Ecosystems in a changing climate

2007-11-30

in Science, The environment

Ashley Thorvaldson in party mode

As climate changes, many species are moving. Sometimes, it is from lower to higher altitudes, in order to live in familiar temperatures. Sometimes, it is from south to north for the same reason. Such natural adaptation is inevitable and, while it is a coping mechanism for individual species, it invariably changes the composition of ecosystem. Birds and flying insects may be able to relocate more easily, leaving slower-moving or less adaptable species behind. Suddenly, the structure of food webs start to change as predator-prey relations are redefined.

Some people have argued that allowing ecosystems to respond to climate change on their own is the best course of action. Others have argued that vulnerable species should be relocated to areas where they will be able to continue living. Some have even argued that polar bears should be relocated to Antarctica to make them less vulnerable to global warming. Others have argued that elephants and rhinos should be introduced to North America as a hedge against the danger of poaching. Finally, there are those who argue that we should actively manage ecosystems to try to mitigate climate change effects: if pests have shifted into new areas and begun eating crops, import their predators. If coastal erosion is worsening, bring in species to stabilize beaches.

The human record of such interventions is definitely not stellar, but the debate is nonetheless increasingly energetic. The discussion is both pragmatic – asking what the probable costs and benefits of making a change would be – and philosophical – engaging with the question of what the ‘natural’ world is and how people should engage with it. Global climatic change will make both of these sets of questions more immediately relevant and pressing.

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Milan November 29, 2007 at 2:55 pm

State of the Wild: Perspective of a Climatologist (PDF)

10 April 2007

Jim Hansen
Introduction. “Animals are on the run. Plants are migrating too.” When I wrote those words in 20061, I was trying to draw attention to the fact that climate change is underway. People do not notice climate change readily, because it is masked by large day-to-day weather fluctuations, and we reside in comfortable homes and offices.

Anon November 30, 2007 at 11:41 am

A man invents an aorist rod to mine energy from the past, and within a year tracts of the past were being fully drained. Those who complained were accused of an “extremely expensive form of sentimentality”, as the past was a cheap, clean and plentiful source of energy. Anyone who said “draining the past impoverished the present” was told to “keep a sense of proportion”.

Only when the people realised that the “selfish plundering wastrel bastards up in the future” were doing the same thing to their era were aorist rods banned. “They claimed it was for the sake of their grandparents and grandchildren, but it was of course for the sake of their grandparent’s grandchildren, and their grandchildren’s grandparents.”

. November 30, 2007 at 3:42 pm

Iron In Oceans Not A Solution For Global Warming, Says Research

Fertilizing the ocean with iron or other nutrients to cause large algal blooms, has been proposed as a possible solution to global warming because the growing algae absorb carbon dioxide but research performed at Stanford and Oregon State Universities and published in the Journal of Geophysical Research suggests that ocean fertilization may not be an effective method of reducing carbon dioxide in the atmosphere.

Milan December 2, 2007 at 4:03 pm

Federal government’s own policies could harm ecosystems

The Harper government is opening the door to “wide-ranging” and “large scale” impacts to the earth’s ecosystems because of its refusal to recognize a tipping point in the battle against global warming as it heads into major United Nations climate change summit that begins on Monday, warns a newly-released federal document.

Foreign Affairs officials who prepared the internal research paper suggested that the government could improve its environmental policies if it recognized the dangers associated with allowing human activity to contribute to warming the planet’s average temperature by more than two degrees Celsius.

“The scientific uncertainty surrounding the temperature increase thresholds that would trigger global scale impacts (i.e., slowing of the North Atlantic Ocean currents, collapse of Greenland and/or West Antarctic ice sheets), highlights the merits of a precautionary approach,” reads the document that was released to the Pembina Institute following an access to information request. “Some recent studies suggest that these wide-reaching, large-scale impacts could be triggered by a temperature increase as low as one degree Celsius (to) two degrees Celsius from pre-industrial levels.”

Anon December 3, 2007 at 2:44 pm

Nature Reports Climate Change
Published online: 23 November 2007 | doi:10.1038/climate.2007.70

The escalator effect

Emma Marris

Rising temperatures are changing mountain ecosystems as the heat forces some species upwards — until there is nowhere left to go. Emma Marris reports on the ‘escalator effect’, which is threatening species worldwide.

“We were quite shocked by how dramatic these changes have been,” says Wilson, who is now at the University of Exeter. “I feel very privileged to have seen those species and habitats while many of them are still here.”

The biological world is changing because of global warming. Most non-specialists are familiar with poleward shifts — migration routes and species distributions that are creeping north in the Northern Hemisphere and south in the Southern Hemisphere as the equator-facing edges of these historic ranges become too hot for species to handle.

The same phenomenon is happening in three dimensions, though there is less data and less media coverage for these upward trends. As the climate warms, there is a corresponding increase in temperature at any given elevation. And any species unable to take the heat — or related changes in, for example, precipitation — will generally move up the mountain towards colder climes, until they reach the top.

Anon December 3, 2007 at 2:47 pm

Complicating the picture is the observation that not all species adjust to temperature shifts at the same rate. Bird species may flee uncomfortably hot altitudes far before a tree-line shifts uphill. And many species may move not because they can’t take the temperatures themselves, but because of the impact of climate change on other species they rely on, or because the creeping heat favours pathogens that kill them off.

“I am most concerned about species’ communities being torn apart,” says Stanford ecologist Terry Root. “It is all going to be quite a mishmash of things.”

. December 4, 2007 at 11:08 am

‘Tropics expand’ as world warms

In Science/Nature

The tropical belt has become wider in recent decades, with climate change the probable cause, research suggests.

. December 20, 2007 at 3:55 pm

Darwin never imagined that the effects of climate change could be observed in a human lifetime, yet, almost anywhere you go in the world today, it is possible to observe changes comparable to the northern expansion of the comma [a butterfly]. A recent study of common frogs living near Ithaca, New York, for example, found that four out of six species were calling, which is to say mating, at least ten days earlier than at the start of the nineteen-hundreds, while at the Arnold Arboretum, in Boston, the peak blooming date for spring-flowering shrumbs has advanced, on average, by eight days. In Costa Rica, birds like the keel-billed toucan, once confined to the lowlands and foothills, have started to nest on mountain slopes; in the Alps, plants like purple saxifrage and Austrian draba have been creeping up toward the summits; and in the Sierra Nevada mountains of California the average Edith’s checker-spot butterfly is now found at an elevation of three hundred feet higher than it was a hundred years ago. To what extent life will be transformed by the warming expected in the coming years is, at this point, still a matter of speculation. Clearly, though, the process has begun.

. December 21, 2007 at 10:35 am

Over the last 30 years, leaves have started to change colour and fall later in the year, a phenomenon that scientists can now attribute directly to rising levels of atmospheric carbon dioxide.

Gail Taylor from the University of Southampton and colleagues studied the growth and leaf fall of Populus trees — a genus which includes aspen and poplars — growing in Tuscania and Wisconsin from 2003 to 2004. The trees were grown in plots under either current or elevated atmospheric carbon dioxide levels and their colour was monitored using remotely sensed images of canopy greenness. Leaves turned yellow later in the year under higher carbon dioxide concentrations, even when exposed to the same temperatures. The researchers think that the change in leaf colour is probably due to the effect of carbon dioxide on plant physiology.

Whereas earlier springtime leaf growth is strongly related to temperature, the belated autumn leaf fall — previously inexplicably — is not. Deciduous trees are staying greener for longer than they were 30 years ago owing to the earlier arrival of new leaves and later leaf falls.

Milan January 16, 2008 at 2:06 pm

The high costs of doing nothing, part III
Climate change disrupts ecosystems that provide valuable services

. September 8, 2009 at 12:54 pm

Google trick tracks extinctions
By Judith Burns
Science and Environment Producer BBC News

Google’s algorithm for ranking web pages can be adapted to determine which species are critical for sustaining ecosystems, say researchers.

According to a paper in PLoS Computational Biology, “PageRank” can be applied to the study of food webs.

These are the complex networks of who eats whom in an ecosystem.

The scientists say their version of PageRank could be a simple way of working out which extinctions would lead to ecosystem collapse.

Every species is embedded in a complex network of relationships with others. So a single extinction can cascade into the loss of seemingly unrelated species.

Investigating when this might happen using more conventional methods is complicated as even in simple ecosystems, the number of combinations exceeds the number of atoms in the universe. So it would be impossible to try them all.

Co-author Dr Stefano Allesina realised he could apply PageRank to the problem when he stumbled across an article in a journal of applied mathematics describing the Google algorithm.

. September 19, 2009 at 4:42 pm

Help wanted to write book of life

A virtual book of all life on Earth is being created by UK and US scientists.

The online reference work will create a detailed world map of flora and fauna and track changes in biodiversity.

The database, dubbed a “macroscopic observatory”, will be populated with data about local species gathered by members of the public.

Early elements of the giant database, such as automatic species identification systems, are already under construction.

. February 22, 2011 at 10:35 pm

Allergy season expands with climate change

Many Canadians with ragweed allergies face nearly an extra month of suffering as the climate warms, a new study shows.

Between 1995 and 2009, the ragweed pollen season grew by 25 days in Winnipeg and 27 days in Saskatoon, according to a paper published this week in Proceedings of the National Academy of Sciences.

Over that 15-year period, other areas of North America above 44 degrees latitude (which runs just south of Madison, Wis.) saw their ragweed pollen seasons expand by at least 13 days, according to the research led by Lewis Ziska at the United States Department of Agriculture in Beltsville, Md.

In general, the ragweed season expanded more at sites farther north.

The study linked the extended season to a delay in the first frost and the longer frost-free period of the year.

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