Covering how environmental issues can influence population patterns often really comes down to numbers - and demographers often have just the numbers that journalists need.
Conversely, settlement and growth patterns can contribute to environmental vulnerability - for example when increasing numbers of people settle in low-lying coastal areas.
Here are some key resources for finding studies and statistics that can lead to intriguing human angles on environmental stories:
- In the US, the Population Association of America  is the leading professional association for demographers. Contact them to find members with expertise in environmental migration, or in your region. Contact: Mary Jo Hoeksema,  202-939-5456.
- The US Census Bureau  can supply detailed statistics on the US population (including immigrants). However, this data generally doesn't indicate why people are where they are in the US.
- Environmental migration - whether due to climate change or Superfund sites - can also affect housing prices, as described in this May 2006 paper  published in Land Economics.
- For still more population and demographic resources, see this resource list  from the Penn State Population Research Institute.
RESOURCES ON POST-KATRINA GULF COAST DEMOGRAPHIC SHIFTS
- "Climate Change and Out-Migration,"  by Rafael Reuveny,  School of Public and Environmental Affairs, Indiana University, 812-855-4944.
- Congressional Research Service: "Hurricane Katrina-Related Immigration Issues and Legislation,"  Ruth Ellen Wasem.
- Members of the Southern Demographic Association  could offer insight into hurricane-related population shifts along the Gulf Coast. Contact: Troy Blanchard,  Louisiana State University, 225-578-5123.
- The citizen journalism site ePodunk created an intriguing map of the Katrina diaspora. 
- Texas not only resettled many Katrina refugees, but also is on the front lines of immigration from Latin America. Members of the Texas Economic and Demographic Association  (TEDA) might be able to shed some light on current trends, statistics, and projections. Edith Chambers, 713-844-3618.
- United Nations University: Institute for Environment and Human Security; Media contact Ilona Roberts,  +49(0)228 815-0219, can provide a range of generalized publications on the topic. Pertinent experts are featured here.  They include Koko Warner, Fabrice Renaud, and J.J. Bogardi, who were authors of the 2007 publication "Control, Adapt, or Flee: How to Face Environmental Migration?" It is available, along with other publications, here.  Another publication, a 400-page book published in October 2006, is Measuring Vulnerability to Natural Hazards: Towards Disaster Resilient Societies. 
- EACH-FOR  (Environmental Change and Forced Migration Scenarios), a research project of the European Commission.
- The UN High Commissioner for Refugees looks at a different angle:  minimizing the environmental impacts of huge, sudden influxes of people to fragile habitats. Press: +41-22-739-8502.
- ReliefWeb. 
- Centre for Research on the Epidemiology of Disasters  (CRED): Rgina Below. 
- US Human Rights Network: Katrina campaign;  includes dozens of links to other organizations and publications about displaced persons and related issues.
- "Climate Change and Environmental Ruin Also Drives Migration,"  by Church World Service, June 18, 2007.