BIOGEOSPHERIC CHANGE

RESPONSE OF ECOSYSTEM STRUCTURE AND DISTRIBUTION TO ALTERED FORCING

© 2007 T. Kittel

Clarice Bassi - Anavilhanas

DRIVERS OF FUTURE ECOLOGICAL CHANGE: MULTIPLE FACTORS

Climate Change – Anthropogenic forcings:• Greenhouse gas emissions (GHG): CO2, CH4, N20, etc• Sulfate aerosols (SUL), Cloud condensation nuclei (dust, ..)• Landuse change Surface biophysical properties• Stratospheric Ozone

Disturbance – Landuse change:• Deforestation, cropland conversion• Overgrazing, desertification• Invasive species

Direct Chemical Effects:• CO2

• N deposition / acid deposition• Toxic pollution: Tropospheric ozone, Salt accumulation, …

The Source – Anthropogenic ForcingGreenhouse Gas Emissions

Dioxide

Increasing CO2 –

• Fossil fuels• Land conversion• Biomass burning

Effects =• Radiatively-active

Climate effect

• Biologically-active: Increased water and nutrient use efficiency Fertilization

Roads & fires - Amazon

Landcover Change

The Source – Anthropogenic Forcing

Changes in energetics & hydrology of the terrestrial surface

Changes in ecosystem biogeochemistry & emissions

Regional to global climate

Aircraft tracks, Bay of Biscay, E Atlantic

Aerosols – sulfate, dust, soot, sea salt, …

The Source – Anthropogenic Forcing

Haze / Cloud Condensation Nuclei

Changes in radiative properties of the atmosphere

Dust from Gobi Desert embedded in a storm approaching California

Manifestation of Change – Climate

1901-2002 Hemispheric Animation

Surface Air Temperatures

1850-2005

“We are entering a period of consequences” - Winston Churchill

Manifestation of Change – Climate

Precipitation

Manifestation of Change - Biosphere

Estimated changes in net primary productivity 1982-1999

• Increased North American NPP

The Future – Climate

• Projected Change – Annual Surface Air Temperature

2020’s 2090’s

Change (°C) relative to 1980-1999

Greatest response in the Northern High Latitudes

The Future – Climate

• Projected Change – Precipitation: Northern Winter

% Change relative to 1980-1999

2090’s

GLOBAL VEGETATION MODELS& the role of soil

(Kittel et al. 2000)

Structure of MC1

VEMAP2

REGIONAL VEGETATION RESPONSE

Animation: see notes pane for instructions

SCIENTIFIC UNCERTAINTIES: CLIMATE SENSITIVITY

• Emission scenarios Business-as-usual Carbon Stabilization

• Climate model differences

= the shaded envelop

Models similar conceptually

Different responses driven by –

Different model representations

Uncertainties in scaling up microphysical processes

– ppt, radiation & clouds

‘The devil is in the details’

Business as Usual

CO2 Stabilization

(http://www.ipcc.ch/present/graphics.htm)

CGCM1

HADCM2SUL MC1LPJ

• Model Uncertainty – Total Ecosystem Carbon

Uncertainty – Sources

“Same Ecology, Different Results”- at the regional level

• Total Ecosystem Carbon

Uncertainty – Sources

“Same Ecology, Different Results”- with time

(1) Very character of regional climates will likely change over the next decades:

• Multivariate Higher surface temperatures – different responses for

Tmin Tmax

Regionally varying changes in precipitation, cloud cover (light regime), wind regimes, etc.

• In means, but in also seasonality and interannual

variability• Trends likely not to be monotonic

As circulation patterns shift, & the system passes thresholds

• Giving rise to novel climates

The Certainties – Climate

“What do we know for sure?”

(2) Probable climate changes are of a magnitude and character to be significant for populations, communities, and landscapes:

• Geographic ranges

• Phenologies/life cycles

• Species interactions out of phase: Foodwebs, competition, pollination

• Ecosystem structure & function Resilience of many ecosystems is likely to be

exceeded

• Giving rise to novel ecosystem types

Certainties – The Biosphere

(3) The magnitude of uncertainties ≥ magnitude of system sensitivity

The magnitude of what’s certain will change everything

Certainties – The Biosphere

ACTION UNDER SUFFICIENT BUT LIMITED KNOWLEDGE?

“Least regrets” policy approach –

Develop policy that doesn’t rely on any single scenario of future change, but which reduces overall system vulnerability

• Maintain or restore integrity of natural systems Large preserves, landscape corridors, Clean Water Act … A focus on ecosystem services

• Develop infrastructure enhancing resiliency of socio-economic systems – to changes in climatic forcing regardless of direction

Landuse policy in areas currently prone to fire, flooding, hurricanes …

Individual Action –Carbon & ecological sustainabilityCommunity involvement