There were two excellent large scale studies released this week, one on the disaster of biodiversity loss, the other on the rapid changes in the temperature of the deep ocean beneath Antarctica. Both studies are done by large multi-national teams of highly respected researchers. Both are peer reviewed and published in the most respected scientific journals in their fields.
First out was the study 'Deep Ocean Beneath Antarctic Responding Rapidly to Climate Change'. The researchers in this case said, "The causes of the observed changes in the Southern Ocean are not yet fully understood. Changes in winds, sea ice, precipitation, or melt of floating glacial ice around the edge of Antarctica may be responsible. Further that, "The Southern Ocean is particularly important because it stores more heat and carbon dioxide released by human activities than any other region, and so helps to slow the rate of climate change," Dr Rintoul said. "A key goal of our work is to determine if the Southern Ocean will continue to play this role in the future."
Second is the study 'Biodiversity Loss Impacts as Great as Climate Change Impacts' The researchers found in their experiments that high levels of extinction had effects that were as great as ozone, acidification, elevated CO2 and nutrient pollution. "These extinctions may well rank as one of the top five drivers of global change." said ecologist Bradley Cardinale of the University of Michigan, one of the paper's co-authors. As a result, there has been growing concern that the very high rates of modern extinctions--due to habitat loss, over-harvesting and other human-caused environmental changes--could reduce nature's ability to provide goods and services such as food, clean water and a stable climate.
There are two types of science. One type is where operations are performed on consistant/controlled substances and whose results are repeatable, where there are controls and where the variables in each test can be changed so the various results can be compared. Of course, there we have only one earth so there can never be an unaltered control to test hypothesises against. Which brings us to the second type of science, that where the testing of hypothesises is done by running as many variables as possible on a computer model.
This modeling is always a rough [sometimes very rough] estimate of all the countless variables the real earth- the real environment has. Consequently all scientific experimentation done through modeling has some margin of error, no modeling type science can or will ever turn out an absolutely certain result. So all environmental science, all climate science, uses terms like may or could when stating their results. Here then is the door the skeptics always enter the conversation through. Nothing in climate science or environmental science can ever to certain to 100% because we only have one earth. Consequently scientists in those fields invoke the Precautionary Principle.