**Testimony of**

**Dr. John A. Helms**

**Professor Emeritus of Forestry**

**University of California, Berkeley,**

**and 2005 President of the Society of American Foresters**

**before the House of Representatives Committee on Energy and Natural
Resources**

**on Scientific Assessment of Effects of Climate Change on Wildfire**

**September 24, 2007**

**1. Introduction**

Chairman Bingaman, Ranking Member Domenici, and members of the Senate
Committee on Energy and Natural Resources. Thank you for the opportunity
to give testimony on scientific assessments of the impacts of global
climate change on wildfire activity in the United States. My name is
John A. Helms, Professor Emeritus of Forestry at the University of
California Berkeley where I served as Head of the Department of Forestry
and Resource Management. I am here today representing the Society of
American Foresters for which I served as President in 2005. The Society
has 15,000 members who are forest managers, consultants, academics, and
researchers and promotes sustainable forest management for balanced and
diverse values.

**2.** **Likely Magnitude of Climate Change**

This topic has been discussed at previous hearings, so I will not
elaborate here. However, since there is a direct relation between
climate and forests, and between the structure of forests and wildfire,
it is important to understand the likely magnitude of changed climate.

Due to the complexity of General Circulation Models there is
considerable uncertainty regarding the precise changes in climate.
However, there is general agreement that temperatures will increase
1-4°C in the next century resulting in less snow, more heat-absorbing
exposed ground and sea water, which lead to less reflectance or albedo
and provide positive feedback. On the other hand, there is continuing
uncertainty regarding the extent to which changes in clouds and
precipitation patterns may ameliorate increased temperatures. Average
temperatures have already changed several degrees especially in northern
latitudes. Maritime climates are already becoming wetter and interior of
continents drier. Glaciers and ice sheets are diminishing.

**3. Effect of Climate Change on Forest Ecosystems**

Throughout millennia, climate has been the principle determinant of
vegetation distribution throughout the world. Animal and plant species
are in a constant state of flux \-- continuously adapting, changing
distribution, evolving, and becoming extinct. At a finer scale, forests
have considerable adaptive capacity and can, for example, grow well on
both north- and south-facing slopes that have several degrees difference
in climate.

Scientific literature clearly documents changes in growing season,
phenology, and modified distribution of animals, plants, and insects. Of
particular concern is the extent to which likely increases in
temperature will cause changes in species distribution, how much climate
changes are being affected by human activities, and whether the rate of
change can be mitigated.

Projections of vegetation response to climate change are imprecise due
to differences in model assumptions on temperature change, temporal
patterns of rainfall, and likely responses of species to these changes.
However, in general, effects of climate change are more likely to be
seen in northern latitudes with loss of meadows, conversion of forest to
grassland, and tree invasion into areas that were previously too cold.
Forests are expected to move north in latitude and upward in elevation.
Pine forests at low elevation are likely to be replaced by woodlands and
grasslands. These shifts in biome boundaries are expected to be large.
It has been estimated that a temperature change of +3.5°C in the Rocky
Mountain zone is equivalent to vegetation habitat moving 2,000 feet up
slope or 200 miles further north (Ryan 2003).

Climate change will have considerable effects on forest growth, which
may increase or decrease depending on tree age, species, site quality,
and location. Within a given forest there will be changes in ecosystem
structure due to changes in species interaction and competitiveness. In
general, climate change is expected to lower productivity in the west,
and Alaska with higher productivity in the Northeast, Lake States, and
parts of the Southeast.

Carbon dioxide in the atmosphere can also limit growth. Experimentally
increasing atmospheric levels of CO~2~ have commonly shown that tree
growth increases up to 20 percent on fertile sites. Growth declines over
time since other factors such as nutrient availability or water then
become limiting. Interestingly, forest growth has increased in many
areas of the world due to added nitrogen from industrial pollution,
which further complicates analyses of tree growth responses to climate
change.

As forests are placed under increased temperature and water stress the
most observable feature will be loss of vigor and increased mortality as
species are no longer able to survive in the changed climate. This
decline in health and increased mortality and decay will add
substantially to carbon emissions \-- equivalent in some instances to
that due to deforestation. As species die and are replaced, soils will
be exposed, become warmer and subject to erosion, again releasing
substantial amounts of carbon to the atmosphere and compounding climate
change effects.

Already North American forests are showing evidence of stress and
apparent effects of climate change. A prime example is the mountain pine
beetle epidemic in lodgepole pine forests of British Columbia. Although
this beetle is endemic and, overall, is a positive and useful component
in the functioning of natural ecosystems, it appears that unusually hot,
dry summers and mild winters have increased beetle attacks and in 2006
about 23 million acres were affected (BC Ministry of Forests and Range
2007). Of particular concern is that, due to climate change, the
mountain pine beetle is likely to spread to Jack pine forests in Alberta
thus causing potential for increased wildfire.

A second example is pinyon pine in the Southwest where in some states
dieoff has reached 90 percent. The USDA Forest Service estimated in 2003
that about 3.8 million acres over six states were affected. Here again,
the precipitous decline in pinyon pine is associated with climate change
and drought. It seems that the winters have not been sufficiently cold
to restrict build-up in bark beetle populations. In addition, the
extensive tree mortality has been accompanied by a major decline of
pinyon jays and other ecosystem changes. In evaluating the effects of
climate change on forests, therefore, it appears that the area impacted
by insects are greater than that affected by wildfire.

A third cause of catastrophic change in forest ecosystems is hurricanes.
Increasing sea water temperature in the Gulf of Mexico is expected to
cause increased hurricane frequency and severity. Again, in the context
of climate change, the sudden removal of forests by hurricanes is likely
to increase opportunities for species to invade that are more adapted to
warmer conditions.

**4. Effect of Climate Change on Wildfires**

Lightning-caused fires have always been a major component of forest
ecosystems in the West. In addition, it is well documented that Native
Americans used fire extensively in controlling game, regenerating
desired plants, and for preventing surprise attacks from enemies. Prior
to the 1800s, it has been estimated that Native Americans in California
burned about 4.5 million acres of wildlands annually (Stephens et al.
2007). The National Interagency Fire Center estimates that during the
period 1825-1918 there were seven fires that were 1-3 million acres in
extent. Although these historic fires were very large, they probably
differed from contemporary fires which are more intense, crown fires
that result in stand replacement. This difference is primarily due to
past harvesting, regeneration, and fire suppression practices that have
resulted, especially on national forests, in stands having a high
proportion of shade-tolerant species, younger age classes, and higher
density of smaller trees than were characteristic of forests prior to
settlement. Similarly, major changes have occurred in plant species and
structure of the nation\'s grasslands due to grazing.

The National Interagency Fire Center also reports that humans have had a
major role in fire ignitions. In 2006, there were 96,380 wildfires of
which 83 percent were human-caused and human ignitions exceeded
lightning ignition in five out of 11 regions. Expressed in terms of
area, 9.8 million acres burned in 2006 of which 45 percent were
human-caused with human ignitions exceeding lightning ignitions in eight
out of 11 regions.

Clearly, then, it will be difficult to separate the effects of climate
change on wildfire occurrence from the effects of rapidly increasing
human populations in forested areas and the change in forest conditions
due to past forestry, urbanization, and other activities.

Never-the-less, weather is fundamentally important in influencing the
incidence and severity of wildfires, which due to climate change are
expected to increase in frequency and intensity (Keene et al. 1997, USFS
PNW 2004). One estimate is that wildfires will increase 50 percent by
2050 and double by 2100, with estimates varying depending on the climate
models used (Liu et al. 2004).

Higher temperatures and low humidity are important because they increase
the drying rate of fuels and increase the likelihood of drought and
length of fire seasons. Increased wind increases the rate of fire
spread. And climate change will likely increase the incidence of
thunderstorms and lighting. However, some areas will no doubt experience
decreased fire frequency. Areas of increased precipitation may moderate
fire behavior, but greater vegetation growth may also add to wildfire
potential. Further complicating predictions is that wildfires emit
considerable quantities of particulates that result in short-term
cooling by reducing solar heating. At the same time, wildfires
exacerbate climate change by emitting greenhouse gases to the
atmosphere. In 2005, wildfires in the U.S. resulted in 126.4 Tg CO~2~
(140 million tons) being emitted to the atmosphere (EPA 2007).

Although interactions among climate change, vegetation, human actions,
forest conditions, and insect and disease vectors are highly complex and
uncertain, wildfires will certainly be a major factor accelerating
species change and changes in plant distribution.

**5. Responsibility to Mitigate through forest management**

Since incidence and severity of wildfires are to a large extent
influenced by human ignitions and forest conditions, it is important to
consider the extent to which social sciences and forest management can
contribute to both understanding and mitigating wildfire occurrence and
intensity.

Monitoring climate change and forest conditions should be aimed at
separating out the complex factors and interactions that result in
wildfires. Since both growth and mortality on national forests greatly
exceeds harvest resulting in a build-up of fuels, it would be prudent to
consider treatments and incentives aimed at fuel reduction and using
excess biomass for societally-needed products and energy production. The
aim of such treatments on national forests would be to create, as far as
practicable, forest densities more suited to current societal usage so
that forests can better withstand the inevitable increase in wildfires
that climate change will cause.

**References Cited**

BC Ministry of Forests and Range 2007. Mountain Pine Beetle.
http://www.for.gov.bc.ca/hfp/mountain_pine_beetle/faq.htm#6

EPA 2007. Inventory of US Greenhouse Gas Emissions and Sinks: 1990-2005.
EPA 430-R-07-002.
http://www.epa.gov/climatechange/emissions/downloads06/07CR.pdf

Keene, R.E., C.C. Hardy, K.C. Ryan, and M.A. Finney. 1997. Simulating
Effects of Fire on Gaseous Emissions and Atmospheric Carbon Fluxes from
Coniferous Forest Landscapes. World Resources Review. 9(2): 177-205.

Liu, Y., J. Stanturf, H. Tian, and J. Qu. 2004. CO2 Emissions from
Wildfires in the U.S.: Present Status and Future Trends.
http://soilcarboncenter.k-state.edu/conference/Poster_pdfs/LiuYong_poster.pdf

Ryan, K.C. 2000. Global Change and Wildland Fire. Wildland Fire in
Ecosystems: Effects of Fire on Flora. Chapter 8. USDA Forest Service
Rocky Mountain Res. Sta. Chapter Gen. Tech. Rep. 042 Vol. 2.

Stephens, S.L., R.L. Martin, and N.E. Clinton 2007. Prehistoric Fire
Area and Emissions from Forests, Woodlands, Shrublands, and Grasslands.
For. Ecol. and Mgt. *In Press*.

USFS PNW 2004. Us Forest Service Pacific Southwest Station Science
Update Issue 6, 2004.

USDA/US Dept. Energy 2005. Biomass as Feedstock for a Bioenergy and
Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual
Supply.
http://www1.eere.energy.gov/biomass/pdfs/final_billionton_vision_report2.pdf