The annual maple sap flow has begun early in parts of Maine. According to the Bangor Daily News, mild day and night temperatures and a lack of snow is having a strong effect on Maine’s maple syrup industry.  The average start date for sap flow in Maine is March 20, with central Maine beginning March 7-10.

This year, sap flow is already strong in parts of the state, while daytime temperatures are still too low in other areas.  The forecast for this year’s production is unpredictable because of the strange weather patterns.

Sap flow in maples occurs when warm days and cold nights stimulate conversion of starch to sugar, and the osmotic potential created by high sugar concentrations in sap draws water in from the soil.  This creates a positive pressure in the xylem, allowing sap to flow from cuts in the stem.

Global warming is predicted to drive sap production further north, as spring weather warms more quickly.  Average night-time temperatures are increasing throughout New England, and this does not bode well for the long-term prospects for the US maple syrup industry.  However, 2009 was a record year for syrup production in Maine following a disastrous 2008. 

A new atlas of butterfly observations in Britain shows that several southern species are moving north quickly. The atlas, based on 40,000 observations made by a network of volunteers over 10 years shows that species adapted to northern climates are moving north or uphill, while more broadly distributed species are not changing their distribution.

This atlas is an important early sign that species are already adjusting their geographical distribution in response to climate change. These butterflies may be an early warning sign that species and biological communities are under climate pressure, and range adjustments have already begun.  It will be a long time before we see shifts in slower-moving species, including trees.

Observations like these are important because they can improve the ability of biologists to predict the impacts of climate change.  There are not presently enough detailed observations being collected about animal and plant species. Networks of volunteers who can make accurate observations over long periods of time are needed, especially at northern latitudes, where the most rapid range changes are anticipated.

Picture: Citrus swallowtail, Papilio demodocus Esper. Picture by David Cappaert, Michigan State University, Bugwood.org. Used by permission. (This butterfly is not one of the species described in the atlas)

Atlas of butterflies shows southern species head north | Environment | The Observer

An experiment that pumps carbon dioxide into groups of trees growing outdoors, designed to test how forests will respond to global warming may be ended by the US Department of Energy.

This is not a nefarious plot to squash the results of global warming research, but a genuine disagreement among two groups of scientists over how to proceed in climate change research.

The US Department of Energy has funded nearly 10 years of research at Duke Forest in Durham NC, Oak Ridge National Laboratory in Tennessee, and Harshaw Experimental Forest in Wisconsin. At each forest, rings of plastic pipes release carefully measured amounts of CO₂ into the air around groups of trees.  The experiment is known as FACE, for Free Air Carbon dioxide Enrichment.

Results so far indicate that forests respond to the extra carbon dioxide, an essential plant nutrient, by increasing growth. However, unless the forests are on fertile ground, growth is concentrated in short-lived plant parts like leaves or needles and fine roots. These parts die and decompose, releasing their carbon back into the atmosphere. When fertility is higher, trees may retain more of the carbon in wood. However, fertility experiments are not yet complete.

Project scientists believe that a few more years of data are needed to determine the effects of soil fertility on the ability of trees to sequester carbon.  However, DOE scientists believe that the experiment has run its course and that it is time to sample the trees and soils as a final measure of the long-term impacts of the experiment.

Richard Norby, who oversees the experiment at Oak Ridge, said “"This comes up in all sorts of long-term experiments — when is the right time to say, `Enough,’ There’s no good answer to that."

Picture: Duke FACE Experiment, courtesy of Duke University

Sources:

• Duke FACE
• Oak Ridge FACE
• Aspen FACE
• The Associated Press: Gov’t wants to change course of forest experiments

Henry David Thoreau was an acute observer of the plants of Concord, Massachusetts and Walden Pond. He carefully recorded the abundance and phylogeny of plants in the area. Phylogeny refers to the timing of seasonal activities such as flowering.  Thoreau’s data provides information about species abundance and flowering time of the plants of Concord 150 years ago.

Since Thoreau’s time, several botanists have revisited the natural areas around Concord, creating a unique sequence of observations of change in vegetation over time. Charles Willis and colleagues at Harvard and Boston Universities have analyzed Thoreau’s data and those of botanists since his time and analyzed the abundance of the same species in Thoreau’s old neighborhood over time.  Concord is unusual in still having large areas of land undeveloped or protected since Thoreau’s time.

Willis and colleagues analyzed data for 473 plant species and included information on changes in species abundance, habitat, and sensitivity of flowering to temperature.  They also constructed a phylogeny (relationship diagram) for all the species.

The study shows that climate change has had a profound influence on the plants of Thoreau’s woods. Of the plants that existed in Concord in Thoreau’s time, 27% have disappeared, and 36% have decreased in abundance so much that they are likely to disappear soon. Some of the decline is due to forest succession, some to development, but much of the change appears to be due to climate change. The mean annual temperature has increased by 2.4 degrees C in the last 100 years. Plant species are flowering an average of 7 days earlier than in Thoreau’s time.

The species that have disappeared or declined are more likely to be closely related than one would predict from random chance. The authors explain that this is probably due to the similarity in flowering response to temperature among closely related species.

Some plant species can track seasonal temperature change.  These species will flower earlier when temperatures are warmer.  Other species are not as good at tracking temperature, continuing to flower at the same time every year regardless of temperature.  The good trackers increased in abundance or held their own, while the poor trackers were more likely to decline in abundance.  And the poor temperature trackers tended to be related to one another. This means that poor temperature tracking seems to be a trait of certain plant families, but not of others.

The plants most likely to decline were asters, bladderworts, buttercups, dogwoods, lilies, louseworts, mints, orchids, saxifrages and violets.

This study is interesting because of the connection to Thoreau. It is important because it shows that the risk of extinction due to climate change is shared among closely related plants. Species whose flowering times do not change with seasonal temperature changes are more likely to become extinct (globally or locally) than species that do shift their flowering times.  And, the species that don’t change flowering times are likely to be closely related.

Dogwoods (Cornus spp.) are of particular concern because they are declining for other reasons as well.  Dogwoods are suffering since the introduction of the serious disease dogwood anthracnose, caused by the newly identified fungus Discula destructiva, dogwood populations may be uniquely vulnerable to extinction caused by a combination of climate change and disease. 

Links:

• Phylogenetic patterns of species loss in Thoreau’s woods are driven by climate change – news report, PNAS
• C.G. Willis, B Ruhfel, R.B. Primack, A.J. Miller-Rushing, C.C. Davis. 2008 Phylogenetic patterns of species loss in Thoreau’s woods are driven by climate change. PNAS 105: 17029-17032. DOI: 10.1073/pnas. 080656105

The American public has been slow to appreciate the slowly unfolding disaster known as global warming.  Until recently, it was hard to see the impacts of climate change. Not anymore.  In the last couple of years, pictures of melting glaciers, swimming polar bears and storm damage have become common.  It may be that the appearance of these pictures is what has finally shifted public opinion, with large majorities of people in nearly all countries appreciating that climate change is a serious problem.

CNN has a slide show tour of global melting narrated by the renowned photographer Gary Braasch. Braasch’s dramatic photographs, accompanied by a narrative by Bill McKibben, appear in a new book, What Matters, created by David Elliott Cohen.  The book is available as a free download.

Millions of words have been written about global warming, but it is the work of photographers like Braasch and Cohen that shows us the immediacy of the crisis.

Meltdown: A global warming travelogue – CNN.com

Meltdown:  Chapter from What Matters (PDF)

What happens when global warming makes parts of the US uninhabitable, or less attractive as a place to live. It is likely that the southwestern US will become so dry and water so expensive that people will choose to live elsewhere. People currently living along coasts that become inundated by sea level rise and increasingly battered by tropical storms may choose to live further inland. 

Until now, nobody seems to have been seriously addressing the issue of migration in response to climate change, perhaps because it seems so far in the future.  But in fact, migration is already happening: many families displaced by Hurricane Katrina chose not to return to New Orleans, and the same may be true after Hurricane Ike.

In Portland, Oregon, which often seems to think about the future before everyone else, people are now beginning to seriously consider the population impacts of climate change.  Although nobody can make predictions about the potential for migration, it is worth incorporating into planning. Lorna Strickel, a Portland water planner, originally brought the potential for climate-related migration to the attention of planners, mayors and others at a conference. Strickel is particularly concerned about the potential for population growth to stress the city’s water supply.  Since Portland water supply depends heavily on mountain snow pack, a double impact of climate change could be felt – reduced water availability as snow pack is reduced, and increased population.

Regional predictions for Kentucky suggest something similar. In a warmer climate, Kentucky will continue to have good water supplies, with increased precipitation increasing stream flow. However, severe droughts will probably be more frequent.  Kentucky could become more attractive as a place to live because of abundant water, but with increased drought frequency stressing the water supply.  Kentucky needs to begin planning for better water management and storage.

Look out, Oregon, for a global warming land rush – Oregon Environment News, Photos & Videos ­ OregonLive.com

A private company, GreenTrees, is creating long-term contracts with landowners in the Lower Mississippi River Alluvial Valley, including Western Kentucky, to plant forests of cottonwood and other hardwoods. The purpose of the project is to create value through a combination of biomass production for industry and carbon sequestration opportunities. Carbon sequestration will create income streams through trading in carbon cap and trade markets.

In exchange for leasing the land to GreenTrees, landowners receive up-front payments, timber harvest income, recreational income, carbon-based income, and appreciating property values, as well as federal and state conservation incentives and payments.  Landowners can engage in these kinds of activities on their own, but they can’t tap into the up-front income offered by GreenTrees.

The Lower Mississippi River Alluvial Valley was a richly forested region until the 20th century, when bottom-land farming of soybeans cleared vast areas of land.  These lands are in the long run more valuable for carbon storage and watershed protection than crop production.

Stay tuned for more information on this interesting development.

Green-Trees.com

Cross posted at Sustainable Kentucky and Tree Trends.

A very important article from Joe Romm at Climate Progress this morning. Evidence is growing that methane in the atmosphere is increasing, and methane is a powerful greenhouse gas (20 times the heat absorption of CO₂ One source of methane may be deep sea-bed deposits that are released as the Arctic Ocean warms.   Joe points out that the evidence is preliminary until the research is published in a peer-reviewed journal, which is planned.

As a general recommendation, if you are interested in the science and politics of climate change, Joe’s Climate Progress blog is the most reliable source of information available.

Climate Progress » Blog Archive » Has runaway climate change begun?

Cross posted at Sustainable Kentucky and Tree Trends.

I’m giving a keynote speech at the Kentucky Governor’s Conference on the Environment.  Notes in preparation for the talk, which will include some discussion of forests and soils for carbon sequestration are at Sustainable Kentucky.

The Meteorological Office, Britain’s equivalent of our Weather Service, has a great short article that refutes the notion that global warming has slowed down.  The key paragraph is the first one:

"Anyone who thinks global warming has stopped has their head in the sand. The evidence is clear – the long-term trend in global temperatures is rising, and humans are largely responsible for this rise. Global warming does not mean that each year will be warmer than the last, natural phenomena will mean that some years will be much warmer and others cooler. You only need to look at 1998 to see a record-breaking warm year caused by a very strong El Niño. In the last couple of years, the underlying warming is partially masked caused by a strong La Niña. Despite this, 11 of the last 13 years are the warmest ever recorded."

This figure is also quite helpful

Global average temperature anomaly 1975-2007

Global average temperature anomaly from 1975 to 2007, relative to the 1961-1990 average.
The black line shows the annual figure. The red line shows the trend over the full 33 years.
The blue lines show the varying rate of the trend over 10-year periods.

Links:

Met Office: Global warming goes on

Cross posted at Sustainable Kentucky and Tree Trends.