The National Center for Ecological Analysis and Synthesis has posted an atlas showing humans' impact on the oceans. Their site includes a downloadable file for Google Earth users. Researcher from the project were also featured on Talk of the Nation's Science Friday earlier today. (Embedded audio available.)
Their analysis is published in the February 15, 2008 issue of Science.
The NCEAS site says:
There were 4 steps to creating this composite map.
1. We gathered or created maps (with global coverage) of all types of human activities that directly or indirectly have an impact on the ecological communities in the ocean's ecosystems. In total, we used maps for 17 different activities in categories like fishing, climate change, and pollution. We also gathered maps for 14 distinct marine ecosystems and modeled the distribution of 6 others.
2. To estimate the ecological consequences of these activities, we created an approach to quantify the vulnerability of different marine ecosystems (e.g., mangroves, coral reefs, or seamounts) to each of these activities, published in Conservation Biology, October 2007. For example, fertilizer runoff has been shown to have a large effect on coral reefs but a much smaller one on kelp forests.
3. We then created the cumulative impact map by overlaying the 17 threat maps onto the ecosystems, and using the vulnerability scores to translate the threats into a metric of ecological impact.
4. Finally, using global estimates of the condition of marine ecosystems from previous studies, we were able to ground-truth their impact scores.