperatures increase,
evaporation increases causing drier conditions and the threat of wildfires and
forest destruction.

Figure 2. Permafrost – Climate change feedback. Image Courtesy USGS

Geoscientists agree that the Arctic has been and will continue to be
significantly impacted by global warming. Much of the land surface in the
Arctic is underlain by permanently frozen ground called “permafrost”.
They uppermost “active layer” experiences seasonal thawing. Recent studies
indicate that climatic warming my result in in a 12 to 15% reduction in the area covered by permafrost and a 15 to 30% increases in the thickness of the active layer.  As temperature rises permafrost melts, releasing stored carbon, but just as importantly, methane.  Increased warming results in more permafrost melting pushing the earth system ever forward into a future enhanced greenhouse environment.

Changes in Arctic ecosystems has already occurred as a result of global warming. Figures 3 a & b shows two photographs from the same location in Alaska, showing the transition from tundra to wetlands over the last twenty years. When permafrost melts, water collects in small  ponds on the surface increasing the heat gain nearly ten-fold. The additional heat continues to melt the underlying permafrost causing it to collapse and increasing the size of the pond. This positive feedback further degrades the permafrost.

Carbon dioxide makes up a greater proportion of  the atmosphere by volume, but methane absorbs energy much more efficiently. Increased warming at high latitudes may cause an increase in the
release of methane from bogs or peatlands. Methane release from organic decomposition in wetlands coupled with carbon dioxide from melting permafrost will drive greenhouse gas levels higher, creating warmer temperatures.

Figure 4. Sea Ice – climate change feedback
Image Courtesy USGS
Changes to the reflectivity of the surface (called the albedo) affects the amount of solar radiation absorb by the Earth. As Arctic sea ice melts it exposes open water which is less reflective (albedo decreases). The reduction in albedo allows more light to be absorbed by the ocean. As the ocean water warms, more heat is added to the air creating a positive feedback and driving Arctic temperatures ever higher. The reduction in sea ice is having a significant impact on arctic ecosystems.

Tipping Points

Positive feedbacks drive the physical environment towards new physical states. In June of 2008, twenty years after his landmark testimony about global warming, Dr. James Hansen reiterated his warnings before the U.S. Congress. He cited several examples of earth systems reaching or nearing a tipping point. A tipping level (point) is a level at which “no additional  forcing is required for large climate change and impacts.” (Hansen, 2008).  According to Hansen, a  “point of no return” is reached when unstoppable and irreversible (on a practical time scale) occurs. The disintegration of the Greenland ice cap is an example.

Time is also an important factor in assessing whether a tipping point has been reached or a point of no return. Some, like Josefino Comiso of the NASA Goddard Space Flight Center,  feel that the tipping point for perennial Arctic sea ice has already passed (National Geographic, 2007). David Barber, of the University of Manitoba is projecting that the North Pole will be ice free for the first time in history. For example, sea ice may completely disappear from the Arctic Ocean during the summer in a few years. This would represent a new state for the Arctic ocean. But temperature conditions could change in the relatively near future to permit sea ice to reform during the summer.

[Adapted from "Future Geographies: Feedbacks Driving Global Warming". The Physical Environment: an Introduction to Physical Geography.]

Environmental Change and Global Warming

During the summer of 2005, the United States was pounded by a record number of hurricanes, some the most intense to ever strike the mainland. The southwest desert of the United States continues in the grip of one of the longest periods of drought. For the first time in centuries, the fabled arctic northern route is open between North America and Asia. Are these events caused by climate change due to global warming? If so, the future physical geography of planet Earth may be drastically and irreversibly changed if current global warming predictions are realized.

Figure 1. Major Components needed to understand the climate systems and climate change. (Source: US Climate Change Science Program).

Environmental change caused by global warming involves a complex set of interactions between the subsystems of the earth system and human activities. These interactions vary across geographic scales. The timing and impact of future warming will not be the same for all regions of the Earth. Research methodologies that consider place and scale are therefore essential in understanding future environmental changes.

Figure 2. Schematic Framework of anthropogenic climate change drivers, impacts, and responses. Courtesy IPCC

The continuum of geography permits a holistic view of earth systems analysis. Geographers are therefore perfectly positioned to answer questions concerning global warming and environmental change. Geographers are engaged in all aspects of environmental change research, from field monitoring glacier movements to computer modeling of future climates. Straddling both social and physical sciences, geographers play an important role in unwinding the social and economic drivers behind climate change.

Observing environmental change

Geographers bring their unique talents to recording changes in earth systems. Geographical positioning systems (GPS) provide precise measurements of environmental change. For example, isostatic rebound of the earth’s surface after the last ice age complicates measurements of melt from the expansive ice sheets that cover present-day Greenland and Antarctica. Recently, several GPS stations were deployed around the Greenland ice sheet to measure minute changes in earth surface elevation as a result of rebound. This data is being combined with that from sensors measuring elevation changes, glacial outflow rates and the mass balance to provide a more complete assessment of the sheets’ melting.

Figure 3. A one-meter tall station (above) was installed last Thursday near Ilulissat to measure how much the earth’s crust rebounds as the ice sheet melts. Courtesy Thomas Nylen (UNAVCO) Source

Databases for analyzing the effects of climate change are large and complex. As databases documenting environmental changes across the earth are developed, geographers will provide the tools for teasing out spatial and temporal signals in the observations. Geographic Information Systems are well-suited for handling complex databases to map the potential spread of diseases, ecosystem changes, and sea-level rise as a result of global warming.

Analyzing environmental change

Geographer’s have a number of tools and skills to analyze the impact of environmental change on earth systems. Geographers are actively engaged in projects to identify and understand patterns of deforestation and habitat fragmentation. Geographer Eric Larsen has studied the decline of aspen trees in Yellowstone for several years. Though climate change was first suspected, he and ecologist William Ripple, realized that aspens outside the park flourished. If climate change was responsible, trees inside and outside the park would have suffered a decline. Analyzing cores from trees within the park, they found that most were 70 years old, aspens had apparently stopped regenerating around the 1930s

Figure 4. Reintroduced wolf in Yellowstone Park. Courtesy NPS.

Between the late 1880s until the mid-1900s, more than bounty hunters killed 100,000 wolves in Wyoming and Montana. By the 1970s, the wolf was classified as an endangered species. A controversial reintroduction program brought 31 gray wolves back to the Yellowstone ecosystem. It appears that the removal of a top predator, allowed browsing elk populations to flourish and devastate young aspens. With the reintroduction, diversity and stability of the ecosystem appears to be on the rise.

Explaining environmental change

Geographers can play a significant role in hypothesis and theory development. Geographers are particularly suited for building numerical models of the complex coupling between the earth’s surface and atmosphere above. Their strong field orientation and integrated methods will help hone the parametrization of climate models.

Figure 5.  Comparison between modeled and observed temperature rise without human factors, with human factors and both. Courtesy IPCC

Geography’s human-environment tradition provides a foundation for answering some of the most vexing issues of the global warming.
The crux of the global warming issue is identifying the “fingerprint” of human activities in creating the enhanced greenhouse effect. For example, models that attempt to explain the warming experienced over the last several decades using only natural factors fail to adequately explain the actual pattern temperature. When human factors that influence warming are added, a much better correspondence with reality is uncovered.

Because geography uniquely straddles both physical and social sciences, geographers play an important role will play a role in future policy formulation and decision making. Geographers are well-suited for evaluating the costs and benefits of various global warming mitigation strategies.

Predicting environmental change

Climate models have demonstrated that the impact of global warming will vary across the earth. Geographers have been at the forefront of predicting the potential changes that our environment will undergo. Based on recent analyses, Geographer Jack Williams found that, we’re headed for major change — fast. He suggests areas that currently have a tropical climate will become warmer, pushing vegetation and animal life northward. Williams believes these changes will lead to the spread of insect-borne diseases like Malaria, increased catastrophic natural disasters and greater risks to human well-being. Temperatures rising just a few degrees will affect where particular plant and animal species will thrive. The question is if they will be able to migrate or adapt to a rapidly changing climate. If not, some face extinction.

Williams work predicts that many current climates may entirely vanish by the year 2100. He foresees “no-analog” communities of plants and animals arising from “novel” climates. No-analog communities consist of species that exist today but in differ net combinations from those presently inhabiting the earth. The species exist today, they have just been “reshuffled” into new combinations not found at the present. Such no-analog combinations have been found recorded in fossil pollen assemblages extracted from lake sediments dating from the late-glacial periods in North America. These seemingly odd past combinations of species are thought to be a product of of “novel” or no-analog climates, characterized by
higher-than-present temperature seasonality. Professor Williams recognizes that with current trends in global warming, such new communities of species may be in our future. His climate models project the disappearance of many existing climates in tropical highlands and near the poles. Large swaths of the tropics and subtropics may develop new climates unlike anything seen today.

[Extracted from "Future Geographies: The Geographer’s Role in Understanding Environmental Change“. The Physical Environment: An Introduction to Physical Geography

As photographer James Balog with the Extreme Ice Survey states in this July 2009 TED Talks, “Ice is the canary in the global coal mine”. Watch his talk as he provides some of the most astounding visual evidence of global climate change.

James Balog and the Extreme Ice Survey were featured in a one-hour documentary on NOVA/PBS on March 24, 2009. You can watch the program online at NOVA/PBS.

View a Google Earth overlay with photos and time-lapse videos here

The Physical Environment link -> Climate Change: Global Warming, Evidence from Glaciers

Antarctic ozone hole, August 23, 2009. Courtesy NASA.

For decades a “hole” in the ozone layer opens over the Antarctic each year. Harmful levels of UV light can make their way toward the Earth’s surface impacting ecosystems in the far Southern Hemisphere. You can follow the rapid opening and gradual closing of the hole at NASA’s “Ozone Hole Watch“. Here you’ll find recent high resolution images, daily and monthly average animations and graphs showing the progress of this year’s ozone hole.

The Physical Environment link: The Stratosphere

NASA’s Wayne Esaias sees honeybees as important data collectors to help us understand our changing climate.

Bob Edwards talks with environmental scientist James Lovelock about his latest book The Vanishing Face of Gaia. Lovelock argues that it’s already far too late to stop global warming, and that we should be committing our resources to surviving in the new hotter world to come instead of trying to stop it.

http://podcast.com/episode/41520365/32910/

The Physical Environment Link: Natural Systems, Greenhouse Effect & Global Warming

Shark Alert! Species Struggle

Courtesy National Geographic